Haemodynamic stability during moderate hypotensive anaesthesia for spinal surgery. A comparison between desflurane and isoflurane.

BACKGROUND: The aim of this study was to compare desflurane and isoflurane for spinal procedures requiring moderate levels of controlled arterial hypotension, when these agents were administered via a semi-closed circuit at 1 l x min(-1) fresh gas flow. METHODS: After ethics committee approval and written informed consent, 20 ASA I or II patients were randomly allocated to receive either desflurane (n=10) or isoflurane (n=10), in O2/ N2O (1:1) for maintenance of anaesthesia. Induction of anaesthesia, fentanyl dosing and volume loading were standardized. Blood pressure was invasively monitored and maintained within a target systolic blood pressure (SBP) range of 80 to 100 mmHg during the study period. Results were presented as medians and interquartiles, and non-parametric statistical methods were used. RESULTS: Patient demographic data, SBP and heart rate prior to surgery, and duration of the procedure were similar between the two groups. During the study period, tighter arterial blood pressure control was maintained with desflurane as compared with isoflurane. SBP was 21.2% (9.5-41.7) of time outside the range 80-100 mmHg with isoflurane and 5.1% (0.6-10.3) with desflurane (P<0.01). CONCLUSIONS: Desflurane, administered via a semi-closed circuit at 1 l x min(-1) fresh gas flow, maintained better haemodynamic stability in spinal surgery requiring moderate arterial hypotension than isoflurane.

[Comparison of infectious complications of long-term and short-term central venous catheterization]. / Comparaison des complications infectieuses des cathéters veineux centraux de courte et de longue durées.

OBJECTIVES: Risk factors for infectious complications of central venous catheters (CVC) were compared between CVC used for short and long periods to identify patients at risk. PATIENTS AND METHODS: A prospective study was conducted over a 6 month period in two general intensive care units (87 patients with short duration CVC) and in 4 medical units (110 patients with cancer or HIV infection for whom long duration CVC was scheduled). The first CVC inserted was followed to withdrawal or for a minimal 3 months. RESULTS: The mean duration of CVC use was 7.5 and 106 days for the short and long duration groups respectively. A CVC-related infection occurred in 6 patients in the short duration group and in 14 patients in the long duration group giving an incidence of 1.0/100 CVC days (95% CI: 0.4-2.0) for the short-duration CVC group and 0.13/100 CVC days (95% CI: 0.07-0.21) for the long-duration CVC group. Intensive care patients with a skin lesion far from the CVC insertion point had a higher incidence of CVC-related infection than patients without a skin infection. Taking into account the indications for CVC, patients with cancer or HIV infection had equivalent risk of infection. For both short and long duration CVC use, parenteral nutrition was found to be a major risk factor for infectious complications. CONCLUSION: Rigorous regular surveillance of nosocomial infections on central catheters should be centered on those inserted for parenteral nutrition.

[Central venous catheters. Prospective surveillance of a hospital]. / Cathéters veineux centraux. Surveillance prospective sur l'ensemble d'un hôpital.

OBJECTIVES: All the central venous catheters (CVC) inserted at the Saint-Antoine Hospital between December 5, 1994 and June 6, 1995 were prospectively studied in order to better define practices in the management of CVC and to determine the rate of catheter-related infections. METHODS: The following data were recorded for each CVC: insertion procedure, clinical data, catheter dressings, removal, catheter-related infections, bacteriological findings. Catheter-related infections were distinguished from probably catheter-related infections and localized skin infections. RESULTS: Among 325 patients, a total of 414 catheters were inserted. At the end of the surveillance period, 350 (85%) had been removed, 43 (10%) were still in place and 21 (5%) were lost to follow-up. Analysis of procedures such as cutaneous disinfection, routine replacement of the i.v. sets or changes of dressings showed wide variations between care units and within the same unit. The overall incidence of catheter-related infections was 0.24 per 100 days of catheterization. Infections occurred 29 +/- 34 days after insertion. Microorganisms responsible for catheter-related bacteremia were mostly Gram positive (84%) and Gram negative (16%). Sixty-two infections (15%) were clinically suspected by physicians, leading to the catheter removal in 84% of cases. Out of the 43 CVC sent to the laboratory, 29 (67%) were negative (i.e., "sterile") in quantitative culture of the tips as described by Brun-Buisson, suggesting that the CVC was unnecessarily removed. Bacteriological analysis ordered by physicians were not always relevant. For example, 76% of CVC received by the laboratory were systematically sent although they were not suspected of infections. Conversely, only 61% of exsudate formation at the insertion site were collected and analyzed. CONCLUSION: This study was designed to recall good guidelines to the hospital staff. Results will lead to the development of a better use of antiseptics and to the implementation of appropriate and standardized procedures to reduce risk infection.

Prevention of hypothermia by cutaneous warming with new electric blankets during abdominal surgery.

We have evaluated the efficacy of new electric warming blankets, which meet the requirements of the international standard for perioperative electrical and thermal safety, in preventing intraoperative hypothermia. We studied 18 patients undergoing abdominal surgery, allocated to one of two groups: in the control group, there was no prevention of intraoperative hypothermia (n = 8) and in the electric blanket group, two electric blankets covered the legs and upper body (n = 10). Anaesthesia duration was similar in the two groups (mean 201 (SEM 11) min), as was ambient temperature (20.5 (0.1) degrees C). Core temperature decreased during operation by 1.5 (0.1) degrees C in the control group, but only by 0.3 (0.2) degree C in the electric blanket group (P < 0.01). Five patients shivered in the control group compared with one in the electric blanket group (P < 0.05). We conclude that cutaneous warming with electric blankets was an effective means of preventing intraoperative hypothermia during prolonged abdominal surgery.

Effect of neostigmine at different levels of mivacurium-induced neuromuscular blockade.

The effectiveness of neostigmine 40 micrograms/kg for antagonism of two different levels of neuromuscular blockade, induced by a bolus dose of mivacurium 0.15 mg/kg, was studied in 45 patients. The patients were anaesthetized with thiopentone, fentanyl, nitrous oxide in oxygen, and enflurane. Neostigmine was administered at either 10% recovery of the twitch height (TH10) at the adductor pollicis muscle (n = 14) or upon reappearance of the first response at the orbicularis oculi muscle (OO1) after train-of-four (TOF) stimulation (n = 16), the latter representing a deeper degree of neuromuscular blockade. Fifteen of the 45 patients did not receive neostigmine (control group). Neostigmine administration at OO1 rather than at TH10 at the adductor pollicis muscle caused reversal of neuromuscular blockade to occur 8 min earlier and shortened the time to reach 25% recovery of the twitch height (TH25) at the adductor pollicis muscle by about 5 min, compared with the control group. However, the time needed to reach a T4/T1 ratio > or = 0.8 was similar in both the early and late neostigmine administration groups, being 9 min faster than in the control group. It can be concluded that there is no advantage in administering neostigmine at profound neuromuscular blockade to achieve clinically adequate recovery (T4/T1 ratio > or = 0.8). However, the time between injection of mivacurium and TH25 may be shortened by using neostigmine at profound neuromuscular blockade, a procedure which may be useful in case of unpredictably difficult intubation, since diaphragmatic movements usually reappear at TH25.

Air embolism during liver resection: an unusual mechanism of entry from a peristaltic pump.

A case of venous air embolism occurring during liver resection is reported. Diagnosis was made early from the continuous recording of pulmonary artery pressure. The aetiology was neither surgical nor an obvious disconnection of a venous line. It was caused by a blockage of the blood filter, resulting in subambient pressure between the filter and a peristaltic pump, leading to aspiration of numerous small air bubbles. The clinical course after replacement of the defective material was uneventful, except for transient postoperative pulmonary oedema.

In vitro "education" on autologous human sarcoma generates non-specific killer cells.

The cytotoxic effects mediated by lymphocytes from cancer patients after in vitro "education" on autologous tumor cells have been investigated. Peripheral blood lymphocytes from three sarcoma patients were cultivated on autologous tumor-cell monolayers and tested thereafter in a micro-cytotoxicity assay against tumor and fibroblast cells. This procedure led to the progeny of non-specific killer cells. As the phenomenon did not occur when the same lymphocytes were co-cultivated with autologous fibroblasts, the generation of non-specific effector cells may have been caused by specific antigenic triggering. The presence of autologous serum during "education" was found to inhibit the manifestation and/or the generation of killer cells. The same serum was without effect when added during the cytotoxicity assay only.