The tumescent technique for local anesthesia improves the safety of large-volume liposuction (≥1500 ml of'fat) by virtually eliminating surgical blood loss and by completely eliminating the risks of general anesthesia. Results of two prospective studies of large-volume liposuction using the tumescent technique are reported. In 112 patients, the mean lidocaine dosage was 33.3 mg/kg, the mean volume of aspirated material was 2657 ml, and the mean volume of supranatant fat was 1945 ml. The mean volume of whole blood aspirated by liposuction was 18.5 ml. For each 1000 ml of fat removed, 9. 7 ml of whole blood was suctioned. In 31 large-volume liposuction patients treated in 1991, the mean difference between preoperative and 1-week postoperative hematocrits was -1.9 percent

Tumescent technique for local anesthesia improves safety in large-volume liposuction.

Extreme obesity associated with alveolar hypoventilation. A Pickwickian syndrome

It has been demonstrated in an experimental study in swine using the scanning electron microscope that a rebreathing technique utilising minimal fresh gas flowrates significantly improves climatization of anaesthetic gases. Consequently, effects of various anaesthetic techniques on airway climate must be assessed, which covers the need for suitable measuring devices. Basic principles and methods of humidity measurement in flowing anaesthetic gases include gravimetric hygrometry, dew point hygrometry, wet-dry bulb psychrometry, mass spectrometry, spectroscopic hygrometry and electrical hygrometry. A custom-made apparatus for continuous measurement of humidity and temperature in the inspired and expired gas mixtures of a breathing circuit (separated by a valve system, integrated between the endotracheal tube and the Y-piece) is described. Comparative evaluation of this apparatus and the psychrometer was carried out. It could be demonstrated that the apparatus, measuring with capacitive humidity sensors, is more suitable for prolonged use under clinical conditions than the psychrometer. In the second part of the study, climatization of anaesthetic gases under clinical conditions was investigated using fresh gas flowrates of 0.6, 1.5, 3.0 and 6.0 l/min. In the inspiratory limb of the circuit an absolute humidity of 21.3 mg H2O/l and a temperature of 31.5 degrees C were obtained after 120 minutes of minimal flow. Humidity and temperature of inspired air obtained with fresh gas flowrates of 6.0 and 3.0 l/min were found to be inadequate for prolonged anaesthesia. Reducing the fresh gas flow to 1.5 l/min increases heat and moisture content in the respired gases, but conditions are still inadequate for prolonged anaesthesia. Sufficient moisture (> or 20 mg H2O/l) and temperature are obtained under minimal flow conditions after one hour.

Humidity of anaesthetic gases with respect to low flow anaesthesia

This review covers the physiological and clinical implications of lung function during anesthesia and respiratory insufficiency in the postoperative period. We have divided it into 3 main sections: 1) lung function changes induced by anesthesia and surgery, in which the impact on pulmonary mechanics, ventilation/perfusion changes and gas exchange are examined; 2) physiological implications of postoperative respiratory function secondary to decreased alveolar ventilation, development of atelectasis, and interstitial lung edema; and 3) clinical implications of postoperative respiratory failure. In this last section we analyze the current therapeutic modalities available to reduce the incidence of postoperative respiratory failure, as well as related morbidity and mortality.

Lung function during anesthesia and respiratory insufficiency in the postoperative period: physiological and clinical implications

Publisher Summary This chapter presents the adverse effects associated with the use of general anesthetics and therapeutic gases. T. L. K. Rao prospectively studied the incidence of reinfarction following general anesthesia in patients with a history of myocardial infarction. Reinfarction occurred in 14 of 733 such patients (1.9%). The incidence of reinfarction was 5.7% and 2.3% in those patients with 0–3 and 4–6 month-old infarction respectively. Weinsberg showed that patients with mild or moderate hypothyroidism did not differ as a group from controls with regard to the outcome of anesthesia and surgery. Alcoholism is undoubtedly a risk factor in anesthesia, the consequences of which may be coped with, provided the anesthetists do not overlook alcohol-induced functional impairments, notably in the liver, manifestations of alcohol withdrawal, and the pathophysiology of alcoholism with regard to the general anesthetic's pharmacological properties.

General anesthetics and therapeutic gases

Since the state of anaesthesia possesses no intrinsic merit and as far as the patient is concerned merely comes between him and the real business of surgery, the ideal anaesthetic technique would be one of which he was totally unaware. It would have no unpleasant preliminaries or sequelae and certainly would be devoid of all hazards, irrespective of the state of health of the patient, or of the planned operation. For the surgeon, perhaps the ideal anaesthetist would be a modest assistant who provides sound but not timeconsuming or delaying advice before operation, who transforms the patient into a perfect medium for the exercise of his talents without in any way obtruding upon his activities, and then dissolves into the aether, leaving behind a patient who is both none the worse for the anaesthesia and cured by the surgical procedure.

J.C. Stoddart

Papers

Postoperative respiratory failure: an anaesthetic hazard?