J. X. Thomas

Selection Criteria for Residency: Results of a National Program Directors Survey

Purpose To assess the relative importance of criteria used for residency selection in 21 medical specialties given current available data and competitiveness of specialties. Method In 2006, questionnaires were distributed to 2,528 program directors in university hospital or university-affiliated community hospital residency programs across 21 medical specialties. Responses were recorded using a five-point Likert scale of importance. Mean values for each item were calculated within and across all specialties. Mean scores for item responses were used to create rank orders of selection criteria within the specialties. To facilitate comparisons, specialties were grouped according to the percentages of positions filled with U.S. medical school graduates. Results The overall response rate was 49%. With the data from all specialties pooled, the top five selection criteria were (1) grades in required clerkships, (2) United States Medical Licensing Examination (USMLE) Step 1 score, (3) grades in senior electives in specialty, (4) number of honors grades, and (5) USMLE Step 2 Clinical Knowledge (CK) score. Conclusions The top academic selection criteria are based on clinical performance, with the exception of USMLE Step 1 score. Indicators that reflect excellence in clinical performance are valued across the specialties by residency program directors regardless of competitiveness within the specialty. USMLE Step 2 CK ranks higher in the less competitive specialties, whereas research experience is more prominent in the most competitive specialties. The Medical Student Performance Evaluation was ranked lowest of all criteria by the program directors.

The Hemodynamic Effects of Treatment with Interleukin-2 and Lymphokine-Activated Killer Cells

STUDY OBJECTIVE To determine the hemodynamic alterations occurring during therapy with the maximally tolerated doses of interleukin-2 and lymphokine-activated killer cells. DESIGN Case series. SETTING Referal-based inpatient oncology service at a university medical center. PATIENTS A sequential sample of 13 patients with metastatic colon carcinoma, malignant melanoma, or hypernephroma who were receiving treatment with interleukin-2 and lymphokine-activated killer cells in the maximally tolerated doses. MEASUREMENTS AND MAIN RESULTS Pretreatment variables of mean arterial pressure, systemic vascular resistance, heart rate, pulmonary capillary wedge pressure, and cardiac index were compared with the same variables measured either immediately before the eighth dose of interleukin-2 or immediately before the initiation of pressor support with dopamine hydrochloride. When these values were compared with the pretreatment values, patients showed a significant decrease in mean arterial pressure (92 mm Hg compared with 75 mm Hg; P less than 0.0001), and systemic vascular resistance (15.1 compared with 8.5 mm Hg/L . min; P less than 0.0001), but an increase in heart rate (73 compared with 110 beats/min; P less than 0.0001) and cardiac index (3.1 compared with 4.7 L/min . m2 body surface area; P less than 0.0001). No significant change was noted in pulmonary capillary wedge pressure. Low systemic vascular resistance persisted throughout interleukin-2 therapy. Although blood pressure normalized in 24 hours, the systemic vascular resistance remained below baseline levels 6 days after interluekin therapy had been stopped. INTERVENTIONS Blood pressure was successfully supported at greater than 90 mm Hg with dopamine hydrochloride or phenylephrine hydrochloride, or both. CONCLUSIONS Therapy with high doses of interleukin-2 induces hemodynamic changes consistent with a high-output and low-resistance state similar to changes noted during the early phase of septic shock.

One hour of myocardial ischemia in conscious dogs increases β-adrenergic receptors, but decreases adenylate cyclase activity

An increased myocardial beta-adrenergic receptor density has been reported following myocardial ischemia. However, it is not clear whether these receptors are effectively coupled to adenylate cyclase which would be necessary for enhanced physiological responsiveness. We, therefore, examined the effects of myocardial ischemia in six conscious dogs (4 intact and 2 with posterior wall denervation) in which the left circumflex coronary artery was occluded. Ischemia was verified by measurement of regional blood flow by radioactive microspheres. After 1 h of coronary artery occlusion, the dogs were anesthetized with pentobarbital and the left ventricle was divided into normal, intermediate and ischemic regions. A crude membrane fraction was prepared from each region. beta-Adrenergic receptors were quantitated with 125I-cyanopindolol binding and adenylate cyclase activity was measured. In all six animals studied, beta-adrenergic receptor density increased progressively and adenylate cyclase activity decreased progressively, when the ischemic myocardium was compared to the intermediate and the non-ischemic myocardium. Since adenylate cyclase activity declined, these results do not support the concept that the increased beta-receptor density induced by myocardial ischemia is causally related to enhanced beta-adrenergic sensitivity.

Effects of interleukin 2 on cardiac function in the isolated rat heart.

Adoptive immunotherapy with IL 2 is associated with severe cardiovascular toxicities including peripheral and pulmonary edema, hypotension decreased systemic vascular resistance, increased heart rate, and an increased cardiac index. The purpose of this investigation was to determine whether IL 2 alone or in combination with lymphokine-activated killer cells (LAK) cells depress cardiac function using the isolated, perfused, working rat heart preparation. Male Sprague-Dawley rats (250-350 g) were anesthetized and the hearts were removed and placed on the perfusion apparatus. Hearts were perfused with oxygenated Krebs-Henseleit buffer (KHB), or oxygenated KHB containing IL 2 alone, IL 2-Media (cell culture media supplemented with 1,500 U IL 2/ml), LYMPH (cell culture media from cultured mononuclear cells from healthy volunteers), or LAK (cell culture media from cultured lymphocytes harvested from patients receiving IL 2/LAK in the presence of 1,500 U/ml IL 2). The cells were removed before perfusion (n = 9). Cardiac output and coronary flow were measured at 20-min intervals with preload constant (afterload varied or afterload constant (preload varied). The results indicate a significant depression in cardiac function in hearts treated with LAK. This depression was evident at 20 min and was more pronounced at 60 min. Washout of the KHB plus LAK reversed this depression. Thus, IL 2-stimulated/cultured human mononuclear cells produce a soluble factor that produces a reversible severe depression of cardiac function.

Relative roles of cardiac receptors and arterial baroreceptors during hemorrhage in conscious dogs.

To determine the relative roles of cardiac receptors and arterial baroreceptors during blood loss, the effects of acute hemorrhage on measurements of mean arterial pressure, cardiac output, stroke volume, total peripheral resistance, and heart rate were examined in chronically instrumented, conscious dogs with all nerves intact (n = 15) and following either cardiac denervation (CD, n = 14), sinoaortic denervation alone (SAD, n = 11), or combined sinoaortic denervation plus cardiac denervation (SAD + CD, n = 8). Hemorrhage at a constant rate (0.5 ml/kg/min) was continued until mean arterial pressure fell to 40 mm Hg or 30 ml/kg of blood was withdrawn. Hemorrhage (20 ml/kg) decreased mean arterial pressure similarly in the intact group (-15 +/- 3.3 mm Hg) and CD group (-17 +/- 3.2 mm Hg), but to a greater extent in the SAD (-53 +/- 3.4 mm Hg) and SAD + CD (-49 +/- 2.9 mm Hg) groups. Total peripheral resistance increased similarly in the intact (20.4 +/- 3.0 mm Hg/l/min) and CD (22.4 +/- 2.4 mm Hg/l/min) groups, but did not increase in SAD and SAD + CD groups. Acute cardiac denervation induced with intrapericardial lidocaine in either the intact or SAD groups resulted in similar responses of mean arterial pressure to hemorrhage as those observed in the chronic CD and chronic SAD + CD groups, respectively. Thus, dogs with cardiac denervation withstand hemorrhage and increase total peripheral resistance to a similar extent as intact dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adverse effects of chronic cardiac denervation in conscious dogs with myocardial ischemia.

The extent to which total chronic cardiac denervation protects the ischemic myocardium was investigated in conscious dogs. The major hemodynamic difference after coronary artery occlusion was that left ventricular end-diastolic pressure rose significantly more, P less than 0.01, in the denervated group (12 +/- 1.5 mm Hg) than in the normal group (4.4 +/- 1.4 mm Hg). Blood flow (radioactive microspheres) in the ischemic endo- and epicardium fell to similar levels at 3-5 minutes after coronary occlusion, but was significantly less (P less than 0.01) in denervated dogs at 3 hours after occlusion in the endo- (0.05 +/- 0.01) and epicardium (0.30 +/- 0.02 ml/min per g), than in the endo- (0.13 +/- 0.03) and epicardium (0.42 +/- 0.05 ml/min per g) in the normal group. A subgroup of normal dogs was also studied, with left ventricular end-diastolic pressure increased by volume loading to levels similar to those observed in the denervated group after coronary occlusion; in these dogs, blood flow was similar to that in the other two groups 3-5 minutes after coronary artery occlusion, but, at 3 hours, was significantly more depressed (P less than 0.01) than that observed in normal dogs without volume loading in both endo- (0.03 +/- 0.01) and epicardial (0.25 +/- 0.03 ml/min per g) layers. Infarct size, as a fraction of the area at risk, was significantly greater (P less than 0.05) in the denervated group (60 +/- 4.3%) and in the subgroup of normal dogs with elevated left ventricular end-diastolic pressure (73 +/- 5.8%), compared with the normal group without volume loading (37 +/- 8.1%). Thus, in conscious dogs, total chronic cardiac denervation exerts an adverse effect on infarct size which may be related to the sustained elevation in left ventricular end-diastolic pressure and consequent impairment of collateral perfusion.

Bifurcations and Intrinsic Chaotic and 1/f Dynamics in an Isolated Perfused Rat Heart

The application of the theory of chaotic dynamical systems has gradually evolved from computer simulations to assessment of erratic behavior of physical, chemical, and biological systems. Whereas physical and chemical systems lend themselves to fairly good experimental control, biologic systems, because of their inherent complexity, are limited in this respect. This has not, however, prevented a number of investigators from attempting to understand many biologic periodicities. This has been especially true regarding cardiac dynamics: the spontaneous beating of coupled and non-coupled cardiac pacemakers provides a convenient comparison to the dynamics of oscillating systems of the physical sciences. One potentially important hypothesis regarding cardiac dynamics put forth by Goldberger and colleagues, is that normal heart beat fluctuations are chaotic, and are characterized by a 1/f-like power spectrum. To evaluate these conjectures, we studied the heart beat intervals (R wave toR wave of the electocardiogram) of isolated, perfused rat hearts and their response to a variety of external perturbations. The results indicate bifurcations between complex patterns, states with positive dynamical entropies, and low values of fractal dimensions frequently seen in physical, chemical and cellular systems, as well as power law scaling of the spectrum. Additionally, these dynamics can be modeled by a simple, discrete map, which has been used to describe the dynamics of the Belousov-Zhabotinsky reaction.

Intracellular recordings from canine intracardiac ganglion cells

Stable transmembrane potentials were recorded from 60 canine intracardiac ganglion cells taken from 10 dogs, which had intact synaptic connections: mean resting membrane potential, input resistance and time constant were 61.5 mV, 70 M omega and 3.3 ms. Action potentials could be evoked by intrasomal current injection and by orthodromic and antidromic stimulation of interganglionic nerves. Orthodromic action potentials were initiated by excitatory postsynaptic potentials and mediated by nicotinic receptors. All action potentials could be blocked by tetrodotoxin. Intracellular labeling revealed large cell bodies and long dendritic and axonal processes. Thus, the functional and anatomical properties of canine cardiac ganglion cells and their synaptic connections can be elucidated using this preparation.

Transcutaneous electrical nerve stimulation does not augment combined spinal epidural labour analgesia.

PurposeThe spinal portion of the combined spinal epidural technique (CSE) provides dramatic but limited labour analgesia. Transcutaneous Electrical Nerve Stimulation (TENS) has been noted to modulate pain,1 in part by the frequency of stimulation chosen.2 Because nerve action potentials are blocked by local anesthestics in a frequency dependent manner,3 we speculated that a TENS unit could increase the quality and duration of the spinal portion of a CSE.MethodsForty parturients in active spontaneous labour, with a singleton, vertex, term fetus, requesting analgesia were enrolled in a randomized, double blind fashion to receive a standardized CSE with either an active or inactive TENS unit. Prior to CSE placement, TENS intensity thresholds were determined with electrodes placed on the paraspinus muscles at T10−L1, and S2–4; TENS settings for mode, cycle, and pulse width were standardized. Data were collected at timed intervals on pain (VAS), sensory level (pinprick), motor blockade (Bromage), cervical dilatation, and duration of analgesia, and at delivery on fetal and neonatal outcome.ResultsThe duration of the spinal portion ofthe CSE did not differ between groups (TENS off 91.1 ±33 [mean ± SD]vs TENS on 83.1 ± 28 min, P=.42). Kaplan-Meier survival analysis and Mantel-Cox log rank analysis showed no difference between the two treatments (P=.28). Analgesia was comparable throughout the first hour of spinal analgesia.ConclusionIn healthy labouring parturients, the application of a TENS unit did not alter the quality or duration of labour analgesia provided by the spinal portion of CSE analgesia.RésuméObjectifrLa composante rachidienne de la technique rachidienne péridurale combinée (RPC) fournit une analgésie importante, mais limitée, pendant le travail obstétrical. La neurostimulation transcutanée (NST) est connue pour moduler la douleur1, entre autres selon la fréquence de stimulation choisie.2 Comme les potentiels d’action nerveuse sont bloqués par les anesthésiques locaux d’une manière qui dépend de la fréquence,3 nous avons pensé qu’une unité de NST pourrait augmenter la qualité et la durée de la composante rachidienne de l’analgésie RPC.MéthodeQuarante parturientes en travail actif spontané, porteuses d’un fœtus unique, à terme et en présentation du sommet, ont été réparties au hasard et à double insu. Elles ont reçu une analgésie RPC standard avec une unité active ou inactive de NST. Avant la mise en place de l’analgésie RPC, l’intensité des seuils de NST a été déterminée avec des électrodes placées sur les muscles paravertébraux à T10 −L1, et S2–4 ; l’installation de la NST a été standardisée quant au mode, au cycle et la durée du stimulus. On a recueilli, à intervalles déterminés, des données sur la douleur (EVA), le niveau sensitif (piqûre), le blocage moteur (Bromage), la dilatation cervicale et la durée de l’analgésie et, à la naissance, sur l’évolution fœtale et néonatale.RésultatsIl n’y a pas eu de différence intergroupe pour la durée de la composante rachidienne de l’analgésie RPC (NST inactive 91, 1 ±33 [moyenne ± écart type]vs NST active 83,1 ± 28 min,P = 0,42). L’analyse de survie de Kaplan-Meier et l’analyse du logrank de Mantel-Cox n’ont montré aucune différence entre les deux façons de procéder (P = 0,28). L’analgésie a été comparable pendant la première heure d’analgésie rachidienne.ConclusionChez des parturientes en santé, l’application de NST n’a pas changé la qualité et la durée de l’analgésie pendant le travail fournie par la portion rachidienne d’une analgésie RPC.

Teaching pediatrics residents how to obtain informed consent.

Background Few physicians view informed consent as a critical component of the physician–patient relationship or as a way to improve individual and population health. We hypothesized that formal education about informed consent would affect first-year pediatrics residents’ knowledge and attitudes. Method Twenty-seven first-year pediatrics residents participated in a randomized controlled trial with a wait-list control group. The one-hour interactive intervention consisted of a lecture, video, and small-group discussion. Outcomes were measured after randomization at baseline and after the intervention group received the intervention. Data were analyzed using multivariate analysis and between and within group t tests. Qualitative data were obtained after the wait-list control group’s exposure to the intervention. Results The quantitative analyses demonstrated that the intervention yielded statistically significant improvements in the measured outcomes. The qualitative analyses confirm the quantitative findings. Conclusion A formal session on informed consent in the pediatrics residency educational program positively affects residents’ knowledge and attitudes about informed consent.