title: Weaning mechanical ventilation after off-pump coronary artery bypass graft procedures directed by noninvasive gas measurements.
abstract: OBJECTIVE
  Partial pressure of carbon dioxide and oxygen were transcutaneously measured in adults after off-pump coronary artery bypass (OPCAB) surgery. The clinical use of such measurements and interchangeability with arterial blood gas measurements for weaning patients from postoperative mechanical ventilation were assessed.
  
  
  METHODS
  This was a prospective observational study.
  
  
  METHODS
  Tertiary referral heart hospital.
  
  
  METHODS
  Postoperative OPCAB surgical patients.
  
  
  METHODS
  Transcutaneous oxygen and carbon dioxide measurements.
  
  
  RESULTS
  In this prospective observational study, 32 consecutive adult patients in a tertiary care medical center underwent OPCAB surgery. Noninvasive measurement of respiratory gases was performed during the postoperative period and compared with arterial blood gases. The investigator was blinded to the reports of arterial blood gas studies and weaned patients using a "weaning protocol" based on transcutaneous gas measurement. The number of patients successfully weaned based on transcutaneous measurements and the number of times the weaning process was held up were noted. A total of 212 samples (pairs of arterial and transcutaneous values of oxygen and carbon dioxide) were obtained from 32 patients. Bland-Altman plots and mountain plots were used to analyze the interchangeability of the data. Twenty-five (79%) of the patients were weaned from the ventilator based on transcutaneous gas measurements alone. Transcutaneous carbon dioxide measurements were found to be interchangeable with arterial carbon dioxide during 96% of measurements, versus 79% for oxygen measurements.
  
  
  CONCLUSIONS
  More than three fourths of the patients were weaned from mechanical ventilation and extubated based on transcutaneous gas values alone after OPCAB surgery. The noninvasive transcutaneous carbon dioxide measurement can be used as a surrogate for arterial carbon dioxide measurement to manage postoperative OPCAB patients.
authors.affiliation: Wockhardt Hospitals, Bangalore, India. mailchakravarthy@gmail.com
authors.forename: Murali
authors.initials: M
authors.lastname: Chakravarthy
authors.forename: Sandeep
authors.initials: S
authors.lastname: Narayan
authors.forename: Raghav
authors.initials: R
authors.lastname: Govindarajan
authors.forename: Vivek
authors.initials: V
authors.lastname: Jawali
authors.forename: Subramanyam
authors.initials: S
authors.lastname: Rajeev
mesh_terms: D000368:Aged; D001785:Blood Gas Monitoring, Transcutaneous / Q000295:instrumentation / Q000379:methods*; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D006348:Cardiac Surgical Procedures; D047549:Coronary Artery Bypass, Off-Pump; D003422:Critical Care; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011182:Postoperative Care / Q000379:methods; D011446:Prospective Studies; D015203:Reproducibility of Results; D015300:Ventilator Weaning / Q000379:methods*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen