Sex difference and intra-operative tidal volume: Insights from the LAS VEGAS study

BACKGROUND: One key element of lung-protective ventilation is the use of a low tidal volume (VT). A sex difference in use of low tidal volume ventilation (LTVV) has been described in critically ill ICU patients.OBJECTIVES: The aim of this study was to determine whether a sex difference in use of LTVV also exists in operating room patients, and if present what factors drive this difference.DESIGN, PATIENTS AND SETTING: This is a posthoc analysis of LAS VEGAS, a 1-week worldwide observational study in adults requiring intra-operative ventilation during general anaesthesia for surgery in 146 hospitals in 29 countries.MAIN OUTCOME MEASURES: Women and men were compared with respect to use of LTVV, defined as VT of 8 ml kg-1 or less predicted bodyweight (PBW). A VT was deemed 'default' if the set VT was a round number. A mediation analysis assessed which factors may explain the sex difference in use of LTVV during intra-operative ventilation.RESULTS: This analysis includes 9864 patients, of whom 5425 (55%) were women. A default VT was often set, both in women and men; mode VT was 500 ml. Median [IQR] VT was higher in women than in men (8.6 [7.7 to 9.6] vs. 7.6 [6.8 to 8.4] ml kg-1 PBW, P < 0.001). Compared with men, women were twice as likely not to receive LTVV [68.8 vs. 36.0%; relative risk ratio 2.1 (95% CI 1.9 to 2.1), P < 0.001]. In the mediation analysis, patients' height and actual body weight (ABW) explained 81 and 18% of the sex difference in use of LTVV, respectively; it was not explained by the use of a default VT.CONCLUSION: In this worldwide cohort of patients receiving intra-operative ventilation during general anaesthesia for surgery, women received a higher VT than men during intra-operative ventilation. The risk for a female not to receive LTVV during surgery was double that of males. Height and ABW were the two mediators of the sex difference in use of LTVV.TRIAL REGISTRATION: The study was registered at Clinicaltrials.gov, NCT01601223

Benefit of the minimal invasive ultrasound-guided single shot femoro-popliteal block for ankle surgery in comparison with spinal anesthesia

BACKGROUND: Ultrasound-guided regional anesthesia has gained popularity for ankle and foot surgery. The aim of our study was to investigate the sufficiency of anesthesia for ankle surgery as well as duration of analgesia in postoperative period, using minimal invasive ultrasound-guided regional anesthesia, and to compare it with anesthesia and postoperative analgesia following spinal anesthesia. METHODS: This prospective study included 40 adult trauma patients with bimalleolar fracture who were scheduled for surgery. They were randomly assigned and divided in two groups. Patients from the first group underwent an Ultrasound-guided femoro-popliteal block (US-FPB), while a spinal anesthesia (SA) was performed for the second group. The local anesthetic 0.5% bupivacaine was used in both groups. RESULTS: Eighteen patients from the first and nineteen patients from the second group completed the study. Levels of anesthesia were sufficient in both groups without significant differences. Duration of postoperative analgesia was significantly higher in US-FPB group in comparison to SA group (12 ± 3 vs. 3 ± 1 h) (p < 0.001). At the same time, onset of complete sensory motor block was significantly faster in SA group in comparison to US-FPB group (5 ± 1 vs. 8 ± 3 min) (p < 0.001). CONCLUSION: Minimal invasive US-FPB provides sufficient anesthesia for ankle fracture. In comparison to the SA group, patients from the US-FPB group achieved significantly longer postoperative analgesia, while faster onset of anesthesia was noted in SA group

Influence of arm position on ultrasound visibility of the axillary brachial plexus

BACKGROUND Contemporary axillary brachial plexus block is performed by separate injections targeting radial, median, ulnar and musculocutaneous nerve. These nerves are arranged around the axillary artery, making ultrasound visualisation sometimes challenging. In particular, the radial nerve can be difficult to localise deep to the artery. OBJECTIVES The primary aim of this study was to investigate which arm position optimises the visibility of the radial nerve. Secondary aims were the visibility and position of the other nerves during varying arm positions. DESIGN A prospective observational study. SETTING University teaching hospital, November 2012. PARTICIPANTS Twenty volunteers, recruited by an advertisement on the Department's bulletin board. Inclusion criterion age more than 18 years. Exclusion criteria: refusal of ultrasound examination, restricted shoulder movement, local infection, BMI greater than 30 kgm(-2). INTERVENTION One anaesthesiologist performed bilateral ultrasound examinations of the axillary brachial plexus on 20 volunteers. Each arm was placed in different positions [shoulder (S) 90 degrees or 180 degrees abduction, elbow (E) 0 degrees or 90 degrees extension] and scans were performed proximally in the axilla, and additionally 5cm distally to this point [proximal (P) vs. distal (D)], resulting in eight different scans stored for off-line analysis performed by two blinded anaesthesiologists. MAIN OUTCOME MEASURES For radial, median, ulnar and musculocutaneous nerve, visibility was assessed on a sixpoint visibility scale. Distances and angles of the nerves relative to the axillary artery and distances relative to the skin were measured. RESULTS No significant differences between arm positions were found in the visibility score of radial (P = 0.359) and musculocutaneous nerves (P = 0.073). Visibility of the median nerve was improved in positions S90 degrees/E0 degrees/D and S180 degrees/E0 degrees/P (P = 0.02). The ulnar nerve was more visible in position S180 degrees/E 0 degrees/P and D (P = 0.007). The greatest distance between artery and radial nerve was 7.4 +/- 4.7mm at an angle of 120 +/- 14 degrees in position S180 degrees/E 0 degrees/D. CONCLUSION The visibility of the radial nerve was not improved by varying positions of the arm. S180 degrees/E0 degrees provided the best overall visibility and accessibility of nerve