Hepatic circulation and hepatic function during anaesthesia and surgery. IV. Halothane anaesthesia.

HEPATIC CENTRO-LOBULAR ~ O S I S is a non-specific lesion related to liver hypoxia. 1-e This lesion depends on the severity and duration of the oxygen deficit. A three-hour period, in healthy dogs, does not produce an injury detectable with the light microscope, 6 while damage is reported after a continuous six-hour period, or after shorter but repeated exposures to hypoxia. 7 However, the presence of cellular damage can be detected as early as one hour after the onset, provided the tissue is carefully studied with the electron microscope, s The prognosis of the hypoxic liver lesion depends on its severity 9 and on the nutritional condition of the liver. 1~ Normal hepatic tissue is capable of complete regeneration even after relatively severe damage, n Centro-lobular necrosis observed after surgery and anaesthesia may be related to liver hypoxia, especially in the presence of metabolic acidosis, t~ Anaesthesia is a factor which may impair the oxygen supply to the liver, Is or it may have a direct '~hepato-toxic" effect. Unfortunately, there is little information on the role of the various anaesthetic agents on the development of liver hypoxia or on the role played by anaesthesia and hypoxia in producing hepatic damage. Haley reported no hepatic damage when halothane was given in hypoxic mixtures, 14 and he later cont~rmed the increased incidence in hepatic damage when chloroform was administered under similar circumstances. 15 There were no circulatory, functional, or arterial blood gas studies in these reports. We have previously shown that the injury produced by chloroform is proportional to the degree of liver hypoxia developed or is associated with its administration, e In spite of this, however, a direct toxic effect is also suggested by the presence of hepatic lesions even in the presence of an ideal oxygen supply. The adverse effect of chloroform on hepatic haemodynamics is related to the length of the periods of administration, 18 to the arterial CO2 tension, 6 to the systemic haemodynamic changes, and probably to the metabolic acidosis often present during its administration. The purpose of this study is to assess the effects of halothane on the hepatic circulation and function under normal conditions, and during hypoventilation or metabolic acidosis, and to compare these results with those of similar experiments under chloroform anaesthesia.