Pulmonary microvascular injury following general anaesthesia with volatile anaesthetics--halothane and isoflurane: a comparative clinical and experimental study.

Pulmonary microvascular injury has become a recently studied phenomenon that may be responsible for most of the complications associated with the lungs. Thirty patients undergoing partial hemilaminectomy or discectomy due to hernia of nucleus pulposus underwent Tc-99m HMPAO lung clearance as well as Tc-99m pertechnetate lung scintigraphy pre-operatively, and following general anaesthesia with halothane and isoflurane (third, fourth and tenth post-operative days). The results were compared with conventional techniques and haemodynamic parameters during the peri-operative period. In order to demonstrate acute phase changes under general anaesthesia and to perform pathological examinations, 21 New Zealand rabbits underwent radionuclide studies with Tc-99m HMPAO or Tc-99m pertechnetate. Lung biopsies were also performed. Despite no significant differences in any of the conventional diagnostic techniques, Tc-99m pertechnetate lung scintigraphy was performed for both the halothane and isoflurane groups, and Tc-99m HMPAO lung clearance was performed for the isoflurane group pre- or post-operatively. Tc-99m HMPAO lung clearance was impaired significantly in the halothane group on the third post-operative day (half time: 6.4 +/- 1.6 pre-operative and 13.76 +/- 3.3 s, P < 0.001) decreasing to pre-operative levels on the tenth post-operative day. Acute phase exposure to halothane was characterized with extremely abnormal Tc-99m HMPAO lung clearance in rabbits with respect to isoflurane, diminishing to control levels on the third day (half time: 8.7 +/- 86 control and 28.65 +/- 4.6, P < 0.001). Pathological examinations also demonstrated endothelial damage on acute exposure in the halothane group. General anaesthesia with halothane may give rise to alveolar microvascular injury, which generally seems to be underdiagnosed and may lead to serious post-operative complications.

The histopathological comparison of the results of the intra-arterial injections of propofol and thiopentone in rabbits.

The results of injections of propofol and thiopentone intra-arterially are compared in rabbits according to histopathological criteries. Thirteen New Zealand type rabbits are used. Two ml of 2.5% Thiopentone and 2 ml of 1% Propofol are administered to the rabbits under anesthesia. Three days after, their ears are amputated and sent to this pathological blind examination. In both groups, we saw neither a morphological change along the vessel walls nor significant bleeding. But between the groups there was a significant difference about oedema. Consequently, 2.5% thiopentone which is routinely used after intra-arterial administration, may be responsible of the gangrenous change but it is discussable and it makes significant oedema in animal models although propofol does not have this effect.

The effect of propofol on systemic vascular resistance during cardiopulmonary bypass: a comparative study with thiopentone.

30 patients undergoing elective coronary artery bypass grafting surgery were allocated randomly to receive either propofol--2.5mg/kg--(N = 10, Group I) or thiopentone--4mg/kg--(N = 10, Group II) during cardiopulmonary bypass with constant pump flow and temperature. Two groups and another control group-receiving no medication-(N = 10, Group III) were compared with respect to the changes in hemodynamic parameters, especially systemic vascular resistance (SVR). After propofol, SVR decreased from 2489 +/- 302 to 1594 +/- 286 dyn sec cm-5 and remained significantly less than the control values until 16.6 +/- 4 min. after the administration of propofol. Following thiopentone administration, SVR decreased from 2653 +/- 298 to 2162 +/- 279 dyn sec cm-5 and remained so for the following 9.4 +/- 3 min. There were more significant decreases in especially cardiac index, perfusion pressure and SVR in the propofol group compared with thiopentone or control groups. Cardiopulmonary bypass has been shown to be a useful model for studying the isolated effects of anesthetic drugs on hemodynamic parameters. In our study, we tried to discuss the mechanism of the hypotensive effects of anesthetic agents, especially propofol and give an idea about the possible precautions that should be taken.

Effects of perineural opioids on nerve conduction of N. suralis in man.

In this study the effects of agonist acting drugs (morphine sulphate, fentanyl citrate and meperidine hydrochloride) on nerve conduction were studied in 43 healthy young volunteers divided into four groups randomly. According to analgesic equivalent doses, the first group received 2 mg morphine sulphate, the second group 0.02 mg fentanyl citrate, the third group 20 mg meperidine hydrochloride, and as control the fourth group received 2 ml of saline. The latencies, amplitudes of the responses and nerve conduction velocities were obtained immediately before and every 5 min after injections up to 30 min. No significant change was observed within or among the morphine sulphate, fentanyl citrate and saline groups whereas in the meperidine hydrochloride group the amplitudes diminished significantly and this finding was still apparent at 30 min. Four of the cases displayed complete blocks. Nerve conduction velocity did not change in the other 6 cases. The significant decrement of the amplitude of the compound nerve action potential in the meperidine hydrochloride group is probably due to local anesthetic-like action of this drug. Morphine sulphate, fentanyl citrate or saline did not show this effect.

Does remote organ ischaemia trigger cardiac preconditioning during coronary artery surgery?

The aim of this study is to provide biochemical evidence of the occurrence of cardiac preconditioning via remote organ ischaemia on the patients undergoing coronary artery surgery. Eight male patients were randomly allocated into two groups. Blood samples were collected via coronary perfusion catheter immediately before cardiopulmonary bypass (point 0), prior to declamping aorta (point 1) and 5 min after declamping the aorta (point 2) to determine creatinine phosphokinase (CPK), CPK-MB and lactate dehydrogenase (LDH) levels in the control group. A tourniquet wrapped around the right upper extremity of the patient was inflated and deflated twice to perform 3 min of ischaemia separated with 2 min of reperfusion in the preconditioning group. Blood samples were withdrawn as described for the control group. Only LDH levels at point 2 were found to be significantly higher than the control group's. These data implied that preconditioning appeared to protect myocardium by enhancing anaerobic glycolysis.