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Biomedical subjects

G Audibert

Publications and source records attributed to G Audibert.

At least 55 records · Page 3Linked to original sources
PubMed1996

The onset of rocuronium, but not of vecuronium or mivacurium, is modified by tourniquet inflation.

A previous investigation showed that inflation of a tourniquet did not interrupt onset of vecuronium neuromuscular block. To test the hypothesis that this effect depended on potency, twitch tension was measured in an arm with a tourniquet inflated during onset and compared with a control arm in 30 patients under fentanyl-thiopental-nitrous oxide-isoflurane anesthesia. Patients were randomly allocated to receive either vecuronium 0.1 mg/kg (n = 10), rocuronium 0.6 mg/kg (n = 10), or mivacurium 0.2 mg/kg (n = 10). The electromyographic response of the first dorsal interosseus to single twitch stimulation of the ulnar nerve every 10 s was recorded in both arms. When neuromuscular block was 20% (i.e., twitch tension was 80% of control), the tourniquet was inflated to a pressure of 300 mm Hg. It was deflated 5 min later. In the vecuronium and mivacurium groups, the tourniquet did not influence onset of block. In the rocuronium group, maximum neuromuscular block was (mean +/- SD) 79% +/- 10% in the tourniquet arm, compared with 96% +/- 4% in the perfused arm (P < 0.05). The maximum rate of onset was half that of the perfused arm. The difference in maximum neuromuscular block between arms was 17% +/- 7%, 5% +/- 5%, and 0% +/- 2% in the rocuronium, vecuronium, and mivacurium groups (P < 0.05). To explain that onset of block continues in spite of interruption of blood flow, drug molecules must gain access to the neuromuscular junction via routes other than the circulation. The results of this investigation are consistent with the hypothesis that there is redistribution of drug from extrajunctional to junctional areas during onset of action of muscle relaxants and this process is more important for the more potent drugs (vecuronium and mivacurium) than for rocuronium.

Adult↗
PubMed1995

[Outcome of the use of albumin and colloid plasma substitutes from 1989 to 1993 in a French University Hospital Center].

OBJECTIVES: To evaluate the use of plasma substitutes (albumin, gelatins, dextrans, starches) from 1989 to 1993 in a 3000-bed University hospital and to assess the impact of the 1989 consensus conference of the French speaking Society of Intensive Care Medicine on the choice of plasma substitutes for treatment of hypovolaemia. STUDY DESIGN: Retrospective study of a case series. METHODS: Data on the use of albumin and artificial plasma substitutes were obtained from Blood Bank and Pharmacy. RESULTS: Between 1989 and 1993, the total amount of administered plasma substitutes decreased by 20%, allowing a saving of 1.7 million FF. There was a 60% decrease in the use of gelatins and dextrans. The starches, introduced in 1991, became in 1993 the most used plasma substitute, with 37% of the total. The use of albumin showed only a 32% decrease and was still in 1993 the main source of expenditure for plasma substitutes, with 3.8 million FF and 80% of the total cost. The number of plasmapheresis increased by 15%, whereas the use of albumin for plasmapheresis, almost constant in absolute value, increased from 31% in 1989 to 45% in 1993 of the total expenses. There were large differences between the services regarding the use of albumin. Intensive care and surgical units represented 70% of the total (plasmapheresis excluded). In this group, the overall fall of use was 22%, some units obtaining a 93% decrease whereas other did not change in spite of constant admission numbers. Medical units decreased their albumin use by 53%. CONCLUSION: The decrease in the albumin use between 1989 and 1993 was not significant. The impact of the consensus conference, if any, was weak. A careful evaluation of the prescriptions would be necessary to improve the compliance of clinical practice with recommendations by the consensus conference.

Albumins↗
PubMed1995

Onset of neuromuscular block after tourniquet inflation: comparison of suxamethonium with vecuronium.

To determine the influence of circulatory factors on onset of neuromuscular block, we have measured twitch height in an arm with a tourniquet inflated during onset and compared this with data from a control arm in 20 patients under fentanyl-thiopentone-nitrous oxide-isoflurane anaesthesia. Patients were allocated randomly to receive either vecuronium 0.1 mg kg-1 (n = 10) or suxamethonium 1 mg kg-1 (n = 10). The EMG response of the first dorsal interosseous to single twitch stimulation of the ulnar nerve every 10 s was recorded in both arms. When neuromuscular block was 20% (i.e. twitch height was 80% of control), the tourniquet was inflated to a pressure of 250 mm Hg. It was deflated 5 min later. In the vecuronium group, the rate of onset did not differ in both arms and mean maximum block was 95 (SD 4)% in the tourniquet arm, which was not different from 99 (2)% in the perfused arm. In the suxamethonium group, the presence of a tourniquet decreased the rate of onset by 66%. Maximum block was only 74 (20)% in the tourniquet arm compared with 97 (5)% in the perfused arm (P < 0.05). The difference in maximum neuromuscular block between arms was 4 (3)% in the vecuronium group and 22 (17)% in the suxamethonium group (P < 0.01). We conclude that during onset, neuromuscular block continued to increase in spite of interruption of blood flow, and this increase was greater with vecuronium than with suxamethonium.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Effect of the inhibitor of nitric oxide synthase, NG-nitro-L-arginine methyl ester, on cerebral and myocardial blood flows during hypoxia in the awake dog.

The increase in cerebral blood flow (CBF) elicited by moderate hypoxia in anesthetized animals is little attenuated by nitric oxide (NO) synthase inhibitors. However, in previous studies, the effects of NO synthase inhibitors may have been altered by anesthetics. Consequently, we studied the effects of the NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on cerebral and myocardial blood flows during hypoxia in the awake dog. Regional CBF and myocardial blood flows (MBF) were measured under normoxia and hypoxia in 16 beagle dogs after an intravenous (IV) injection of either saline (control, n = 8) or L-NAME 20 mg/kg (n = 8). One week after thoracotomy for catheter insertion, awake dogs were studied during three periods: normoxia and after 2 and 4 h of normocapanic hypoxia in an environmental chamber (FIO2 = 0.10, FICO2 = 0.035, balance N2). At each stage, a bolus injection of L-NAME or saline was followed 15 min later by left atrial injection of radiolabeled microspheres (141Ce, 103Ru, 46Sc) for regional CBF and MBF. After the dogs were killed, the brain and the heart were fixed in 10% formaldehyde, dissected by region and weighed, and radioactivity was measured in a gamma counter. During hypoxia, Pao2 was approximately 45 mm Hg with normal Paco2. In the control group, CBF increased by 45% after 2 h and 48% after 4 h of hypoxia; MBF increased by 69% and 60%, respectively. L-NAME prevented the CBF increase during hypoxia and the MBF increase after 2 h of hypoxia; after 4 h of hypoxia the measurement of MBF was confounded by cardiac dysfunction. These results suggest that NO plays a role in cerebral vasodilation during hypoxia in the awake animal.

Animals↗
PubMed1995

Therapeutic optimization including inhaled nitric oxide in adult respiratory distress syndrome in a polyvalent intensive care unit.

OBJECTIVE: To investigate the effects of inhaled nitric oxide (NO) in adult respiratory distress syndrome (ARDS) associated with a therapeutic optimization strategy on oxygen parameters, barotrauma, and evolution in a medical and surgical intensive care unit. DESIGN: Prospective study. MATERIALS AND METHODS: Twenty consecutive patients with ARDS were studied (Murray score 3.6 +/- 0.2). Eleven were surgical patients and nine were medical patients. All fulfilled the extracorporeal membrane oxygenation entry criteria. The APACHE II score predicted mortality was 39%. All were ventilated with FiO2 1 with positive end-expiratory pressure (PEEP) of 11 +/- 1 cm H2O. Therapeutic optimization included permissive hypercapnia, tracheal gas insufflation, prone position, continuous hemofiltration, treatment of infection, and pleural drainage. We used NO continuously inhaled at a concentration ranging from 5 to 10 ppm. MEASUREMENTS AND MAIN RESULTS: After 1 hour, inhaled NO improved PaO2 in all patients except one (78 +/- 11 to 130 +/- 25 mm Hg) (p < 0.05), allowing a reduction of FiO2 and PEEP. After 24 hours, mean pulmonary arterial pressure decreased from 31 +/- 3 to 25 +/- 2 mm Hg (p < 0.05). Systemic hemodynamics were unaffected. Oxygen delivery increased from 531 +/- 135 to 603 +/- 125 mL/minute/m-2 (p < 0.05). Barotraumatic lesions were present in only one patient. Reversal of ARDS was obtained in 16 patients, of whom 14 (70%) were discharged. CONCLUSIONS: This study was shorter to demonstrate an improvement in the survival rate. Nevertheless, these preliminary results are encouraging. Because of its safety, effectiveness, and easy use, inhaled NO should be used as a part of a therapeutic optimization protocol before considering more invasive and expensive procedures, such as extracorporeal respiratory support or intravascular oxygenation.

APACHE↗
PubMed1994

[Spontaneous retroperitoneal hematoma: a rare cause of hemorrhagic shock].

A spontaneous retroperitoneal haematoma is an uncommon cause of haemorrhagic shock. We report a case of spontaneous rupture of a renal angiomyolipoma resulting in haemorrhagic shock in a 52-year-old woman. The renal tumor was recognized by sonography and diagnosed by CT-scan. Renal angiography was performed, but embolization was not successful. During the surgical procedure, nephrectomy was required because of persistent bleeding, related to disseminated intravascular coagulation. Outcome was uneventful. Diagnosis and treatment of renal angiomyolipoma are discussed. The Lenk's triad, consisting of acute lumbar pain, symptoms of internal bleeding and lumbar tumefaction, is the usual clinical picture of retroperitoneal haemorrhage. The kidney is the most frequent cause and renal angiomyolipoma is the most frequent benign tumor. Renal angiomyolipoma is either isolated or associated with tuberous sclerosis in up to 20 per cent of patients. Diagnosis is suggested by sonography and confirmed by CT-scan. Renal angiography, performed in haemodynamically stable patients, shows the origin of bleeding and allows embolization. Considering the frequent bilaterality of angiomyolipoma, surgery should be as conservative as possible in order to preserve renal function.

Blood Transfusion↗
PubMed1994

Rheologic effects of plasma substitutes used for preoperative hemodilution.

This study was designed to compare the influence of various plasma substitutes, administered for preoperative hemodilution, on blood rheology. We studied 40 patients, ASA grade I, who underwent elective facial reconstructive surgery and received 4% albumin (n = 10), 3.5% dextran 40 (n = 10), gelatin (n = 10), or hydroxyethyl starch (HES) (n = 10). Ten patients, undergoing the same surgical procedure without hemodilution, were chosen as controls. After hemodilution, hematocrit was decreased approximately 30%. Fibrinogen decreased in all tested groups except in the gelatin group. Plasma viscosity decreased with albumin (1.13 +/- 0.05 to 1.06 +/- 0.03 mPa.s; P < 0.01) and increased with HES (1.15 +/- 0.04 to 1.22 +/- 0.05 mPa.s; P < 0.01). At a high shear rate, the blood viscosity decreased in all groups. In contrast, at a low shear rate and at 40% corrected hematocrit, the blood viscosity decreased in the albumin (15.9 +/- 1.9 to 13.1 +/- 2.1 mPa.s; P < 0.01) and the dextran 40 (16.9 +/- 2.9 to 12.8 +/- 2.5 mPa.s; P < 0.01) groups and was unchanged in the gelatin and the HES groups. Erythrocyte aggregation (measured with primary aggregation time) was markedly decreased in the albumin (3.27 +/- 1.74 to 7.03 +/- 2.95 s; P < 0.01) and in the dextran 40 (2.72 +/- 0.58 to 6.24 +/- 2.55 s; P < 0.001) groups, unchanged with HES, and increased with gelatin (2.41 +/- 0.90 to 1.55 +/- 0.33 s). These findings suggest that albumin and dextran 40 may be the plasma substitutes of choice for preoperative hemodilution when this technique aims to improve rheologic conditions.

Adolescent↗
PubMed1994

[Indications of blood components and outcome of transfusion practices in hemorrhage of multiple trauma].

Bleeding occurring in a patient with multiple trauma has an unpredictable evolution; blood losses are often very important and their origins mostly unclear. These problems should not prevent the use of a strategy for optimal use of blood components. Indications for packed red cells, fresh frozen plasma, platelets and coagulation factors are discussed. Indications for packed red cells are discussed in relation with the patient's conditions (myocardial, cerebral and pulmonary functions) and the clinical status. If the patient is shocked, transfusion must be ordered to maintain a haemoglobin level greater than 10 g.100 ml-1. Considering its cost, the use of albumin must and can be reduced when fluid replacement is realized with long lasting colloids, like starch. Warming of transfused blood is necessary, especially if acceleration disposals are used to prevent or minimize hypothermia. Use of portable monitors for haemoglobin and coagulation parameters is recommended.

Blood Transfusion↗
PubMed1993

Effect of propofol and thiopentone on regional blood flow in brain and peripheral tissues during normoxia and hypoxia in the dog.

The effect of propofol and thiopentone on cerebral (CBF), myocardial (MBF), muscular, and arterial hepatic blood flow was assessed with radiolabelled microspheres in 12 chronically instrumented dogs, six given propofol and six thiopentone. Tissue blood flows were measured in the awake animal, after 30 min of normoxic anaesthesia (room air), and after 30 min of hypoxic anaesthesia using a mixture of 10% O2 and 3% CO2 in nitrogen. The decrease in CBF from awake to normoxic anaesthesia was similar with propofol and thiopentone (propofol: 77 +/- 8 to 38 +/- 3 ml min-1 100 g-1, P < 0.01; thiopentone: 66 +/- 3 to 33 +/- 2 ml min-1 100 g-1, P < 0.01). During hypoxia, CBF rose moderately in the two groups (respectively +19% and +28%, P < 0.05). The MBF increased in propofol and thiopentone groups after 30 min of anaesthesia with air (propofol: 97 +/- 23 to 137 +/- 15 ml min-1 100 g-1; thiopentone: 82 +/- 7 to 141 +/- 10 ml min-1 100 g-1) and increased still more during hypoxia. The increase in MBF was related to an increase in heart rate and blood pressure. The quadriceps blood flow decreased during anaesthesia in normoxia and in hypoxia. The diaphragmatic blood flow increased with thiopentone under hypoxia. The hepatic arterial blood flow was unchanged. It is concluded that the effects of propofol on regional blood flows are very similar to those of thiopentone.

Anaerobiosis↗
PubMed1993

[Factors prognostic of acute kidney insufficiencies following vascular surgery].

Acute renal failure (ARF) following vascular surgery is still associated with high mortality and morbidity rates. A retrospective study of 33 patients, admitted in ICU for ARF following the surgical treatment of aortic occlusive or aneurysmal diseases, was undertaken to determine the risk factors, clinical settings and prognosis of postoperative renal failure. There were 29 men and 4 women, with a mean age of 63 years and SAPS of 18. The surgical procedure was scheduled in more than 50% of the cases. The mortality rate was extremely high (79%); only 4 out of 33 patients were discharged without sequelae. History and clinical settings had addictive effects for the development of postoperative renal failure. Most patients who had sustained oliguria or who developed septic shock or multiple organ failure were associated with poor prognosis. The conclusion is that the prognosis of acute renal failure after vascular surgery depends more on the occurrence of multiple organ failure than the acute renal failure by itself.

Acute Kidney Injury↗
PubMed1992

Nalbuphine analgesia preserves ventilation after thoracotomy despite a reduction in inspiratory drive.

The respiratory effects of analgesia with nalbuphine were studied in 9 patients after thoracotomy. The pain score was measured by a visual analogue scale. Ventilatory pattern and occlusion pressure (P0.1) were studied during spontaneous breathing and during CO2 rebreathing, before and 0.5, 1, 2.5, 3.5 and 6 h after a 0.3-mg.kg-1 dose of intravenous nalbuphine. Compared to baseline values obtained before the injection, nalbuphine produced a decrease in the pain score (p < 0.001) during the 6-hour experiment period. In spontaneous breathing, P.01 was reduced by 15% in 1 h and remained decreased during 3.5 h (p < 0.05), whilst PaCO2 and ventilation (VE) remained unchanged. The P0.1 responsiveness to CO2 was decreased from 0.5 to 2.5 h after the nalbuphine injection (p < 0.05), but the VE responsiveness to CO2 was reduced only after 1 h (p < 0.01). This study shows that, while post-thoracotomy pain was reduced by analgesia, neuromuscular inspiratory drive and chemosensitivity to CO2 were weakened, without any change in spontaneous ventilation. A partial improvement in the thoracopulmonary mechanics induced by the reduction in chest pain could explain the maintenance of ventilatory level in spite of a decreased neuromuscular inspiratory drive.

Analysis of Variance↗
PubMed1991

Preserved CO2 response in cerebral and muscular blood vessels during cimetidine treatment.

It is known that cimetidine inhibits the hypoxia-induced increase in cerebral blood flow (CFB) in dogs, but the mechanism of this inhibition is not fully understood. Since the accepted mechanisms explaining the increase in CBF during hypercapnia are very different from those active during hypoxia, acute hypercapnia was induced in 12 conscious dogs in order to study the cimetidine effect in this condition. Six dogs were given i.v. saline (control group) and the other six, i.v. cimetidine (4 mg kg-1). After 15 min, CBF and various muscular blood flow measurements were performed, using the microspheres technique under two conditions: (1) breathing air and (2) after 2 h inhalation of a gas mixture with FiCO2 0.10, FiO2 0.21 in nitrogen. The CBF increase was similar in both series with or without cimetidine. The changes in muscular blood flow were unaffected by the H2-blocker. We conclude that cimetidine has no effect on the CBF and on muscular blood flow during acute hypercapnia.

Animals↗
PubMed1991

Effects of H2-receptor blockers on response of cerebral blood flow to normocapnic hypoxia.

Cimetidine blunts the increase in cerebral blood flow (CBF) normally observed during hypoxia. It is important, therefore, to know whether other H2-blockers also affect the cerebral circulation adaptation to hypoxia. Cerebral blood flow was measured in 24 awake dogs after an intravenous injection of either saline (control) or one of three H2-blockers: 1 mg/kg ranitidine, 0.4 mg/kg famotidine, or 1 mg/kg roxatidine. These doses are equipotent blockers of H2-gastric receptors. Each dog was studied during normoxia and after 2 and 4 h of normocapnic hypoxia (FIO2, 0.10; FICO2, 0.035). During each set of experimental conditions, a bolus of either saline or one of the anti-H2 drugs was administered, and, 15 min later, radiolabeled microspheres (ruthenium 103, scandium 46, and cerium 141) were injected into the left atrium for measurement of regional CBF. After death by an overdose of thiopental, each dog's brain was excised and fixed in 10% formaldehyde; it was then weighed and dissected by region, with the radioactivity measured in each region using a gamma counter. During hypoxia, PaO2 ranged from 45 to 50 mm Hg, and pH, PaCO2, and hematocrit were within the normal limits. In the control group CBF increased 34% above normoxic baseline levels after 2 h and 31% after 4 h of hypoxia. Ranitidine (1 mg/kg) did not prevent the increase in CBF during hypoxia, but famotidine and roxatidine prevented it. When the dose of ranitidine was doubled (2 mg/kg), it too abolished the increase of CBF induced by hypoxia. In conclusion, H2-receptor blockers could interfere with the adaptation of CBF during hypoxia.

Animals↗
PubMed1990

Effects of epinephrine on hemodynamics and oxygen metabolism in dopamine-resistant septic shock.

The hemodynamic effects of epinephrine were prospectively studied in 13 patients with septic shock who remained hypotensive after both fluid loading and dopamine. Hemodynamic measurements were performed before and one hour after the start of epinephrine infusion. Systolic, diastolic, and mean arterial pressure increased in all patients (p less than 0.01). Cardiac index and systemic vascular resistance increased by 34 and 32 percent, respectively (p less than 0.05), but heart rate and pulmonary vascular resistance remained unchanged. There was a concomitant increase in oxygen delivery (p less than 0.01) and oxygen consumption (p less than 0.05), the magnitude of the latter being related to baseline lactacidemia (p less than 0.01). In view of the generally recognized physiologic goals of septic shock management, we conclude that epinephrine could be an appropriate alternative where fluid loading and dopamine have failed.

Adolescent↗
PubMed1990

[Polytraumatized patient. First aid care, transport and resuscitation].

The initial management of multiple trauma must achieve a triple aim: performing the actions required by a vital emergency, preventing as well as possible the complications associated with the initial lesions, and, most importantly, bringing the injured person into hospital in the best possible conditions for emergency surgery. Achieving these aims requires a perfect coordination of medical and nonmedical rescue. A rough initial categorization is important to decide whether additional medical staff is desirable, choose the type of transport planned (by ambulance, helicopter...) as well as the department or hospital due to receive the patient. Four actions must be accomplished, most often jointly, all of them contributing to the quality of treatment: 1. picking up/freeing/immobilizing the injured person, 2. controlling the hypovolemic collapse and the traumatic shock, 3. dealing with the associated distresses, 4. suppressing pain. The techniques used to pick up, free and immobilize the injured person require a close co-operation with the rescuing staff (stretcher bearers, fire department, first-aid workers). The hypovolemic shock is treated by volume replacement, mainly with colloids. Local hemostasis may sometimes be necessary. Anti-shock trousers should be widely used in cases of multiple trauma. Dealing with the associated distresses gives priority to ventilation. The indications of ventilatory support must be very wide whenever coma or signs of respiratory distress are noted, more so with an associated shock. The indications of aspiration of a gaseous or fluid pleural effusion must also be discussed. Maximal suppression of pain must be kept in mind throughout all these operations.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia↗