An audit of the diagnostic accuracy of rotational thromboelastometry for the identification of hypofibrinogenaemia and thrombocytopenia during cardiopulmonary bypass.

We audited the diagnostic accuracy of ROTEM® (TEM Innovations, GmbH, Munich, Germany) measurements of hypofibrinogenaemia (fibrinogen <1.5 g/l) and thrombocytopenia (platelet count <100 x 109/l) in 200 adult non-transplant patients during cardiopulmonary bypass (CPB). Blood samples were obtained for FIBTEM (assay for the fibrin part of the clot), PLTEM (calculated platelet-specific component), and laboratory measurements simultaneously. Our thresholds for FIBTEM and PLTEM were A10 (clot firmness 10 minutes after clotting time) ≤8 mm, and <35 mm respectively. We also calculated the accuracy of smaller thresholds and earlier indices. We found that FIBTEM A10 ≤8 mm had low sensitivity (0.62) for hypofibrinogenaemia. With the 13% hypofibrinogenaemia prevalence in our sample, the positive predictive value (PPV) was 0.47. In contrast, FIBTEM A10 ≤8 mm had higher specificity (0.90) (negative predictive value [NPV] 0.94). Of the other FIBTEM values analysed, only A5 ≤6 mm had similar or superior accuracy. The PLTEM results were less encouraging (sensitivity 0.81, specificity 0.62). With our prevalence of thrombocytopenia (also 13%), the PPV was only 0.24. However, the NPV was high (0.96). Of the other PLTEM values analysed, only A5 <25 mm had similar or superior accuracy. These findings indicate that during CPB FIBTEM A10 ≤8 mm and PLTEM A10 <35 mm have greater accuracy in identifying the absence of hypofibrinogenaemia and thrombocytopenia respectively than their presence. On the basis of these results we would be reassured by FIBTEM A10 values >8 mm and PLTEM A10 values ≥35 mm, but would continue to use laboratory measurements for confirmation. We would not use FIBTEM A10 ≤8 mm or PLTEM A10 <35 mm values alone to guide replacement therapy unless clinical conditions warranted an immediate decision before laboratory measurements were available.

Prevalence of major vessels anterior to the trachea at sites of potential front-of-neck emergency airway access in adults.

BACKGROUND: Several case reports have described anatomical variations that can cause difficulty with front-of-neck airway access, such as major vessels anterior to the trachea. The prevalence of these anomalies is unknown. METHODS: We screened 500 consecutive thoracic computed tomography (CT) scans in adult patients performed independently in any public hospital in Western Australia. The prevalence of major vessels anterior to the trachea in the anterior triangle of the neck was determined. RESULTS: In the suprasternal notch, 264 CT scans (53%) demonstrated part of a major vessel anterior to the trachea, most commonly the brachiocephalic artery. At 10, 20, and 30 mm above the suprasternal notch, respectively, 126 (25%), 48 (9%), and 5 (1%) CT scans showed a major vessel anterior to the trachea. None showed a major vessel anterior to the cricothyroid membrane. In the suprasternal notch, a major vessel was anterior to the trachea in 10 of 120 CT scans (8%) that had a manubrio-cricoid distance <25 mm, and 108 of 116 CT scans (93%) that had a manubrio-cricoid distance >50 mm. In a logistic-regression model, increased length of trachea above the manubrium was a strong predictor of major vessels anterior to the trachea in the suprasternal notch, whilst sex, age, thoracic kyphosis, tracheal diameter, and the origin of the brachiocephalic artery were not strong predictors. CONCLUSIONS: It is common for patients to have some portion of a major vessel anterior to the trachea at sites where an emergency tracheostomy might be performed.

Patient and procedural factors associated with an increased risk of harm or death in the first 4,000 incidents reported to webAIRS.

This report describes an analysis of patient and procedural factors associated with a higher proportion of harm or death versus no harm in the first 4,000 incidents reported to webAIRS. The report is supplementary to a previous cross-sectional report on the first 4,000 incidents reported to webAIRS. The aim of this analysis was to identify potential patient or procedural factors that are more common in incidents resulting in harm or death than in incidents with more benign outcomes. There was a >50% higher proportion of harm (versus no harm) for incidents in which the patient's body mass index (BMI) was <18.5 kg/m2, for incidents in post-anaesthesia care units and non-theatre procedural areas, and for incidents under the main category of cardiovascular or neurological. The proportion of incidents associated with death was also higher (risk ratio >1.5) for BMI <18.5 kg/m2, incidents in non-theatre procedural areas, and incidents under the main category of cardiovascular or neurological. In addition, the proportion of incidents associated with death was higher for incidents in which the patient's age was >80 years, the American Society of Anesthesiologists physical status was 4 or 5, incidents involving non-elective procedures, and incidents occurring after hours (1800 to 0800 hours). When faced with incidents with these potential risk factors, anaesthetists should consider earlier interventions and request assistance at an earlier stage. Educational strategies on incident prevention and management should place even further emphasis on scenarios involving these factors.

A cross-sectional overview of the first 4,000 incidents reported to webAIRS, a de-identified web-based anaesthesia incident reporting system in Australia and New Zealand.

webAIRS is a web-based de-identified anaesthesia incident reporting system, which was introduced in Australia and New Zealand in September 2009. By July 2016, 4,000 incident reports had been received. The incidents covered a wide range of patient age (<28 days to >90 years), American Society of Anesthesiologists physical status, and body mass index (<18.5 to >50 kg/m2). They occurred across a wide range of anaesthesia techniques and grade of anaesthesia provider, and over a wide range of anaesthetising locations and times of day. In a high proportion the outcome was not benign; about 26% of incidents were associated with patient harm and a further 4% with death. Incidents appeared to be an ever-present risk in anaesthetic practice, with extrapolated estimates exceeding 200 per week across Australia and New Zealand. Independent of outcomes, many anaesthesia incidents were associated with increased use of health resources. The four most common main categories of incident were Respiratory/Airway, Medication, Cardiovascular, and Medical Device/Equipment. Over 50% of incidents were considered preventable. The narratives accompanying each incident provide a rich source of information, which will be analysed in subsequent reports on particular incident types. The summary data in this initial overview are a sober reminder of the prevalence and unpredictability of anaesthesia incidents, and their potential morbidity and mortality. The data justify current efforts to better prevent and manage anaesthesia incidents in Australia and New Zealand, and identify areas in which increased resources or additional initiatives may be required.

Bow-tie diagrams for risk management in anaesthesia.

Bow-tie analysis is a risk analysis and management tool that has been readily adopted into routine practice in many high reliability industries such as engineering, aviation and emergency services. However, it has received little exposure so far in healthcare. Nevertheless, its simplicity, versatility, and pictorial display may have benefits for the analysis of a range of healthcare risks, including complex and multiple risks and their interactions. Bow-tie diagrams are a combination of a fault tree and an event tree, which when combined take the shape of a bow tie. Central to bow-tie methodology is the concept of an undesired or 'Top Event', which occurs if a hazard progresses past all prevention controls. Top Events may also occasionally occur idiosyncratically. Irrespective of the cause of a Top Event, mitigation and recovery controls may influence the outcome. Hence the relationship of hazard to outcome can be viewed in one diagram along with possible causal sequences or accident trajectories. Potential uses for bow-tie diagrams in anaesthesia risk management include improved understanding of anaesthesia hazards and risks, pre-emptive identification of absent or inadequate hazard controls, investigation of clinical incidents, teaching anaesthesia risk management, and demonstrating risk management strategies to third parties when required.

Chewing gum in the preoperative fasting period: an analysis of de-identified incidents reported to webAIRS.

The role of preoperative fasting is well established in current anaesthetic practice with different guidelines for clear fluids and food. However, chewing gum may not be categorised as either food or drink by some patients, and may not always be specified in instructions given to patients about preoperative fasting. The aim of this paper was to review anaesthesia incidents involving gum chewing reported to webAIRS to obtain information on the risks, if any, of gum chewing during the preoperative fasting period. There were nine incidents involving chewing gum reported between late 2009 and early 2015. There were no adverse outcomes from the nine incidents other than postponement of surgery in three cases and cancellation in one. In particular, there were no reports of aspiration or airway obstruction. Nevertheless, there were five cases in which the gum was not detected preoperatively and was found in the patient's mouth either intraoperatively or postoperatively. These cases of undetected gum occurred despite patient and staff compliance with their current preoperative checklists. While the risk of increased gastric secretions related to chewing gum preoperatively are not known, the potential for airway obstruction if the gum is not detected and removed preoperatively is very real. We recommend that patients should be specifically advised to avoid gum chewing once fasting from clear fluids is commenced, and that a specific question regarding the presence of chewing gum should be added to all preoperative checklists.

An audit of the statistical validity of conclusions of clinical superiority in anaesthesia journals.

Making a statistically valid conclusion of the superiority of a clinical intervention in a clinical trial requires not only a statistically significant P value, but also adequate a priori power and an observed effect size larger than the clinically important value specified in the sample size calculation. We scrutinised the five most highly cited clinical trials reporting one or more conclusions of clinical superiority published in Anesthesiology, the British Journal of Anaesthesia, Anaesthesia, Anesthesia and Analgesia and Anaesthesia and Intensive Care in 2011 or 2012 to determine how many met all three requisite criteria. In the 25 articles, there were a total of 36 unconditional conclusions of the superiority of a clinical intervention. All were supported by a statistically significant P value. However, only 15 (41.6%) met all three requisite statistical criteria to support clinical superiority. The remainder included secondary outcomes without specific reference to their observational nature, and primary outcomes whose observed effect size was smaller than the clinically important value specified in the sample size calculation. These findings indicate that clinicians should closely scrutinise conclusions of clinical superiority in anaesthesia journals. Many will be 'hypothesis-generating observations' without adequate statistical support for a conclusion of clinical superiority in their own right.

Measuring the quality of anaesthesia from a patient's perspective: development, validation, and implementation of a short questionnaire.

BACKGROUND: The primary aim of this study was to develop and validate a short psychometric instrument to assess the patient's perception of the quality of anaesthesia. METHODS: In Part 1, the Perception of Quality in Anaesthesia (PQA) questionnaire was developed, pilot tested, and validated. Attributes of high-quality anaesthesia were identified using a process that restricted input to patients and members of the public. In Part 2, patient cohorts completed the PQA before, and after, a 6 month period where anaesthetists were given individualized performance data using questions from the PQA. RESULTS: In Part 1, items in the PQA were identified and ranked by 120 patients and members of the public. Validity and reliability of the PQA was assessed by 714 patients. Principal component analysis showed that the PQA comprised five factors: attention/gentleness; pain management; information/confidence; postoperative nausea or vomiting (PONV); and concerns addressed. In Part 2, there were 2046 patient participants in the pre-feedback cohort, 4251 in the feedback cohort, and 1421 in the post-feedback cohort. Unsatisfactory experience in at least one PQA factor was described by 45.2% [95% confidence interval (CI) 43.1-47.4%] during the pre-feedback period, and 35.0% (95% CI 32.6-37.6%) during the post-feedback period. CONCLUSIONS: We developed and validated a patient-derived questionnaire to measure the patient's perception of anaesthesia quality. PONV, postoperative pain management, and communication with the anaesthetist are the most important features of the patient's experience. Feedback of PQA performance scores to anaesthetists can lead to improved patient experience.

National anaesthesia mortality reporting in Australia from 1985-2008.

This article summarises the Australian national anaesthesia mortality data from 1985-2008, previously published in eight consecutive triennial reports and covering an estimated 50 million anaesthetics. The data were obtained using consistent definitions and methodology over a 24-year period. Anaesthesia-related mortality in Australia fell from about 1:36,000 anaesthetics in the 1985-1987 triennium to about 1:55,000 for the most recent reported 2006-2008 triennium. The percentage of the deaths considered anaesthesia-caused fell from about 50% of all anaesthesia-related deaths in the 1985-1987 triennium to about 15% of all anaesthesia-related deaths in the 2006-2008 triennium. The percentage of anaesthesia-related deaths considered non-preventable (no correctable anaesthetic factor identified) increased from about 4% in the 1991-1993 triennium to about 50% in the 2006-2008 triennium. There was also an increase in the proportion of deaths in which the patient's medical condition was considered a significant factor in the death over this period. While the trends are encouraging, they nevertheless suggest that additional efforts are required to further reduce 'preventable' anaesthetic deaths, and that continuing research and development into safer agents, techniques and approaches are required to reduce the incidence of deaths currently considered 'non-preventable'.