616 obstruction
(see figure). The contrast medium rapidly flows via infrahepatic lymphatics caudally and medially along the common bileduct to the periaortic lymphatics, and presumably from there back to the venous system. This observation suggests that communications normally exist between the intrahepatic bileducts and infrahepatic lymph channels and that the two systems share, perhaps in proportions which can be be modulated, the task of excretion from the liver. In biliary obstruction, for example, conjugated bilirubin "regurgitates" from the liver cell into the bloodstream, to be cleared by the kidney instead of the gut. The specific route of regurgitation may well be via the hepatic lym-
phatics. Little attention has been directed
to
the function of the
hepatic lymphatics. They are blithely destroyed during operations on the gallbladder and bileducts. In cirrhosis, where portal lymphatics are grossly distended, this may cause postoperative ascites: suction catheters in the subhepatic space may drain 500-1500 ml of serous fluid per day from such patients, although they did not have ascites preoperatively. In some instances, surgical relief of long-standing biliary obstruction is followed by deepening jaundice. What additional transport functions are involved in this lymphatic system remain to be discovered.
Surgical Services, Massachusetts General Hospital, Boston, Massachusetts 02114, U.S.A., and Department of Surgery, Harvard Medical School
ANDREW L. WARSHAW
Department of Radiology, Massachusetts General Hospital and Harvard Medical School
JOSEPH T. FERRUCCI, JR.
VENTILATORY RESPONSE TO CARBON DIOXIDE IN DEPRESSION et al.l found the ventilatory response to inhalation to be decreased in endogenous depression, and CO2 our results support their findings. We have studied the CO2 sensitivity in 45 depressed persons and in 18 controls (age range 25-62, mean 45) who had no evidence of pulmonary disease on clinical examination. There was agreement on diagnosis obtained by two psychiatrists using the Newcastle rating scale2 in all but one patient. 32 patients had reactive depression (age range 24-63, mean 43.5) and 13 had endogenous depression (32-72 y, 57-4). The CO, response was measured on admission by a modification of Read’s technique.3 The subjects rebreathed for 2.5-7 min into a closed system consisting of a 6 litre bag initially filled with oxygen. Expired end-tidal PC02 (PeC02) was monitored near the mouth by a Beckman LB2 gas analyser. Ventilation was measured by electrical integration of flow-rate to volume through a mercury pneumotachometer. Ventilation (VE) was calculated in 20 s segments and plotted against the mean p eco2 of the segment. The CO2 response was expressed as the slope of the regression linear (&Dgr;VE/&Dgr;PeCO2).1 During the first minute responses are erratic and these values were neglected. The CO2 responses of the endogenous depressed patients (mean 0-33, S.E.M. 0-04) were significantly lower (P
(see figure). The contrast medium rapidly flows via infrahepatic lymphatics caudally and medially along the common bileduct to the periaortic lymphatics, and presumably from there back to the venous system. This observation suggests that communications normally exist between the intrahepatic bileducts and infrahepatic lymph channels and that the two systems share, perhaps in proportions which can be be modulated, the task of excretion from the liver. In biliary obstruction, for example, conjugated bilirubin "regurgitates" from the liver cell into the bloodstream, to be cleared by the kidney instead of the gut. The specific route of regurgitation may well be via the hepatic lym-
phatics. Little attention has been directed
to
the function of the
hepatic lymphatics. They are blithely destroyed during operations on the gallbladder and bileducts. In cirrhosis, where portal lymphatics are grossly distended, this may cause postoperative ascites: suction catheters in the subhepatic space may drain 500-1500 ml of serous fluid per day from such patients, although they did not have ascites preoperatively. In some instances, surgical relief of long-standing biliary obstruction is followed by deepening jaundice. What additional transport functions are involved in this lymphatic system remain to be discovered.
Surgical Services, Massachusetts General Hospital, Boston, Massachusetts 02114, U.S.A., and Department of Surgery, Harvard Medical School
ANDREW L. WARSHAW
Department of Radiology, Massachusetts General Hospital and Harvard Medical School
JOSEPH T. FERRUCCI, JR.
VENTILATORY RESPONSE TO CARBON DIOXIDE IN DEPRESSION et al.l found the ventilatory response to inhalation to be decreased in endogenous depression, and CO2 our results support their findings. We have studied the CO2 sensitivity in 45 depressed persons and in 18 controls (age range 25-62, mean 45) who had no evidence of pulmonary disease on clinical examination. There was agreement on diagnosis obtained by two psychiatrists using the Newcastle rating scale2 in all but one patient. 32 patients had reactive depression (age range 24-63, mean 43.5) and 13 had endogenous depression (32-72 y, 57-4). The CO, response was measured on admission by a modification of Read’s technique.3 The subjects rebreathed for 2.5-7 min into a closed system consisting of a 6 litre bag initially filled with oxygen. Expired end-tidal PC02 (PeC02) was monitored near the mouth by a Beckman LB2 gas analyser. Ventilation was measured by electrical integration of flow-rate to volume through a mercury pneumotachometer. Ventilation (VE) was calculated in 20 s segments and plotted against the mean p eco2 of the segment. The CO2 response was expressed as the slope of the regression linear (&Dgr;VE/&Dgr;PeCO2).1 During the first minute responses are erratic and these values were neglected. The CO2 responses of the endogenous depressed patients (mean 0-33, S.E.M. 0-04) were significantly lower (P
