Dr Grant has accurately summarized the problem faced when hyperventilating a hypoventilator. During hyperventilation, what degree of ventilation as measured by the partial pressure of carbon dioxide is indicative of normal bellows and lung function? What degree of bellows weakness can be associated with hypoventilation, and what role do the hypoxic and hypercapnic respiratory drives have in that situation? Unfortunately, not every physician has the insight into the problem that Dr Grant has. The purpose of our report, "Hyperventilating the Hypoventilator," was to demonstrate that care must be used in the interpretation of hyperventilation blood gases.
As Dr Grant pointed out, one would suspect that persons with abnormal central control mechanisms and entirely normal bellows and lung functions would reduce their Pco2's to the low 20s with hyperventilation. This supposition is not documented by previous investigators. Even in the presence of severe bellows weakness, the patient in our