title: Energy metabolism of thoracic surgical patients in the early postoperative period. Effect of posture.
abstract: OBJECTIVE
  To determine the effect of elective thoracic surgery on energy metabolism and gas exchange and to evaluate whether the 30-degree sitting position would affect these variables.
  
  
  METHODS
  Prospective, unblinded, controlled study.
  
  
  METHODS
  Surgical ICU in a university hospital.
  
  
  METHODS
  Twenty-two adult patients undergoing elective pulmonary resection.
  
  
  METHODS
  Posture change from supine to 30-degree sitting position.
  
  
  RESULTS
  Oxygen consumption (VO2), carbon dioxide production (VCO2), respiratory quotient (RQ), and energy expenditure (EE) were measured by means of computerized indirect calorimetry before and after surgery. Heart rate and respiratory frequency were measured continuously during gas exchange measurement. Blood gases were analyzed with an automated blood gas analyzer. Preoperatively, altering position did not affect energy metabolism, gas exchange, and cardiopulmonary variables. Postoperatively, the measured EE was 116% of the expected value. Mean EE and VO2 values for each position were higher than the preoperative values for the corresponding postures (p<0.05 for each position), while VCO2 increased only in the supine position (p<0.05). Mean percent increases in EE, VO2, and VCO2 were significantly lower in the 30-degree sitting position than in the supine position (EE: 7.9+/-2.7% vs 14.4+/-2.3%; p<0.001; VO2: 9.0+/-3.0% vs 16.4+/- 2.6%; p<0.001; VCO2: 3.2+/-2.1% vs 6.5+/-1.4%: p<0.05). Arterial oxygen tension and all the physiologic indexes of gas exchange for each position were worse than the preoperative values for the corresponding postures (p<0.05 for each position). Mean arterial pressure, heart rate, and respiratory frequency for each position were higher than the preoperative values for the corresponding postures (p<0.05 for each position). No changes in mean values of these variables occurred between the two positions postoperatively.
  
  
  CONCLUSIONS
  The early postoperative period of patients undergoing elective thoracic surgery is characterized by a condition of impaired gas exchange and by a hypermetabolic state. Hypermetabolism can be partly mitigated by assuming the 30-degree sitting position.
authors.affiliation: Department of Surgery, Intensive Care Unit at School of Anesthesiology and Intensive Care, University of Pisa, Italy.
authors.forename: L S
authors.initials: LS
authors.lastname: Brandi
authors.forename: R
authors.initials: R
authors.lastname: Bertolini
authors.forename: A
authors.initials: A
authors.lastname: Janni
authors.forename: A
authors.initials: A
authors.lastname: Gioia
authors.forename: C A
authors.initials: CA
authors.lastname: Angeletti
mesh_terms: D000368:Aged; D017558:Elective Surgical Procedures; D004734:Energy Metabolism; D006439:Hemodynamics; D006801:Humans; D008175:Lung Neoplasms / Q000503:physiopathology / Q000601:surgery; D008875:Middle Aged; D010101:Oxygen Consumption; D011013:Pneumonectomy; D011182:Postoperative Care; D011184:Postoperative Period; D011187:Posture; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange