Hypocapnia and hypercapnia are predictors for ICU admission and mortality in hospitalized patients with community-acquired pneumonia.
OBJECTIVE
The purpose of our study was to examine in patients hospitalized with community acquired pneumonia (CAP) the association between abnormal Pa CO 2 and ICU admission and 30-day mortality.


METHODS
A retrospective cohort study was conducted at two tertiary teaching hospitals. Eligible subjects were admitted with a diagnosis of CAP. Arterial blood gas analyses were obtained with measurement of PaCO2 on admission. Multivariate analyses were performed using 30-day mortality and ICU admission as the dependent measures.


RESULTS
Data were abstracted on 453 subjects with a documented arterial blood gas analysis. One hundred eighty-nine patients (41%) had normal PaCO2 (35-45 mm Hg), 194 patients (42%) had aPa CO 2 , 35 mm Hg (hypocapnic), and 70 patients (15%) had a Pa CO 2 . 45 mm Hg (hypercapnic).In the multivariate analysis, after adjusting for severity of illness, hypocapnic patients had greater 30-day mortality (OR= 2.84; 95% CI, 1.28-6.30) and a higher need for ICU admission (OR= 2.88;95% CI, 1.68-4.95) compared with patients with normal PaCO2. In addition, hypercapnic patients had a greater 30-day mortality (OR= 3.38; 95% CI, 1.38-8.30) and a higher need for ICU admission(OR =5.35; 95% CI, 2.80-10.23). When patients with COPD were excluded from the analysis,the differences persisted between groups.


CONCLUSIONS
In hospitalized patients with CAP, both hypocapnia and hypercapnia were associated with an increased need for ICU admission and higher 30-day mortality. These findings persisted after excluding patients with CAP and with COPD. Therefore, PaCO2 should be considered for inclusion in future severity stratification criteria to appropriate identified patients who will require a higher level of care and are at risk for increased mortality.
University of Texas Health Science Center at San Antonio, San Antonio, TX; Servei de Pneumologia, Hospital Comarcal de Mollet, Mollet del Valles, Spain.
Elena
E
Laserna
University of Texas Health Science Center at San Antonio, San Antonio, TX; Servei de Pneumologia Hospital de la Santa Creui Sant Pau, Barcelona, Spain.
Oriol
O
Sibila
University of Texas Health Science Center at San Antonio, San Antonio, TX.
Patrick R
PR
Aguilar
VA North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, TX.
Eric M
EM
Mortensen
University of Texas Health Science Center at San Antonio, San Antonio, TX; South Texas Veterans Health Care System, San Antonio, TX.
Antonio
A
Anzueto
Unidad de Cuidados Intensivos Respiratorios Hospital Clinic Universitari, Valencia, Spain.
Jose M
JM
Blanquer
Servicio de Neumologia, Consorci Hospital General Universitari, Valencia, Spain.
Francisco
F
Sanz
Servei de Medicina Intensiva, Hospital de la Vall d' Hebron, CIBERES, VHICU, Universitat Autonoma de Barcelona, Barcelona, Spain.
Jordi
J
Rello
Servicio de Neumologia Complejo Hospitalario Universitario de A Coruna, A Coruna, Spain.
Pedro J
PJ
Marcos
University of Texas Health Science Center at San Antonio, San Antonio, TX; South Texas Veterans Health Care System, San Antonio, TX.
Maria I
MI
Velez
University of Texas Health Science Center at San Antonio, San Antonio, TX.
Nivin
N
Aziz
University of Texas Health Science Center at San Antonio, San Antonio, TX; South Texas Veterans Health Care System, San Antonio, TX; Veterans Evidence Based Research Dissemination and Implementation Center (VERDICT), San Antonio, TX. Electronic address: restrepom@uthscsa.edu.
Marcos I
MI
Restrepo
D001784:Blood Gas Analysis; D017714:Community-Acquired Infections / Q000175:diagnosis* / Q000401:mortality*; D015897:Comorbidity; D003710:Demography; D005260:Female; D017052:Hospital Mortality; D006784:Hospitals, Teaching; D006801:Humans; D006935:Hypercapnia / Q000401:mortality*; D016857:Hypocapnia / Q000401:mortality*; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000175:diagnosis* / Q000401:mortality*; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015996:Survival Rate; D013781:Texas / Q000453:epidemiology