References: MacKinnon et al, 1991
MacKinnon DF, Craighead B, Hoehn-Saric R
Carbon dioxide provocation of anxiety and respiratory response in bipolar
J Affect Disord 2007 Apr; 99(1-3): p.45-49.
Department of Psychiatry and Behavioral Sciences, Johns Hopkins University,
Baltimore, MD, USA
BACKGROUND: Frequent bipolar/panic comorbidity implies bipolar individuals
may experience CO2-provoked anxiety and changes in respiratory patterns similar
to those experienced by individuals with panic disorder. METHODS: 16 euthymic
bipolar individuals breathed air and air combined with 5% CO2 for 15 min each.
Respiratory and subjective anxiety measures were collected. RESULTS: On CO2
subjects were more anxious and breathed more deeply and rapidly than with air;
the degree of increase in anxiety attributable to CO2 was directly correlated
with the degree of increase in minute ventilation. Five individuals were
assessed as having a panic attack. Panic response to CO2 was predicted by the
degree of anxiety experienced with air alone. CONCLUSIONS: Comparison with the
results of similar panic studies shows bipolar disorder is associated with
enhanced respiratory response to CO2. Hypersensitivity to CO2 among bipolar
individuals suggests a possible pathological mechanism common to both bipolar
and panic disorders. These preliminary data support the expanded application of
CO2 challenges in bipolar subjects.