Death of The Hypoxic Drive Theory

Three calls so far:

An old man with weakness in one of his legs times three days. He was a bit testy and didn't like answering questions. At the hospital, he told them he had gout.

We took an 80 year old lady with shortness of breath in. She had a COPD history, but wasn't wheezing. She'd just come out of the hospital following a five day stay in the critical care wing for heart, lung and kidney problems. She was short of breath even on a cannula, so I put her on a mask. The nurse said she had been belching, which can be a sign of an inferior MI. Her twelve lead had no significant ST changes, but she had all the conditions for a silent MI -- female, elderly, diabetic, ex-smoker, high cholestrol, cardiac history. I'll be interested to follow up on her.

Both the nurse on scene and the nurse at the hospital were concerned about having the patient on 02 by mask given her COPD history. I didn't go into it with them, but in addition to the EMS tenet that no one who needs it shall be deprived of oxygen, I came across an interesting article by a respiratory therapist named Jeff Whitnack called:

The Death of The Hypoxic Drive Theroy

Very interesting reading. Here's an excerpt:

In the May 98 issue of Clinical Pulmonary Medicine is an article titled Acute Respiratory Failure in Chronic Obstructive Pulmonary Disease” by Schiavi. In it the author concludes that…… “....The traditional idea that oxygen induces hypoventilation by suppressing hypoxic ventilatory drive at the level of peripheral chemoreceptors is no longer tenable.”

Here's the guy's home page, which includes a link to his powerpoint presentation.

Jeff Whitnack's RT Page

Last call was for decreased mental status in an elderly DNR patient with a COPD history. He was breathing in a strange way. He wouldn't open his mouth, so his exhalation would puff up his cheek's like a frog, then the air would go up out his nose. It produced a capnography wave similar to a bronchospasm. When I made him open his mouth to breath, his wave form straightened up.

Last call was for a middle aged man with chest pain and heart palpitations. He was very diaphoretic and looked uncomfortable. I put him on the monitor -- saw a rate in the 180's, and followed it with a 12-Lead.

It looked regular to me at the time, so I tried 6 mg of Adenosine, which briefly slowed it to reveal an irregular underlying rythmn, then he was back up in the 180's.

I gave him 25 mg of Cardizem. He was a big man and I was thinking maybe I should even give him a little more. His weight could have taken 30 mg in a first dose. The 25 worked.

My partner took a sharp turn and I dumped the contents of my med kit on the floor. I was a little late preparing a Cardizem drip. I got it hung as we pulled in to the hospital and was running it at 5 mg hour, then as we were wheeling him down the hall, he went back up into a rapid afib. I opened up the drip and tried squeezing it in, but he stayed up. I had about 15 mg in, when I turned over care. I came back from writing my report and he was finally back down in the 70's without any more meds than the drip.

Here's the heart rate trend summary, a feature I am just getting used to using: