Year : 2023 | Volume
| Issue : 1 | Page : 107-109
Refractory hypertension after phenylephrine infusion in cesarean section under subarachnoid block
Vikash Bansal, Kirti N Saxena, Bharti Wadhwa
Department of Anaesthesiology and Critical Care, Maulana Azad Medical College, New Delhi, India
Flat No 259, Mirdard Colony, MAMC Campus, New Delhi
Source of Support: None, Conflict of Interest: None
|Date of Submission||21-Jun-2021|
|Date of Acceptance||28-Jun-2022|
|Date of Web Publication||02-Jan-2023|
A 21-year-old female was scheduled to undergo elective cesarean section for breech presentation under the subarachnoid block (SAB). The pre-operative examination was unremarkable and baseline vitals were normal. Under all aseptic precautions and American society of anesthesiologists standard monitoring, SAB was administered with 2.2 ml of 0.5% hyperbaric bupivacaine. Soon after administration of SAB, prophylactic infusion of phenylephrine was started at the rate of 50 μg/min; after pre-treatment with 0.2 mg glycopyrrolate intravenous immediately after the start of the infusion, the patient complained of severe headache. Blood pressure (BP) recorded at that time was 191/102 mm of Hg. Phenylephrine infusion was stopped immediately but the BP remained high and came to within 20% of baseline value only after 9 min of discontinuing the infusion. We report this case of refractory hypertension following phenylephrine infusion in a healthy parturient undergoing elective cesarean section under SAB.
Keywords: Glycopyrrolate, phenylephrine, refractory hypertension
|How to cite this article:|
Bansal V, Saxena KN, Wadhwa B. Refractory hypertension after phenylephrine infusion in cesarean section under subarachnoid block. Saudi J Anaesth 2023;17:107-9
|How to cite this URL:|
Bansal V, Saxena KN, Wadhwa B. Refractory hypertension after phenylephrine infusion in cesarean section under subarachnoid block. Saudi J Anaesth [serial online] 2023 [cited 2023 Mar 31];17:107-9. Available from: https://www.saudija.org/text.asp?2023/17/1/107/364852
| Introduction|| |
Hypotension is one of the major concerns when administering SAB in cesarean section as it significantly impairs both maternal and fetal outcomes. Prophylactic phenylephrine infusion for the prevention of hypotension during cesarean section is now the modality of choice. It has potent α receptor agonistic action without β adrenergic receptor activity and reduces the risk of hypotension and fetal acidosis., Its use is often associated with a dose-related reflexive slowing of maternal heart rate (HR) and a corresponding decrease in cardiac output,, which can be attenuated or prevented by using glycopyrrolate. As placental blood flow depends on the cardiac output which depends on stroke volume and HR.
| Case Report|| |
A 21-year-old parturient was posted for the elective cesarean section at 38 weeks of gestation. The pre-operative evaluation was unremarkable, with no comorbidity and no h/o hypertension and baseline vitals were normal. SAB was administered through the midline approach with 2.2 ml of heavy bupivacaine (0.5%). Soon after this, pre-treatment with glycopyrrolate (0.2 mg) was given intravenously and a prophylactic infusion of phenylephrine was started at the rate of 50 μg/min for prevention of SAB-induced hypotension. Within 2 min of the start of the infusion, the patient started complaining of severe headache and nausea. The blood pressure (BP) taken at that time was found to be 191/102 mm Hg. The phenylephrine infusion was stopped immediately and 2 min later BP came down to 173/102 mm Hg, and the patient headache was relieved. Subsequent BP reading was recorded and a consistent fall in the BP reading reaching 147/101 mm Hg after 9 min of stopping the infusion was achieved, which was within 20% of baseline BP (128/76 mm Hg). There were no episodes of maternal bradycardia at any time. The rest of the surgery proceeded uneventfully and a healthy baby was delivered with Apgar scores of 9 and 9 at 1 and 5 min, respectively, with a normal umbilical cord pH. The total consumption of phenylephrine during the 2 min period of infusion was 2 ml 100 μg. The parturient was followed up in the post-operative period and investigated for other causes of refractory hypertension. Patients who are hyperthyroid, hypertensive, or taking monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants might have an accelerated response even to a lower dose of phenylephrine. All relevant investigations including work up for pheochromocytoma were undertaken and none of them was found to be significant.
| Discussion|| |
Hypotension is the most common side effect after SAB in parturients undergoing cesarean section which has serious maternal and fetal implications. Prophylactic phenylephrine infusion is considered the drug of choice for the prevention of post-spinal hypotension as it is easily titrable and does not cause rebound hypo- or hypertension after discontinuing the infusion and action usually terminates within 2–3 min after stopping the infusion., Various doses of phenylephrine infusion from ranging 25 to 200 μg/min have been used in the parturient and episodes of hypertension following prophylactic infusion doses greater than 50 μg/min have been reported.,, In our case prophylactic phenylephrine was started at the rate of 50 μg/min, and pre-treatment with glycopyrrolate 0.2 mg bolus was given but even with this optimal dose our patient developed severe headache with a sudden rise in BP lasting as long as 9 min even after discontinuing the infusion immediately in a previously healthy parturient. This was an unusual finding since the BP usually comes down to 20% of baseline values within 2–3 min of discontinuation of phenylephrine infusion and such episodes of hypertension have not been reported with infusion doses of 50 μg/min. The hypertensive episodes lasted for 9 min but the fetal outcome was unaffected as the umbilical cord gas analysis and Apgar scores of the baby were found to be normal and the patient was asymptomatic thereafter. Phenylephrine ampoules have a concentration of 10 mg/ml and for making a solution of 50 μg, careful serial dilutions are required, initially we thought that there might have been an error in dilution and a higher dose of phenylephrine may have got administered but a careful cross-check revealed that there had been no error in the dilution of the drug. The patient was followed up after the surgery to investigate for any underlying cause that may have contributed to this refractory hypertension. Patients who are hyperthyroid, hypertensive, or taking MAOIs and tricyclic antidepressants might have an accelerated response even to a lower dose of phenylephrine. All relevant investigations including work up for pheochromocytoma were undertaken and none of them was found to be significant.
While episodes of hypertension have been reported with prophylactic phenylephrine, they are usually of short duration, relieved within minutes of stopping of infusion, and without maternal and fetal implications.,, Our patient was a healthy young parturient who developed symptomatic refractory hypertension following standard prophylactic phenylephrine infusion for prevention of post-spinal hypotension. Exaggerated BP might be due to a combination of phenylephrine and glycopyrrolate as the latter also have some intrinsic hypertensive properties.
| Conclusion|| |
Refractory hypertension as seen in our case has not been reported after phenylephrine infusion. We suggest that a high level of vigilance be maintained in monitoring the patient when using such infusion and a further reduction in prophylactic doses may be considered to prevent the occurrence of hypertensive episodes ensuring maternal and fetal safety.
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Conflicts of interest
There are no conflicts of interest.
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