Wednesday, December 25, 2013

Case scenarios: When you don't give patients 100% O2 and why

Clinical scenario #1: Chronic lung disease patient.

The ventilatory drive of patients with chronic lung disease is primary due to their hypoxemia, rather than CO2 levels. This is because pCO2 receptors are adaptive. Chronically elevated pCO2 makes central receptors unresponsive in COPD patients. Administration of a high O2 mixture to relieve the hypoxemia is contraindicated because this removes the hypoxic drive, leading to severe hypoventilation.

Clinical scenario #2: Drug overdose where central receptors are blocked.
In morphine or heroine overdosed patients, central receptors are knocked out and the hypoxic drive is what keeps them breathing. Administration of a 100%  O2 mixture to relieve the hypoxemia is contraindicated too because this removes the hypoxic drive which kept them breathing.

Clinical scenario #3: Tracheostomy following prolonged respiratory obstruction.

Apnea in patients is due to washing out of CO2 which was acting as a respiratory stimulus. Treatment is to administer 5% CO2 in oxygen or assisted ventilation.

Clinical scenario #4: Premature babies.

Preemies (especially, before 32 weeks corrected gestational age) should be maintained on just enough oxygen to maintain O2 saturation between  85-95% (the exact range varies, but you get the picture).
Extra oxygen can worsen retinopathy of prematurity and lead to blindness. Giving 100% O2 to preemies with  hyaline membrane disease can also cause barotrauma leading to increased borderline personality disorder.
Credits: clumsy-medic & baffledinbrooklyn

I know there are many such scenarios but I can't think of any more at the moment. The basic concept in such cases is the same - understanding which receptor acts as a drive for respiration and not messing with it! Lemme know if you recall any more and we'll add more scenarios here =)

Merry Christmas everyone! < 3

Updated on 3rd Jan, 2014: Scenario #4

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