Michael D. Sharpe

Intraaortic balloon counterpulsation improves right ventricular failure resulting from pressure overload.

BACKGROUND Right ventricular (RV) dysfunction is common after heart transplantation, and myocardial ischemia is considered to be a significant contributor. We studied whether intraaortic balloon counterpulsation would improve cardiac function using a model of acute RV pressure overload. METHODS In 10 anesthetized sheep, RV failure was induced using a pulmonary artery constrictor. Baseline measurements included mean systemic blood pressure, RV peak systolic pressure, cardiac index, and RV ejection fraction. Myocardial and organ perfusion were measured using radioactive microspheres. RESULTS After pulmonary artery constriction, there was an increase in RV peak systolic pressure (32 +/- 2 to 60 +/- 3 mm Hg; p < 0.01) and a decrease in mean systemic blood pressure (68 +/- 4 to 49 +/- 2 mm Hg; p < 0.01), RV ejection fraction (0.51 +/- 0.04 to 0.16 +/- 0.02; p < 0.01), and cardiac index (2.48 +/- 0.04 to 1.02 +/- 0.11; p < 0.01). Blood flow to the RV did not change significantly, but there was a significant reduction in blood flow to the left ventricle. The initiation of intraaortic balloon counterpulsation (1:1) using a 40-mL intraaortic balloon inserted through the left femoral artery resulted in an increase in mean systemic blood pressure (49 +/- 2 to 61 +/- 3 mm Hg; p < 0.01), cardiac index (1.02 +/- 0.11 to 1.45 +/- 0.14; p < 0.05), RV ejection fraction (0.16 +/- 0.02 to 0.23 +/- 0.02; p < 0.01), and blood flow to the left ventricle. CONCLUSIONS In a model of right heart failure, the institution of intraaortic balloon counterpulsation caused a significant improvement in cardiac function. Although RV ischemia was not demonstrated, the augmentation of left coronary artery blood flow by intraaortic balloon counterpulsation and subsequent improvement in left ventricular function suggest that left ventricular ischemia contributes to RV dysfunction, presumably through a ventricular interdependence mechanism. Therefore, study of the safety and efficacy of intraaortic balloon counterpulsation in the management of patients with acute right heart dysfunction is warranted.

Frusemide administration in critically ill patients by continuous compared to bolus therapy.

Background: Frusemide is frequently administered to critically ill patients in the intensive care unit (ICU). We investigated whether continuous frusemide infusion therapy was more effective than regular intermittent bolus doses at causing diuresis. Methods: 59 adult patients with fluid overload admitted to two tertiary multidisciplinary ICUs were randomised to either a continuous frusemide infusion or regular intermittent intravenous boluses of frusemide according to pre-defined algorithms aiming for a minimum hourly urine output. Results: There was no significant difference in diuretic response between the two groups during the first 24 h (5.3 liters in the bolus group vs. 5.4 liters in the infusion group). In the bolus group a significantly higher dose of frusemide was needed to achieve target diuresis (24.1 vs. 9.2 mg/h in the infusion group, p = 0.0002). Mean urine output per dose of frusemide was significantly higher in the infusion group (31.6 vs. 18 ml/mg in the bolus group, p = 0.014). At the end of the study, there were no differences in hospital mortality, number of patients requiring ventilatory support, change in serum creatinine or change in estimated glomerular filtration rate. Conclusions: Both intermittent boluses and continuous infusion of frusemide were successful in achieving algorithm-driven diuresis. However, continuous infusion therapy was more effective than intermittent boluses since the dose of frusemide required was significantly less.

Acute paralysis following "a bad potato": a case of botulism.

PurposeIntensivists often encounter patients with respiratory failure as a result of neuromuscular disease, however, acute neuromuscular syndromes are less common. We present a case of food borne Clostridium botulism and discuss the diagnostic and therapeutic considerations.Clinical findingsA 35-yr-old healthy male presented with abdominal pain and blurred vision 12 hr after ingesting a “bad“ potato. During the next 17 hr, the patient demonstrated a gradual descending paralysis which ultimately resulted in no cranial nerve function and 0/5 strength in all extremities. Sensation was intact. The patient required intubation and mechanical ventilation. His blood count, biochemical profile, computerized tomography and magnetic resonance imaging of the head were normal. A lumbar puncture revealed no abnormalities. Due to the rapid deterioration and presentation of ’descending’ paralysis, botulism was suspected. The patient was treated empirically with botulinum anti-toxin. Samples of blood, stool and gastric contents were cultured for the presence of Clostridium botulinum and its toxin and these tests were positive for botulinum toxin A 12 days later. The patient’s neuromuscular function gradually improved over a prolonged period of time. Six and one-half months after his initial presentation, the patient was discharged home after completing an aggressive rehabilitation program.ConclusionsBotulism is a rare syndrome and presents as an acute, afebrile, descending paralysis beginning with the cranial nerves. If suspected, botulinum anti-toxin should be considered, particularly within the first 24 hr of onset of symptoms. Confirmation of the presence of botulinum requires days therefore the diagnosis and management rely on history and physical examination.RésuméObjectifBeaucoup de patients présentent une insuffisance respiratoire causée par une affection neuromusculaire, les syndromes neuromusculaires aigus étant plus rares. Nous présentons un cas d’intoxication alimentaire à Clostridium botulinum et discutons du diagnostic et du traitement.AbstractÉléments cliniquesUn homme sain de 35 ans a consulté pour des douleurs abdominales et une vision floue 12 h après avoir mangé une «mauvaise patate». Pendant les 17 h suivantes, une paralysie descendante graduelle s’est installée et a finalement provoqué la perte de fonction des nerfs crâniens et réduit à 0/5 la force des extrémités. La sensation était intacte. Il a fallu intuber et ventiler le patient. La numération plaquettaire, le profil biochimique, la tomographie par ordinateur et l’imagerie par résonance magnétique de la tête étaient normaux. Une ponction lombaire n’a révélé aucune anomalie. Devant la détérioration rapide et la paralysie «descendante», nous avons pensé au botulisme. Un traitement empirique avec une antitoxine botulinique a été administré. Les échantillons de sang, de selles et du contenu gastrique ont été mis en culture pour vérifier la présence du Clostridium botulinum. La présence de la toxine botulinique type A a été révélée 12 jours plus tard. La fonction neuromusculaire s’est graduellement améliorée sur une longue période. Six mois et demi après sa première visite, le patient a pu partir après un programme de réadaptation complet et énergique.ConclusionSyndrome rare, le botulisme se présente comme une paralysie aiguë, afébrile et descendante affectant d’abord les nerfs crâniens. S’il est soupçonné, il faut penser à l’antitoxine botulinique, surtout au cours des 24 premières heures de l’apparition des symptômes. La confirmation de la présence de Clostridium botulinum demandant des jours, le diagnostic et le traitement reposent sur l’histoire et l’examen physique.

The apnea test for brain death determination: an alternative approach.

AbstractIntroduction: Problems associated with the standard apnea test relate to overshooting or undershooting the target PaCO2, potentially compromising the viability of organs for transplantation or invalidating the test. Materials and Methods: In 60 adult patients, the authors used an alternative method using exogenously administered CO2 and measurement of end-tidal CO2. Results: All patients achieved an adequate respiratory stimulus (mean increase in PaCO2 was 28±3 mmHg, postapnea test pH was 7.20±.02). There was a clinically insignificant reduction in arterial blood pressure during testing, but no other complications occurred. Multiple regression analysis demonstrated a correlation between the predicted PaCO2 (predicted from the end-tidal CO2) and measured PaCO2 (64±9 versus 67±9; r=.75169, p<0.0001). Conclusion: Exogenously administered CO2 as an alternative method for the standard apnea test was a reliable and safe method, with minimal complications that offers several advantages over the standard method.

Five-year experience with donation after cardiac death kidney transplantation in a Canadian transplant program: Factors affecting outcomes.

BACKGROUND : Donation after cardiac death (DCD) has led to an increase of up to 40% in the number of kidney transplants in some programs. Unfortunately, the increase in warm ischemic time results in higher rates of delayed graft function (DGF). The purpose of our study was to examine our initial 5-year experience with DCD kidney transplantation and to determine the factors involved in early postoperative function and function at 1 year. METHODS : This retrospective study included a review of the recipient and donor charts of 63 DCD kidneys retrieved and transplanted by the London Multi-Organ Transplant Program between July 2006 and October 2011. Comparisons were carried out between our early (n=31, July 2006 to January 2009) and our recent experience (n=32, March 2009 to October 2011). DGF and creatinine clearance at 3, 7 and 365 days were examined with regression analyses. RESULTS : DGF was seen in 65% of transplanted kidneys. Mean creatinine clearance (CrCl) at 1 year was 66.7 mL/min. Low pre-transplant recipient daily urine output was the most statistically significant predictor of DGF in multivariate analysis (p < 0.001). In comparisons between our early and more recent results, improvements were noted in time from asystole to flush (16.0 vs. 12.0 minutes, p = 0.003), while cold ischemic time increased (464 vs. 725 minutes, p = 0.006). Experience contributed to a significant reduction in hospital length of stay (16 vs. 13 days, p = 0.035) and improved early renal function (CrCl at 3 days 7.8 vs. 11.9 mL/min, p = 0.027). The use of machine cold perfusion and higher recipient preoperative daily urine output predicted improved early renal function, while increasing donor age predicted poorer function at 1 year. DISCUSSION : Despite early DGF, our results justify the continued transplantation of kidneys from DCD donors.