[Effects of an additional dose of propofol on intraocular pressure in patients over 60 years of age]. / Effets d'une dose additionnelle de propofol sur la pression intraoculaire chez les sujets de plus de 60 ans.

Changes in intraocular pressure (IOP) and mean arterial pressure (MAP) were studied in fifty patients, ASA 1 or 2, aged more than 60 years and scheduled for surgery of the anterior chamber of the eye. The exclusion criteria were: arterial hypertension, raised IOP, obesity, renal or hepatic disease, treatment likely to alter IOP, and a possibly difficult intubation. The patients were randomly assigned to groups P1 (n = 25) and P2 (n = 25). All were given lorazepam 1 mg orally 90 min before induction, which was carried out with propofol 1.5 mg.kg-1 and vecuronium 0.1 mg.kg-1. Patients in group P1 were intubated as soon as the train-of-four response (TOF) had been abolished. Those in group P2 were given an additional 0.7 mg.kg-1 dose of propofol before intubation. MAP, heart rate and IOP were measured before and after induction, and 1, 2 and 3 min after intubation. IOP decreased after induction, and remained below the baseline values at all times in both groups. MAP had a similar course in both groups up to 1 min after intubation: a decrease after induction followed by an increase after intubation. In group P1, MAP remained above control values 2 and 3 min after intubation, whereas in P2 it remained below. From this study, it can be concluded that using an additional dose of propofol in elderly patients was not useful for avoiding the rise in IOP due to endotracheal intubation. This was all the more so as the haemodynamic effects of such a dose of propofol could have deleterious effects in these patients.

[Transfer hypokalemia induced by norepinephrine infusion]. / Hypokaliémie de transfert induite par la perfusion de noradrénaline.

We report a case of a severe hypokalaemia by intracellular shift of potassium in a sedated and ventilated head trauma patient. The kalaemia which was 3.9 mmol.L-1 at admission in the intensive care unit decreased to 1.3 mmol.L-1 during a perfusion of noradrenaline (0.3 micrograms.kg-1.min-1). Following the decrease of the noradrenaline dose, and administration of potassium, the kalaemia rapidly increased to 5.3 mmol.L-1 carrying a risk of arrhythmia. Therefore, kalaemia and ECG should be closely monitored when the noradrenaline doses are reduced. The causes of transcellular shift of potassium are reviewed.

[Prolonged neuromuscular block after mivacurium injection]. / Bloc neuromusculaire prolongé après injection de mivacurium.

Mivacurium, a new short acting non depolarizing neuromuscular blocker, is metabolized, as suxamethonium, by plasma cholinesterase. Therefore its duration of action is increased in patients with reduced plasma cholinesterase activity. We report a case of prolonged neuromuscular block after an i.v. bolus of mivacurium (0.20 mg.kg-1) in a 69 year-old ASA II woman with an unrecognized cholinesterase deficiency undergoing a lumbar sympathectomy for arteriopathy of the lower limbs. The duration of the block was 6 h and plasma cholinesterase concentrations were very low (540 and 610 UI.L-1), as well as the dibucaine number (16%), which suggests an homozygous enzymatic deficiency. Mechanical ventilation and sedation were continued until spontaneous return of full neuromuscular function.

[Pulmonary embolism of cement during vertebroplasty]. / Embolie pulmonaire au ciment au cours d'une vertébroplastie.

A 62-year-old woman with severe osteoporosis experienced pulmonary embolism by polymethylmethacrylate after percutaneous vertebroplasty. The patient immediately developed respiratory and cardiac distress, and a computed tomographic scan revealed the presence of cement in the pulmonary circulation. Proper techniques can minimize the risk of pulmonary embolism during percutaneous vertebroplasty: adequate preparation of cement and fluoroscopy during the procedure are recommended.

[Monitoring jugular venous oxygen saturation in severe cerebral vasospasm after subarachnoid hemorrhage]. / Monitorage de la saturation veineuse jugulaire en oxygène au cours d'un vasospasme cérébral sévère après hémorragie sous-arachnoïdienne.

Cerebral arterial vasospasm is a major complication of aneurysmal subarachnoid haemorrhage. The conventional treatment of this complication includes haemodilution, hypervolaemia, arterial hypertension and nimodipine. Some patients do not respond to this therapy and require an intraarterial infusion of papaverine and/or a cerebral angioplasty. Transcranial Doppler detects cerebral vasospasm. However it does not provide an accurate metabolic information on the ischaemic status of the cerebral tissue. This article describes the monitoring of jugular venous bulb oxygen saturation to obtain a real time information on the metabolic effect of cerebral vasospasm and its variations after intra-arterial infusion of papaverine.

[Continuous administration of mivacurium for short procedures. Delayed onset and recovery from neuromuscular blockade]. / Mivacurium en administration continue pour des actes courts. Délais d'installation et de régression du bloc neuromusculaire.

OBJECTIVE: To assess the delays of onset and spontaneous recovery from neuromuscular block produced by mivacurium administered by continuous infusion for short procedure requiring a deep relaxation. STUDY DESIGN: Prospective open non comparative study. PATIENTS: Twenty-nine class ASA I and II adults undergoing a stomatological procedure of short duration were included in the study. METHOD: General anaesthesia was obtained with a continuous infusion of propofol, supplemented with alfentanil and N2O-O2 mixture. Neuromuscular blockade, assessed with electromyography of the adductor pollicis muscle, was obtained with mivacurium (150 micrograms.kg-1). After restoration of 5% of neuromuscular transmission, mivacurium was administered by continuous infusion in order to maintain a blockade between 91 and 99%. RESULTS: The delay for decreasing twitch height by 95% was 2.9 +/- 1.0 min. The mean dose for maintenance of blockade was 10.9 +/- 1.5 micrograms.kg-1.min-1. The delay of spontaneous recovery from blockade was 10.2 min, 16.6 min and 21.3 min for obtaining 25, 75 and 95% twitchs respectively. The delay for the twitch increase from 25 to 75% was 6.6 min. DISCUSSION: Mivacurium in continuous infusion provides rapidly a deep and stable neuromuscular blockade followed by a rapid spontaneous restoration of neuromuscular transmission in patients with normal pseudocholinesterases.

[The use of curare-like agents in resuscitation]. / Utilisation des curares en réanimation.

OBJECTIVE: To analyse current data on use of neuromuscular blocking agents (NBA) in the intensive therapy unit (ITU) patients and to propose practice guidelines. DATA SOURCES: We did a Medline search of French and English language articles on NBA administration in ITU patients from 1960 to 1998. Data were also selected from our own collection of articles and books. STUDY SELECTION: Original articles, clinical cases, letters to the editor and review articles were considered. DATA EXTRACTION: Data on pharmacology of NBA in the ITU patient were extracted, as well as data on administration patterns and cost. DATA SYNTHESIS: The indications for myorelaxation in ITU patients include either short term use, as in anaesthesia, or long term administration for facilitation of mechanical ventilation, control of increased intracranial pressure, status epilepticus, tetanus and oxygen demand in case of muscular hyperactivity, diagnostic and therapeutic procedures facilitation. A beneficial effect of NBA on the prognosis of the disease for which these agents have been used is not yet proven. Suxamethonium, because for its short onset time and duration of action, is the agent of choice for endotracheal intubation if myorelaxation is required. Among the benzylisoquinolines, atracurium and besilate of cisatracurium are convenient agents in ITU patients, whereas mivacurium is of no special interest. Among the aminosteroids, pancuronium and vecuronium are the most often used agents in the ITU. Rocuronium has not yet been extensively assessed. Myorelaxants carry risks for morbidity and mortality. The difficulty to assess the neurological status and the level of sedation is a recognised adverse effect. An accidental disconnection from the circuit and the resulting asphyxia is nowadays recognised without delay by the ventilator. NBAs increase the rate of bronchopulmonary infections. Cardiovascular complications include extreme bradycardia or sinus arrest following vecuronium administration, and cardiac arrest after suxamethonium injection mainly in burned or traumatised patients. Conversely to anaesthesia, NBAs do not carry a significant risk for anaphylactic or anaphylactoid complications in the ITU. Tachyphylaxis occurs mainly in burns and other pathologies modifying acetylcholine receptors. Neuromuscular complications include myopathy from steroids, postparalytic syndrome, deconditioning syndrome and intensive care polyneuropathy. Prolonged curarisation after discontinuation of NBA administration has a multifactorial origin and must be differentiated from neuromuscular complications. For prolonged neuromuscular blockade, pancuronium, vecuronium and atracurium are the agents of choice. The association with an adequate sedation is essential. Assessment of depth of neuromuscular blockade is not based on clinical symptoms but on train-of-four (TOF) twitch monitoring. A convenient basic relaxation is usually obtained with the suppression of the two last responses to TOF. CONCLUSION: The use of NBA in ITU patient should result from a rational decision making procedure, the blockade titrated with a TOF monitor and maintained as superficially and shortly as possible.

The effect of hemodilution on cerebral blood flow velocity in anesthetized patients.

UNLABELLED: Transcranial Doppler is used to estimate changes in cerebral blood flow, but the effect of hemodilution on cerebral blood flow velocity (CBFV) in anesthetized patients has not been evaluated. The aim of this study was to measure the effect of isovolemic hemodilution on CBFV and lumbar cerebrospinal fluid pressure (P(CSF)) in anesthetized patients without change in other physiological variables that may affect CBFV. Patients undergoing hemodilution were compared with a control group undergoing no hemodilution. With hemodilution, hematocrit decreased from 38% +/- 3% to 30% +/- 2%, arterial oxygen content (Cao2) decreased from 17.5 +/- 1.3 to 13.9 +/- 0.9 mL/dL, and CBFV increased from 50 +/- 10 to 58 +/- 10 cm/s. An equivalent of cerebral arterial O2 transport calculated as Cao2 x CBFV did not significantly change. Over the same time interval, there were no changes in the control group. There was no statistically significant change in P(CSF), pulsatility index, Paco2, blood pressure, heart rate, or body temperature in either group. We conclude that CBFV reflects cerebral blood flow changes after hemodilution. IMPLICATIONS: Hemodilution increases cerebral blood flow but may change the cerebral artery diameter, which could confound perioperative measurement of cerebral blood flow velocity. This study found transcranial Doppler ultrasonography to accurately assess the effects of hemodilution on the cerebral circulation, but the hematocrit should be taken into account to fully understand perioperative cerebral blood flow velocity changes.

Influence of body temperature, with or without sedation, on energy expenditure in severe head-injured patients.

OBJECTIVE: To quantify the effect of body temperature and sepsis on energy expenditure in head-injured patients. DESIGN: Prospective, nonrandomized, observational study. SETTING: Neurosurgical intensive care unit. PATIENTS: Severe head-injured patients. INTERVENTIONS: Use of an indirect calorimeter to measure energy expenditure. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure (MAP), heart rate (HR), body temperature, and mean hourly energy expenditure were recorded. Twenty-four patients had 1,919 hourly measures of the above parameters. The measurement periods were divided into four groups, according to the anesthetic agents used for sedation: fentanyl and midazolam (group FM); fentanyl, midazolam, and curarization (group C); thiopental (group T); and no sedation (group NS). The energy expenditure/basal energy expenditure ratio (EE/BEE) was significantly lower in group T (1.20 +/- 0.15) than in group FM (1.32 +/- 0.24) or group C (1.32 +/- 0.20) and was significantly higher in group NS (1.60 +/- 0.33). There was a significant correlation between body temperature and EE/BEE (p < .0001, r2 = .27) only in sedated patients. Using the equation of the regression line to correct energy expenditure for differences in body temperatures between groups, the difference in energy expenditure between groups with sedation disappeared. This finding suggested that the low energy expenditure under thiopental was due only to hypothermia. Sepsis significantly increased energy expenditure independently of fever. There was a weak but statistically significant correlation between energy expenditure and HR (p<.01, r2 = .13) but not between energy expenditure and MAP. CONCLUSIONS: Sedation had a major effect on energy expenditure. In sedated patients, body temperature was the main determinant of energy expenditure; the anesthetic agent used had little influence on the level of energy expenditure. Sepsis increased energy expenditure independently of fever, probably through hormonal changes.