Anaesthesia for intestinal short circuiting in the morbidly obese with reference to the pathophysiology of gross obesity

Abstract

MANY REPORTS on anaesthesia for grossly obese subjects have been published. 1-6 These reports emphasize the difficulties encountered in the management of obese subjects for anaesthesia and surgery.We have recently had experience with the anaesthetic and post-operative management of 16 subjects who presented for intestinal bypass operations for gross obesity. We shall review the pathophysiology of this disease with particular reference to the cardiovascular and respiratory systems and shall present a teehnique of management which takes cognizance of these problems. The "Pickwiekian syndrome "~ characterized by alveolar hypoventilation, right heart failure and polycythaemia will not be discussed due to its rarity and because we did not encounter a case in this series.Intestinal short circuiting procedures are used to reduce weight in grossly obese patients after other methods have failed. Post-operative pulmonary complications are frequent and show a definite increase as the weight of the patients increases above ideal weight. 7 The mortality rate after upper abdominal operations in obese patients is two and one half times that of the non-obese patient, s Obesity is associated with pathological changes in the cardiovascular system. Hypertension is a common occurrence in obese patients 9 and will diminish with weight reduction. 1~ Backman 11 measured intravascular pressures in nineteen patients weighing 108 to 172 kg. Brachial artery pressures were raised above normal. At rest, mean pulmonary artery pressure and pulmonary capillary venous pressure were also above normal. During exercise, right ventricular pressure, mean pulmonary artery pressure and pulmonary capillary venous pressure increased abnormally as cardiac output increased. Cardiac output increases with increasing weight and may double the predicted cardiac output at ideal weight. 12 Total blood volume is expanded but blood volume on a weight basis is less than normal and is low in relation to total body weight? ~ Blood flow to adipose tissue forms an important fraction of the increased cardiac output because fat is an active metabolic tissue. 11 The increased cardiac work load, elevated systemic and pulmonary pressure, and the enlarged stroke volume lead to muscular hypertrophy of the right and left ventricles. 13 The increased cardiac work-load affects mainly the left ventricle. 14 The anaesthetist, aware of these alterations, must avoid further stress to the cardiovascular system. Infusion of water and electrolytes requires eareful regulation as 10 per cent of these patients may be in congestive heart failure. 9 Similarly the

Postoperative Pulmonary Function in Obese Patients after Upper Abdominal Surgery

“…The postoperative hypoxemia we found was not of greater magnitude than in nonobese patients after similar surgical procedures (DIAMENT & PALMER 1966, KNUDSEN 1970. Obese patients have a low FRC (BEDELL et al 1958), which is further decreased postoperatively (MARSHALL & WYCHE 1972), when the FRC falls below the closing volume (Fox 1975). O n the basis of these facts, an even more marked postoperative hypoxemia was expected in these patients.…”

“…Because of a postoperatively depressed respiratory function in massively obese patients, CATENACCI et al (1961) recommended mechanical ventilation in the recovery room. FOX (1975), on the other hand, preferred immediate postoperative extubation and the institution of intensive cardiopulmonary care, including semirecumbent position, humidification of inspired oxygen, chest physiotherapy and early mobilization of the patients. Our findings indicate that the latter regime leads to satisfactory postoperative recovery, and that mechanical ventilation in the postoperative period is unnecessary in uncomplicated cases.…”

The Perioperative Management of Morbidly Obese Patients (a Surgeon's Perspective)

“…Such patients may have a reduction in plasma volume and a depletion in total body potassium. 28 The latter may have a consequent effect on peripheral nerve conduction and the activity of neuromuscular blocking agents,29 and also on contractility and conduction of the myocardium, rendering the heart more prone to digitalis intoxication and arrhythmias. 30 A small decrease in serum potassium may represent a large deficit in total body potassium.…”

Αξιολόγηση διεγχειρητικού βάθους αναισθησίας με τη χρήση του BIS (bispectral index monitoring) σε ασθενείς με νοσογόνο παχυσαρκία

“…Η αναισθησία για τους super παχύσαρκους ασθενείς είναι πρόκληση για τον αναισθησιολόγο όχι μόνο λόγω της δυσκολίας εφαρμογής διαφόρων τεχνικών που υπάρχει σε αυτούς τους ασθενείς αλλά και λόγω των σημαντικών παθοφυσιολογικών μεταβολών που προκαλεί η παχυσαρκία στα διάφορα συστήματα. Ιδίως στο καρδιαγγειακό και στο αναπνευστικό (279,280) . Ένα άρθρο ανασκόπησης πρόσφατης βιβλιογραφίας αναφέρει ότι πραγματικά δεν υπάρχει ιδανικός τρόπος χορήγηση αναισθησίας για ασθενείς με νοσογόνο παχυσαρκία.…”