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Tracheal constriction by morphine and by fentanyl in man
Anesthesiology
|August 1, 1978
Summary
Morphine and fentanyl, potent analgesics, cause tracheal smooth muscle constriction during anesthesia induction. This effect can be blocked by specific medications, suggesting a need for careful drug selection in patients with respiratory conditions.
Area of Science:
- Anesthesiology
- Pharmacology
- Respiratory Physiology
Background:
- Opioid analgesics like morphine and fentanyl are commonly used during anesthesia.
- Their effects on airway smooth muscle tone are not fully understood.
- Tracheal smooth muscle plays a role in maintaining airway patency.
Purpose of the Study:
- To investigate the effects of morphine and fentanyl on tracheal smooth muscle tone.
- To determine if these effects can be antagonized by other drugs.
Main Methods:
- 38 patients undergoing anesthesia induction.
- Tracheal smooth muscle tone measured by endotracheal tube cuff pressure.
- Administration of morphine (0.5 mg/kg) or fentanyl (0.006 mg/kg).
- Assessment of effects with and without atropine or droperidol pretreatment.
Main Results:
- Morphine caused a biphasic response: initial dilation followed by significant constriction (21 +/- 8% increase in cuff pressure).
- Fentanyl also caused significant tracheal constriction (44 +/- 11% increase in cuff pressure).
- Morphine-induced constriction was blocked by atropine; fentanyl-induced constriction was blocked by droperidol.
Conclusions:
- Both morphine and fentanyl cause significant tracheal smooth muscle constriction at equianalgesic doses.
- These constrictor effects can be antagonized by atropine and droperidol, respectively.
- Clinical implications for airway management during anesthesia, particularly in patients with potential for bronchospasm.