Impact of Positive End-Expiratory Pressure on Thermodilution-Derived Right Ventricular Parameters in Mechanically Ventilated Critically Ill Patients.

OBJECTIVES: To examine the effect of positive end-expiratory pressure (PEEP) on right ventricular stroke volume variation (SVV), with possible implications for the number and timing of pulmonary artery catheter thermodilution measurements. DESIGN: Prospective, clinical pilot study. SETTING: Academic medical center. PARTICIPANTS: Patients who underwent volume-controlled mechanical ventilation and had a pulmonary artery catheter. INTERVENTION: PEEP was increased from 5-to-10 cmH2O and from 10-to-15 cmH2O with 10-minute intervals, with similar decreases in PEEP, from 15-to-10 cmH2O and 10-to-5 cmH2O. MEASUREMENTS AND MAIN RESULTS: In 15 patients, right ventricular parameters were measured using thermodilution at 10% intervals of the ventilatory cycle at each PEEP level with a rapid-response thermistor. Mean right ventricular stroke volume and end-diastolic volume declined during incremental PEEP and normalized on return to 5 cmH2O PEEP (p = 0.01 and p = 0.001, respectively). Right ventricular SVV remained unaltered by changes in PEEP (p = 0.26), regardless of incremental PEEP (p = 0.15) or decreased PEEP (p = 0.12). The coefficients of variation in the ventilatory cycle of all other thermodilution-derived right ventricular parameters also were unaffected by changes in PEEP. CONCLUSIONS: This study showed that increases in PEEP did not affect right ventricular SVV in critically ill patients undergoing mechanical ventilation despite reductions in mean right ventricular stroke volume and end-diastolic volume. This could be explained by cyclic counteracting changes in right ventricular preloading and afterloading during the ventilatory cycle, independent of PEEP. Changes in PEEP did not affect the number and timing of pulmonary artery catheter thermodilution measurements.

The effect of different levels of realism of context learning on the prescribing competencies of medical students during the clinical clerkship in internal medicine: an exploratory study.

PURPOSE: The aim of this study is to evaluate the effect of different levels of realism of context learning on the prescribing competencies of medical students during the clinical clerkship in internal medicine. METHODS: Between 2001 and 2007, 164 medical students took part in the prospective explorative study during their clinical clerkship in internal medicine at the VU University Medical Center, Amsterdam, The Netherlands. In a fixed order, each student had to formulate a treatment plan for a real patient in three situations of increasing realism: a minimal level (studying a patient record), medium level (preparing for a therapeutic consultation), and optimal level (preparing for and performing a therapeutic consultation with the patient). RESULTS: In comparison to studying a patient record (minimal context level), preparing a therapeutic consultation (medium context) improved four of the six steps of the WHO six-step plan. Preparing and performing a therapeutic consultation with a real patient (optimal context) further improved three essential prescribing competencies, namely checking for contraindications and interactions, prescription writing, and instructions to the patient. CONCLUSION AND RECOMMENDATIONS: The results of this first explorative study suggest that enrichment of the learning context (responsibility for patient care) might be an important factor to improve the training of rational prescribing skills of medical students during their clinical clerkship in internal medicine. Clinical (pharmacology) teachers should be aware that seemingly small adaptations in the learning context of prescribing training during clinical clerkships (i.e., with or without involvement with and responsibility for patient care) may have relatively large impact on the development of prescribing competencies of our future doctors.