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.

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.

Survival from perioperative anaphylaxis in Western Australia 2000-2009.

BACKGROUND: The mortality from perioperative anaphylaxis has recently been quoted in a range between 3 and 9%. However, it was our impression in Western Australia that we had had no deaths from perioperative anaphylaxis for over a decade. As we have comprehensive processes in place to investigate both perioperative anaphylaxis and anaesthesia-related deaths, we undertook this study to determine our actual perioperative anaphylaxis mortality rate. METHODS: We obtained the number of deaths related to perioperative anaphylaxis for the decade 2000-2009 from the database of the West Australian Anaesthetic Mortality Committee; in Western Australia it is a legal requirement to report all deaths that occur within 48 h of an anaesthetic, and all deaths due to a complication of an anaesthetic. We obtained the number of cases of perioperative anaphylaxis for the same period from the database of the West Australian Anaesthetic Drug Reaction Clinic. RESULTS: From 2000 to 2009, there were 45 anaesthesia-related deaths in Western Australia, but none of these involved anaphylaxis. Over this period, there were 264 cases classified by the West Australian Anaesthetic Drug Reaction Clinic as anaphylaxis. The 95% confidence interval for the observed 0/264 mortality rate is 0-1.4%. There were about three million anaesthetics administered in Western Australia over the decade, giving a perioperative anaphylaxis rate of ~1:11,000. CONCLUSIONS: Our incidence of perioperative anaphylaxis was within expectations, but our mortality rate was lower than recently quoted figures. It is likely that the current true perioperative anaphylaxis mortality rate is within the range 0-1.4%.

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.

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.

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.

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.

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.

Topographical and histological presentation of mammographic pathology in breast cancer.

Between 1979 and 1985 surgical resections from 680 cases of primary breast cancer were examined histologically. The patients were divided into four groups: (i) patients aged between 45 and 69 years who had been screened (n = 316); (ii) those younger than 45 who had not been screened (n = 55); (iii) those aged between 45 and 69 who had not been screened (n = 104); and (iv) those older than 69 who had not been screened (n = 205). The material was compared in terms of the association between in situ and invasive carcinoma. There was a low incidence of lobular carcinoma in situ (LCIS) in all groups and a high incidence of ductal carcinoma in situ (DCIS) which declined with age. Ninety nine group i patients had in situ carcinoma or early invasive carcinoma (less than 1 cm in diameter) compared with 19 of group iii cases. Screened patients had fewer multicentric cancers and a lower incidence of large invasive cancer compared with unscreened patients. Group ii patients had a higher incidence of whole quadrant in situ carcinoma, multiple cancer, and lymph node metastases. Group iv patients had a lower incidence of in situ cancer, and more low grade cancer than the other groups. Cases were divided into four types on the basis of this analysis.

Incidence and significance of argentaffin and paneth cells in some tumours of the large intestine.

The incidence of argentaffin and Paneth cells in epithelial tumours of the large intestine was investigated. Argentaffin cells were found in adenomatous polyps, villus adenomas, polyposis coli, Peutz-Jehgers' polyps, juvenile polyposis, and adenocarcinomas. Paneth cells were not found in metaplastic or juvenile polyps. The crypt unit was destroyed in neoplasia and argentaffin and Paneth cells occurred either as a result of sequestration or were taking part in the neoplastic process. The crypt unit was retained in the disorders of epithelial growth. The identification of argentaffin and Paneth cells enabled the crypt to be defined and thus provided a useful, practical aid in the differentiation between neoplasms and disorders of epithelial growth.

Mucinous cystadenoma and cystadenocarcinoma of the vermiform appendix with particular reference to mucocele and pseudomyxoma peritonei.

Ten cases of mucocele of the vermiform appendix are described. Eight cases were of mucinous cystadenoma of the appendix and six cases showed acute inflammation. Two of the six cases showed pseudoinvasion of the appendix and in a further case the appendix had perforated with extrusion of a misplaced neoplasm. Two cases were of mucinous cystadenocarcinoma and one of these was diagnosed as ;pseudomyxoma peritonei'. ;Pseudomyxoma peritonei' is a misnomer and is caused by dissemination of a mucinous cystadenocarcinoma within the peritoneal cavity. The special problems of histological diagnosis are discussed.

The colon mucus antibody.

One thousand one hundred and thirty sera from hospital patients under investigation for autoimmune disease were tested for colon mucus antibody and tissue antibodies. The sera with a positive mucus antibody were retested against a panel of test colons of known blood group using IgG, IgA, and IgM antihuman globulin fluorescein isothiocyanate conjugate. It was found that there was a variation between the results obtained with different test colons. This was considered to be due to a system in tissues of mucus isoantigens produced by the goblet cells of the colon. Using this panel of test colons raised the percentage of mucus antibodies detected in cases of ulcerative colitis from 14 to 37%. The presence of the mucus antibody was found to be shortlived in some patients. The colon mucus antibody was also found in thyroid disease and chronic asthma and the reasons for this finding are discussed.

Dose-response relationship of atracurium besylate in the halothane-anaesthetised pig.

The dose response relationship for the intermediate-acting non-depolarising muscle relaxant, atracurium besylate in the pig was determined using evoked electromyography. An incremental dose technique was used in seven Large White/Landrace crossbred pigs anaesthetised with nitrous oxide and halothane. ED50 and ED95 were 510 +/- 87 micrograms kg-1 and 1150 +/- 270 micrograms kg-1, respectively. Although these values may represent an overestimate, they provide a reasonable guideline for the use of atracurium by veterinary anaesthetists.

Invasive breast cancer--the tip of an iceberg.

Use of large (6 in. X 4 in.) paraffin sections in the routine examination of specimens from patients with operable breast cancer has revealed multiple quadrant involvement by carcinoma in 20% of 186 consecutive cases. Eighty-nine per cent of patients had invasive carcinomas, which were associated with carcinoma in situ (CIS) in 71%. CIS was frequently extensive, and in 47% was remote from the principal invasive lesion. Fourteen patients had multifocal invasive disease with 34 separate primary tumours. The involvement of 32% of sampled axillary nodes by tumour, combined with this significant incidence of multiple quadrant disease, brings into question the rationale of local surgery in most cases even of early breast cancer. Mastectomy with node sampling permits full assessment of the extent of disease, which is essential for the logical selection of patients for adjuvant therapy. The potential role for limited surgery in non-invasive and very small invasive tumours in combination with radiotherapy remains under evaluation.

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.