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Journal of Obstrectic Anaesthesia and Critical Care
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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 9  |  Issue : 2  |  Page : 70-74

Anesthetic management of idiopathic pulmonary arterial hypertension for cesarean section – experiences from a tertiary care center


Department of Anaesthesiology and Critical Care, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, Kerala, India

Date of Submission17-Jan-2019
Date of Acceptance14-Mar-2019
Date of Web Publication06-Sep-2019

Correspondence Address:
Dr. Nitu Puthenveettil
Department of Anaesthesiology and Critical Care, Amrita Institute of Medical Sciences, Amrita Vishwa Vidyapeetham, Kochi, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/joacc.JOACC_4_19

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  Abstract 


Introduction: Idiopathic pulmonary arterial hypertension (IPAH) is a rare cardiac disease. Recent studies have shown a decline in mortality due to the incorporation of PAH-specific therapy. Objective: The aim of our study was to examine the anesthetic management of patients with IPAH, who presented for cesarean section and to know the outcome of pregnancy. Materials and Methods: This is a retrospective observational review, where we have studied the maternal and fetal outcome and anesthetic management of IPAH who underwent elective cesarean section in a tertiary care center from 2010 to 2018. The demographic variables of the patient, details of pregnancy, maternal, and fetal outcome were analyzed. Results: All five patients studied had severe pulmonary arterial hypertension. Our maternal mortality rate was 20%. Except for one patient, all others received regional anesthesia. All patients went on inotropic support following induction, which was gradually tapered. Pulmonary artery catheter was not used in any of our patients. None of the patients required postoperative ventilation. Two babies were shifted to neonatal the intensive care unit in view of poor Apgar scores. Conclusion: Multidisciplinary approach involving cardiologist, obstetrician, and anesthetist is required in planning and management of these high-risk obstetric patients. Epidural anesthesia seems to be an alternative to general anesthesia for cesarean section. The risks versus benefit of pulmonary arterial catheter should be considered before its insertion. Despite all treatment efforts, maternal mortality is high. Hence, pregnancy should be discouraged, and preconceptional counseling and medical abortion should be offered if patient presents early or shows signs of deterioration.

Keywords: Cesarean section, idiopathic pulmonary arterial hypertension, maternal mortality, pregnancy, regional anesthesia


How to cite this article:
Puthenveettil N, Paul J, Moorthy S, Kumar L. Anesthetic management of idiopathic pulmonary arterial hypertension for cesarean section – experiences from a tertiary care center. J Obstet Anaesth Crit Care 2019;9:70-4

How to cite this URL:
Puthenveettil N, Paul J, Moorthy S, Kumar L. Anesthetic management of idiopathic pulmonary arterial hypertension for cesarean section – experiences from a tertiary care center. J Obstet Anaesth Crit Care [serial online] 2019 [cited 2019 Nov 14];9:70-4. Available from: http://www.joacc.com/text.asp?2019/9/2/70/266148




  Introduction Top


Idiopathic pulmonary arterial hypertension (IPAH) also known as primary pulmonary hypertension is defined as mean pulmonary pressures >25 mmHg at rest or >30 mmHg during exercise, associated with a pulmonary capillary wedge pressure less than 12 mmHg diagnosed by right heart catheterization in the absence of any secondary causes.[1] Pregnancy in patient with IPAH is associated with high maternal mortality, hence not recommended.[2],[3] The physiological changes that normally occur in pregnancy and postpartum period are not tolerated in these patients.[4] Introduction of advanced therapy and multidisciplinary approach toward managing these high-risk patients have improved their outcome.[5] Hence, more patients survive to become pregnant and require anesthetic care. IPAH is a rare cardiac disease with poor outcome during pregnancy. Hence, even though our center is a tertiary care hospital with pediatric cardiology and high-risk obstetric unit, we have encountered only five such patients in the past 8 years.


  Materials and Methods Top


After approval from the hospital ethics committee, in this retrospective observational review, we studied the obstetric case records of five patients with IPAH who underwent elective cesarean section in a tertiary care center from 2010 to 2018. We studied the maternal and fetal outcome and anesthetic management of these high-risk patients. The demographic variables, details of pregnancy, preoperative maternal evaluation by New York Heart Association classification, signs and symptoms, echocardiographic assessment, medications (prostonoids, calcium channel blockers, oral anticoagulants), anesthetic management (general or regional), intraoperative monitoring, hemodynamic supports, number of days of hospital and intensive care unit (ICU) stay, maternal complications, and fetal outcome were noted. Neonatal outcomes studied included Apgar score, birth weight, and neonatal ICU admission.


  Results Top


All the five patients studied had severe pulmonary arterial hypertension [Table 1] and [Figure 1]. Our maternal mortality rate was 20%. Except for the first patient, all the others received regional anesthesia. Invasive central line and arterial line were used for all our patients. Pulmonary artery catheter was not used in any of our patients. All the patients went on inotropic support that was gradually tapered in the ICU. Two babies were shifted to neonatal ICU in view of poor Apgar scores [Table 2].
Table 1: Patient data

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Figure 1: Echocardiographic picture of a patient with pulmonary artery hypertension

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Table 2: Anesthetic outcome

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  Discussion Top


Although mortality rate among parturients with IPAH has decreased in the past decade, the number still remains high. Even with a multidisciplinary approach in the management of these patients, we had a 20% maternal mortality rate (one of five patients). Mortality in a pregnant patient with IPAH has declined from 36% to 28% due to incorporation of PAH-specific therapy.[3] Prostacyclin analogs, phosphodiesterase inhibitors, and endothelin receptor antagonist are used in the treatment of IPAH. High-dose calcium channel blockers can reduce pulmonary artery pressure in 5%–10% of patients with IPAH. Diuretics are prescribed for patients with right ventricular (RV) failure. Patients with IPAH with functional New York Heart Association class 3 and 4 showed improved survival and quality of life with intravenous infusions of prostacyclin.[6] All our patients received advanced therapy with sildenafil/tadalafil ± prostonoids during pregnancy.

Normal pulmonary arterial pressure is 12–16 mmHg. Pulmonary artery hypertension is defined as a mean pulmonary artery pressure (mPAP) greater than 25 mmHg at rest. The World Health Organization has classified pulmonary hypertension (PH) into five groups: arterial, venous, hypoxic, thromboembolic, or miscellaneous.[7] IPAH belongs to the first group. Pulmonary artery pressures and pulmonary capillary wedge pressures can only be measured accurately by right heart catheterization. Right heart catheterization also helps identify the vasoreactivity, to identify patients who would benefit from long-term therapy with calcium channel blockers. Right heart catheterization is considered as gold standard in diagnosing PH except in pregnancy because of the risk involved.[8] mPAP can be roughly calculated from systolic pulmonary artery pressure (sPAP) of echocardiogram reports (mPAP = 0.61 × sPAP + 2).[9]

In normal pregnancy due to physiological changes, pulmonary vascular resistance (PVR) decreases and cardiac output increases. In IPAH, there is vasoconstriction of blood vessels connected to the lungs. This increases the cardiac load, which causes the right ventricle to hypertrophy, ultimately causing right heart failure.[10] Sudden death from dysrhythmia can occur in these patients. There is decreased blood flow through the lungs and the left side of the heart receives poorly oxygenated blood, decreasing oxygen supply to the rest of the body. Pain and valsalva maneuver during labor stimulates the sympathetic nervous system resulting in increase in heart rate, blood pressure, and myocardial oxygen consumption. RV volume overload can occur easily as around 500 mL of blood is pushed into maternal circulation with each contraction. Moreover, autotransfusion that occurs after delivery can lead to large fluid shifts.[7]

The mode of delivery to be chosen is controversial. Some centers advocate planned cesarean section at 34 weeks under regional anesthesia. Whereas some other studies showed better outcome with vaginal delivery.[10] Better results obtained with normal vaginal delivery could be due to the fact that patients with less severe disease would have been allowed to deliver vaginally. Labor epidural analgesia can be provided to patients if vaginal delivery is planned. All patients with IPAH who reported to our hospital were delivered by cesarean section. Except for the first patient who died, all others were taken electively.

Preinduction invasive arterial line and central line monitoring, five-lead electrocardiogram, and saturation probe are required. The central line was inserted to start inotropic support and to monitor the trend in central venous pressure (CVP), as CVP is not reliable in patients with PH. The use of pulmonary arterial catheter (PAC) is controversial because of the risk of arrhythmia, pulmonary artery rupture, and embolization.[11],[12],[13] We did not use PAC in the management of any of our patients. Noninvasive cardiac output monitor if available could have been used to record stroke volume, stroke volume variation, systemic vascular resistance, and cardiac output.[14]

The choice of anesthesia is controversial. General anesthesia combined spinal epidural or plane epidural could be used for cesarean delivery. Recent studies show that regional technique is preferred [Table 3]. Patients receiving general anesthesia were four times more likely to die than patients receiving regional anesthesia.[7] General anesthesia may be required in severe cases where a patient cannot lie supine. Use of general anesthesia also helps better control the use of nitric oxide.[19] Infusions of noradrenalin and phenylephrine should be loaded and connected to the central line to support systemic circulation before induction. Narcotic-based technique is used for induction of general anesthesia, but has the disadvantage of slow induction in a patient with full stomach and can cause neonatal respiratory depression. Use of nitrous oxide is avoided as it is a cardiodepressant and it increases PVR. Another disadvantage of general anesthesia is that positive pressure ventilation produces undesirable hemodynamic effects and reduces pulmonary blood flow. Care has to be taken in maintaining temperature, acid–base balance, and oxygen and carbon dioxide levels within the normal range. Incremental regional anesthesia helps in maintaining a better hemodynamic in these group of patients.[12] Hypotension that develops after a regional technique should be aggressively managed with phenylephrine and/or noradrenalin infusions to avoid decreased RV coronary perfusion.
Table 3: Comparison with other studies

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Oxytocin boluses at the time of delivery should be avoided as it can cause hypotension by systemic vasodilation and also increase PVR.[20] Small doses of oxytocin can be used as infusions to augment uterine contraction after delivery of the baby. Use of ergometrine and prostaglandin F2α is contraindicated in PH as they are known to cause pulmonary vasoconstriction. In contrast, PGE1 is known to cause pulmonary vasodilaton.[19]

In our study group, first the patient was shifted from cardiac ICU in propped up position with oxygen being supplemented through facemask. She was not comfortable in supine position. Hence, general anesthesia was planned; central line and arterial line were inserted preinduction. Opioid induction was performed with 3 μg/kg of fentanyl and 20 mg of propofol. She was paralyzed with succinyl choline, intubated, and maintained on O2, air, and isoflurane. Muscle paralysis was maintained with atracurium. Ionotropic supports (noradrenalin and phenylephrine infusion) were loaded and connected to the central line. But hemodynamics was stable following induction. Soon after baby delivery, oxytocin 5IU was started by slow intravenous infusion. The patient gradually developed bradycardia and there was a drop in blood pressure. Intravenous atropine, ephedrine, and adrenaline were given with no signs of improvement. Cardiopulmonary resuscitation (CPR) was started. Cardiac anesthetist and cardiology team were called. Pacemaker was inserted. But even after 1 hour of CPR, the patient could not be revived. We speculate that sudden autotransfusion and decompression of IVC along with the use of infusion of oxytocin could have resulted in volume overload to an already dilated, pressure-loaded RV, worsening RV systolic function. As a result of this incident, we modified our management. We started using regional techniques, started keeping NO ready in the theater and involving cardiac anesthetist and cardiologist in the management of such high-risk cases. Our patients are also counseled regarding the requirement of sterilization to avoid further pregnancies.

The second patient was not symptomatic at rest and so a decision of performing combined spinal epidural was taken. A low-dose spinal with 5 mg of heavy bupivacaine and 20 μg fentanyl was given. There was drop in blood pressure which was managed with phenylephrine boluses and noradrenalin infusion. Epidural infusion with 0.5% bupivacaine was started to maintain anesthesia. Care was taken to avoid a drop in mean arterial pressure to <20% of baseline. The remaining three patients underwent cesarean section under epidural anesthesia as we expected the hemodynamic to be more stable with epidural alone. After a test dose of 3 mL of 2% lignocaine with adrenaline, graded epidural with small aliquots of 0.5% bupivacaine (3–5 mL) was used to achieve adequate level of anesthesia. A total of 8–12 mL was given over 15–20 min. But these patients also required noradrenalin infusions (0.05–0.2 μg/kg/min) to maintain the blood pressures, which was tapered in the ICU over 3–4 h, when the patients' baseline blood pressures were achieved. The epidural was removed in the postoperative period and the patients were started on low-molecular-weight heparin (LMWH) 12 h postoperatively.

Postoperative pain was managed with intravenous opioids and paracetamol. Postoperative course of these patients was uneventful.

The babies born to IPAH also have a poor outcome because of the high rates of preterm delivery, intrauterine growth retardation, and perinatal mortality. Our neonatal survival rate was 100%. Two babies were shifted to neonatal ICU in view of poor Apgar score, and one of the babies was on ventilator. Postoperatively, all patients were intensively monitored in the ICU. Use of anticoagulation is highly recommended in these group of patients.[21] All patients in our series were anticoagulated with subcutaneous LMWH. This was continued for 6–12 weeks after delivery. We did not encounter any thrombotic complications during pregnancy or in the puerperium.


  Conclusion Top


Multidisciplinary approach involving cardiologist, obstetrician, and anesthetist is required in planning and management of these high-risk obstetric patients. Epidural anesthesia seems to be an alternative to general anesthesia for cesarean section in patients with IPAH. The risks versus benefit of PAC should be considered before its insertion, and newer noninvasive or semi-invasive modalities could be used for better patient outcome. Despite all the treatment efforts, maternal mortality is high. Hence, pregnancy should be discouraged in these patients, and preconceptional counseling about risks of pregnancy and medical abortion should be offered if the patient presents early or show signs of deterioration.

Acknowledgements

The authors acknowledge Dr Aveek Jayan for helping us in completing this article.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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