Document Detail

Supplemental oxygen impairs detection of hypoventilation by pulse oximetry.
MedLine Citation:
PMID:  15539726     Owner:  NLM     Status:  MEDLINE    
STUDY OBJECTIVE: This two-part study was designed to determine the effect of supplemental oxygen on the detection of hypoventilation, evidenced by a decline in oxygen saturation (Spo(2)) with pulse oximetry. DESIGN: Phase 1 was a prospective, patient-controlled, clinical trial. Phase 2 was a prospective, randomized, clinical trial. SETTING: Phase 1 took place in the operating room. Phase 2 took place in the postanesthesia care unit (PACU). PATIENTS: In phase 1, 45 patients underwent abdominal, gynecologic, urologic, and lower-extremity vascular operations. In phase 2, 288 patients were recovering from anesthesia. INTERVENTIONS: In phase 1, modeling of deliberate hypoventilation entailed decreasing by 50% the minute ventilation of patients receiving general anesthesia. Patients breathing a fraction of inspired oxygen (Fio(2)) of 0.21 (n = 25) underwent hypoventilation for up to 5 min. Patients with an Fio(2) of 0.25 (n = 10) or 0.30 (n = 10) underwent hypoventilation for 10 min. In phase 2, spontaneously breathing patients were randomized to breathe room air (n = 155) or to receive supplemental oxygen (n = 133) on arrival in the PACU. MEASUREMENTS AND RESULTS: In phase 1, end-tidal carbon dioxide and Spo(2) were measured during deliberate hypoventilation. A decrease in Spo(2) occurred only in patients who breathed room air. No decline occurred in patients with Fio(2) levels of 0.25 and 0.30. In phase 2, Spo(2) was recorded every min for up to 40 min in the PACU. Arterial desaturation (Spo(2) < 90%) was fourfold higher in patients who breathed room air than in patients who breathed supplemental oxygen (9.0% vs 2.3%, p = 0.02). CONCLUSION: Hypoventilation can be detected reliably by pulse oximetry only when patients breathe room air. In patients with spontaneous ventilation, supplemental oxygen often masked the ability to detect abnormalities in respiratory function in the PACU. Without the need for capnography and arterial blood gas analysis, pulse oximetry is a useful tool to assess ventilatory abnormalities, but only in the absence of supplemental inspired oxygen.
Eugene S Fu; John B Downs; John W Schweiger; Rafael V Miguel; Robert A Smith
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Publication Detail:
Type:  Clinical Trial; Clinical Trial, Phase I; Clinical Trial, Phase II; Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  Chest     Volume:  126     ISSN:  0012-3692     ISO Abbreviation:  Chest     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-11-12     Completed Date:  2005-02-03     Revised Date:  2006-01-17    
Medline Journal Info:
Nlm Unique ID:  0231335     Medline TA:  Chest     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1552-8     Citation Subset:  AIM; IM    
H. Lee Moffitt Cancer Center, 12902 Magnolia Dr, Suite 2194 Anesthesia, Tampa, FL 33612, USA.
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MeSH Terms
Hypoventilation / blood*,  diagnosis*,  therapy
Middle Aged
Oxygen Inhalation Therapy
Prospective Studies
Comment In:
Chest. 2005 Dec;128(6):4049   [PMID:  16354881 ]
Chest. 2004 Nov;126(5):1399-401   [PMID:  15539700 ]

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