[Computer-assisted intravenous anesthesia: value, method and use]. / Anesthésie intraveineuse assistée par ordinateur: intérêt, méthode et application.

Total intravenous anaesthesia (TIVA) is becoming increasingly popular among anaesthetists. It has several advantages, namely each component of the anaesthetic protocol can be independently controlled, and the operating room remains unpolluted with nitrous oxide or volatile anaesthetic agents. TIVA aims to maintain a constant blood concentration of each anaesthetic agent. This means that infusion rates need to be repeatedly altered. A computer calculates theoretical blood concentrations of agent according to a pharmacokinetic model, and drives an infusion device. Only a few programmes have been developed by research teams. No commercial device is available as yet. However, there are several syringe pumps and volumetric pumps which are accurate enough for use in TIVA and which may be controlled by computer. Clinical studies have shown the benefits of TIVA: greater haemodynamic stability, decreased drug consumption, more rapid recovery, and a lesser need for postoperative ventilatory support. The most appropriate agents are propofol and etomidate as hypnotics, alfentanil and sufentanil for opioids, vecuronium and atracurium as muscle relaxants. Etomidate is not recommended for prolonged infusions, because of the risk of adrenocortical suppression. TIVA seems to be attractive for neurosurgery, thoracic surgery, day case surgery, endoscopic procedures, and anaesthesia in remote locations. Unfortunately, it is an expensive technique. Moreover, there is considerable interpatient variability of the drug concentration required for a same clinical effect. Two methods are proposed to decrease this variability: population pharmacokinetic models and Bayesian forecasting. Closed loop systems are still research tools. It is concluded that computer-driven anaesthesia is the equivalent to the vaporizer for volatile agents. However, further clinical studies are needed to determine whether the advantages of this technique outweigh its disadvantages.

[Influence of sampling techniques on blood sodium, potassium and hemoglobin concentration measured by a blood gas analyser]. / Influence des modes de prélèvement sur la natrémie, la kaliémie et le taux d'hémoglobine mesurés par un analyseur des gaz du sang.

A study was carried out to assess the influence of sampling technique on sodium, potassium and haemoglobin blood concentrations measured simultaneously with a bedside blood gas analyser (Ciba Corning 288) and in the central laboratory. Blood samples from forty intensive care unit patients were used to test cight techniques: capillary tubes (Radiometer & Corning), preheparinized syringes (Terumo 2.5 ml, Sherwood 1 and 3 ml, Corning 1 ml) and Radiometer 2 ml) and a conventional syringe (Plastimed) which was rinsed with heparin just before use. Each result was compared with that obtained by the laboratory. For haemoglobin concentrations, the results were underestimated by the bedside analyser with Terumo, Corning, Radiometer and Plastimed syringes. The differences between results varied with the haemoglobin concentration, and precision was low: 38 to 55% of results showed a difference of more than 1 g.dl-1, and 13 to 25% a difference of more than 2 g.dl-1. The results obtained with the capillary tubes and the preheparinized syringes (Sherwood) showed differences independent of the value, as well as higher precision: 13 to 20% of values differed more than 1 g.dl-1, and 0 to 3% more than 2 g.dl-1. The capillary tubes moderately overestimated the haemoglobin concentration (+0.02 to +0.65 g.dl-1) while Sherwood's syringes underestimated it (-0.48 to -0.94 g.dl-1). For the sodium and potassium concentrations, the eight methods gave results similar to those obtained by the laboratory. It is concluded that these modules for bedside biological analysis, when used in optimal conditions, rapidly provide reliable results for some parameters.

[Consequences and prevention methods of hemodynamic changes during laryngoscopy and intratracheal intubation]. / Conséquences et moyens de prévention des modifications hémodynamiques lors de la laryngoscopie et de l'intubation endotrachéale.

In patients ranked ASA 1, laryngoscopy and intubation lead to an average increase in blood pressure of 40 to 50%, and a 20% increase in heart rate. These changes, which are greatest one minute after intubation, last for 5 to 10 min. They are due to sympathetic and adrenal stimulation, which may also result in some arrhythmias. About half the patient with coronary artery disease experience episodes of myocardial ischaemia during intubation when no specific prevention is undertaken. Among the different means available for this, narcotics seem to have a reliable and constant effect, but they may be responsible for postoperative respiratory depression. The protective effect of fentanyl starts at 2 micrograms.kg-1, and is at a maximum at 8 micrograms.kg-1. Lidocaine is the drug used most. Recent studies have questioned its efficacy. In clinical practice, it is particularly effective in preventing the pressor response to tracheal intubation, whatever its route of administration (intravenous or intratracheal), but not the increase in heart rate. Beta blockers with bradycardic, antihypertensive, antiarrhythmic and antiischaemic properties, have been advocated. As opposed to lidocaine, these agents are more effective in preventing the changes in heart rate than the pressor response. Because of their depressor effect on the myocardium, their place still remains to be defined, especially in the cardiac risk patient. Short-acting beta blockers should be preferred. Nitroglycerin is specifically indicated in coronary artery disease. Other agents, such as clonidine or calcium blockers, seem to be less effective or less convenient in preventing the haemodynamic alterations. In clinical practice, prevention will first rely on a sufficient dose of narcotics. In some cases, nitroglycerin or beta blockers may be used so as to decrease the doses of narcotics, without altering their efficacy; however, the risk of hypotension should be constantly borne in mind. If preventing measures have not been taken, short-acting antihypertensive agents (beta blockers, calcium blockers) should be used in patients who develop major hypertension during laryngoscopy and intubation.

Simplification of the SAPS by selecting independent variables.

A series of 950 consecutive admissions to a multidisciplinary ICU were divided into 2 groups (group I = 450 and group II = 500). In the first group, 351 admissions were used to retrospectively create two scores: SAPS.R derived from the 14 original SAPS variables and SAPS.E derived from 22 variables (14 of SAPS plus 8 additional biological variables). Using a multiple logistic regression analysis only 5 variables were retained for SAPS.R and 7 for SAPS.E. In the second group, 446 patients were used to assess prospectively the discriminating power of SAPS, SAPS.R, SAPS.E by comparing the areas under the receiver operating characteristic (ROC) curves. There were no significant differences between the overall accuracies of these 3 scores. Adding biological variables did not improve the accuracy but the number of variables in the original SAPS could be greatly reduced.

[Purpura fulminans and C7 deficiency complicated by Pneumocystis carinii pneumonia]. / Purpura fulminans et déficit en C7 compliqué d'une bronchopneumopathie à Pneumocystis carinii.

A case of meningococcal purpura fulminans is reported in a 22-year-old woman who also suffered from a congenital deficiency in the seventh component of the complement system. This was her third episode of recurrent meningitis. In the course of her treatment in intensive care, the septic shock was cured, but she developed Pneumocystis carinii pneumonia. Histological investigations revealed abnormalities in her T-cell population, with a very low T-helper (CD4) to T-suppressor (CD8) ratio. Laboratory data showed that she did not have any antibodies to HIV.

[Incidence of nosocomial respiratory tract diseases in intensive care units]. / Incidence des bronchopneumopathies nosocomiales en réanimation.

The incidence of nosocomial bronchopneumonia varies according to authors. Several factors contributes to this diversity. Among them is the type of patients, the severity of disease on admission, the ventilation mode, the criteria of nosocomial bronchopneumonia diagnostic. These considerations should be taken in account by clinician interpreting literature results.

[Fatal acute cerebral edema in a diabetic child]. / Oedème cérébral aigu mortel chez un enfant diabétique.

A case is reported of fatal acute cerebral oedema occurring in a 15-year-old child suffering diabetic ketoacidosis. He had severe gastro-enteritis, with a weight lose of 8 kg over a period of 8 days (initial weight = 50 kg). He was admitted in a stupor with pH 7.15, 129 mmol.l-1 natraemia, and 31 mmol.l-1 blood glucose concentration. Blood osmolaity was calculated to be 310 mosmol.l-1. He was rehydrated with 416 ml.h-1 normal saline and 416 ml.h-1 of 1.4% sodium bicarbonate. At the same time a total dose of 75 i.u. of ordinary insulin was given. After 2 h, the patient's condition suddenly worsened with unreactive coma, bilateral fixed mydriasis, respiratory pauses, and impairment of haemodynamic state (heart rate 150 b.min-1, blood pressure 80/50 mmHg). The diagnosis of cerebral oedema with severe intracranial hypertension was confirmed by different investigations. Despite ventilatory support and continued intensive care, the patient died a few hours later. It is concluded that some degree of subclinical brain swelling could be common occurrence during diabetic ketoacidosis, present maybe even before the start of treatment. Such cases of cerebral oedema are often reported, but the pathophysiological mechanisms remain unclear. However, unlike this case, rehydration must be moderate (less than 41.m-2.day-1), especially in case of hyponatraemia. Insulin and sodium bicarbonate must be used with care. Early rigorous clinical and biological monitoring is essential. Treatment should aim at a progressive correction of the metabolic disturbances.

[Tolerance of femoral vein catheterization]. / Tolérance du cathétérisme veineux fémoral.

The femoral vein is a convenient venous access site which has remained relatively neglected since earlier reports of major complications. However, over the last 10 years, its beneficial use for various purposes (mainly haemodialysis) justifies a reexamination of the value of femoral venous catheterization. The ease of femoral catheterization and its complications were prospectively studied in 92 intensive care patients. Of the 113 attempts made by physicians, 75% of whom were inexperienced, 103 (91.2%) were successful. Insertion resulted in 17 (15%) arterial punctures and 5 local hematomas. Seventy catheters were left in place for an average of 8.8 days. No clinical manifestations of thrombosis were observed. Bilateral phlebography was carried out before removal of the catheter in 70 cases; 45 (64%) of these controls were normal. Of the remaining 25 pathological phlebograms, there were 11 (15.7%) fibrin sleeves, 2 (2.8%) partial thromboses of the common femoral vein which could be directly linked to the venous cannulation, and various abnormalities not directly due to the catheterization (superficial femoral vein thrombosis (4), thrombosis of calf or popliteal veins (18]. One case of catheter septicaemia occurred. Microorganisms were present in 15 (18.3%) of 82 catheter cultured tips. Percutaneous catheterization of the femoral vein might therefore be considered as a good venous access route. It can be successfully used by inexperienced physicians. There is no serious risk of injury to surrounding structures and the risks of thrombosis and infection are acceptable in comparison with other routes.

[Continuous monitoring, in the adult, of arterial oxygen saturation during apnea following intubation]. / Monitorage continu chez l'adulte de la saturation artérielle en oxygène durant l'apnée qui suit l'intubation.

Twenty ASA I or II patients were studied to assess the safety of oxygenation for 4 min prior to intubing, so as to prevent the hypoxaemia related to tracheal intubation. The arterialized capillary blood saturation (Spo2) was continuously monitored with a pulse oximeter Nellcor 100 equipped with a finger probe. Patients spontaneously breathed oxygen (FIO2 = 1) while anaesthesia was induced with pancuronium bromide, thiopentone and fentanyl. Following apnoea, ventilation was manually controlled during 4 min (FIO2 = 1). The values of Spo2 were recorded before induction, at the end of the 4 min oxygenation period and after 5 min of apnoea. An arterial blood sample was withdrawn at the end of apnoea and analysed immediately using an OSM 2b hemoximeter. Apnoea was interrupted in case of desaturation below 95%, new arrhythmia or haemodynamic instability (blood pressure +/- 20% of control value). Mean saturation (+/- SD) before oxygenation was 98.6 +/- 1.35%. After oxygenating for 4 min, all the Spo2 reached 100%. After the 5 min apnoea period, no saturation was below 95% (mean +/- SD = 98.89 +/- 1.66); at this time, Sao2 and Spo2 did not significantly differ (p less than 0.001). In one case, apnoea had to be interrupted, because of the occurrence of arrhythmias, unrelated to a blood gas disorder (PaO2 = 225 mmHg; Paco2 = 34 mmHg; SaO2 = 100%; pH = 7.44). This study confirmed the efficacy and safety of oxygenating for 4 min before intubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of a Bayesian method of amikacin dosing in intensive care unit patients with normal or impaired renal function.

Our study was designed to determine the population pharmacokinetic parameters of amikacin in intensive care unit patients and to develop a Bayesian method allowing individual estimation of pharmacokinetic parameters. A two-stage method was used for estimating the population characteristics of the pharmacokinetic parameters. Calculations of optimum doses and dosing intervals were based on individual parameters. Our results indicate that the Bayesian method is capable of estimating the individual pharmacokinetic parameters with no significant bias and good precision. Individualization of amikacin dosage was assessed 70 times in 52 patients. To determine the predictive performance of the method, observed peak and trough levels were compared with predicted values by computing precision, bias, and correlation. The amikacin dosing method was unbiased and showed a high correlation coefficient (r = 0.962) between measured and predicted drug serum concentrations. No significant differences were found between the predicted and observed peak (17.3 +/- 3.5 and 17.3 +/- 3.8 micrograms/ml, respectively) and trough (2.86 +/- 0.93 and 3.08 +/- 1.41 micrograms/ml, respectively) amikacin serum concentrations. Among the 52 patients, wide variations were observed in the pharmacokinetic parameters (Vd = 0.21-0.50 L/kg; t 1/2 = 1.1-22 h) and the daily doses (2.8-42 mg/kg/day).

Plasma concentrations and pharmacokinetics of midazolam during anaesthesia.

Midazolam and 1-hydroxymidazolam plasma concentrations have been monitored and pharmacokinetic parameters of midazolam estimated during anaesthesia induced and maintained by its repeated injection according to two protocols (3 X 0.3 mg kg-1 at 45 min intervals or an induction dose of 0.3 mg kg-1 with maintenance doses of 0.15 mg kg-1 at 30 min intervals). Minimum plasma concentrations of midazolam measured just before each injection were 258.8 +/- 108.4 ng ml-1 for the first protocol and 353.1 +/- 55.2 ng ml-1 for the second protocol; maximum midazolam concentrations, measured 5 min after the last administration, were 1103.1 +/- 237.9 ng ml-1 and 743.0 +/- 103.2 ng ml-1, respectively, suggesting that a continuous infusion of midazolam after a loading dose should be better than repeated injections at keeping the concentration close to the sedative level of 400 ng ml-1. The estimated pharmacokinetic parameters were similar to those already published, except for the beta elimination half-life of midazolam (3.24 +/- 0.90 h for protocol 1 and 3.34 +/- 1.47 h for protocol 2) which was slightly longer than that reported for single dose studies. The comparison of plasma determinations, obtained either by gas-liquid chromatography or by a radioreceptor assay technique, clearly showed that 1-hydroxymidazolam, even after repeated midazolam administration, was not present at a concentration sufficient to affect the overall pharmacological activity of the parent drug.

[Dysautonomia at 2 times in Guillain-Barré syndrome]. / Dysautonomie en deux temps au cours d'un syndrome de Guillain-Barré.

Autonomic dysfunction is described in a 63 year old woman suffering from Guillain-Barré syndrome. Bradyarrhythmias occurred during the convalescent phase, whereas neurologic and respiratory symptoms were improving; they were not related to bronchial aspiration. Their severity and the inefficiency of medical treatment led to the insertion of a demand pace-maker. Cardiac monitoring by the Holter method in severe cases of Guillain-Barré syndrome may detect potentially lethal arrhythmias, that may then be avoided by a demand pace-maker.

Meningitis due to Micrococcus luteus.

We are presenting a new case of meningitis due to the Micrococcus luteus species. This germ was isolated twice in eight days from the CSF of a 57-year old woman. The patient had a ventriculoperitoneal shunt implanted for hydrocephalus following a meningeal haemorrhage. Antibiotic therapy was efficient but the patient died of a recurrent haemorrhage.

A simplified acute physiology score for ICU patients.

We used 14 easily measured biologic and clinical variables to develop a simple scoring system reflecting the risk of death in ICU patients. The simplified acute physiology score (SAPS) was evaluated in 679 consecutive patients admitted to eight multidisciplinary referral ICUs in France. Surgery accounted for 40% of admissions. Data were collected during the first 24 h after ICU admission. SAPS correctly classified patients in groups of increasing probability of death, irrespective of diagnosis, and compared favorably with the acute physiology score (APS), a more complex scoring system which has also been applied to ICU patients. SAPS was a simpler and less time-consuming method for comparative studies and management evaluation between different ICUs.