Preoperative and postoperative care

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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
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