Major complications of airway management: a prospective multicentre observational study

We conducted an observational study of serious airway complications, using similar methods to the fourth UK National Audit Project (NAP4) over a period of 1 year across four hospitals in one region in the UK. We also conducted an activity survey over a week, using NAP4 methods to yield an estimate for relevant denominators to help interpret the primary data. There were 17 serious airway complications, defined as: failed airway management leading to cancellation of surgery (eight); airway management in recovery (five); unplanned intensive care admission (three); and unplanned emergency front of neck access (one). There were no reports of death or brain damage. This was an estimate of 0.028% (1 in 3600) complications using the denominator of 61,000 general anaesthetics per year in the region. Complications in patients with ‘predicted easy’ airways were rare (approximately 1 in 14,200), but 45 times more common in those with ‘predicted difficult’ airways (approximately 1 in 315). Airway management in both groups was similar (induction of anaesthesia followed by supraglottic airway or tracheal tube). Use of awake/sedation intubation, videolaryngoscopy and high-flow nasal oxygenation were uncommon even in the predicted difficult airway patients (in 2.7%, 32.4% and 9.5% of patients, respectively). We conclude that the incidence of serious airway complications is at least as high as it was during NAP4. Despite airway prediction being used, this is not informing subsequent management.     

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??Objective    To evaluate the efficacy of ropivacaine in extraction of mandibular impacted third molar. Methods    In this study 150 healthy patients who need to extract one mandibular impacted third molar were randomly divided into two groups. The experimental group was given 0.75% ropivacaine to get anesthesia??while the control group received 2% lidocaine. The time to onset and duration of action were noted. The visual analogue score??VAS??was recorded 30 min and 4 h after extraction. The rate of taking pain relieving drugs was noted. Blood pressure and pulse were monitored during the operation. Monitor the anesthetic complications and compare the anesthetic effect of the two drugs. Results               Ropivacaine had a significantly shorter onset and longer duration of oral anesthesia than lidocaine??P??0.05??. The experimental group had lower VAS 30 min and 4 h after operation??P??0.05??and fewer patients needed pain relieving drugs than the control group??P??0.05??. There was a slight decrease of the pulse in the experimental group 30 min postoperatively??P??0.05??. The pulse and blood pressure in the control group and the blood pressure in the experimental group had no obvious change. There was no complications in both groups. Conclusion    Ropivacaine may be suitable for time-consuming oral procedures because of its short onset??long duation??prolonged postoperative analgesia and minimal cardiovascular risk.     

Seton drainage and fibrin glue injection for complex anal fistulas

Objective The study aimed to evaluate the efficacy of fibrin glue in the treatment of complex anal fistula. Method Thirty consecutive patients with a complex anal fistula underwent glue instillation after an 8 week period of seton drainage. Cure was defined as complete closure of any secondary opening, absence of fistula seepage, and no abscess formation. Results The mean age of the patients (15 males) was 40.5 (range, 22.8–69.1) years. The mean duration of follow‐up was 11.7 (range, 0.2–33.5) months. Complete closure of the fistula was achieved in 17 patients at 1 month but in two patients a delayed abscess occurred. At the end of follow‐up, 15 (50%) patients were considered to have been cured. The success rate was no different in cases of Crohn’s disease or when postoperative antibiotic therapy was given. There was, however, a significant difference in success following regional vs general anaesthesia (68.4 vs 18.2% success, P = 0.02). Conclusion Fibrin glue cured 50% of our first 30 patients, and regional anaesthesia was predictive of success.     

Effects on upper airway collapsibility of presence of a pharyngeal catheter

Catheters that traverse the pharynx are often in place during clinical or research evaluations of upper airway function. The purpose of this study was to determine whether the presence of such catheters affects measures of upper airway collapsibility itself. To do so, pharyngeal critical closing pressure (Pcrit) and resistance upstream of the site of collapse Rus) were assessed in 24 propofol‐anaesthetized subjects (14 men) with and without a multi‐sensor oesophageal catheter (external diameter 2.7 mm) in place. Anaesthetic depth and posture were maintained constant throughout each study. Six subjects had polysomnography(PSG)‐defined obstructive sleep apnea (OSA) and 18 either did not have or were at low risk of OSA. Airway patency was maintained with positive airway pressure. At intervals, pressure was reduced by varying amounts to induce varying degrees of inspiratory flow limitation. The slope of the pressure flow relationship for flow‐limited breaths defined Rus. Pcrit was similar with the catheter in and out (?1.5 ± 5.4 cmH₂O and ?2.1 ± 5.6 cmH₂O, respectively, P = 0.14, n = 24). This remained the case both for those with PSG‐defined OSA (3.9 ± 2.2 cmH₂O and 2.6 ± 1.4 cmH₂O, n = 6) and those at low risk/without OSA (?3.3 ± 4.9 cmH₂O and ‐3.7 ± 5.6 cmH₂O, respectively, n = 18). Rus was similar with the catheter in and out (20.0 ± 12.3 cmH₂O mL^?1 s^?1 and 16.8 ± 10.1 cmH₂O mL^?1 s^?1, P = 0.22, n = 24). In conclusion, the presence of a small catheter traversing the pharynx had no significant effect on upper airway collapsibility in these anaesthestized subjects, providing reassurance that such measures can be made reliably in their presence.     

Subpectoral implantation of a cardioverter defibrillator under local anaesthesia

Objective—To evaluate patient acceptability of submuscular implantation of a cardioverter defibrillator (ICD) under local anaesthesia with conscious sedation.
Design—Retrospective review. Patient acceptability in the second half of the study was routinely assessed within 24 hours.
Setting—Regional cardiac centre.
Patients—45 consecutive patients with either aborted sudden death or haemodynamically unstable ventricular tachycardia were referred for ICD im- plantation.
Interventions—A subpectoral implantation technique was employed. Twelve procedures were performed under general anaesthesia. Thirty three patients were sedated with midazolam and diamorphine, and local anaesthesia was achieved with bupivicaine. Ventricular fibrillation for defibrillation threshold testing was induced by alternating current, T wave shock, or ultrarapid burst pacing. Patients were contacted after the procedure to assess acceptability.
Results—32 patients having implantation under local anaesthesia did not recall the surgical procedure. One patient described an awareness of "pushing" as the generator was positioned in the pocket. Seven patients said that the procedure was painless but recalled a test shock, four describing it as mildly uncomfortable. All 33 patients stated that they would be willing to have a second implant under local anaesthesia. Twelve patients who had the implant performed under general anaesthesia had no recollection of the procedure. Mean (SD) total procedure duration was significantly longer in those who had general anaesthesia (93 (16) v 67 (17) minutes; p = 0.0009).
Conclusions—Subpectoral implantation of ICDs may be performed safely with patient acceptability under local anaesthesia with conscious sedation.

Keywords: cardioverter defibrillator;  subpectoral implantation;  local anaesthesia;  pacing     

Pharmacokinetic–pharmacodynamic modelling in anaesthesia

Anaesthesiologists adjust drug dosing, administration system and kind of drug to the characteristics of the patient. They then observe the expected response and adjust dosing to the specific requirements according to the difference between observed response, expected response and the context of the surgery and the patient.The approach above can be achieved because on one hand quantification technology has made significant advances allowing the anaesthesiologist to measure almost any effect by using noninvasive, continuous measuring systems. On the other the knowledge on the relations between dosing, concentration, biophase dynamics and effect as well as detection of variability sources has been achieved as being the benchmark specialty for pharmacokinetic–pharmacodynamic (PKPD) modelling.The aim of the review is to revisit the most common PKPD models applied in the field of anaesthesia (i.e. effect compartmental, turnover, drug–receptor binding and drug interaction models) through representative examples. The effect compartmental model has been widely used in this field and there are multiple applications and examples. The use of turnover models has been limited mainly to describe respiratory effects. Similarly, cases in which the dissociation process of the drug–receptor complex is slow compared with other processes relevant to the time course of the anaesthetic effect are not frequent in anaesthesia, where in addition to a rapid onset, a fast offset of the response is required. With respect to the characterization of PD drug interactions different response surface models are discussed. Relevant applications that have changed the way modern anaesthesia is practiced are also provided.     

Managing the pain of labour: factors associated with the use of labour pain management for pregnant Australian women

Background

Despite high rates of women''s use of intrapartum pain management techniques, little is known about the factors that influence such use.

Objective

Examine the determinants associated with women''s use of labour pain management.

Design

Cross‐sectional survey of a substudy of women from the ‘young’ cohort of the Australian Longitudinal Study of Women''s Health (ALSWH).

Setting and participants

Women aged 31–35 years who identified as being pregnant or recently given birth in the 2009 ALSWH survey (n = 2445) were recruited for the substudy. The substudy survey was completed by 1835 women (RR = 79.2%).

Main variables studied

Determinants examined included pregnancy health and maternity care [including complementary and alternative medicine (CAM)] for their most recent pregnancy and any previous pregnancies. Participants'' attitudes and beliefs related to both CAM and maternity care were also included in the analysis.

Main outcome measures

The outcome measures examined were the use of both pharmacological and non‐pharmacological pain management techniques (NPMT).

Results

Differences were seen in the effects of demographics, health service utilization, health status, use of CAM, and attitudes and beliefs upon use of intrapartum pain management techniques across all categories. The only variable that was identified as a determinant for use of all types of pain management techniques was a previous caesarean section (CS).

Discussion and conclusions

The effect of key determinants on women''s use of pain management techniques differs significantly, and, other than CS, no one determinant is clearly influential in the use of all pain management options.     

Nerve stimulator for regional anaesthesia procedures with automatic interactive closed-loop control

Abstract

Peripheral nerve stimulators have widespread among anaesthesiologists and remain a popular technique. However, in commercial devices, the user has to manually adjust stimulus intensity. Thus, the aim of this study is to propose a method that allows automating the current intensity control. An earlier nerve stimulator prototype was modified to add an accelerometer and an sEMG module. The choice of these two sensors is aimed at the possibility of observing the mechanical and electrical responses of the muscle contraction evoked by the stimulation. The tests were performed in two steps. The first step was to observe how the sensors behave during stimulation and muscle contraction. The second step was to implement a control algorithm and to validate the automation technique. Comparing the two methods, no significant differences were found on procedure time (manual: 12.5?±?2.3; automatic: 11.6?±?1.9; ρ?=0.380) and blockade latency time (manual: 11.6?±?1.1; automatic: 11.9?±?1.2; ρ?=0.524). Comparing needle-nerve distance in manual or automatic mode, no significant differences were found for 1.0?mA, 0.8?mA, 0.5?mA and 0.3?mA. We conclude that the technique for automating the current intensity update, using accelerometer and/or electromyography, is satisfactory. Furthermore, we conclude that the use of the accelerometer alone is sufficient for detection of muscle contraction.     

The value of surveys in obstetric anaesthesia

BackgroundThe Obstetric Anaesthetists’ Association (OAA) has facilitated national surveys in obstetric anaesthesia since 1998. We wanted to examine trends in OAA-approved surveys since this time.MethodsOAA-approved surveys performed between January 1998 and December 2012 were examined for the year they were carried out, the format (postal or electronic), the target group and the response rate. We determined whether each survey was presented or published. For each survey published as a substantive paper, we identified the number of times the publication had been cited. We also surveyed lead obstetric anaesthetists and expert witnesses practising in obstetric anaesthesia on the perceived usefulness of OAA-approved surveys.ResultsOne hundred and thirty-five surveys approved by the OAA were carried out between 1998 and 2012. Response rates have fallen over the years, reaching a current plateau of 65%. Response rates varied with the target group. Seventy-eight percent of surveys were presented and 83% were published in some form. For surveys published as substantive papers (n=34, 25%), the median [IQR (range)] number of citations was 6 [3–11 (0–36)] per publication. Our survey of lead obstetric anaesthetists had a response rate of 62%. Those who replied rated OAA surveys a median [IQR (range)] of 6 [5–7 (1–9)] on a 0–10 scale of usefulness to their clinical practice.ConclusionsResponse rates to OAA-approved surveys have declined but remain acceptable despite an increase in the number of surveys performed. Most surveys were presented or published in some form.