Responses to nitrite are further enhanced under hypoxic conditions in resistance arterioles (FBF). 3,4 Indeed, all the nitrite reductases identified to date display selective activity under conditions of hypoxia or ischemia 5 , including the other globins (myoglobin, cytoglobin, and neuroglobin), xanthine oxidase, endothelial NO synthase, and aldehyde oxidase (AO). [6][7][8] Conversely, oxygenated hemoglobin and myoglobin are avid scavengers of nitrite-derived NO, suggesting that an intricate balance exists between production and consumption. [7][8][9] Most antihypertensive vasodilators selectively dilate small resistance arterioles, 10 (mainly reducing peripheral blood pressure [BP]). Notable exceptions are the organic nitrates, eg, glyceryl trinitrate (GTN), a selective dilator of muscular conduit arteries, 10-12 the accepted mechanism by which GTN Background-Inorganic nitrite dilates small resistance arterioles via hypoxia-facilitated reduction to vasodilating nitric oxide. The effects of nitrite in human conduit arteries have not been investigated. In contrast to nitrite, organic nitrates are established selective dilators of conduit arteries. Methods and Results-We examined the effects of local and systemic administration of sodium nitrite on the radial artery (a muscular conduit artery), forearm resistance vessels (forearm blood flow), and systemic hemodynamics in healthy male volunteers (n=43). Intrabrachial sodium nitrite (8.7 μmol/min) increased radial artery diameter by a median of 28.0% (25th and 75th percentiles, 25.7% and 40.1%; P<0.001). Nitrite (0.087-87 μmol/min) displayed conduit artery selectivity similar to that of glyceryl trinitrate (0.013-4.4 nmol/min) over resistance arterioles. Nitrite dose-dependently increased local cGMP production at the dose of 2.6 μmol/min by 1.1 pmol·min −1 ·100 mL −1 tissue (95% confidence interval, 0.5-1.8). Nitriteinduced radial artery dilation was enhanced by administration of acetazolamide (oral or intra-arterial) and oral raloxifene (P=0.0248, P<0.0001, and P=0.0006, respectively) but was inhibited under hypoxia (P<0.0001) and hyperoxia (P=0.0006) compared with normoxia. Systemic intravenous administration of sodium nitrite (8.7 μmol/min) dilated the radial artery by 10.7% (95% confidence interval, 6.8-14.7) and reduced central systolic blood pressure by 11.6 mm Hg (95% confidence interval, 2.4-20.7), augmentation index, and pulse wave velocity without changing peripheral blood pressure. Conclusions-Nitrite selectively dilates conduit arteries at supraphysiological and near-physiological concentrations via a normoxia-dependent mechanism that is associated with cGMP production and is enhanced by acetazolamide and raloxifene. The selective central blood pressure-lowering effects of nitrite have therapeutic potential to reduce cardiovascular events.

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Between 1971 and 1991, details of 67 women with perianal Crohn's disease were recorded prospectively using the Cardiff classification. Two groups were identified according to the presence (n = 29) or absence (n = 38) of anorectal Crohn's fistula involving the vagina. Patients in both groups were of a similar age and had had Crohn's disease for a similar period before diagnosis of perianal involvement. The incidence of associated perianal lesions, superficial ulcers, cavitating ulcers, other fistulas and strictures was not significantly different between the two groups. A greater proportion of patients with anorectal-vaginal fistulation (n = 15) had distal intestinal Crohn's disease (rectal or contiguous colorectal) compared with women with no vaginal fistulation (n = 14). A range of therapies was used to manage women with perianal Crohn's disease, from local surgery to a defunctioning stoma and/or proctectomy. Only 13 of 38 women with perianal Crohn's disease but no vaginal fistula required a defunctioning stoma or proctectomy, whereas 18 of 29 with anorectal-vaginal fistulation underwent these procedures (P < 0.05). A vaginal fistula has a considerable adverse effect on the outcome of perianal Crohn's disease.

No abstract

After a quadratus lumborum (QL) block, the course of QL plane catheter is unpredictable. This case series discusses the course and fate of trans-muscular QL catheters by following and discussing the contrast spread through the fascial planes. Intrao-peratively, the catheters were tracked by the surgeons and were checked for integrity of anterior thoracolumbar fascia (ATLF) by injecting sterile 0.9% saline. The ATLF was intact upon injection and there was cephalad and medial saline spread with slight bulging of ATLF. On day 3 after written informed consent from all patients, computed tomography (CT) contrast studies were performed. Post-operative contrast spread was variable and was visualised in transversus abdominis plane, QL plane, lower thoracic paravertebral space, inter-vertebral foramina and anterior epidural space. CT contrast images demonstrated a variable spread. In conclusion, injection in ATLF of QL can spread along the path of least resistance and is unpredictable.

Difficult airway management continues to adversely affect patient care and clinical outcomes and is poorly predicted. Previous difficult airway management is the most accurate predictor of future difficulty. The Difficult Airway Society initiated a national airway database to allow clinicians to access details of previous difficult airway episodes in patients issued with a difficult airway alert card. We aimed to analyse this database, reporting patient characteristics, airway management and patient outcomes. We included all living adult patients reported in the first 5 years of the database (n = 675). Clinical airway assessment was reported in 634 (94%) patients, with three or more parameters assessed in 488 (72%). A history of difficult airway was known in 136 (20%) patients and difficult airway management was anticipated in 391 (58%). In all, 75 (11%) patients had an airway-related critical incident, with 1 in 29 being awoken from anaesthesia, 1 in 34 requiring unplanned or prolonged stay in the intensive care unit and 1 in 225 needing an emergency front-of-neck airway or had a cardiac arrest/peri-arrest episode. Airway-related critical incidents were associated with out-of-hours airway management, but no other associations were apparent. Our data report the first analysis of a national difficult airway database, finding that unanticipated difficult airway management continues to occur despite airway assessment, and the rate of critical incidents in this cohort of patients is high. This database has the potential to improve airway management for patients in the future.

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Cricoid pressure is employed during rapid sequence induction to reduce the risk of pulmonary aspiration. Correct application of cricoid pressure depends on knowledge of neck anatomy and precise identification of surface landmarks. Inaccurate localisation of the cricoid cartilage during rapid sequence induction risks incomplete oesophageal occlusion, with potential for pulmonary aspiration of gastric contents. It may also compromise the laryngeal view for the anaesthetist. Accurate localisation of the cricoid cartilage therefore has relevance for the safe conduct of rapid sequence induction. We conducted a multicentre, prospective cohort study to determine the accuracy of cricoid cartilage identification in 100 patients. The cranio-caudal midpoint of the cricoid cartilage was identified by a qualified anaesthetic assistant using the conventional landmark technique and marked. While maintaining the patient in the same position, a second mark was made by identifying the midpoint of the cricoid cartilage using ultrasound scanning. The mean (SD) distance between the two marks was 2.07 (8.49) mm. In 41% of patients the midpoint was incorrectly identified by a margin greater than 5 mm. This error was uniformly distributed both above and below the midpoint of the cricoid cartilage. The Pearson correlation coefficient of this error with respect to body mass index was 0.062 (p = 0.539) and with age was -0.020 (p = 0.843). There were also no significant differences in error between male and female patients. Identification of cricoid position using a landmark technique has a high degree of variability and has little correlation with age, sex or body mass index. These findings have significant implications for the safe application of cricoid pressure in the context of rapid sequence induction.