Anaesthesia and Intensive Care最新文献

Tracheal intubation over a flexible guide is an essential skill for those managing difficult airways in anaesthesia and critical care. However, there may be difficulty railroading the tube over the guide due to impingement of the tube bevel entering the larynx. This may lead to repeated intubation attempts, possible trauma, possible failed intubation and hypoxia if alternative ventilation is not ensured. In this prospective observational study, we investigated the effectiveness of tracheal intubation without impingement over a guidewire already in place. Our direct wire-guided intubation system consists of a modified reinforced silicone tracheal tube with a guide channel in its wall to accommodate a matched kink-resistant guidewire as the introducer. We studied 299 American Society of Anesthesiologists Physical Status classification 1-3 patients with a predicted low risk of difficult intubation. Significant impingement occurred in one patient due to a deep laryngeal fissure (0.3%, upper limit of 95% confidence interval 1.9%). Laryngeal tube transit was graded 'not difficult' in 284 patients (95%), and 'mildly difficult' in 14 (4.7%). Tube transit between oropharynx and glottis offered no resistance in 294 patients (98.3%) and mild resistance in five (1.7%). There were no oesophageal misplacements of the tube. Our system appears effective to facilitate guidewire-assisted tracheal intubation in patients at predicted low risk of difficult intubation when a guidewire is already in place. Further studies are required in patients with predicted difficult intubation.

Venous thromboembolism (VTE), encompassing deep vein thrombosis and pulmonary embolism, contributes significantly to morbidity and mortality in critically ill patients. This increased incidence is influenced by factors such as indwelling central venous catheters, continuous sedation, and vasoactive infusions, in addition to traditional VTE risk factors such as immobility. Optimal VTE prophylaxis remains uncertain owing to significant variability with regard to differences across existing randomized controlled trials (RCTs) in terms of patient populations, types and dosing of prophylactic interventions, and definitions of VTE outcomes. RCTs conducted on critically ill patients are often limited by over-optimistic estimates of baseline event rates and potential treatment benefit. We conducted a systematic review to evaluate the described sample size methodologies and justification amongst VTE-prevention RCTs for critically ill patients. We searched MEDLINE and Embase from inception until 9 September 2024, and included 12 RCTs enrolling 9154 patients. Sample sizes ranged from 36 to 3746 participants. Only six studies met their recruitment targets, while four did not report a sample size calculation. Among the seven studies that reported an estimated control event rate, only one met that estimate. No studies achieved their planned absolute risk reduction, and only one met its relative risk reduction target. Prognostic enrichment strategies were employed in 41.6% of trials, while predictive enrichment was rarely used. These findings suggest that intensive care unit VTE prophylaxis trials frequently overestimate baseline risk and treatment effect size, contributing to underpowered studies and potential premature abandonment of promising interventions. Future trials should incorporate enrichment strategies and justify assumptions based on clinical relevance and patient-centred outcomes.

Awake tracheal intubation (ATI) is advocated in situations where complex airway anatomy or deranged physiology make usual post-induction airway management hazardous. The safety of ATI has been described in many settings. Nevertheless, it is not always performed when indicated, and significant patient harm as a consequence is still reported. A survey was conducted to investigate anaesthetists' practices and possible reasons for reticence in performing ATI. The survey also sought to explore solutions to limited opportunities for training and skills maintenance. The 17-question survey was sent to a random selection of 1400 consultant anaesthetists across Australia and New Zealand in 2023. The response rate was 36% (499 of 1400). Forty percent (198 of 499) (95% confidence interval (CI) 35 to 44) of participants had not performed an ATI in the last 12 months. The majority of participants (64% (317 of 499) (95% CI 59 to 68)) agreed that there were barriers in their own practice to performing ATI. There was strong agreement that proficiency in ATI should be within the skillset of on-call anaesthetists (81% (400 of 494) (95% CI 78 to 84)). There was also strong support for ATI to become a mandatory core skill (74% (368 of 497) (95% CI 70 to 78) of participants). Current volume of practice for trainees was almost universally considered insufficient (93% (459 of 496) (95% CI 90 to 95)). There is a disparity between the perceived importance of competence in ATI and the limited volume of practice expected of trainees and paucity of ongoing clinical exposure for consultants. Training and programs to maintain skills in ATI are urgently required to address this.

Nitrous oxide (N₂O) is a potent greenhouse gas used to provide analgesia and anaesthesia in healthcare. Leaks from the manifold-pipeline systems may result in significant losses of N₂O before delivery to the patient. The provision of N₂O by cylinder at point-of-care is proposed as a leak-reducing alternative to manifold-pipeline systems. The primary endpoint of this study was to determine the percentage of anaesthetists who considered it acceptable for N₂O to be supplied by cylinder rather than a manifold-pipeline system. It also explored the current application of N₂O and prevailing attitudes toward its environmental impact and future role in anaesthetic practice. A cross-sectional survey was administered in 2023 among anaesthetists working across seven metropolitan hospitals in New South Wales, Australia. Participants provided self-reported information on demographics, practice characteristics, views on climate change, the role of anaesthetists in addressing environmental concerns, routine N₂O usage, and the potential shift to cylinder supply of N₂O. Among the 287 respondents, the majority (n=241, 84.6%) were current users of N₂O, although most administered it infrequently (71.5% used it in less than 25% of cases). Attitudes regarding N₂O's environmental impact varied irrespective of career stage. Notably, 219 of 287 (76.3%) favoured using cylinders over the manifold-pipeline network. These findings indicate a decreasing trend in N₂O usage, especially among early career anaesthetists, and suggest that transitioning to cylinder supply is acceptable, provided that strategies are in place to manage supply disruptions without compromising patient care.

Remifentanil and dexmedetomidine are sedative agents used both in anaesthetic and critical care practice. Their effects on the gastro-oesophageal pressure gradient and hence on the potential risk for regurgitation have not been quantified. The aim of this study was to measure and compare the effects of both agents on the gastro-oesophageal pressure gradient. The study used a randomised, double blinded crossover study design, and 16 healthy volunteers were sedated on two separate occasions. Baseline lower oesophageal sphincter pressure (26 and 28 mmHg for dexmedetomidine and remifentanil, respectively) and gastro-oesophageal pressure gradient (20 mmHg for both dexmedetomidine and reminfentanil) were recorded. Then, each volunteer received increasing doses of target-controlled infusions of dexmedetomidine (1, 2, 4, 6 ng/ml) or remifentanil (1, 2, 3, 4 ng/ml). Each dose level was maintained for 20 minutes, and both lower oesophageal sphincter pressure and gastro-oesophageal pressure gradient were continuously recorded. Measurements were averaged. Out of 16 subjects recruited, data were analysable from 11 (aged 18-54 years, body mass index 17.7-27.9 kg/m², five men and six women). The dose regimens of both agents provided similar profiles of progressive sedation over time, with sedation scores reaching a minimum of -2 on the 'observer's assessment of alertness and sedation score' with both medications. With dexmedetomidine, the bispectral index gradually decreased in line with sedation scores (P<0.05), but remifentanil produced little change in the bispectral index from baseline. Both agents decreased gastro-oesophageal pressure gradient (P<0.001) similarly, (P=0.199), in line with the decreases in sedation scores. In conclusion, when remifentanil or dexmedetomidine are administered to provide sedation they induce similar decreases in gastro-oesophageal pressure gradient. This may put patients at comparable risk of gastro-oesophageal reflux.

2,4-Dinitrophenol (DNP), previously used as a weight loss drug, was banned owing to its narrow therapeutic index and severe side effects. DNP disrupts mitochondrial oxidative phosphorylation and inhibits adenosine triphosphate synthesis, causing heat production, increased basal metabolic rate and enhanced glycolysis. Despite bans, unregulated online and darknet sales have led to a rise in DNP toxicity cases. We report a case of a young man who survived a deliberate, highly lethal DNP overdose through coordinated team-based care including early aggressive cooling and high-volume mechanical ventilation, crucial in maintaining normothermia and normocapnia. This case adds valuable insights to the literature on DNP toxicity management.