Biomedical subjects

Patrick Wouters

Publications and source records attributed to Patrick Wouters.

7 recordsLinked to original sources

PubMed2006

Comparative study of donor lung injury in heart-beating versus non-heart-beating donors.

OBJECTIVE: The use of non-heart-beating donors (NHBD) has been advocated as an alternative to overcome the critical organ shortage in lung transplantation despite the warm ischemic period that may result in primary graft dysfunction. On the contrary, brain death in the heart-beating donor (HBD) may be an underestimated risk factor for donor lung injury. We postulated that 60 min of warm ischemia in the NHBD is less detrimental to the lung than the pathophysiological changes after brain death in the HBD. In this study we compared the quality of lungs from HBD versus NHBD in an isolated reperfusion model. METHODS: Pigs (n=10 per group) were divided into three groups. In group I (HBD), brain death was induced by acute inflation of an intracranial epidural balloon catheter. In group II (CONTROL), the balloon was not inflated. In group III (NHBD), cardiac arrest was induced by myocardial fibrillation. After 5 h of in situ mechanical ventilation, lungs in HBD and CONTROL were preserved with a cold antegrade flush. In NHBD, unflushed grafts were explanted after 1 h of warm ischemia and 4 h of topical cooling in the cadaver. Graft performance was evaluated during 1 h in an isolated ventilation and reperfusion model. Extravascular lung water content (EVLW) was calculated. All data are reported as mean+/-SEM. RESULTS: A significant autonomic storm was observed in HBD following balloon inflation. During ex vivo assessment, pulmonary vascular resistance (PVR) at 60 min in HBD (2634+/-371 dynes cm(-5)) was significantly higher as compared with that of CONTROL and NHBD (1894+/-137 dynes s cm(-5) and 1268+/-111 dynes s cm(-5), respectively; p<0.05). Plateau airway pressure (Plateau AwP) was also higher in HBD (17+/-1cmH2O) compared with that of CONTROL (12+/-1 cmH2O; p<0.05) and NHBD (14+/-1 cmH2O; not significant). No significant differences were observed between HBD, CONTROL and NHBD in EVLW (79+/-1%, 79+/-0% and 78+/-1%, respectively), and in PO2/FiO2 (564+/-58 mmHg, 622+/-14 mmHg and 578+/-26 mmHg, respectively). CONCLUSIONS: These data indicate that 1-h warm ischemic lungs in our model are less susceptible to ischemia-reperfusion injury than lungs retrieved 5 h after brain death. This study further supports the use of lungs from NHBD for pulmonary transplantation.

Airway Resistance↗

PubMed2006

Performance analysis of interactive multimodal CME retraining on attitude toward and application of OPCAB.

OBJECTIVE: The transfer of tacit and codified knowledge on a surgical technique is studied in a consecutive cohort of teams participating in interactive multimodal continuing medical education (CME) retraining in off-pump coronary artery bypass (OPCAB). METHODS: Fifty teams of 1.3 +/- 0.5 surgeons and 1.1 +/- 1.9 anesthetists visited 2.2 +/- 0.7 days. Variables describe the pre-visit cardiac activity and OPCAB attitude, complexity score (10 frequently cited complexity criteria), application, and conversion rate. The multimodal approach to knowledge transfer included interactive discussions (commitment; resistances; levers and process of change; methods; outcome; resource optimization), active participation in 3.8 +/- 1.3 unselected cases (anchor-stitch, enucleation techniques), low-fidelity bench model (shunt placement, anastomotic technique), and CD-ROM. Exit end points included OPCAB attitude and complexity score. Late end points (3 months) included OPCAB attitude, complexity score, and application rate. RESULTS: OPCAB was considered, upon exit, beneficial for all patients by 90% of the teams (versus 29 % pre-visit), but by only 62 % of the teams at 3 months. The complexity score downgraded at exit from 3.6 +/- 2 (pre-visit) to 1.2 +/- 1 (P <.001) but increased again at 3 months to 1.6 +/- 1 (P =.001 versus pre-visit and P =.001 versus exit). The 3-month OPCAB rate of the surgeons was 49% +/- 32% versus 23% +/- 28% pre-visit (P <.0001). This was influenced by the pre-visit OPCAB rate and education, as well as by the post-visit changes in complexity scores and attitude. The conversion rate toward cardiopulmonary bypass improved from 3.5% +/- 5% (pre-visit) to 1.3% +/- 3% (3 months, P =.006). CONCLUSIONS: The multimodal OPCAB re-training resulted in a substantial increase of the application, concomitant with a decrease in conversion. The positive impact on attitude and complexity score, at exit, was somewhat reduced in the following clinical confrontation.

Attitude of Health Personnel↗

PubMed2006

Rocuronium exacerbates mechanical ventilation-induced diaphragm dysfunction in rats.

OBJECTIVE: Nondepolarizing neuromuscular blocking agents are commonly used in the intensive care setting, but they have occasionally been associated with development of myopathy. In addition, diaphragmatic atrophy and a reduction in diaphragmatic force were reported after short-term controlled mechanical ventilation in animal models. We hypothesized that infusion of rocuronium, an aminosteroidal neuromuscular blocking agent, during 24 hrs of controlled mechanical ventilation would further alter diaphragm function and would enhance activation of the ubiquitin- proteasome pathway. DESIGN: Randomized, controlled experiment. SETTING: Basic animal science laboratory. SUBJECTS: Male Wistar rats, 14 wks old. INTERVENTIONS: Rats were divided into four groups: a control group, a group of anesthetized rats breathing spontaneously for 24 hrs, and two groups submitted to mechanical ventilation for 24 hrs, receiving a continuous infusion of either 0.9% NaCl or rocuronium. MEASUREMENTS AND MAIN RESULTS: In vitro diaphragm force was decreased more significantly after 24 hrs of mechanical ventilation combined with rocuronium infusion than after mechanical ventilation alone (e.g., tetanic force, -27%; p < .001 vs. mechanical ventilation). Similarly, the decrease in diaphragm type IIx/b fiber dimensions was more pronounced after mechanical ventilation with rocuronium treatment than with saline treatment (-38% and -29%, respectively; p < .001 vs. control). Diaphragm hydroperoxide levels increased similarly in both mechanically ventilated groups. Diaphragm muscle RING-finger protein-1 (MURF-1) messenger RNA expression, an E3 ligase of the ubiquitin-proteasome pathway, increased after mechanical ventilation (+212%, p < .001 vs. control) and increased further with combination of rocuronium (+320%, p < .001 vs. control). Significant correlations were found between expression of MURF-1 messenger RNA, diaphragm force, and type IIx/b fiber dimensions. CONCLUSIONS: Infusion of rocuronium during controlled mechanical ventilation leads to further deterioration of diaphragm function, additional atrophy of type IIx/b fibers, and an increase in MURF-1 messenger RNA in the diaphragm, which suggests an activation of the ubiquitin-proteasome pathway. These findings could be important with regard to weaning failure in patients receiving this drug for prolonged periods in the intensive care unit setting.

Androstanols↗

PubMed2005

Acute hemodynamic benefit of left ventricular apex pacing in children.

BACKGROUND: Despite the fact that pacing at the right ventricular apex acutely and chronically decreases left ventricular contractile function, this pacing site is still conventionally used in adults and children. Because animal studies showed beneficial effects of left ventricular pacing, we compared the hemodynamic performance of left ventricular apex, left ventricular free wall, and right ventricular apex pacing in children. METHODS: Studies were performed in 10 children (median age, 2.5 years; range, 2 months to 17 years) undergoing surgery for congenital heart disease with normal systemic left ventricular anatomy and intraventricular conduction. High-fidelity left ventricular and arterial pressure measurements were performed during epicardial right ventricular apex and left ventricular apex and free wall pacing. RESULTS: Left ventricular apex pacing increased the maximum rate of rise of left ventricular pressure and pulse pressure significantly relative to right ventricular apex pacing (by 7.7% +/- 7.2% and 7.7% +/- 7.0%, respectively) without changes in end-diastolic left ventricular pressure. Left ventricular free wall pacing did not significantly improve hemodynamics as compared with right ventricular apex pacing. The QRS duration was not different among pacing at the three sites. CONCLUSIONS: In this short-term study left ventricular apex pacing is hemodynamically superior to right ventricular apex and left ventricular free wall pacing in children. Therefore, the left ventricular apex appears a favorable pacing site after pediatric cardiac surgery.

Adolescent↗

PubMed2004

OPCAB versus early mortality and morbidity: an issue between clinical relevance and statistical significance.

OBJECTIVE: To evaluate the impact of OPCAB on major postoperative events in a large consecutive cohort of patients, covering the complete spectrum of risk. METHODS: A consecutive series of 3333 CABG patients operated in a single institution (Jan/97-Jan/03) is analyzed after a complete (98%) midterm reengineering towards off-pump surgery (Oct/99). Patients in cardiogenic shock are excluded. The on- (N=1593) or off-pump (N=1740) datasets are comparable for most demographic and non-cardiac variability. The studied events are early mortality, early stroke, early infarct, early dialysis and hospital stay. Three methods adjust for possible patient selection: similar datasets, forced inclusion of a saturated OPCAB propensity score and finally multivariate correction. RESULTS: Non-risk adjusted. The 3-month survival was 96.7+/-0.4% (OPCAB) and 95.9+/-0.5% (ECC) (P=0.2). The 8-day freedom from stroke was 99.4+/-0.2% (OPCAB) and 98.5+/-0.3% (ECC) (P=0.004). The prevalence of dialysis was 1.67% in OPCAB and 2.27% in ECC (P=0.2). The 8-day freedom from infarct was 98.4+/-0.2% (OPCAB) and 98.3+/-0.2% (ECC) (P=0.7). The freedom from hospital discharge day 15 was 17.6+/-0.9% (OPCAB) and 18.4+/-0.8% (ECC) (P=0.001). Propensity score corrected and adjusted for event-related variability. The survival effect remained non-significant (P=0.3), also for patients with a EuroSCORE>8 (P=0.9). The stroke effect became non-significant (P=0.2), but stayed significant for patients with severe internal carotid artery stenosis (P=0.02). The dialysis-effect remained non-significant (P=0.6), also for patients with an elevated creatinine (P=0.7). The early infarct-effect remained non-significant (P=0.8), also for the female patients (P=0.8). The hospital discharge was significantly influenced by the OPCAB approach for the total group (P=0.02) as well as for the patients with EuroSCORE>8 (P=0.01). CONCLUSIONS: The observed 20% reduction of mortality, 60% reduction of stroke and 20% reduction of dialysis were partly neutralized by the adjusting methods and demand, at least, larger datasets to obtain statistical significance. Subdatasets with fewer patients but higher risk identified risk-reducing effects for stroke. Hospital stay was shortened by the OPCAB approach. The interactions between risk, number of patients and the risk-reducing effect are the cornerstones of evidence generation for the OPCAB approach. These results were obtained through a very strict reengineering and cannot be extended to all OPCAB programs.

Aged↗

PubMed2003

Remote preconditioning lessens the deterioration of pulmonary function after repeated coronary artery occlusion and reperfusion in sheep.

PURPOSE: We investigated whether remote organ preconditioning (RPC) can preserve pulmonary function following repeated myocardial ischemia/reperfusion in a model mimicking multi-vessel off-pump coronary artery bypass (OPCAB) revascularization. METHODS: Nine sheep (Group-RPC) underwent RPC by three episodes of five-minute occlusion and five-minute reperfusion of the iliac artery. Five sheep (Group-C) were time-matched controls. Afterwards, ten-minute occlusion and reperfusion of the left anterior descending, the first diagonal and the left circumflex coronary arteries were performed consecutively. Hemodynamic and respiratory parameters and arterial blood gases were measured until 120 min after the final coronary reperfusion. Anesthesia was maintained with halothane in oxygen and nitrous oxide. Animals were ventilated with a tidal volume of 15-20 mL.kg(-1) in a non-rebreathing system, and a respiratory rate 14-16 min, with 5-cm H(2)O positive end expiratory pressure after thoracotomy. RESULTS: Repeated coronary occlusion and reperfusion was associated in this experimental model with an increase in pulmonary vascular resistance (PVR) and pulmonary arterial pressure (PAP) and a decrease in PaO(2) and PaO(2)/FIO(2) in Group-C. After 120 min reperfusion, PaO(2) and PaO(2)/FIO(2) in Group-RPC were higher (192 +/- 69 mmHg and 241 +/- 78 vs 115 +/- 54 mmHg and 129 +/- 64, P < 0.05), while PVR and PAP were lower than in Group-C. At 120 min of reperfusion, PaO(2) and PaO(2)/FIO(2) were inversely correlated with PVR (P < 0.01). CONCLUSIONS: RPC by transient occlusion of the iliac artery improves lung gas exchange after repeated coronary artery occlusion and reperfusion mimicking OPCAB surgery, and preserves low PVR in sheep.

Analysis of Variance↗

PubMed2003

Long-term outcome after coronary artery bypass grafting in cardiogenic shock or cardiopulmonary resuscitation.

OBJECTIVES: Coronary artery bypass grafting carried out in patients in cardiogenic shock or receiving cardiopulmonary resuscitation is an infrequently performed procedure, disrupting the normal process with a dramatic early risk. These circumstances mandate an analysis of the benefit, including the early identification of the late survivors. METHODS: A consecutive series of patients undergoing coronary artery bypass grafting while in cardiogenic shock (n = 167) or while receiving cardiopulmonary resuscitation (n = 92) from August 1979 until August 2001 were studied by using time-related and multivariate methodologies and a common-closing-date follow-up methodology. The events leading to the preoperative condition were either a recent catheterization, recent coronary artery bypass grafting, recent percutaneous transluminal coronary angioplasty, an infarction at home, an infarction in the hospital, or an infarction after a recent infarction. RESULTS: The 1- and 10-year survival was 59% +/- 6% and 47% +/- 7%, respectively. A normal hazard of late death was observed beyond the protracted early hazard. Multivariate analysis of survival identified an increased risk in the presence of additional comorbidity, treated diabetes, a lower pH at entry into the operating theater, and the presence of triple-vessel disease. The discriminatory power for hospital mortality of the predictive variables was low (receiving operator characteristic range, 0.56-0.69). The 30-day freedom from hospital discharge alive was 33% +/- 7%. The 8-day freedom from stroke was 94% +/- 3%, and 8-day freedom from mechanical univentricular or biventricular support was 87% +/- 5%. The 10-year freedom from cardiosurgical reintervention was 90% +/- 6%. CONCLUSIONS: Coronary artery bypass grafting in cardiogenic shock or during cardiopulmonary resuscitation has an extremely high and protracted periprocedural risk but is balanced by a satisfactory late survival. An early prediction of the hospital survivors is difficult.

Adult↗