Biomedical subjects

Marc Reynaert

Publications and source records attributed to Marc Reynaert.

10 recordsLinked to original sources

PubMed2006

A multicenter randomized trial of computer-driven protocolized weaning from mechanical ventilation.

RATIONALE AND OBJECTIVES: Duration of weaning from mechanical ventilation may be reduced by the use of a systematic approach. We assessed whether a closed-loop knowledge-based algorithm introduced in a ventilator to act as a computer-driven weaning protocol can improve patient outcomes as compared with usual care. METHODS AND MEASUREMENTS: We conducted a multicenter randomized controlled study with concealed allocation to compare usual care for weaning with computer-driven weaning. The computerized protocol included an automatic gradual reduction in pressure support, automatic performance of spontaneous breathing trials (SBT), and generation of an incentive message when an SBT was successfully passed. One hundred forty-four patients were enrolled before weaning initiation. They were randomly allocated to computer-driven weaning or to physician-controlled weaning according to local guidelines. Weaning duration until successful extubation and total duration of ventilation were the primary endpoints. MAIN RESULTS: Weaning duration was reduced in the computer-driven group from a median of 5 to 3 d (p=0.01) and total duration of mechanical ventilation from 12 to 7.5 d (p=0.003). Reintubation rate did not differ (23 vs. 16%, p=0.40). Computer-driven weaning also decreased median intensive care unit (ICU) stay duration from 15.5 to 12 d (p=0.02) and caused no adverse events. The amount of sedation did not differ between groups. In the usual care group, compliance to recommended modes and to SBT was estimated, respectively, at 96 and 51%. CONCLUSIONS: The specific computer-driven system used in this study can reduce mechanical ventilation duration and ICU length of stay, as compared with a physician-controlled weaning process.

Aged↗

PubMed2005

Compartmentalization of the protease-antiprotease balance in early severe acute pancreatitis.

OBJECTIVE: To assess the balance between trypsin and protease inhibitors simultaneously in the systemic circulation and in the thoracic lymph and peritoneal exudate. METHODS: Twenty patients with early severe acute pancreatitis were studied. Enzymatically active and immunoreactive trypsin in conjunction with its major inhibitors were measured in the 3 compartments at the onset of end-organ failure(s). The molecular forms of trypsin were determined in the lymph and ascites by gel filtration chromatography to separate trypsinogen and free-and inhibitor-bound trypsin. RESULTS: Both enzymatically active trypsin and immunoreactive trypsin levels were highest in ascites and lymph compared with the systemic circulation. Intracompartmental alpha1- protease inhibitor gradient moved in the opposite direction, whereas alpha2 macroglobulin concentration was highest in ascites and lowest in the lymph. Although most of the enzymatically and immunoreactive material in ascites and lymph consisted of trypsin complexed with alpha2 macroglobulin and trypsinogen, respectively, free active trypsin was detected in more than 80% of the samples. CONCLUSIONS: In patients with early severe acute pancreatitis, there is a significant trypsinogen activation resulting in protease-antiprotease imbalance and thereby free enzymatically active trypsin in the 2 body fluid compartments in close vicinity to the inflammatory process. This may be involved in the pathophysiology of local and distant tissue damage.

Acute Disease↗

PubMed2004

Volumetric capnography as a bedside monitoring of thrombolysis in major pulmonary embolism.

OBJECTIVE: To describe the use of volumetric capnography, a plot of expired CO(2) concentration against expired volume, in monitoring fibrinolytic treatment of major pulmonary embolism. DESIGN AND SETTING: Two case reports in the emergency department of a teaching hospital. PATIENTS: Two conscious and spontaneously breathing patients (69- and 31-year-old women) with major pulmonary embolism requiring thrombolysis. Decision for thrombolysis was based on the association of right ventricular afterload on echocardiography, with respiratory failure and hypotension in the first patient, and dyspnea and hemodynamically stable parameters in the second one. INTERVENTIONS: Successive capnographic measurements were performed before, during, and after thrombolysis. Curves of volumetric capnography were obtained from a sidestream gas monitor with flow sensor and an arterial blood gas analysis for CO(2) partial pressure. MEASUREMENTS AND RESULTS: We calculated late deadspace fraction, previously suggested as the most effective capnographic parameter in the diagnosis of pulmonary embolism. Late deadspace fraction decreased in the two patients, respectively, from 64.4% to 1.1% and from 25.6% to 5.7% after thrombolysis, with a concomitant disappearance of right heart dysfunction signs on echocardiography. CONCLUSIONS: Volumetric capnography can monitor thrombolysis in major pulmonary embolism. Differences between volumetric capnography technology and the more traditional arterial to end-tidal CO(2) gradient are important to take into account for clinical application.

Adult↗

PubMed2004

Volumetric capnography as a screening test for pulmonary embolism in the emergency department.

STUDY OBJECTIVE: To compare the diagnostic performance of volumetric capnography (VCap), which is the plot of the expired CO(2) partial pressure against the expired volume during a single breath, with the PaCO(2) to end-tidal CO(2) (EtCO(2)) gradient, in the case of suspected pulmonary embolism (PE). DESIGN: Single-center, prospective study. SETTING: Emergency department of a teaching hospital. PATIENTS: A total of 45 outpatients with positive enzyme-linked immunosorbent assay d-dimer levels of > 500 ng/mL. The diagnosis of PE was confirmed in 18 outpatients according to a validated procedure based on the ventilation-perfusion lung scan and/or spiral CT scanning. INTERVENTIONS: Curves of VCap were obtained from a compact monitor connected to a computer. A sequence of four to six stable breaths allowed the calculation of the following several variables: alveolar dead space fraction; the ratio of alveolar dead space (VDalv) to airway dead space (VDaw); the VDalv to physiologic dead space (VDphys) fraction; the slope of phase 3; and the late dead space fraction (Fdlate) corresponding to the extrapolation of the capnographic curve to a volume of 15% of the predicted total lung capacity. RESULTS: The mean (+/- SD) PaCO(2)-EtCO(2) gradient was 5.3 +/- 0.7 mm Hg in the PE-positive group and 2.8 +/- 0.7 mm Hg in the PE-negative group (p = 0.019). Four variables of the VCap exhibited a statistical difference between both groups, as follows: the VDalv/VDaw fraction(;) the slope of phase 3; the VDalv/VDphys fraction; and the Fdlate, which was 8.2 +/- 3.3% vs -7.7 +/- 2.8%, respectively (p = 0.000011). The diagnostic performance expressed as the mean area under a receiver operating characteristic curve comparison was 75.9 +/- 7.4% for the PaCO(2)-EtCO(2) gradient and 87.6 +/- 4.9% for the Fdlate (p = 0.02). CONCLUSION: Fdlate, a variable of VCap, had a statistically better diagnostic performance in suspected PE than the PaCO(2)-EtCO(2) gradient. VCap is a promising computer-assisted bedside application of pulmonary pathophysiology. Future research should define the place of this technique in the diagnostic workup of PE, especially in the presence of positive d-dimers.

Breath Tests↗

PubMed2003

Comparative effects of helium-oxygen and external positive end-expiratory pressure on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in mechanically ventilated patients with chronic obstructive pulmonary disease.

OBJECTIVE: To compare the effects of He/O(2) and external PEEP (PEEPe) on intrinsic PEEP (PEEPi), respiratory mechanics, gas exchange, and ventilation/perfusion (V(A)/Q) in mechanically ventilated COPD patients. DESIGN AND SETTING: Prospective, interventional study in the intensive care unit of a university hospital. INTERVENTIONS: Ten intubated, sedated, paralyzed, mechanically ventilated COPD patients studied in the following conditions: (a) baseline settings made by clinician in charge, air/O(2), ZEEP; (b) He/O(2), ZEEP; (c) air/O(2), ZEEP; (d) air/O(2), PEEPe 80% of PEEPi. Measurements at each condition included V(A)/Q by the multiple inert gas elimination technique (MIGET). RESULTS: PEEPi and trapped gas volume were comparably reduced by He/O(2) (4.2+/-4 vs. 7.7+/-4 cmH(2)O and 98+/-82 vs. 217+/-124 ml, respectively) and PEEPe (4.4+/-1.3 vs. 7.8+/-3.6 cmH(2)O and 120+/-107 vs. 216+/-115 ml, respectively). He/O(2) reduced inspiratory and expiratory respiratory system resistance (15.5+/-4.4 vs. 20.7+/-6.9 and 19+/-9 vs. 28.8+/-15 cmH(2)O l(-1)s(-1), respectively) and plateau pressure (13+/-4 vs. 17+/-6 cmH(2)O). PEEPe increased airway pressures, including total PEEP, and elastance. PaO(2)/FIO(2) was slightly reduced by He/O(2) (225+/-83 vs. 245+/-82) without significant V(A)/Q change. CONCLUSIONS: He/O(2) and PEEPe comparably reduced PEEPi and trapped gas volume. However, He/O(2) decreased airway resistance and intrathoracic pressures, at a small cost in arterial oxygenation. He/O(2) could offer an attractive option in COPD patients with PEEPi/dynamic hyperinflation.

Aged↗

PubMed2003

Effects of helium-oxygen on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in a porcine model of stable methacholine-induced bronchospasm.

OBJECTIVE: To explore the consequences of helium/oxygen (He/O(2)) inhalation on respiratory mechanics, gas exchange, and ventilation-perfusion (VA/Q) relationships in an animal model of severe induced bronchospasm during mechanical ventilation. DESIGN: Prospective, interventional study. SETTING: Experimental animal laboratory, university hospital. INTERVENTIONS: Seven piglets were anesthetized, paralyzed, and mechanically ventilated, with all ventilator settings remaining constant throughout the protocol. Acute stable bronchospasm was obtained through continuous aerosolization of methacholine. Once steady-state was achieved, the animals successively breathed air/O(2) and He/O(2) (FIO(2) 0.3), or inversely, in random order. Measurements were taken at baseline, during bronchospasm, and after 30 min of He/O(2) inhalation. RESULTS: Bronchospasm increased lung peak inspiratory pressure (49+/-6.9 vs 18+/-1 cm H(2)O, P<0.001), lung resistance (22.7+/-1.5 vs 6.8+/-1.5 cm H(2)O x l(-1).s, P<0.001), dynamic elastance (76+/-11.2 vs 22.8+/-4.1 cm H(2)O x l(-1), P<0.001), and work of breathing (1.51+/-0.26 vs 0.47+/-0.08, P<0.001). Arterial pH decreased (7.47+/-0.06 vs 7.32+/-0.06, P<0.001), PaCO(2) increased, and PaO(2) decreased. Multiple inert gas elimination showed an absence of shunt, substantial increases in perfusion to low VA/Q regions, and dispersion of VA/Q distribution. He/O(2) reduced lung resistance and work of breathing, and worsened hypercapnia and respiratory acidosis. CONCLUSIONS: In this model, while He/O(2) improved respiratory mechanics and reduced work of breathing, hypercapnia and respiratory acidosis increased. Close attention should be paid to monitoring arterial blood gases when He/O(2) is used in mechanically ventilated acute severe asthma.

Acute Disease↗

PubMed2003

Respiratory muscle workload in intubated, spontaneously breathing patients without COPD: pressure support vs proportional assist ventilation.

OBJECTIVE: To compare the respiratory muscle workload associated with pressure support ventilation (PSV) and proportional assist ventilation (PAV) in intubated and spontaneously breathing patients without COPD. DESIGN AND SETTING: Prospective study, intensive care unit university hospital. INTERVENTIONS: Twenty intubated patients, during early weaning, PSV settings made by clinician in charge of the patient, and two levels of PAV, set to counterbalance 80% (PAV 80) and 50% (PAV 50) of both elastic and resistive loads, respectively. The patients were ventilated in the following order: 1) PSV; 2) PAV 50 or PAV 80; 3) PSV; 4) PAV 80 or PAV 50; 5) PSV. PSV settings were kept constant. MEASUREMENTS: Arterial blood gases, breathing pattern and respiratory effort parameters at the end of each of the five steps. MAIN RESULTS: PSV and PAV 80 had the same effects on work of breathing (WOB). The pressure-time product (PTP) was significantly higher during PAV 80 than during PSV (90+/-76 and 61+/-56 cmH(2)O.s.min(-1), respectively, P <0.05). Tidal volume was comparable, albeit more variable with PAV 80 than with PSV (variation coefficient, 43% vs 25%, respectively, P <0.05). PAV 50 entailed a higher respiratory rate, lower tidal volume, and higher WOB and PTP than PSV and PAV 80. PaO(2)/FiO(2) and SaO(2) were lower with PAV 50 than with PSV and PAV 80. CONCLUSION: In a group of intubated spontaneously breathing non-COPD patients, PAV 80 and PSV were associated with comparable levels WOB, whereas PTP was higher during PAV 80. PAV 50 provided insufficient respiratory assistance.

Adult↗

PubMed2003

Helium-oxygen versus air-oxygen noninvasive pressure support in decompensated chronic obstructive disease: A prospective, multicenter study.

OBJECTIVE: To study whether noninvasive pressure support ventilation (NIPSV) with helium/oxygen (He/oxygen), which can reduce dyspnea, PaCO2, and work of breathing more than NIPSV with air/oxygen in decompensated chronic obstructive pulmonary disease, could have beneficial consequences on outcome and hospitalization costs. DESIGN: Prospective, randomized, multicenter study. SETTING: Intensive care units of three tertiary care university hospitals. PATIENTS: All patients with chronic obstructive pulmonary disease admitted to the intensive care units for NIPSV during a 24-month period. INTERVENTIONS: Patients were randomized to NIPSV with air/oxygen or He/oxygen. NIPSV settings, number of daily trials, decision to intubate, and intensive care unit and hospital discharge criteria followed standard practice guidelines. RESULTS: A total of 123 patients (male/female ratio, 71:52; age, 71 +/- 10 yrs, Acute Physiology and Chronic Health Evaluation II, 17 +/- 4) were included. Intubation rate (air/oxygen 20% vs. He/oxygen 13%) and length of stay in the intensive care unit (air/oxygen 6.2 +/- 5.6 vs. He/oxygen 5.1 +/- 4 days) were comparable. The post-intensive care unit hospital stay was lower with He/oxygen (air/oxygen 19 +/- 12 vs. He/oxygen 13 +/- 6 days, p < .002). Cost of NIPSV gases was higher with He/oxygen, but total hospitalization costs were lower by $3,348 per patient with He/oxygen. No complications were associated with the use of He/oxygen. CONCLUSION: He/oxygen did not significantly reduce intubation rate or intensive care unit stay, but hospital stay was shorter and total costs were lower. He/oxygen NIPSV can be safely administered and could prove to be a cost-effective strategy.

APACHE↗

PubMed2002

An improved porcine model of stable methacholine-induced bronchospasm.

OBJECTIVE: To validate an animal model replicating the pathophysiological characteristics of severe induced bronchospasm observed in humans, with a high level of stability permitting measurements such as the assessment of ventilation-perfusion relationships with the multiple inert gas elimination technique. DESIGN AND SETTING: Experimental study in an animal research laboratory. SUBJECTS: 13 piglets (age 3-4 months) were studied and 7 underwent the complete protocol INTERVENTIONS: The animals were anesthetized and paralyzed. Mechanical ventilation was initiated in a volume-controlled mode. Ventilatory parameters were adjusted to obtain normocapnia and were maintained constant during the bronchospasm. Methacholine was administered via a synchronized nebulizer and progressively adjusted to obtain a stable twofold increase in peak inspiratory pressure. MEASUREMENTS AND RESULTS: Cardiopulmonary physiological data including assessment of lung mechanics and measurement of ventilation-perfusion relationships were obtained before and during the bronchospasm. Peak inspiratory pressure increased from 19.7+/-2.9 to 44.4+/-7.1 cmH(2)O during the bronchospasm. The latter remained stable over 2 h. Respiratory mechanics, gas exchange, and ventilation-perfusion distribution changes typical of those observed in severe bronchospasm in humans were observed in all animals. CONCLUSIONS: The present experimental model replicates some of the physiopathological characteristics of severe human bronchospasm, and its stability should facilitate studies of the effects of different ventilatory modes in the setting of acute severe asthma.

Animals↗

PubMed2002

Effervescent paracetamol poisoning: a case report.

Severe poisoning with effervescent paracetamol tablets has never been described in the literature. Indeed, the effervescent formulation contains high amounts of sodium and bicarbonate, both responsible for important emetic properties in the case of massive ingestion. Moreover, dissolving more than 6-8 tablets in the same glass appears to be difficult. We report a well-documented case of a patient with potentially hepatotoxic serum levels after the ingestion of 16 g effervescent paracetamol, apparently without vomiting. We show that the difficulties of a massive oral intake may be overcome by a slow intake. Nevertheless, this case report does not modify the important assertion that effervescent paracetamol use could limit the risk of life-threatening intoxication by a single massive acute overdose.

Acetaminophen↗