Supraglottic Airway Devices: Present State and Outlook for 2050.

Correct placement of supraglottic airway devices (SGDs) is crucial for patient safety and of prime concern of anesthesiologists who want to provide effective and efficient airway management to their patients undergoing surgery or procedures requiring anesthesia care. In the majority of cases, blind insertion of SGDs results in less-than-optimal anatomical and functional positioning of the airway devices. Malpositioning can cause clinical malfunction and result in interference with gas exchange, loss-of-airway, gastric inflation, and aspiration of gastric contents. A close match is needed between the shape and profile of SGDs and the laryngeal inlet. An adequate first seal (with the respiratory tract) and a good fit at the second seal of the distal cuff and the gastrointestinal tract are most desirable. Vision-guided insertion techniques are ideal and should be the way forward. This article recommends the use of third-generation vision-incorporated-video SGDs, which allow for direct visualization of the insertion process, corrective maneuvers, and, when necessary, insertion of a nasogastric tube (NGT) and/or endotracheal tube (ETT) intubation. A videoscope embedded within the SGD allows a visual check of the glottis opening and position of the epiglottis. This design affords the benefit of confirming and/or correcting a SGD's position in the midline and rotation in the sagittal plane. The first clinically available video laryngeal mask airways (VLMAs) and multiple prototypes are being tested and used in anesthesia. Existing VLMAs are still not perfect, and further improvements are recommended. Additional modifications in multicamera technology, to obtain a panoramic view of the SGD sitting correctly in the hypopharynx and to prove that correct sizes have been used, are in the process of production. Ultimately, any device inserted orally-SGD, ETT, NGT, temperature probe, transesophageal scope, neural integrity monitor (NIM) tubes-could benefit from correct vision-guided positioning. VLMAs also allow for automatic recording, which can be documented in clinical records of patients, and could be valuable during teaching and research, with potential value in case of legal defence (with an airway incident). If difficulties occur with the airway, documentation in the patient's file may help future anesthesiologists to better understand the real-time problems. Both manufacturers and designers of SGDs may learn from optimally positioned SGDs to improve the design of these airway devices.

Getting operating theatre metrics right to underpin quality improvement: understanding limitations of NHS Model Hospital calculations.

The Model Hospital is an NHS online resource summarising performance data for, amongst other things, operating theatres categorised by NHS Trust and specialty. As an official source of information, it might be assumed that metrics, such as 'average late start time', 'average early finish time', and 'average late finish time', are calculated in a way to reflect performance in these domains, but this is not the case. These values are, respectively, only for those lists that start late, finish early, and finish late, with the number of lists in each category unreported. The Model Hospital reports utilisation appropriately as 'touch time' (the time delivering anaesthesia and surgery) but prefers a 'capped' measure, in which any touch time occurring in late finishes is ignored. The Model Hospital aggregates utilisations across lists in a mathematically invalid way, which leads to the assumption that small aliquots of unused time on lists can be combined to create larger time blocks, in which to complete more operations. We present alternative, more intuitive, and mathematically conventional methods to derive performance metrics using the same data. The results have implications for hospitals developing their own dashboards and international organisations seeking to create national databases for operating theatre performance.

Multivariable Cost Frontiers-Qualitative Financial Analyses Using Operational Metrics From the Implementation of a Surgery Fellowship.

OBJECTIVE: We expand the application of cost frontiers and introduce a novel approach using qualitative multivariable financial analyses. SUMMARY BACKGROUND DATA: With the creation of a 5 + 2-year fellowship program in July 2016, the Division of Vascular Surgery at the University of Vermont Medical Center altered the underlying operational structure of its inpatient services. METHOD: Using WiseOR (Palo Alto, CA), a web-based OR management data system, we extracted the operating room metrics before and after August 1, 2016 service for each 4-week period spanning from September 2015 to July 2017. The cost per minute modeled after Childers et al's inpatient OR cost guidelines was multiplied by the after-hours utilization to determine variable cost. Zones with corresponding cutoffs were used to graphically represent cost efficiency trends. RESULTS: Caseload/FTE for attending surgeons increased from 11.54 cases per month to 13.02 cases per month ( P = 0.0771). Monthly variable costs/FTE increased from $540.2 to $1873 ( P = 0.0138). Monthly revenue/FTE increased from $61,505 to $70,277 ( P = 0.2639). Adjusted monthly reve-nue/FTE increased from $60,965 to $68,403 ( P = 0.3374). Average monthly percent of adjusted revenue/FTE lost to variable costs increased from 0.85% to 2.77% ( P = 0.0078). Adjusted monthly revenue/case/FTE remained the same from $5309 to $5319 ( P = 0.9889). CONCLUSION: In summary, we demonstrate that multivariable cost (or performance) frontiers can track a net increase in profitability associated with fellowship implementation despite diminishing returns at higher caseloads.

A graphical assessment of emergency surgical list efficiency to determine operating theatre capacity needs.

BACKGROUND: Unlike elective lists, full utilisation of an emergency list is undesirable, as it could prevent patient access. Conversely, a perpetually empty emergency theatre is resource wasteful. Separately, measuring delayed access to emergency surgery from time of booking the urgent case is relevant, and could reflect either deficiencies in patient preparation or be because of an occupied (over-utilised) emergency theatre. METHODS: We developed a graphical method recognising these two separate but linked elements of performance: (i) delayed access to surgery and (ii) operating theatre utilisation. In a plot of one against the other, data fell into one of four quadrants, with delays associated with high utilisation signifying the need for more emergency capacity. However, delays associated with low utilisation reflect process deficiencies in the emergency patient pathway. We applied this analysis to 73 consecutive lists (>300 cases) from two UK hospitals. RESULTS: Although both hospitals experienced similar rates of delayed surgery (21.8% vs 21.0%; P=0.872), in one hospital 83% of these were associated with low emergency theatre utilisation (suggesting predominant process deficiencies), whereas in the other 73% were associated with high utilisation (suggesting capacity deficiency; P<0.0001). Increasing emergency capacity in the latter resulted in shorter delays (just 6.7% cases excessively delayed; P<0.0001 for effect of intervention). CONCLUSIONS: This simple graphical analysis indicates whether more emergency capacity is necessary. We discuss potential applications in managing emergency surgery theatres.

The Power Law in Operating Room Management.

The Acute Care Surgery model has been implemented by many hospitals in the United States. As complex adaptive systems, healthcare systems are composed of many interacting elements that respond to intrinsic and extrinsic inputs. Systems level analysis may reveal the underlying organizational structure of tactical block allocations like the Acute Care Surgery model. The purpose of this study is to demonstrate one method to identify a key characteristic of complex adaptive systems in the perioperative services. Start and end times for all surgeries performed at the University of Vermont Medical Center OR1 were extracted for two years prior to the transition to an Acute Care Surgery service and two years following the transition. Histograms were plotted for the inter-event times calculated from the difference between surgical cases. A power law distribution was fit to the post-transition histogram. The Kolmogorov-Smirnov test for goodness-of-fit at 95% level of significance shows the histogram plotted from post-transition inter-event times follows a power law distribution (K-S = 0.088, p = 0.068), indicating a Complex Adaptive System. Our analysis demonstrates that the strategic decision to create an Acute Care Surgery service has direct implications on tactical and operational processes in the perioperative services. Elements of complex adaptive systems can be represented by a power law distributions and similar methods may be applied to identify other processes that operate as complex adaptive systems in perioperative care. To make sustained improvements in the perioperative services, focus on manufacturing-based interventions such as Lean Six Sigma should instead be shifted towards the complex interventions that modify system-specific behaviors described by complex adaptive system principles when power law relationships are present.

Monitoring Perioperative Services Using 3D Multi-Objective Performance Frontiers.

The Acute Care Surgery model has been widely adopted by hospitals across the United States, with Acute Care Surgery services managing Emergency General Surgery patients that were previously being treated by General Surgery. In this analysis, we evaluate the impact of an Acute Care Surgery service model on General Surgery at the University of Vermont Medical Center using three metrics: under-utilized time, spillover time, and a financial ratio of work Relative Value Units over clinical Full Time Equivalents. These metrics are evaluated and used to identify three-dimensional Pareto optimality of General Surgery prior to and after the October 2015 tactical allocation to the Acute Care Surgery model. Our analysis was further substantiated using a Markov Chain Monte Carlo model for Bayesian Inference. We applied multi-objective Pareto and Bayesian breakpoint analysis to three operating room metrics to assess the impact of new operating room management decisions. In the two-dimensional space of Fig. 2, panel a), the post-tactical allocation front lies closer to the origin representing more optimal solutions for productivity and under-utilized time. The post-tactical allocation front is also closer to the origin for productivity and spillover time as shown in the two-dimensional space of Fig. 2, panel b). The results of the three-dimensional multi-objective analysis of Fig. 3 illustrate that the GS post-tactical allocation Pareto-surface is contained within a much smaller volume of space than the GS pre-tactical allocation Pareto-surface. The post-tactical allocation Pareto-surface is slightly lower along the z-axis, representing lower productivity than the pre-tactical allocation surface. This methodology might contribute to the external benchmarking and monitoring of perioperative services by visualizing the operational implications following tactical decisions in operating room management.

Anesthesia and airway management for gastrointestinal endoscopic procedures outside the operating room.

PURPOSE OF REVIEW: To review the anesthestic and airway management for gastrointestinal procedures outside of the operating room. RECENT FINDINGS: The number of gastrointestinal endoscopic procedures performed is steadily increasing worldwide. As complexity, duration and invasiveness of procedures increase, there is ever greater requirement for deeper sedation or general anesthesia. A close relationship between anesthetic practitioners and endoscopists is required to ensure safe and successful outcomes. The American Society of Gastrointestinal endoscopy and the British Society of Gastroenterology have recently released guidelines for sedation and general anesthesia in gastrointestinal endoscopy, highlighting the need for careful monitoring for all cases, and anesthetic expertise in complex cases. The recent advances in high-flow nasal oxygenation in sedation may provide alternative options for oxygenation during gastrointestinal sedation, especially in deep sedation and this may reduce the need for general anesthesia. SUMMARY: The advances in gastrointestinal endoscopic intervention have increased the requirement for deep sedation and anesthetic involvement outside of the operating room. Careful titration of anesthetic intervention and close monitoring are required to ensure patient safety.

Retrospective observational evaluation of postoperative oxygen saturation levels and associated postoperative respiratory complications and hospital resource utilization.

INTRODUCTION: The clinical importance of postoperative episodic hypoxemia is still unclear, and therefore largely under-studied. As a result, there is limited understanding of its relationship with early postoperative respiratory complications (PRC, defined as intubation within three days of surgery) and hospital resource utilization. MATERIALS AND METHODS: This single center study was performed using a retrospective observational design. We described population based definitions of desaturation from continuous SpO2 monitoring data captured in the post anesthesia care unit (PACU), namely median SpO2 in PACU, duration of desaturation below median, nadir desaturation, and length of oxygen therapy relative to PACU duration. These measures were evaluated against the occurrence of early PRC in logistic regression models. Measures that were independently associated with early PRC were accepted as the primary study exposures. Stratified logistic regression models were planned if significant interaction occurred with high risk surgical procedures. Models were adjusted by including several patient conditions, procedural, and anesthesia risk factors. Propensity matching on desaturation occurrence was planned to evaluate the relationship with postoperative resource utilization. RESULTS: Among 125,740 patients included in the univariate analyses, 351 patients (0.3%) developed early PRC. Nadir desaturation <89% [14.3% of patients; adjusted odds ratio 2.02; 95% CI 1.52, 2.68; p<0.001] and PACU oxygen therapy requirements greater than 60 min [adjusted odds ratio 1.92 (>60 min) to 3.04 (>90 min); p<0.001] were identified as independent predictors of early PRC occurrence. A modest interaction was observed between desaturation and higher surgical risk. Propensity matching for postoperative oxygen requirement was performed in 37,354 matched patients. Matched analysis demonstrated significant increase in day of surgery charges, respiratory charges, total charges, hospital length of stay, reintubation and use of invasive or non-invasive ventilatory support. CONCLUSIONS: In summary, we report that prolonged PACU oxygen therapy and nadir desaturation <89% in PACU as captured in a retrospective database are independently associated with early PRC. This study describes resource implications of PACU desaturation in a large academic medical center in North America.

The state of UK pediatric anesthesia: a survey of National Health Service activity.

This secondary analysis of the 2013 United Kingdom National Health Service (NHS) Anaesthesia Activity Survey of the Fifth National Audit Project (of the Royal College of Anaesthetists and Association of Anaesthetists of Great Britain and Ireland) shows pediatric anesthesia activity in detail. A local coordinator (LC) in every NHS hospital collected data on patients undergoing any procedure managed by an anesthetist. Questionnaires had 30 question categories. Each LC was randomized to a 2-day period. The pediatric age groups were infants, (<1 year), preschool age (1-5 year), and school age children (6-15 year). The median questionnaire return rate was 98%. The annual caseload was estimated to be 486 900 children: 36 500 infants, 184 700 preschool age, and 265 800 school age children. Almost 90% of children (1-15 year) were ASA 1 or 2 and the substantial majority underwent routine nonurgent ear nose and throat, dental, orthopaedics, or general surgery procedures; 65% were 'day cases'. One in six children were managed outside operating theater sites compared with one in 12 adults. Forty one per cent was in district general hospitals. Almost all ASA 4 and 5 children (89%) and infants (92%) were managed in specialist hospitals. 'Awake' cases and sedation accounted for only 2% of cases. There were notable differences in demography and anesthetic care compared with adults and between different age groups of children. These data enable analysis of the current state of UK pediatric anesthetic practice and highlight differences between pediatric and adult services.

Does amifostine reduce metabolic rate? Effect of the drug on gas exchange and acute ventilatory hypoxic response in humans.

Amifostine is added to chemoradiation regimens in the treatment of many cancers on the basis that, by reducing the metabolic rate, it protects normal cells from toxic effects of therapy. We tested this hypothesis by measuring the metabolic rate (by gas exchange) over 255 min in 6 healthy subjects, at two doses (500 mg and 1000 mg) of amifostine infused over 15 min at the start of the protocol. We also assessed the ventilatory response to six 1 min exposures to isocapnic hypoxia mid-protocol. There was no change in metabolic rate with amifostine as measured by oxygen uptake (p = 0.113). However in carbon dioxide output and respiratory quotient, we detected a small decline over time in control and drug protocols, consistent with a gradual change from carbohydrate to fat metabolism over the course of the relatively long study protocol. A novel result was that amifostine (1000 mg) increased the mean ± SD acute hypoxic ventilatory response from 12.4 ± 5.1 L/min to 20.3 ± 11.9 L/min (p = 0.045). In conclusion, any cellular protective effects of amifostine are unlikely due to metabolic effects. The stimulatory effect on hypoxic ventilatory responses may be due to increased levels of hypoxia inducible factor, either peripherally in the carotid body, or centrally in the brain.

Acceptably aware during general anaesthesia: 'dysanaesthesia'--the uncoupling of perception from sensory inputs.

This review makes the case for 'dysanaesthesia', a term encompassing states of mind that can arise in the course of anaesthesia during surgery, characterised by an uncoupling of sensation and perceptual experience. This is reflected in a macroscopic, functional model of anaesthetically-relevant consciousness. Patients in this state can be aware of events but in a neutral way, not in pain, sometimes personally dissociated from the experiences. This makes events associated with surgery peripheral to their whole experience, such that recall is less likely and if it exists, makes any spontaneous report of awareness unlikely. This state of perception-sensation uncoupling is therefore broadly acceptable (a minimum requirement for acceptable anaesthesia) but since it is likely a dose-related phenomenon, may also represent a precursor for awareness with adverse recall. This hypothesis uniquely explains the often inconsistent responses seen during the experimental paradigm of the 'isolated forearm technique', wherein apparently anaesthetised patients exhibit a positive motor response to verbal command, but no spontaneous movement to surgery. The hypothesis can also explain the relatively high incidence of positive response to relatively direct questions for recall (e.g., using the Brice questionnaire; ∼1:500; the vast majority of these being neutral reports) versus the very low incidence of spontaneous reports of awareness (∼1:15,000; a higher proportion of these being adverse recollections). The hypothesis is consistent with relevant notions from philosophical discussions of consciousness, and neuroscientific evidence. Dysanaesthesia has important implications for research and also for the development of appropriate monitoring.

Matching surgical operating capacity to demand using estimates of operating times.

PURPOSE: This paper sets out to investigate whether demand for gynaecological theatre time could be described in terms of the time required to undertake elective operations booked for surgery, and so help match the capacity to this. DESIGN/METHODOLOGY/APPROACH: A questionnaire assessed the estimates for total operation time for seven common operations, sent to surgeons, anaesthetists and nursing staff in one tertiary referral and one district general hospital (total 49 staff; response rate 58 per cent), and estimates were obtained from theatre computer logs. Average timings for each operation were then applied to cases added from clinics to the waiting list at the district general, to yield the mean demand for elective surgery, and were also applied to emergencies to estimate emergency workload. Finally these demand estimates were compared with the theatre capacity available. FINDINGS: The paper found no difference between the estimates of the three staff groups or between these and the theatre logs (p = 0.669), nor did it find that estimates differed between the two centers (p = 0.628). Including emergencies, the mean (95 per cent confidence intervals) demand at the district general was 2438 (1952-2924) min/week. RESEARCH LIMITATIONS/IMPLICATIONS: Although the paper modelled the variation in demand using the relevant variation in operation times, any additional variation caused by differences in booking rates from clinics over time was not nodelled. The minimum period over which data should be collected was not established. PRACTICAL IMPLICATIONS: The paper finds that the existing capacity of 1680 min/week did not match these needs and, unless it was increased, a rise in waiting lists was predictable. ORIGINALITY/VALUE: The paper concludes that time estimates for scheduled operations can be better used to assess the need for surgical operating capacity than current measures of demand or capacity.