Effects of halothane and isoflurane on transient renal dysfunction associated with infrarenal aortic cross-clamping.

Aortic cross-clamping for reconstructive aortic surgery is associated with impairment of renal function. Halothane or isoflurane was used to assess the influence of volatile anesthesia on renal hemodynamics during aortic surgery. Nineteen patients with normal preoperative creatinine clearances who were scheduled for reconstructive aortic surgery were randomly divided into two groups: halothane group (n = 9) and isoflurane group (n = 10). Induction of anesthesia consisted of midazolam, fentanyl, and pancuronium. Anesthesia was maintained with fentanyl and halothane or isoflurane in nitrous oxide and oxygen (50/50). Systemic hemodynamics were similar in both groups throughout surgery. Before aortic cross-clamping, effective renal plasma flow (ERPF) (131I-hippuran clearance) and glomerular filtration rate (GFR) (99Tc-DTPA clearance) were significantly lower in the halothane group (118.4 +/- 25.6 and 19.7 +/- 5.2 mL/min, respectively) than in the isoflurane group (253.4 +/- 51.5 and 44.9 +/- 8.4 mL/min) (P less than 0.05 for both). During cross-clamping, the renal variables were not markedly affected in either group and remained higher in the isoflurane-anesthetized patients (232.9 +/- 47.1 and 49.5 +/- 1.2 mL/min for ERPF and GFR, respectively) than in the halothane-anesthetized patients (132.4 +/- 31.6 and 14.8 +/- 3.7 mL/min, respectively) (P less than 0.05). After aortic unclamping, ERPF increased markedly in both groups (467.8 +/- 122 and 362.5 +/- 57.7 mL/min in the halothane and isoflurane groups, respectively), as did GFR (74.8 +/- 22 and 71.8 +/- 13.1 mL/min, respectively). These results suggest that anesthesia with halothane is associated with transient renal vasoconstriction during abdominal surgery. In contrast, aortic cross-clamping during isoflurane anesthesia was not associated with renal hemodynamic impairment.

[Pulse oximetry and thoracopulmonary surgery]. / Oxymétrie de pouls et chirurgie thoracopulmonaire.

Arterial blood gases are invasive and they provide intermittent information only. On the other hand, pulse oximetry is non invasive, providing continuous monitoring of SaO2 (SpO2). A study was therefore carried out in twelve patients undergoing lung and intrathoracic surgery to determine whether pulse oximetry was a reliable method of monitoring. The SpO2 values obtained using a Physiocontrol Oximeter (Lifestat 1600) were compared with those given by blood gas measurements (SaO2). When ventilation was switched to one-lung ventilation, PaO2 fell in all cases, whatever the method of monitoring, with PaCO2 remaining constant. 46 paired values of SaO2 were compared using linear regression analysis. Correlation between the two methods was good (r = 0.95; p less than 0.001). Pulse oximetry would therefore seem to provide a reliable method of continuous noninvasive and accurate monitoring of oxygenation during lung surgery.

[Myoglobin: an early indicator of myocardial infarction during heart surgery]. / La myoglobine: un marqueur précoce de l'infarctus myocardique au cours de la chirurgie cardiaque.

Plasma myoglobin was measured in 40 patients before, during and after cardiac surgery under cardiopulmonary bypass, in order to study its value as an indicator of intra-operative myocardial damage. Myoglobin levels rose at cannulation, further increased during the operation and reached a peak 2 hours later; they began to decrease 6 hours after surgery and were back to normal 24 hours later. Myoglobin levels from induction of the anesthetics to the 6th post-operative hour were significantly higher in the 8 patients who developed intra-operative myocardial infarction than in the other patients. Thus, myoglobin is an early indicator of intra-operative myocardial ischaemia. An abnormal rise of myoglobin at induction of the anesthetics characterizes a group of patients at high risk of myocardial infarction during surgery.

[Complement activation in extracorporeal circulation. Comparison of nylon versus polyester bubble oxygenators]. / Activation du complément au cours de la circulation extracorporelle. Comparaison d'oxygénateurs à bulles "nylon" versus "polyester".

Complement activation during cardiopulmonary bypass is well known and may influence postoperative morbidity. As nylon can particularly induce complement activation, its influence was assessed by measuring total haemolytic complement and B, C3 and C4 factors, during cardiopulmonary bypass with bubble oxygenators for coronary surgery, comparing "nylon" circuits (20 patients, Bentley BOS 10) versus "polyester" circuits (19 patients, Shiley S 100 A). Complement activation began with induction of anaesthesia and surgical procedures, B, C3 and C4 levels falling significantly (respectively 15, 17 and 20% from baseline values). The alternative pathway was activated before the classical pathway. Complement activation continued during cardiopulmonary bypass, with no more consumption of complement factors (slight variations of about 0 to 3% of the levels found after anaesthetic induction and surgical procedures). No statistically significant difference appeared between the two groups. This suggested that nylon did not significantly increase complement activation during cardiopulmonary bypass. The bubble oxygenator material cannot therefore be considered as a criterion for choosing the type of equipment.

[Effect of positive end expiratory pressure on arterial oxygenation during bronchoalveolar lavage for proteinosis]. / Effet d'une pression expiratoire positive sur l'oxygénation artérielle en cours de lavage bronchoalvéolaire pour protéinose.

To maintain good cellular oxygenation during bronchopulmonary lavage for alveolar proteinosis is often a difficult problem to solve. A case is reported of alveolar proteinosis in whom four lavages were performed. Details of the technique are discussed, as are the problems with expedients used to improve PaO2. The use of a 10 cmH2O positive end-expiratory pressure was useful only during the "in-phase"; in the "out-phase", it worsened the PaO2. PaO2 during lavage in patients with alveolar proteinosis can only be improved by three ways: cancellation of the shunt during lung filling and, during the "out-phase", an increase in FIO2 or pulmonary artery occlusion by a balloon.

[Plasma concentration of fentanyl during and after its administration at constant flow]. / Etude de la concentration plasmatique du fentanyl pendant et après son administration à débit constant.

Using the technique of the radio-immunological estimation with fentanyl-H3, a study was made in sixteen adults anaesthetised by the administration at a constant rate of alfadione and fentanyl, of plasma concentrations of fentanyl during and after anaesthesia. Anaesthesia was induced by the administration of 4.2ml of alfadione and 0.084mg of fentanyl. The maintenance dose was 0.147 ml/kg/hour of alfadione and 2.95 microgram/hg/hour of fentanyl. Five minutes after induction, the concentration of fentanyl was 2.7 microgram/l. The level fell significantly to 2.56 microgram/l at the 45th minute. From this point onwards, it increased regularly up to the 120th minute, when it reached a level of 3.7 microgram/l. When the infusion was stopped, the level first decreased rapidly, the excretion curve then becoming flattened out. At the 120th minute, a level of 1 microgram/l persisted. This study indicates that the administration of fentanyl at a constant rate is not accompanied by a constant blood concentration up to the 120th minute, the point at which the study was terminated. The residual level found after administration and in the absence of any clinical effect implies the need for a reduction in dose at the time of any complementary administration of fentanyl during the postoperative period.

[Constant flow anesthesia using a combination of etomidate and fentanyl]. / Anesthésie à débit constant par l'association étomidate-fentanyl.

In 35 orthopaedic surgery patients (33 adults and 2 children), anaesthesia was obtained using an association of etomidate and fentanyl. Induction was obtained by injection from a syringe of a mixture of etomidate and fentanyl in an average dose of 21 mg for etomidate and 0,08 mg for fentanyl. Anaesthesia was maintained by constant dose of etomidate was 1.29 mg/kg/h and 4.96 microgram/kg/h for fentanyl. The mixture used for both induction and maintenance contained 1.3 mg of etomidate and 5 mg of fentanyl per ml. The results, value, indications and contraindications of this technique are described.