Background: Ion mobility spectrometry (IMS) allows for online quantification of exhaled propofol concentrations. We aimed to validate a bedside online IMS device, the Edmon ® , for predicting plasma concentrations of propofol in normal-weight and obese patients. Methods:Patients with body mass index (BMI) >20 kg/m 2 scheduled for laparoscopic cholecystectomy or bariatric surgery were recruited. Exhaled propofol concentrations (C A ), arterial plasma propofol concentrations (C P ) and bispectral index (BIS) values were collected during target-controlled infusion (TCI) anaesthesia. Generalised estimation equation (GEE) was applied to all samples and stable-phase samples at different delays for best fit between C P and C A . BMI was evaluated as covariate. BIS and exhaled propofol correlations were also assessed with GEE.Results: A total of 29 patients (BMI 20.3-53.7) were included. A maximal R 2 of 0.58 was found during stable concentrations with 5 min delay of C A to C P ; the intercept a = −0.69 (95% CI −1.7, 0.3) and slope b = 0.87 (95% CI 0.7, 1.1). BMI was found to be a non-significant covariate. The median absolute performance error predicting plasma propofol concentrations was 13.4%. At a C A of 5 ppb, the model predicts a C P of 3.6 μg/ml (95% CI ±1.4). There was a maximal negative correlation of R 2 = 0.44 at 2-min delay from C A to BIS. Conclusions: Online monitoring of exhaled propofol concentrations is clinically feasible in normal-weight and obese patients. With a 5-min delay, our model outperforms the Marsh plasma TCI model in a post hoc analysis. Modest correlation with plasma concentrations makes the clinical usefulness questionable. Editorial CommentMeasurement of exhaled propofol concentration and correlation to drug pharmacodynamics for patients in different weight categories is needed to see if the tool has general clinical value. This trial provides further experience with this method.

A case with cerebral venous air embolism (CVAE) after neurosurgery and treated with hyperbaric oxygen therapy (HBOT) is presented. This is a rare and potentially fatal complication that neurosurgeons should be aware of. A 52-year-old male was diagnosed with an intracerebral hematoma. An emergency evacuation of the hematoma was performed with a craniotomy and the postoperative CT scan showed a complete evacuation of the hematoma, but it also revealed a CVAE. The patient was immediately referred to HBOT and received three sessions within 48 h. The CT scan after the first HBOT showed no CVAE, venous thrombosis, or new hematoma.

Background and Aims Calcific uremic arteriolopathy (CUA), also referred to as calciphylaxis, is a rare and serious complication in patients with advanced kidney disease. CUA has limited treatment options and poor prognosis, with one- year survival often reported to be below 50% after diagnosis [1,2]. Hyperbaric oxygen therapy (HBOT) may improve wound healing by increasing tissue oxygenation, and has been suggested as adjuvant treatment for CUA patients [3]. We added HBOT to our conventional multidisciplinary care of CUA patients in 2012 and this study aims to evaluate long- term outcomes of CUA patients after this. Method Data from all CUA patients treated at our institution from 2012 to 2022 were retrospectively retrieved from hospital records. This is a single-centre study, but patients from different Norwegian hospitals were referred for treatment at our centre. Conventional multidisciplinary care of CUA in our centre included sodium-thiosulphate, dialysis if indicated medical optimization of calcium- phosphate homeostasis, substitution of vitamin K2, withdrawal of warfarin and iron and vitamin D if used, minimization of systemic steroids, in addition to optimization of weight- and nutritional status. Our centre is restrictive with surgical revisions to CUA patients. Results 25 CUA patients received a total number of 1493 HBOT treatments in addition to conventional CUA multidisciplinary care in the study period. Median HBOT per patient was 45 (range 1–267). One year after CUA diagnosis, 20 out of 25 patients were alive (80%). Fifteen out of the 20 patients, who were alive at one year after CUA diagnosis, had completely resolved CUA lesions (75%). Five patients died within the first year after CUA diagnosis, due to acute cardiovascular disease (n = 3) and infection (n = 2). Our impression is that HBOT is well- tolerated and associated with less wound- associated pain. Conclusion Our results suggest that HBOT is well- tolerated in CUA patients. After we included HBOT in our multidisciplinary care of CUA patients, 80% of the patients were alive one- year after CUA diagnosis.