Assessing a novel second generation laryngeal mask airway using the 'ADEPT' approach: results from the LMA® Protector™ observational study

To address the problem of lack of clinical evidence for airway devices introduced to the market, the Difficult Airway Society (UK) developed an approach (termed ADEPT; Airway Device Evaluation Project Team) to standardise the model for device evaluation. Under this framework we assessed the LMA Protector, a second generation laryngeal mask airway. A total of 111 sequential adult patients were recruited and the LMA Protector inserted after induction of general anaesthesia. Effective insertion was confirmed by resistance to further distal movement, manual ventilation, and listening for gas leakage at the mouth. The breathing circuit was connected to the airway channel and airway patency confirmed with manual test ventilation at 20 cm H20 (water) pressure for 3 s. Data was collected in relation to the time for placement, intraoperative performance and postoperative performance of the airway device. Additionally, investigators rated the ease of insertion and adequacy of lung ventilation on a 5-point scale. The median (interquartile range [range]) time taken to insertion of the device was 31 (26-40[14-780]) s with the ability to ventilate after device insertion 100 (95% CI 96.7- 100)%. Secondary endpoints included one or more manoeuvres 60.3 (95% CI 50.6-69.5)% cases requiring to assist insertion; a median ease of insertion score of 4 (2-5[3-5]), and a median adequacy of ventilation score of 5 (5-5[4-5]). However, the first time insertion rate failure was 9.9% (95% CI 5.1-17.0%). There were no episodes of patient harm recorded, particularly desaturation. The LMA Protector appears suitable for clinical use, but an accompanying article discusses our reflections on the ADEPT approach to studying airway devices from a strategic perspective.

Patient characteristics, anaesthetic workload and techniques in the UK: an analysis from the 7th National Audit Project (NAP7) activity survey

Detailed contemporary knowledge of the characteristics of the surgical population, national anaesthetic workload, anaesthetic techniques and behaviours are essential to monitor productivity, inform policy and direct research themes. Every 3-4 years, the Royal College of Anaesthetists, as part of its National Audit Projects (NAP), performs a snapshot activity survey in all UK hospitals delivering anaesthesia, collecting patient-level encounter data from all cases under the care of an anaesthetist. During November 2021, as part of NAP7, anaesthetists recorded details of all cases undertaken over 4 days at their site through an online survey capturing anonymous patient characteristics and anaesthetic details. Of 416 hospital sites invited to participate, 352 (85%) completed the activity survey. From these, 24,177 reports were returned, of which 24,172 (99%) were included in the final dataset. The work patterns by day of the week, time of day and surgical specialty were similar to previous NAP activity surveys. However, in non-obstetric patients, between NAP5 (2013) and NAP7 (2021) activity surveys, the estimated median age of patients increased by 2.3 years from median (IQR) of 50.5 (28.4-69.1) to 52.8 (32.1-69.2) years. The median (IQR) BMI increased from 24.9 (21.5-29.5) to 26.7 (22.3-31.7) kg.m^-2 . The proportion of patients who scored as ASA physical status 1 decreased from 37% in NAP5 to 24% in NAP7. The use of total intravenous anaesthesia increased from 8% of general anaesthesia cases to 26% between NAP5 and NAP7. Some changes may reflect the impact of the COVID-19 pandemic on the anaesthetic population, though patients with confirmed COVID-19 accounted for only 149 (1%) cases. These data show a rising burden of age, obesity and comorbidity in patients requiring anaesthesia care, likely to impact UK peri-operative services significantly.

The effect of first trimester body mass index on the changes in the upper lip bite test classification before and after delivery: A prospective observational study

Background

The difficult airway (DA) assessment and management of pregnant woman has always brought specific challenges. The aim of this study was to investigate the effect of labor on the airway by assessing changes in the upper lip bite test (ULBT) classes and to explore its correlation with the first trimester's body mass index (BMI).

Methods

According to the BMI of the first trimester, 354 full-term women were divided into low BMI group, normal BMI group and high BMI group. The ULBT class and pregnancy outcome were recorded and compared at early labor, after delivery, and 48 h after delivery.

Results

The ULBT class was increased in 75(21.1%) patients after delivery. Compared to the normal BMI group, the high BMI group had a higher probability of increasing (34.8 vs. 17.5%; P = 0.002). The number of women with ULBT class 2–3 increased to 157, which was 1.48 times that of early labor. The number of women with ULBT class 3 increased from 4 to 16, of which 7 (53.8%) were from the high BMI group. Binary logistic regression analysis showed that first trimester's BMI was associated with a significant increase in ULBT class after delivery (adjusted odds ratio [aOR] = 2.13 [0.91–4.98], P = 0.02). The ULBT classes of the three groups tended to return to their initial level 48 h after delivery (P > 0.05).

Conclusion

Labor results in an approximately one-fifth increase in ULBT class. Being overweight or obese in the first trimester is associated with an increased risk of DA during labor.

Trial registration

This study was registered in the Chinese Clinical Trial Registry (http://www.chictr.org.cn) on September 26, 2020. Registration number ChiCTR2000038643.

Anaesthesia and the development of functional neurological disorder: A systematic review and case series

OBJECTIVE

There are reports of functional neurological disorder (FND) developing after anaesthesia, though separating any aetiological role from other possible factors is challenging. We aimed to systematically review all published cases of post-anaesthetic FND to see if any common factors supported an anaesthetic role. We also aimed to identify all cases of post-anaesthetic FND arising in our FND clinic, to obtain an estimate of its frequency.

METHODS

For the review, a systematic search for published cases of FND developing within 48 h of anaesthesia was conducted in June 2022. For the case series, the medical records of all patients attending an FND clinic in Melbourne between 2017 and 2019 were examined, and all cases with FND within 48 h of anaesthesia extracted.

RESULTS

36 published cases were identified for the review. Sixteen described preceding stressors and 16 psychiatric diagnoses, including 8 with previous FND. Thirty-two (92%) had undergone general anaesthesia, most commonly for obstetric procedures. Motor/sensory loss was the most common presentation, followed by seizures and coma. Most (80.5%) developed symptoms immediately on induction or cessation of anaesthesia. For the case series, 8 of 107 clinic patients (7.5%), developed FND within 48 h of anaesthesia. All had previous psychiatric diagnoses, including 3 with previous FND. Three underwent general anaesthesia and 3 procedural sedation, with seizures the most common presentation. All developed symptoms immediately on induction or cessation of anaesthesia.

CONCLUSION

These cases provide some support for an aetiological role for anaesthesia: there is evidence for an anaesthetic 'model' for the symptoms of FND that arise, they largely arise with the onset or termination of anaesthesia, and they arise most frequently during general anaesthesia or sedation.

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.

Quantitative evaluation of aerosol generation from upper airway suctioning assessed during tracheal intubation and extubation sequences in anaesthetized patients

BACKGROUND

Open respiratory suctioning is defined as an aerosol generating procedure (AGP). Laryngopharyngeal suctioning, used to clear secretions during anaesthesia, is widely managed as an AGP. However, it is uncertain whether upper airway suctioning should be designated as an AGP due to the lack of both aerosol and epidemiological evidence.

AIM

To assess the relative risk of aerosol generation by upper airway suctioning during tracheal intubation and extubation in anaesthetized patients.

METHODS

This prospective environmental monitoring study was undertaken in an ultraclean operating theatre setting to assay aerosol concentrations during intubation and extubation sequences, including upper airway suctioning, for patients undergoing surgery (N=19). An optical particle sizer (particle size 0.3-10 μm) sampled aerosol 20 cm above the patient's mouth. Baseline recordings (background, tidal breathing and volitional coughs) were followed by intravenous induction of anaesthesia with neuromuscular blockade. Four periods of laryngopharyngeal suctioning were performed with a Yankauer sucker: pre-laryngoscopy, post-intubation, pre-extubation and post-extubation.

FINDINGS

Aerosol was reliably detected {median 65 [interquartile range (IQR) 39-259] particles/L} above background [median 4.8 (IQR 1-7) particles/L, P<0.0001] when sampling in close proximity to the patient's mouth during tidal breathing. Upper airway suctioning was associated with a much lower average aerosol concentration than breathing [median 6.0 (IQR 0-12) particles/L, P=0.0007], and was indistinguishable from background (P>0.99). Peak aerosol concentrations recorded during suctioning [median 45 (IQR 30-75) particles/L] were much lower than during volitional coughs [median 1520 (IQR 600-4363) particles/L, P<0.0001] and tidal breathing [median 540 (IQR 300-1826) particles/L, P<0.0001].

CONCLUSION

Upper airway suctioning during airway management was not associated with a higher aerosol concentration compared with background, and was associated with a much lower aerosol concentration compared with breathing and coughing. Upper airway suctioning should not be designated as a high-risk AGP.

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.

Ethanol reduces the minimum alveolar concentration of sevoflurane in rats

A high number of trauma patients are under the influence of alcohol. Since many of them need immediate surgical procedures, it is imperative to be aware of the interaction of alcohol with general anesthesia. To counter challenges that arise from clinical studies, we designed an animal experiment in which 48 adult Wistar rats either received 1 g · kg-1 ethanol, 2 g · kg-1 ethanol or placebo via intraperitoneal application. Subsequently, they were anesthetized with an individual concentration of sevoflurane. The minimum alveolar concentration (MAC) of the different groups was assessed using Dixon's up-and-down design and isotonic regression methods. The bootstrap estimate of the MAC of sevoflurane in the placebo group was 2.24 vol% (95% CI 1.97-2.94 vol%). In the low dose ethanol group, the bootstrap estimate was 1.65 vol% (95% CI 1.40-1.98 vol%), and in the high dose ethanol group, it was 1.08 vol% (95% CI 0.73-1.42 vol%). We therefore report that intraperitoneal application of 1 g · kg-1 or 2 g · kg-1 ethanol both resulted in a significant reduction of the MAC of sevoflurane in adult Wistar rats: by 26.3% and 51.8% respectively as compared to placebo.

A quantitative evaluation of aerosol generation during supraglottic airway insertion and removal

Many guidelines consider supraglottic airway use to be an aerosol-generating procedure. This status requires increased levels of personal protective equipment, fallow time between cases and results in reduced operating theatre efficiency. Aerosol generation has never been quantitated during supraglottic airway use. To address this evidence gap, we conducted real-time aerosol monitoring (0.3-10-µm diameter) in ultraclean operating theatres during supraglottic airway insertion and removal. This showed very low background particle concentrations (median (IQR [range]) 1.6 (0-3.1 [0-4.0]) particles.l-1 ) against which the patient's tidal breathing produced a higher concentration of aerosol (4.0 (1.3-11.0 [0-44]) particles.l-1 , p = 0.048). The average aerosol concentration detected during supraglottic airway insertion (1.3 (1.0-4.2 [0-6.2]) particles.l-1 , n = 11), and removal (2.1 (0-17.5 [0-26.2]) particles.l-1 , n = 12) was no different to tidal breathing (p = 0.31 and p = 0.84, respectively). Comparison of supraglottic airway insertion and removal with a volitional cough (104 (66-169 [33-326]), n = 27), demonstrated that supraglottic airway insertion/removal sequences produced <4% of the aerosol compared with a single cough (p < 0.001). A transient aerosol increase was recorded during one complicated supraglottic airway insertion (which initially failed to provide a patent airway). Detailed analysis of this event showed an atypical particle size distribution and we subsequently identified multiple sources of non-respiratory aerosols that may be produced during airway management and can be considered as artefacts. These findings demonstrate supraglottic airway insertion/removal generates no more bio-aerosol than breathing and far less than a cough. This should inform the design of infection prevention strategies for anaesthetists and operating theatre staff caring for patients managed with supraglottic airways.

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.

The impact of COVID-19 on anaesthesia and critical care services in the UK: a serial service evaluation

Between October 2020 and January 2021, we conducted three national surveys to track anaesthetic, surgical and critical care activity during the second COVID‐19 pandemic wave in the UK. We surveyed all NHS hospitals where surgery is undertaken. Response rates, by round, were 64%, 56% and 51%. Despite important regional variations, the surveys showed increasing systemic pressure on anaesthetic and peri‐operative services due to the need to support critical care pandemic demands. During Rounds 1 and 2, approximately one in eight anaesthetic staff were not available for anaesthetic work. Approximately one in five operating theatres were closed and activity fell in those that were open. Some mitigation was achieved by relocation of surgical activity to other locations. Approximately one‐quarter of all surgical activity was lost, with paediatric and non‐cancer surgery most impacted. During January 2021, the system was largely overwhelmed. Almost one‐third of anaesthesia staff were unavailable, 42% of operating theatres were closed, national surgical activity reduced to less than half, including reduced cancer and emergency surgery. Redeployed anaesthesia staff increased the critical care workforce by 125%. Three‐quarters of critical care units were so expanded that planned surgery could not be safely resumed. At all times, the greatest resource limitation was staff. Due to lower response rates from the most pressed regions and hospitals, these results may underestimate the true impact. These findings have important implications for understanding what has happened during the COVID‐19 pandemic, planning recovery and building a system that will better respond to future waves or new epidemics.

A systematic review of the use of virtual reality or dental smartphone applications as interventions for management of paediatric dental anxiety

Background

Virtual reality (VR) has been used successfully in medicine both as a distraction tool during procedures, and as an acclimatisation tool to prepare for a procedure or experience. It has not yet become widely used in dentistry, but could theoretically have a role in exposure-based acclimatisation for dental experiences.

Methods

To examine the use of VR or bespoke dental smartphone applications pre- or perioperatively in dentistry, to decrease anxiety in a paediatric population attending for dental examination or treatment, compared with children/adolescents who receive no intervention, or more conventional behavioural management techniques.

Searches were made of eight electronic databases: the Cochrane Oral Health Group’s Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE(PubMed), EMBASE, PsycINFO, CINAHL, Scopus and Web of Science. Further searches reference cross‐checks were performed to identify studies that were not discovered online.

Results

Systematic reviews and randomised control trials have demonstrated the successful use of VR to both distract patients perioperatively during medical procedures, and also preoperatively to prepare them for these interventions. However, to date, VR has only been applied to dentistry in a very limited number of studies. Three studies using virtual reality in a dental setting demonstrated decreased pain and anxiety compared with no intervention. All three of these studies were carried out in the perioperative period. A fourth study used a bespoke dental app and imagery to prepare patients with Autism Spectrum Disorder (ASD) for dental treatment, finding statistically significant decreases in both the number of appointments and number of attempts required to carry out a procedure.

Conclusion

VR is a promising tool which to date has been under-utilised in dentistry. High quality, clinical studies are required to assess the use of preoperative VR and smartphone applications to prepare patients for dental examination and procedures under local or general anaesthetic.

The effect of oral Δ-9-tetrahydrocannabinol on the minimal alveolar concentration of sevoflurane: A randomised, controlled, observer-blinded experimental study

BACKGROUND

Cannabis has increasingly been used for medical and recreational purposes. The main pharmacological compound in cannabis is tetrahydrocannabinol (THC), which has sedative, anxiolytic and analgesic effects. In some animal models, THC has also been shown to reduce the minimum alveolar concentration (MAC) of halothane and cyclopropane, but its effect on sevoflurane, currently the most commonly used inhalational anaesthetic agent, has not been investigated.

OBJECTIVE

To investigate the effect of THC on the MAC of sevoflurane in rats.

METHODS

Observer-blinded, randomised controlled trial.

SETTING

Centre for Biomedical Research of the Medical University of Vienna, 2019.

INDIVIDUALS

Thirty-eight adult Wistar rats.

INTERVENTIONS

The rats were allocated randomly into one of two groups. Group A received THC 10 mg kg and group B received the corresponding volume of placebo via gastric gavage (administration through a tube placed in the distal oesophagus). The rats were then individually anaesthetised in an airtight sevoflurane-flooded chamber, and the MAC in both groups was determined using Dixon's up-and-down method. Blood samples were drawn to measure serum concentrations of THC.

MAIN OUTCOME MEASURES

The primary outcome was the MAC of sevoflurane in Groups A and B.

RESULTS

The bootstrap estimate of the MAC of sevoflurane was 2.1 (95% confidence interval 1.8 to 2.4) vol% in the THC group and 2.8 (95% confidence interval 2.7 to 2.9) vol% in the placebo group, corresponding to a significant MAC reduction of 26% in response to THC.

CONCLUSION

Gastric administration of THC 10 mg kg significantly reduced the MAC of sevoflurane by 26%.

TRIAL REGISTRATION

Not applicable.

Inhaled Anesthetics: Environmental Role, Occupational Risk, and Clinical Use

Inhaled anesthetics have been in clinical use for over 150 years and are still commonly used in daily practice. The initial view of inhaled anesthetics as indispensable for general anesthesia has evolved during the years and, currently, its general use has even been questioned. Beyond the traditional risks inherent to any drug in use, inhaled anesthetics are exceptionally strong greenhouse gases (GHG) and may pose considerable occupational risks. This emphasizes the importance of evaluating and considering its use in clinical practices. Despite the overwhelming scientific evidence of worsening climate changes, control measures are very slowly implemented. Therefore, it is the responsibility of all society sectors, including the health sector to maximally decrease GHG emissions where possible. Within the field of anesthesia, the potential to reduce GHG emissions can be briefly summarized as follows: Stop or avoid the use of nitrous oxide (N2O) and desflurane, consider the use of total intravenous or local-regional anesthesia, invest in the development of new technologies to minimize volatile anesthetics consumption, scavenging systems, and destruction of waste gas. The improved and sustained awareness of the medical community regarding the climate impact of inhaled anesthetics is mandatory to bring change in the current practice.

Analysis of anaesthesia services to calculate national need and supply of anaesthetics in Switzerland during the COVID-19 pandemic

Background

In Switzerland, details of current anaesthesia practice are unknown. However, they are urgently needed to manage anaesthesia drug supply in times of drug shortages due to the pandemic.

Methods

We surveyed all Swiss anaesthesia institutions in April 2020 to determine their annual anaesthesia activity. Together with a detailed analysis on anaesthetic drug use of a large, representative Swiss anaesthesia index institution, calculations and projections for the annual need of anaesthetics in Switzerland were made. Only those drugs have been analysed that are either being used very frequently or that have been classified critical with regard to their supply by the pharmacy of the index institution or the Swiss Federal Office of Public Health.

Results

The response rate to our questionnaire was 98%. Out of the present 188 Swiss anaesthesia institutions, 185 responded. In Switzerland, the annual number of anaesthesias was 1’071’054 (12’445 per 100’000 inhabitants) with a mean anaesthesia time of 2.03 hours. Teaching hospitals (n = 54) performed more than half (n = 572’231) and non-teaching hospitals (n = 103) provided almost half of all anaesthesias (n = 412’531). Thereby, private hospitals conducted a total of 290’690 anaesthesias. Finally, office-based anaesthesia institutions with mainly outpatients (n = 31) administered 86’292 anaesthesias. Regarding type of anaesthesia provided, two thirds were general anaesthesias (42% total intravenous, 17% inhalation, 8% combined), 20% regional and 12% monitored anaesthesia care. Projecting for example the annual need for propofol in anaesthesia, Switzerland requires 48’573 L of propofol 1% which corresponds to 5’644 L propofol 1% per 100’000 inhabitants every year.

Conclusions

To actively manage anaesthesia drug supply in the context of the current pandemic, it is mandatory to have a detailed understanding of the number and types of anaesthesias provided. On this basis, the Swiss annual consumption of anaesthetics could be projected and the replenishment organized.

General anaesthetic and airway management practice for obstetric surgery in England: a prospective, multicentre observational study

There are no current descriptions of general anaesthesia characteristics for obstetric surgery, despite recent changes to patient baseline characteristics and airway management guidelines. This analysis of data from the direct reporting of awareness in maternity patients' (DREAMY) study of accidental awareness during obstetric anaesthesia aimed to describe practice for obstetric general anaesthesia in England and compare with earlier surveys and best-practice recommendations. Consenting patients who received general anaesthesia for obstetric surgery in 72 hospitals from May 2017 to August 2018 were included. Baseline characteristics, airway management, anaesthetic techniques and major complications were collected. Descriptive analysis, binary logistic regression modelling and comparisons with earlier data were conducted. Data were collected from 3117 procedures, including 2554 (81.9%) caesarean deliveries. Thiopental was the induction drug in 1649 (52.9%) patients, compared with propofol in 1419 (45.5%). Suxamethonium was the neuromuscular blocking drug for tracheal intubation in 2631 (86.1%), compared with rocuronium in 367 (11.8%). Difficult tracheal intubation was reported in 1 in 19 (95%CI 1 in 16-22) and failed intubation in 1 in 312 (95%CI 1 in 169-667). Obese patients were over-represented compared with national baselines and associated with difficult, but not failed intubation. There was more evidence of change in practice for induction drugs (increased use of propofol) than neuromuscular blocking drugs (suxamethonium remains the most popular). There was evidence of improvement in practice, with increased monitoring and reversal of neuromuscular blockade (although this remains suboptimal). Despite a high risk of difficult intubation in this population, videolaryngoscopy was rarely used (1.9%).

Patient-maintained propofol sedation for adult patients undergoing surgical or medical procedures: a scoping review of current evidence and technology

Patient-maintained propofol sedation (PMPS) is the delivery of procedural propofol sedation by target-controlled infusion with the patient exerting an element of control over their target-site propofol concentration. This scoping review aims to establish the extent and nature of current knowledge regarding PMPS from both a clinical and technological perspective, thereby identifying knowledge gaps to guide future research. We searched MEDLINE, EMBASE, and OpenGrey databases, identifying 17 clinical studies for analysis. PMPS is described in the context of healthy volunteers and in orthopaedic, general surgical, dental, and endoscopic clinical settings. All studies used modifications to existing commercially-available infusion devices to achieve prototype systems capable of PMPS. The current literature precludes rigorous generalisable conclusions regarding the safety or comparative clinical effectiveness of PMPS, however cautious acknowledgement of efficacy in specific clinical settings is appropriate. Based on the existing literature, together with new standardised outcome reporting recommendations for sedation research and frameworks designed to assess novel health technologies research, we have made recommendations for future pharmacological, clinical, behavioural, and health economic research on PMPS. We conclude that high-quality experimental clinical trials with relevant comparator groups assessing the impact of PMPS on standardised patient-orientated outcome measures are urgently required.

An analysis of the academic capacity of anaesthesia in the UK by publication trends and academic units

Over a decade ago, bibliometric analysis predicted the disappearance of UK publishing in anaesthesia by 2020. We repeated this analysis to assess if this had turned out to be the case, searching PubMed for papers associated with UK consultant anaesthetists for 2017-2019 across 15 journals. Although the rate of decline has flattened using the same search filter, including a wider range of publication types shows that outputs still remain at half 1990s levels (381 papers for all 3 years combined), authored by 769 anaesthetists, 274 of whom are associated with an academic centre. There are now 11 identifiable academic units, and a further 15 places where anaesthetists have affiliations with academic centres as individuals. The majority of papers (71%) are in secondary analysis (observational, database and association studies, surveys and meta-analyses), rather than in primary research (clinical trials or laboratory studies). These data reflect the current academic capacity in terms of publications, academic units and staffing. We discuss how this information can be used to inform a new strategy for UK academic anaesthesia.

Early Childhood General Anesthesia and Neurodevelopmental Outcomes in the Avon Longitudinal Study of Parents and Children Birth Cohort

Background

Most common anesthetic agents have been implicated in causing neurodegeneration in the developing animal brain, leading to warnings regarding their use in children. The hypothesis of this study was that exposure to general anesthesia and surgery before 4 yr would associate with adverse neurodevelopmental outcomes at age 7 to 16 yr.

Methods

This cohort study comprised 13,433 children enrolled in the Avon Longitudinal Study of Parents and Children, a prospective, population-based birth cohort born between 1991 and 1993 in southwest England. Children were grouped by none, single, or multiple exposures to general anesthesia and surgery by 4 yr. Motor, cognitive, linguistic, educational, social, and behavioral developmental outcomes were evaluated at 7 to 16 yr using school examination results, validated parent/teacher questionnaires, or clinic assessments. Continuous outcomes were z-scored. P-value thresholds were corrected using false discovery rate procedures.

Results

This study compared 46 neurodevelopmental outcomes in 13,433 children: 8.3% (1,110) exposed singly and 1.6% (212) exposed multiply to general anesthesia and surgery. Of these, the following reached predefined levels of statistical significance (corrected P &lt; 0.00652): dynamic balance scores were 0.3 SD (95% CI, 0.1, 0.5; P &lt; 0.001) lower in multiply exposed children; manual dexterity performance was 0.1 SD (95% CI, 0.0, 0.2; P = 0.006) lower in singly and 0.3 SD (95% CI, 0.1, 0.4; P &lt; 0.001) lower in multiply exposed children; and social communication scores were 0.1 SD (95% CI, 0.0, 0.2; P = 0.001) and 0.4 SD (95% CI, 0.3, 0.5; P &lt; 0.001) lower in singly and multiply exposed children, respectively. General anesthesia and surgery were not associated with impairments in the remaining neurodevelopmental measures including: general cognitive ability; attention; working memory; reading, spelling, verbal comprehension and expression; behavioral difficulties; or national English, mathematics, and science assessments (all ≤0.1 SD; corrected P ≥ 0.00652).

Conclusions

Early childhood general anesthesia and surgery were not associated with a global picture of clinically and statistically significant neurodegenerative effects, providing reassurance about the neurotoxic potential of general anesthesia. Exposure to anesthesia and surgery was associated with significantly lower motor and social linguistic performance.

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Competitive Interactions between Halothane and Isoflurane at the Carotid Body and TASK Channels

Background

The degree to which different volatile anesthetics depress carotid body hypoxic response relates to their ability to activate TASK potassium channels. Most commonly, volatile anesthetic pairs act additively at their molecular targets. We examined whether this applied to carotid body TASK channels.

Methods

We studied halothane and isoflurane effects on hypoxia-evoked rise in intracellular calcium (Ca2+i, using the indicator Indo-1) in isolated neonatal rat glomus cells, and TASK single-channel activity (patch clamping) in native glomus cells and HEK293 cell line cells transiently expressing TASK-1.

Results

Halothane (5%) depressed glomus cell Ca2+i hypoxic response (mean ± SD, 94 ± 4% depression; P &lt; 0.001 vs. control). Isoflurane (5%) had a less pronounced effect (53 ± 10% depression; P &lt; 0.001 vs. halothane). A mix of 3% isoflurane/1.5% halothane depressed cell Ca2+i response (51 ± 17% depression) to a lesser degree than 1.5% halothane alone (79 ± 15%; P = 0.001), but similar to 3% isoflurane alone (44 ± 22%; P = 0.224), indicating subadditivity. Halothane and isoflurane increased glomus cell TASK-1/TASK-3 activity, but mixes had a lesser effect than that seen with halothane alone: 4% halothane/4% isoflurane yielded channel open probabilities 127 ± 55% above control, versus 226 ± 12% for 4% halothane alone (P = 0.009). Finally, in HEK293 cell line cells, progressively adding isoflurane (1.5 to 5%) to halothane (2.5%) reduced TASK-1 channel activity from 120 ± 38% above control, to 88 ± 48% (P = 0.034).

Conclusions

In all three experimental models, the effects of isoflurane and halothane combinations were quantitatively consistent with the modeling of weak and strong agonists competing at a common receptor on the TASK channel.

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A deadly trend in fentanyl fatalities (England, 1998-2017)

AIM

To identify trends in drug-related deaths associated with fentanyl and its derivatives, including novel variants, in England, 1998-2017.

METHODS

Case reports from the National Programme on Substance Abuse Deaths (NPSAD) where a pharmaceutical fentanyl or non-pharmaceutical fentanyl derivative (NPFD) was found at post-mortem and/or implicated in the death were extracted for analysis.

RESULTS

NPSAD has received case reports detailing 298 deaths in England from 1998-2017 where a fentanyl was found at post-mortem and/or implicated in the death. Hospital administered fentanyl is "very safe", whereas pharmaceutical fentanyls in the community, procured either legitimately via prescription or illegitimately, carry high risk of unintentional death. Deaths involving NPFDs, which possess extreme potencies in comparison to morphine, have drastically risen over the past three years, and correlate with an increasing number of available compounds. Males, and those with existing opioid abuse disorders, are particularly susceptible to death related to NPFD intake.

CONCLUSIONS

The increasing availability of both pharmaceutical fentanyls and NPFDs represents a serious risk to public health. Unintentional misuse of these compounds in England is contributing to the exponential increase in fentanyl-associated deaths that is being observed at the global scale.

Assessing Long-term Neurodevelopmental Outcome Following General Anesthesia in Early Childhood: Challenges and Opportunities

Neurodegeneration has been reported in young animals after exposure to all commonly used general anesthetic agents. The brain may be particularly vulnerable to anesthetic toxicity during peak synaptogenesis (in gestation and infancy). Human studies of long-term neurodevelopmental outcome following general anesthesia in early childhood report contradictory findings. This review assesses the strengths and deficiencies in human research methodologies to inform future studies. We identified 76 studies, published between 1990 and 2017, of long-term neurodevelopmental outcome following early childhood or in utero general anesthesia exposure: 49 retrospective, 9 ambidirectional, 17 prospective cohort studies, and 1 randomized controlled trial. Forty-nine studies were explicitly concerned with anesthetic-induced neurotoxicity. Full texts were appraised for methodological challenges and possible solutions. Major challenges identified included delineating effects of anesthesia from surgery, defining the timing and duration of exposure, selection of a surgical cohort and intervention, addressing multiple confounding life course factors, detecting modest neurotoxic effects with small sample sizes (median, 131 children; interquartile range, 50–372), selection of sensitive neurodevelopmental outcomes at appropriate ages for different developmental domains, insufficient length of follow-up (median age, 6 years; interquartile range, 2–12 years), and sample attrition. We discuss potential solutions to these challenges. Further adequately powered, multicenter, prospective randomized controlled trials of anesthetic-induced neurotoxicity in children are required. However, we believe that the inherent methodological challenges of studying anesthetic-induced neurotoxicity necessitate the parallel use of well-designed observational cohort studies.

A mixed-methods pilot study to evaluate a collaborative anaesthetic and surgical training package for emergency surgical cricothyroidotomy

In a ‘can’t intubate, can’t oxygenate’ scenario, success of emergency front-of-neck access is dependent upon a clinician’s skill, competence and confidence to initiate the procedure. Surgical cricothyroidotomy is an important airway skill, as it can be employed as both the primary method of emergency front-of-neck access or as a rescue approach if a needle technique should fail. We designed a collaborative surgical and anaesthetic training package to address perceived anaesthetic reluctance to perform surgical cricothyroidotomy and undertook a pilot study of the package using a mixed-methods approach. The package consisted of three elements: theory teaching, surgical experience and repeated high-fidelity simulation. Ten anaesthetic trainees were trained using the package. Training comprised face-to-face tuition on the 2015 Difficult Airway Society guidelines, the Vortex cognitive aid, manikin-based surgical cricothyroidotomy instruction and surgical experience gained from an elective surgical tracheostomy. A standardised, high-fidelity in situ ‘can’t intubate, can’t oxygenate’ simulation was used to assess performance at baseline and at two weeks and six months after training. Participants scored their self-efficacy, underwent qualitative semi-structured interviews and had their performance quantitatively assessed to evaluate this training. Six months following training, participants’ performance had improved. They reported significantly increased self-efficacy and demonstrated significantly reduced deliberation time to initiate surgical cricothyroidotomy in the simulated ‘can’t intubate, can’t oxygenate’ emergency. Thematic framework analysis of interview transcripts revealed that reluctance to perform surgical cricothyroidotomy was related to fear and anxiety in regard to performing the procedure. These results support wider adoption of collaborative educational training packages, including hands-on surgical teaching, to improve trainees’ efficacy and confidence with surgical cricothyroidotomy and front-of-neck access in an emergency ‘can’t intubate, can’t oxygenate’ scenario.

A Prototype Patient-Maintained Propofol Sedation System Using Target Controlled Infusion for Primary Lower-Limb Arthroplasty

Each year, many operations in the UK are performed with the patient awake, without the use of general anaesthesia. These include joint replacement procedures, and in order to reduce patient anxiety, the supervising anaesthetist delivers the sedative propofol intravenously using a target-controlled infusion (TCI) device. However, it is clinically challenging to judge the required effect-site concentration of sedative for an individual patient, resulting in patient care issues related to over or under-sedation. To improve the process, patient-maintained propofol sedation (PMPS), where the patient can request an increase in concentration through a hand-held button, has been considered as an alternative. However, due to the proprietary nature of modern TCI pumps, the majority of PMPS research has been conducted using prototypes in research studies. In this work, a PMPS system is presented that effectively converts a standard infusion pump into a TCI device using a laptop with TCI software. Functionally, the system delivers sedation analogous to a modern TCI pump, with the differences in propofol consumption and dosage within the tolerance of clinically approved devices. Therefore, the Medicines and Healthcare products Regulatory Agency (MHRA) has approved the system as a safe alternative to anaesthetist-controlled TCI procedures. It represents a step forward in the consideration of PMPS as a sedation method as viable alternative, allowing further assessment in clinical trials.

Surgical safety in radical cystectomy: the anesthetist's point of view-how to make a safe procedure safer

PURPOSE

The aim of this review is to present an anesthesiological overview on surgical safety for radical cystectomy implementing the cornerstones of today's rapidly evolving field of perioperative medicine.

METHODS

This is a narrative review of current perioperative medicine and surgical safety concepts for major surgery in general with special focus on radical cystectomy.

RESULTS

The tendency for perioperative care and surgical safety is to consider it a continuous proactive pathway rather than a single surgical intervention. It starts at indication for surgery and lasts until full functional recovery. Preoperative optimization leads to superior outcome by mobilizing and/or increasing physiological reserve. Multidisciplinary teamwork involving all the relevant parties from the beginning of the pathway is crucial for outcome rather than an isolated specialist approach. This fact has gained importance in times of an ageing frail population and rising health care cost. We also present our 2019 Cystectomy Enhanced Recovery Approach for optimization of perioperative care for open radical cystectomy in a high caseload center.

CONCLUSIONS

With the implementation of in itself simple but crucial steps in perioperative medicine such as multimodal prehabilitation, safety checks, better perioperative monitoring and enhanced recovery concepts, even complex surgical procedures such as radical cystectomy can be performed safer. Emphasis has to be laid on a more global view of the patients' path through the perioperative process than on the surgical procedure alone.

Association between anaesthetic technique and unplanned admission to intensive care after thoracic lung resection surgery: the second Association of Cardiothoracic Anaesthesia and Critical Care (ACTACC) National Audit

Unplanned intensive care admission is a devastating complication of lung resection and is associated with significantly increased mortality. We carried out a two-year retrospective national multicentre cohort study to investigate the influence of anaesthetic and analgesic technique on the need for unplanned postoperative intensive care admission. All patients undergoing lung resection surgery in 16 thoracic surgical centres in the UK in the calendar years 2013 and 2014 were included. We defined critical care admission as the unplanned need for either tracheal intubation and mechanical ventilation or renal replacement therapy, and sought an association between mode of anaesthesia (total intravenous anaesthesia vs. volatile) and analgesic technique (epidural vs. paravertebral) and need for intensive care admission. A total of 253 out of 11,208 patients undergoing lung resection in the study period had an unplanned admission to intensive care in the postoperative period, giving an incidence of intensive care unit admission of 2.3% (95%CI 2.0-2.6%). Patients who had an unplanned admission to intensive care unit had a higher mortality (29.00% vs. 0.03%, p < 0.001), and hospital length of stay was increased (26 vs. 6 days, p < 0.001). Across univariate, complete case and multiple imputation (multivariate) models, there was a strong and significant effect of both anaesthetic and analgesic technique on the need for intensive care admission. Patients receiving total intravenous anaesthesia (OR 0.50 (95%CI 0.34-0.70)), and patients receiving epidural analgesia (OR 0.56 (95%CI 0.41-0.78)) were less likely to have an unplanned admission to intensive care after thoracic surgery. This large retrospective study suggests a significant effect of both anaesthetic and analgesic technique on outcome in patients undergoing lung resection. We must emphasise that the observed association does not directly imply causation, and suggest that well-conducted, large-scale randomised controlled trials are required to address these fundamental questions.

Accidental awareness during general anaesthesia - a narrative review

Unintended accidental awareness during general anaesthesia represents failure of successful anaesthesia, and so has been the subject of numerous studies during the past decades. As return to consciousness is both difficult to describe and identify, the reported incidence rates vary widely. Similarly, a wide range of techniques have been employed to identify cases of accidental awareness. Studies which have used the isolated forearm technique to identify responsiveness to command during intended anaesthesia have shown remarkably high incidences of awareness. For example, the ConsCIOUS-1 study showed an incidence of responsiveness around the time of laryngoscopy of 1:25. On the other hand, the 5th Royal College of Anaesthetists National Audit Project, which reported the largest ever cohort of patients who had experienced accidental awareness, used a system to identify patients who spontaneously self-reported accidental awareness. In this latter study, the incidence of accidental awareness was 1:19,600. In the recently published SNAP-1 observational study, in which structured postoperative interviews were performed, the incidence was 1:800. In almost all reported cases of intra-operative responsiveness, there was no subsequent explicit recall of intra-operative events. To date, there is no evidence that this occurrence has any psychological consequences. Among patients who experience accidental awareness and can later remember details of their experience, the consequences are better known. In particular, when awareness occurs in a patient who has been given neuromuscular blocking agents, it may result in serious sequelae such as symptoms of post-traumatic stress disorder and a permanent aversion to surgery and anaesthesia, and is feared by patients and anaesthetists. In this article, the published literature on the incidence, consequences and management of accidental awareness under general anaesthesia with subsequent recall will be reviewed.

Patient reported outcome of adult perioperative anaesthesia in the United Kingdom: a cross-sectional observational study

BACKGROUND

Understanding the patient perspective on healthcare is central to the evaluation of quality. This study measured selected patient-reported outcomes after anaesthesia in order to identify targets for research and quality improvement.

METHODS

This cross-sectional observational study in UK National Health Service hospitals, recruited adults undergoing non-obstetric surgery requiring anaesthesia care over a 48 h period. Within 24 h of surgery, patients completed the Bauer questionnaire (measuring postoperative discomfort and satisfaction with anaesthesia care), and a modified Brice questionnaire to elicit symptoms suggestive of accidental awareness during general anaesthesia (AAGA). Patient, procedural and pharmacological data were recorded to enable exploration of risk factors for these poor outcomes.

RESULTS

257 hospitals in 171 NHS Trusts participated (97% of eligible organisations). Baseline characteristics were collected on 16,222 patients; 15,040 (93%) completed postoperative questionnaires. Anxiety was most frequently cited as the worst aspect of the perioperative experience. Thirty-five per cent of patients reported severe discomfort in at least one domain: thirst (18.5%; 95% CI 17.8-19.1), surgical pain (11.0%; 10.5-11.5) and drowsiness (10.1%; 9.6-10.5) were most common. Despite this, only 5% reported dissatisfaction with any aspect of anaesthesia-related care. Regional anaesthesia was associated with a reduced burden of side-effects. The incidence of reported AAGA was one in 800 general anaesthetics (0.12%)

CONCLUSIONS

Anxiety and discomfort after surgery are common; despite this, satisfaction with anaesthesia care in the UK is high. The inconsistent relationship between patient-reported outcome, patient experience and patient satisfaction supports using all three of these domains to provide a comprehensive assessment of the quality of anaesthesia care.

Intraoperative oxygenation in adult patients undergoing surgery (iOPS): a retrospective observational study across 29 UK hospitals

Background

Considerable controversy remains about how much oxygen patients should receive during surgery. The 2016 World Health Organization (WHO) guidelines recommend that intubated patients receive a fractional inspired oxygen concentration (FIO₂) of 0.8 throughout abdominal surgery to reduce the risk of surgical site infection. However, this recommendation has been widely criticised by anaesthetists and evidence from other clinical contexts has suggested that giving a high concentration of oxygen might worsen patient outcomes. This retrospective multi-centre observational study aimed to ascertain intraoperative oxygen administration practice by anaesthetists across parts of the UK.

Methods

Patients undergoing general anaesthesia with an arterial catheter in situ across hospitals affiliated with two anaesthetic trainee audit networks (PLAN, SPARC) were eligible for inclusion unless undergoing cardiopulmonary bypass. Demographic and intraoperative oxygenation data, haemoglobin saturation and positive end-expiratory pressure were retrieved from anaesthetic charts and arterial blood gases (ABGs) over five consecutive weekdays in April and May 2017.

Results

Three hundred seventy-eight patients from 29 hospitals were included. Median age was 66 years, 205 (54.2%) were male and median ASA grade was 3. One hundred eight (28.6%) were emergency cases. An anticipated difficult airway or raised BMI was documented preoperatively in 31 (8.2%) and 45 (11.9%) respectively. Respiratory or cardiac comorbidity was documented in 103 (27%) and 83 (22%) respectively. SpO₂ < 96% was documented in 83 (22%) patients, with 7 (1.9%) patients desaturating < 88% at any point intraoperatively. The intraoperative FIO₂ ranged from 0.25 to 1.0, and median PaO₂/FIO₂ ratios for the first four arterial blood gases taken in each case were 24.6/0.5, 23.4/0.49, 25.7/0.46 and 25.4/0.47 respectively.

Conclusions

Intraoperative oxygenation currently varies widely. An intraoperative FIO₂ of 0.5 currently represents standard intraoperative practice in the UK, with surgical patients often experiencing moderate levels of hyperoxaemia. This differs from both WHO’s recommendation of using an FIO₂ of 0.8 intraoperatively, and also, the value most previous interventional oxygen therapy trials have used to represent standard care (typically FIO₂ = 0.3). These findings should be used to aid the design of future intraoperative oxygen studies.