Preoperative medical problems in surgical patients

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.

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Jul 18, 2017 | Posted by in GENERAL SURGERY | Comments Off on Preoperative medical problems in surgical patients

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