The DIFFMASK score for predicting difficult facemask ventilation: a cohort study of 46,804 patients.

Facemask ventilation is an essential part of airway management. Correctly predicting difficulties in facemask ventilation may reduce the risk of morbidity and mortality among patients at risk. We aimed to develop and evaluate a weighted risk score for predicting difficult facemask ventilation during anaesthesia. We analysed a cohort of 46,804 adult patients who were assessed pre-operatively airway for 13 predictors of difficult airway management and subsequently underwent facemask ventilation during general anaesthesia. We developed the Difficult Facemask (DIFFMASK) score in two consecutive steps: first, a multivariate regression analysis was performed; and second, the regression coefficients of the adjusted regression model were converted into a clinically applicable weighted point score. The predictive accuracy of the DIFFMASK score was evaluated by assessment of receiver operating characteristic curves. The prevalence of difficult facemask ventilation was 1.06% (95%CI 0.97-1.16). Following conversion of regression coefficients into 0, 1, 2 or 3 points, the cumulated DIFFMASK score ranged from 0 to 18 points and the area under the receiver operating characteristic curve was 0.82. The Youden index indicated a sum score ≥ 5 as an optimal cut-off value for prediction of difficult facemask ventilation giving a sensitivity of 85% and specificity of 59%. The DIFFMASK score indicated that a score of 6-10 points represents a population of patients who may require heightened attention when facemask ventilation is planned, compared with those patients who are obviously at a high- or low risk of difficulties. The DIFFMASK score may be useful in a clinical context but external, prospective validation is needed.

Characteristics of children aged 2-17 years undergoing anaesthesia in Danish hospitals 2005-2015: a national observational study.

Provision of paediatric anaesthesia requires careful consideration of the child's cognitive state, unique body composition and physiology. In an observational cohort study, we describe the population characteristics and conduct of anaesthesia in children aged 2-17 years from 1 January 2005 to 31 December 2015. Children were identified from the Danish Anaesthesia Database. We recorded the following variables: age; sex; comorbidities; indications for anaesthesia; practice of anaesthesia; and complications. Results are presented for two age groups: 2-5 and 6-17 years. In total, 32,840 (61% male) children aged 2-5 years received 50,484 anaesthesia episodes and 91,418 (54% male) children aged 6-17 years received 141,082 anaesthesia episodes. The younger children, compared with the older children, were more frequently anaesthetised at a university hospital (50% vs. 36%) and for non-surgical procedures (24% vs. 8%). For both age groups, general anaesthesia was the primary choice of anaesthesia regardless of the reason for anaesthesia. For surgery, general anaesthesia using inhalational agents in addition to intravenous agents or alone was more frequently used in younger children (49% vs. 15%), whereas older children commonly received total intravenous anaesthesia (50% vs. 83%). Regional anaesthesia was infrequently utilised. Complications occurred in 3.3% of anaesthesia episodes among 2-5 year olds compared with 3.7% of anaesthesia episodes among children aged 6-17 years. In conclusion, we found younger children (aged 2-5), compared with older children (aged 6-17) were more frequently anaesthetised for non-surgical reasons, at a university hospital and using inhalational agents. Complications were rare.

Volume of ropivacaine 0.2% and common peroneal nerve block duration: a randomised, double-blind cohort trial in healthy volunteers.

The volume-duration relationship using low concentrations of ropivacaine for peripheral nerve blocks is unknown, even though low concentrations of ropivacaine are increasingly used clinically. We investigated the effect of ropivacaine 0.2% on common peroneal nerve block duration. With ethical committee approval, 60 consenting, healthy volunteers were randomly allocated to receive one of five volumes of ropivacaine 0.2% (2.5, 5.0, 10, 15 or 20 ml) administered by ultrasound-guided, catheter-based injection (at 10 ml.min-1 ) near the common peroneal nerve. Our primary outcome was duration of sensory block, defined by insensitivity to a cold stimulus. Our secondary outcome was duration of motor block. Outcomes were assessed every hour from onset of block to complete remission. Intergroup differences were tested using one-way ANOVA followed by regression analyses using the 20 ml intervention group as reference. Block durations varied significantly (p < 0.0001) between groups. Mean (SD) sensory block durations were 9.2 (3.3), 12.5 (3.0), 15.5 (4.4), 17.3 (3.5) and 17.3 (4.6) h. Mean (SD) motor block durations were 3.3 (2.1), 7.2 (2.5), 9.2 (2.2), 12.7 (2.5) and 12.5 (2.5) h. Regression analysis showed that the effect of volume on block duration was progressively smaller with increasing volume, reaching a threshold volume above which there was no effect on nerve block duration (10 ml for sensory block and 15 ml for motor block). We conclude that there is a ceiling effect of increasing volume of ropivacaine 0.2% on both sensory and motor block duration of the common peroneal nerve.

Effect of a lateral infraclavicular brachial plexus block on the axillary and suprascapular nerves as determined by electromyography - a cohort study.

We aimed to examine to what extent a lateral infraclavicular brachial plexus block affected the axillary and the suprascapular nerve. We included patients undergoing hand surgery anaesthetised with a lateral infraclavicular brachial plexus block. Our primary outcome was the relative change in surface electromyography during maximum voluntary isometric contraction of the medial deltoid muscle (axillary nerve) and the infraspinatus muscle (suprascapular nerve) from baseline to 30 min after the block procedure. A reduction in electromyography of > 50% defined a successful block. The impact of the block on the shoulder nerves was compared with the surgical target nerves of the arm and hand (musculocutaneous, radial, median and ulnar nerves). Twenty patients were included. The medians of the relative changes in the surface electromyography were significantly reduced (both p < 0.001) with 92% for the deltoid muscle and 30% for the infraspinatus muscle, respectively. In total, 18 out of 20 patients had reductions > 50% for the deltoid muscle, which was significantly different from the infraspinatus muscle, where the proportion was 5 out of 20 (p < 0.001). The medians of the relative reductions in electromyography for the arm and hand muscles were 90-96%, similar to the effect on the deltoid muscle. Our results suggest that a lateral infraclavicular block provides block of the axillary nerve comparable to the block of the surgical target nerves. The suprascapular nerve is blocked to a lesser degree. Combining a lateral infraclavicular brachial plexus block with a selective suprascapular block for shoulder surgery warrants further studies.

Effects of avoidance or use of neuromuscular blocking agents on outcomes in tracheal intubation: a Cochrane systematic review.

Cohort studies have indicated that avoidance of neuromuscular blocking agents (NMBA) is a risk factor for difficult tracheal intubation. However, the impact of avoiding NMBA on tracheal intubation, possible adverse effects, and postoperative discomfort has not been evaluated in a systematic review of randomised trials. We searched several databases for trials published until January 2017. We included randomised controlled trials comparing the effect of avoiding vs using NMBA. Two independent authors assessed risk of bias and extracted data. The risk of random errors was assessed by trial sequential analysis (TSA). We included 34 trials (3565 participants). In the four trials judged to have low risk of bias, there was an increased risk of difficult tracheal intubation with no use of NMBA [random-effects model, risk ratio (RR) 13.27, 95% confidence interval (CI) 8.19-21.49, P<0.00001, TSA-adjusted CI 1.85-95.04]. The result was confirmed when including all trials, (RR 5.00, 95% CI 3.49-7.15, P<0.00001, TSA-adjusted CI 1.20-20.77). There was a significant risk of upper airway discomfort or injury by avoiding NMBA (RR=1.37, 95% CI 1.09-1.74, P=0.008, TSA-adjusted CI 1.00-1.86). None of the trials reported mortality. Avoiding NMBA was significantly associated with difficult laryngoscopy, (RR 2.54, 95% CI 1.53-4.21, P=0.0003, TSA-adjusted CI 0.27-21.75). In a clinical context, one must balance arguments for using NMBA when performing tracheal intubation.

Characteristics of children less than 2 years of age undergoing anaesthesia in Denmark 2005-2015: a national observational study.

There are few data available that describe the current anaesthetic management of children. We have analysed anaesthetic practice and peri-operative complications for children in Denmark aged less than two years. We conducted a population-based observational cohort study using the Danish Anaesthesia Database to identify children who received anaesthesia in hospital from 1 January 2005 until 31 December 2015. Data were combined with that from the Danish National Patient Registry and the Danish Civil Registration System. Age, sex, height, weight, ASA physical status, days in hospital before anaesthesia, number of anaesthetics per child, indications for anaesthesia, methods of anaesthesia, airway management and complications were all recorded. A total of 17,436 children (64% of whom were male) received 27,653 anaesthetics during the study period. In 58% of cases, the child had an ASA physical status score of 1. Thirty-seven percent had a previous anaesthetic episode. Seventy-nine percent were anaesthetised at a university hospital. The indications for anaesthesia were surgery (70%), diagnostic radiology (16%), non-surgical care (11%) and other indications (3%). General anaesthesia combining intravenous and inhalational agents was the most common approach for surgery (68%) and diagnostic radiology (47%). For non-surgical care, general anaesthesia using inhalational agents was the most common method (42%). Neuraxial blocks were used infrequently. The most common regional anaesthetic nerve block was an infraclavicular brachial plexus block (11%). Peri-operative complications occurred in 1.71% of cases. A large proportion of anaesthetics were conducted in children with comorbidities. Non-surgical indications for anaesthesia were frequent and peri-operative complications were rare.

Initial placement and secondary displacement of a new suture-method catheter for sciatic nerve block in healthy volunteers: a randomised, double-blind pilot study.

We performed a randomised double-blind pilot study in 16 healthy volunteers to investigate the success rate for placing a new suture-method catheter for sciatic nerve block. A catheter was inserted into both legs of volunteers and each was randomly allocated to receive 15 ml lidocaine 2% through the catheter in one leg and 15 ml saline in the other leg. Successful placement of the catheter was defined as a 20% decrease in maximum voluntary isometric contraction for dorsiflexion of the ankle. Secondary outcomes were maximum voluntary isometric contraction for plantar flexion at the ankle, surface electromyography and cold sensation. After return of motor and sensory function, volunteers performed standardised physical exercises; injection of the same study medication was repeated in the same leg and followed by motor and sensory assessments. Fifteen of 16 (94%; 95%CI 72-99%) initial catheter placements were successful. The reduction in maximum voluntary isometric contraction and surface electromyography affected the peroneal nerve more often than the tibial nerve. Eleven of 15 (73%; 95%CI 54-96%) catheters remained functional with motor and sensory block after physical exercise, and the maximal displacement was 5 mm. Catheters with secondary block failure were displaced between 6 and 10 mm. One catheter was displaced 1.8 mm that resulted in a decrease in maximum voluntary isometric contraction of less than 20%. After repeat test injection, 14 of the 16 volunteers had loss of cold sensation. Neither motor nor sensory functions were affected in the legs injected with placebo. We conclude that the suture-method catheter can be placed with a high success rate, but that physical exercise may cause displacement.

Prediction of difficult mask ventilation using a systematic assessment of risk factors vs. existing practice - a cluster randomised clinical trial in 94,006 patients.

We compared implementation of systematic airway assessment with existing practice of airway assessment on prediction of difficult mask ventilation. Twenty-six departments were cluster-randomised to assess eleven risk factors for difficult airway management (intervention) or to continue with their existing airway assessment (control). In both groups, patients predicted as a difficult mask ventilation and/or difficult intubation were registered in the Danish Anaesthesia Database, with a notational summary of airway management. The trial's primary outcome was the respective incidence of unpredicted difficult and easy mask ventilation in the two groups. Among 94,006 patients undergoing mask ventilation, the incidence of unpredicted difficult mask ventilation in the intervention group was 0.91% and 0.88% in the control group; (OR) 0.98 (95% CI 0.66-1.44), p = 0.90. The incidence of patients predicted difficult to mask ventilate, but in fact found to be easy ('falsely predicted difficult') was 0.64% vs. 0.35% (intervention vs. control); OR 1.56 (1.01-2.42), p = 0.045. In the intervention group, 86.3% of all difficult mask ventilations were not predicted, compared with a higher proportion 91.2% in the control group, OR 0.61 (0.41-0.91), p = 0.016. The systematic intervention did not alter the overall incidence of unpredicted difficult mask ventilations, but of the patients who were found to be difficult to mask ventilate, the proportion predicted was higher in the intervention group than in the control group. However, this was at a 'cost' of increasing the number of mask ventilations falsely predicted to be difficult.

Emergency surgical airway management in Denmark: a cohort study of 452 461 patients registered in the Danish Anaesthesia Database.

BACKGROUND: The emergency surgical airway (ESA) is the final option in difficult airway management. We identified ESA procedures registered in the Danish Anaesthesia Database (DAD) and described the performed airway management. METHODS: We extracted a cohort of 452 461 adult patients undergoing general anaesthesia and tracheal intubation from the DAD from June 1, 2008 to March 15, 2014. Difficult airway management involving an ESA was retrieved for analysis and compared with hospitals files. Two independent reviewers evaluated airway management according to the ASAs'2003 practice guideline for difficult airway management. RESULTS: In the DAD cohort 27 out of 452 461 patients had an ESA representing an incidence of 0.06 events per thousand (95% CI; 0.04 to 0.08). A total of 12 149/452 461 patients underwent Ear-Nose and Throat (ENT) surgery, giving an ESA incidence among ENT patients of 1.6 events per thousand (95% CI; 1.0-2.4). A Supraglottic Airway Device and/or the administration of a neuromuscular blocking agent before ESA were used as a rescue in 6/27 and 13/27 of the patients, respectively. In 19/27 patients ENT surgeons performed the ESA's and anaesthetists attempted 6/27 of the ESAs of which three failed. Reviewers evaluated airway management as satisfactory in 10/27 patients. CONCLUSIONS: The incidence of ESA in the DAD cohort was 0.06 events per thousand. Among ENT patients, the ESA Incidence was 1.6 events per thousand. Airway management was evaluated as satisfactory for 10/27 of the patients. ESA performed by anaesthetists failed in half of the patients.

Effects of using the simplified airway risk index vs usual airway assessment on unanticipated difficult tracheal intubation - a cluster randomized trial with 64,273 participants.

BACKGROUND: Unanticipated difficult intubation remains a challenge in anaesthesia. The Simplified Airway Risk Index (SARI) is a multivariable risk model consisting of seven independent risk factors for difficult intubation. Our aim was to compare preoperative airway assessment based on the SARI with usual airway assessment. METHODS: From 01.10.2012 to 31.12.2013, 28 departments were cluster-randomized to apply the SARI model or usual airway assessment. The SARI group implemented the SARI model. The Non-SARI group continued usual airway assessment, thus reflecting a group of anaesthetists' heterogeneous individual airway assessments. Preoperative prediction of difficult intubation and actual intubation difficulties were registered in the Danish Anaesthesia Database for both groups. Patients who were preoperatively scheduled for intubation by advanced techniques (e.g. video laryngoscopy; flexible optic scope) were excluded from the primary analysis. Primary outcomes were the proportions of unanticipated difficult and unanticipated easy intubation. RESULTS: A total of 26 departments (15 SARI and 11 Non-SARI) and 64 273 participants were included. In the primary analyses 29 209 SARI and 30 305 Non-SARI participants were included.In SARI departments 2.4% (696) of the participants had an unanticipated difficult intubation vs 2.4% (723) in Non-SARI departments. Odds ratio (OR) adjusted for design variables was 1.03 (95% CI: 0.77-1.38). The proportion of unanticipated easy intubation was 1.42% (415) in SARI departments vs 1.00% (302) in Non-SARI departments. Adjusted OR was 1.26 (0.68-2.34). CONCLUSIONS: Using the SARI compared with usual airway assessment we detected no statistical significant changes in unanticipated difficult- or easy intubations. CLINICAL TRIAL REGISTRATION: NCT01718561.

Anaesthesia care with and without tracheal intubation during emergency endoscopy for peptic ulcer bleeding: a population-based cohort study.

BACKGROUND: Emergency upper gastrointestinal bleeding is a common condition with high mortality. Most patients undergo oesophagogastroduodenoscopy (OGD), but no universally agreed approach exists to the type of airway management required during the procedure. We aimed to compare anaesthesia care with tracheal intubation (TI group) and without airway instrumentation (monitored anaesthesia care, MAC group) during emergency OGD. METHODS: This was a prospective, nationwide, population-based cohort study during 2006-13. Emergency OGDs performed under anaesthesia care were included. End points were 90 day mortality (primary) and length of stay in hospital (secondary). Associations between exposure and outcomes were assessed in logistic and linear regression models, adjusted for the following potential confounders: shock at admission, level of anaesthetic expertise present, ASA score, Charlson comorbidity index score, BMI, age, sex, alcohol use, referral origin (home or in-hospital), Forrest classification, ulcer localization, and postoperative care. RESULTS: The study group comprised 3580 patients under anaesthesia care: 2101 (59%) for the TI group and 1479 (41%) for the MAC group. During the first 90 days after OGD, 18.9% in the TI group and 18.4% in the MAC group died, crude odds ratio=1.03 [95% confidence interval (CI)=0.87-1.23, P=0.701], adjusted odds ratio=0.95 (95% CI=0.79-1.15, P=0.590). Patients in the TI group stayed slightly longer in hospital [mean 8.16 (95% CI=7.63-8.60) vs 7.63 days (95%=CI 6.92-8.33), P=0.108 in adjusted analysis]. CONCLUSIONS: In this large population-based cohort study, anaesthesia care with TI was not different from anaesthesia care without airway instrumentation in patients undergoing emergency OGD in terms of 90 day mortality and length of hospital stay.

Peripheral venous lactate at admission is associated with in-hospital mortality, a prospective cohort study.

BACKGROUND: The prognostic value of blood lactate as a predictor of adverse outcome in the acutely ill patient is unclear. The aim of this study was to investigate if a peripheral venous lactate measurement, taken at admission, is associated with in-hospital mortality in acutely ill patients with all diagnosis. Furthermore, we wanted to investigate if the test improves a triage model in terms of predicting in-hospital mortality. METHODS: We retrieved a cohort of 2272 adult patients from a prospectively gathered acute admission database. We performed regression analysis to evaluate the association between the relevant covariates and the outcome measure: in-hospital mortality. RESULTS: Lactate as a continuous variable was a risk for in-hospital mortality with an odds ratio (OR) of 1.40 [95% confidence interval (CI) 1.25-1.57, P<0.0001]. OR for in-hospital mortality increased with increasing lactate levels from 2.97 (95% CI 1.55-5.72, P<0.001) for lactate between 2 mmol/l and 4 mmol/l, to 7.77 (95% CI 3.23-18.66, P<0.0001) for lactate>4 mmol/l. If the condition was non-compensated (i.e. pH<7.35), OR for in-hospital mortality increased to 19.99 (7.26-55.06, P<0.0001). Patient with a blood lactate at 4 mmol/l or more had a risk of in-hospital mortality equivalent to the patients in the most urgent triage category. CONCLUSION: We found elevated admission peripheral venous lactate to be independently associated with in-hospital mortality in the acutely ill patient admitted to the emergency department. Patients with a lactate>4 mmol/l at hospital admission should be considered triaged to the most urgent triage category.

A novel suture method to place and adjust peripheral nerve catheters.

We have developed a peripheral nerve catheter, attached to a needle, which works like an adjustable suture. We used in-plane ultrasound guidance to place 45 catheters close to the femoral, saphenous, sciatic and distal tibial nerves in cadaver legs. We displaced catheters after their initial placement and then attempted to return them to their original positions. We used ultrasound to evaluate the initial and secondary catheter placements and the spread of injectate around the nerves. In 10 cases, we confirmed catheter position by magnetic resonance imaging. We judged 43/45 initial placements successful and 42/43 secondary placements successful by ultrasound, confirmed in 10/10 cases by magnetic resonance imaging.

Diagnostic accuracy of anaesthesiologists' prediction of difficult airway management in daily clinical practice: a cohort study of 188 064 patients registered in the Danish Anaesthesia Database.

Both the American Society of Anesthesiologists and the UK NAP4 project recommend that an unspecified pre-operative airway assessment be made. However, the choice of assessment is ultimately at the discretion of the individual anaesthesiologist. We retrieved a cohort of 188 064 cases from the Danish Anaesthesia Database, and investigated the diagnostic accuracy of the anaesthesiologists' predictions of difficult tracheal intubation and difficult mask ventilation. Of 3391 difficult intubations, 3154 (93%) were unanticipated. When difficult intubation was anticipated, 229 of 929 (25%) had an actual difficult intubation. Likewise, difficult mask ventilation was unanticipated in 808 of 857 (94%) cases, and when anticipated (218 cases), difficult mask ventilation actually occurred in 49 (22%) cases. We present a previously unpublished estimate of the accuracy of anaesthesiologists' prediction of airway management difficulties in daily routine practice. Prediction of airway difficulties remains a challenging task, and our results underline the importance of being constantly prepared for unexpected difficulties.

Ultrasound-guided lateral infraclavicular block evaluated by infrared thermography and distal skin temperature.

BACKGROUND: Brachial plexus blocks cause changes in hand and digit skin temperature. We investigated thermographic patterns after the lateral infraclavicular brachial plexus block. We hypothesised that a successful lateral infraclavicular block could be predicted by increased skin temperature of the 2nd and 5th digits. METHODS: We performed an ultrasound-guided lateral infraclavicular block in 45 patients undergoing upper limb surgery. The contralateral hand served as control and we obtained infrared thermographic images of both hands before the block and during the following 30 min. We defined areas of interest on the hands and analysed mean skin temperature of each area. RESULTS: Forty patients completed the study. Thirty blocks were successful, six were failures and four were partial failures. Four distinct patterns of skin temperature changes were revealed with highly significant changes in temperature, depending on block success. A simultaneous 1 °C ipsilateral increase in skin temperature of the 2nd and 5th digits predicted a successful block with a positive predictive value of 100%. A 5 °C difference in digit skin temperature compared with the contralateral hand had a positive predictive value of 96%, and a digit skin temperature ≤ 30 °C 30 min after performing the block had a predictive value of 100% for a failed block. CONCLUSIONS: Four different thermographic patterns were found. Simultaneous increases in skin temperature of both the 2nd and 5th digits predicted lateral infraclavicular block success with a positive predictive value of 100%. Digit skin temperature ≤ 30 °C 30 min after performing the block indicated block failure.

Mortality and postoperative care pathways after emergency gastrointestinal surgery in 2904 patients: a population-based cohort study.

BACKGROUND: Emergency major gastrointestinal (GI) surgery carries a considerable risk of mortality and postoperative complications. Effective management of complications and appropriate organization of postoperative care may improve outcome. The importance of the latter is poorly described in emergency GI surgical patients. We aimed to present mortality data and evaluate the postoperative care pathways used after emergency GI surgery. METHODS: A population-based cohort study with prospectively collected data from six Capital Region hospitals in Denmark. We included 2904 patients undergoing major GI laparotomy or laparoscopy surgery between January 1, 2009, and December 31, 2010. The primary outcome measure was 30 day mortality. RESULTS: A total of 538 patients [18.5%, 95% confidence interval (CI): 17.1-19.9] died within 30 days of surgery. In all, 84.2% of the patients were treated after operation in the standard ward, with a 30 day mortality of 14.3%, and 4.8% were admitted to the intensive care unit (ICU) after a median stay of 2 days (inter-quartile range: 1-6). When compared with 'admission to standard ward', 'admission to standard ward before ICU admission' and 'ICU admission after surgery' were independently associated with 30 day mortality; odds ratio 5.45 (95% CI: 3.48-8.56) and 3.27 (95% CI: 2.45-4.36), respectively. CONCLUSIONS: Mortality in emergency major GI surgical patients remains high. Failure to allocate patients to the appropriate level of care immediately after surgery may contribute to the high postoperative mortality. Future research should focus on improving risk stratification and evaluating the effect of different postoperative care pathways in emergency GI surgery.

Ultrasound-guided block of the axillary nerve: a case series of potential clinical applications.

The specific blocking of the axillary nerve has never been investigated clinically. We present four cases illustrating potential applications of the axillary nerve block in the perioperative setting and discuss possible directions for future research in this area. The axillary nerve blocks were all performed using a newly developed in-plane ultrasound-guided technique. In one patient undergoing arthroscopic shoulder surgery, we used the axillary nerve block as the only analgesic combined with propofol sedation and spontaneous breathing. Chronic shoulder pain was eliminated after the axillary nerve block in two patients. The pain score after arthroscopic shoulder surgery in these two patients remained low until termination of the nerve block. In a fourth patient, severe post-operative pain after osteosynthesis of a displaced proximal humerus fracture was almost eliminated after performing an axillary nerve block. These findings warrant larger clinical trials that investigate the pain-mediating role of the axillary nerve in the perioperative setting.