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Increased blood pressure following pupillary dilation with 2.5% phenylephrine hydrochloride in preterm infants
Insights
Instilling pupillary dilators like tropicamide and phenylephrine in preterm infants caused no heart rate changes but significantly increased blood pressure. Monitor infant blood pressure during mydriatic drug use.
Area of Science:
- Neonatal physiology
- Ophthalmology
- Pharmacology
Background:
- Preterm infants are vulnerable to hemodynamic changes.
- Mydriatic agents are used for ophthalmic examinations.
Purpose of the Study:
- To evaluate cardiovascular effects of tropicamide and phenylephrine in preterm infants.
- To assess the safety of these mydriatic drugs in neonates.
Main Methods:
- Continuous monitoring of heart rate and blood pressure in seven preterm infants.
- Measurement before and after instillation of 0.5% tropicamide and 2.5% phenylephrine.
- Observation period of 30 minutes pre-instillation and 75 minutes post-instillation.
Main Results:
- No significant changes in heart rate were observed.
- A significant increase in systolic, diastolic, and mean arterial blood pressure occurred.
- Elevated blood pressure peaked at 8 minutes and persisted for 30 minutes post-instillation.
Conclusions:
- Tropicamide and phenylephrine cause significant, albeit temporary, increases in blood pressure in preterm infants.
- Close monitoring of arterial blood pressure is crucial during mydriatic drug administration in this population.
- Potential link between elevated blood pressure and intraventricular hemorrhage warrants caution.
Abstract:
Heart rate and blood pressure changes following 0.5% tropicamide and 2.5% phenylephrine hydrochloride were evaluated in seven ill preterm infants (birth weight, 910 to 2,060 gm; gestational age, 26 to 36 weeks) during the first day of life. Each infant was monitored continuously for 30 minutes before and for 75 minutes after, instillation of the pupillary dilators. There were no significant changes in the heart rate, whereas a significant increase in systolic, diastolic, and mean arterial blood pressure was found. The increase in arterial blood pressure was detected at two minutes, peaked at eight minutes, and remained at significantly higher levels for 30 minutes after instillation. Because of the potential relationship between increased blood pressure and intraventricular hemorrhage, arterial blood pressure must be monitored during instillation of mydriatic drugs in the preterm infant.