New guidelines for research in airway device evaluation: time for an updated approach (ADEPT-2) to the Difficult Airway Society's 'ADEPT' strategy?

In this article we present the learning from a clinical study of airway device evaluation, conducted under the framework of the Difficult Airway Society (DAS, UK) 'ADEPT' (airway device evaluation project team) strategy. We recommend a change in emphasis from small scale randomised controlled trials conducted as research, to larger-scale observational, post-marketing evaluation audits as a way of obtaining more meaningful information.

The lure of the Lüer connector: Non-Lüer connectors in regional anaesthesia.

Health service professionals do not have perfect vigilance. There will always be the possibility that a serious untoward incident can occur due to crossover injections of medication being administered via the wrong route. The universality of the Lüer connector made it very easy to connect several medical devices for different therapeutic uses. Although this was considered a bonus, it also showed the downside as a string of incidents, leading to permanent harm and even death, occurred, warranting actions to prevent the chance of misconnections and wrong-route injections. The International Organisation for Standardisation introduced specific ISO 80 369 connectors for use in different medical systems, with the ISO 80369-6 series of standards specifically designed to improve safety in regional anaesthesia. Human error can never be completely eliminated, but the risk of a patient inadvertently suffering from an inadvertent wrong-route injection can be reduced through the use of new 'fit and no-fit' technology. This article focuses on the universality of the Lüer connector and the introduction of the newly engineered non-Lüer connectors, for specific use in medical systems.

Baseline parameters for rotational thromboelastometry in healthy labouring women: a prospective observational study.

OBJECTIVE: The aim of this study was to establish rotational thromboelastometry (ROTEM® ) baseline parameters in labouring women at term gestation. The secondary aim was to compare these reference ranges with those from previous studies on labouring women and from the manufacturer. DESIGN: A prospective, observational study. SETTING: Tertiary referral hospital. PARTICIPANTS: Healthy women in labour. METHODS: Ethics approval was granted for an opt-out recruitment approach. ROTEM® testing was performed in labouring women at term gestation. Women with any condition affecting coagulation were excluded. ROTEM® Delta reference ranges were derived by calculating the 2.5% and 97.5% centiles for INTEM/EXTEM/FIBTEM parameters including amplitude at 5 minutes (A5), coagulation time (CT) and maximum clot firmness (MCF). MAIN OUTCOME MEASURES: ROTEM® parameters were measured in labouring women before delivery. The following tests were performed: FIBTEM, EXTEM and INTEM. RESULTS: One hundred and twenty-one women met the inclusion criteria, with a mean (± SD) age of 29.6 ± 5.4 years and median (interquartile range) gestation of 39.4 weeks (37.4-40.4 weeks). Seventy-five (62.0%) women were nulliparous and 71 (58.7%) delivered vaginally. The median and interquartile ranges for selected ROTEM® parameters were: FIBTEM A5, 21 mm (IQR 18-23 mm); EXTEM A5, 55 mm (52-58 mm); and EXTEM CT, 52 seconds (48-56 seconds). CONCLUSIONS: The FIBTEM/EXTEM/INTEM amplitudes were higher than the manufacturer's reference ranges for non-obstetric patients. The FIBTEM MCF upper and lower limits were higher and the EXTEM/INTEM CT was shorter and narrower in range. This study provides reference ranges for ROTEM® values in healthy labouring women at term gestation with uncomplicated pregnancies. TWEETABLE ABSTRACT: This is the first study to report on ROTEM® reference ranges with over 120 healthy labouring women of normal weight at term gestation.

Baseline parameters for rotational thromboelastometry (ROTEM®) in healthy pregnant Australian women: a comparison of labouring and non-labouring women at term.

BACKGROUND: Rotational thromboelastometry (ROTEM®) is a point-of-care coagulation test. Reference ranges in non-labouring women have recently been established from a cohort of women presenting for elective caesarean delivery using the recommended minimum sample size of 120. This study aimed to present baseline parameters for labouring and non-labouring women and to compare the mean values of these ROTEM® parameters. METHODS: Ethical approval was granted for an opt-out recruitment approach for labouring women and written consent was obtained from non-labouring women (data published previously). ROTEM® testing was performed in these two cohorts at term gestation. Women with any condition affecting coagulation were excluded. ROTEM® Delta reference ranges were derived by calculating the 2.5 and 97.5 percentiles for INTEM/EXTEM/FIBTEM amplitude at 5 min (A5), coagulation time (CT), maximum clot firmness (MCF) and clot formation time (CFT). RESULTS: One hundred and twenty-one labouring and 132 non-labouring women met inclusion criteria. The mean values for selected ROTEM® parameters for labouring and non-labouring women respectively were: FIBTEM A5, 21.05 and 19.7 mm (P=0.008); EXTEM A5, 54.8 and 53.2 mm (P=0.025); and EXTEM CT, 52.2 and 53.7 s (P=0.049). Significant differences between the groups were observed in measures of clotting onset and clot firmness. CONCLUSIONS: We demonstrated a significant decrease in the mean time-to-clotting onset in labouring women compared with non-labouring women. Mean values for measures of clot firmness were greater in labouring women. In comparison to previously established ROTEM® baseline parameters for non-labouring women, this study provides evidence that there is greater hyper-coagulability in labouring women.

Baseline parameters for rotational thromboelastometry (ROTEM®) in healthy women undergoing elective caesarean delivery: a prospective observational study in Australia.

BACKGROUND: Formal reference ranges for rotational thromboelastometry (ROTEM®) in pregnancy have not been obtained in the recommended minimum sample size of 120. This prospective observational study aimed to establish baseline parameters in an Australian population of women undergoing elective caesarean delivery. The secondary aim was to compare these reference ranges with those from prior studies and the manufacturer. METHODS: Women undergoing elective caesarean delivery at term were included if they were at term, of normal body mass index and had no conditions affecting coagulation. ROTEM® reference ranges were derived by calculating the 2.5 and 97.5 percentiles for INTEM/EXTEM/FIBTEM amplitude at 5 minutes (A5), amplitude at 15 minutes (A15), coagulation time (CT), maximum clot firmness (MCF), and clot formation time (CFT). RESULTS: Of 202 women screened, 132 met the inclusion criteria, having a mean age of 32.7 ±â€¯5.0 years and median body mass index of 23.8 kg/m2 (interquartile range 21.5-26.4). The reference ranges for selected ROTEM® parameters were as follows: FIBTEM A5 (13-28 mm), FIBTEM CT (40-74 s), FIBTEM MCF (16-34 mm), EXTEM A5 (39-66 mm), EXTEM CT (43-69 s), INTEM A5 (38-63 mm). CONCLUSIONS: ROTEM® reference ranges for women with uncomplicated term pregnancies were reported as per the International Federation of Clinical Chemistry. The FIBTEM MCF and FIBTEM/EXTEM/INTEM amplitudes were higher in comparison to the manufacturer's reference ranges for the non-obstetric population. The EXTEM CT was shorter than the non-obstetric reference ranges. These ranges show an increase in coagulability during normal pregnancy compared to the non-pregnant reference ranges.

Increasing body mass index and abdominal subcutaneous fat thickness are associated with increased skin-to-epidural space distance in pregnant women.

BACKGROUND: Body mass index does not indicate the distribution of adipose tissue. Central adiposity may be measured using ultrasound measurement of subcutaneous fat thickness. This study determined if the abdominal subcutaneous fat thickness measured correlated with skin-to-epidural space distance at delivery, and compared this with the booking body mass index. METHODS: We analysed a sub-set of participants from a single-centre, prospective cohort study that assessed the relationship between subcutaneous fat thickness and maternity outcomes. Abdominal subcutaneous fat thickness measurements were obtained during the routine fetal anomaly scan. The skin-to-epidural space distance was obtained in those having epidural or combined spinal-epidural analgesia. Linear regression was used to test for strength of association and adjusted R2 values calculated to determine if subcutaneous fat thickness or body mass index was more strongly associated with skin-to-epidural space distance. RESULTS: The 463 women had a median (IQR) booking body mass index of 25.0 kg/m2 (21.8-29.3) and subcutaneous fat thickness of 16.2 mm (13.0-21.0). The median (IQR) skin-to-epidural space distance was 5.0 cm (4.5-6.0). Both parameters significantly correlated with skin-to-epidural space distance (r=0.53 and 0.68 respectively, P <0.001). Adjusted linear regression coefficient (95% CI) for subcutaneous fat thickness was 0.09 (0.08 to 0.11), R2=0.30 and for body mass index 0.12 (0.11 to 0.13), R2=0.47. CONCLUSIONS: Booking body mass index had a stronger relationship with skin-to- epidural space distance at delivery than subcutaneous fat thickness, explaining 47% of the variation in the skin-to-epidural distance.

Epidural extension failure in obese women is comparable to that of non-obese women.

BACKGROUND: Management of labor epidurals in obese women is difficult and extension to surgical anesthesia is not always successful. Our previous retrospective pilot study found epidural extension was more likely to fail in obese women. This study used a prospective cohort to compare the failure rate of epidural extension in obese and non-obese women and to identify risk factors for extension failure. METHODS: One hundred obese participants (Group O, body mass index ≥ 40 kg/m2 ) were prospectively identified and allocated two sequential controls (Group C, body mass index ≤ 30 kg/m2 ). All subjects utilized epidural labor analgesia and subsequently required anesthesia for cesarean section. The primary outcome measure was failure of the labor epidural to be used as the primary anesthetic technique. Risk factors for extension failure were identified using Chi-squared and logistic regression. RESULTS: The odds ratio (OR) of extension failure was 1.69 in Group O (20% vs. 13%; 95% CI: 0.88-3.21, P = 0.11). Risk factors for failure in obese women included ineffective labor analgesia requiring anesthesiologist intervention, (OR 3.94, 95% CI: 1.16-13.45, P = 0.028) and BMI > 50 kg/m2 (OR 3.42, 95% CI: 1.07-10.96, P = 0.038). CONCLUSION: The failure rate of epidural extension did not differ significantly between the groups. Further research is needed to determine the influence of body mass index > 50 kg/m2 on epidural extension for cesarean section.

Videolaryngoscopy vs. direct laryngoscopy use by experienced anaesthetists in patients with known difficult airways: a systematic review and meta-analysis.

Experienced anaesthetists can be confronted with difficult or failed tracheal intubations. We performed a systematic review and meta-analysis to ascertain if the literature indicated if videolaryngoscopy conferred an advantage when used by experienced anaesthetists managing patients with a known difficult airway. We searched PubMed, MEDLINE, Embase and the Cochrane central register of controlled trials up to 1 January 2017. Outcome parameters extracted from studies were: first-attempt success of tracheal intubation; time to successful intubation; number of intubation attempts; Cormack and Lehane grade; use of airway adjuncts (e.g. stylet, gum elastic bougie); and complications (e.g. mucosal and dental trauma). Nine studies, including 1329 patients, fulfilled the inclusion criteria. First-attempt success was greater for all videolaryngoscopes (OR 0.34 (95%CI 0.18-0.66); p = 0.001). Use of videolaryngoscopy was associated with a significantly better view of the glottis (Cormack and Lehane grades 1 and 2 vs. 3-4, OR 0.04 (95%CI 0.01-0.15); p < 0.00001). Mucosal trauma occurred less with the use of videolaryngoscopy (OR 0.16 (95%CI 0.04-0.75); p = 0.02). Videolaryngoscopy has added value for the experienced anaesthetist, improving first-time success, the view of the glottis and reducing mucosal trauma.

Tracheal extubation of the adult intensive care patient with a predicted difficult airway - a narrative review.

Management of the difficult airway is an important, but as yet poorly-studied, component of intensive care management. Although there has been a strong emphasis on prediction and intubation of the difficult airway, safe extubation of the patient with a potentially difficult airway has not received the same attention. Extubation is a particularly vulnerable time for the critically ill patient and, because of the risks involved and the consequences of failure, it warrants specific consideration. The Royal College of Anaesthetists 4th National Audit Project highlighted differences in the incidence and consequences of major complications during airway management between the operating room and the critical care environment. The findings in the section on Intensive Care and Emergency Medicine reinforce the importance of good airway management in the critical care environment and, in particular, the need for appropriate guidelines to improve patient safety. This narrative review focuses on strategies for safe extubation of the trachea for patients with potentially difficult upper airway problems in the intensive care unit.