Journal of Obstetric Anaesthesia and Critical Care

: 2020  |  Volume : 10  |  Issue : 2  |  Page : 149--150

Attenuation of autonomic responses to laryngoscopy and intubation with intravenous nitroglycerin in a patient with severe preeclampsia and pulmonary edema undergoing cesarean section

Patchareya Nivatpumin 
 Department of Anesthesiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand

Correspondence Address:
Dr. Patchareya Nivatpumin
Department of Anesthesiology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Wanglang Road, Bangkok - 10700

How to cite this article:
Nivatpumin P. Attenuation of autonomic responses to laryngoscopy and intubation with intravenous nitroglycerin in a patient with severe preeclampsia and pulmonary edema undergoing cesarean section.J Obstet Anaesth Crit Care 2020;10:149-150

How to cite this URL:
Nivatpumin P. Attenuation of autonomic responses to laryngoscopy and intubation with intravenous nitroglycerin in a patient with severe preeclampsia and pulmonary edema undergoing cesarean section. J Obstet Anaesth Crit Care [serial online] 2020 [cited 2021 Jan 15 ];10:149-150
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Full Text

Dear Editor,

I would like to report the case of a patient suffering from severe preeclampsia with pulmonary edema undergoing urgent cesarean delivery.

A 35-year-old G2P1 female with a gestational age of 31 + 5 weeks (92 kg, 154 cm) developed shortness of breath and could not lie flat on her back for 1 week prior to her arrival at our center. She had no known underlying disease. At the labor ward, her physical examination revealed blood pressure (BP) of 180/100 mmHg, heart rate (HR) 100 bpm, oxygen saturation 88%, tachypnea, orthopnea, pitting edema 2+ in both legs, fine crepitation in both lungs, and heart sounds of systolic ejection murmur grade 2 at the apex. Laboratory investigation revealed urine protein 1+ and urine protein to creatinine ratio (UPCR) 11.2. Intravenous furosemide was incrementally administered 20 mg up to 80 mg. Intravenous dexamethasone, magnesium sulfate, and hydralazine were also given.

Portable chest X-ray (CXR) revealed marked cardiomegaly with pulmonary congestion [Figure 1]. Transthoracic echocardiogram performed by a cardiologist showed left ventricular ejection fraction (LVEF) of 61%, concentric left ventricular (LV) hypertrophy, cardiac output at left ventricular outflow tract (LVOT) 5.4 L/min, and moderate mitral valve regurgitation due to billowing of the leaflet. The patient was then prepared to undergo an urgent cesarean section due to severe preeclampsia with maternal pulmonary edema.{Figure 1}

In the operating theatre, her BP was 210/110 mmHg, HR 96 bpm, and electrocardiogram (ECG) showed sinus rhythm. She was unable to lie flat on her back. Her oxygen saturation was 95% with an oxygen mask delivering 10 L PM. Arterial line insertion was performed under local anesthesia before the induction of anesthetic. A central venous line was not been inserted in this patient. Intravenous nitroglycerin was commenced at a rate of 3 mcg/kg/min, with subsequent uptitration upto 10 mcg/kg/min. The patient's systolic blood pressure (SBP) decreased to 140–150 mmHg within approximately 5–7 min after IV nitroglycerin administration. Thiopental 150 mg, etomidate 20 mg, and succinylcholine 100 mg were used for rapid sequence induction. During and immediately after intubation, her peak SBP was approximately 120–140 mmHg with no intubation-related difficulties or complications. Intravenous nitroglycerin was discontinued after intubation to forestall uterine relaxation after delivery. Anesthesia was maintained with 100% oxygen and sevoflurane and cisatracurium. After delivery sevoflurane was ceased and propofol infusion was used for maintaining anesthesia. Bispectral index monitoring (BIS) was used revealing BIS level of 45–55 throughout the operation. Intraoperative oxygen saturation was 93%–98% after volume control ventilation with a tidal volume of 450–500 mL, respiratory rate 12–14/min and positive end-expiratory pressure of 10 cm H2O; peak airway pressure was 27–30 cm H2O. Intravenous midazolam was administered after delivery. Fentanyl and morphine were also given as analgesic agents. The increment dosage of oxytocin bolus up to 10 units was slowly given in a 15-min period. Infusion of oxytocin and magnesium sulfate were continually given. Intraoperative peak SBP was 160 mmHg. Intravenous nicardipine was then given and her SBP was maintained between 110–130 mmHg during the cesarean section procedure. The baby had a birth weight of 1,550 gm, and the 1-min, 5-min, and 10-min Apgar scores were of 1, 4, and 8, respectively. The patient was not extubated because of the awareness of the oxygenation problem and was transferred to the intensive care unit (ICU). There she received 40 mg of furosemide and intravenous nicardipine to control hypertension. Her SBP was 150–170 mmHg/DBP 90–110 mmHg. She was extubated 26 h after surgery and she was discharged from the ICU and hospital on postoperative day 2 and day 8, respectively without other complications. Her medications at the discharge day were oral amlodipine and enalapril.

General anesthesia for cesarean delivery is required in patients with pulmonary edema that are unable to lie flat on their back.[1] However, hypertensive crisis during the intubation period should be avoided since this condition can lead to intracerebral hemorrhage, which is the major cause of death in preeclamptic patients.[2] The author used etomidate as an induction agent in order to keep stable hemodynamic together with the usage of low dose thiopental as a supplement agent due to her large bodyweight. Hood et al. reported that nitroglycerin successfully blunted the hypertensive response to endotracheal intubation in severely preeclamptic patients without fetal effects.[3] In addition, intravenous nitroglycerin is an effective agent for blunting autonomic response to laryngoscopy due to its rapid onset of action, its short duration of action, and the fact that it is a venodilator that is suitable for use in pulmonary edema patients.[4],[5] However, due to its prompt action, nitroglycerin should be used with extreme caution only by experienced physicians to prevent a precipitous decline in maternal blood pressure.[5] Moreover, since nitroglycerin is a known promotor of uterine relaxation, this medication was stopped after intubation to prevent uterine atony.

In conclusion, the author reports the successful use of intravenous nitroglycerin to attenuate the hypertensive response to laryngoscopy instead of using other medications such as labetalol, which is not proper in pulmonary edema patients.

Direct patient consent could not obtain because the patient lives in another province. She did not come for postpartum follow up in our center. The author was unable to contact the patient. However, the author received permission documented from the hospital director to contribute patient's data including the patient's chest X-ray.

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