Patrick Wouters

Patellar tendinitis: pathology and results of treatment.

Patellar tendinitis can be considered as an overload lesion in athletes. Anatomical pathology reveals focal degeneration and microtearing at predisposed areas near the insertion of the quadriceps or patellar tendon. Thie prognosis and treatment are dependent on the stage of the affection. A program of conservative treatment is effective in the early stages of the disease but it fails in a high proportion (16/38) of cases in the later stages. Surgery directed towards the tendon, rather than a bony procedure, yielded favourable results in 27 out of 29 patients.

Long-chain triglycerides improve recovery from myocardial stunning in conscious dogs.

OBJECTIVESnFree fatty acid (FFA) oxidation is depressed in the postischaemic stunned myocardium and recovers in parallel with the normalization of contractile performance. Assuming a causal role for this metabolic disturbance in the pathogenesis of stunning, we questioned whether exogenous administration of high dose triglycerides during reperfusion of postischaemic myocardium, could improve its functional recovery.nnnMETHODSnThirteen dogs were chronically instrumented to measure global and regional haemodynamics and to produce a 10 min episode of regional myocardial ischaemia. In 7 dogs, Intralipid 20% was administered i.v. during the reperfusion phase. Contractile recovery of stunned myocardium was compared with control saline treatments. The series were repeated in another 6 animals, but oxfenicine (CPT I inhibitor) preceeded Intralipid during reperfusion.nnnRESULTSnContractile recovery of stunned myocardium was faster and more extensive when Intralipid was administered during reperfusion than with saline treatment (wall thickening fraction 86 +/- 6% of preischaemic controls versus 52 +/- 11% at 90 min post-reperfusion; P < 0.05). Oxfenicine pretreatment completely abolished this beneficial effect.nnnCONCLUSIONSnExogenous administration of triglycerides during reperfusion of postischaemic myocardium improves functional recovery from stunning. This beneficial effect most likely operates through enhanced FFA availability and/or oxidation since it could be abolished by selective inhibition of the carnitine palmitoyl I enzyme.

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.

Light anaesthesia with propofol for paediatric MRI

Anaesthetic techniques and monitoring equipment may interfere with the technical demands of magnetic resonance imaging. The purpose of this study was to evaluate the safety and efficacy of a light anaesthetic technique with intravenous propofol in nonintubated children. In 20 neuropaediatric patients sedation was induced with propofol 1 mg.kg−1, followed by a continuous infusion titrated to produce adequate immobilisation. Oxygen, 4 l.min−1, was administrated by paediatric face mask. Respiratory rate, end‐tidal carbon dioxide tension and oxygen saturation were continuously monitored. In 10 patients capillary blood gas tensions were determined 3 and 20 min after the procedure. Data are reported as mean (SD) and the mean (SD) total propofol dose was 5 (2) mg.kg−1.h−1. Oxygen saturation remained constantly higher than 96% in all patients. End‐tidal carbon dioxide tension varied between 35 (7) mmHg 3 min after induction, and 41 (6) mmHg 30 min after the start of the procedure. End‐tidal to capillary PCO2 difference was 4 (3) mmHg. Within 20 min after the end of the procedure all patients were fit for dismissal to the ward. One imaging sequence out of 49 was repeated because of movement artefacts. In conclusion, intravenous propofol sedation appears to be a safe and reliable technique for paediatric sedation during magnetic resonance imaging.

Effects of lipids on the functional and metabolic recovery from global myocardial stunning in isolated rabbit hearts

OBJECTIVESnHigh concentrations of free fatty acids may increase myocardial ischaemic damage. However, the administration of lipid emulsions during reperfusion improves the functional recovery of stunned myocardium. From this apparent controversy we hypothesise that the effect of lipids is related to the time of its administration: we compared the effects of pre- and post-ischaemic administration of Intralipid((R)) on stunned myocardium. We also examined the role of fatty acids and phospholipids, respectively, in the effect of lipid emulsions on stunned myocardium.nnnMETHODSnMyocardial stunning was produced by 15 min of ischaemia and 90 min of reperfusion in isolated blood perfused rabbit hearts. Intralipid((R)) was administered either prior to ischaemia or during reperfusion. Left ventricular pressure (LVP) and its first derivative (LVdP/dt) were measured to assess functional recovery. High energy phosphates were measured with HPLC. The effects of linoleic acid, phosphatidylcholine and their combination were also studied.nnnRESULTSnOnly when Intralipid((R)) was administered during reperfusion, it improved recovery from contractile function and increased high energy phosphate content in globally stunned myocardium. Both linoleic acid and phosphatidylcholine significantly improved myocardial function in stunned myocardium.nnnCONCLUSIONSnThe effect of lipids on the contractile performance and metabolic state of stunned myocardium depends mainly on the timing of its administration with regard to the ischaemia/reperfusion event. Both free fatty acids and phospholipids contribute to the beneficial effect of lipid emulsions on functional recovery of stunned myocardium.

Infusions of rocuronium and cisatracurium exert different effects on rat diaphragm function.

ObjectiveAminosteroidal and benzylisoquinoline neuromuscular blocking agents are used in the intensive care unit to facilitate mechanical ventilation. The use of these agents has been associated with development of critical illness myopathy; however, the relative frequency of myopathy development among agents is not known. The aim of our study was to compare the effects of 24u202fh infusion of rocuronium or cisatracurium on the diaphragm in mechanically ventilated rats.DesignRandomized, controlled experiment.SettingBasic animal science laboratory.SubjectsMale Wistar rats, 14 weeks old.InterventionsRats were divided into four groups to receive either saline, rocuronium (low dose) or cisatracurium (low or high dose).Measurements and resultsAfter 24u202fh, in vitro diaphragm tetanic force was decreased after rocuronium (–33% vs. saline), while the force was more preserved after cisatracurium, even in the high-dose group. Cross-sectional areas of the different diaphragm and gastrocnemius fibers were unaltered. Diaphragmatic MURF-1 mRNA was increased after rocuronium (+44% vs. saline), while unchanged in both cisatracurium groups. Calpain activity was increased after rocuronium (+75% vs. saline) and unchanged in the cisatracurium groups. MURF-1 mRNA expression and calpain activity were negatively correlated with diaphragm force.ConclusionsCisatracurium infusion during controlled mechanical ventilation exerted less detrimental effects on diaphragm function and proteolytic activity than infusion of rocuronium, even with the higher effective dose. These data suggest that increased calpain activity and increased activation of the ubiquitin proteasome system play axa0role in the different effects of these agents.

The challenge of departmental quality control in the reengineering towards off-pump coronary artery bypass grafting.

OBJECTIVEnOff pump coronary surgery is a major reengineering effort of the surgical systems. There are no perfect tools available to guide every centre in the confrontation with the complete spectrum of risk and the limited number of events. This study analyses the use of a hospital mortality risk-stratifying system in the complete shift towards off-pump CABG.nnnMETHODSnAll 535 off-pump CABG patients from January 1997 till September 2000 underwent a comparison of their hospital mortality versus the EuroSCORE predictions. The mean risk predicted by the EuroSCORE was 4.5+/-3% (range 0-14) and the mean age was 65+/-10 years (range 36-89). The series includes 23 repeat procedures, also 77 patients with per oral or insulin-treated diabetes. The number of distal anastomoses was 2.5+/-1 and of arterial grafts 1.3+/-0.6.nnnRESULTSnThe observed hospital mortality was 15 patients, 2.8% (Fisher exact test P=0.19 versus the EuroSCORE). The 1 and 3 month Kaplan-Meier survival, irrespective from hospital discharge, was 97.4+/-0.7 and 97.2+/-0.7%, respectively. A cumulative risk-adjusted mortality plot is constructed. The area under the ROC curve was 0.886. A stepwise sampling of patients according to increasing risk identified the difference between the EuroSCORE-predicted and observed hospital mortality for the complete spectrum of risk. The P value of this difference was 0.06 for the grouping including all patients from 0-5% risk (78% reduction), 0.04 for the grouping 0-8% risk (61% reduction), and 0.05 for the grouping 0-11% risk (52% reduction of risk). The loss of statistical significant difference was due to the inclusion of the patients at extremely high risk.nnnCONCLUSIONnA hospital mortality risk-stratifying system can provide guidance but different and in depth approaches are mandatory to improve the insight, certainly in the presence of a large spectrum of risk.

Load-sensitivity of regional tissue deformation in the right ventricle: isovolumic versus ejection-phase indices of contractility

Objective: Doppler myocardial imaging is increasingly being used to evaluate regional and global cardiac function. Quantitative measurements of tissue deformation obtained during ejection as well as isovolumic contraction have been proposed as new indices of contractility; however, their load-sensitivity remains a matter of controversy. Maximum strain rate (SRmax) and isovolumic strain acceleration (ISAmax) were compared with regard to sensitivity for inotropic state, heart rate and loading conditions in the right ventricle (RV), using pressure-volume analysis as the reference method. Design: Prospective animal study. Setting: University hospital laboratory. Interventions: RV contractility was measured at baseline, after inotropic modulation with esmolol and dobutamine, at different atrial pacing rates and during controlled alterations of RV preload and afterload. Main outcome measures: RV contractility was assessed with the slope (Mw) of preload recruitable stroke work and longitudinal SRmax and ISAmax. Results: SRmax and ISAmax reflected the drug-induced changes in contractility, while only ISAmax increased with higher pacing rates. Acute lowering of RV preload did not affect either of the indices studied. In contrast, an increase in RV afterload consistently decreased SRmax (from 1.05 (SD 0.41) to 0.73 (SD 0.26) s-1,pu200a=u200a0.03) but had variable effects on ISAmax and Mw. However, a significant correlation was found between proportional changes in ISAmax and Mw during high-afterload conditions (r2u200a=u200a0.89, pu200a=u200a0.005). Conclusions: Both SRmax and ISAmax reflected changes in RV contractility. ISAmax was less sensitive to changes in RV afterload than SRmax and may therefore be a more robust index of global RV contractility.

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

PurposeWe 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.MethodsNine 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 H2O positive end expiratory pressure after thoracotomy.ResultsRepeated 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 PaO2 and PaO2/FlO2 in Group-C. After 120 min reperfusion, PaO2 and PaO2/FlO2 in Group-RPC were higher ( 192 ± 69 mmHg and 241 ± 78vs I 15 ± 54 mmHg and 129 ± 64,P < 0.05), while PVR and PAP were lower than in Group-C. At 120 min of reperfusion, PaO2 and PaO2/FlO2 were inversely correlated with PVR(P < 0.01).ConclusionsRPC 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.RésuméObjectifNous avons vérifié si ie préconditionnement éioigné d’un organe (PEO) peut préserver ia fonction puimonaire à ia suite d’ischémie/reperfusion myocardique répétée chez un modèie imitant la revascuiarisation d’un pontage aortocoronarien plurivasculaire à cœur battant (PACCB)MéthodeNeuf moutons (Groupe PEO) ont subi un PEO en trois épisodes d’occlusion de cinq minutes suivis de reperfusion de cinq minutes de l’artère iliaque. Cinq moutons (Groupe T) ont constitué le groupe témoin apparié dans le temps. Par la suite, nous avons réalisé successivement l’occlusion et la reperfusion, en dix minutes, des artères coronaires interventriculaire antérieure, première diagonale et circonflexe. Les paramètres hémodynamiques et respiratoires et la gazométrie du sang artériel ont été mesurés jusqu’à 120 min après la reperfusion coronaire finale. L’anesthésie a été maintenue avec de l’halothane dans un mélange d’oxygène et de protoxyde d’azote. Les animaux ont été ventilés selon un volume de 15- 20 mL·kg−1 avec un système sans réinspiration, et une fréquence respiratoire de 14–16 min selon une pression positive en fin d’expiration de 5 cm de H2O après la thoracotomie.RésultatsDans ce modèle expérimental, l’occlusion et la reperfusion coronaires répétées ont été associées à une augmentation de la résistance vasculaire pulmonaire (RVP) et de la tension artérielle pulmonaire (TAP) ainsi qu’à une baisse de la PaO2 et de la PaO2/ElO2 dans le Groupe T. Dans le Groupe PEO, après 120 min de reperfusion, la PaO2 et la PaO2/FIO2 étaient plus élevées (192 ± 69 mmHg et 241 ± 78 vs 115 ± 54 mmHg et 129 ± 64, P < 0,05), tandis que la RVP et la TAP étaient plus faibles que dans le Groupe T.À 120 min de reperfusion, la PaO2 et la PaO2/FlO2 étaient en corrélation inverse avec la RVP(P < 0,01).ConclusionLe PEO par occlusion transitoire de l’artère iliaque améliore les échanges gazeux pulmonaires après l’occlusion et la reperfusion répétée de l’artère coronaire simulant un PACCB et il maintien une faible RVP.

Thoracic epidural anesthesia impairs the hemodynamic response to acute pulmonary hypertension by deteriorating right ventricular-pulmonary arterial coupling.

Objective: Thoracic epidural anesthesia is increasingly used in critically ill patients. This analgesic technique was shown to decrease left ventricular contractility, but effects on right ventricular function have not been reported. A deterioration of right ventricular performance may be clinically relevant for patients with acute pulmonary hypertension, in which right ventricular function is an important determinant of outcome. In the present study, we tested the hypothesis that thoracic epidural anesthesia decreases right ventricular contractility and limits its capacity to tolerate pulmonary hypertension. Design: Prospective, placebo‐controlled study using an established model of acute pulmonary hypertension. Setting: University hospital laboratory. Subjects: A total of 14 pigs (mean weight, 35 ± 2 kg). Interventions: After instrumentation with an epidural catheter, biventricular conductance catheters, a pulmonary flow probe, and a high‐fidelity pulmonary pressure catheter, seven pigs received thoracic epidural anesthesia and seven pigs served as control. Hemodynamic measurements were performed in baseline conditions and after induction of pulmonary hypertension via hypoxic pulmonary vasoconstriction (Fio2 of 0.15). Measurements and Main Results: Ventricular contractility was assessed using load‐ and heart rate–independent variables. Right ventricular afterload was characterized with instantaneous pressure–flow measurements. In baseline conditions, thoracic epidural anesthesia decreased left but not right ventricular contractility. In untreated animals, pulmonary hypertension was associated with an increase in right ventricular contractility and cardiac output. Pretreatment with thoracic epidural anesthesia completely abolished the positive inotropic response to acute pulmonary hypertension. As a result, ventriculo‐vascular coupling between the right ventricle and pulmonary–arterial system deteriorated, and cardiac output was significantly lower in animals with thoracic epidural anesthesia than in untreated controls during hypoxia‐induced pulmonary hypertension. Conclusions: Thoracic epidural anesthesia inhibits the native positive inotropic response of the right ventricle to increased afterload and deteriorates the hemodynamic effects of acute pulmonary hypertension.