The assessment of circulating volume using inferior vena cava collapse index and carotid Doppler velocity time integral in healthy volunteers: a pilot study.

BACKGROUND: Assessment of circulating volume and the requirement for fluid replacement are fundamental to resuscitation but remain largely empirical. Passive leg raise (PLR) may determine fluid responders while avoiding potential fluid overload. We hypothesised that inferior vena cava collapse index (IVCCI) and carotid artery blood flow would change predictably in response to PLR, potentially providing a non-invasive tool to assess circulating volume and identifying fluid responsive patients. METHODS: We conducted a prospective proof of concept pilot study on fasted healthy volunteers. One operator measured IVC diameter during quiet respiration and sniff, and carotid artery flow. Stroke volume (SV) was also measured using suprasternal Doppler. Our primary endpoint was change in IVCCI after PLR. We also studied changes in IVCCI after "sniff", and correlation between carotid artery flow and SV. RESULTS: Passive leg raise was associated with significant reduction in the mean inferior vena cava collapsibility index from 0.24 to 0.17 (p < 0.01). Mean stroke volume increased from 56.0 to 69.2 mL (p < 0.01). There was no significant change in common carotid artery blood flow. Changes in physiology consequent upon passive leg raise normalised rapidly. DISCUSSION: Passive leg raise is associated with a decrease of IVCCI and increase in stroke volume. However, the wide range of values observed suggests that factors other than circulating volume predominate in determining the proportion of collapse with respiration. CONCLUSION: In contrast to other studies, we did not find that carotid blood flow increased with passive leg raise. Rapid normalisation of post-PLR physiology may account for this.

Emergency department procedural sedation: the London experience.

AIM: The aim of this study was to develop a procedural sedation guideline and an audit tool to identify the medications chosen, the incidence of predefined adverse events and the factors associated with their occurrence. METHODS: We performed a prospective observational study using a standardized proforma. We obtained data on patient demographics, the procedure performed, the drugs used and the dosages and predefined adverse events. Our target population was adult patients attending three urban UK teaching hospital Emergency Departments (EDs) over a 12-month period. We included all patients who were to undergo procedural sedation in the ED. RESULTS: Data were obtained on 414 patients. The majority of procedures were reductions of fractures and dislocations (89%). Midazolam was the sedative agent used most commonly (45%), and morphine was the most frequently used analgesic agent (36%). Overall 10% of sedations involved predefined complications (95% confidence interval: 7.1-12.9). There were no cases of airway obstruction requiring intervention; no patients showed clinical evidence of aspiration and no patient required intubation. Procedural success was 96%. Propofol was associated with fewer adverse events (95% confidence interval: 0.024-0.572), as well as higher procedural success. CONCLUSION: Procedural sedation and analgesia can be safely and effectively performed in the ED by appropriately trained emergency physicians.

Best approach to measuring the inferior vena cava in spontaneously ventilating patients: a pilot study.

The objective of this study was to establish the reliability of different measurements of inferior vena cava (IVC) size and respiratory variation in response to changes in circulating volume. Transabdominal ultrasound measurements of the IVC were obtained in longitudinal (B and M modes) and transverse planes (B-mode height and ellipse circumference) during inspiration and expiration, and inferior vena cava collapsibility indices (IVCci) were calculated. Measurements were repeated following venesection of ∼450 ml. Thirty patients underwent venesection. Their IVCci increased significantly for transverse and longitudinal height measurements following venesection, but not for transverse circumference measurements. Transverse views were inadequate in 27% of patients, compared with 7% for longitudinal views (P=0.04). Changes in IVCci are sensitive to small changes in circulating volume. Measurements are most frequently achieved in the longitudinal plane. There is an urgent need for standardization of sonographic IVC measurement techniques.

Self-perception of knowledge and confidence in performing basic life support among medical students.

AIM: Before implementing new workshops and teaching in our faculty for performing basic life support (BLS), we aimed to determine the level of self-confidence of medical students with regard to the management of cardiac arrest (CA). METHODS: We conducted a preinterventional study. A questionnaire was sent to third-year to sixth-year medical students. We recorded sex, year of training, and personal witnessing of CA. We asked them about their theoretical knowledge on 10 main items of BLS and their self-perception of qualification to conduct a CA situation. We tested the respective influence of sex, year of training, and personal witnessing of CA. RESULTS: In total, 592 (37%) students completed the questionnaire, 42% of them were men. Less than a third of the students (30%) thought of themselves as being sufficiently qualified to conduct BLS. After the third year, the level of study did not influence their theoretical knowledge or their self-perception of qualification. Male sex and the number of CAs witnessed were the only factors positively associated with better self-confidence regarding qualification. CONCLUSION: Self-perception of qualification in BLS is poor in our faculty. In our study, personal witnessing of CA greatly influenced confidence, whereas level of study did not.