The 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: protocol, methods and analysis of data

A survey of surgical patients' perspectives and preferences towards general anesthesia techniques and shared-decision making

BACKGROUND

The decision about which type of general anesthetic to administer is typically made by the clinical team without patient engagement. This study examined patients' preferences, experiences, attitudes, beliefs, perceptions, and perceived social norms about anesthesia and about engaging in the decision regarding general anesthetic choice with their clinician.

METHODS

We conducted a survey in the United States, sent to a panel of surgical patients through Qualtrics (Qualtrics, Provo, UT) from March 2022 through May 2022. Questions were developed based on the Theory of Planned Behavior and validated measures were used when available. A patient partner who had experienced both intravenous and inhaled anesthesia contributed to the development and refinement of the questions.

RESULTS

A total of 806 patients who received general anesthesia for an elective procedure in the last five years completed the survey. 43% of respondents preferred a patient-led decision making role and 28% preferred to share decision making with their clinical team, yet only 7.8% reported being engaged in full shared decision making about the anesthesia they received. Intraoperative awareness, pain, nausea, vomiting and quickly returning to work and usual household activities were important to respondents. Waking up in the middle of surgery was the most commonly reported concern, despite this experience being reported only 8% of the time. Most patients (65%) who searched for information about general anesthesia noted that it took a lot of effort to find the information, and 53% agreed to feeling frustrated during the search.

CONCLUSIONS

Most patients prefer a patient-led or shared decision making process when it comes to their anesthetic care and want to be engaged in the decision. However, only a small percentage of patients reported being fully engaged in the decision. Further studies should inform future shared decision-making tools, informed consent materials, educational materials and framing of anesthetic choices for patients so that they are able to make a choice regarding the anesthetic they receive.

Assessment of Amnesic Effect and the Depth of Hypnosis During Therapeutic Inhalation of Xenon-Oxygen Mixture

The current literature lacks data on the incidence of intraoperative awakening during xenon anesthesia. This could be due to amnesia preventing memories of the intraoperative awakening.

The objective: to determine the concentration of xenon in the xenon-oxygen mixture, which causes amnesia for events during inhalation in 100% of patients, and to make correlations with the depth of hypnosis as per Kugler scale.

Subjects and Methods: 34 patients with chronic neurogenic pain who received 111 20-minute inhalations with concentration of xenon up to 50% were included in the study. Amnesia evaluation, EEG monitoring, and pain assessment on a visual analog scale (VAS) were performed.

Results. Amnesic effect developed in 100% of patients at xenon concentration of 45%. On inhalation of xenon at concentrations of up to 50%, EEG changes did not exceed D1 grade on Kugler scale. The decrease in bispectral index (BIS) did not reach the level of deep sedation (Me 96.2%) at xenon concentration of 50%. The decrease in pain on VAS was approximately 60%.

Conclusions. Xenon inhalations cause transient congradic amnesia at concentrations of 45% or more. The accuracy of the BIS monitoring readings may be reduced when using xenon in a monovariant. Inhalations of xenon-oxygen mixture in concentrations up to 50% showed good analgesic properties in the framework of combined therapy of chronic pain syndrome.

Optimizing Reversal of Neuromuscular Block in Older Adults: Sugammadex or Neostigmine

Residual neuromuscular paralysis, the presence of clinically significant weakness after administration of pharmacologic neuromuscular blockade reversal, is associated with postoperative pulmonary complications and is more common in older patients. In contemporary anesthesia practice, reversal of neuromuscular blockade is accomplished with neostigmine or sugammadex. Neostigmine, an acetylcholinesterase inhibitor, increases the concentration of acetylcholine at the neuromuscular junction, providing competitive antagonism of neuromuscular blocking drug and facilitating muscle contraction. Sugammadex, a modified gamma-cyclodextrin, antagonizes neuromuscular blockade by encapsulating rocuronium and vecuronium in a one-to-one ratio for renal clearance, a pharmacokinetic property that led to the recommendation that sugammadex not be administered to those with end-stage renal disease. While data are limited, reports suggest sugammadex is efficacious and well tolerated in individuals with reduced renal function. Sugammadex provides a more rapid and complete reversal of neuromuscular blockade than neostigmine. There is also accumulating evidence that sugammadex may provide a protective effect against the development of postoperative pulmonary complications, nausea, and vomiting, and that it may have beneficial effects on the rate of bowel and bladder recovery after surgery. Accordingly, sugammadex administration is beneficial for most older patients undergoing surgery.

An integrative review of method types used in the study of medication error during anaesthesia: implications for estimating incidence

To meet the WHO vision of reducing medication errors by 50%, it is essential to know the current error rate. We undertook an integrative review of the literature, using a systematic search strategy. We included studies that provided an estimate of error rate (i.e. both numerator and denominator data), regardless of type of study (e.g. RCT or observational study). Under each method type, we categorised the error rate by type, by classification used by the primary studies (e.g. wrong drug, wrong dose, wrong time), and then pooled numerator and denominator data across studies to obtain an aggregate error rate for each method type. We included a total of 30 studies in this review. Of these, two studies were national audit projects containing relevant data, and for 28 studies we identified five discrete method types: retrospective recall (6), self-reporting (7), observational (5), large databases (7), and observing for drug calculation errors (3). Of these 28 studies we included 22 for a numerical analysis and used six to inform a narrative review. Drug error is recalled by ~1 in 5 anaesthetists as something that happened over their career; in self-reports there is an admitted rate of ~1 in 200 anaesthetics. In observed practice, error is seen in almost every anaesthetic. In large databases, drug error constitutes ~10% of anaesthesia incidents reported. Wrong drug or dose form the most common type of error across all five study method types (especially dosing error in paediatric studies). We conclude that medication error is common in anaesthetic practice, although we were uncertain of the precise frequency or extent of harm. Studies concerning medication error are very heterogenous, and we recommend consideration of standardised reporting as in other research domains.

Incidence of accidental awareness during general anaesthesia in obstetrics: a multicentre, prospective cohort study

General anaesthesia for obstetric surgery has distinct characteristics that may contribute towards a higher risk of accidental awareness during general anaesthesia. The primary aim of this study was to investigate the incidence, experience and psychological implications of unintended conscious awareness during general anaesthesia in obstetric patients. From May 2017 to August 2018, 3115 consenting patients receiving general anaesthesia for obstetric surgery in 72 hospitals in England were recruited to the study. Patients received three repetitions of standardised questioning over 30 days, with responses indicating memories during general anaesthesia that were verified using interviews and record interrogation. A total of 12 patients had certain/probable or possible awareness, an incidence of 1 in 256 (95%CI 149-500) for all obstetric surgery. The incidence was 1 in 212 (95%CI 122-417) for caesarean section surgery. Distressing experiences were reported by seven (58.3%) patients, paralysis by five (41.7%) and paralysis with pain by two (16.7%). Accidental awareness occurred during induction and emergence in nine (75%) of the patients who reported awareness. Factors associated with accidental awareness during general anaesthesia were: high BMI (25-30 kg.m^-2 ); low BMI (<18.5 kg.m^-2 ); out-of-hours surgery; and use of ketamine or thiopental for induction. Standardised psychological impact scores at 30 days were significantly higher in awareness patients (median (IQR [range]) 15 (2.7-52.0 [2-56]) than in patients without awareness 3 (1-9 [0-64]), p = 0.010. Four patients had a provisional diagnosis of post-traumatic stress disorder. We conclude that direct postoperative questioning reveals high rates of accidental awareness during general anaesthesia for obstetric surgery, which has implications for anaesthetic practice, consent and follow-up.

Nitrous oxide-based vs. nitrous oxide-free general anaesthesia and accidental awareness in surgical patients: an abridged Cochrane systematic review

Accidental awareness during general anaesthesia can arise from a failure to deliver sufficient anaesthetic agent, or from a patient's resistance to an expected sufficient dose of such an agent. Awareness is 'explicit' if the patient is subsequently able to recall the event. We conducted a systematic review into the effect of nitrous oxide used as part of a general anaesthetic on the risk of accidental awareness in people over the age of five years undergoing general anaesthesia for surgery. We included 15 randomised controlled trials, 14 of which, representing a total of 3439 participants, were included in our primary analysis of the frequency of accidental awareness events. The awareness incidence rate was rare within these studies, and all were considered underpowered with respect to this outcome. The risk of bias across all studies was judged to be high, and 76% of studies failed adequately to conceal participant allocation. We considered the available evidence to be of very poor quality. There were a total of three accidental awareness events reported in two studies, one of which reported that the awareness was the result of a kink in a propofol intravenous line. There were insufficient data to conduct a meta- or sub-group analysis and there was insufficient evidence to draw outcome-related conclusions. We can, however, recommend that future studies focus on potentially high-risk groups such as obstetric or cardiac surgery patients, or those receiving neuromuscular blocking drugs or total intravenous anaesthesia.

AAGBI: Safer pre-hospital anaesthesia 2017: Association of Anaesthetists of Great Britain and Ireland

Pre-hospital emergency anaesthesia with oral tracheal intubation is the technique of choice for trauma patients who cannot maintain their airway or achieve adequate ventilation. It should be carried out as soon as safely possible, and performed to the same standards as in-hospital emergency anaesthesia. It should only be conducted within organisations with comprehensive clinical governance arrangements. Techniques should be straightforward, reproducible, as simple as possible and supported by the use of checklists. Monitoring and equipment should meet in-hospital anaesthesia standards. Practitioners need to be competent in the provision of in-hospital emergency anaesthesia and have supervised pre-hospital experience before carrying out pre-hospital emergency anaesthesia. Training programmes allowing the safe delivery of pre-hospital emergency anaesthesia by non-physicians do not currently exist in the UK. Where pre-hospital emergency anaesthesia skills are not available, oxygenation and ventilation should be maintained with the use of second-generation supraglottic airways in patients without airway reflexes, or basic airway manoeuvres and basic airway adjuncts in patients with intact airway reflexes.

Neuromuscular blockade in the elderly patient

Neuromuscular blockade is a desirable or even essential component of general anesthesia for major surgical operations. As the population continues to age, and more operations are conducted in the elderly, due consideration must be given to neuromuscular blockade in these patients to avoid possible complications. This review considers the pharmacokinetics and pharmacodynamics of neuromuscular blockade that may be altered in the elderly. Compartment distribution, metabolism, and excretion of drugs may vary due to age-related changes in physiology, altering the duration of action with a need for reduced dosage (eg, aminosteroids). Other drugs (atracurium, cisatracurium) have more reliable duration of action and should perhaps be considered for use in the elderly. The range of interpatient variability that neuromuscular blocking drugs may exhibit is then considered and drugs with a narrower range, such as cisatracurium, may produce more predictable, and inherently safer, outcomes. Ultimately, appropriate neuromuscular monitoring should be used to guide the administration of muscle relaxants so that the risk of residual neuromuscular blockade postoperatively can be minimized. The reliability of various monitoring is considered. This paper concludes with a review of the various reversal agents, namely, anticholinesterase drugs and sugammadex, and the alterations in dosing of these that should be considered for the elderly patient.

The 2015 Gerard W. Ostheimer Lecture: What's New in Labor Analgesia and Cesarean Delivery

Every year the Board of Directors of the Society for Obstetric Anesthesia and Perinatology selects an individual to review the literature pertinent to obstetric anesthesiology published the previous calendar year. This individual selects the most notable contributions, creates a syllabus of the articles, and then presents his/her overview in an annual lecture named in honor of the late Gerard W. Ostheimer, a pioneering obstetric anesthesiologist from the Brigham and Women's Hospital. This article reviews the literature published in 2014 focusing on the themes of labor analgesia and cesarean delivery. Its contents were presented as the Gerard W. Ostheimer Lecture at the 47th Annual Meeting of the Society for Obstetric Anesthesia and Perinatology, May 16, 2015, in Colorado Springs, Colorado. The syllabus is available as Supplemental Digital Content (http://links.lww.com/AA/B397).

Recommendations for standards of monitoring during anaesthesia and recovery 2015: Association of Anaesthetists of Great Britain and Ireland

This guideline updates and replaces the 4th edition of the AAGBI Standards of Monitoring published in 2007. The aim of this document is to provide guidance on the minimum standards for physiological monitoring of any patient undergoing anaesthesia or sedation under the care of an anaesthetist. The recommendations are primarily aimed at anaesthetists practising in the United Kingdom and Ireland. Minimum standards for monitoring patients during anaesthesia and in the recovery phase are included. There is also guidance on monitoring patients undergoing sedation and also during transfer of anaesthetised or sedated patients. There are new sections discussing the role of monitoring depth of anaesthesia, neuromuscular blockade and cardiac output. The indications for end-tidal carbon dioxide monitoring have been updated.

An observational study of the 'isolated forearm technique' in unparalysed, spontaneously breathing patients

The isolated forearm technique enables a patient, otherwise paralysed by neuromuscular blockade, to communicate by movement if wakeful during surgery. The positive response rate to verbal command is high (~32%). The 5th National Audit Project recommended that this monitoring technique should become more widely taught and considered, so this study was designed to assess its utility as a standard of care in unparalysed patients. A positive response rate as high as in the paralysed would justify local adoption. Therefore, 100 consecutive patients undergoing urology surgery were given verbal commands to move at two-minute intervals from induction of anaesthesia (fentanyl and propofol) to full emergence and extubation of the supraglottic airway. Anaesthesia was maintained with isoflurane in oxygen/nitrous oxide. Although 24 patients moved during surgery (and therefore needed additional anaesthetic), none moved to verbal command. Even at extubation, when patients moved to expel the airway, there was no response to command until after wakening. These results suggest that in contrast to its use in paralysed patients, the isolated forearm technique does not yield useful information about the patient's state of wakefulness in the unparalysed. Another interpretation is that unparalysed patients are less prone to wakefulness than the paralysed.

Peri-operative management of the obese surgical patient 2015: Association of Anaesthetists of Great Britain and Ireland Society for Obesity and Bariatric Anaesthesia

Guidelines are presented for the organisational and clinical peri-operative management of anaesthesia and surgery for patients who are obese, along with a summary of the problems that obesity may cause peri-operatively. The advice presented is based on previously published advice, clinical studies and expert opinion.

The 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: summary of main findings and risk factors

We present the main findings of the 5th National Audit Project on accidental awareness during general anaesthesia. Incidences were estimated using reports of accidental awareness as the numerator, and a parallel national anaesthetic activity survey to provide denominator data. The incidence of certain/probable and possible accidental awareness cases was ~1:19 600 anaesthetics (95% CI 1:16 700-23 450). However, there was considerable variation across subtypes of techniques or subspecialties. The incidence with neuromuscular blockade was ~1:8200 (1:7030-9700), and without it was ~1:135 900 (1:78 600-299 000). The cases of accidental awareness during general anaesthesia reported to 5th National Audit Project were overwhelmingly cases of unintended awareness during neuromuscular blockade. The incidence of accidental awareness during caesarean section was ~1:670 (1:380-1300). Two thirds (82, 66%) of cases of accidental awareness experiences arose in the dynamic phases of anaesthesia, namely induction of and emergence from anaesthesia. During induction of anaesthesia, contributory factors included: use of thiopental; rapid sequence induction; obesity; difficult airway management; neuromuscular blockade; and interruptions of anaesthetic delivery during movement from anaesthetic room to theatre. During emergence from anaesthesia, residual paralysis was perceived by patients as accidental awareness, and commonly related to a failure to ensure full return of motor capacity. One third (43, 33%) of accidental awareness events arose during the maintenance phase of anaesthesia, most due to problems at induction or towards the end of anaesthesia. Factors increasing the risk of accidental awareness included: female sex; age (younger adults, but not children); obesity; anaesthetist seniority (junior trainees); previous awareness; out-of-hours operating; emergencies; type of surgery (obstetric, cardiac, thoracic); and use of neuromuscular blockade. The following factors were not risk factors for accidental awareness: ASA physical status; race; and use or omission of nitrous oxide. We recommend that an anaesthetic checklist, to be an integral part of the World Health Organization Safer Surgery checklist, is introduced as an aid to preventing accidental awareness. This paper is a shortened version describing the main findings from 5th National Audit Project - the full report can be found at http://www.nationalauditprojects.org.uk/NAP5_home#pt.