Influence of acute renal failure on FPIA rapid serum assay of midazolam and its main metabolite.

We recently developed a simple and fast assay technique, providing the possibility of monitoring of midazolam (M) during sedation. We compared HPLC vs FPIA for the measurement of the sum M plus alpha 1-hydroxymidazolam (OM), its main and pharmacologically active metabolite, in the serum of sedated ICU patients; this activity referred to as M-like. We identified certain patients in whom M-like activity appeared abnormally high in comparison with HPLC assays. Their common denominators were: long-term sedation with M, and seriously impaired renal function. Further, the conjugates of OM (OMG) accumulated in patients with acute renal failure could contribute to the sedation. We compared the metabolic and analytic behavior of M, OM, and OMG in 2 groups of sedated patients either presenting with normal renal functions (group 1) or with a picture of acute renal failure (group 2). Blood samples were assayed by HPLC and by FPIA and analysis was performed before and after hydrolysis of OMG. Before hydrolysis there was a dramatic accumulation of OMG in the patients of group 2, HPLC vs FPIA results were not different within group 1, while in group 2 the FPIA response exceeded that of HPLC. After hydrolysis, measurement by HPLC was greatly increased in group 2, in each group (vs HPLC) and from one group to another, the FPIA signal (the M-like activity) showed a significant increase. It would be important to take OMG into account as a coprotagonist in sedation whenever circumstances predispose to its accumulation.

[Value of transcranial pulsed Doppler in artery carotid surgery. A comparison of clinical, paraclinical and peroperative data]. / Intérêt du Doppler pulsé transcrânien dans la chirurgie carotidienne. Confrontations cliniques et paracliniques des données peropératoires.

Blood flow in the middle cerebral artery was monitored during carotid artery surgery under loco-regional anaesthesia by plexus block in awake patients in order to assess the value of transcranial pulsed Doppler in understanding the embolic or haemodynamic mechanisms of peroperative cerebrovascular accidents. Blood flow changes in the middle cerebral artery ipsilateral to the operated carotid artery were compared with clinical, paraclinical and operative findings. Sixty-two patients were included in the study, 34 with symptomatic carotid artery lesions and 28 with very severe, progressive but asymptomatic stenosis. Thirteen patients (9 with symptomatic and 4 with asymptomatic lesions) suffered one or more neurological events during surgery. The blood flow velocities were studied at different stages during surgery and compared between the two groups-symptomatic and asymptomatic-to try and assess the mean systolic velocities predictive of cerebral hypoperfusion. Three events occurred during carotid artery dissection, 7 at clamping, 3 during clamping; 9 shunts were installed, one of which at the twelfth minute of clamping. A shunt was not installed in 4 cases: two events occurred at the end of the operation (muscle weakness, diplopia), one event occurred during an episode of hypotension, another at clamping which resulted in aborting the operation as transluminal pulsed Doppler suggested an embolism during dissection. Two events were attributed to an embolic phenomenon and 16 to cerebral hypoperfusion. Peroperative middle cerebral arterial flow recording enables detection of an embolism, monitoring of a shunt and the prediction of a neurological event should the mean systolic velocities fall to less than 15 cm/s and the reduction in velocity attain 70% (sensitivity 87.5%, specificity 91%).

[Cervical plexus block for carotid surgery. 313 consecutive operations]. / Bloc plexique cervical pour chirurgie carotidienne. 313 opérations consécutives.

OBJECTIVES: The optimal method for protecting the brain from ischaemia during carotid surgery is still a matter of debate. The aim of this study was to report our early results after carotid surgery performed with cervical plexus blockade in vigilant patients. METHODS: From 1987 to 1992, 313 consecutive operations were performed on the carotid bifurcation (217 males, 96 females; mean age 67 years; age range 41-87 years). Thirteen underwent bilateral operations at a 1 month interval. There were 118 (38%) asymptomatic patients with carotid narrowing greater than 80% and 195 (62%) symptomatic patients including 96 with temporary cerebral ischaemia, 12 with regressive ischaemic events, 37 with cerebral vascular events and 50 with non-hemispheric events. The contralateral carotid artery was occluded in 30 patients (9.5%). Deep cervical blockade of the C2-C3-C4 roots then superficial blockade was obtained with 0.5% bupivacaine. Operations were endartectomy (n = 301; 96%) including 59 (18.5%) with a prosthetic patch, venous grafts (n = 8; 2.5%) and direct reimplantations (n = 3; 0.9%). All neurological complications observed during the 30 days following operation were recorded. RESULTS: At occlusion, neurological events occurred in 40 patients (12.8%) and required the use of a temporary shunt. In patients with a contralateral occlusion such events occurred in 35.5% of the patients. No cases of myocardial infarction were observed and 1 patient died due to a neurological cause, giving a morbidity of 1.6% and a mortality of 0.3%. CONCLUSION: Cervical plexus blockade was shown to be a simple and effective method for carotid surgery allowing good myocardial haemodynamics and a reliable evaluation of tolerance to occlusion.

[Evaluation of anesthetic activity in the operating room. Use of beta relative cost index]. / Evaluation de l'activité anesthésique au bloc opératoire. Utilisation de l'ICR bêta.

OBJECTIVE: To evaluate the anaesthetic activity in the operating rooms using the newly reconstructed RCI beta, or relative cost index beta, a specific tool for analysis of anaesthetic activity and the linked cost. STUDY DESIGN: Prospective multicentric survey. METHODS: All scheduled anaesthetic procedures performed in March 1995 were collected. RCI beta items were entered in a standardized data base. Gender, age group, time of admission to the operating room, time of incision, time of exit from the operating room, and the code number of the surgical or radiological procedure were added on request of the steering committee. RESULTS: Complete responses were obtained from 35 out of the 37 contacted departments. A total of 31,391 procedures were analysed. Only 14% of patients were of ASA class over 2. Anaesthetic practices were comparable between institutions. Only the incidence of special circumstances and techniques was higher in University hospitals. General anaesthesia was the most widely used technique (76.58%). A large proportion (19%) of anaesthetics were given for endoscopy and radiology. More than 87% of patients were monitored postoperatively in recovery areas. There was a lower correlation between the theoretical standard duration and median actual duration of the perioperative period than the operative period (r = 0.54 vs r = 0.81). DISCUSSION: Part of our activity could be described with RCI beta. The obtained data allow a comparison of anaesthetic activity in the operating rooms of different hospitals, departments and units. Further analysis of these data will also provide information about the types of surgical procedures and the level of global activity.

[Serum histamine, osmolality and hemodynamics during aortography]. / Histaminémie, osmolalité et hémodynamique au cours des aortographies.

Translumbar aortic arteriography was carried out in sixteen patients by injecting 77 +/- 16 ml Télébrix 38 (sodium and meglumine ioxitalamate). Cardiac output was measured by thermodilution by means of a Swan-Ganz catheter. Anaesthesia was induced with thiopentone and fentanyl: the patients were under controlled ventilation. Arterial osmolalities at the 15th, 30th, 60th, 120th, 180th and 300th s showed a major increase, statistically significant from the 30th s on. Arterial and mixed venous histamine measured at the same time varied in parallel, showing a significant rise from the 30th s on for the arterial histamine level. The haemodynamic study of 29 injections showed a significant increase in the left and right ventricular systolic work indices, mostly due to an increase in the systolic index. These changes were similar to those seen during isovolaemic haemodilution. Two phenomena were therefore seen after translumbar aortic arteriography: an almost immediate histamine release, followed later by haemodilution.

[Prevention of per- and postoperative myocardial ischemia in non-cardiac surgery by intravenous diltiazem]. / Prévention de l'ischémie myocardique per- et postopératoire en chirurgie non cardiaque par le diltiazem intraveineux.

A controlled double-blind trial was carried out to assess the efficacy and safety of a continuous intravenous infusion of diltiazem in preventing perioperative myocardial ischaemia in patients with coronary artery disease. Sixty-six patients undergoing non cardiac surgical procedures (vascular surgery, n = 37; other, n = 29) were randomly chosen to receive either diltiazem (group D, n = 32); or placebo (group P, n = 34); there was no difference between these groups in the number of patients in each NYHA class (I: 13/16; II: 14/14; III: 5/4) or having had a previous myocardial infarct (20/22). ECG leads CM5 and CL5 were recorded continuously with an ICR 7200 Holter monitor. After starting recording, either placebo or a loading dose (0.5 mg.kg-1) of diltiazem was given, followed by an infusion of 5 micrograms.kg-1.min-1. Anaesthesia was induced by thiopentone and suxamethonium, and maintained with nitrous oxide (50%), fentanyl and either halothane or droperidol. The number of myocardial ischaemic episodes was significantly (p less than 0.05) lower in group D (2 ST depressions in two patients) than in group P (8 ST depressions in six patients, 2 myocardial infarcts and 1 pulmonary oedema). No conduction disturbance was observed; the lowest cardiac frequency was found in group P (32 b.min-1). Systolic and diastolic arterial blood pressures were lower in group D than in group P, but no difference was found in heart rate and rate-pressure product.(ABSTRACT TRUNCATED AT 250 WORDS)

[Evaluation of direct theoretical cost of passage in anesthesia recovery room]. / Evaluation du coût direct théorique d'un passage en salle de surveillance postinterventionnelle.

OBJECTIVE: To assess the direct cost of a stay in a postanaesthesia care unit (PACU). STUDY DESIGN: Standard cost study based on information gathered from staff and suppliers in accordance with government regulations and recommendations. Results reviewed by a group of anaesthesists. TYPE OF PACU: PACU working in ideal conditions with optimal safety conditions for and accommodation surgical patients). METHOD: Estimation of three cost components: 1) depreciation and maintenance costs of equipment, 2) physician and other staff wages, and 3) variable costs such as drugs and disposable devices. We computed an annual budget for three PACU which was defined according to size (4, 8 or 12 beds) and working hours. RESULTS: Fixed annual costs (staff and equipment) were 1,134,938 FF for a 4 bed room: 3,820,339 FF for an 8 bed room: and 6,481,792 FF for a 12 bed room. Variable costs per stay were 75,43 FF. The cost of a stay in an 8 bed PACU based on a rate of 3,500 stays per year therefore was 1,167 FF (87.0% for staff, 6.6% for equipment, 6.4% for variable costs).

A comparison of ropivacaine and bupivacaine for cervical plexus block.

UNLABELLED: We compared bupivacaine 0.5% and ropivacaine 0.75% for cervical plexus block (CB). Forty patients scheduled for carotid artery surgery were allocated randomly to undergo superficial and deep CB with 30 mL of one of the two anesthetic solutions. We evaluated the onset of anesthetic block; the requirement for supplementation during the surgery; the patients' satisfaction; postoperative pain on a visual analog scale at 1, 2, and 3 h; and the use of paracetamol as a rescue analgesic medication. Arterial blood was sampled immediately and 1, 3, 5, 10, 15, 30, 45, and 60 min after CB for measurements of bupivacaine or ropivacaine concentrations. Patients in both groups had equivalent onset of CB, local infiltration with lidocaine during surgery, and satisfaction scores. In the Bupivacaine group, visual analog scale scores were lower at 2 and 3 h, and the delay before paracetamol administration was prolonged. Observed peak concentrations were larger in the Ropivacaine group (4.25 [2.07-6.59 mg/L] vs 3.02 [0.98-5.82 mg/L]), but time to reach peak concentrations was comparable (5 [1-15 min] vs 5 [0-45 min] in the Ropivacaine and Bupivacaine groups, respectively). We conclude that ropivacaine has no advantage over bupivacaine for CB. IMPLICATIONS: Compared with bupivacaine (150 mg), a larger dose of ropivacaine (225 mg) produces comparable features of cervical plexus block but less postoperative analgesia and larger plasma concentrations. There is no reason to favor ropivacaine in such a case.

Evaluation of benefits related to reduced length of stays in postanesthesia care units.

The study's purpose was to estimate the potential economic benefit of the optimization of postanesthesia care units (PACUs). A simulation model was designed and used to test the economic impact of a reduction of length of stay. For the studied PACU, a reduction of 25% of length of stay is required to yield significant economic results.

Comparison of high-performance liquid chromatography and polyclonal fluorescence polarization immunoassay for the monitoring of midazolam in the plasma of intensive care unit patients.

Midazolam (M) is used as an induction agent for anesthesia. The main metabolite is alpha-hydroxymidazolam (OM), which is pharmacologically active. Use of M for sedation is a recent application, rapidly gaining favor. Monitoring of the level of sedation is fundamental in that an excessive and prolonged effect is associated with the risk of complications. Thus, it was felt both necessary and useful to measure circulating M levels. We compared a high-performance liquid chromatography (HPLC) assay with fluorescence polarization immunoassay (FPIA) for the measurement of M in the serum of 138 sedated patients in the intensive care unit (i.e., 179 samples). Response of the OM was also assessed. The degree of crossover of the metabolite was between 76.8 and 32.7%. The equation of the regression line for sigma HPLC (i.e., the sum M + OM) versus FPIA was TDx = 1.1585 sigma HPLC + 143.42 (R = 0.966). The 95% confidence interval for the slope was 1.1551, 1.1619. The regression slope differed significantly from 1 (p < 0.001) and shows that FPIA measurements overestimated concentrations obtained by HPLC on the order of 19%. The discrepancy between the two techniques was all the more notable when concentrations were > 1,000 ng/ml. The relative selectivity of Abbott industrial reagent in terms of benzodiazepines leads to the identification of what might be called a midazolam-like (M-like) activity covering both M and OM. The development of a global FPIA method for measurement of this M-like activity in sedated patients provides a satisfactory solution to the question raised.