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Biomedical subjects

J L Teboul

Publications and source records attributed to J L Teboul.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effects of catecholamines on the pulmonary venous bed in sheep.

OBJECTIVE: To assess the effects of various catecholaminergic agents on pulmonary venous tone. DESIGN: Prospective, randomized, controlled, experimental study. SETTING: Physiology laboratory of a university hospital. SUBJECTS: Thirty anesthetized, mechanically ventilated adult sheep. INTERVENTIONS: Four groups of six animals received 1-hr infusions of norepinephrine (0.5 microg/kg/min), epinephrine (0.5 microg/kg/ min), dopamine (10 microg/kg/min), or dobutamine (10 microg/kg/min). MEASUREMENTS AND MAIN RESULTS: A 7-Fr pulmonary artery catheter was placed in a proximal location to measure cardiac output and pressure in a large pulmonary vein (Ppw) after balloon inflation. Another catheter wedged in a small pulmonary artery measured pressure in a small pulmonary vein (Pdw). A third catheter measured left atrial pressure (PLA ). This method was able to detect the pulmonary venoconstrictive effects of histamine in a separate group of six animals. Pdw-PLA increased from a mean of 2.0+/-1.7 to 3.0+/-1.5 (SD) cm H2O (p < .01), 2.3+/-1.6 to 4.4+/-1.3 cm H2O (p < .01), and 1.7+/-1.0 to 3.5+/-2.2 cm H2O (p < .05) with norepinephrine, epinephrine, and dopamine, respectively. All of these drugs increased Pdw-Ppw, but only norepinephrine and epinephrine increased Ppw-PLA . No change in either pressure difference was observed with dobutamine. Elevation of cardiac output alone could not account for these findings since the increase in cardiac output induced by fluid infusion did not change the pressure differences. CONCLUSION: Norepinephrine, epinephrine, and dopamine at doses commonly used in humans increase pulmonary venous tone in sheep.

Animals↗
PubMed1997

Inverse ratio ventilation (I/E = 2/1) in acute respiratory distress syndrome: a six-hour controlled study.

To assess the cardiorespiratory effects of a prolonged application of inverse ratio ventilation (IRV), we compared IRV (I/E = 2) with conventional ventilation (CV) (I/E = 0.5), applied for 6 h each in a randomized order, with constant tidal volume (VT) and total positive end-expiratory pressure (PEEP(tot)) in eight patients with acute respiratory distress syndrome (ARDS). After 1 h, IRV resulted in a lower peak inspiratory pressure (PIP) (28.2 +/- 1.5 versus 35.6 +/- 1.7 cm H2O, p < 0.05), an unchanged plateau pressure, and a higher mean airway pressure (MAP) (17.8 +/- 0.8 versus 15.6 +/- 0.5 cm H2O, p < 0.05) than CV. No significant difference in Pa(O2) and shunt fraction (QS/QT) was observed (83 +/- 7 mm Hg and 40 +/- 4% in CV versus 92 +/- 14 mm Hg and 35 +/- 3% in IRV, respectively). The Pa(CO2) was lower in IRV (48 +/- 3 versus 55 +/- 5 mm Hg, p < 0.05). Cardiac index (CI) and oxygen delivery (D(O2)) were lower in IRV (3.7 +/- 0.4 L/min/m2 and 500 +/- 61 ml/min/m2 versus 4.6 +/- 0.5 L/min/m2 and 617 +/- 80 ml/min/m2, respectively, p = 0.05 for both). Regardless of the considered parameter, no significant difference was observed between results after 1, 2, 4, and 6 h in each mode. We conclude that IRV at a ratio that results in a significant intrinsic PEEP does not improve Pa(O2), enhances CO2 elimination, decreases cardiac output (CO), and does not exert any time-dependent effect.

Adult↗
PubMed1997

Elastic energy as an index of right ventricular filling.

BACKGROUND: Right ventricle (RV) preload assessment remains controversial because the complexity of RV geometry is an obstacle to wall stress modeling. We developed a method to evaluate end-diastolic RV elastic energy (EL), a variable that integrates all the stretching effects of venous return and that can be easily estimated at the bedside from the area under the diastolic RV pressure-volume curve. The purpose of this study was to compare the clinical utility of EL and of the two conventional variables used to assess RV filling, ie, right atrial pressure (Pra) and RV end-diastolic volume (EDV). METHOD: We studied 26 postoperative patients who required a rapid fluid challenge. Energetics were evaluated by constructing the RV pressure-volume loop at the bedside using right heart catheterization with RV ejection fraction (EF) derivation. Correlations between RV filling and RV performance (ejection and mechanical efficiency) were studied. RV filling indexes were Pra, EDV, and EL. Indexes of RV ejection were stroke volume (SV), RV stroke work (RVSW), mechanical energy expenditure during ejection (EM), and total energy expenditure of contraction (ET). Indexes of RV mechanical efficiency were EF and the EM/ET ratio. RESULTS: Three important results were obtained. First, among RV ejection indexes, those that correlated best with RV filling indexes were EM and ET. Second, we found significant linear relationships between improved RV filling, as assessed by changes in EDV and EL, and improved RV ejection, as assessed by changes in SV, RVSW, EM, or ET. Third, changes in EDV and EL also predicted improved mechanical efficiency, as assessed by changes in EF and EM/ET. In, all situations, changes in EL yielded the strongest correlations. CONCLUSIONS: Derivation of EL is simple and appears to be the best clinical means of assessing Starling's law of the heart for the RV.

Adult↗
PubMed1996

[Hemodynamic management of septic shock. From a global approach to a gastrointestinal approach].

Oxygen uptake and increased metabolic requirements are characteristic of the acute state resulting from septic shock. One therapeutic approach to improving hemodynamics is to increase oxygen delivery in an attempt to overcome tissue oxygen debt. Recent randomized trials have suggested that systematically increasing oxygen supply is not necessarily the ideal strategy. It might be better, for each patient, to reach an optimal oxygen supply. This requires identification of parameters capable of indicating the optimal level, a rather difficult task. Currently, focus has been placed on the importance of the splanchnic circulation in severe septic shock. Hypoxia resulting from hypoperfusion of the intestinal mucosa occurs early in sepsis and could, via intermediary bacterial and/or endotoxinic translocation, maintain the septic syndrome and favor development of multiple organ failure. Since the drugs used to restore hemodynamics have vasoactive properties, measuring their effect on relevant indicators of splanchnic perfusion and oxygenation such as PCO2 or pH within the gastric mucosa using tonometric gastric probes might be a means of determining optimal oxygen level. With this approach, it would be possible to avoid sacrifying the perfusion of the gastrointestinal mucosa by using drugs which appear to favor the microcirculation in this territory.

Digestive System↗
PubMed1995

Global energetic failure in brain-dead patients.

The objective of this prospective, clinical study of consecutive patients was to test the hypothesis of a global energetic failure in brain-dead patients by analyzing indices of peripheral oxygenation during brain-dead resuscitation. Subjects comprised 24 subjects with brain death criteria from a multidisciplinary intensive care unit. The causes of brain death were multiple: severe traumatic head injury, cerebrovascular event, cerebral anoxia, primary brain tumor, and gunshot wound to the head. Interventions used were radial and pulmonary artery catheterization. Hemodynamic and gasometric parameters and blood lactate levels were measured immediately after the diagnosis of brain death (T0) and 4 hr later (T4), while patients were receiving a therapeutic protocol (fluids, vasopressive drugs) adjusted to reach a mean arterial pressure of 75 mmHg. In 18 of our 24 patients, a blood lactate level > or = 2 mmol/L (mean +/- SD: 4 +/- 2 mmol/L) associated with an increased mean lactate to pyruvate ratio (14.4 +/- 3.2) was observed at T0, while oxygen delivery (DO2) was high (533 +/- 208 ml/min/m2) and mean arterial pressure was 76 +/- 21 mmHg. Patients were subdivided into two groups according to changes in DO2 from T0 to T4: group D comprised 14 patients (10 with hyperlactatemia and 4 with normal lactate) in whom DO2 and oxygen consumption (VO2) simultaneously decreased from T0 to T4 without significant change in lactate level; group I comprised 10 patients (8 with hyperlactatemia and 2 with normal lactate) in whom DO2 and VO2 simultaneously increased, while the blood lactate level decreased significantly from 3.5 +/- 2.5 mmol/L at T0 to 2.1 +/- 1.0 mmol/L at T4 (P < 0.05). Our results indicate that the brain-dead state was frequently associated with a global energetic failure probably due to a cellular oxygen deficit, despite blood pressure within the normal range. This energetic failure, because it is associated with high levels of DO2, could result from a defect in peripheral oxygen extraction. Aggressive therapy, achieved by producing a further increase in DO2, may reduce this global tissue oxygen deficit.

Adolescent↗
PubMed1995

Spontaneous pneumothorax. Comparison of thoracic drainage vs immediate or delayed needle aspiration.

In the first part of this study, 61 patients admitted for the first episode or the first recurrence of a spontaneous pneumothorax (SP) were randomly treated with thoracic drainage (TD; 28 patients) or with simple needle aspiration (NA; 33 patients). Success rate of therapy was significantly higher with TD than with NA (93%, CI 84 to 100 vs 67%, CI 51 to 83; p = 0.01). Hospital stay was similar between the two groups (7 +/- 4.6 vs 7 +/- 5.6 days), mainly because NA was delayed by 72 h in 26 patients. Recurrence rates at 3 months were 29% (CI 11 to 47%) after TD, and 14% (CI 0 to 29%) after NA (p > 0.20, NS). In the second part of the study, an additional population of 35 patients was treated by immediate NA, with a success rate of 68.5% (CI 53.5 to 83.5%), and a recurrence rate at 3 months of 30% (CI 10 to 50%). Taken together, our results indicate that NA may be proposed as a first-line treatment of SP, with a successful result in two thirds of patients and recurrence in one fifth of patients. In patients who do not heal with NA, a combined risk of TD failure and short-term recurrence of 50% may be an incentive for undelayed surgical procedures.

Adolescent↗
PubMed1994

Left ventricular function during weaning of patients with chronic obstructive pulmonary disease.

OBJECTIVE: Determine the evolution of left ventricular ejection fraction during weaning. DESIGN: Prospective study. SETTING: Intensive care unit of a university teaching hospital. PATIENTS AND PARTICIPANTS: 12 consecutive mechanically ventilated patients, without documented coronary artery disease, suffering from acute exacerbation of chronic obstructive pulmonary disease and able to be weaned. MEASUREMENTS AND RESULTS: Left ventricular ejection fraction was determined during mechanical ventilation, inspiratory pressure support (10 cmH2O) and spontaneous ventilation with constant inspiratory oxygen fraction using technetium 99m radionuclide angiography. Spontaneous ventilation induced a significant decrease in left ventricular ejection fraction from 54.5 +/- 12.4 to 47.0 +/- 13% (p < 0.01). Inspiratory pressure support induced a slight but non-significant decrease in left ventricular ejection fraction from 55.0 +/- 12.1 to 50.3 +/- 12.4%. Left ventricular ejection fraction was homogeneously reduced by spontaneous ventilation without patent regional wall motion abnormalities of the left ventricle. Myocardial 201thallium imaging performed 15 min after weaning showed a normal perfusion in the left ventricle anterior and posterior free wall. CONCLUSION: Weaning of patients suffering from chronic obstructive pulmonary disease without coronary artery disease induced a significant reduction in left ventricular ejection fraction. The non significant decrease in left ventricular ejection fraction observed with inspiratory pressure support suggested that our results might be explained by a weaning induced increase in afterload.

Acute Disease↗
PubMed1993

Arterial hemodynamics and cardiac effects of enoximone, dobutamine, and their combination in severe heart failure.

The acute systemic and regional hemodynamic effects of dobutamine (5, 10, and 15 micrograms/kg/min intravenously), of enoximone (1, 1.5, and 2 mg/kg intravenously), and of the dobutamine-enoximone combination were compared in eight patients with severe congestive heart failure. Dobutamine and enoximone similarly and dose-dependently increased cardiac index and decreased systemic vascular resistance, right atrial pressure, and mean capillary wedge pressure. Dobutamine, but not enoximone, increased heart rate after 10 and 15 micrograms/kg/min. The combination of the two drugs caused a greater increase in cardiac index and a greater decrease in total peripheral resistance than did each drug alone. In the forearm vascular bed, brachial blood flow and brachial artery diameter were increased by enoximone significantly and dose-dependently and by dobutamine only at 5 micrograms/kg/min. Finally, the combination of the two drugs increased brachial blood flow but not brachial artery diameter to a larger extent than enoximone alone. Hepatosplanchnic and renal blood flows were not altered by any of the treatments. These results indicate that (1) enoximone exerts a significantly greater muscular vasodilator action than dobutamine; (2) the dobutamine-enoximone combination potentiates the systemic and brachial vasodilator effects of each drug; and (3) high doses of dobutamine (10 and 15 micrograms/kg/min) improve hemodynamics through their positive inotropic and chronotropic effects, whereas at low doses (5 micrograms/kg/min) a peripheral vasodilation also contributes.

Adult↗
PubMed1993

Cardiac index vs oxygen-derived parameters for rational use of dobutamine in patients with congestive heart failure.

In patients with congestive heart failure (CHF), catecholaminergic agents may exert thermogenic effects that limit their beneficial effects in terms of global tissue oxygenation. Oxygen extraction ratio (O2ER) or mixed venous blood saturation (SvO2) might take into account better than cardiac index (CI) the resultant effect of such agents on peripheral oxygenation. We tested this hypothesis in a series of 20 patients with severe CHF and normal blood lactate levels undergoing pulmonary artery catheterization and receiving incremental doses of dobutamine: 0 (Do), 5 (D5), 10 (D10), and 15 micrograms/kg/min (D15). A significant dose-effect relationship (p < 0.01) was found between dose of dobutamine and CI (CI = 0.06 dose + 1.82). By contrast, no dose-effect relationship was observed between dobutamine dose and either O2ER or SvO2. Indeed, a biphasic profile was observed for O2ER and SvO2. From D0 to D10, O2ER decreased (from 45 +/- 6 to 35 +/- 7 percent) and SvO2 increased (from 52 +/- 7 to 62 +/- 7 percent). From D10 to D15, no further change was observed for both parameters. This latter finding was related to a significant increase in VO2 at D15 (p < 0.01). In these normolactatemic patients with unchanged VO2 from D0 to D10 while DO2 linearly increased (from D0 to D15), the increase in VO2 at D15 was probably due to an increase in oxygen demand induced by the drug. Our results suggest that dobutamine at a dose of 15 micrograms/kg/min can induce an increase in O2 demand that might offset the improvement in CI. Thus, in patients with CHF, oxygen-derived parameters such as O2ER and SvO2 should be more appropriate than CI to assess the efficacy of dobutamine.

Adult↗
PubMed1993

Cardiorespiratory effects of pressure-controlled ventilation with and without inverse ratio in the adult respiratory distress syndrome.

To assess the cardiorespiratory effects of pressure-controlled ventilation (PCV) and pressure-controlled inverse ratio ventilation (PC-IRV), we compared pressure-controlled ventilation with an inspiratory-to-expiratory time ratio (I/E) of 1/2 (PCV) and of 2/1 (PC-IRV) to volume-controlled ventilation (VCV) with an I/E of 1/2 in 10 patients suffering from the adult respiratory distress syndrome. In all modes, the inspiratory oxygen fraction, tidal volume, respiratory rate, and total positive end-expiratory pressure (PEEPt = applied PEEP + intrinsic PEEP) were kept constant. Each ventilatory mode was applied for 1 h in a randomized order. No significant differences in PaO2 were observed among the three modes. The PaCO2 was lower (p < 0.05) in PC-IRV (39 +/- 4 mm Hg) than in PCV (43 +/- 5 mm Hg) and in VCV (45 +/- 5 mm Hg). The peak airway pressure was significantly lower in PC-IRV than in PCV (p < 0.05) and in PCV than in VCV (p < 0.05), but plateau pressure was not different in the 3 modes. The mean airway pressure (mPaw) was significantly higher (p < 0.05) in PC-IRV (21.4 +/- 0.7 cm H2O) than in PCV (17.1 +/- 0.7 cm H2O) and VCV (16.4 +/- 0.5 cm H2O). As a consequence of this increased mPaw, PC-IRV induced a decrease in cardiac index (CI) (3.3 +/- 0.2 vs 3.7 +/- 0.2 L/min/m2 in VCV; p < 0.05) and hence in oxygen delivery (DO2) (424 +/- 28 vs 469 +/- 38 ml/min/m2 in VCV; p < 0.05). Our results suggest that neither PCV nor PC-IRV bring any benefit over VCV in terms of arterial oxygenation. Moreover, the increase in mPaw induced by PC-IRV may be deleterious to the CI and DO2.

Adult↗
PubMed1992

Bedside evaluation of the resistance of large and medium pulmonary veins in various lung diseases.

To evaluate the contribution of large and medium pulmonary veins to the total pulmonary vascular resistance in various human lung diseases, we compared in 64 patients the pulmonary arterial proximal wedge pressure (Ppw), obtained when the balloon of a 7F pulmonary artery catheter was inflated with 1.5 ml air, with the distal wedge pressure (Pdw), obtained after the tip of the catheter was advanced until wedged in a small artery without balloon inflation. Ppw, reflecting the pressure in a large pulmonary vein, approximates the left atrial pressure, whereas Pdw reflects the pressure in a smaller pulmonary vein. Pdw was greater than Ppw in all 64 patients. The Pdw-Ppw gradient was 1.1 +/- 0.5 mmHg in nine patients with normal lungs and was significantly higher in 13 patients with chronic congestive heart failure (3.8 +/- 0.8 mmHg, P less than 0.01) and in 22 patients with adult respiratory distress syndrome (3.8 +/- 0.8 mmHg; P less than 0.01), but not in 20 patients with chronic obstructive pulmonary disease (1.8 +/- 0.7 mmHg). The distribution of the pulmonary vascular resistance was clearly different among the four groups. The fraction of the total pulmonary vascular resistance attributable to large and medium pulmonary veins was significantly increased (P less than 0.01) in adult respiratory distress syndrome (27.5 +/- 12%) and cardiac patients (27.5 +/- 9%) compared with patients with chronic obstructive pulmonary disease (13 +/- 5%) and normal lungs (13.5 +/- 6%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effects of cardiovascular drugs on oxygen consumption/oxygen delivery relationship in patients with congestive heart failure.

The oxygen consumption (VO2)/oxygen delivery (DO2) relationship was analyzed in ten patients with severe congestive heart failure (CHF) and normal blood lactate levels. First dobutamine and then enoximone, after a washout period, were administered to each patient to increase cardiac output by at least 15 percent. Similar increases in DO2 were obtained with both drugs: from 285 +/- 46 to 393 +/- 87 ml/min/m2 for dobutamine, and from 285 +/- 54 to 392 +/- 99 ml/min/m2 for enoximone. However, while VO2 did not change (132 +/- 24 vs 132 +/- 21 ml/min/m2) (VO2/DO2 independency) with a dobutamine infusion (mean dose of 10 +/- 2 micrograms/kg/min), a significant increase in VO2 from 134 +/- 22 to 157 +/- 21 ml/min/m2 was observed with a bolus infusion of enoximone (mean dose of 1.7 +/- 0.5 mg/kg). These results, observed in patients with CHF without patent oxygen debt, suggest that an artefactual VO2/DO2 dependency might be induced by the cardiovascular drug used to elevate DO2, probably because of a drug-induced oxygen demand increase.

Acute Disease↗
PubMed1991

[Demonstration of tissue hypoxia due to defective peripheral extraction of oxygen (O2) during brain death].

Adequate oxygenation of potentially transplantable tissues must be maintained in patients in a state of cerebral death. An analysis of the relationship between oxygen consumption and arterial oxygen supply shows that proven tissue hypoxia occurs associated with high lactate in almost all patients in a state of cerebral death, even before haemodynamic parameters (blood pressure, heart rate) reach alarming levels. This tissue hypoxia, which exists even though arterial supply remains high, would suggest that there is a defect in peripheral oxygen extraction during the state of cerebral death. Intensive units should take this into account when maintaining these patients.

Adult↗