PubMed Health⌕ Search

Biomedical subjects

B Tavernier

Publications and source records attributed to B Tavernier.

At least 37 records · Page 2Linked to original sources
PubMed1999

Recovery after anaesthesia for pulmonary surgery: desflurane, sevoflurane and isoflurane.

We have studied maintenance and recovery profiles after general anaesthesia with sevoflurane, desflurane and isoflurane in 100 patients undergoing pulmonary surgery. End-tidal concentrations of anaesthetic required to maintain mean arterial pressure and heart rate within 20% of baseline values were 1.4 +/- 0.6% for sevoflurane, 3.4 +/- 0.9% for desflurane and 0.7 +/- 0.3% for isoflurane. The three anaesthetics had comparable haemodynamic effects and arterial oxygenation during one-lung ventilation. Emergence was twice as fast with desflurane than with sevoflurane or isoflurane (mean times to extubation: 8.9 (SD 5.0) min, 18.0 (17.0) min and 16.2 (11.0) min for desflurane, sevoflurane and isoflurane, respectively). Early recovery (Aldrete score, cognitive and psychomotor functions) was also more rapid after desflurane. In pulmonary surgery, desflurane, but not sevoflurane, allowed more rapid emergence and earlier recovery than isoflurane.

Adult↗
PubMed1999

Halothane induces calcium release from human skinned masseter muscle fibers.

BACKGROUND: An increase in masseter muscle tone in response to halothane or succinylcholine anesthesia (or both) can be observed in healthy persons. Thus the authors compared the fiber-type halothane and succinylcholine sensitivities in human masseter and vastus lateralis muscles. METHODS: Masseter and vastus lateralis muscle segments were obtained from 13 and 9 healthy persons, respectively. After chemical skinning of a single fiber and loading the sarcoplasmic reticulum with Ca++ 0.16 microM solution, halothane (0.5-4 vol% bubbled in the incubating solution), succinylcholine (0.1 microM to 10 mM), or both sensitivities were defined as the concentration inducing more than 10% of the maximum tension obtained by application of 16 microM Ca++ solution. The myofilament response to Ca++ was studied with and without halothane by observing the isometric tension of skinned masseter fibers challenged with increasing concentrations of Ca++. Muscle fiber type was determined by the difference in strontium-induced tension measurements. RESULTS: A significant difference in halothane sensitivity was found between type 1 masseter fibers (0.6+/-0.2 vol%; mean +/- SD) versus type 1 (2.7+/-0.6 vol%) and type 2 vastus lateralis muscle (2.5+/-0.4 vol%). Succinylcholine did not induce Ca++ release by the sarcoplasmic reticulum. In the masseter muscle, 0.75 vol% halothane decreased the maximal activated tension by 40% but did not change the Ca++ concentration that yields 50% of the maximal tension. CONCLUSIONS: The very low halothane threshold for Ca++ release from the masseter muscle usually could be counteracted by a direct negative inotropic effect on contractile proteins. However, halothane may increase the sensitivity of the sarcoplasmic reticulum Ca++ release to succinylcholine-induced depolarization, leading to an increase in masseter muscle tone.

Adult↗
PubMed1999

Sequential changes in autonomic regulation of cardiac myocytes after in vivo endotoxin injection in rat.

We report that in vivo injection of endotoxin (EDTX, 6 mg. kg(-)(1)) induces cardiovascular alterations in rats that closely mimic the clinical situation, as assessed by in vivo hemodynamic measurements in anesthetized and conscious, chronically instrumented animals. The patch-clamp technique was used to characterize the L-type calcium current (I(Ca)) and its autonomic regulation in isolated cardiac myocytes. The density of I(Ca) progressively decreased at 12 and 36 h after EDTX injection. However, the dihydropyridine (+/-)Bay K 8644 (100 nM) enhanced I(Ca) to levels similar to those in control and EDTX-treated myocytes. In addition, the net stimulatory effect of a beta-adrenergic agonist (isoproterenol) on I(Ca) was increased 12 h after EDTX injection. This change in the beta-adrenergic effect declined 24 h later. The potentiation in the beta-adrenergic stimulation of I(Ca) was mimicked by L858051 (10 microM), a direct activator of adenylyl cyclase, but not by IBMX (200 microM), a phosphodiesterase inhibitor. Besides, the antiadrenergic effect of acetylcholine on I(Ca) was unchanged 12 h after EDTX injection, but increased 36 h after EDTX injection. These results support the hypothesis that time-dependent changes in the adenylyl cyclase pathway in cardiac myocytes may contribute, via the autonomic regulation of I(Ca), to the severity of myocardial dysfunction during sepsis.

1-Methyl-3-isobutylxanthine↗
PubMed1999

In vitro study of the retention and mechanical fatigue behavior of four implant overdenture stud-type attachments.

This study sought to determine the influence of mechanical fatigue on four varieties of implant overdenture studtype attachments (Supra-Snap, O'Ring, TSIB, ZAAG). Measurements of the initial vertical retentive force and the weight of the implant abutment were recorded. The same procedure was performed after the equivalent of 2 months, 6 months, and 12 months of clinical wear. For the four attachments, weight variation of the abutment between 0 and 1,080 cycles demonstrated no significant difference. Results indicated the TSIB to be significantly most retentive; next most retentive was the O'Ring, followed respectively by Supra-Snap and ZAAG.

Dental Prosthesis Design↗
PubMed1998

Myofilament calcium sensitivity is decreased in skinned cardiac fibres of endotoxin-treated rabbits.

OBJECTIVE: The aim was to determine whether myofilament Ca2+ sensitivity is altered in skinned cardiac fibres from endotoxin-treated rabbits. METHODS: Endotoxin was injected i.v. in conscious New-Zealand White rabbits at a dose of 0.5 mg/kg (groups I, II, and III) or 1 mg/kg (group IV). A fifth group was used as control. Hearts were excised 4 h (groups I and IV), 24 h (group II), or 5 days (Group III) after injection. Skinned fibres were obtained with chemical (EGTA + Brij 58) treatment of bundles isolated from papillary muscles. RESULTS: The maximal Ca(2+)-activated force (F0) of skinned cardiac fibres was not different between groups. However, [Ca2+] required to evoke 50% of F0 (Ca50) was higher in the fibres from group I than in controls (1.78 +/- 0.05 vs. 1.53 +/- 0.03 microM; P < 0.05). This effect was dose-dependent (group IV: Ca50 = 2.08 +/- 0.12 microM; P < 0.05 vs. group I), larger after 24 h (group II: Ca50 = 2.12 +/- 0.05 microM; P < 0.05 vs. group I). By 5 days, myofilament Ca2+ sensitivity had returned to normal (group III: Ca50 = 1.54 +/- 0.05 microM). CONCLUSION: Myofilament Ca2+ sensitivity is decreased in skinned fibres taken from rabbit myocardium after i.v. endotoxin injection. This effect is dose- and time-dependent, and reversible with time.

Actin Cytoskeleton↗
PubMed1998

Paracrine regulation of cardiac myocytes in normal and septic heart.

A paracrine pathway for the regulation of cardiac contractile function by nonmuscle cells is documented in the heart. Coronary and endocardial endothelium release several diffusible agents, such as prostaglandins, endothelin-1, and nitric oxide, with an action on cardiac myocyte function. Cardiac diseases involving an immune or inflammatory mechanism, such as endotoxic shock, are now seen as conditions in which cross-talk between different cell types in the heart is clearly implicated. The potential biological relevance of inducible nitric oxide synthase in the myocardium, and the subsequent production of nitric oxide has been proposed as a mechanism of the cardiac depression observed in septic shock. In addition to cardiac myocytes, activated microvascular endothelial cells and cardiac endothelial cells may contribute to nitric oxide generation and, ultimately, to the depression of myocardial contractile activity during sepsis. This article reviews the local intercellular communication between cardiac myocytes and endothelial cells in the normal heart and discusses some of the mechanisms potentially claimed to depress heart function in sepsis.

Endothelium↗
PubMed1998

Effects of halothane on mechanical response of skeletal muscle from malignant hyperthermia susceptible patients.

The purpose of this investigation was to compare the effects of halothane on malignant hyperthermia (MH) and normal isolated muscle bundle performance during isometric contraction and relaxation phases. Mechanical parameters were measured: peak tension (PT), time to peak tension (TPT) and positive peak of isometric tension derivative (+dP/dtmax) characterized the contraction phase. Half-relaxation time (RT1/2) and negative peak of isometric tension derivative (-dP/dtmax) characterized the relaxation phase. The ratio R = (+dP/dtmax)/(-dP/dtmax) was used to study the coupling between contraction and relaxation under isometric condition. In normal muscle, halothane increased PT by nearly 40% without altering TPT. The +dP/dtmax value increased concomitantly with the -dP/dtmax values, thus no changes in R was observed. In MH muscle, PT was first potentiated (0.5-1.0 vol% halothane) and then depressed (2.0-3.0 vol% halothane). TPT and +dP/dtmax were not altered whereas RT1/2 increased progressively with concomitant decrease in -dP/dtmax, thus R increased by nearly 40%. The amplitude of MH muscle contracture with stepwise concentrations of halothane was correlated with the increase of RT1/2 and R, and the decrease of -dP/dtmax. These results suggest that halothane alters the relaxation phase more than the contraction phase in MH human skeletal muscle compared to normal muscle.

Anesthetics, Inhalation↗
PubMed1998

Systolic pressure variation as a guide to fluid therapy in patients with sepsis-induced hypotension.

BACKGROUND: Monitoring left ventricular preload is critical to achieve adequate fluid resuscitation in patients with hypotension and sepsis. This prospective study tested the correlation of the pulmonary artery occlusion pressure, the left ventricular end-diastolic area index measured by transesophageal echocardiography, the arterial systolic pressure variation (the difference between maximal and minimal systolic blood pressure values during one mechanical breath), and its delta down (dDown) component (= apneic - minimum systolic blood pressure) with the response of cardiac output to volume expansion during sepsis. METHODS: Preload parameters were measured at baseline and during graded volume expansion (increments of 500 ml) in 15 patients with sepsis-induced hypotension who required mechanical ventilation. Each volume-loading step (VLS) was classified as a responder (increase in stroke volume index > or = 15%) or a nonresponder. Successive VLSs were performed until a nonresponder VLS was obtained. RESULTS: Thirty-five VLSs (21 responders) were performed. Fluid loading caused an overall significant increase in pulmonary artery occlusion pressure and end-diastolic area index, and a significant decrease in systolic pressure variation and delta down (P < 0.01). There was a significant difference between responder and nonresponder VLSs in end-diastolic area index, systolic pressure variation, and dDown, but not in pulmonary artery occlusion pressure. Receiver-operator curve analysis showed that dDown was a more accurate indicator of the response of stroke volume index to volume loading than end-diastolic area index and pulmonary artery occlusion pressure. A dDown component of more than 5 mmHg indicated that the stroke volume index would increase in response to a subsequent fluid challenge (positive and negative predictive values: 95% and 93%, respectively). CONCLUSION: The dDown component of the systolic pressure variation is a sensitive indicator of the response of cardiac output to volume infusion in patient with sepsis-induced hypotension who require mechanical ventilation.

Aged↗
PubMed1998

[Exclusive use of calcium channel blockers and cardioselective beta-blockers in the pre- and per-operative management of pheochromocytomas. 70 cases].

The pre and intraoperative use of calcium channel blockers (CCB) has been suggested for the management of either eutopic or ectopic pheochromocytomas. We report our experience of 70 pheochromocytomas, operated between 1988 and 1996 and managed with CCB, especially nicardipine. 59 were hypertensive (84.2%). Preparation consisted of nicardipine in 61 patients or another CCB in 9 cases with duration ranging from 24 hours to several weeks depending on plasma volume and blood pressure control. Intraoperatively, nicardipine infusion was started after intubation, adjusted according to systolic blood pressure (SBP) and stopped before ligation of the tumor venous drainage. Increases in SBP greater than 200 mmHg were observed in 10 patients and were effectively controlled by nicardipine in all cases. In 16 patients, the S > BP remained less than 150 mmHg throughout anesthesia. Heart rate greater than 100 b p m occureed in 51 patients and was easily controlled with esmolol whenever used (n = 27). Arythmias were unfrequent (n = 4) and required treatment in only one case. This study confirms the ability to adequately manage pheochromocytomas with the use of nicardipine as sole vasodilating agent.

Adolescent↗
PubMed1997

Can prolonged expiration manoeuvres improve the prediction of arterial PCO2 from end-tidal PCO2?

We have studied, in 16 patients undergoing thoracoabdominal oesophagectomy, if two prolonged expiration manoeuvres improve prediction of arterial PCO2 (PaCO2) from end-tidal PCO2 (PE' CO2). PE' CO2, PCO2 at the end of a simple prolonged expiration (PE1 CO2), and PCO2 at the end of a prolonged expiration preceded by sustained hyperinflation of the lungs (PE2 CO2), were measured during laparotomy, in the lateral thoracotomy position during two-lung ventilation, and after transition to one-lung ventilation. (PaCO2-PE' CO2) was 1.3 (SD 0.4) kPa during laparotomy and this remained stable throughout the study. Both manoeuvres decreased the mean arterial to peak expired PCO2 difference, particularly during one-lung ventilation. However, PE1 CO2 and PE2 CO2 did not agree more closely with PaCO2 than PE' CO2 at any stage of the study. We conclude that these manoeuvres did not improve estimation of PaCO2 from PE' CO2.

Aged↗
PubMed1997

[Anesthesia-resuscitation in surgery for pheochromocytoma].

The perioperative mortality related to cardiovascular complications has been almost completely eliminated in phaeochromocytoma surgery. The anaesthetic management has mainly evolved through refinements in haemodynamic control during the operation. Neither preoperative preparation nor general anaesthesia can totally prevent haemodynamic disturbances during surgical manipulation of the tumour or after removal of the tumour. General anaesthesia, with high doses of opioids, remains the most usual technique. Intraoperative monitoring should include an arterial catheter and a pulmonary arterial catheter. Although a number of antihypertensive drugs have been tested, the preventive use of nicardipine i.v. may provide a simple and effective haemodynamic control. Esmolol, an ultrashort acting agent, ensures a dose-related cardiac beta 1-blockade. It is used for the treatment of arrhythmia and cardiac adrenergic stimulation, which causes tachycardia and increases cardiac output. Volume loading is recognised as the treatment of choice for hypotension following tumour removal. During the postoperative period, the great hazard is hypoglycaemia, and plasma glucose levels should be monitored over the immediate postoperative hours.

Adrenal Gland Neoplasms↗
PubMed1996

Liver transplantation without the use of fresh frozen plasma.

In orthotopic liver transplantations (OLT), fresh frozen plasma (FFP) is classically used to normalize coagulation factor concentrations. In this study, 28 OLT were performed without the use of FFP. According to their preoperative factor V (FV) levels, two groups of patients were defined: Group 1 (13 patients, FV > 10% and < 60%) and Group 2 (15 patients, FV > 60%). Spontaneous evolution of coagulation factors, concentration, and bleeding were observed during OLT and up to 48 h after surgery. Total intraoperative bleeding was similar in both groups (3460 +/- 2700 mL and 3470 +/- 2110 mL in Groups 1 and 2, respectively). Levels of clotting factors were not different between groups after the anhepatic stage. The lowest values were noted after reperfusion. Thirty-six hours after surgery, all levels of clotting factors in both groups were more than 50%, with FV level increasing the most rapidly. Hematocrit from the subhepatic drainage liquid was 1.8% and less than 1% at 24 and 48 h, respectively, after surgery. No reintervention for bleeding was necessary. These results suggest that, in OLT, correct hemostasis can be assumed without FFP use when hyperfibrinolysis, platelet count, fibrinogen rate, and hemodynamic status are controlled.

Adult↗
PubMed1994

[Lack of sensitivity to per-anesthetic malignant hyperthermia in 32 patients who developed neuroleptic malignant syndrome].

The aim of this study was to verify whether a relationship exists between neuroleptic malignant syndrome (NMS) and anaesthetic-induced malignant hyperthermia (MH) or not. The in vitro halothane-caffeine tests were performed on muscle tissue obtained from 32 patients with documented NMS episodes. The diagnosis of NMS relied on Levenson's criteria. The results, expressed in accordance with the criteria of the European MH Group, defined 29 subjects as MH non-susceptible. Three patients were classified as MH equivocal. These findings demonstrate the lack of any link between NMS and MH. Therefore, patients with a history of NMS are not likely to be at risk of developing MH and special measures against MH are not required for anaesthesia in these patients.

Adolescent↗