A patient is given 200mcg of fentanyl on induction. What happens to the oxyhemoglobin dissociation curve and the carbon dioxide blood dissociation curve?

When a patient receives 200 mcg of fentanyl, it can have significant effects on the respiratory system, particularly in terms of oxygen and carbon dioxide transport. The correct response indicates that the oxyhemoglobin dissociation curve shifts to the right and the carbon dioxide dissociation curve shifts up and to the left.

The shift of the oxyhemoglobin dissociation curve to the right indicates a decreased affinity of hemoglobin for oxygen. This means that, at a given partial pressure of oxygen, hemoglobin will release more oxygen to the tissues. Fentanyl, as an opioid, can lead to respiratory depression, which may encourage this rightward shift due to increased carbon dioxide levels in the blood from reduced ventilation. Higher levels of carbon dioxide and lower pH (more acidity) favor the release of oxygen from hemoglobin.

In the case of the carbon dioxide dissociation curve, a shift upwards and to the left suggests an increased ability of blood to carry carbon dioxide back to the lungs for expiration at given partial pressures. Opioids like fentanyl can affect the body's response to carbon dioxide, potentially enhancing its release from the blood as the patient may retain more carbon dioxide due to decreased respiratory drive.

These physiological responses highlight the influence of fentanyl on gas exchange