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  Table of Contents 
Year : 2018  |  Volume : 19  |  Issue : 2  |  Page : 78-80

Hypotension due to inadvertent rapid intravenous infusion of ritodrine in a preterm labor

1 Department of Anaesthesiology, Indira Gandhi Institute of Medical Science, Patna, Bihar, India
2 Department of Anaesthesiology, AIIMS, Patna, Bihar, India

Date of Submission11-Jul-2018
Date of Acceptance27-Sep-2018
Date of Web Publication15-Nov-2018

Correspondence Address:
Dr. Roshan Andleeb
Department of Anaesthesiology, Indira Gandhi Institute of Medical Science, Patna, Bihar
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/TheIAForum.TheIAForum_32_18

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In this case report, we report the anesthetic management of an emergency cesarean section of a parturient who presented with preterm labor and had inadvertently received rapid intravenous administration of ritodrine.

Keywords: Cesarean section, hypotension, preterm labor, ritodrine, spinal anesthesia

How to cite this article:
Andleeb R, Kumar R, Kumari B. Hypotension due to inadvertent rapid intravenous infusion of ritodrine in a preterm labor. Indian Anaesth Forum 2018;19:78-80

How to cite this URL:
Andleeb R, Kumar R, Kumari B. Hypotension due to inadvertent rapid intravenous infusion of ritodrine in a preterm labor. Indian Anaesth Forum [serial online] 2018 [cited 2023 May 30];19:78-80. Available from: http://www.theiaforum.org/text.asp?2018/19/2/78/245542

  Introduction Top

Preterm births account for 6%–10% of all births and are an important cause of perinatal mortality and morbidity.[1] Short-term use of tocolytic drugs is common practice to prolong pregnancy for at least 48 h to allow for administration of antenatal steroid and other therapies to be administered.[2],[3] Ritodrine, beta-sympathomimetic agent, is a commonly used tocolytic with high selectivity for uterine β2 receptors which facilitates uterine relaxation. Infusion of ritodrine like other β adrenergic agonists results in frequent side effects such as nausea, vomiting, dizziness, headache, hypotension, maternal and fetal tachycardia, pulmonary edema, chest pain, electrocardiographic (ECG) changes, and metabolic side effects.[4],[5]

  Case Report Top

We received a call for emergency cesarean section of a 28-year-old primigravida with 35 weeks 6 days of pregnancy having fetal distress. On arrival, we were told by the obstetrician that the patient had presented with preterm labor, therefore, ritodrine by intravenous (iv) infusion (100 mg, i.e., 2 ampoules in 500 ml of normal saline giving 200 μg ritodrine/ml) was started and maintained at 120 μ/min, i.e., 12 drops/min but had accidentally received a large rapid dose of ritodrine.

At that time, the patient's heart rate was 160/min, blood pressure (BP) was 60/54 mmHg, and she was complaining of nausea. Immediately, rapid infusion of iv fluid started and iv mephentermine 6 mg was given. After 1 L of Ringer lactate and 3 bolus dose of mephentermine (6 mg), her heart rate settled at 110–120/min and BP stabilized at 98–100/60–68 mmHg.

The cardiotocography was showing fetal distress so emergency cesarean was planned. As per the patient's medical file except a recent episode of sore throat, her present and history were insignificant. Her systemic examination and all routine blood investigations were also within normal limit. As NPO criteria were not fulfilled and the patient had a recent upper respiratory tract infection, it was decided to proceed with cesarean section under spinal anesthesia. Keeping in mind that hypotension is the physiologic consequence of spinal anesthesia, prophylactic infusion of mephentermine (150 mg in 50 ml 0.9 NS giving 3 mg mephentermine/ml) at a rate of 3 mg/min or 20 drops/min started. Before induction of spinal block, the patient had heart rate of 110 beats/min, ECG showed sinus rhythm, BP was 110/70 mmHg, and respiratory rate was 22/min regular. The chest was clear on auscultation with bilateral vesicular breath sounds, and SpO2 on room air was 99%.

Spinal anesthesia was given with the patient in left lateral position at the level L2–L3 interspace using a 26-gauge Quincke's spinal needle. Bupivacaine 0.5% (7.5 mg) 1.5 ml with 25 μg of fentanyl was injected intrathecally. Within 5 min of spinal block, BP dropped to 70/55 mmHg which was recovered to 100/65 mmHg with iv bolus of 6 mg mephentermine along with background infusion of the same. Intraoperatively, her heart rate was 100–120/min and BP was in the range of 100–116/68–80 mmHg after adjusting the infusion rate of mephentermine at 2–5 mg/min, after completion of surgery, the patient shifted to post anesthesia care unit for monitoring. Gradually, mephentermine was tapered off according to BP, and after 4 h, it was discontinued.

  Discussion Top

Ritodrine is a short-acting β-sympathomimetic agent with predominant effect on β2 receptors of the uterine smooth muscle. It relaxes the myometrium by activating the cyclic adenosine monophosphate-protein kinase signaling cascade that phosphorylates and inactivates myosin light-chain kinase a key enzyme in uterine contraction, it reduces the intensity and frequency of contractions. It also acts on β2 receptor of vascular smooth muscle and causes peripheral vasodilatation. In high doses, it may cause severe hypotension. Due to activation of cardiac β2 receptor or reflex response of peripheral vasodilatation, it causes tachycardia. When used as iv infusion in parturient, it may cause adverse effects such as nausea, vomiting, dizziness, headache to at times, serious side effects such as hypotension, maternal and fetal tachycardia, pulmonary edema, chest pain, and ECG changes.

In our case, the patient had accidentally received high dose of ritodrine leading to tachycardia and hypotension, which was initially managed with iv fluid and bolus dose of injection mephentermine. As our plan of anesthetic management was to give spinal block which itself cause hypotension hence we used low dose of injection bupivacaine along with injection fentanyl to minimize the hemodynamic changes and also started prophylactic infusion of mephentermine to counteract spinal-induced hypotension.

Ritodrine has been used for the premature labor because of its action on myometrium. It has been reported to cause pulmonary edema, arrhythmias, and sudden cardiac deaths when used as tocolytic.[6] It has β2-adrenergic activity and can cause vasodilatation, hypotension, and hyperglycemia. Many authors have reported decrease in cardiac output and systolic BP and pulse pressure at 40 and 60 min of ritodrine infusion, which might have been caused by decrease venous return.[7]

Mephentermine is readily available and is the most commonly used vasopressor to treat spinal anesthesia-induced hypotension. Few studies have been conducted to compared it with other vasopressors regarding its safety and efficacy.[8],[9] There is one study in pregnant women that compare mephentermine with ephedrine and phenylephrine for the management of spinal anesthesia-induced hypotension in obstetric patients.[9] In our case, hypotension induced by accidental rapid infusion of ritodrine which was managed by mephentermine and also its continuous infusion assisted in conducting a successful emergency cesarean section under spinal anesthesia.

  Conclusion Top

Ritodrine, a β sympathomimetic agent, commonly used to prevent preterm labor and is administered as a slow continuous infusion. Its rapid infusion can cause hypotension, maternal and fetal tachycardia, and chest pain.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Arias F, Rodriquez L, Rayne SC, Kraus FT. Maternal placental vasculopathy and infection: Two distinct subgroups among patients with preterm labor and preterm ruptured membranes. Am J Obstet Gynecol 1993;168:585-91.  Back to cited text no. 1
Gyamfi-Bannerman C, Thom EA, Blackwell SC, Tita AT, Reddy UM, Saade GR, et al. Antenatal betamethasone for women at risk for late preterm delivery. N Engl J Med 2016;374:1311-20.  Back to cited text no. 2
Society for Maternal-Fetal Medicine (SMFM) Publications Committee. Implementation of the use of antenatal corticosteroids in the late preterm birth period in women at risk for preterm delivery. Am J Obstet Gynecol 2016;215:B13-5.  Back to cited text no. 3
Li X, Zhang Y, Shi Z. Ritodrine in the treatment of preterm labour: A meta-analysis. Indian J Med Res 2005;121:120-7.  Back to cited text no. 4
Maitra N, ChristianV, Verma RN, Desai VA. Maternal and fetal cardiovascular side effects of Nifedipine and Ritodrine used as tocolysis. J Obstet Gynecol India 2007;57:1314.  Back to cited text no. 5
Benedetti TJ. Maternal complications of parenteral beta-sympathomimetic therapy for premature labor. Am J Obstet Gynecol 1983;145:1-6.  Back to cited text no. 6
Bieniarz J, Ivankovich A, Scommegna A. Cardiac output during ritodrine treatment in premature labor. Am J Obstet Gynecol 1974;118:910-20.  Back to cited text no. 7
Mohta M, Janani SS, Sethi AK, Agarwal D, Tyagi A. Comparison of phenylephrine hydrochloride and mephentermine sulphate for prevention of post spinal hypotension. Anaesthesia 2010;65:1200-5.  Back to cited text no. 8
Sahu D, Kothari D, Mehrotra A. Comparison of bolus phenylephrine, ephedrine and mephentermine for maintenance of arterial pressure during spinal anaesthesia in caesarean section – A clinical study. Indian J Anaesth 2003;47:125-8.  Back to cited text no. 9
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