Hypercapnia ventilatory response-Paula

Mammals respond to hypercapnia and hypoxia by increasing minute ventilation (Ve) to maintain a neutral balance of acid and base. Hypercapnia is the main driver of the ventilatory response. PLoS One. 2017; 12(1): e0168930 10.1371/journal.pone.0168930 Analysis of Hypoxic and Hypercapnic Ventilatory Response in Healthy Volunteers Shmuel Goldberg, et al

But it seems to me, that we do not know a lot about the failure of the airways and the skeletal respiratory muscle system system to respond adequately the increased needs of metabolism presented by disease. We know a lot more about the response of the system to increased needs of metabolism due to exercise and increased locomotor activity.

It seems that for Paula, the response to increased exercise is intact, perhaps due to the enhanced circulation of blood and the help of the lower body skeletal muscle pump involving the action of the legs and feet.

We have observed that Paula does not seem to have a normal response to increased metabolic needs when she is challenged by physical illness. Her breathing rate remains very slow and deep during respiratory partial obstruction and other respiratory challenges. This is worrisome, as the respiratory system is the first responder to a state of rising acids or hypercapnia.

We don’t think this has ever been studied because no one has studied the hypercapnic ventilatory responses of the ambulatory patient to rising acids due to various respiratory challenges caused by illness and polluted indoor or outdoor air. Theoretically, we know how a normal system responds. This does not seem to be the case for Paula.

And her abnormal breathing rate at rest seems to suggest a lack of flexibility when responding to acid base issues in the blood and/or in the brain.

 What are the signs and symptoms of hypercarbia?

Hypercarbia acts as a direct vasodilator in the systemic circulationand as a direct vasoconstrictor in the pulmonary circulation. It is also a direct cardiac depressant. Cerebral blood flow increases in proportion to arterial CO2. An increase in catecholamines is responsible for most of the clinical signs and symptoms of hypercarbia. Hypercarbia causes an increase in heart rate, myocardial contractility, and respiratory rate along with a decrease in systemic vascular resistance. Higher systolic blood pressure, wider pulse pressure, tachycardia, greater cardiac output, higherpulmonary pressures, and tachypnea are common clinical findings. In awake patients symptoms include headache, anxiety/restlessness, and even hallucinations. Extreme hypercapnia produces hypoxemiaas CO2 displaces O2 in alveoli. Matthew D. Coleman MD, in Anesthesia Secrets (Fourth Edition), 2011 Respiratory and Pulmonary Physiology

to to be continued…..

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