Introduction: The clinical course of patients with
acute exacerbations of underlying COPD presenting with hypercapnic
respiratory failure was reviewed.
Methods: This was a
retrospective review of 138 episodes of hypercapnic respiratory failure
(Paco2 ≥ 50 mm Hg and pH ≤ 7.35). Patients
were admitted to the West Los Angeles VAMC Medical Intensive Care Unit
between 1990 and 1994.
Results: Of the 138 hypercapnic
episodes, 74 (54%) required intubation. Comparison was made with the
64 cases in which patients responded to medical therapy. Patients
requiring intubation had a greater severity of illness, with a higher
APACHE II (Acute Physiology and Chronic Health Evaluation II) score
(18 ± 5 vs 16 ± 4; p < 0.01), higher WBC, higher serum BUN,
and greater acidosis (pH, 7.26 ± 0.07 vs 7.28 ± 0.06;
p = 0.08). Those with the most severe acidosis (pH < 7.20) had the
highest intubation rate (70%) and shortest time to intubation
(2 ± 2 h), and they required the longest period of time to respond
to medical therapy (69 ± 60 h). With an initial pH of < 7.25,
there was a consistently higher intubation rate. Conversely, those with
an initial pH of 7.31 to 7.35 were less likely to be intubated (45%),
had a longer time to intubation (13 ± 18 h), and had a more rapid
response to medical therapy (30 ± 18 h). Of those patients requiring
intubation, most (78%) were intubated within 8 h of presentation,
and the vast majority (93%) by 24 h. Of those patients responding
to medical therapy, half (52%) recovered within 24 h and the vast
majority (92%) recovered within 72 h.
Conclusions: This study provides a better characterization
of the response to therapy of COPD patients with hypercapnic
respiratory failure. This should be useful in limiting or omitting
medical therapy in high-risk patients, thereby avoiding delays in
intubation as well as providing a framework for continued therapy in
those more likely to improve.