title: Current ventilation practice during general anaesthesia: a prospective audit in Melbourne, Australia.
abstract: BACKGROUND
  Recent evidence suggests that the use of low tidal volume ventilation with the application of positive end-expiratory pressure (PEEP) may benefit patients at risk of respiratory complications during general anaesthesia. However current Australian practice in this area is unknown.
  
  
  METHODS
  To describe current practice of intraoperative ventilation with regard to tidal volume and application of PEEP, we performed a multicentre audit in patients undergoing general anaesthesia across eight teaching hospitals in Melbourne, Australia.
  
  
  RESULTS
  We obtained information including demographic characteristics, type of surgery, tidal volume and the use of PEEP in a consecutive cohort of 272 patients. The median age was 56 (IQR 42-69) years; 150 (55%) were male. Most common diagnostic groups were general surgery (31%), orthopaedic surgery (20%) and neurosurgery (9.6%). Mean FiO2 was 0.6 (IQR 0.5-0.7). Median tidal volume was 500 ml (IQR 450-550). PEEP was used in 54% of patients with a median value of 5.0 cmH2O (IQR 4.0-5.0) and median tidal volume corrected for predicted body weight was 9.5 ml/kg (IQR 8.5-10.4). Median peak inspiratory pressure was 18 cmH2O (IQR 15-22). In a cohort of patients considered at risk for respiratory complications, the median tidal volume was still 9.8 ml/kg (IQR 8.6-10.7) and PEEP was applied in 66% of patients with a median value of 5 cmH20 (IQR 4-5). On multivariate analyses positive predictors of tidal volume size included male sex (p < 0.01), height (p = 0.04) and weight (p < 0.001). Positive predictors of the use of PEEP included surgery in a tertiary hospital (OR = 3.11; 95% CI: 1.05 to 9.23) and expected prolonged duration of surgery (OR = 2.47; 95% CI: 1.04 to 5.84).
  
  
  CONCLUSIONS
  In mechanically ventilated patients under general anaesthesia, tidal volume was high and PEEP was applied to the majority of patients, but at modest levels. The findings of our study suggest that the control groups of previous randomized controlled trials do not closely reflect the practice of mechanical ventilation in Australia.
authors.affiliation: Department of Intensive Care, Austin Hospital, Melbourne, Australia ; Department of Anaesthesia, Austin Hospital, Melbourne, Australia.
authors.forename: Dharshi
authors.initials: D
authors.lastname: Karalapillai
authors.affiliation: Department of Anaesthesia, Austin Hospital, Melbourne, Australia.
authors.forename: Laurence
authors.initials: L
authors.lastname: Weinberg
authors.affiliation: Department of Anesthesia, Royal Melbourne Hospital, Melbourne, Australia.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Galtieri
authors.affiliation: Department of Intensive Care, Austin Hospital, Melbourne, Australia.
authors.forename: Neil
authors.initials: N
authors.lastname: Glassford
authors.affiliation: Department of Intensive Care, Austin Hospital, Melbourne, Australia.
authors.forename: Glenn
authors.initials: G
authors.lastname: Eastwood
authors.affiliation: Department of Anesthesia, Royal Melbourne Hospital, Melbourne, Australia.
authors.forename: Jai
authors.initials: J
authors.lastname: Darvall
authors.affiliation: Department of Anaesthesia, Northern Hospital, Melbourne, Australia.
authors.forename: Jake
authors.initials: J
authors.lastname: Geertsema
authors.affiliation: Department of Anaesthesia, Box Hill Hospital, Melbourne, Australia.
authors.forename: Ravi
authors.initials: R
authors.lastname: Bangia
authors.affiliation: Department of Anaesthesia, Alfred Hospital, Melbourne, Australia.
authors.forename: Jane
authors.initials: J
authors.lastname: Fitzgerald
authors.affiliation: Department of Anaesthesia, St Vincents Hospital, Melbourne, Australia.
authors.forename: Tuong
authors.initials: T
authors.lastname: Phan
authors.affiliation: Department of Anaesthesia, Monash Medical Centre, Melbourne, Australia.
authors.forename: Luke
authors.initials: L
authors.lastname: OHallaran
authors.affiliation: Department of Anaesthesia, Western Health, Melbourne, Australia.
authors.forename: Adriano
authors.initials: A
authors.lastname: Cocciante
authors.affiliation: Department of Anaesthesia, Western Health, Melbourne, Australia.
authors.forename: Stuart
authors.initials: S
authors.lastname: Watson
authors.affiliation: University of Melbourne, Melbourne, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Story
authors.affiliation: Intensive Care Research, Austin Hospital and Co-director, Australian and New Zealand Intensive Care Research Centre (ANZIC-RC), Melbourne, Australia ; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Bellomo
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General / Q000379:methods*; D001315:Australia; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008485:Medical Audit; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000592:standards* / Q000639:trends*; D056152:Respiratory Rate; D013990:Tidal Volume
keywords: Anaesthesia; Intraoperative ventilation; PEEP; Tidal volume