May student examiners be reasonable substitute examiners for faculty in an undergraduate OSCE on medical emergencies?

OBJECTIVES: To compare the effect of student examiners (SE) to that of faculty examiners (FE) on examinee performance in an OSCE as well as on post-assessment evaluation in the area of emergency medicine management. METHODS: An OSCE test-format (seven stations: Advanced Cardiac Life Support (ACLS), Basic Life Support (BLS), Trauma-Management (TM), Pediatric-Emergencies (PE), Acute-Coronary-Syndrome (ACS), Airway-Management (AM), and Obstetrical-Emergencies (OE)) was administered to 207 medical students in their third year of training after they had received didactics in emergency medicine management. Participants were randomly assigned to one of the two simultaneously run tracks: either with SE (n = 110) or with FE (n = 98). Students were asked to rate each OSCE station and to provide their overall OSCE perception by means of a standardized questionnaire. The independent samples t-test was used and effect sizes were calculated (Cohens d). RESULTS: Students achieved significantly higher scores for the OSCE stations "TM", "AM", and "OE" as well as "overall OSCE score" in the SE track, whereas the station score for "PE" was significantly higher for students in the FE track. Mostly small effect sizes were reported. In the post-assessment evaluation portion of the study, students gave significant higher ratings for the ACS station and "overall OSCE evaluation" in the FE track; also with small effect sizes. CONCLUSION: It seems quite admissible and justified to encourage medical students to officiate as examiners in undergraduate emergency medicine OSCE formative testing, but not necessarily in summative assessment evaluations.

Choice of hospital after out-of-hospital cardiac arrest--a decision with far-reaching consequences: a study in a large German city.

INTRODUCTION: Between 1 and 31% of patients suffering out-of-hospital cardiac arrest (OHCA) survive to discharge from hospital. International studies have shown that the level of care provided by the admitting hospital determines survival for patients suffering from OHCA. These data may only be partially transferable to the German medical system where responders are in-field emergency medical physicians. The present study determines the influence of the emergency physician's choice of admitting hospital on patient outcome after OHCA in a large urban setting. METHODS: All data for patients collected in the German Resuscitation Registry for the city of Dortmund during 2007 and 2008 were analyzed. Patients under 18 years of age, with traumatic mechanism, and with incomplete charts were excluded. Admitting hospitals were divided into two groups: those without the capability for percutaneous coronary intervention (PCI), and those with PCI capability. Data were analyzed by multivariate statistics, taking into account the effects of mild therapeutic hypothermia treatment and PCI capability of the admitting hospital with respect to the neurological status upon hospital discharge. RESULTS: Between 2007 and 2008 a total of 1,109 cardiopulmonary resuscitation attempts were registered for the city of Dortmund, of which 889 could be included in our study. Return of spontaneous circulation was achieved in 360 of 889 patients (40.5%). In total, 282 of 889 patients displayed return of spontaneous circulation during transport to the hospital (31.7%); 152 were transported with ongoing cardiopulmonary resuscitation (17.1%). Of the total 434 patients admitted to hospital, 264 were admitted to hospitals without PCI capability and 170 to hospitals with PCI capability. Multivariate analysis demonstrated a significant influence on patient discharge with good neurological status for those admitted to PCI hospitals (odds ratio 3.14 (95% confidence interval 1.51 to 6.56)), independent of receiving mild therapeutic hypothermia and/or PCI. Compared with patients admitted to hospitals without PCI capability, significantly more patients in PCI hospitals were discharged alive (41% vs. 13%, P < 0.001) and remained alive 1 year after the event (28% vs. 6%, P < 0.001). CONCLUSIONS: The choice of admitting hospital for patients suffering OHCA significantly influences treatment and outcome. This influence is independent of PCI performance and of mild therapeutic hypothermia. Further analysis is required to determine the possible parameters determining patient outcome.

Mid-term results of different aortic valve-sparing procedures in Marfan syndrome.

BACKGROUND AND AIM OF THE STUDY: Marfan patients with aortic root aneurysm are typically treated with the Bentall procedure, though aortic valve-sparing procedures (AVSPs) are also possible. The study aim was to compare the authors' experience with two such techniques performed at their institution, namely a reimplantation according to David (David I) and remodeling according to Yacoub. METHODS: Between 1996 and 2009, a total of 37 Marfan patients underwent an AVSP at the authors' institution. Of these patients, 25 (mean age 32 +/- 14.9 years) underwent surgery according to David (group D), and 12 (mean age 35 +/- 10.9 years) according to Yacoub (group Y). The patients underwent both clinical and echocardiographic follow up examinations at a mean of 42.0 +/- 36.4 months after surgery. RESULTS: One patient from each group had moved abroad and was lost to follow up. The remaining 35 patients were alive at follow up, and none presented with any major neurological or bleeding complications. In addition, no significant differences were noted between the groups in terms of NYHA classification, left ventricular function, or left ventricular diameter. At follow up, aortic valve function was also comparable between groups, with a peak/mean gradient of 9.4 +/- 6.4/5.3 +/- 3.5 mmHg and 5.1 +/- 3.3/2.8 +/- 1.5 mmHg for groups D and Y, respectively (p = 0.081/0.058). The measured mean grades of aortic valve regurgitation were comparable in groups D and Y (0.6 +/- 0.7 and 1.1 +/- 0.6, respectively; p = 0.055). However, aortic root dimensions obtained via M-mode were smaller in group D patients (29.6 +/- 2.3 mm) than in group Y patients (36.1 +/- 6.6 mm) (p = 0.027). Only three patients from group Y required reoperation on the aortic valve due to valvular regurgitation (p = 0.028); two of these had presented with aortic dissection at the first operation. CONCLUSION: Both types of AVSP can be performed with comparably good interim clinical results, and also low mortality and morbidity, in patients with Marfan syndrome.

[Fluid management - which fluid for what type of patients?]. / Perioperatives Flüssigkeitsmanagement - Welches Volumen für welchen Patienten?

There is a renewed discussion about the role of crystalloids and natural as well as synthetic colloids in fluid resuscitation. Based on the currently available evidence the choice of fluid replacement does not influence mortality. However, there is increasing evidence that due to unwarranted organ effects of the specific replacement fluids, individual subgroups of patients may be preferentially treated either with cristalloids or colloids.

Hypoproteinemia does not alter plasma volume expansion in response to a 0.9% saline bolus in awake sheep.

OBJECTIVE: To test the hypothesis that hypoproteinemia reduces plasma volume expansion produced by a bolus of crystalloid solution given to awake sheep. DESIGN: Prospective and observational. SETTING: Laboratory. SUBJECTS: Five female merino sheep (n = 5) weighing 37 ± 3 kg were anesthetized. INTERVENTIONS: Each animal was subjected to a 5-day test period: day 1: 50 mL/min 0.9% saline infusion over 20 mins. Days 2-4: daily plasmapheresis and replacement of the shed plasma with 6 L of 0.9% saline were performed in increments. MEASUREMENTS AND MAIN RESULTS: Fractional plasma volume expansion after rapid infusion of saline on days 1 and 5 was calculated from changes in hemoglobin concentration. There was a significant reduction in total plasma protein concentration after plasmapheresis (p < .05). Colloid osmotic pressures were also significantly lowered (p < .05). A crystalloid infusion of 0.9% saline did not alter any of these values compared with baseline. The hemodynamic measurements did not show significant differences between the experiments. The plasma volume expansion reached approximately 20% at the end of infusion and stayed at 10-15% during the experiments. No difference was found in plasma volume expansion produced by a bolus of 50 mL/min of 0.9% in the hypoproteinemic state when compared with the euproteinemic state (p = .61). No difference in cumulative urinary output was found between the two states. CONCLUSIONS: In contrast to our hypothesis, severe acute hypoproteinemia does not reduce plasma volume expansion in response to 50 mL/min 0.9% saline infusion in nonspleenectomized sheep when compared with the resultant plasma volume expansion after a 50 mL/min of 0.9% infusion in the euproteinemic state.

Can today's house officers teach effectively? An assessment in undergraduate emergency training.

BACKGROUND: Previous publications describe house officers (HOs) as unaware of their ineffective teaching skills. OBJECTIVE: The aim of this study was to evaluate the role of teaching seniority in the comparison of teaching skills between HOs and faculty. MATERIALS AND METHODS: Ten HOs (F: n=4, M: n=6, age: 35.1±6.8 years) and nine faculty (F: n=3, M: n=6, age: 41.4±4.9 years) who actively teach undergraduate emergency medicine were immediately evaluated at the end of the course by their students using the questionnaire SFDP26. The questionnaire consists of one item on 'overall teaching effectiveness' (OTE) (1=very poor to 5=excellent) and 25 items measured on a five-point Likert scale (1-5=strongly disagree to strongly agree) divided into seven subscales: 1, 'establishing the learning climate' (LC); 2, 'control of session' (CS); 3, 'communication of goals' (CG); 4, 'facilitating understanding and retention' (UR); 5, 'evaluation' (E); 6, 'feedback' (FB) and 7, 'promoting self-directed learning' (SL). The sample included 173 medical students in their third year of training who were randomly assigned to the instructors. A Mann-Whitney U-test was used to calculate group-related differences (resident vs. teaching faculty). For significant differences, effect size was calculated (r=Z/√N). RESULTS: No sex-related differences were found. Significantly better ratings for HOs were found in subscales: 1, 'LC' (P=0.001; r=0.20); 2, 'CS' (P=0.037; r=0.15); 5, 'E' (P=0.007; r=0.20); 6, 'FB' (P=0.001; r=0.23); 7, 'SL' (P=0.004; r=0.24) and 'OTE' (P=0.027; r=0.26). CONCLUSION: From a learner's perspective, the quality of teaching provided by HOs was rated at least similar and mostly better overall than that provided by faculty. These findings contradict results from previous studies on the quality of HO teaching and therefore warrant further assessment.

Low preoperative cerebral oxygen saturation is associated with longer time to extubation during fast-track cardiac anaesthesia.

OBJECTIVES: Fast-track cardiac anaesthesia programs aiming at early tracheal extubation have not only been linked to a decrease in intensive care unit and hospital length of stay but also to a decrease in morbidity and mortality as well as a containment of rising medical costs. General recommendations for the inclusion criteria concerning fast-track programs are not available. METHODS: The present study determined the factors influencing the time to extubation in patients undergoing a newly implemented fast-track protocol. Seventy-nine patients were retrospectively studied. Successful fast track was defined as time to extubation within 75 min after admission to ICU. RESULTS: Sixty patients fulfilled the successful fast-track criteria with a mean time to extubation of 43.9 min (range 15-75 min). Nineteen patients needed more than 75 min to be weaned from the respirator with a mean time to extubation of 135 min (range 90-320 min). Analysis of pre- and intraoperative factors revealed that these groups differed only with respect to preoperative cerebral oxygen saturation levels: 67.7 ± 5.2 versus 60.8 ± 7.4%. CONCLUSIONS: Cerebral oxygen saturation assessment prior to cardiac surgery is significantly related to time to extubation and may thus be used to stratify candidates in fast-track programs.

Sepsis produced by Pseudomonas bacteremia does not alter plasma volume expansion after 0.9% saline infusion in sheep.

Clinicians generally consider sepsis to be a state in which fluid is poorly retained within the vasculature and accumulates within the interstitium. We hypothesized that infusion of 0.9% saline in conscious, chronically instrumented sheep with hyperdynamic bacteremic sepsis would be associated with less plasma volume expansion (PVE) and greater interstitial fluid volume expansion than in conscious, nonseptic sheep. Six conscious adult sheep received an IV infusion of 25 mL/kg of 0.9% saline over 20 min (1.25 mL.kg(-1).min(-1)) in a control nonseptic state and during early and late sepsis (4 and 24 h, respectively, after initiation of a standard infusion of live Pseudomonas aeruginosa). The distribution and elimination of infused fluid were studied by mass balance (after measurement of plasma volume using Evans blue dye) and volume kinetic analysis. Mass balance demonstrated no significant differences in the time-course of PVE between control, early sepsis, and late sepsis. At the end of the infusions, which averaged 1050 +/- 125 mL in sheep weighing an average of 42 +/- 5 kg, calculated PVE was 312 +/- 50 mL, 386 +/- 34 mL, and 400 +/- 51, respectively. Volume kinetic analysis was similar in all three protocols. In both nonseptic and septic sheep, infusion of 0.9% saline resulted in similar peak PVE and resolution of PVE over a 3-h interval and similar kinetic parameters. Contrary to clinical impressions and to our hypothesis, the distribution of 0.9% saline in this animal model was not changed by bacteremia produced by infusion of Pseudomonas aeruginosa.

Volume turnover kinetics of fluid shifts after hemorrhage, fluid infusion, and the combination of hemorrhage and fluid infusion in sheep.

BACKGROUND: Hemorrhage is commonly treated with intravenous infusion of crystalloids. However, the dynamics of fluid shifts between body fluid spaces are not completely known, causing contradictory recommendations regarding timing and volume of fluid infusions. The authors have developed a turnover model that characterizes these fluid shifts. METHODS: Conscious, chronically instrumented sheep (n = 12) were randomly assigned to three protocol groups: infusion of 25 ml/kg of 0.9% saline over 20 min (infusion only), hemorrhage of 300 ml (7.8 +/- 1.1 ml/kg) over 5 min (hemorrhage only), and hemorrhage of 300 ml over 5 min followed by infusion as noted above (hemorrhage plus infusion). A two-compartment volume turnover kinetic model containing seven model parameters was fitted to data obtained by repeated sampling of hemoglobin concentration and urinary excretion. RESULTS: The volume turnover model successfully predicted fluid shifts. Mean baseline volumes of the central and tissue compartments were 1799 +/- 1276 ml and 7653 +/- 5478 ml, respectively. Immediate fluid infusion failed to prevent hemorrhage-induced depression of cardiac output and diuresis. The model suggested that volume recruitment to the central compartment after hemorrhage was primarily achieved by mechanisms other than volume equilibration between the two model compartments. CONCLUSION: Volume turnover kinetics is a promising tool for explaining fluid shifts between body compartments after perturbations such as hemorrhage and intravenous fluid infusions. The pronounced inhibition of renal output after hemorrhage prevailed regardless of fluid infusion and caused fluid retention, which expanded the tissue compartment.

Volume kinetic analysis of the distribution of 0.9% saline in conscious versus isoflurane-anesthetized sheep.

BACKGROUND: The distribution and elimination of 0.9% saline given by intravenous infusion has not been compared between the conscious state and during inhalational anesthesia. METHODS: Six adult sheep received an intravenous infusion of 25 ml/kg of 0.9% saline over 20 min in the conscious state and also during isoflurane anesthesia and mechanical ventilation. The distribution and elimination of infused fluid were studied by volume kinetics based on serial analysis of hemoglobin dilution in arterial blood and by mass balance that incorporated volume calculations derived from volume kinetic analysis and measurements of urinary volumes. RESULTS: The mass balance calculations indicated only minor differences in the time course of plasma volume expansion between the conscious and anesthetized states. However, isoflurane anesthesia markedly reduced urinary volume (median, 9 vs. 863 ml; P < 0.03). In conscious sheep, the central and peripheral volume expansion predicted by volume kinetics agreed well with the calculations based on mass balance. However, during isoflurane anesthesia and mechanical ventilation, calculation using volume kinetic analysis of the variable kr, an elimination factor that, in conscious humans and sheep, is closely related to urinary excretion, represented both urinary excretion and peripheral accumulation of fluid. This suggests that the previous assumption that kr approximates urinary excretion of infused fluid requires modification, i.e., kr simply reflects net fluid movement out of plasma. CONCLUSIONS: In both conscious and anesthetized, mechanically ventilated sheep, infusion of 0.9% saline resulted in minimal expansion of plasma volume over a 3-h interval. In conscious sheep, infused 0.9% saline was rapidly eliminated from the plasma volume by urinary excretion; in contrast, the combination of isoflurane anesthesia and mechanical ventilation reduced urinary excretion and promoted peripheral accumulation of fluid.

Elimination rate constant describing clearance of infused fluid from plasma is independent of large infusion volumes of 0.9% saline in sheep.

BACKGROUND: The purpose of this study was to determine the influence of varying large crystalloid infusion volumes, ranging from a volume that has been safely administered to volunteers to a volume that greatly exceeds a practical volume for studies in normovolemic humans, of rapidly infused 0.9% saline on the elimination rate constant in sheep. METHODS: Six sheep underwent three randomly ordered, 20 min, intravenous infusions of 0.9% saline in volumes of 25 ml/kg, 50 ml/kg and 100 ml/kg. Repeated measurements of arterial plasma dilution were analyzed using the volume kinetic approach to determine the apparent volumes of the central (V1) and peripheral (V2) body fluid spaces, the elimination rate constant (kr) describing clearance from the central fluid space and the rate constant (kt) for the diffusion of fluid between the central and the peripheral fluid spaces. The latter constant was split in to two constants, one describing flow out from the central fluid space and one describing flow into the central fluid space. Urinary output was measured in all sheep. RESULTS: kr was comparable at each infused volume (38.3 +/- 4.5, 32.2 +/- 4.2, and 36.7 +/- 7.0 ml/min, respectively, in the 25 ml/kg, 50 ml/kg, and 100 ml/kg protocols). However, for the largest infusion, other kinetic parameters were influenced by the magnitude of the infusion. V2 was significantly increased (P < 0.05) and the area under the dilution-time curve divided by the infused volume was 20% lower for the largest infusion (P < 0.03). Although urinary output increased as the infusion volume increased, only 59% of the administered volume had been excreted at 180 min after the 100 ml/kg infusion as compared with approximately 90% after the other two infusions (P < 0.01). CONCLUSIONS: Elimination from the central fluid space of large, rapidly infused volumes of saline solution is independent of infused volume. Larger volumes are apparently cleared from the central fluid space (V1) by expansion of a peripheral volume (V2) as renal excretion fails to increase in proportion to the volume of infused fluid.