Preoperative and postoperative care

Published on 10/04/2015 by admin

Filed under Surgery

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1652 times

CHAPTER 5 Preoperative and postoperative care

Preoperative preparation 70
Postoperative care 71
Conditions affecting surgical risk 72
American Society of Anesthesiologists’ Classification of Physical Status (ASA grading) 78
Postoperative complications 78
Postoperative pain relief 88
Blood transfusion 89
Fluid and electrolyte balance 91
Nutritional support 94

Preoperative preparation

The purpose of preoperative evaluation is to identify the problems that may increase the operative risk and predispose to postoperative problems.

Assessment

1. Full history: present illness, past illnesses, bleeding tendencies, medication, allergies.
2. Examination: directed not only at the presenting complaint but also including a thorough examination of all systems, especially the cardiovascular and respiratory.
3. Laboratory tests: Hb, FBC and U&E for all but the most minor surgery.
4. Radiographs: CXR should be obtained in all patients with cancer, and cardiac, respiratory and renal disease. A routine preoperative CXR is unnecessary in young patients unless there are abnormalities on auscultation.
5. ECG: Obtain in all patients over the age of 40 and in those with a history of cardiac, respiratory or renal disease.

Principles of preoperative preparation

1. Correct any abnormalities that affect surgical risk.
2. Obtain informed consent. Explain all forms of possible treatment available for the condition. Explain the likely outcome without surgery. Explain the nature of the operation and the risks. Obtain the signature of the patient, parent or legal guardian. There is a special consent form for Jehovah’s Witnesses.
3. Details of preparation:

— nil by mouth for 4–6 h preoperatively
— i.v. fluids
— nasogastric aspiration
— bowel preparation
— medication planning, e.g. steroids, insulin, antihypertensives.

4. Laboratory investigations, e.g. blood sugar in diabetes, K+ in renal failure.
5. Cross-match of blood if major operation with expected blood loss.
6. Physiotherapy – breathing exercises.
7. DVT prophylaxis, e.g. graded compression stockings (thromboembolic deterrent – TED), subcutaneous low molecular weight heparin, e.g. Clexane.
8. Anaesthetic premedication.

Postoperative care

Monitor the patient’s progress at least daily postoperatively and more frequently if indicated. Record in the notes at least daily.

1. Detailed operation note including intraoperative drugs; postoperative instructions should accompany the patient to the ward.
2. Monitoring of vital signs. Monitor BP, pulse and respiratory rate every 15 min until the patient is stable and thereafter hourly for 24 h. Monitor CVP after major surgery in the elderly and those with cardiac disease. Continuous ECG monitoring is advisable in those with cardiac disease or elderly patients undergoing major surgery.
3. Early mobilization. Patients requiring prolonged bed rest should be turned regularly from side to side to avoid pressure sores. Nurse on airbed. Protect sacrum and heels, especially in diabetics.
4. Diet. Nasogastric tubes are used in a number of abdominal operations. However, increasingly, these are taken out at the earliest opportunity to allow the patient to eat. If the patient is at high risk of ileus, then they may be retained for 24–48 h. In operations not involving the GI tract, the patient may drink when fully awake after a GA.
5. Intravenous fluids. Administer according to requirements – monitored by clinical examination, urine output and CVP.
6. Intake/output chart. Monitor closely to avoid dehydration or fluid overload.
7. Urinary output. If the patient is catheterized, monitoring is easy. If the urine output falls below 30 mL/h action is required. If the patient is not catheterized, inform the surgeon if urine has not been passed within 8 h postoperatively.
8. Medication:

— Analgesics: the dose, frequency, and route of administration should be clearly indicated
— Antibiotics as indicated
— Routine medication as indicated; if the patient is ‘nil by mouth’, essential medication should be given parenterally.

9. Laboratory tests. After major procedures, the Hb, FBC and U&Es should be checked 24 h postoperatively and thereafter according to indications.
10. Radiographs and ECG. Carry out according to indications and not as routine. CXR may be necessary if pyrexia continues after 24 h postoperatively, if there is sputum production or chest signs.

Progress

The following points should be noted:

• General condition, e.g. well, ill, improving, deteriorating; pain
• Vital signs, e.g. pyrexia, tachycardia
• Mobility
• Chest, e.g. clear, reduced air entry, consolidation
• Abdomen, e.g. distended, bowel sounds, tender
• Legs, e.g. DVT
• Wound, e.g. discharge, infection
• Intake/output
• Diet
• Results of any laboratory tests.

Conditions affecting surgical risk

General problems in surgical patients

Age

Problems occur at the extremes of life. There are limits to cardiac, respiratory and renal reserves in the elderly. Fluid overload is tolerated poorly. Smaller doses of narcotics, sedatives and analgesics are required.

Obesity

This often results in poor wound healing and a higher incidence of respiratory problems. DVT and PE are more common. Pressure sores can develop. Delay elective surgery until the patient loses weight.

Compromised host

There is reduced response to trauma and infection, e.g. immunosuppressive drugs or uraemia. Malnutrition, e.g. vitamin deficiencies or liver disease, can also be a factor.

Allergies

Check for these preoperatively. Unsuspected reactions may occur. In severe cases, anaphylactic shock may result. Sensitivity to surgical dressings (e.g. Elastoplast) may occur.

Drugs

Current drugs should be monitored carefully, e.g. insulin and steroids. Diabetics may require conversion to sliding scale insulin (see below). Patients on steroids may need to continue their normal dose but with major surgery have additional steroid cover. Adjust anticoagulant therapy, e.g. conversion from warfarin to heparin over the perioperative period. Clopidogrel is contraindicated with regional anaesthesia (may cause epidural haematoma). Aspirin does not generally pose a problem in general surgical procedures. ACEI and ATII inhibitors should be stopped 24 h before surgery to prevent severe and refractive hypotension.

Medical problems in surgical patients

Cardiovascular

In elderly patients, the following are common: angina, cardiac failure, arrhythmias, valvular heart disease, hypertension, cerebrovascular disease, peripheral vascular disease. It is necessary to obtain a cardiology opinion, optimize medical treatment and assess operative risk. The decision to operate rests with the surgeon and anaesthetist.

MI and angina

Unstable angina and recent MI greatly increase the operative risk. Emergency surgery following recent MI has a mortality of 30%. Delay elective surgery for 6 months.

Cardiac failure

Treat prior to surgery. Stabilize at least 1 month prior to surgery. Digoxin. Diuretic. Check K+ prior to surgery. Mild CCF well controlled with digoxin and diuretics carries little risk. CCF with dyspnoea on exertion, orthopnoea and PND carries a significant risk.

Arrhythmias

Uncontrolled AF may cause perioperative CCF. Digitalize adequately preoperatively. Some degrees of heart block require a prophylactic temporary transvenous pacemaker. Check digoxin levels in patients who have bradycardia. Arrhythmias developing during surgery may be due to hypoxia, hypercapnia or high or low K+.

Valvular heart disease

May result in MI, CCF, arrhythmias, embolism or bacterial endocarditis in the perioperative period. Newly discovered murmurs require a cardiology opinion. Elective cases should be deferred until the murmur has been evaluated. Prophylactic antibiotics are important in the perioperative period and for patients with prosthetic valves. Check if patient is on anticoagulants.

Hypertension

Mild hypertension without renal or cardiac complications does not significantly affect surgical risk. Control BP at or below 160/95 mmHg. Defer and investigate elective cases with newly diagnosed hypertension. Check K+ in patients on diuretics. Severe and poorly controlled hypertension should be adequately controlled prior to surgery.

Cerebrovascular disease

High risk of intraoperative CVA. Previous history of TIAs or stroke. Carotid bruits. Aspirin may be protective. Avoid intraoperative hypotension.

Peripheral vascular disease

Patients with peripheral ischaemia may develop arterial thrombosis if hypotensive. Take care to avoid pressure sores, which may not heal and lead to the need for amputation.

Respiratory disease

This is a major cause of postoperative morbidity and mortality in the elderly. COPD, asthma, and bronchiectasis are precipitating causes. Smoking, obesity, old age, general debility and cardiac disease are contributory. Preoperative investigations include CXR, lung function tests (e.g. FEV1, peak expiratory flow rate, spirometry), sputum culture, ABG.

Perioperative management of respiratory disease

• Stop smoking. Preferably 4 weeks prior to surgery
• Preoperative chest physiotherapy and breathing exercises
• Drugs, e.g. bronchodilators, nebulized salbutamol, antibiotics
• Anaesthetic – local or spinal if possible
• Analgesia. Avoid narcotic analgesics that may lead to respiratory depression. Consider epidural pain relief
• Postoperative physiotherapy
• Early mobilization.

Renal disease

This should be managed jointly with a nephrologist. Symptoms of renal failure do not usually become apparent until 80–90% of renal function has been lost and there is little renal reserve.

Mild impairment of renal function

Mildly raised urea or creatinine. Refer to a nephrologist and delay elective surgery until a diagnosis has been reached and appropriate treatment instituted. Deterioration of renal function may occur after major surgery, especially if dehydration is allowed to occur. Adequate preoperative rehydration. Monitor CVP. Caution with nephrotoxic drugs, e.g. gentamicin.

Grossly impaired renal function (non-dialysis dependent)

Inadequate management may precipitate end-stage renal failure. Problems include fluid overload, dehydration, hyperkalaemia, metabolic acidosis. Chronic anaemia occurs but patients are well adapted to this. Uraemia is immunosuppressive and prophylactic antibiotics are required. Uraemia alters platelet function and bleeding may be a problem.

Dialysis-dependent renal failure

Haemodialysis

Dialysis should take place 24 h prior to surgery to allow the effects of heparin to wear off. Check U&Es, creatinine, and HCO3 post-dialysis. CXR to exclude pulmonary oedema. Check K+ postoperatively as hyperkalaemia may occur following surgery under GA. If possible, delay postoperative dialysis for 24 h in view of risk of bleeding with heparin.

Continuous ambulatory peritoneal dialysis (CAPD)

Check U&Es prior to surgery. If abdominal surgery, CAPD may need to be discontinued and patient instituted on haemodialysis via a central line until intra-abdominal healing has occurred.

Hepatic disease

There is a high incidence of morbidity and mortality with cirrhosis. Predisposing factors are anaemia, electrolyte disturbances, abnormal clotting, malnutrition, abnormal drug metabolism, ascites, portal hypertension. Defective synthesis of clotting factors in the liver and thrombocytopenia due to hypersplenism may result in excessive bleeding. The Child–Pugh score can be used to assess the ‘hepatic reserve’, the higher the score the greater the operative risk (measures albumin, bilirubin, prothrombin time and the presence and severity of ascites and encephalopathy).

Care must be taken to assess a past history of jaundice. This may be due to hepatitis, obstructive jaundice or haemolytic disease.

Hepatitis

Hepatitis A in the past carries little risk; hepatitis B and C may be carried permanently. Check HBsAg.

Obstructive jaundice

There is usually a clear history. Surgery will usually have been necessary to deal with the problem.

Haemolytic disease

May cause jaundice.

Perioperative management of patients with liver disease/obstructive jaundice

1. Full clinical examination
2. Hb, FBC, U&Es, Cr, LFTs, PT, glucose
3. Correct hypoglycaemia
4. Correct coagulation defect, e.g. vitamin K parenterally, but in severe disease FFP may be required. Platelet transfusion
5. Avoid saline infusions (risk of hypernatraemia)
6. Avoid hepatotoxic drugs
7. Avoid drugs metabolized by liver, e.g. opiates
8. Correct protein deficiency
9. Antibiotics.

The main postoperative problems are bleeding, infection, and poor wound healing.

Haematological disease

Anaemia

Mild anaemia, e.g. Hb >10 g/dL, imposes little risk. Anaemia may be related to the condition for which surgery is being undertaken, e.g. GI cancer. Hb <10 g/dL should be treated by preoperative iron therapy or transfusion. Unsuspected anaemia noted prior to elective surgery should be investigated and the operation deferred.

Polycythaemia

Hb >18 g/dL. PCV ↑. Risks of arterial and venous thrombosis. Venesect prior to surgery. Myelosuppressive drugs may be required.

Bleeding disorders

Inherited

Haemophilia is treated with cryoprecipitate preoperatively and until the danger of postoperative haemorrhage is over. Von Willebrand’s disease is treated with FFP or cryoprecipitate.

Anticoagulant therapy

Warfarin – the patient may have a history of thromboembolic disease, valvular heart disease or prosthetic heart valves. Anticoagulation may need to be continued during surgery, albeit at a reduced level. The safest procedure is to discontinue warfarin 3–4 days preoperatively and start heparin i.v. This can be more readily adjusted and is more easily reversed (with i.v. protamine sulphate) if bleeding occurs. If a patient’s INR needs to be reduced for urgent operation, then they may be given vitamin K (takes 4 h to work), FFP or in extreme cases, can be given prothrombin complex concentrate (Beriplex) that will reverse the warfarin in under 30 min.

Disseminated intravascular coagulation (DIC)

Coagulation and fibrinolysis occur simultaneously. Surgically important causes precipitating the condition include Gram-negative septicaemia, acute pancreatitis, malignancy, major surgery, e.g. ruptured aortic aneurysm. Clinical features include extensive bruising, oozing from drip and venepuncture sites, oozing from the wound, tracheostomy or bowel occurring in a severely ill patient. Diagnosis is confirmed by PT (prolonged); PTT (prolonged); thrombocytopenia; decreased fibrinogen level; raised FDPs. Treatment is by FFP, platelets and cryoprecipitate. Heparin i.v. may halt the coagulation element. Aggressive treatment of the underlying disease.

Clotting disorders

Acquired

Anti-phospholipid syndrome (associated with SLE; there is a higher risk of venous and arterial thrombosis. However, unless there is a history of thrombosis, no further intervention is required other than normal DVT prophylaxis) and malignant thrombosis associated with advanced malignancy (all patients are considered high risk for a DVT).

Inherited

These include antithrombin deficiency, protein C and protein S deficiency, Factor V Leiden and Prothrombin 20210A. These patients will require rigorous DVT prophylaxis, particularly if they have had a previous thrombosis.

Sickle cell anaemia

These patients are at increased risk of surgical complications. Homozygote patients have 90–100% HbS. They may require transfusion if they are anaemic; or to decrease the amount of HbS. Heterozygote patients or those with the sickle cell trait have 20–40% HbS and are generally asymptomatic. Surgery and anaesthesia may lead to dehydration, hypoxia and vascular stasis. These may then lead to a sickle cell crisis with pain and ischaemia (even in trait patients). This can be avoided by adequate hydration, supplemental oxygen and avoiding blood stasis (e.g. pneumatic compression stockings and avoidance of the use of tourniquets).

Endocrine disease

Diabetes

This poses numerous risks and affects many systems. Complications include:

• Vasculopathy: heart – increased risk of MI; peripheral vascular disease (PVD) – risk of lower limb ischaemia with ulcers and gangrene; risk of stroke
• Nephropathy – risk of CRF
• Neuropathy – peripheral neuropathy with risk of pressure ulcers on heels and autonomic neuropathy with risk of cardiac arrest and gastric stasis with aspiration
• Retinopathy leading to blindness – problems with management of blind patient in unfamiliar surroundings; anticoagulation, if needed, may make retinal haemorrhage worse
• Increased incidence of infection.

The principles of management of diabetes in the perioperative period depend on whether patients are insulin dependent, on oral hypoglycaemics or controlled by diet.

Insulin-dependent

1. Admit 2 days preoperatively: CXR, ECG, FBC, U&Es, glucose, glycosylated Hb (HbA1C)
2. Establish good diabetic control (glucose 4–10 mmol/L)
3. First on morning list. Check glucose
4. Dextrose/insulin/K+ infusion
5. Check glucose intraoperatively and U&Es postoperatively
6. Monitor glucose regularly in early postoperative period
7. Continue infusion until full oral diet is established and then reinstitute normal insulin regime.

Oral hypoglycaemics

1. Review control
2. Major surgery: convert to insulin/glucose/K+ infusion as above
3. Minor surgery: omit oral hypoglycaemic agent. Check blood sugar. If greater than 13 mmol/L give small dose of subcutaneous insulin.

Diabetics controlled by diet alone

1. Review control
2. If preoperative control is adequate, no other measure required other than routine check of blood sugar pre- and postoperatively.

Thyroid disease

Hypothyroidism

Patients should be euthyroid prior to elective surgery. Emergency surgery in a patient who is clinically hypothyroid presents a very high risk. Patients are at risk from MI, hypotension, hypothermia, hypoglycaemia and hyponatraemia (may cause convulsions) and coma (hypothyroid coma has a 50% mortality).

Hyperthyroidism

Patients should be euthyroid prior to elective surgery (→ Ch. 11). Hyperthyroidism is associated with arrhythmias and hypertension. A thyroid crisis is associated with oversecretion and may be triggered by infection. This presents as hyperthermia, arrhythmias, cardiorespiratory failure and coma.

Adrenal disease

Adrenocortical insufficiency

This may be due to destruction of the adrenal gland by autoimmune disease, tumour, infection, infarction or the sudden withdrawal of steroid therapy. It should be considered in all patients with postoperative hypotension that is refractory to fluid replacement or inotropes with no obvious cause. Patients taking steroids, or who have taken steroids in the last 9 months, should have supplemental steroid cover. A guide to additional hydrocortisone cover is 25 mg i.v. hydrocortisone at induction for minor surgery; 25 mg i.v. hydrocortisone at induction; followed by 100 mg in the postoperative period for moderate surgery, and 100 mg hydrocortisone on induction followed by 100 mg 6-hourly for 48 h or until blood pressure is stable, in major surgery.

Cushing’s syndrome

Patients have excess levels of glucocorticoids and are at risk of hypertension, hypokalaemia, hypernatraemia and diabetes. May be corrected by metyrapone which inhibits steroid synthesis. These patients are often obese, making surgery more challenging with poor wound healing and increased risk of respiratory complications.

American society of anesthesiologists’ classification of physical status (ASA grading)

When an operation is planned and there are problems concerning the patient’s fitness for anaesthetic, then the anaesthetist should be involved as soon as possible. The American Society of Anesthesiologists has produced a grading system that attempts to quantify the risks of anaesthetizing patients with various clinical conditions.

The ASA grading system for quantifying anaesthetic risk is as follows:

I. A healthy patient with no systemic disease process, e.g. a fit patient with an inguinal hernia.
II. A patient with mild to moderate systemic disease process caused either by the condition to be treated surgically or by other pathological process which does not limit the patient’s activity in any way, e.g. mild diabetic, treated hypertensive.
III. A patient with a severe systemic disturbance from any cause and which imposes a definite functional limitation on the patient, e.g. severely limiting organic heart disease, severe diabetes with vascular complications, severe COPD.
IV. A patient with severe systemic disease which is a constant threat to life, e.g. severe unstable angina, advanced liver failure.
V. A moribund patient who is unlikely to survive 24 hours with or without surgery, e.g. ruptured aortic aneurysm in a patient with severe COPD.

Postoperative complications

All operations carry a risk of complications (a Classification is shown in Table 5.1). Complications may be divided as:

TABLE 5.1 Postoperative complications

Haemorrhage Early postoperative
Secondary haemorrhage
Wound Infection
Bleeding
Haematoma
Seroma
Suture sinus
Breakdown:

• burst abdomen
• incisional hernia
• anastomotic breakdown: peritonitis, abscess, fistula

Cardiovascular Cardiac arrest
MI
Pulmonary oedema
Arrhythmias
DVT Lung Atelectasis
Aspiration
Pneumonia
PE
Pulmonary oedema
Pneumothorax
ARDS Cerebral Confusion:

• sepsis
• electrolyte/glucose
• hypoxia
• alcohol withdrawal

Stroke

Urinary Acute retention
UTI
Acute renal failure Gastrointestinal Paralytic ileus
Mechanical obstruction
Acute gastric dilatation
Constipation Other Pressure sores

• General complications of any operation
• Specific complications of individual operations
• Timing of complication, e.g. immediate, early or late.

Specific complications and timing of complications are discussed in relation to specific operations and conditions in the various chapters in this book.

Haemorrhage

Early postoperative

Inadequate haemostasis, unrecognized damage to blood vessels, defective vascular anastomosis, slipped ligature, massive blood transfusion without adequate clotting factors, use of intraoperative anticoagulants, e.g. in vascular surgery. Treatment depends on cause. Check clotting screen. Surgical re-exploration is usually required.

Secondary haemorrhage

Several days postoperatively. Related to infection, which erodes vessels. Treatment of the infection and appropriate surgery to deal with the bleeding.

Wound problems

Infection

Incidence varies according to type of surgery and potential for contamination (→ Ch. 6). Factors leading to increased risk of wound infection include: haematoma, poor nutritional state, diabetes mellitus, reduced immunity, nasal carriage of Staphylococcus aureus.

Symptoms and signs

Painful red incision with discharge. General malaise. Examination reveals pyrexia, red, hot, tender wound. A purulent discharge may be apparent.

Treatment

1. If pus is present, it should be evacuated.
2. Culture and sensitivity of pus.
3. Appropriate antibiotic if cellulitis present or compromised patient, e.g. diabetic, steroids.
4. If cavity present, pack with alginate dressings, e.g. Sorbsan. A larger cavity may require a period of vacuum assisted closure, e.g. VAC.

Wound breakdown

Factors which delay wound healing include: old age, obesity, malnutrition, poor vascularity, sepsis, carcinoma, jaundice, uraemia, steroids, haematomas, raised intra-abdominal pressure.

Burst abdomen

This is a sudden bursting of the wound revealing bowel. This is often preceded by discharge of a salmon pink fluid (Pink sign). Usual cause is inadequate suturing of abdominal wall. Coughing, straining at stool, may be contributory. Cover the abdominal contents with sterile saline-soaked packs. Return the patient to theatre and repair with large bites of whole thickness of the abdominal wall using deep tension sutures. This complication has a mortality around 20%.

Incisional hernia

The overall incidence is about 10%. In addition to factors delaying wound healing, causes include poor suture technique, raised intra-abdominal pressure (e.g. paralytic ileus), coughing, straining (e.g. constipation), prostatism. Rarely a broken suture is responsible. These herniae often have a wide neck and strangulation is rare.

Treatment

If the patient is unfit, a surgical belt may be worn. If the patient is fit, surgical repair should be carried out.

Anastomotic breakdown

This is a major cause of postoperative morbidity and mortality after bowel surgery.

Causes

These include:

• Poor surgical technique
• Ischaemia at the anastomosis
• Perioperative sepsis
• Distal obstruction
• Residual inflammatory disease, e.g. Crohn’s or malignant disease
• General condition, e.g. uraemia, jaundice, malnutrition, steroids.

Anastomotic breakdown may result in generalized peritonitis, paracolic abscess, abscesses between loops of bowel or fistula formation. However, presentation can be surprisingly subtle with mild pyrexia, persistent tachycardia and general failure to progress as the only signs of anastomotic leak (→ Chs 6 and 14).

Haematoma

This is a localized collection of blood beneath the wound. May be an obvious tender mass with surrounding bruising. Treatment is by aspiration percutaneously or may require opening of the wound and clot evacuation.

Seroma

This is a localized collection of serous fluid. Often where skin flaps have been raised, e.g. chest wall in mastectomy, or where lymphatics have been divided, e.g. groin or axilla. Examination reveals a non-tender fluctuant mass. Small areas may be left and may absorb spontaneously or they may be needled percutaneously. Large ones may need formal drainage.

Stitch sinus

Sutures may act as nidus of infection, especially at the knot. Less common, since absorbable sutures and monofilament nylons replaced silk. Often the suture will extrude through the sinus spontaneously and the sinus will then heal. Occasionally, exploration and removal of the suture is required.

Cardiovascular problems

Cardiac arrest following surgery is usually due to an underlying cardiac condition aggravated by a precipitating cause, e.g. hypoxia, shock, MI, anaesthetic overdose, hyperkalaemia, hypokalaemia or drug reactions. Cardiac arrest may follow respiratory arrest, e.g. following an obstructed airway (laryngeal oedema or tongue blocking airway) or inhalation of vomit. DVT may follow prolonged bed rest.

Lung problems

Lung complications are a common postoperative problem. They include atelectasis, aspiration, pneumonia, PE, pulmonary oedema, pneumothorax and ARDS.

Atelectasis

Mucus is retained in the bronchial tree, blocking the smaller bronchi and resulting in absorption of alveolar air with collapse of an area of lung. Infection may then occur and progress to pneumonia. Minor degrees are common. Smoking and COPD are predisposing factors. Anaesthesia may increase bronchial secretions and depress ciliary action. Postoperative abdominal pain inhibits coughing and allows secretions to accumulate.

Symptoms and signs

Minor atelectasis may be accompanied by mild pyrexia alone; greater degrees are accompanied by dyspnoea, tachypnoea, rapid pulse and elevated temperature. Major degrees may be accompanied by cyanosis and respiratory collapse. The signs include widespread rales, reduced air entry and dullness to percussion.

Diagnosis

Clinical:

• CXR
• ABG
• Sputum culture.

Treatment

Minor degrees require only chest physiotherapy. Adequate pain relief facilitates mobility and physiotherapy. Nebulized bronchodilators. More severe degrees may require bronchoscopy to remove mucus plugs. The most severe case may require intubation and ventilation.

Aspiration

Aspiration pneumonitis following inhalation of acidic gastric contents is known as Mendelson’s syndrome. This tends to affect the right lung more than the left as the right bronchus is wider and more in line with the trachea. Aspiration may occur during induction, or at the termination, of anaesthesia. It may also occur in patients with bowel obstruction or paralytic ileus who vomit in the early postoperative period. Prevention includes preoperative ‘nil by mouth’ in elective cases, nasogastric suction in the emergency case and cricoid compression in ‘crash’ induction. If aspiration occurs, suction, intubation and saline lavage should be carried out. Steroids may help. Antibiotics will prevent super-added infection. Oxygen by mask.

Pneumonia

Predisposing factors include smoking, atelectasis, COPD, aspiration, debilitated patients.

Symptoms and signs

Cough, respiratory distress, sputum. Signs include fever, tachypnoea, tachycardia, cyanosis, consolidation and rales.

Diagnosis

• Sputum culture
• CXR
• ABG.

Treatment

Chest physiotherapy. Antibiotics, e.g. Amoxicillin or Septrin until results of culture are known. Oxygen by mask. If no improvement with basic measures the patient may need to be moved to a critical care facility for CPAP or intubation and ventilation.

Pulmonary oedema

Usually elderly patient with compromised cardiac function or young patient with history of cardiac or renal disease.

Symptoms and signs

Tachypnoea, tachycardia, orthopnoea, raised JVP, pink frothy sputum, widespread crepitations.

Diagnosis

• CXR
• Raised JVP
• Elevated CVP.

Treatment

Stop i.v. fluids. Sit patient upright. Oxygen by face mask. Give i.v. furosemide. Small doses of opiates. GTN/i.v. infusion of nitrates.

Pulmonary embolus (PE)

Complication of silent or overt DVT. Passage of a clot from pelvic or leg veins into the pulmonary artery. Major PE with overt DVT is usually obvious clinically. In some cases, diagnosis relies on a high index of clinical suspicion.

Symptoms and signs

Usually 4–10 days postoperatively. Sudden dyspnoea and collapse. Hypotension. Pleuritic chest pain. Haemoptysis. Pleural rub.

Diagnosis

• CXR: wedge-shaped collapse
• ECG: right heart strain, S1, Q3, T3 pattern
• ABG: hypoxia
• V/Q scan: mismatch of ventilation/perfusion areas, i.e. ventilation normal but perfusion deficient (rarely performed now)
• CT pulmonary angiogram (CTPA) – most commonly used test
• Pulmonary angiography is most accurate – used prior to surgery or thrombolysis.

Treatment

• Patients without shock. They may be treated by i.v. heparin sufficient to maintain the APTT at 2.5 × normal. Start warfarin after 2 days of heparin and continue for 6–9 months. With recurrent pulmonary emboli it should be continued for life.
• Profound shock. Inotropic support. Urgent pulmonary angiography. Thrombolytic therapy or pulmonary embolectomy.
• Recurrent pulmonary embolus. This should be treated by insertion of a filter, e.g. Greenfield filter percutaneously via the venous route into the IVC.

Pneumothorax

Rare complication of surgery. Rupture of subpleural bulla or complication of insertion of central line perioperatively.

Symptoms and signs

Respiratory distress. Reduced breath sounds and hyper-resonance to percussion of affected side.

Treatment

• Small: treat expectantly
• Large: chest drain.

Adult respiratory distress syndrome (ARDS; shock lung)

This is acute respiratory failure with tachypnoea, hypoxia, decreased lung compliance and diffuse pulmonary infiltrates on CXR. The exact aetiology is unknown but there is interference with the pulmonary epithelial/endothelial cell interface with increased interstitial oedema, vascular congestion and ultimately fibrosis (Table 5.2).

TABLE 5.2 Causes of ARDS

Infection Septicaemia
Inhalation Smoke, vomit, water, high O2 concentrations, chlorine, ammonia
Embolism Fat, amniotic fluid, air
Cerebral Head injury, cerebral haemorrhage
Drugs Opiates, barbiturates
Others Pancreatitis, DIC, blood transfusion, cardiopulmonary bypass, major trauma with shock

Symptoms and signs

Present a few days after diagnosis of a serious underlying condition. Breathlessness, deterioration in clinical condition.

Investigations

• CXR shows whiteout with sparing of costophrenic angles
• ABG: hypoxia resistant to oxygen administration
• May be difficult to distinguish from pulmonary oedema in early stages but latter usually shows cardiomegaly on CXR and response to diuretics.

Treatment

1. Treat the underlying disease, e.g. septicaemia.
2. Treat the pulmonary problem:

— mechanical ventilation to maintain PaO2. PEEP may be necessary
— monitor fluid balance. CVP to monitor right atrial pressure. Left atrial pressure is monitored as pulmonary wedge pressure with a Swann–Ganz catheter
— careful monitoring for development of secondary lung infection. Administration of appropriate antibiotics
— renal failure is a common complication. Early administration of dopamine in renal doses may be appropriate.

The mortality rate for ARDS is 70–90%.

Cerebral problems

Confusion

Confusion postoperatively is not uncommon, especially at night in the elderly. However, there may be an underlying cause, e.g. sepsis, hypoxia, alcohol withdrawal, electrolyte or glucose imbalance, cerebral bleed, postoperative pancreatitis, opiate analgesia.

Investigations

• Hb
• FBC
• U&Es
• Glucose
• Amylase
• ABGs
• Blood culture
• Urine analysis
• Sputum culture
• CXR
• Brain scan.

Treatment

• Correct electrolyte or glucose disturbance.
• Correct hypoxia – 35% oxygen by mask or nasal cannula.
• Investigate and treat any sepsis.
• Tranquillizers may be required, e.g. chlorpromazine or haloperidol.
• For acute alcohol withdrawal, i.v. clomethiazole and parenteral vitamin B may be used, although 60 mL of medicinal brandy may be more appropriate.

Stroke

May occur in the elderly postoperatively. Avoid intraoperative hypotension in patients with TIAs or carotid bruits.

Urinary tract problems

Acute retention

Common postoperatively, especially in elderly males.

Symptoms and signs

Usually suprapubic discomfort, although this may not be apparent because the patient has been given analgesia postoperatively. Usually nurse reports that patient has not passed urine for several hours postoperatively. Examination reveals a palpable bladder dull to percussion. If the patient has no desire to micturate and the bladder is not palpable, oliguria must be considered and corrected.

Treatment

Conservative. Ensure adequate analgesics. Stand patient up. If no benefit, and the patient is fit enough, take to bathroom and leave tap running to encourage micturition. If conservative measures fail, pass a urinary catheter.

Urinary tract infection (UTI)

This is common, especially in females. Catheterization may predispose.

Symptoms and signs

Dysuria/frequency/dribbling/smelly urine. May be found on investigation of undiagnosed pyrexia postoperatively.

Investigations

MSSU.

Treatment

Appropriate antibiotic.

Acute renal failure (ARF)

Oliguria is passage of <30 mL of urine per hour. Anuria is failure to pass any urine.

Causes

Prerenal

Reduced cardiac output, shock, e.g. hypovolaemic, cardiogenic, septic.

Renal

Pre-existing renal disease, e.g. diabetes, glomerulonephritis. Nephrotoxic drugs, e.g. gentamicin. Myoglobinuria in crush syndrome. Haemoglobinuria with haemolysis.

Postrenal

Obstruction, e.g. damage to ureters, benign prostatic hypertrophy.

Treatment of anuria/oliguria

1. Check that the catheter is patent. If patient not catheterized, then pass catheter.
2. Check BP to exclude hypotension.
3. Fluid challenge, e.g. 1 L normal saline over 1 h. Give sufficient fluid to restore CVP. If elderly patient, a fluid challenge is best done with CVP monitoring.
4. If no improvement in urine output after adequate fluid administration and the BP is low then the patient may require transfer to a critical care/high dependency facility for inotropic support.
5. Check ABG (for acidosis), K+ and HCO3−. Serum urea and creatinine. ECG (signs of hyperkalaemia).
6. Stop any nephrotoxic drugs.
7. Contact renal physician and manage jointly. In the presence of hyperkalaemia and metabolic acidosis, dialysis will be required until a diuresis ensues. Fluid overload may be treated with CVVH.
8. Furosemide is generally not used to increase a patient’s urine output unless they are in CCF.

Gastrointestinal problems

Paralytic ileus

This is the cessation of GI motility. Aetiological factors include fractures of the spine and pelvis, retroperitoneal haemorrhage, peritonitis, hypokalaemia, drugs, e.g. ganglion blockers and anticholinergic agents, abdominal surgery, immobilization. Atony of the bowel may be expected for 24–48 h postoperatively. Paralytic ileus continuing after 48 h may have an underlying cause.

Symptoms and signs

Abdominal distension, vomiting, constipation. Tense tympanitic abdomen. Absent bowel sounds (Table 5.3).

TABLE 5.3 Factors distinguishing paralytic ileus and mechanical obstruction

  Ileus Obstruction
Time Usually settles in 3–4 days May persist longer
Bowel sounds Absent High-pitched and tinkling
Pain Painless Colicky abdominal pain
AXR General gaseous dilatation of small and large bowel Localized small bowel distension with absent gas in colon and rectum

Investigations

AXR: gaseous distension with fluid levels throughout the large and small bowel.

Treatment

1. Pass NG tube and aspirate hourly.
2. Ensure adequate hydration.
3. Correct any potassium imbalance.
4. Paralytic ileus rarely lasts for more than 4 days.
5. If symptoms persist, look for continuing cause and exclude mechanical obstruction with an abdominal CT.

Mechanical obstruction

Early (within 2 weeks of surgery)

May be due to fibrinous adhesions. Obstruction may settle with i.v. fluids and nasogastric suction or it may progress and require laparotomy.

Late (after 2 weeks)

May be due to obstruction by adhesions – fibrous bands arising as part of peritoneal healing. Symptoms may settle with i.v. fluids and nasogastric suction. If they do not or signs of strangulation appear, laparotomy will be necessary.

Gastric dilatation

Acute gastric dilatation may occur in the early postoperative period and may be associated with shock. Vomiting with aspiration may occur.

Treatment

NG suction, which may aspirate several litres of brownish/black fluid with altered blood. Fluid and electrolyte losses must be replaced.

Constipation

Uncomfortable for patient. Precipitating factors include starvation, dehydration, inactivity, opiates.

Treatment

1. Check daily if patient has had bowels open. Do not delay treatment.
2. Lactulose should be given as soon as the patient is eating.
3. Glycerine suppositories. PR to exclude faecal impaction.
4. Enemas may be required. With faecal impaction, oil enemas may be necessary.
5. Attention to diet. High-fibre diet or bulking agent.

Postoperative pain relief

Pain must be expected from most surgical procedures but it usually subsides gradually over the first few days. Patients respond differently to pain. However, excess pain in the postoperative period may be a symptom of a developing complication.

Methods of postoperative pain control

Full explanation of the operation and postoperative course and an attempt to relieve preoperative anxiety may reduce the severity of postoperative pain.

Oral analgesia

First-line analgesia for patients that are tolerating diet usually used for mild to moderate pain, e.g. groin hernia repair or varicose vein surgery. Suitable agents include paracetamol, NSAIDs, nefopam, weak opioids such as codeine and oral morphine (Oramorph).

Parenteral analgesia

Intermittent intramuscular opiates

Commonly used. Usually given p.r.n., 4-hourly. Many patients still complain of pain.

Intravenous opiates

Given for acute pain. Dose titrated to gain adequate pain relief. Beware respiratory depression in the elderly and patients with renal failure.

PCA pump

This device allows patients to self-administer a preset dose of analgesic drug by pressing a button connected to a pump. This in turn is connected to an i.v. cannula. There is a preset interval before the infusion will deliver another dose, i.e. the ‘lock-out’ time. This is a very effective method of pain control but is expensive.

PCEA pump

This is similar to the above but is administered as an epidural.

Spinal

LA is placed in the intrathecal space. This allows a period of regional anaesthesia for several hours or may be ‘topped’ up if a catheter is left in situ. Not used for pain relief in the postoperative period.

Epidural

A catheter is placed in the epidural space and LA or opioids may be infused. This can be as a continuous infusion or as a patient controlled pump.

Intercostal nerve blocks

These are useful for upper abdominal surgery or in thoracic injuries, e.g. fractured ribs

Direct infiltration

Bupivacaine, a long-acting local anaesthetic, can be injected directly into the wound, e.g. for repair of an inguinal hernia. It may be also injected around the nerve supplying the area of the wound, e.g. the ilioinguinal nerve in hernia repair. Infiltration of local anaesthesia may be continuous with catheters placed in between the muscles of the abdominal wall in which the sensory nerves run.

Blood transfusion

Blood transfusion is not without risk. Decision to transfuse blood should have a clear indication and alternative therapy, e.g. plasma substitutes for hypovolaemia and iron therapy for anaemia should be considered first. Screening programmes for HIV, hepatitis B and C have made transfusions safer. Unless a patient has severe cardiorespiratory disease (generally need Hb >10 g/dL in these patients) there is no change in cardiac output until Hb falls below 7 g/dL. In chronic anaemia, even lower levels may be tolerated.

There are numerous different blood types but the two most common systems are the ABO system and the Rhesus status. ABO is divided into type O (46%), A (42%), B (9%) and AB (3%). Rhesus is divided into positive (85%) and negative (15%). Therefore O Rh positive is the most common and AB Rh negative is the rarest.

Blood products and alternatives to transfusion

Blood products used in clinical practice include:

• Whole blood. Rarely used.
• Packed cells. Used in major haemorrhage or treatment of anaemia. Can be stored at 5°C for approximately 30 days. Increases Hb by 1 g/dL per unit transfused.
• Human albumin (5 or 20%). Main use is in hypoproteinaemic state, e.g. nephrotic syndrome, ascites in chronic liver disease. Also used as a plasma substitute, e.g. in burns.
• FFP. Contains all the clotting factors in plasma. Dose is 10–15 mL/kg. Main indications for use include reversal of warfarin, DIC, massive transfusion and liver disease.
• Cryoprecipitate. Contains FVIII, FXIII, fibrinogen and von Willebrand’s factor. It is pooled from 10–20 adult donors. Used in hypofibrinogenaemia (<1 g/dL), massive transfusion, DIC and haemophilia.
• Platelet concentrates. Stored at room temperature for 5–7 days. Main indications are for massive transfusions, DIC and thrombocytopaenia with active bleeding or in a thrombocytopaenic patient requiring surgery.

Alternatives to the use of stored blood include:

• Autologous transfusion. This includes preoperative autologous donation (blood is donated by the patient prior to surgery for that same patient), acute normovolaemic haemodilution (blood is removed immediately preoperatively; this is replaced with crystalloid) and perioperative red cell salvage (includes blood from drains being re-transfused, e.g. after knee replacements and cell salvage intraoperatively).
• Pharmacological methods. These include aprotinin (a serine protease inhibitor that inhibits fibrinolysis and has been shown to reduce blood loss in cardiac surgery), tranexamic acid (inhibits fibrinolysis), desmopressin (increases factor VIII – used in mild haemophilia and von Willebrand’s disease) and erythropoietin (can be used to stimulate red blood cell production preoperatively).
• Blood substitutes. Largely in the research stage. However, some oxygen carrying fluids such as fluorinated organic compounds, have been tested.
• Plasma substitutes. Include gelatin solutions (Gelofusine, Haemaccel). They are used to restore circulating volume until blood becomes available.

Clinical aspects of blood transfusion

1. The patient’s ABO and Rh groups are established.
2. Each unit of group compatible blood is then cross-matched against the recipient’s serum.
3. Minor incompatibilities may occur and require further cross-matching.
4. If blood is required urgently, O negative (universal donor) may be given in an emergency with comparative safety.
5. ‘Group and save’. In some operations, transfusion is unlikely but occasionally possible. Blood is taken preoperatively and grouping assessed. The serum is retained in the laboratory and blood is cross-matched as required.
6. For some operations, blood should be immediately available. Blood is grouped, cross-matched and available on the day of surgery.
7. Mistakes with mismatched transfusions often have serious and occasionally fatal consequences. To avoid mistakes, blood specimens sent to the laboratory must be carefully labelled with the name, date of birth and hospital unit number of the patient.
8. Each unit of blood subsequently transfused must be carefully matched to make sure that the label of the bag of blood corresponds with the name, blood group and hospital number of the patient.

Complications of blood transfusion

Acute

Haemolytic transfusion reaction

This is secondary to ABO incompatibility and is usually due to human error. Patient may have a temperature, shortness of breath, rigors, loin pain, hypotension and oliguria. Jaundice and haemoglobinuria may occur. If the patient is unconscious, a pyrexia and a drop of BP >10 mmHg should cause concern. Initial management includes ABC, stopping the transfusion, checking the identity of the patient, checking blood group of patient and donor blood group, taking blood for haemolytic screen and clotting. Management involves maintaining a diuresis with fluids and mannitol. ARF may occur and should be treated appropriately. Reaction to other red blood cell antibodies is not as dramatic.

Allergic reaction

Itching, skin rashes and urticaria may occur. Slow down or discontinue transfusion and administer antihistamine. Rarely anaphylaxis may occur.

Transfusion related acute lung injury (TRALI)

Similar to ARDS. Due to agglutination of WBCs due to HLA antibodies in the donor plasma (usually occurs in multiparous women).

Non-haemolytic febrile transfusion reaction (NHFTR)

Fever or rigor. Due to prior sensitization to WBC antigens, e.g. after pregnancy or previous transfusions (possible to get leukocyte depleted blood). Managed by slowing transfusion and giving paracetamol.

Bacterial sepsis

Uncommon.

Circulatory overload

Blood should be given slowly in the elderly or those in heart failure. Each unit of blood may be given with a small dose of furosemide.

Hypothermia

Hyperkalaemia

Delayed

Delayed haemolytic transfusion reaction (DHTR)

Occurs when a patient has been exposed to red blood cell antigens, e.g. previous transfusion. After 5–10 days an immune response develops and the transfused cells are destroyed. It presents with fever, anaemia, jaundice and haemoglobinuria.

Iron overload

Graft versus host disease

Rare. Donor lymphocytes engraft into the recipient’s marrow. They then recognize the recipient as foreign and cause an immunologic reaction.

Immune modulation

Increased risk of infection and increased risk of tumour recurrence.

Infections

Rare. All blood is checked for HBV, HCV, HIV and syphilis. Bacterial contamination of blood products can occur.

Post-transfusion purpura

Rare. Occurs 5–10 days and is due to HLA antibodies in the recipient. Presents with low platelets and bleeding. May be treated with i.v. steroids and immunoglobulins.

Massive blood transfusion

This is defined as a transfusion equal to or greater than the whole blood volume in <24 h. Specific complications include thrombocytopaenia, decreased coagulation factors, hypothermia, hypocalcaemia due to citrate-binding, hyperkalaemia and acidosis. In major trauma, it has been shown that transfusion of blood, FFP and platelets in a 1:1:1 ratio is associated with improved survival.

Fluid and electrolyte balance

The basic principle of fluid and electrolyte balance is that which is lost must be replaced.

Water loss in a normal individual is approximately 2500 mL/day (urine = 1–1.5 L, faeces = 100 mL, sweating = 600 mL and water vapour via breathing = 400 mL). In the uncomplicated patient, 2.5–3 L of fluid replacement is adequate. In the postoperative patient these losses may be much greater. Sources include sweating (10% increase in insensible losses for every 1°C rise in temperature) and GI losses from vomiting, diarrhoea and fistulae. In addition to water replacement, it is important to consider electrolyte replacement, mainly Na+ and K+. The loss of Na+ is around 100 mmol/day (mainly from the urine) but 40 mmol/day is lost in sweat (therefore it is more in the febrile patient). Some 80 mmol/day of K+ is lost in the urine and a small amount in the faeces (more if diarrhoea). Generally GI losses can be replaced with normal saline. The amount of ‘fluid’ a patient needs should be based on their size. This can be calculated either from the 4/2/1 (4 mL/h for the first 10 kg; 2 mL/h for the second 10 kg and 1 mL/h for every kg thereafter = hourly rate of fluid); or 100/50/20 rule (100 mL/kg for first 10 kg; 50 mL/kg for next 10 kg and 20 mL/kg thereafter = 24 h fluid requirement). In a 70 kg man this is around 2.5 L/day or 110 mL/h. It is also important to replace electrolyte losses. These can be calculated as 1–2 mmol/kg per day for Na+ and 0.5–1 mmol/kg per day for K+.

Before understanding the effects that different fluids have on a patient’s circulation, it is necessary to understand a few important physiological points:

• In a 70 kg man, the total body water (TBW) is 42 L
• image or 28 L is intracellular fluid (ICF)
• image or 14 L is extracellular fluid (ECF) – image of this or 10 L is interstitial and image or 4 L is plasma
• A small amount of fluid is termed transcellular and is not exchangeable, e.g. CSF, aqueous humour.

Crystalloid and colloid

Intravenous fluids can be divided into crystalloids and colloids.

Normal saline

0.9% saline solution with 154 mmol of sodium and chloride. pH 5.5. This fluid is isotonic and therefore stays in the ECF (i.e. is distributed over 14 L). Therefore, as the intravascular part is only 3.5 L, only 25–30% of a litre of fluid remains in the intravascular compartment.

5% dextrose

The added glucose is metabolized (giving 837 kJ/L of energy). This means the fluid is no longer isotonic but hypotonic and thus distributes over the TBW. As plasma only contributes 7–8% of the TBW, only 7–8% of a litre of 5% dextrose remains intravascular.

Dextrose saline

Contains image the amount of sodium of normal saline, i.e. 30 mmol/L and 4% dextrose.

Hartmann’s solution

This has a chemical composition closer to plasma. Contains 131 mmol Na+, 112 mmol Cl−, 5 mmol K+, 2 mmol Ca2+ and 28 mmol HCO3−.

With this in mind, a suitable regime of postoperative fluids may include:

• 1 L normal saline and 2 L of 5% dextrose with 20 mmol KCl in each of the bags. Each bag is given over 8 h and provides 3 L of fluid, 154 mmol Na+ and 60 mmol K+.
• 3 L dextrose saline with 20 mmol KCl in each bag. Each bag is given over 8 h and provides 3 L of fluid, 90 mmol Na+, 60 mmol K+. This regime is better in the first 24 h postoperatively as the adrenal response to surgery/trauma tends to conserve sodium.
• 1 L Hartmann’s fluid (no K+ added) with 2 L of 5% dextrose each with 20 mmol KCl. Each bag is given over 8 h and provides 3 L of fluid, 131 mmol Na+ and 45 mmol K+. This is a good regime after surgery due to lower sodium and lower potassium (K+ is released with tissue damage during surgery, thus requirements are lower).

Fluid and electrolyte depletion

Surgical patients may suffer large losses of fluid and electrolytes as part of the disease process, operation or postoperative complications. In addition to obvious losses, e.g. vomiting and diarrhoea, fluid may be lost into ‘new’ spaces resulting from the disease process, e.g. the intestine during paralytic ileus, the peritoneum in peritonitis, the retroperitoneum in acute pancreatitis or intracellular shifts in shock. These losses are called ‘third space’ losses and must be promptly replaced, as the problems they cause are just as important as external losses. These fluids are eventually reabsorbed and care must be taken that circulatory overload does not occur.

Management of Na+ and K+ imbalance

Hyponatraemia (i.e. low Na+)

In a surgical patient, this is usually due to water overload and results from administration of inappropriate amounts of 5% dextrose. If the hyponatraemia associated with fluid overload is mild, it is best treated by restricted fluid intake, avoiding the administration of saline, and giving furosemide i.v. to force a diuresis. Electrolytes should be checked twice daily. Hyponatraemia is associated with symptoms, e.g. confusion, convulsions, coma, if the Na+ falls below 120 mmol/L. In hyponatraemia with hypovolaemia, saline should be given.

Hypernatraemia (i.e. high Na+)

This is uncommon in the surgical patient. It may occur during dehydration and in the postoperative period if too much saline is given at a time when aldosterone secretion is high and sodium is being conserved. Rarely it may be caused by Conn’s syndrome (→ Ch. 11). If the cause is dehydration (i.e. clinically dry with low CVP and oliguria), the patient will need water replacement, whereas in the postoperative period with normovolaemia, sodium restriction is required.

Hypokalaemia (i.e. low K+)

Preoperatively, this may be due to diuretic therapy, diarrhoea, fistula or excessive mucus loss from a villous adenoma of the rectum. Postoperatively it is usually due to inadequate K+ replacement. It may occur with pyloric stenosis (with an associated metabolic alkalosis). Symptoms include muscle weakness, cardiac arrhythmias (T wave flattening on ECG) and paralytic ileus. Treatment is by K+ replacement but this should not exceed 15 mmol/h as cardiac arrhythmias may arise with high infusion rates.

Hyperkalaemia (i.e. high K+)

Preoperatively, this may be due to CRF, crush injuries or absorption from massive haematomas. Massive transfusions of stored blood may also cause hyperkalaemia. Postoperatively, it is usually due to excessive administration and is usually asymptomatic. A K+ above 7 mmol/L is an emergency. Intravenous insulin and glucose should be given and the K+ checked. ECG changes include elevated T waves. If ECG changes are marked, calcium gluconate should be given i.v. Other methods of reducing the serum K+ include calcium resonium orally or rectally, and, if renal function is compromised, dialysis.

Acid–base balance

Abnormalities of acid–base balance usually occur in seriously ill patients and include:

Metabolic acidosis

Severe tissue hypoxia, e.g. septicaemia, hypovolaemia or cardiogenic shock; renal failure; diabetic ketoacidosis; and after aortic surgery when the clamp is removed. The patient compensates by rapid deep respiration to ‘blow off’ CO2. Excretes acid urine. ABGs show pH ↓, HCO3 ↓, PCO2 ↓. Management involves treatment of the underlying condition. Bicarbonate infusion may be necessary in severe cases.

Metabolic alkalosis

This occurs with prolonged vomiting or nasogastric aspiration. Pyloric stenosis. In order to compensate, the kidney conserves hydrogen ions at the expense of K+ excretion. ABGs show pH ↑, PCO2 ↑. Low K+. Treatment is by rehydration with normal saline with potassium supplements and treatment of the underlying condition.

Respiratory acidosis

This results from CO2 retention. After surgery, this is usually due to severe chest complications, e.g. atelectasis from sputum retention or respiratory depression due to narcotics. Respiratory acidosis is compensated for by H+ being excreted by the renal tubules and HCO3− being reabsorbed. ABGs show pH ↓, PCO2 ↑. Treatment is of the underlying cause.

Respiratory alkalosis

Hyperventilation due to anxiety. Excessive mechanical ventilation. Compensation occurs by renal excretion of HCO3−. ABGs show pH ↑, PCO2 ↓. Treatment is of the underlying condition.

Nutritional support

Poor nutrition results in increased postoperative morbidity and mortality. Poor wound healing occurs and there is a reduced resistance to infection. General examination of the patient will show evidence of weight loss, e.g. general appearance, loose skin folds. The patient will often be aware of how much weight has been lost and over what time period.

Causes of malnutrition

• Increased catabolism, e.g. sepsis, major surgery with complications
• Increased losses, e.g. chronic liver disease with loss of albumin, protein-losing enteropathy
• Decreased intake, e.g. dysphagia, vomiting, general debility
• Decreased absorption, e.g. intestinal fistulae, short bowel syndrome
• Other causes, e.g. major trauma, chemotherapy, radiotherapy.

Indications for nutritional support

Most patients requiring surgery are well nourished and will stand a few days starvation. They will recover from surgery sufficiently to resume eating before they become malnourished. Some patients will be clearly malnourished prior to surgery, while others may develop complications that delay resumption of normal diet and require parenteral nutrition. Others may have conditions, e.g. short bowel syndrome, which require long-term or permanent nutritional support.

Other indications for nutritional support include:

• Preoperatively in malnourished patients
• Postoperatively in malnourished patients and those who develop malnutrition because of complications
• Patients with sepsis or major postoperative complications
• Patients with fistulae
• Patients with chronic liver disease
• Patients undergoing chemotherapy or radiotherapy for certain tumours
• Patients with short bowel syndrome or malabsorption syndrome.

Evaluation of nutritional status

1. History: duration of illness, weight loss, change in appetite, dietary habits
2. Physical examination, general appearance, loose skin folds, loss of skin contours over bony prominences, muscle wasting, peripheral oedema
3. Weight: in relation to height
4. Anthropometric measurements, e.g. triceps skin fold thickness
5. Laboratory tests, e.g. Hb, serum albumin, serum iron.

Administration of nutritional support

Oral nutrition

This is the most efficient, least expensive, most pleasant and safest route for the patient. If the GI tract is available and the patient able to take oral nutrition, then this method is the most appropriate. Liquidized food, Clinifeed or supplements may be given this way.

Enteral nutrition

This is used for patients with a functioning small bowel unable to take nutrients by mouth, e.g. those who are seriously ill, unable to swallow or have a mouth lesion, e.g. herpes.

Fine-bore NG tubes

Liquidized food, Clinifeed or supplements are given via a tube passed via the nose into the stomach.

Surgically created gastrostomy or jejunostomy

These are appropriate for long-term enteric feeding.

In both the above methods the feed is dripped slowly into the GI tract. Bolus feeding should be avoided as it gives marked diarrhoea and if given via a nasogastric tube in large volumes, may result in regurgitation and aspiration pneumonia.

Complications

Complications of enteral feeding depend on the route of administration and the enteral feed itself. They include:

NG feeding

Removal, blockage, aspiration, reflux, vomiting, diarrhoea, hyperglycaemia.

Gastrostomy/jejunostomy

Pain, bleeding, peritonitis, infection, blockage, diarrhoea, hyperglycaemia.

Parenteral nutrition

This is used where GI function is inadequate and nutrition is administered via the venous system.

Peripheral line

Short-term feeding (up to 5 days) may be given via drip in a peripheral vein. Solutions used with this method must be of a special type, which causes little thrombophlebitis. This method may be used preoperatively for patients with malnutrition of moderate degree for which oral nutrition is unsatisfactory, e.g. malignant strictures of the oesophagus.

Central line

This is the most appropriate route and is used for total parenteral nutrition (TPN). For short-term use, a percutaneous internal jugular line may be used. For longer-term and permanent nutrition, a tunnelled subcutaneous line (Hickman or Broviac) should be used. Hypertonic solutions are infused via the catheter into a large-bore vein with good flow to prevent thrombophlebitis.

Total parenteral nutrition (TPN)

This is usually provided in 3-litre bags either prepared in the hospital pharmacy or bought commercially. This provides all the nutrients required for a 24-hour period. Controlled rates of administration are essential and this is achieved either by a special counting device attached to the drip line or via an infusion pump. Any additional fluid and electrolyte to restore losses, or administration of drugs, should be via a separate peripheral line.

Components of TPN

• Calories: these are supplied as a combination of carbohydrate and fat. Most patients require approximately 2000 kcal/day – or more if they have sepsis or burns
• Protein: this is supplied as amino acids. Nitrogen requirements are about 15 g/day but may be as high as 30 g/day in hypercatabolic states
• Water
• Vitamins
• Electrolytes, e.g. Na+, K+, calcium, phosphate, magnesium
• Trace elements, e.g. zinc, copper, manganese.

Monitoring TPN

Blood sugar, U&Es should be checked daily. Until fluid and nitrogen balance is obtained the blood sugar should be monitored 6-hourly by BM stix. LFTs, calcium, phosphate, and FBC should be checked twice weekly. If the patient becomes pyrexial, blood cultures should be obtained. The site of catheter insertion should be dressed twice weekly under aseptic conditions. If the patient develops a pyrexia and no other cause is found, it may be necessary to remove the catheter and send the tip for culture. The catheter should be used for feeding only. Any other substances, e.g. additional electrolytes or drugs, should be given via a separate peripheral line.

Complications of TPN

Catheter related

Pneumothorax or arterial puncture may occur during insertion. If the catheter is not correctly positioned in a large vein but is in a chamber of the heart, arrhythmias may occur. Rarely the catheter may erode through a vessel wall and give rise to haemopericardium. Air embolus may occur when manipulating the line and this should be avoided by keeping the patient supine. Thrombosis of a central vein may occur. Prophylactic heparin 1000 units/L of the infusion is useful prophylaxis.

Metabolic

Too much or too little of components of i.v. feeding may be given. Careful monitoring for the following is required:

• Fluid overload
• Hyperglycaemia
• Hypoglycaemia (may occur if infusion of hypertonic glucose is suddenly stopped)
• Electrolyte abnormalities
• Hepatic cholestasis.

Home TPN

Long-term TPN in ambulatory patients is practicable providing it is properly monitored. Patients with short-bowel syndrome are the most appropriate. The patient or a partner is taught the technique and back-up is provided by a specially trained team able to provide regular biochemical monitoring. A Broviac or Hickman tunnelled central line is used. The feeding solution may be administered overnight and the catheter disconnected to allow activity during the day. Alternatively it may need to be administered throughout 24 h, depending on the patient’s requirements.

Related posts:

Default ThumbnailInvestigative procedures Default ThumbnailGynaecology Peripheral vascular disease Infection and surgery Organ and tissue transplantation Endocrine surgery