Perioperative medicine training resources: U2M7: Surgical planning

This document has been written to assist in the identification and perioperative management of the adult higher risk patients with an acute surgical abdomen requiring emergency surgery, drawing on recent guidance from the Royal College of Surgeons and the Association of Surgeons of Great Britain and Ireland.

Abstract
Background: The average age of the surgical population continues to increase, as does prevalence of long-term diseases. However, outcomes amongst multi-morbid surgical patients are not well described.

Methods: We included adults undergoing non-obstetric surgical procedures in the English National Health Service between January 2010 and December 2015. Patients could be included multiple times in sequential 90-day procedure spells. Multi-morbidity was defined as presence of two or more long-term diseases identified using a modified Charlson comorbidity index. The primary outcome was 90-day postoperative death. Secondary outcomes included emergency hospital readmission within 90 days. We calculated age- and sex-adjusted odds ratios (OR) with 95% confidence intervals (CI) using logistic regression. We compared the outcomes associated with different disease combinations.

Results: We identified 20 193 659 procedure spells among 13 062 715 individuals aged 57 (standard deviation 19) yr. Multi-morbidity was present among 2 577 049 (12.8%) spells with 195 965 deaths (7.6%), compared with 17 616 610 (88.2%) spells without multi-morbidity with 163 529 deaths (0.9%). Multi-morbidity was present in 1 902 859/16 946 808 (11.2%) elective spells, with 57 663 deaths (2.7%, OR 4.9 [95% CI: 4.9-4.9]), and 674 190/3 246 851 (20.7%) non-elective spells, with 138 302 deaths (20.5%, OR 3.0 [95% CI: 3.0-3.1]). Emergency readmission followed 547 399 (22.0%) spells with multi-morbidity compared with 1 255 526 (7.2%) without. Multi-morbid patients accounted for 57 663/114 783 (50.2%) deaths after elective spells, and 138 302/244 711 (56.5%) after non-elective spells. The rate of death varied five-fold from lowest to highest risk disease pairs.

Conclusion: One in eight patients undergoing surgery have multi-morbidity, accounting for more than half of all postoperative deaths. Disease interactions amongst multi-morbid patients is an important determinant of patient outcome.

Abstract
A substantial number of patients are at high-risk of intra- or post-operative complications or both. Most perioperative deaths are represented by patients who present insufficient physiological reserve to meet the demands of major surgery. Recognition and management of critical high-risk surgical patients require dedicated and effective teams, capable of preventing, recognize, start treatment with adequate support in time to refer patients to the satisfactory ICU level provision. The main task for health-care planners and managers is to identify and reduce this severe risk and to encourage patient's safety practices. Inadequate tissue perfusion and decreased cellular oxygenation due to hypovolemia, heart dysfunction, reduced cardiovascular reserve, and concomitant diseases are the most common causes of perioperative complications. Hemodynamic, respiratory and careful sequential monitoring have become essential aspects of the clinical practice both for surgeons and intensivists. New monitoring techniques have changed significantly over the past few years and are now able to rapidly identify shock states earlier, define the etiology, and monitor the response to different therapies. Many of these techniques are now minimally invasive or non-invasive. Advanced hemodynamic and respiratory monitoring combines invasive, non-invasive monitoring skills. Non-invasive ultrasound has emerged during the last years as an essential operative and perioperative evaluation tool, and its use is now rapidly growing. Perioperative management guided by appropriate sequential clinical evaluation combined with respiratory and hemodynamic monitoring is an established tool to help clinicians to identify those patients at higher risk in the attempt to reduce the complications rate and potentially improve patient outcomes. This review aims to provide an update of currently available standard concepts and evolving technologies of the various respiratory and hemodynamic monitoring systems for the high-risk surgical patients, highlighting their potential usefulness when integrated with careful clinical evaluation.

Abstract
To determine the effects of ranitidine and metoclopramide on gastric fluid in children, 40 healthy children (aged 2-8 yr) were allocated randomly to groups of 10 to receive one of four oral premedications 4 h before surgery: no premedication, metoclopramide 0.1 mg kg-1, ranitidine 2 mg kg-1 and metoclopramide 0.1 mg kg-1 with ranitidine 2 mg kg-1. After tracheal intubation, gastric fluid was aspirated and analysed for pH and total fluid volume. Ranitidine, with or without metoclopramide, increased gastric fluid pH significantly compared with control (P less than 0.05). Gastric fluid volume did not change significantly.

Abstract
Purpose of review: Timely identification of high-risk surgical candidates facilitate surgical decision-making and allows appropriate tailoring of perioperative management strategies. This review aims to summarize the recent advances in perioperative risk stratification.

Recent findings: Use of indices which include various combinations of preoperative and postoperative variables remain the most commonly used risk-stratification strategy. Incorporation of biomarkers (troponin and natriuretic peptides), comprehensive objective assessment of functional capacity, and frailty into the current framework enhance perioperative risk estimation. Intraoperative hemodynamic parameters can provide further signals towards identifying patients at risk of adverse postoperative outcomes. Implementation of machine-learning algorithms is showing promising results in real-time forecasting of perioperative outcomes.

Summary: Perioperative risk estimation is multidimensional including validated indices, biomarkers, functional capacity estimation, and intraoperative hemodynamics. Identification and implementation of targeted strategies which mitigate predicted risk remains a greater challenge.

Abstract
The Guidelines to the Practice of Anesthesia Revised Edition 2018 (the Guidelines) were prepared by the Canadian Anesthesiologists' Society (CAS), which reserves the right to determine their publication and distribution. The Guidelines are subject to revision and updated versions are published annually. The Guidelines to the Practice of Anesthesia Revised Edition 2018 supersedes all previously published versions of this document. Although the CAS encourages Canadian anesthesiologists to adhere to its practice guidelines to ensure high-quality patient care, the CAS cannot guarantee any specific patient outcome. Anesthesiologists should exercise their own professional judgement in determining the proper course of action for any patient's circumstances. The CAS assumes no responsibility or liability for any error or omission arising from the use of any information contained in its Guidelines to the Practice of Anesthesia.

Abstract
The purposes of this study were to use a noninvasive scintigraphic technique to measure gastric emptying of liquids and solids simultaneously, to study the interactions between emptying of the liquid and solid components of meals in normal subjects, and to employ dual isotope gastric scintigraphy to evaluate gastric emptying of liquids and solids in patients with clinical evidence of gastric outlet obstruction. The solid component of the test meal consisted of chicken liver, labeled in vivo with Tc-99m sulfur colloid, and the liquid component was water mixed with In-111 DTPA. The rates of emptying were quantitated using a gamma camera on line to a digital computer. Twenty normal subjects were studied using this combined solid-liquid meal. Ten of them also ingested a liquid meal alone and ten a solid meal alone. Liquid emptied from the stomach significantly more rapidly than did solids. The emptying curve for liquids was exponential compared to a linear emptying curve for solids. The gastric emptying rate of the liquid component was slowed significantly by simultaneous ingestion of solids, but the emptying rate of solids was not affected by liquids. Several patients with clinical gastric outlet obstruction were evaluated. Both combined and selective abnormalities for gastric emptying of liquids and solids were demonstrated.

Abstract
The amount and composition of gastrointestinal media are crucial parameters in oral drug delivery. In fasted state, variable residual gastric volumes and gastric emptying behavior often cause variable drug release and absorption from oral drug products. Unfortunately, interindividual and intraindividual variability of the gastric conditions in fasted state are currently insufficiently mapped. In this work, datasets from 5 MRI studies with 16 treatments in total were pooled. The interindividual and intraindividual variability of residual gastric volumes after 10 h overnight fasting and the subsequent emptying of 240 mL of water were compared in healthy human subjects under conditions mimicking clinical studies. This work shows that even under standardized clinical conditions, residual gastric volumes and water emptying are highly variable. Interestingly, interindividual and intraindividual variabilities of both parameters were comparable, suggesting that the variability within the studies was mainly resulting from intraindividual day-to-day variations. The mean resting volumes in all conducted investigations amounted to 25 ± 18 mL (n = 120). Furthermore, 85 ± 13% (n = 22) of initially available gastric volume (resting volume plus 240 mL) was emptied after 30 min. The findings of this work will hopefully contribute to a better comprehension of the variability of oral drug release and absorption.

Abstract
To evaluate the effect of volume of aspirates with different pHs on mortality associated with pulmonary aspiration, hydrochloric acid solutions were injected into the tracheas of 336 Sprague-Dawley rats. The rats were divided randomly into 33 groups, were observed for 96 hr after aspiration, and were not resuscitated. Deaths were divided into two groups: early, less than 30 min after aspiration, and late, greater than 4 hr after aspiration. Late deaths, accounting for 22% of all fatalities, occurred exclusively in animals aspirating solutions with a pH less than 2.5. These late deaths indicated progressive lung damage as opposed to acute cardiorespiratory failure, which early deaths suggested. Low volume pulmonary aspirates (0.3 ml/kg) with extremely low pH (1.0) resulted in a high mortality rate (90%). Conversely, higher volume pulmonary aspirates (1.0-2.0 ml/kg) with a higher pH (greater than or equal to 1.8) resulted in a low mortality rate (14%). These data demonstrate an important interaction between pH and volume of aspirates: even low volumes have a high mortality rate if pH is very low, whereas if gastric fluid is effectively buffered, then much higher volumes than previously thought can be tolerated. This suggests that the routine use of nonparticulate antacids may be indicated in patients at risk from aspiration of stomach contents and should not be withheld because of concern of increasing gastric volume.

Abstract
These practice guidelines are a modular update of the "Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: Application to healthy patients undergoing elective procedures." The guidance focuses on topics not addressed in the previous guideline: ingestion of carbohydrate-containing clear liquids with or without protein, chewing gum, and pediatric fasting duration.

Abstract
Importance: Enhanced Recovery After Surgery (ERAS) is a paradigm shift in perioperative care, resulting in substantial improvements in clinical outcomes and cost savings.

Observations: Enhanced Recovery After Surgery is a multimodal, multidisciplinary approach to the care of the surgical patient. Enhanced Recovery After Surgery process implementation involves a team consisting of surgeons, anesthetists, an ERAS coordinator (often a nurse or a physician assistant), and staff from units that care for the surgical patient. The care protocol is based on published evidence. The ERAS Society, an international nonprofit professional society that promotes, develops, and implements ERAS programs, publishes updated guidelines for many operations, such as evidence-based modern care changes from overnight fasting to carbohydrate drinks 2 hours before surgery, minimally invasive approaches instead of large incisions, management of fluids to seek balance rather than large volumes of intravenous fluids, avoidance of or early removal of drains and tubes, early mobilization, and serving of drinks and food the day of the operation. Enhanced Recovery After Surgery protocols have resulted in shorter length of hospital stay by 30% to 50% and similar reductions in complications, while readmissions and costs are reduced. The elements of the protocol reduce the stress of the operation to retain anabolic homeostasis. The ERAS Society conducts structured implementation programs that are currently in use in more than 20 countries. Local ERAS teams from hospitals are trained to implement ERAS processes. Audit of process compliance and patient outcomes are important features. Enhanced Recovery After Surgery started mainly with colorectal surgery but has been shown to improve outcomes in almost all major surgical specialties.

Conclusions and relevance: Enhanced Recovery After Surgery is an evidence-based care improvement process for surgical patients. Implementation of ERAS programs results in major improvements in clinical outcomes and cost, making ERAS an important example of value-based care applied to surgery.

Abstract
The purpose of this chapter is to review historical fasting guidelines and how the dogma of fasting from midnight arose and came to be challenged by randomized clinical trials of preoperative clear liquids versus overnight fast. Medical and anaesthesia textbooks and journals from the 19th and 20th centuries were consulted, and the results of clinical trials and the reaction to them are reviewed. The dogma appeared to result from extrapolation of pulmonary aspiration risk in 'full-stomach' emergency cases to healthy elective cases. This was reinforced when 25 mL in the stomach, present in half of all healthy fasting patients, was used as a surrogate marker for high risk of aspiration. Subsequent large-scale studies showed the risk to be minimal. Meta-analysis of randomized clinical trials demonstrated the safety of clear oral liquids until 2 hr preoperatively in healthy patients undergoing elective surgery. Reaction was cautious but led to eventual acceptance of evidence-based fasting guidelines.

Abstract
Introduction: The aim was to identify high-risk patients undergoing non-elective orthopaedic and general surgery.

Patients and methods: This was a retrospective cohort study of all non-elective general and orthopaedic surgical procedures performed in a 1-year interval in a district general hospital. A total of 1869 patients underwent urgent or emergency surgery in the calendar year 2000. Outcomes were identified from various related hospital databases. Case notes of those who died were reviewed. Risk factors for mortality were examined using univariate and multivariate analysis.

Results: The mortality rates were 89/1869 (5%) at 30 days and 216 (12%) after 1 year. The high initial death rate continued for about 100 days after surgery. Increasing age (P < 0.0001), size of operation (P = 0.004) and American Society of Anesthesiologists (ASA) fitness grade (P < 0.0001) were associated with significantly higher risk of death at 1 year on multivariate analysis. A high risk group was identified of 273 patients aged over 50 years, of ASA Grade III or above who needed major surgery; they had a 30-day mortality rate of 18%.

Conclusions: A simple scoring system could be used to identify high-risk patients who require non-elective surgery that could be a target for interventions to try and reduce their risk of death.

Abstract
Background: This is Part 3 of the first consensus guidelines for optimal care of patients undergoing emergency laparotomy using an enhanced recovery after surgery (ERAS) approach. This paper addresses organizational aspects of care.

Methods: Experts in management of the high-risk and emergency general surgical patient were invited to contribute by the International ERAS® Society. PubMed, Cochrane, Embase, and MEDLINE database searches were performed for ERAS elements and relevant specific topics. Studies were selected with particular attention to randomized clinical trials, systematic reviews, meta-analyses and large cohort studies, and reviewed and graded using the Grading of Recommendations, Assessment, Development and Evaluation system. Recommendations were made on the best level of evidence, or extrapolation from studies on elective patients when appropriate. A modified Delphi method was used to validate final recommendations.

Results: Components of organizational aspects of care were considered. Consensus was reached after three rounds of a modified Delphi process.

Conclusions: These guidelines are based on best current available evidence for organizational aspects of an ERAS® approach to patients undergoing emergency laparotomy and include discussion of less common aspects of care for the surgical patient, including end-of-life issues. These guidelines are not exhaustive but pull together evidence on important components of care for this high-risk patient population. As much of the evidence is extrapolated from elective surgery or emergency general surgery (not specifically laparotomy), many of the components need further evaluation in future studies.

Abstract
Background: Enhanced Recovery After Surgery (ERAS) protocols reduce length of stay, complications and costs for a large number of elective surgical procedures. A similar, structured approach appears to improve outcomes, including mortality, for patients undergoing high-risk emergency general surgery, and specifically emergency laparotomy. These are the first consensus guidelines for optimal care of these patients using an ERAS approach.

Methods: Experts in aspects of management of the high-risk and emergency general surgical patient were invited to contribute by the International ERAS® Society. Pubmed, Cochrane, Embase, and MEDLINE database searches on English language publications were performed for ERAS elements and relevant specific topics. Studies on each item were selected with particular attention to randomized controlled trials, systematic reviews, meta-analyses and large cohort studies, and reviewed and graded using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. Recommendations were made on the best level of evidence, or extrapolation from studies on non-emergency patients when appropriate. The Delphi method was used to validate final recommendations. The guideline has been divided into two parts: Part 1-Preoperative Care and Part 2-Intraoperative and Postoperative management. This paper provides guidelines for Part 1.

Results: Twelve components of preoperative care were considered. Consensus was reached after three rounds.

Conclusions: These guidelines are based on the best available evidence for an ERAS approach to patients undergoing emergency laparotomy. Initial management is particularly important for patients with sepsis and physiological derangement. These guidelines should be used to improve outcomes for these high-risk patients.

Abstract
We evaluated the current incidence and outcome of perioperative pulmonary aspiration (PPA) in the nonobstetric adult population at a tertiary university medical center. A 4-yr retrospective analysis (January 2001-December 2004) was conducted using both quality improvement data and the hospital-wide medical archive recording system. PPA was defined as either detection of nonrespiratory secretions from the tracheobronchial tree or development of new pulmonary symptoms and/or new abnormalities in chest radiographs within 24 hr postoperatively. Of 99,441 anesthetics, 14 cases had confirmed PPA. Seven of them (50%) occurred in connection with gastroesophageal procedures. All patients had one or more predisposing risk factors for PPA. PPA occurred under general anesthesia in 10 patients and under monitored anesthesia care in 4 patients. In general anesthesia cases, the aspiration was recognized immediately after induction in 5 patients and occurred during changing of the endotracheal tubes in 5. The PPA was detected during the surgical procedures in all the monitored anesthesia care cases. Six patients with confirmed PPA developed pulmonary complications, of which, one died. Ten of 14 (70%) cases of PPA were the result of improper anesthesia technique. The current incidence of PPA is 1 of 7103, with morbidity 1 of 16,573 and mortality 1 of 99,441.

Abstract
Forty-two patients undergoing elective general surgery received either placebo, cimetidine 300 mg, or cimetidine 600 mg orally 1.5-2 h before anaesthesia in a double-blind, randomized study. Another 13 subjects received no oral premedication and served as a control group. When compared to placebo or control patients, both doses of cimetidine significantly (P less than 0.01) decreased the acidity and volume of gastric contents. None of the subjects given cimetidine were in the risk range of acid pulmonary aspiration (pH under 2.5 plus volume over 25 ml), whereas 46% of the control patients and 40% of the patients given placebo (P less than 0.005 vs cimetidine in both groups) were in the risk range.

Abstract
Purpose of review: Accurate and early identification of high-risk surgical patients allows for targeted use of perioperative monitoring and interventions that may improve their outcomes. This review summarizes current evidence on how information from the preoperative, operative, and immediate postoperative periods can help identify such individuals.

Recent findings: Simple risk indices, such as the Revised Cardiac Risk Index or American Society of Anesthesiologists Physical Status scale, and online calculators allow risk to be estimated with moderate accuracy using readily available preoperative clinical information. Both specific specialized tests (i.e., cardiopulmonary exercise testing and cardiac stress testing) and promising novel biomarkers (i.e., troponins and natriuretic peptides) can help refine these risk estimates before surgery. Estimates of perioperative risk can be further informed by information acquired during the operative and immediate postoperative periods, such as risk indices (i.e., surgical Apgar score), individual risk factors (i.e., intraoperative hypotension), or postoperative biomarkers (i.e., troponins and natriuretic peptides).

Summary: Preoperative clinical risk indices and risk calculators estimate surgical risk with moderate accuracy. Although novel biomarkers, specialized preoperative testing, and immediate postoperative risk indices show promise as methods to refine these risk estimates, more research is needed on how best to integrate risk information from these different sources.

Abstract
Background: This is Part 2 of the first consensus guidelines for optimal care of patients undergoing emergency laparotomy (EL) using an Enhanced Recovery After Surgery (ERAS) approach. This paper addresses intra- and postoperative aspects of care.

Methods: Experts in aspects of management of high-risk and emergency general surgical patients were invited to contribute by the International ERAS® Society. PubMed, Cochrane, Embase, and Medline database searches were performed for ERAS elements and relevant specific topics. Studies on each item were selected with particular attention to randomized clinical trials, systematic reviews, meta-analyses, and large cohort studies and reviewed and graded using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. Recommendations were made on the best level of evidence, or extrapolation from studies on elective patients when appropriate. A modified Delphi method was used to validate final recommendations. Some ERAS® components covered in other guideline papers are outlined only briefly, with the bulk of the text focusing on key areas pertaining specifically to EL.

Results: Twenty-three components of intraoperative and postoperative care were defined. Consensus was reached after three rounds of a modified Delphi Process.

Conclusions: These guidelines are based on best available evidence for an ERAS® approach to patients undergoing EL. These guidelines are not exhaustive but pull together evidence on important components of care for this high-risk patient population. As much of the evidence is extrapolated from elective surgery or emergency general surgery (not specifically laparotomy), many of the components need further evaluation in future studies.

Abstract
Extended bouts of fasting are ingrained in the ecology of many organisms, characterizing aspects of reproduction, development, hibernation, estivation, migration, and infrequent feeding habits. The challenge of long fasting episodes is the need to maintain physiological homeostasis while relying solely on endogenous resources. To meet that challenge, animals utilize an integrated repertoire of behavioral, physiological, and biochemical responses that reduce metabolic rates, maintain tissue structure and function, and thus enhance survival. We have synthesized in this review the integrative physiological, morphological, and biochemical responses, and their stages, that characterize natural fasting bouts. Underlying the capacity to survive extended fasts are behaviors and mechanisms that reduce metabolic expenditure and shift the dependency to lipid utilization. Hormonal regulation and immune capacity are altered by fasting; hormones that trigger digestion, elevate metabolism, and support immune performance become depressed, whereas hormones that enhance the utilization of endogenous substrates are elevated. The negative energy budget that accompanies fasting leads to the loss of body mass as fat stores are depleted and tissues undergo atrophy (i.e., loss of mass). Absolute rates of body mass loss scale allometrically among vertebrates. Tissues and organs vary in the degree of atrophy and downregulation of function, depending on the degree to which they are used during the fast. Fasting affects the population dynamics and activities of the gut microbiota, an interplay that impacts the host's fasting biology. Fasting-induced gene expression programs underlie the broad spectrum of integrated physiological mechanisms responsible for an animal's ability to survive long episodes of natural fasting.

Abstract
While intake of clear fluids 2-3 h before surgery is considered safe as it does not influence gastric content, it is not known if the same applies to a light breakfast meal. We therefore studied gastric emptying of a light breakfast in healthy, female volunteers without evidence of gastrointestinal motility disorders. The test meal consisted of one slice of buttered toast with jam, one cup of coffee without milk or sugar and one glass of pulp-free orange juice taken together with a paracetamol mixture. Using gastric ultrasonography, the stomach was identified without problems in all subjects, and gastric emptying curves using changes in gastric antral area and serum-paracetamol were obtained. Emptying of the fluid phase started immediately after intake of the meal. All subjects had solid particles in the stomach 120 min after the meal, 3 patients were considered empty after 180 min, 6 after 210 min and all after 240 min. The gastric antral area returned to fasting value significantly faster than the disappearance of solid particles; median 150 min versus 210 min; P = 0.01. Our results show that in healthy subjects the stomach cannot be considered empty for solid particles the first 4 h after a light breakfast meal. To secure some safety limits, we suggest a 6-h mandatory preoperative fast after a light breakfast.

Abstract
Background: Managing medications inappropriately when patients have oral intake restrictions can cause patient harm. This study evaluated the impact of a medication policy separating fasting from nil by mouth with respect to giving oral medications in patients fasting before a diagnostic or interventional procedure.

Methods: The policy stipulated that 'fasting' means oral medications should be given with a sip of water up to 1 hour before a procedure, unless there is a clinical reason to withhold, while 'nil by mouth' means nothing to be given orally, including medications.The policy was implemented in Surgical areas in February 2015 and Medical areas in March 2015 at a tertiary referral hospital in Melbourne, Australia, and included bedside signs, clinical champions and education sessions.The study was conducted in 2020. Admission and medication records were matched for non-elective procedure patients from January 2014 to May 2016. The monthly proportion of doses omitted inappropriately and overall omissions pre/post-policy implementation were compared using segmented regression.

Results: Pre-implementation, the proportion of doses withheld inappropriately and total omissions in medical areas were 18.1% and 28.0%, respectively. Post-implementation, an absolute reduction of 13.4% (95% CI 9.0% to 17.7%) and 11.1% (95% CI 2.6% to 19.6%), respectively, was seen. Post-implementation linear trend showed a 0.3% (95% CI 0.0% to 0.6%) increase in inappropriate omissions but not overall omissions.In Surgical areas, pre-implementation proportions for inappropriate and overall omissions were lower than Medical areas'. Post-implementation, there was an absolute decrease in doses withheld inappropriately (8.3%, 95% CI 0.8% to 15.7%, from 11.9% pre-implementation) but not total omissions.

Conclusions: Distinguishing fasting from nil by mouth appeared to provide clarity for some staff: a reduction in inappropriate omissions was seen post-implementation. Although the small increase in post-implementation linear trend for inappropriate omissions in Medical areas suggests sustainability issues, total omissions were sustained. The policy's concepts require verification beyond our institution.

Abstract
Background: Perioperative pulmonary aspiration of gastric contents has been associated with severe morbidity and death. The primary aim of this study was to identify outcomes and patient and process of care risk factors associated with gastric aspiration claims in the Anesthesia Closed Claims Project. The secondary aim was to assess these claims for appropriateness of care. The hypothesis was that these data could suggest opportunities to reduce either the risk or severity of perioperative pulmonary aspiration.

Methods: Inclusion criteria were anesthesia malpractice claims in the American Society of Anesthesiologists Closed Claims Project that were associated with surgical, procedural, or obstetric anesthesia care with the year of the aspiration event 2000 to 2014. Claims involving pulmonary aspiration were identified and assessed for patient and process factors that may have contributed to the aspiration event and outcome. The standard of care was assessed for each claim.

Results: Aspiration of gastric contents accounted for 115 of the 2,496 (5%) claims in the American Society of Anesthesiologists Closed Claims Project that met inclusion criteria. Death directly related to pulmonary aspiration occurred in 66 of the 115 (57%) aspiration claims. Another 16 of the 115 (14%) claims documented permanent severe injury. Seventy of the 115 (61%) patients who aspirated had either gastrointestinal obstruction or another acute intraabdominal process. Anesthetic management was judged to be substandard in 62 of the 115 (59%) claims.

Conclusions: Death and permanent severe injury were common outcomes of perioperative pulmonary aspiration of gastric contents in this series of closed anesthesia malpractice claims. The majority of the patients who aspirated had either gastrointestinal obstruction or acute intraabdominal processes. Anesthesia care was frequently judged to be substandard. These findings suggest that clinical practice modifications to preoperative assessment and anesthetic management of patients at risk for pulmonary aspiration may lead to improvement of their perioperative outcomes.

Abstract
Background: Pulmonary aspiration of gastric contents during the perioperative period may be associated with postoperative mortality or pulmonary morbidity. Recent determination of the incidence of perioperative pulmonary aspiration and evaluation of factors related to clinical outcomes is lacking.

Methods: We retrospectively reviewed the perioperative courses of 172,334 consecutive patients 18 yr of age or older who underwent 215,488 general anesthetics for procedures performed in all surgical specialties from July 1985 to June 1991. Pulmonary aspiration was defined as either the presence of bilious secretions or particulate matter in the tracheobronchial tree or, in patients who did not have their tracheobronchial airways directly examined after regurgitation, the presence of an infiltrate on postoperative chest roentgenogram that was not identified by preoperative roentgenogram or physical examination.

Results: Pulmonary aspiration occurred in 67 patients (1:3,216 anesthetics). Fifteen aspirations occurred in 13,427 (1:895) anesthetics of patients undergoing emergency surgery, and 52 occurred in 202,061 (1:3,886) anesthetics of patients undergoing elective surgery (P < .001). Of the 66 patients who survived their surgery, 42 (64%) did not develop a cough or wheeze, a decrease in arterial hemoglobin oxygen saturation while breathing room air > 10% less than the preoperative value, or radiographic abnormalities within 2 h of aspiration. These 42 patients had no respiratory sequelae. Of the 24 patients who had one or more of these findings, 13 required mechanical ventilatory support for more than 6 h. Three of the six patients whose lungs required mechanical ventilation for more than 24 h died from pulmonary insufficiency (overall mortality = 1:71,829 anesthetics).

Conclusions: This study suggests that patients with clinically apparent aspiration who do not develop symptoms within 2 h are unlikely to have respiratory sequelae.