title: Effect of body mass index in acute respiratory distress syndrome.
abstract: BACKGROUND
  Obesity is associated in healthy subjects with a great reduction in functional residual capacity and with a stiffening of lung and chest wall elastance, which promote alveolar collapse and hypoxaemia. Likewise, obese patients with acute respiratory distress syndrome (ARDS) could present greater derangements of respiratory mechanics than patients of normal weight.
  
  
  METHODS
  One hundred and one ARDS patients were enrolled. Partitioned respiratory mechanics and gas exchange were measured at 5 and 15 cm H2O of PEEP with a tidal volume of 6-8 ml kg(-1) of predicted body weight. At 5 and 45 cm H2O of PEEP, two lung computed tomography scans were performed.
  
  
  RESULTS
  Patients were divided as follows according to BMI: normal weight (BMI≤25 kg m(-2)), overweight (BMI between 25 and 30 kg m(-2)), and obese (BMI>30 kg m(-2)). Obese, overweight, and normal-weight groups presented a similar lung elastance (median [interquartile range], respectively: 17.7 [14.2-24.8], 20.9 [16.1-30.2], and 20.5 [15.2-23.6] cm H2O litre(-1) at 5 cm H2O of PEEP and 19.3 [15.5-26.3], 21.1 [17.4-29.2], and 17.1 [13.4-20.4] cm H2O litre(-1) at 15 cm H2O of PEEP) and chest elastance (respectively: 4.9 [3.1-8.8], 5.9 [3.8-8.7], and 7.8 [3.9-9.8] cm H2O litre(-1) at 5 cm H2O of PEEP and 6.5 [4.5-9.6], 6.6 [4.2-9.2], and 4.9 [2.4-7.6] cm H2O litre(-1) at 15 cm H2O of PEEP). Lung recruitability was not affected by the body weight (15.6 [6.3-23.4], 15.7 [9.8-22.2], and 11.3 [6.2-15.6]% for normal-weight, overweight, and obese groups, respectively). Lung gas volume was significantly lower whereas total superimposed pressure was significantly higher in the obese compared with the normal-weight group (1148 [680-1815] vs 827 [686-1213] ml and 17.4 [15.8-19.3] vs 19.3 [18.6-21.7] cm H2O, respectively).
  
  
  CONCLUSIONS
  Obese ARDS patients do not present higher chest wall elastance and lung recruitability.
authors.affiliation: Dipartimento di Anestesia, Rianimazione (Intensiva e Subintensiva) e Terapia del Dolore, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milano, Italy Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Italy chiumello@libero.it.
authors.forename: D
authors.initials: D
authors.lastname: Chiumello
authors.affiliation: Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Colombo
authors.affiliation: Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Algieri
authors.affiliation: Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Mietto
authors.affiliation: Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Carlesso
authors.affiliation: Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Crimella
authors.affiliation: Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cressoni
authors.affiliation: Department of Anesthesiology, Emergency and Intensive Care Medicine, Georg-August University of Göttingen, Göttingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Quintel
authors.affiliation: Dipartimento di Anestesia, Rianimazione (Intensiva e Subintensiva) e Terapia del Dolore, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, Milano, Italy Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milano, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Gattinoni
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000503:physiopathology*; D012128:Respiratory Distress Syndrome / Q000150:complications* / Q000503:physiopathology*; D012129:Respiratory Function Tests / Q000706:statistics & numerical data; D014057:Tomography, X-Ray Computed
keywords: chest wall elastance; intra-abdominal pressure; lung elastance; lung gas volume; obesity; respiratory distress syndrome, adult