Getting back to normal

Many anaesthetists will have heard complaints from friends or relatives of how long it took to get back to normal after operations. The complaints are often of weakness, lassitude, and an inability to return to or approach their pre-operative levels of activity. The condition has even acquired a label ‘postoperative fatigue syndrome’ and is said to ‘be a common phenomenon and well known to every surgeon’ [l]. Although these workers suggest that the syndrome is related to the severity of surgery and consequent catabolism, an incidence of about 30% has been reported in patients who have undergone uncomplicated inguinal herniorrhaphy [2]. The symptoms are shared with other effort syndromes such as myalgic encephalomyelitis, but it is not clear if postoperative fatigue syndrome is related aetiologically. It is a measure of the success of anaesthesia that whereas in the past attention was focused on pre-operative preparation and intra-operative management, the scope of the specialty now extends firmly into the postoperative phase. Unfortunately, whereas we have introduced effective analgesic regimens the same cannot be said of postoperative nutrition. Traditionally, this aspect of patient care has been the province of the surgeon and his team who, like others including anaesthetists, have failed to appreciate the parlous nutritional state of many patients [3]. This sentiment is supported by a report from the King’s Fund [4] which states that as many as 50% of surgical patients are malnourished on admission to hospital and recommends that staff routinely monitor the nutritional needs of this group of patients. The situation has not been helped by the increasing delegation to kitchen staff of the distribution of meals, formerly the privilege of the nursing staff, and it is known that many patients who could eat, actually eat very little [5 , 61. To what extent does inadequate nutrition before admission to hospital, whilst a patient, or during convalescence at home, affect recovery after anaesthesia and surgery? The relationship between postoperative fatigue, muscle protein synthesis and whole body nitrogen balance has been examined by Peterson and colleagues [7]. In their study of patients undergoing elective open cholecystectomy, protein synthesis, as measured by ribosome concentration and size distribution, was found to be significantly depressed for over 30 days, a longer period than expected. In addition, the subjective fatigue scores, assessed by visual analogue scales, failed to return to pre-operative values by 30 days after surgery in over half the patients. Other evidence of a similar relationship comes from a recent study suggesting that low plasma tryptophan concentrations may contribute to late postoperative delirium in postcardiac surgery patients IS]. Amino acids are more than mere building blocks for peptides and proteins and both glutamine and arginine are known to have specific, crucial roles in tissue repair and the immune response [9, lo]. Although both are ‘nonessential’ their blood concentrations may decrease in catabolic states as demand outstrips supply [ 1 I]. Similarly, the chronic Western dietary deficiency of unsaturated n-3 fatty acids is thought to facilitate the release of cytokines and render cells susceptible to their effects. The requirements for glutamine, arginine, tryptophan and other nutrients during the recovery phase and/or in the presence of specific diseases is not known but may be very different from those required for normal maintenance. Deficiencies of these may increase the likelihood of sepsis, impair tissue repair, and contribute to postoperative weakness and fatigue. In turn, muscle weakness will delay mobilisation, especially in the elderly after hip or knee operations, and contribute to the complications of prolonged bed rest, notably deep venous thrombosis and pulmonary embolism. It will also delay weaning from positive pressure ventilation. Although volatile anaesthetic agents are known to inhibit protein synthesis and secretion [12-141 it would seem that muscle protein synthesis is not reduced by general anaesthesia per se [ I 51. However, following elective abdominal surgery the rate of muscle protein synthesis decreases by 30% at the end of the procedure and by 50% on the third postoperative day, irrespective of whether or not conventional total parenteral nutrition is given [16, 171. In the past it has been considered sufficient to ensure that an adequate nitrogen balance is maintained and that vitamins and trace elements are supplied. This has, indisputably, been a simplistic approach to a complicated problem since so little is known of the nutritional needs of patients under various pathophysiological conditions or during recovery from different types of surgery. It has been proposed that postoperative fatigue might be reduced by preventing the stress response to surgery [l]. Although pain relief by itself does not substantially inhibit the stress response, epidural block has been shown to reduce catabolism in major orthopaedic surgery and to improve nitrogen balance [18]. It has a similar but less well marked effect during abdominal surgery. Maintenance of normothermia has also been shown to reduce urinary nitrogen and 3-methylhistidine excretion after elective hip arthroplasty [ 191 and this group also reported that muscle glutamine concentrations in the cold patients decreased by almost three times those of the normothermic patients. It is known that benzodiazepine withdrawal induces altered sleep patterns which are associated with rapid eye movement (REM) sleep rebound [20]. In hospital, patients may receive benzodiazepines for night sedation, premedication, sedation during investigations and during anaesthesia. Other sedatives in the form of volatile anaesthetics, opiates, phenothiazines and butyrophenones may also be prescribed. It is hardly surprising, therefore, that on drug withdrawal there should be a period of altered sleep with increased REM activity. As a consequence, the likelihood of obstructive sleep apnoea, hypertension and hypoxaemia is increased with