Preoperative medical problems in surgical patients

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Chapter 10 Preoperative medical problems in surgical patients

Julian Smith, Ming Kon Yii

10.1 Introduction

The most common chronic medical problems in surgical patients are hypertension, ischaemic heart disease, chronic obstructive airways disease, diabetes mellitus and alcoholic liver disease. Other disorders encountered include chronic renal injury, anaemia, cerebral vascular disease and disorders of haemostasis. Many patients have multiple medical conditions, particularly when there is a history of smoking and excessive consumption of alcohol. Many patients have associated depression or anxiety. Thus, when assessing any patient with a surgical problem, an adequate general history and physical examination is essential. Identifying associated medical problems at the first interview gives the best chance for them to be controlled prior to operation.

The aim of management is to make the patient as fit as possible for surgery within the timeframe allowed by the urgency of the surgical condition. Control of concurrent illness will markedly reduce surgical morbidity and mortality. For a patient with chronic bronchitis, stopping smoking several weeks before surgery and a course of chest physiotherapy can turn a procedure from one that is hazardous into one of almost complete safety.

When urgent surgery is required, correction of medical problems must be accelerated and should not delay imperative surgery, especially when the pathology is complicated by haemorrhage, inflammatory or ischaemic necrosis, or septicaemia. The patient’s condition must be improved as rapidly as possible for the forthcoming surgery; cardiovascular and respiratory support has maximum priority. A balance must be struck between the adequacy of resuscitation and the presence of a surgical emergency requiring prompt treatment. Unduly delaying surgery will inevitably lead to multisystem organ failure (MOF). In such patients, early surgery is an integral part of resuscitation and support of associated medical illness.

Assessment of individual systems is considered in detail in subsequent sections. Irreversible system failure may be an indication for organ or tissue transplantation, particularly when only one system is affected.

10.2 Assessing patients for surgery

Progress in anaesthetic and surgical practice has enabled more and more patients, over wider extremes of age, with more and more complex systemic diseases, to be treated by major surgery. Making the patient safe for surgery (Box 10.1) starts with detecting concurrent medical illness in the systems review and physical examination. Evaluation and subsequent treatment of major risk factors are important steps in the reduction of surgical mortality and morbidity. Surgical risk is the probability of mortality or complications associated with surgery or anaesthesia. Risk factors can be related to the procedure or to the patient or both.

Patient-related risk factors to be aware of include:

Procedure-related risk factors may be anaesthesia-related or operation-related and vary with:

The decision to perform surgery depends on weighing the risk factors contributing to mortality and complications against the prospective benefits of surgery in terms of curing disease or alleviating symptoms. In individual patients, other aspects such as relative costs of treatment are not usually considered, but ultimately the costs of surgery compared to its benefits will contribute to determining community expectations and acceptance of surgical procedures.

Of perioperative deaths, about one tenth occur during induction of anaesthesia prior to surgery itself; about one-third occur during operation; the remaining and majority of deaths occur within 48 hours of operation. The most common causes of deaths are cardiac (myocardial infarction and heart failure), pulmonary (pulmonary infections and embolus) and sepsis.

Investigations and diagnostic (screening) tests before surgery

Other tests

In patients aged over 60 years serum glucose, renal function tests and tests of haemostatic disorders — prothrombin time (PT) and activated partial thromboplastin time (APTT), as well as any history of anticoagulant or antiplatelet agent ingestion — should be added (Box 10.2). Preoperative routine tests in those aged over 60 years should include ECG, chest X-ray, liver function tests, renal function tests, prothrombin time, APTT, platelet count and full blood count.

Other preoperative requirements relevant to all patients are preoperative chest physiotherapy assessment and education, preferably stopping smoking at least two weeks prior to operation, and assessment and correction of fluid and nutritional deficits.

10.3 Cardiac disease

Using noninvasive methods, Goldman,1 in the USA, proposed a concise system using nine identified risk factors for estimating the perioperative cardiac risk index (Box 10.3). Patient-related risk factors are: age over 70 years, previous myocardial infarction, heart failure, arrhythmias, ECG abnormalities, aortic stenosis and associated general medical illness. Procedure-related risk factors include intrathoracic, intraperitoneal and aortic surgery and emergency operations. Points are assigned for risk factors and patients are divided into classes with ascending scores. Mortality and morbidity rise steeply and progressively from class 1 to 4.

Major surgery increases oxygen demand and to meet this demand, patients need to increase cardiac output and ventilation. Elderly patients requiring major risk surgery, particularly those with associated systemic disease, should be considered for preoperative exercise stress testing, stress echocardiography and other noninvasive assessments of cardiac function.

These measurements are designed to evaluate cardiac reserve and to identify more precisely the degree of surgical risk. Mortality and morbidity may be diminished by intensive perioperative medical and nursing care.

The risk of surgery is increased in patients with cardiac disease. The risk rises with increasing severity of disease, becoming prohibitive if surgery is performed within six weeks of myocardial infarction. When assessing a patient with cardiac disease, it is necessary to predict the risk to the patient if surgery is not performed or is delayed, as well as the additional risk that the presence of cardiac diseases adds to the procedure.

Urgent operation must be performed regardless of the severity of cardiac disease when conditions such as massive haemorrhage, visceral perforation, strangulating intestinal obstruction or ruptured aortic aneurysm pose an immediate threat to life.

Elective surgery, however, is contraindicated when there is angina of recent onset, unstable angina, recent myocardial infarction, severe aortic stenosis, a high degree of atrioventricular heart block, severe hypertension and untreated congestive cardiac failure. Within three months of an acute infarct (which in 50% of cases is silent), the reinfarction rate after operation is 25%, with a perioperative mortality of more than 50%. The added risk of surgery stabilises at 5% after six months.

The increase in operative mortality is therefore minimal and stable (3–5%) in patients with cardiac disease with New York Heart Association class I or II angina, who have no change in their serial ECG pattern, where more than six months have passed since an acute myocardial infarction and where no clinical evidence of heart failure exists.

Time should be set aside before elective surgery to control concurrent cardiac disease, particularly unstable disease. Time spent in improving the patient’s condition is well spent and will make surgery safer. The introduction of beta-blocker therapy to slow the heart rate, and occasionally myocardial revascularisation, either by percutaneous coronary intervention or by coronary artery bypass surgery, may be necessary to prepare a patient for an essential elective surgical procedure on another system.

Cardiac patients are particularly sensitive to a fall in venous return (and thus coronary perfusion) and to hypoxia, especially when they are also anaemic (Box 10.4). In most cases hypovolaemia is the cause of diminished venous return during surgery but septicaemia, vasodilator drugs and hypercapnia are other causes. Occasionally, the pneumoperitoneum induced for laparoscopic abdominal procedures may reduce venous return. Patients with chronic obstructive airways disease tend to accumulate pulmonary interstitial fluid and, unless care is taken in high-risk patients, diminished pulmonary gas transfer will produce hypoxia and increase the danger of cardiac complications. Postoperative pain leads to increased catecholamine release and an increased incidence of arrhythmias.

Diagnostic and treatment plan

Common cardiac problems

It is important to control certain cardiovascular problems before operation (Box 10.6).

10.4 Respiratory disease

The major risk factor associated with obstructive airways disease is smoking. It can be assumed that smoking more than 20 cigarettes per day for 10 years or more will be associated with significant chronic airways disease. In patients with chronic obstructive pulmonary disease (COPD) the risk of surgery is increased because of postoperative atelectasis, acute infection and respiratory failure. The onset of respiratory failure can be difficult to anticipate, as signs of respiratory difficulty may not be identified before surgery. This is especially the case in sedentary patients. The best clue to the diagnosis is a reduced exercise tolerance.

Patients with chronically damaged lungs tend to retain sodium and water in the lungs after rapid transfusion or minor degrees of over-transfusion. This leads to a gas transfer defect and hypoxia, with alveolar collapse and subsequent infection. These are harbingers of a chain of events that can lead to a seriously ill patient with adult respiratory distress syndrome (ARDS) and progressive MOF.

Emergency surgery in patients with a full stomach adds the danger of pulmonary aspiration, which will dramatically worsen respiratory failure. The risk of respiratory complications varies with the form of surgery that is planned. Upper abdominal incisions, particularly vertical ones, significantly reduce lung capacity in the postoperative period. This is accentuated when pain control is inadequate. Opiates are best administered by constant infusion so that respiratory depression is minimised. Local analgesic techniques such as intercostal nerve blocks are often used to control postoperative pain and to diminish the risk of excessive sedation and underventilation.

History and physical examination

Acute upper respiratory tract infection and bronchitis with evidence of coryza, pharyngitis, tonsillitis or bronchitis with cough and yellow sputum is an indication to postpone elective surgery. Cough is the most common symptom of chronic respiratory disease. Mucoid sputum suggests tracheobronchitis and asthma; yellow or greenish sputum, bacterial infection; foul-smelling sputum, anaerobic infection such as lung abscess; and rusty sputum is typical of pneumococcal pneumonia. Bronchitis is the most common cause of haemoptysis; other causes include tuberculosis, carcinoma and bronchiectasis. Exertional dyspnoea is a further symptom of obstructive airways disease. Exercise tolerance should always be tested if respiratory insufficiency is suspected, especially in sedentary patients and in all smokers. Acute pulmonary infection can produce marked dyspnoea at rest, frequently with pleuritic chest pain. Orthopnoea suggests heart failure, but patients with bronchial asthma often breathe more easily in the sitting position as well. In bronchial asthma, wheezing is paroxysmal and diffuse. With bronchial narrowing, wheezing occurs during expiration and may only be induced on forced expiration or with exercise. A past history of an occupational hazard such as coal dust inhalation, allergies, respiratory illness, including tuberculosis, and thoracic surgery will highlight the need for special preparation before surgery.

Physical signs may be minimal with localised crepitations only. In bronchopneumonia with patchy consolidation, bronchial breathing is frequently absent. Collapse is characterised by moderate impairment of the percussion note with diminished breath sounds, a prolonged expiratory phase and an expiratory wheeze.

Diagnostic plan

Routine tests include posteroanterior and lateral chest X-ray, blood examination for anaemia, sputum culture and ECG.

Spirometry and arterial blood gas estimation are mandatory in patients with evidence of incipient respiratory failure (limitation in exercise tolerance because of exertional dyspnoea and a forced expiration time of greater than five seconds). Testing is also indicated in: patients undergoing major surgery of the upper abdomen or chest; the elderly; patients with cough, sputum, wheezing or asthma; and those with a history of heavy smoking (Box 10.7).

Postoperative respiratory failure is almost inevitable (Box 10.8) if:

Respiratory failure can be precipitated after major or emergency surgery when there is only moderate obstructive airways disease. A FEV1 of 2.0 L will be reduced after operation to below the critical level in most patients subjected to major upper abdominal surgery. In high-risk patients, preparation for surgery should include serial studies of respiratory function to measure the response to treatment, which is based upon stopping smoking and having chest physiotherapy. Bronchodilators are added if pulmonary function tests show significant bronchospasm. Particular care should be taken during and after surgery to prevent pain, underventilation and hypoxia.

Prevention and treatment plan

Patients with chronic obstructive airways disease should stop smoking for at least two weeks, and preferably four weeks, before surgery. The program of preparation includes chest physiotherapy, postural drainage, antibiotics according to sputum culture and for bronchospasm, inhaled bronchodilators. A course of formal preoperative pulmonary rehabilitation may be appropriate

In many patients considered previously unsuitable for elective surgery, improvement occurs, enabling surgery to be performed with relative safety. In patients with severe respiratory damage requiring emergency surgery, postoperative respiratory failure must be anticipated and measures planned for respiratory support to increase the chance of survival. Of major importance is the continuation of postoperative ventilatory support. Intermittent positive pressure ventilation continues until continuous sampling of radial arterial blood shows control of hypoxaemia.

The successful management of established respiratory failure is intimately related to maintenance of cardiac function; particular care should be taken to correct hypovolaemia promptly, but volume loading must be cautious to avoid sudden increases in the venous return that may promote pulmonary oedema. Serial measurement of the atrial pressure by a Swan-Ganz catheter and of cardiac output adds greater precision to volume control. The left atrial pressure is maintained as low as is compatible with normal blood pressure and peripheral perfusion. If the serum creatinine rises, dopamine is administered in small dosage to maintain renal blood flow and urine output (renal dopaminergic treatment). Packed cells rather than whole blood should be used for transfusion.

10.6 Alcoholic liver disease

Alcoholism can be difficult to detect. The amount consumed and length of history are often concealed. In most cases, signs of liver disease can be found that suggest the diagnosis. The degree of liver damage is directly related to the amount of alcohol consumed. Alcoholic liver disease is a common associated problem in both emergency and elective surgical patients. Elective surgery should be delayed in the presence of moderate or severe alcoholic liver disease. In most patients general health and liver function can be much improved by a period of abstinence and chest physiotherapy, especially in those patients who smoke heavily. Emergency surgery often causes a decompensation in liver function in patients with severe cirrhosis, especially with surgical conditions associated with sepsis, bleeding, electrolyte disturbances (hypokalaemia, metabolic alkalosis and acidosis), hypoxia and hypoglycaemia. Sedatives, narcotics, tranquillisers and antibiotics require very careful control of dosage. Most are metabolised and excreted by the liver; portal-systemic venous shunting due to liver disease results in oral agents having an effective 10–20-fold increase in systemic drug delivery, requiring reduction of oral drug dosage.

Complications arising from alcoholic liver disease

There are a number of major problems and complications that can arise in the surgical patient with alcoholic liver disease (Box 10.9). Each is explained in turn.

Malnutrition and vitamin deficiency (especially thiamine) contribute to poor wound healing. The degree to which serum albumin is reduced is the best measure of prognosis in these cases.

Sepsis is increased because of malnutrition, poor hygiene and immunosuppression.

Respiratory failure is common; most patients have associated smoking-induced lung damage. Pulmonary sepsis, increased lung water and a tendency to pulmonary oedema are common complications. Depressed cough reflex and underventilation are common because of delirium, encephalopathy and increased sensitivity to sedatives and narcotics. Congestive cardiac failure often accentuates hypoxia because of increased pulmonary congestion or pulmonary oedema.

Coagulation disorders with a bleeding tendency are frequent. Anticoagulants (heparin and warfarin) are cleared by the liver and are generally contraindicated in liver disease. Poor haemostasis occurs because of reduced prothrombin production by the failing liver, thrombocytopenia secondary to hypersplenism and dilutional coagulopathy from massive blood transfusion. This may result in significant operative bleeding.

Portal hypertension with collateral vein development increases the technical difficulties encountered during abdominal surgery and therefore the technical complication rate. Gastrointestinal haemorrhage from oesophageal varices is an ever-present risk.

Cardiomyopathy with heart failure (as well as ischaemic heart disease) is common in patients with alcoholism, increasing the danger of cardiac decompensation, especially under the conditions of a surgical emergency.

Associated renal insufficiency is common. Hepatic insufficiency and jaundice are additional risk factors in the development of renal injury after surgery (hepatorenal syndrome).

Exacerbation of hepatic insufficiency can follow the stress of surgery, particularly in patients in whom blood loss, infection and water and salt deficiencies are major manifestations.

Delirium tremens is a common cause of acute brain syndrome after surgery. Diagnosis of alcohol withdrawal as the cause is made more difficult if the patient is a secret drinker.

Diagnostic plan

Routine tests (Box 10.10) include blood examination, liver function tests including coagulation screening, serum amylase, chest X-ray and ECG. The level of serum albumin is the best general measure of prognosis. In many cases respiratory function tests are necessary because of significant obstructive airways disease. Abdominal ultrasound, abdominal CT scan and liver biopsy may be indicated when the diagnosis is in doubt.

Treatment plan

Surgery in the patient with alcoholic liver disease is difficult and demanding. Meticulous resuscitation, the correct choice of operative procedure for the surgical problem at hand, the careful timing of surgery and scrupulous technique are of particular importance if surgery is to be completed successfully. These patients are prone to postoperative cardiorespiratory failure, haemorrhage, poor wound healing and sepsis. The general factors in management that require special attention are:

10.7 Chronic renal disease

Chronic renal disease is often subtle in its presentation and it is wise to assess renal function in all patients aged over 40 years, when major surgery is planned. When forewarned of chronic renal disease, elective surgery usually does not need to be delayed. Patients with chronic renal disease are commonly polyuric and acute deterioration in renal function can occur if they become water or saline depleted. Acute renal failure is the most significant complication of chronic renal disease; prevention demands strict attention to fluid and electrolyte balance (especially avoiding dehydration and maintaining a stable level of serum potassium), identification of high-risk patient groups and accurate replacement of blood loss during surgery. Apart from acute renal failure, the main complications of surgery in patients with chronic renal failure are sepsis (including urinary tract infection), poor wound healing, cardiovascular complications such as myocardial infarction and cerebrovascular accident.

Treatment plan

Important aspects of preoperative preparation in patients with chronic renal failure are summarised in Box 10.12. Hypertension and urinary tract infection may need treatment before elective surgery can proceed. Unless absolutely necessary, urinary catheterisation should be avoided. Transurethral prostectomy may be necessary to relieve bladder neck obstruction before elective surgery. Patients with anaemia or renal failure survive with quite low haemoglobin levels, due to an increase in 2, 3–diphosphoglycerate (2, 3–DPG) promoting better transfer of oxygen at the tissue level. Injudicious blood transfusion in a normovolaemic haemodiluted patient may reduce renal blood flow by increasing blood viscosity and can precipitate an exacerbation of renal failure. Thus a haemoglobin level of 8–9 g/dL in patients with chronic renal disease may be adequate for major surgery and not require transfusion. As many drugs are nephrotoxic, particular care must be taken with prescribing (Box 10.13).

As each nephron either functions normally or ceases to function with disease (intact nephron principle), creatinine clearance (Ccr) is an excellent marker of the degree of dose reduction required. If the Ccr is 50% of normal, all drugs cleared by the kidney need 50% reduction in dose. Drugs that are the worst offenders are aminoglycoside antibiotics (gentamicin), analgesics such as phenacetin and NSAIDs, oral hypoglycaemic agents and methoxyflurane. As digoxin is mainly excreted by the kidneys, digitalis toxicity is a common problem in patients with chronic renal failure. Examples of drugs mainly cleared by renal mechanisms are shown in Box 10.14.

In patients not requiring maintenance dialysis and after cautious correction of severe anaemia, management concentrates on preoperative hydration and strict attention to fluid balance during and after surgery. High-risk patients (major vascular surgery, jaundiced and diabetic patients, and those with chronic renal insufficiency) are also given a slow infusion of a solute diuretic during surgery (mannitol 20 g) with careful monitoring of urine output.

Patients with renal impairment present a dilemma with respect to preoperative contrast imaging, owing to the potential nephrotoxicity of the contrast agent. Those patients with mild renal impairment may undergo contrast studies with attention to pre-procedural intravenous hydration, cessation of metformin if prescribed, administration of oral N-acetylcysteine for potential renal protection and contrast dose reduction.

Patients on dialysis are more susceptible to infection and maintenance of the fluid and electrolyte balance is more difficult. Dialysis is reinstituted as early after surgery as haemostasis will allow. Peritoneal dialysis is preferable to haemodialysis if both are available.

Acute tubular necrosis may occur, especially in the high-risk patient, after emergency or complicated surgery. Oliguria in these patients commonly has a correctable hypovolaemic prerenal component to it. Bladder neck obstruction should always be excluded. In patients with a poor response to a fluid load or diuretic measures and a raised urinary sodium, where incipient acute renal failure is likely to be present, preparations for dialysis should be taken as soon as possible (Box 10.15). Extrarenal factors that may contribute to deterioration of renal failure — such as sepsis, fluid and electrolyte disturbances, drug toxicity and inadequate nutrition — should also receive careful attention.

10.8 Haemostatic and haemopoietic disorders

The possibility of a coagulation disorder should be considered in all patients undergoing major surgery. This especially applies to surgery for malignant disease.

Most episodes of excessive bleeding during surgery are due to local surgical or anatomical defects rather than to coagulation disorders; bleeding from a single site without a history of excessive bruising or previous bleeding is usually from an unligated vessel. Bleeding may be primary (intra-operative), reactionary (occurring within 24 hours of surgery, bleeding from vasoconstricted vessels being reactivated as blood pressure returns to normal) or secondary (which occurs after about a week and is due in virtually all cases to septic necrosis of blood vessels). Unless strong evidence exists that a coagulation defect was present or has developed re-operation will be necessary to achieve haemostasis in most instances of reactionary or secondary haemorrhage. Local control of secondary haemorrhage can be very difficult in the presence of local infection.

Sometimes unexpected bleeding can be traced to a generalised defect in haemostasis (Box 10.16). The most common defect of coagulation encountered in surgical practice is prior treatment with oral anticoagulants or antiplatelet agents. Precise diagnosis and correct management require knowledge of the intrinsic and extrinsic pathways to fibrin formation (Fig 10.1) and the formation and the function of platelets. The initial response when a vessel is divided is for it to constrict (Box 10.16). This, combined with platelet aggregation and adherence and plasma coagulation, stops the bleeding. Platelets adhere to an endothelial defect and react with collagen to perpetuate vasoconstriction and produce further platelet aggregation. Exposure of plasma to connective tissue activates specific plasma enzymes and clotting factors, initiating the coagulation cascade. This generates thrombin and ultimately leads to the conversion of fibrinogen to fibrin clot, reinforcing the friable platelet aggregate. Initiation of coagulation also leads to the activation of plasminogen that releases plasmin, a fibrinolytic factor. Plasmin is a natural defence against pathological extension of fibrin deposition.

image

Figure 10.1 Mechanisms of coagulation

From Kumar & Clark, 2005

Clinical assessment

Extensive laboratory investigation for the presence of a bleeding tendency is not required in the routine assessment of an apparently healthy patient. Most haemorrhagic disorders of significance can be suspected during a careful history and physical examination that specifically check for:

The character of the bleeding may also be helpful. Purpura or petechiae suggest a capillary or platelet defect, rather than haemophilia. Large ecchymoses, haematomas and haemarthroses suggest haemophilia. Massive bleeding from a single site after surgery suggests a technical fault rather than a bleeding disorder. In contrast, sudden severe bleeding from multiple sites after prolonged surgery or during obstetrical procedures suggests an acquired fibrinogen deficiency.

The drug history is of particular importance. Recent ingestion of drugs known to influence haemostasis adversely, such as aspirin, clopidogrel and nonsteroidal anti-inflammatory agents oral anticoagulants, quinidine, quinine, thiazides, sulfonamides, phenylbutazone and gold should be checked.

Diagnostic plan

Tests relating to coagulation, platelet function and vascular abnormalities include the following.

Treatment plan

1 Patients on oral anticoagulants or antiplatelet agents

Surgery in patients given coumarin derivatives (warfarin) is relatively safe when the PT is greater than 25% of normal and thus in the range where protection by warfarin against thromboembolism is lost. It is therefore best to stop warfarin well before (five to seven days) elective surgery, convert to heparin or clexane and then stop heparin or clexane just before operation, thus minimising the time when the patient is unprotected from risks of thrombosis and embolisation.

In patients requiring emergency surgery 5 mg of vitamin K intravenously will restore prothrombin levels to greater than 40% within four hours and to normal in 24 to 48 hours. These patients then remain refractory to oral anticoagulants for a week. Immediate and transient restoration to normal PT can be produced by fresh frozen plasma that restores factor II, VII and IX levels lowered by coumarin therapy. The patient can be started on heparin after emergency surgery when haemostasis allows — usually about 24 hours after operation. Heparin is continued until the refractoriness to coumarin can be expected to have resolved, at about one week after surgery.

For elective surgery coumarin derivatives are stopped 5–7 days before surgery and the INR monitored. Heparin or clexane is commenced in the usual anticoagulant dosage and stopped 6–12 hours before surgery. Heparin or clexane is recommenced when haemostasis will allow this with safety. For urgent reversal of heparin, protamine sulfate can be given by slow intravenous infusion. Oral anticoagulants can normally be started again when oral feeding is re-established. The greatest danger of embolic complications in patients taken off anticoagulants is in those with prosthetic cardiac valves, more so than in patients with atrial fibrillation.

Aspirin and/or clopidogrel ingestion is often a factor in perioperative bleeding. Both reduce the capacity of platelets to aggregate. Where possible they should both be stopped at least five to seven days prior to elective surgery. Patients at high risk for arterial thrombosis (e.g. those with a drug-eluting coronary artery stent in situ) should be converted to heparin or clexane and managed as above during the perioperative period. The antiplatelet agents may be recommenced once oral intake has been re-established. For emergency surgery, it may be impossible to cease aspirin and/or clopidogrel in advance of the operation. If excessive bleeding is anticipated or occurs in this situation a platelet transfusion may be required.

4 Consumption coagulopathy

Consumption of clotting factors (including platelets) in the microcirculation may occur in the massively injured patient with tissue necrosis and sepsis, especially when compounded by massive transfusion of banked blood, which is poor in platelets and in labile factors V and VIII (Table 10.2).

Table 10.2 Changes during bank storage of whole blood at 4°C after two weeks

Plasma levels  
Hydrogen ion 25 mmol/L
Citrate 5 mmol/L
Potassium 20–30 mmol/L
Ammonia 1 mg %
Free haemoglobin 20 mg %
Particulate and antigenic debris  
Dead leucocytes — HLA  
Dead platelets  
Plasma protein antigens  
Red cells  
Early loss post-transfusion 20%
2,3–DPG Nil
ATP Very low
Osmotic fragility Increased
Coagulation factors  
Factor V, VIII, IX 10–20% or less
Platelets Nil
Calcium All chelated with citrate
Fibrinogen Relatively normal

Diagnosis depends on the demonstration of a deficiency in labile clotting factors and platelets. Treatment requires expert haematological diagnosis and assistance. In emergency situations of excessive bleeding at operation, steps are:

10.9 Anaemia

As a general rule mild anaemia does not increase the risk of surgery. However, if time permits the cause of the anaemia should be identified before elective surgery. Iron deficiency anaemia is best detected early and treated by oral iron. Patients with the anaemia of renal injury are an exception to the general rule and can cope with quite low haemoglobin levels, due to an increase in red cell 2, 3–DPG that promotes a better transfer of oxygen at the tissue level. However, in all patients the combination of any degree of anaemia with decompensated cardiovascular disease (e.g. angina or obstructive airways disease) warns that intensive perioperative care will be necessary.

Clinical features and diagnostic plan

Preoperative haemoglobin measurement should be performed as a routine examination in all patients. Patients may have significant anaemia but no symptoms if the anaemia has developed slowly over a period of months and the body has compensated for the decreased oxygen-carrying capacity through such physiological mechanisms as increased cardiac output. The signs and symptoms of anaemia vary with its severity and are more marked if the anaemia has developed over a short period.

Symptoms of weakness and tiredness, breathlessness, palpitations and angina can occur with moderate or severe anaemia. Pallor is the outstanding physical sign. Pallor of the conjunctival and palmar creases becomes apparent when the haemoglobin level falls below 10 g/dL. Tachycardia and cardiac failure may accompany severe anaemia.

Classification of anaemia is based upon the size and haemoglobin content of the red cells. These measurements are calculated from the haematocrit, the haemoglobin level and the red cell count. The average size of the red cells (mean corpuscular volume; MCV), the average amount of haemoglobin in each red cell (mean corpuscular haemoglobin; MCH) and the proportion of the total volume of the average red cell occupied by haemoglobin (mean corpuscular haemoglobin concentration; MCHC) are the main red cell indices. With rare exceptions anaemias fall into one of the three categories: microcytic hypochromic, normocytic normochromic and macrocytic normochromic. These correspond to the anaemias of iron deficiency, chronic disease and megaloblastosis.

The differentiation of iron deficiency anaemia from other types of anaemia is rarely difficult. Occasionally, the anaemia of chronic disease, haemoglobinopathies and sideroblastic anaemias may produce a hypochromic microcytic picture on the blood film. The major clinical difficulty in the surgical patient is the separation of iron deficiency anaemia that is secondary to chronic blood loss from the anaemia of chronic disease. The serum iron is decreased in both disorders. The serum ferritin levels are usually decreased in iron deficiency and raised in the anaemia of chronic disease. When doubt exists, total body iron stores can be assessed by marrow examination. Iron deficiency anaemia is the only anaemia with absent marrow iron stores. Reduced oral intake and absorption of iron is a very rare cause of iron deficiency anaemia.

Treatment plan

In the surgical patient, it is often possible to institute iron therapy prior to admission to hospital. Anaemia is thus always best diagnosed and its cause determined during the first office consultation in patients needing elective surgery. For iron deficiency blood-loss anaemia the oral iron therapy begins immediately so that anaemia can be safely corrected prior to surgery. Patients with moderate iron deficiency or haemolytic anaemias do not pose an excessive risk provided the haemoglobin level and the blood volume are adequate (>10 g/dL) and cardiorespiratory function is normal.

In patients with megaloblastic anaemia surgery should be deferred, if possible, until specific therapy such as vitamin B12 or folic acid has repaired the generalised tissue defect. In these cases transfusion alone may not render surgery safe, as protein metabolism of all cells is affected by the vitamin deficiency that causes the macrocytic anaemia. Adequate tissue levels can be achieved with one to two weeks’ oral treatment with vitamin B12 or folic acid or both.

If it is not possible to correct the anaemia in a timely manner, the patient may be given concentrated red cells prior to surgery. A period of three days should be allowed to elapse before operation as the transfused blood will not reach its maximum oxygen-carrying capacity until at least two days following transfusion. This period allows the transfused red cells to accumulate normal level of 2,3–DPG, necessary for efficient delivery of oxygen to the tissues, and allows for plasma dispersal restoring normovolaemia. Elective surgery should seldom be undertaken when the haemoglobin concentration is less than 9–10 g/dL. Patients with longstanding anaemia are able to tolerate a reduced level of haemoglobin better than those who have become acutely anaemic. This tolerance in chronic anaemia is a result of altered 2,3–DPG concentration in the red cells, with a favourable shift in the oxyhaemoglobin dissociation curve to the right.

10.10 Diabetes mellitus

Biochemical testing of the urine should be part of the initial clinical examinations of all patients. Too often the diabetic state is first diagnosed on routine ward testing when the patient enters hospital for surgery. Screening for diabetes begins by examination of the urine for sugar and ketones. Random blood sugar, fasting blood sugar, oral glucose tolerance testing and measuring glycosylated haemoglobin (HbA1c) as an indicator of diabetic control should be performed during the preoperative work-up in suspected or established diabetic patients. Uncontrolled diabetes (HbA1c level >7%) carries a greater risk of infective and other complications after surgery. Good preoperative diabetic control is essential and must be maintained during the postoperative period. Diabetes may be complicated after operation by ketoacidosis if systemic infection supervenes. The usual danger after operation, however, is not hyperglycaemia and ketosis from uncontrolled diabetes but hypoglycaemic reactions from insulin given without adequate carbohydrate intake. In surgical conditions associated with diabetic sepsis surgery must not be delayed unduly. Diabetes is associated with more virulent infections and control of diabetes may not be possible until sepsis is controlled, pus drained and necrotic tissue removed. Surgical conditions such as cholecystitis and appendicitis when associated with diabetes require urgent attention; diabetic gangrene is a surgical emergency if life and limb are to be saved.

Diagnostic and treatment plans

Diabetes mellitus should be brought under control prior to operation (Box 10.17).

Diabetic patients are prone to atherosclerosis at a younger age and should be assessed for the presence of ischaemic heart disease, peripheral vascular disease, hypertension, renal disease and carotid stenosis. An ECG and chest X-ray are indicated in all cases. Renal function is assessed by measuring serum electrolytes and serum creatinine.

Diabetic retinopathy, peripheral neuropathy and autonomic neuropathy are important additional complications that must be checked for in all diabetic patients, as should evidence of infections and fluid and electrolyte disorders.

Mild elevation of blood glucose with detectable glycosuria is acceptable in the perioperative period to ensure that hypoglycaemia does not occur during any period of inadequate carbohydrate intake after surgery. If the patient has been on an oral hypoglycaemic agent, a continuous insulin infusion (CII) or intermittent (every six hours) doses of a short-acting insulin should be substituted if it is anticipated that postoperative feeding will be delayed.

Ideally any operation should be scheduled early in the day, following the normal nocturnal fast. Metformin should be ceased 24 hours prior to surgery due to the risk of lactic acidosis. All other oral hypoglycaemic agents (e.g. sulfonylureas, thiazolidinediones, acarbose) should be ceased when the patient is fasting. Insulin-dependent diabetic patients should have their morning dose of insulin withheld or modified depending on their regimen of insulin and timing of surgery to a short-acting insulin and then be managed by a CII. Diabetes diagnosed in the perioperative period is best managed with insulin delivered as a CII. Treatment with insulin should commence when the blood sugar is greater than 10 mmol/L.

During surgery the blood glucose levels should be monitored half hourly when the patient is being managed with insulin therapy and hourly in those patients not managed with insulin therapy. Intra-operative blood glucose levels should be maintained between 4 and 10 mmol/L and treatment should begin with insulin when the blood glucose level is above 10 mmol/L. The signs of hypoglycaemia are masked in the anaesthetised or sedated patient and hence close monitoring of blood glucose levels is essential. If the blood glucose level falls below 3.5 mmol/L the CII is ceased and a bolus of 50 ml of 50% dextrose should be administered.

Postoperative patients should be maintained on the CII for 48 hours or until eating adequately to maintain the blood glucose levels between 4 and 10 mmol/L. Ongoing glycaemic management is based upon the patient’s preoperative management and glycaemic control as determined by the preoperative HbA1c. Aim for a blood glucose level less than 7mmol/L pre-breakfast and less than 10 mmol/L pre-lunch and dinner. Metformin should be recommenced when there is no evidence of uncontrolled heart failure, sepsis or significant renal impairment and only when the patient is eating. Other oral hypoglycaemic agents can be recommenced when the patient is eating. Patients who were managed preoperatively with insulin therapy should be recommenced on subcutaneous insulin.

In patients with uncontrolled diabetes, diabetic acidosis or coma, the attendant disorders of fluid and electrolytes should be corrected and any sepsis controlled rapidly. Acute surgical conditions may precipitate the development of severe diabetic acidosis and coma; often these conditions need early surgery combined with diabetic control. The diagnosis of diabetic acidosis is confirmed by urine examination and by measurement of serum glucose. Treatment is commenced with isotonic saline infusion. A bolus of insulin and subsequent CII are given, depending upon the degree of ketosis and the age of the patient. Further insulin is given according to the frequent blood glucose determinations. Potassium depletion is common and acid–base disorders may require correction. Monitoring of central venous pressure, plasma osmolality and body weight is often helpful.

A diabetic patient who is unconscious or disorientated is more likely to be hypoglycaemic than hyperglycaemic. Blood sugar estimation will give the diagnosis and insulin should never be given to an unconscious patient unless there is proof of hyperglycaemia. It is safer when in doubt to give 50 mL of 50% dextrose intravenously. This will restore consciousness promptly if there is hypoglycaemia, unless the patient has already suffered serious brain damage or has a concomitant cerebral disorder such as portal-systemic encephalopathy.

10.11 Mental health problems

Organic diseases commonly present with or have associated with them, psychological symptoms and concerns. Symptoms of anxiety are a normal concomitant of any surgical (or medical) condition.

Less immediately apparent is the fact that somatic symptoms are often the first presentation of psychiatric disorders. Physical diseases are respectable, but many patients and some doctors consider that mental health disorders are not. Therefore, patients often present to doctors with somatic symptoms that are used as tickets of entry when their primary disorders are emotional and behavioural. Depressed and anxious patients often present in this way, concentrating on a physical symptom such as weight loss (Ch 7.13) or bodily discomfort rather than the basic depression or anxiety state. If the doctor fails to recognise the underlying psychiatric basis of the presenting symptoms, a fruitless and potentially endless series of investigations may be embarked on in an attempt to find an organic basis for increasingly vague symptoms. Alternatively, the doctor must avoid becoming angry with the patient for what is taken to be evasiveness and failure to cooperate. Discernment, tact and empathy are required from the doctor in coming to the correct diagnosis. Some of the commoner problems encountered are discussed below and their management will often require professional assistance to resolve.

Clinical states

Depressive disorders

Depressed patients often present with physical symptoms such as headache, generalised aches and pain, weight loss, loss of appetite and malaise. The depressed mood and affect of the patient may be obvious. Depression is usually associated with loss of pleasure and slowness of thought, speech and motor activity. However, many depressed patients are also agitated and anxious, which tends to mask the underlying depression and many depressed patients will initially hide or deny this depression. The clinician should be alert to somatic symptoms commonly associated with depression: anorexia, loss of energy, constipation, weight loss and insomnia. Careful enquiry may reveal associated depressive symptoms of loss of interest, inability to concentrate, loss of self-esteem, sadness and loneliness, feelings of guilt, self-reproach and withdrawal and at times a desire to die. Depressive symptoms are often worse in the morning and associated with insomnia and early wakening. They tend to improve during the day and to return in the evening. Suicide is an important and preventable risk in depressed patients. In some cases there may be no obvious cause for depression, but organic illness itself may be a precipitant, both physically and psychologically.

Grief also produces an alteration of mood and affect, but in this instance consisting of sadness appropriate to a real loss. It is important to take a complete social and family history in such instances to identify recent grief-inducing events. Loss of health or function of bodily parts is usually followed by a grief reaction.

Mania and hypomania are states of excessive excitability, elated but unstable mood, agitation and motor and speech hyperactivity. They are seen in the manic phase of bipolar illness. Associated features include impatience, intolerance, disregard of the feelings of others and a bland indifference of practical difficulties. This has considerable implications for management issues such as compliance with treatment.

Organic mental syndromes

Causes of dementia

Diagnostic and treatment plans

Anxiety neuroses and depressive states of psychological origin need to be distinguished as rapidly as possible from organic disease states (e.g. thyrotoxicosis or cancer). It is important to exclude organic disease by appropriate investigations so that the patient can be reassured of their absence. It is even more important to avoid fruitless over-investigation of somatic symptoms when major psychological problems are clearly present. Somatic disorders in which chronic psychological symptoms can be marked include hyperthyroidism and myxoedema, hyperparathyroidism and cerebral tumours. While management of psychological components of illness requires a broad, biopsychosocial approach, of particular relevance to the management of surgical conditions is knowledge of drug therapy.

Drug therapy of psychological problems is often effective but side effects must be carefully monitored. It is important for the surgeon to know the patient’s current medication in preparation for elective or emergency surgery.

Antidepressant drugs

Tricyclic antidepressants (dibenzazepines). Imipramine, amitriptyline, doxepin and derived agents are similar to phenothiazines in structure and have sedative and antidepressant effects. They all block the neuronal uptake of noradrenaline and all show anticholinergic properties.

Tetracyclic antidepressants. Mianserin is used because it is less cardiotoxic and has fewer anticholinergic effects than the tricyclics.

Selective serotonin reuptake inhibitors (SSRIs). Fluoxetine, paroxetine, sertraline and citalopram slow the breakdown of serotonin and enhance cerebral serotonin activity. They take two to three weeks to act and may result in drowsiness, dry mouth, loss of libido, constipation and dizziness.

Serotonin and noradrenaline reuptake inhibitors (SNRIs). Venlafaxine and nefazadone slow the reuptake of serotonin and noradrenaline. Side effects include drowsiness, intense dreaming and abdominal symptoms.

Monoamine oxidase inhibitors. Tranylcypromine and phenelzine, by inhibiting the enzyme monoamine oxidase, increase the concentration of adrenaline, noradrenaline and 5-hydroxytryptamine in the body. Their actions are slow in onset and offset. These drugs are less commonly used now because of their liability to invoke hypertensive crises by potentiation of sympathomimetic agents, including foods with high concentrations of tyramine (cheese, alcohol).

Phenothiazines. These agents are used in combined therapies for depression with schizophreniform features.

Lithium carbonate. This antimanic agent is used alone or in combination with antidepressants in treatment of bipolar syndromes.

10.12 Additional preoperative preparation

Additional preoperative preparation must attend to certain factors that are specific for individual operations and diseases (Boxes 10.1810.24). Patients with ASA classes 3 to 5 will require baseline tests for appropriate systemic disorders.