Summary Surgical drapes used during eye surgery are impermeable to air and hence risk trapping air underneath them. We investigated the effect of a forced‐air warming blanket on carbon dioxide accumulation under the drapes in patients undergoing eye surgery under local anaesthesia without sedation. Forty patients of ASA physical status 1 and 2 were randomly assigned to either the forced‐air warmer (n = 20) or a control heated overblanket (n = 20). All patients were given 1 l.min−1 oxygen. We measured transcutaneous and end‐tidal carbon dioxide partial pressures, heart rate, arterial pressure, respiratory rate, temperature and oxygen saturation before and after draping, then every 5 min thereafter for 30 min. The mean (SD) transcutaneous carbon dioxide partial pressure in the forced‐air warming group stayed constant after draping at 5.7 (0.2) kPa but rose to a maximum of 6.4 (0.4) kPa in the heated overblanket group (p = 0.0001 for the difference at time points 15 min and later). We conclude that forced‐air warming reduces carbon dioxide accumulation under the drapes in patients undergoing eye surgery under local anaesthesia.

The aim of this randomised, controlled trial was to determine the optimum dose of fentanyl in combination with propofol 2.5 mg.kg-1 when inserting the Classic™ Laryngeal Mask Airway. Seventy-five ASA I or II patients were randomly assigned to five groups of fentanyl dosage: 0 µg.kg-1 (placebo), 0.5 µg.kg-1 , 1.0 µg.kg-1 , 1.5 µg.kg-1 and 2.0 µg.kg-1. Anaesthesia was induced by first injecting the study drug over 10 seconds. Three minutes after the study drug was injected, propofol (2.5 mg.kg-1) was injected over 10 seconds. The Classic™ Laryngeal Mask Airway was inserted four minutes and 30 seconds after injection of the study drug. Insertion conditions were evaluated using a four-category score. Thirty-nine males and 36 females aged 19 to 59 years were studied. The incidence of prolonged apnoea increased as fentanyl dose increased. We found that there was a high rate of successful first attempt at insertion with 1 µg.kg-1 and 1.5 µg.kg-1 , 93% and 87% respectively, compared to 87% in the 2.0 µg.kg-1 group. The 1.0 µg.kg-1 group also achieved an 80% optimal insertion conditions score of 4, compared to 73% in the 1.5 µg.kg-1 group and 80% in the 2 µg.kg-1 group. Therefore we recommend 1.0 µg.kg-1 as the optimal dose of fentanyl when used in addition to propofol 2.5 mg/kg for the insertion of the Classic™ Laryngeal Mask Airway.

BackgroundMinimally invasive surgery is becoming more common and transfemoral transcatheter aortic valve replacement is offered to older patients with multiple comorbidities. Sternotomy is not required but patients must lie flat and still for up to 2 – 3 hours. This procedure is increasingly being performed under conscious sedation with supplementary oxygen, but hypoxia and agitation are commonly observed.MethodsIn this randomised controlled trial, we hypothesised that high-flow nasal oxygen would provide superior oxygenation as compared with our standard practice, 2 l.min-1 oxygen by dry nasal specs. The primary endpoint was the change in arterial partial pressure of oxygen (PaO2) during the procedure. Secondary outcomes included the incidence of oxygen desaturation and patient movements. Results A total of 72 patients were recruited. There was no difference in change in PaO2 from baseline using high-flow compared with standard oxygen therapy: median [IQR] increase from 12.1 (10.0- 15.3 [7.2- 29.8]) to 13.7 (10.8- 18.7 [8.5- 32.3]) kPa vs. decrease from 15.5 (12.4- 19.4 [9.2- 22.8]) to 14.2 (11.9- 19.3 [9.7- 22.8]) kPa, respectively (p= 0.087). There was a lower incidence of oxygen desaturation in the high-flow group (p= 0.037). Patients in the high-flow group moved less frequently (p= 0.006) and assigned a significantly higher comfort score to their treatment (p= < 0.001). ConclusionThis study has demonstrated that high-flow, compared with standard oxygen therapy, does not improve arterial oxygenation over the course of the procedure. There are suggestions that it may improve the secondary outcomes studied. Trial registrationInternational Standard Randomised Controlled Trial Number (ISRCTN) 13804861. Registered 15/4/2019. https://doi.org/10.1186/ISRCTN13804861