title: Deep Breathing Improves End-Tidal Carbon Dioxide Monitoring of an Oxygen Nasal Cannula-Based Capnometry Device in Subjects Extubated After Abdominal Surgery.
abstract: BACKGROUND
  Capnometry detects hypoventilation earlier than pulse oximetry while supplemental oxygen is being administered. We compared the end-tidal CO2(PETCO2) measured using a newly developed oxygen nasal cannula with a CO2-sampling port and the PaCO2in extubated subjects after abdominal surgery. We also investigated whether the difference between PaCO2and PETCO2is affected by resting, by spontaneous breathing with the mouth consciously closed, and by deep breathing with the mouth closed.
  
  
  METHODS
  Adult post-abdominal surgery subjects admitted to the ICU were enrolled. After extubation, oxygen was supplied at 4 L/min using a capnometry-type oxygen cannula. The breathing frequency, PETCO2, and PaCO2were measured after 30 min of oxygen supplementation. PETCO2was continuously measured during rest, during breathing with the mouth consciously closed, and during deep breathing with the mouth closed. The difference between PETCO2and PaCO2during various breathing patterns was analyzed using the Bland-Altman method.
  
  
  RESULTS
  Twenty subjects were included. The bias ± SD (limits of agreement) for breathing frequency measured by capnometry compared with those obtained by direct measurement was 0.4 ± 3.6 (-6.7 to 7.4). In PETCO2compared with PaCO2, the biases (limits of agreement) were 14.8 ± 8.2 (-1.3 to 30.9) at rest, 10.2 ± 6.4 (-2.3 to 22.7) with the mouth closed, and 7.7 ± 5.6 (-3.2 to 18.6) for deep breathing with the mouth closed. PETCO2determined using the capnometry device yielded unreliable and widely ranging values under various breathing patterns. However, deep breathing with the mouth closed decreased the difference between PETCO2and PaCO2, as compared with other breathing patterns.
  
  
  CONCLUSIONS
  PETCO2measurements under deep breathing with mouth closed with a capnometry-type oxygen cannula improved the prediction of the absolute value of PaCO2in extubated post-abdominal surgical subjects without respiratory dysfunction.
authors.affiliation: Intensive Care Unit shunty5323@gmail.com.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Takaki
authors.affiliation: Intensive Care Unit.
authors.forename: Kenji
authors.initials: K
authors.lastname: Mizutani
authors.affiliation: Intensive Care Unit.
authors.forename: Moeka
authors.initials: M
authors.lastname: Fukuchi
authors.affiliation: Intensive Care Unit.
authors.forename: Tasuku
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: Intensive Care Unit.
authors.forename: Masahumi
authors.initials: M
authors.lastname: Idei
authors.affiliation: Intensive Care Unit.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Matsuda
authors.affiliation: Intensive Care Unit.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Intensive Care Unit.|Department of Anesthesiology, Yokohama City University, Yokohama, Kanagawa, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Miyashita
authors.affiliation: Intensive Care Unit.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nomura
authors.affiliation: Intensive Care Unit.
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamaguchi
authors.affiliation: Intensive Care Unit.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Goto
mesh_terms: D000005:Abdomen / Q000601:surgery; D000368:Aged; D060666:Airway Extubation; D001784:Blood Gas Analysis; D001944:Breath Tests; D000072601:Cannula; D002245:Carbon Dioxide / Q000032:analysis* / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D010100:Oxygen / Q000008:administration & dosage; D010102:Oxygen Inhalation Therapy / Q000295:instrumentation; D010313:Partial Pressure; D011182:Postoperative Care / Q000295:instrumentation*; D011184:Postoperative Period; D012119:Respiration; D012143:Respiratory Physiological Phenomena; D056152:Respiratory Rate; D012146:Rest / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: PaCO2; breathing frequency; capnometry; end-tidal carbon dioxide; monitoring