Infection/Inflammation| Volume 170, ISSUE 5, P1432-1441, November 2021

Risk factors and outcomes of postoperative aspiration pneumonia in abdominal surgery patients: An exact matching and weighting analysis



      Postoperative aspiration pneumonia is a feared complication contributing significantly to postoperative morbidity and mortality. Over decades, there has been little progress in reducing incidence and mortality of postoperative aspiration pneumonia. Here, we assessed risk factors for postoperative aspiration pneumonia in general and abdominal surgery patients.


      Patients undergoing surgery between January 2012 and December 2018 were included in this exact matched and weighted case-control study. Data from a prospectively acquired clinical database were retrospectively analyzed.


      Among 23,647 patients undergoing 32,901 operations, 144 (0.44%, 95% Confidence Interval: 0.37%–0.52%) cases of postoperative aspiration pneumonia were identified. Ninety-day mortality was 27.8% (n = 40). Major risk factors for postoperative aspiration pneumonia were emergency surgery in patients with prolonged preoperative fasting (>6 hours; odds ratio: 3.25, 95% confidence interval: 1.46–7.26; P < .001), older age with increasing risk in octogenarians compared to seniors (65–80 years: n = 69; odds ratio 5.23, 95% confidence interval: 2.18–12.51; >80 years: n = 50; odds ratio 13.72, 95% confidence interval: 4.94–38.09; P < .001), American Society of Anesthesiologists scores >II (American Society of Anesthesiologists III: n = 90; odds ratio 3.38, 95% confidence interval: 1.08–16.01; American Society of Anesthesiologists IV/V: n = 18; odds ratio 5.20, 95% confidence interval: 1.48–27.61; P < .001), and body mass index <18 kg/m2 (n = 9; odds ratio: 2.53; 95% confidence interval: 1.04–6.11; P = .029). Laparoscopies (odds ratio 0.45, 95% confidence interval: 0.23–0.88; <0.001) and female sex were associated with a decreased risk for postoperative aspiration pneumonia (odds ratio 0.40, 95% confidence interval: 0.23–0.69; P < .001).


      Preventive measures to reduce postoperative aspiration pneumonia should focus on older patients with American Society of Anesthesiologists scores ≥III undergoing open surgery. Cachectic patients and patients undergoing emergency surgery with prolonged preoperative fasting require increased attention. Laparoscopy was associated with a lower risk for postoperative aspiration pneumonia and should be preferred whenever appropriate.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Surgery
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Smetana G.W.
        • Lawrence V.A.
        • Cornell J.E.
        • American College of Physicians
        Preoperative pulmonary risk stratification for noncardiothoracic surgery: systematic review for the American College of Physicians.
        Ann Intern Med. 2006; 144: 581-595
        • Canet J.
        • Gallart L.
        • Gomar C.
        • et al.
        Prediction of postoperative pulmonary complications in a population-based surgical cohort.
        Anesthesiology. 2010; 113: 1338-1350
        • Studer P.
        • Räber G.
        • Ott D.
        • Candinas D.
        • Schnüriger B.
        Risk factors for fatal outcome in surgical patients with postoperative aspiration pneumonia.
        Int J Surg. 2016; 27: 21-25
        • Kozlow J.H.
        • Berenholtz S.M.
        • Garrett E.
        • Dorman T.
        • Pronovost P.J.
        Epidemiology and impact of aspiration pneumonia in patients undergoing surgery in Maryland, 1999-2000.
        Crit Care Med. 2003; 31: 1930-1937
        • Dimick J.B.
        • Chen S.L.
        • Taheri P.A.
        • Henderson W.G.
        • Khuri S.F.
        • Campbell D.A.
        Hospital costs associated with surgical complications: a report from the private-sector National Surgical Quality Improvement Program.
        J Am Coll Surg. 2004; 199: 531-537
        • Shander A.
        • Fleisher L.A.
        • Barie P.S.
        • Bigatello L.M.
        • Sladen R.N.
        • Watson C.B.
        Clinical and economic burden of postoperative pulmonary complications: patient safety summit on definition, risk-reducing interventions, and preventive strategies.
        Crit Care Med. 2011; 39: 2163-2172
        • Brooks-Brunn J.A.
        Risk factors associated with postoperative pulmonary complications following total abdominal hysterectomy.
        Clin Nurs Res. 2000; 9: 27-46
        • Arozullah A.M.
        • Khuri S.F.
        • Henderson W.G.
        • Daley J.
        Participants in the National Veterans Affairs Surgical Quality Improvement Program. Development and validation of a multifactorial risk index for predicting postoperative pneumonia after major noncardiac surgery.
        Ann Intern Med. 2001; 135: 847-857
        • American Society of Anesthesiologists, ed
        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: An Updated Report by the American Society of Anesthesiologists Task Force on Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration.
        Anesthesiology. 2017; 126: 376-393
        • Warner M.A.
        • Warner M.E.
        • Weber J.G.
        Clinical significance of pulmonary aspiration during the perioperative period.
        Anesthesiology. 1993; 78: 56-62
        • Katsura M.
        • Kuriyama A.
        • Takeshima T.
        • Fukuhara S.
        • Furukawa T.A.
        Preoperative inspiratory muscle training for postoperative pulmonary complications in adults undergoing cardiac and major abdominal surgery.
        Cochrane Database Syst Rev. 2015; 10CD010356
        • Nelson R.
        • Edwards S.
        • Tse B.
        Prophylactic nasogastric decompression after abdominal surgery.
        Cochrane Database Syst Rev. 2007; 2007CD0044929
        • Office FS
        Schweizerische operationsklassifikation CHOP 2019 - Systematisches Verzeichnis, Federal Statistical Office; 2018.
        (Available at:)
        • Firth D.
        Bias reduction of maximum likelihood estimates.
        Biometrika. 1993; 80: 27-38
        • Heinze G.
        • Schemper M.
        A solution to the problem of separation in logistic regression.
        Stat Med. 2002; 21: 2409-2419
        • Tang F.
        • Ishwaran H.
        Random forest missing data algorithms.
        Stat Anal Data Min. 2017; 10: 363
        • Eilers P.H.C.
        • Marx B.D.
        Flexible Smoothing with B-splines and Penalties.
        Stat Sci. 1996; 11: 89-102
        • Rosenbaum P.R.
        Model-Based Direct Adjustment.
        J Am Stat Assoc. 1987; 82: 387-394
        • Hansen B.B.
        • Klopfer S.O.
        Optimal full matching and related designs via network flows.
        J Comput Graph Stat. 2006; 15: 609-627
        • Nobili C.
        • Marzano E.
        • Oussoultzoglou E.
        • et al.
        Multivariate analysis of risk factors for pulmonary complications after hepatic resection.
        Ann Surg. 2012; 255: 540-550
        • Ohashi Y.
        • Walker J.C.
        • Zhang F.
        • et al.
        Preoperative gastric residual volumes in fasted patients measured by bedside ultrasound: a prospective observational study.
        Anaesth Intensive Care. 2018; 46: 608-613
        • Lambert E.
        • Carey S.
        Practice Guideline Recommendations on Perioperative Fasting.
        J Parenter Enter Nutr. 2016; 40: 1158-1165
        • Tsang E.
        • Lambert E.
        • Carey S.
        Fasting leads to fasting: examining the relationships between perioperative fasting times and fasting for symptoms in patients undergoing elective abdominal surgery.
        Asia Pac J Clin Nutr. 2018; 27: 968-974
        • Nguyen N.Q.
        • Ng M.P.
        • Chapman M.
        • Fraser R.J.
        • Holloway R.H.
        The impact of admission diagnosis on gastric emptying in critically ill patients.
        Crit Care. 2007; 11: R16
        • Hsu C.-W.
        • Sun S.-F.
        • Lee D.L.
        • et al.
        Impact of disease severity on gastric residual volume in critical patients.
        World J Gastroenterol. 2011; 17: 2007-2012
        • Mendelson C.L.
        The aspiration of stomach contents into the lungs during obstetric anesthesia.
        Am J Obstet Gynecol. 1946; 52: 191-205
        • Cook T.M.
        • Woodall N.
        • Frerk C.
        Fourth National Audit Project. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia.
        Br J Anaesth. 2011; 106: 617-631
        • Guimarães M.M.
        • Dib R.E.
        • Smith A.F.
        • Matos D.
        Incentive spirometry for prevention of postoperative pulmonary complications in upper abdominal surgery.
        Cochrane Database Syst Rev. 2009; 3CD006058
        • Barberan-Garcia A.
        • Ubré M.
        • Roca J.
        • et al.
        Personalised prehabilitation in high-risk patients undergoing elective major abdominal surgery: a randomized blinded controlled trial.
        Ann Surg. 2018; 267: 50-56
        • Smetana G.W.
        Preoperative pulmonary evaluation.
        N Engl J Med. 1999; 340: 937-944
        • Yang C.K.
        • Teng A.
        • Lee D.Y.
        • Rose K.
        Pulmonary complications after major abdominal surgery: National Surgical Quality Improvement Program analysis.
        J Surg Res. 2015; 198: 441-449
        • Blouw E.L.
        • Rudolph A.D.
        • Narr B.J.
        • Sarr M.G.
        The frequency of respiratory failure in patients with morbid obesity undergoing gastric bypass.
        AANA J. 2003; 71: 45-50
        • Mullen J.T.
        • Davenport D.L.
        • Hutter M.M.
        • et al.
        Impact of body mass index on perioperative outcomes in patients undergoing major intra-abdominal cancer surgery.
        Ann Surg Oncol. 2008; 15: 2164-2172
        • Pedersen T.
        • Viby-Mogensen J.
        • Ringsted C.
        Anaesthetic practice and postoperative pulmonary complications.
        Acta Anaesthesiol Scand. 1992; 36: 812-818
        • Pereira E.D.
        • Fernandes A.L.
        • da Silva Anção M.
        • de Araúja Pereres C.
        • Atallah A.N.
        • Faresin S.M.
        Prospective assessment of the risk of postoperative pulmonary complications in patients submitted to upper abdominal surgery.
        Sao Paulo Med J Rev Paul Med. 1999; 117: 151-160
        • McAlister F.A.
        • Bertsch K.
        • Man J.
        • Bradley J.
        • Jacka M.
        Incidence of and risk factors for pulmonary complications after nonthoracic surgery.
        Am J Respir Crit Care Med. 2005; 171: 514-517
        • Lawrence V.A.
        • Cornell J.E.
        • Smetana G.W.
        • American College of Physicians
        Strategies to reduce postoperative pulmonary complications after noncardiothoracic surgery: systematic review for the American College of Physicians.
        Ann Intern Med. 2006; 144: 596-608
        • Thomsen T.
        • Villebro N.
        • Møller A.M.
        Interventions for preoperative smoking cessation.
        Cochrane Database Syst Rev. 2014; 2014CD002294
        • Lawrence V.A.
        • Hilsenbeck S.G.
        • Mulrow C.D.
        • Dhanda R.
        • Sapp J.
        • Page C.P.
        Incidence and hospital stay for cardiac and pulmonary complications after abdominal surgery.
        J Gen Intern Med. 1995; 10: 671-678
        • Arozullah A.M.
        • Daley J.
        • Henderson W.G.
        • Khuri S.F.
        Multifactorial risk index for predicting postoperative respiratory failure in men after major noncardiac surgery.
        Ann Surg. 2000; 232: 242-253
        • Soutome S.
        • Yanamoto S.
        • Funahara M.
        • et al.
        Effect of perioperative oral care on prevention of postoperative pneumonia associated with esophageal cancer surgery: A multicenter case–control study with propensity score matching analysis.
        Medicine (Baltimore). 2017; 96e7436
        • Mitchell C.K.
        • Smoger S.H.
        • Pfeifer M.P.
        • et al.
        Multivariate analysis of factors associated with postoperative pulmonary complications following general elective surgery.
        Arch Surg. 1998; 133: 194-198
        • Lawrence V.A.
        • Dhanda R.
        • Hilsenbeck S.G.
        • Page C.P.
        Risk of pulmonary complications after elective abdominal surgery.
        Chest. 1996; 110: 744-750
        • Abbott T.E.F.
        • Fowler A.J.
        • Pelosi P.
        • et al.
        A systematic review and consensus definitions for standardised end-points in perioperative medicine: pulmonary complications.
        Br J Anaesth. 2018; 120: 1066-1079
        • Lindenauer P.K.
        • Strait K.M.
        • Grady J.N.
        • et al.
        Variation in the diagnosis of aspiration pneumonia and association with hospital pneumonia outcomes.
        Ann Am Thorac Soc. 2018; 15: 562-569