Sundar Krishnan

Community based trials and informed consent in rural north India

Disease control has increasingly shifted towards large scale, disease specific, public health interventions. The emerging problems of HIV, hepatitis, malaria, typhoid, tuberculosis, childhood pneumonia, and meningitis have made community based trials of interventions a cost effective long term investment for the health of a population. The authors conducted this study to explore the complexities involved in obtaining informed consent to participation in rural north India, and how people there make decisions related to participation in clinical research.

Acute Right Ventricular Dysfunction: Real-Time Management With Echocardiography

In critically ill patients, the right ventricle is susceptible to dysfunction due to increased afterload, decreased contractility, or alterations in preload. With the increased use of point-of-care ultrasonography and a decline in the use of pulmonary artery catheters, echocardiography can be the ideal tool for evaluation and to guide hemodynamic and respiratory therapy. We review the epidemiology of right ventricular failure in critically ill patients; echocardiographic parameters for evaluating the right ventricle; and the impact of mechanical ventilation, fluid therapy, and vasoactive infusions on the right ventricle. Finally, we summarize the principles of management in the context of right ventricular dysfunction and provide recommendations for echocardiography-guided management.

Efficacy of an online education program for ultrasound diagnosis of pneumothorax

Background:Experienced ultrasonographers can rule out pneumothorax reliably. The authors hypothesized that with basic training, anesthesia residents and faculty can also reliably rule out pneumothorax when presented with an optimal ultrasound image of the chest. Methods:The study investigators created a library of 99 ultrasound video images of the chest with or without pneumothorax obtained from 53 patients undergoing elective thoracic surgery. After a 5-min tutorial, the physicians were invited to take a quiz based on 20 ultrasound videos randomly selected from the library. Sensitivity and specificity were calculated for overall performance, and a generalized estimating equations model was created to identify significant independent covariates affecting performance. To detect the retention rate for this skill, participants were asked to take the quiz again 6 months later. Results:Seventy-nine anesthesia residents and faculty took part in the study. The sensitivity and specificity for ruling out pneumothorax was 86.6% and 85.6% respectively. On generalized estimating equation model, participants were significantly less likely to identify ultrasound features of pneumothorax if there was probe movement (P value = 0.002; OR 2.69; 95% CI 1.61–4.5) or heartbeat (P < 0.001; OR 3.54; 95% CI 2.27–5.51) on the ultrasound video. The median and interquartile ranges for scores (90%, and 80–95% respectively) did not change from the first to the second quiz. Conclusion:After viewing a 5-min online training video, physicians can reliably rule out pneumothorax on an optimal ultrasound image. They are also able to retain this skill for up to 6 months.

Implementing a hybrid web-based curriculum for an elective medical student clerkship in a busy surgical intensive care unit (ICU): effect on test and satisfaction scores.

OBJECTIVE To determine whether a hybrid traditional and web-based curriculum improves test scores and enrollment among senior medical students in an elective critical care rotation. DESIGN AND SETTING Retrospective study in a surgical ICU at a major academic center. SUBJECTS One hundred twenty-one fourth year medical students completing an elective ICU clerkship between 2007 and 2010. INTERVENTIONS Pre-test and post-test during a 4-week rotation. METHODS We implemented a hybrid curriculum that involved both traditional teaching methods and a new online core curriculum that incorporating audio, video, and text using screen capture technology. The curriculum was hosted on a secure online portal called ICON (Desire2Learn Inc., Ontario, Canada). The core curriculum covered topics that were considered essential to meet the didactic objectives of the rotation. MEASUREMENTS AND EVALUATIONS: A pre-test was administered online on day 1 of the rotation. A post-test was administered on the second to last day of the rotation. Both tests were composed of 20 questions randomly chosen from a question bank of 100 questions. The tests are managed (administering, grading, and reporting) exclusively online. RESULTS One hundred twenty-one medical students have successfully completed the clerkship since implementing the new curriculum. Each group of students showed an improvement in the mean post-test score by at least 17%+ to 10%. The satisfaction scores of the clerkship improved consistently from 2007 and is currently rated at 4.31 ± 0.85 (on a 5-point scale). The rotation is in the top 25(th) percentile of all clinical clerkships offered at the University of Iowa. CONCLUSION A systematically implemented hybrid web-based critical care curriculum can improve knowledge based test scores and overall clerkship satisfaction scores in a busy surgical ICU.

Identification of coronary sinus injury by transesophageal echocardiography during placement of a retrograde cardioplegia catheter for minimally invasive cardiac surgery.

March 2013 • Volume 116 • Number 3 A 70-year-old man presented with chest pain and progressive shortness of breath. Written consent for publication of this case has been obtained from the patient. His medical history was significant for coronary artery bypass grafting through a full sternotomy 16 years previously. Transthoracic echocardiography showed a severely calcified aortic valve (AV) with moderate to severe aortic stenosis, mild aortic regurgitation, mild concentric left ventricular hypertrophy, and left ventricular ejection fraction of 55% to 60%. He was scheduled for AV replacement via a reoperative upper hemisternotomy. After induction of anesthesia, transesophageal echocardiography (TEE) confirmed severe aortic stenosis. We then attempted to place a coronary sinus (CS) catheter (EndoplegeTM sinus catheter, Edwards Lifesciences LLC, Irvine, CA) through the right internal jugular vein via an 11 Fr introducer sheath. The CS was visualized in the modified midesophageal 4-chamber view and the modified midesophageal bicaval view. After multiple attempts, the catheter was successfully engaged just beyond the ostium of the CS with the aid of echocardiography. There was some difficulty in advancing the catheter further into the CS. Venous angiogram under fluoroscopy, using manual injection of 6 to 8 mL of contrast diluted 1:1 with saline, was performed to determine vascular anatomy. Fluoroscopy confirmed catheter tip engagement in the CS ostium; however, it also suggested extravasation of contrast (Fig. 1 and Video 1, see Supplemental Digital Content 1, http://links.lww.com/AA/A506). On TEE, air and fluid were noticed in the pericardial space in the posterior left atrioventricular groove (Fig. 2 and Video 2, see Supplemental Digital Content 2, http://links.lww.com/ AA/A507), along with a small generalized pericardial effusion (Video 3, see Supplemental Digital Content 3, http:// links.lww.com/AA/A508) without signs of tamponade. Close to the CS ostium a bifurcation was noticed in the CS, which was possibly the junction of the middle cardiac vein into the CS (Video 3, http://links.lww.com/AA/A508). This combination of radiographic and echocardiographic signs suggested possible injury to the CS. The CS catheter was consequently removed. Since the patient was hemodynamically stable at this point, the surgical procedure was abandoned to allow the CS time to heal. The patient was admitted to the intensive care unit for overnight observation. Continuous invasive hemodynamic monitoring and Identification of Coronary Sinus Injury by Transesophageal Echocardiography During Placement of a Retrograde Cardioplegia Catheter for Minimally Invasive Cardiac Surgery

Unilateral pulmonary venous occlusion caused by a localized pericardial clot

On postoperative day 1 after bioprosthetic aortic valve replacement and coronary artery bypass grafting, a 53-year-old man suffered cardiac arrest requiring chest compressions. This was followed by an increase in oxygen requirement. Chest X-ray revealed early signs of unilateral pulmonary edema (Fig. 1a). On transesophageal echocardiography (TEE) a clot was visualized in the transverse sinus, with lateral and posterior extension of the clot causing compression of the left atrial appendage (LAA). Turbulent flow was noticed in the left upper pulmonary vein (LUPV) on color Doppler, with peak velocities of 160 cm/s on pulse wave Doppler (Fig. 1b). On mediastinal exploration, approximately 15 ml of clot was found around the left pulmonary veins, behind the LAA, and adherent to the distal anastomosis on the ramus intermedius. After clot removal, the LUPV and the LAA were more clearly visualized, and the clot burden in the transverse sinus was significantly reduced. Blood flow in the LUPV was laminar, with a peak velocity of 90 cm/s (Fig. 1c). A localized pericardial clot causing pulmonary venous compression can lead to unilateral pulmonary edema. Unilateral pulmonary edema can also occur as a result of

ECMO Weaning and Decannulation

As pulmonary function recovers in ARDS patients on ECMO, pulmonary mechanics and gas exchange improve. Depending on the mode of extracorporeal support (venovenous versus venoarterial), oxygenator sweep gas flow or ECMO pump blood flow is slowly weaned. Once stability at low levels of support is established, patients are trialed-off from ECMO for 1–2 h to prove that cardiopulmonary function can be maintained at reasonable levels of support by conventional methods. ECMO support is then terminated and the cannulae are removed. Unfortunately, in some other patients, further therapy might be deemed to be futile, and therapy would have to be terminated. Goals for ECMO weaning and decannulation should ideally be set before extracorporeal support is initiated.

The chicken or the egg: Hypertension secondary to intraoperative subarachnoid hemorrhage

To JNA Readers: Perioperative hypertension, particularly during emergence from anesthesia, has been implicated as a risk factor for intracranial bleeding. However, subarachnoid hemorrhage (SAH) can also lead to systemic hypertension due to overactivation of the sympathetic nervous system.2 A common dilemma encountered when neurosurgical patients rebleed perioperatively is whether hypertension is the result of rebleeding or its cause. Knowing which came first has both medical and medicolegal consequences. Although intracranial hemorrhageinduced hypertension is a well-known fact among neuroanesthesiologists, there has been no previous documentation of this phenomenon. We report a case where the availability of carefully timed radiologic imaging and electronically recorded blood pressures clearly indicated that recurrent SAH preceded the hemodynamic changes by about 2 minutes. A 58-year-old woman presented with a World Federation of Neurologic Surgeons grade I SAH. Cerebral angiography performed under general anesthesia revealed a wide-neck 3.8mm diameter aneurysm arising from the right anterior communicating artery, for which the neuroradiologist proceeded to perform stent-assisted coiling. An initial angiogram performed at 3:56 PM demonstrated the location of the aneurysm (Fig. 1A). At 4:05 PM, during deployment of the second coil in the aneurysm, abrupt extravasation of contrast was noticed, indicating aneurysmal rerupture (Fig. 1B, with circle around the contrast extravasation). The accompanying anesthesia record obtained through the Epic Anesthesia Information Management System demonstrated a stable hemodynamic profile before aneurysmal rerupture, and hypertension was noticed 2 minutes after aneurysmal rerupture (Fig. 1C, with arrow marking the time for Fig. 1B) despite a stable anesthetic depth. Blood pressure was subsequently normalized with intravenous antihypertensives. The aneurysm was additionally coiled, with a repeat angiogram showing the complete occlusion, with no further extravascular leak. In 1988, Kalfas and Little3 reported an incidence of new postoperative hematomas in 2.1% of patients undergoing open aneurysm clipping. They argued that systemic hypertension caused intracranial hemorrhage at the operative site by disrupting operative hemostasis, disrupting autoregulation, and damaging the blood-brain barrier. They also observed that the absence of more detailed blood pressure recordings (in the era of paper anesthesia records) made it difficult to accurately evaluate this relationship. In contrast, SAH is known to cause an overactivation of the sympathetic nervous system with a >3-fold increase in the level of plasma norepinephrine, resulting in hypertension and tachycardia. This catecholamine storm can cause arrhythmias and neurogenic cardiomyopathy. The severity of SAH has been shown to be a strong, independent predictor of myocardial necrosis and cardiac dysfunction after SAH. In addition, markers of cardiac dysfunction are associated with an increased risk of worse outcomes after SAH.5 Although this single case cannot resolve the broader issue of cause and effect, we believe that a causal relationship is demonstrated in these images between intracranial hemorrhage and the resultant systemic hypertension.