Anaesthesia
-
Multicenter Study
The effect of fresh gas flow during induction of anaesthesia on sevoflurane usage: a quality improvement study.
Modest reductions in fresh gas flow at the beginning of anaesthesia induction results in meaningful reduction in sevoflurane consumption.
pearl -
Randomized Controlled Trial
Assessment of gastric emptying of maltodextrin, coffee with milk and orange juice during labour at term using point of care ultrasound: a non-inferiority randomised clinical trial.
Labouring women have been shown to have slower gastric emptying than non-pregnant subjects, and this argument is sometimes used to recommend fasting guidelines such as nil-by-mouth during labour. We performed a parallel group, randomised non-inferiority trial, comparing gastric emptying of 450 ml isocalorically-adjusted maltodextrin, coffee with milk or pulp-free orange juice, with 18 women in each group. The women were initially fasted for 2 h for clear fluids, 6 h for a light meal and 8 h for a high fat or high protein meal. ⋯ The estimated gastric residual volume was lower than baseline from 90 min after drinking maltodextrin. In labouring women, maltodextrin is cleared from the stomach faster than coffee with milk and orange juice. Gastric emptying depends on other factors besides the caloric load and volume of the drink.
-
Although bedside screening tests are routinely used to identify people at high risk of having a difficult airway, their clinical utility is unclear. We estimated the diagnostic accuracy of commonly used bedside examination tests for assessing the airway in adult patients without apparent anatomical abnormalities scheduled to undergo general anaesthesia. We searched for studies that reported our pre-specified bedside index screening tests against a reference standard, published in any language, from date of inception to 16 December 2016, in seven bibliographic databases. ⋯ For difficult laryngoscopy, the sensitivity and specificity (95%CI) of the upper lip bite test were 0.67 (0.45-0.83) and 0.92 (0.86-0.95), respectively; upper lip bite test sensitivity (95%CI) was significantly higher than that for the mouth opening test (0.22, 0.13-0.33; p < 0.001). For difficult tracheal intubation, the modified Mallampati test had a significantly higher sensitivity (95%CI) at 0.51 (0.40-0.61) compared with mouth opening (0.27, 0.16-0.41; p < 0.001) and thyromental distance (0.24, 0.12-0.43; p < 0.001). Although the upper lip bite test showed the most favourable diagnostic test accuracy properties, none of the common bedside screening tests is well suited for detecting unanticipated difficult airways, as many of them are missed.
-
We assessed the impact of raising the upper section of the bed, and patient positioning, on ultrasound assessment of gastric fluid contents. We performed ultrasound examinations in 25 subjects lying on their back, left and right sides at bed angles of 0°, 30°, 45° and 90°; this was carried out while the subjects were fasted, and repeated 10 min after drinking ≥ 50 ml water. After drinking, gastric contents were detected more frequently in the 45° semirecumbent position compared with the supine and 30° positions. ⋯ Antral cross-sectional area was significantly increased when measured in the right lateral position, but there was no effect of raising the bed. In conclusion, raising the upper section of the bed significantly affected qualitative assessment of gastric fluid contents. Further studies are required to determine the most appropriate composite ultrasound grading scale and bed angle for fast and reliable qualitative ultrasound detection of fluid volumes > 1.5 ml.kg-1 .
-
We investigated whether low melting point phase-change waxes could be incorporated into emergency drug transport bags to attenuate the known temperature extremes their contents can be exposed to. We exposed two custom-made hollow-walled drug containers placed within a pair of drug transport bags to three day/night cycles including periods of direct radiant sunlight. The wall cavities of one contained air, whereas those of the other contained a paraffin wax (melting point of 44-46 °C) with a high latent heat of fusion (until fully melted, its temperature does not increase further). ⋯ Even when they did so, their temperature was attenuated to 40.3 °C, despite an ambient air temperature of > 40 °C for 6.4% of the time (peak 46.9 °C) and a bag surface temperature of > 40 °C for 17.2% of the time (peak 64.4 °C). In contrast, the ampoule temperature in the air cavity container exceeded 40 °C for 17.1% of the time (peak 54.1 °C). The latent heat of fusion of phase-change materials may be exploited in the design of drug transport bags to mitigate any temperature changes in the drugs stored within them.