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Arterial carbon dioxide tension on admission as a marker of in-hospital mortality in community-acquired pneumonia

  • Don D. Sin
    Correspondence
    Requests for reprints should be addressed to Don D. Sin, MD, MPH, James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research, St. Paul’s Hospital, Room 368A, 1081 Burrard Street, Vancouver, British Columbia V6Z 1Y6, Canada.
    Affiliations
    James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research

    Department of Medicine (Pulmonary Division), University of British Columbia, Vancouver, Canada
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  • S.F. Paul Man
    Affiliations
    James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research

    Department of Medicine (Pulmonary Division), University of British Columbia, Vancouver, Canada
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  • Thomas J. Marrie
    Affiliations
    Department of Medicine (Infectious Diseases), University of Alberta, Edmonton, Canada.
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      Purpose

      Respiratory failure is the leading cause of death among patients admitted with community-acquired pneumonia. We sought to determine the association between arterial carbon dioxide tension (PaCO2) and in-hospital mortality in patients admitted with pneumonia.

      Methods

      We analyzed data from 2171 patients aged ≥17 years who had been admitted for community-acquired pneumonia to an acute care hospital in Edmonton, Alberta. We compared the risk of all-cause in-hospital mortality using a Cox proportional hazards model across categories of PaCO2.

      Results

      Overall, in-hospital mortality was 10% (n = 218). Compared with patients with normal PaCO2 values (40 to 44 mm Hg), in-hospital mortality was greater (adjusted odds ratio [OR] = 1.8; 95% confidence interval [CI]: 1.0 to 3.2) among patients with hypocapnia (PaCO2 <32 mm Hg). In-hospital mortality was also greater (OR = 2.6; 95% CI: 1.5 to 4.5) in patients with hypercapnia (≥45 mm Hg). In-hospital mortality was similar in patients with PaCO2 values between 32 and 35 mm Hg (OR = 1.55; 95% CI: 0.89 to 2.79) and those with values between 36 and 39 mm Hg (OR = 1.42; 95% CI: 0.77 to 2.61).

      Conclusion

      Among patients admitted with community-acquired pneumonia, in-hospital mortality was greater in those with hypocapnia or hypercapnia. These data suggest that measurement of PaCO2 adds prognostic information to standard prediction rules and should be used for clinical and epidemiologic purposes to risk-stratify in-hospital patients with community-acquired pneumonia.

      Keywords

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      References

      1. Clinical Classifications for Health Policy Research. Agency for Health Care Policy and Research, Rockville, Maryland1999 (AHCPR Publication No. 99-0034)
        • Hoyert D.L.
        • Anderson R.N.
        Age-adjusted death rates.
        Natl Vital Stat Rep. 2001; 49: 1-6
        • Fine M.J.
        • Smith M.A.
        • Carson C.A.
        • et al.
        Prognosis and outcomes of patients with community-acquired pneumonia. A meta-analysis.
        JAMA. 1996; 275: 134-141
        • Fine M.J.
        • Singer D.E.
        • Phelps A.L.
        • et al.
        Differences in length of hospital stay in patients with community-acquired pneumonia.
        Med Care. 1993; 31: 371-380
        • Iezzoni L.I.
        The risks of risk adjustment.
        JAMA. 1997; 278: 1600-1607
        • Rosenthal G.E.
        • Harper D.L.
        • Quinn L.M.
        • Cooper G.S.
        Severity-adjusted mortality and length of stay in teaching and nonteaching hospitals. Results of a regional study.
        JAMA. 1997; 278: 485-490
        • Fine M.J.
        • Auble T.E.
        • Yealy D.M.
        • et al.
        A prediction rule to identify low-risk patients with community-acquired pneumonia.
        N Engl J Med. 1997; 336: 243-250
        • Conte H.A.
        • Chen Y.T.
        • Mehal W.
        • et al.
        A prognostic rule for elderly patients admitted with community-acquired pneumonia.
        Am J Med. 1999; 106: 20-28
        • Lim W.S.
        • Lewis S.
        • Macfarlane J.T.
        Severity prediction rules in community acquired pneumonia.
        Thorax. 2000; 55: 219-223
        • Ewig S.
        • Kleinfeld T.
        • Bauer T.
        • et al.
        Comparative validation of prognostic rules for community-acquired pneumonia in an elderly population.
        Eur Respir J. 1999; 14: 370-375
        • Caruana-Montaldo B.
        • Gleeson K.
        • Zwillich C.W.
        The control of breathing in clinical practice.
        Chest. 2000; 117: 205-225
        • Malcolm C.
        • Marrie T.J.
        Antibiotic therapy for ambulatory patients with community-acquired pneumonia in an emergency department setting.
        Arch Intern Med. 2003; 163: 797-802
        • Blair E.
        Hypocapnia and gram negative bacteremic shock.
        Am J Surg. 1970; 119: 433-439
        • Laffey J.G.
        • Kavanagh B.P.
        Hypocapnia.
        N Engl J Med. 2002; 347: 43-53
        • Trimble C.
        • Smith D.E.
        • Rosenthal M.H.
        • Fosburg R.G.
        Pathophysiologic role of hypocarbia in post-traumatic pulmonary insufficiency.
        Am J Surg. 1971; 122: 633-638
        • Bigatello L.M.
        • Patroniti N.
        • Sangalli F.
        Permissive hypercapnia.
        Curr Opin Crit Care. 2001; 7: 34-40
        • Feihl F.
        • Eckert P.
        • Brimioulle S.
        • Jacobs O.
        • et al.
        Permissive hypercapnia impairs pulmonary gas exchange in the acute respiratory distress syndrome.
        Am J Respir Crit Care Med. 2000; 162: 209-215
        • Smith G.L.
        • Austin C.
        • Crichton C.
        • Wray S.
        A review of the actions and control of intracellular pH in vascular smooth muscle.
        Cardiovasc Res. 1998; 38: 316-331
        • Ingram Jr, R.H.
        Effects of airway versus arterial CO2 changes on lung mechanics in dogs.
        J Appl Physiol. 1975; 38: 603-607
        • Orchard C.H.
        • Kentish J.C.
        Effects of changes of pH on the contractile function of cardiac muscle.
        Am J Physiol. 1990; 258: C967-C981
        • Horowitz L.N.
        • Spear J.F.
        • Moore E.N.
        • Rogers R.
        Effects of aminophylline on the threshold for initiating ventricular fibrillation during respiratory failure.
        Am J Cardiol. 1975; 35: 376-379
        • Max B.
        This and that.
        Trends Pharmacol Sci. 1991; 12: 408-411
        • Mortensen E.M.
        • Coley C.M.
        • Singer D.E.
        • et al.
        Causes of death for patients with community-acquired pneumonia.
        Arch Intern Med. 2002; 162: 1059-1064