To the Editor,
Interstitial lung diseases (ILD) are heterogeneous group of disorders causing inflammation and thickening of the alveoli eventually leading to pulmonary arterial hypertension (PAH) and cor-pulmonale. Women with ILD and severe PAH were historically advised to avoid or terminate pregnancy and permanent contraception should be considered.1 However, currently published data is limited, with varying maternal and fetal outcomes reported in these patient population.
We describe the case of a 37-year-old primiparous woman at 34 weeks gestation with biopsy proven idiopathic pulmonary fibrosis, PAH on 6 L/min oxygen at home, and has been controlled on single therapy with sildenafil 20 mg three times a day for the past 4 years. Sildenafil was held in the setting of her current pregnancy. Pulmonary function test showed restrictive pattern (forced expiratory volume in one second [FEV1] 23% predicted, normal FEV1/forced vital capacity ratio) with severe diffusing capacity impairment (diffusing capacity for carbon monoxide 25% predicted). Ejection fraction was preserved on echocardiography 65–70% with elevated pulmonary artery pressure 40 mmHg, pulmonary vascular resistance (PVR) 310 dynes/cm-5. Chest CT showed diffuse mosaic attenuation with traction bronchiectasis changes.
Pregnancy course was complicated by preeclampsia with severe features. She was admitted to the intensive care unit (ICU) with shortness of breath and hypercapnic respiratory failure. Bi-level positive air pressure (BiPAP) auto-titration was instituted. Operative delivery plans were discussed with the multidisciplinary team—that included obstetrician, maternal fetal medicine, obstetric anesthesiology, neonatology, and pulmonology/critical care.
Our anesthetic goal was to utilize obstetric anesthetic method that will avoid any increase in the PVR, with the objective to minimize pain, sympathetic stimulation, hypoxia, hypercarbia, and acidosis. A low dose combined spinal epidural technique was selected. Spinal anesthesia was performed at L3–4 level with 1 mL of 0.75% hyperbaric bupivacaine along with 10 mcg of fentanyl. An epidural catheter was placed without test dose. She was maintained on BiPAP (15/5), Saturation maintained above 95% throughout the case. Invasive hemodynamic monitoring with an arterial line was placed, and pre-existing PICC was utilized for volume resuscitation. Extracorporeal membrane oxygenation circuit and pulmonary artery catheter were on standby should hemodynamic collapse ensues.
Vasopressor support was initiated with 2 unit/hr of vasopressin and then 2 mcg/min norepinephrine was added to maintain mean arterial pressure above 65 mmHg. Above vasopressor regimen was selected because, while vasopressin has systemic vasoconstrictive properties, it has not been shown to affect PVR and at lower doses it causes pulmonary vasodilatation.2 Norepinephrine on the other hand, decreases the ratio of pulmonary arterial pressure to systemic blood pressure without a change in cardiac index (when compared to phenylephrine), and is widely favored. Unlike norepinephrine, other vasoactive medications such as epinephrine, isoproterenol, and dobutamine with strong β-1 agonist effect may lead to tachycardia. Patients with PAH may be severely vulnerable to the adverse effect of tachycardia on diastolic filling time. Administration of dopamine is also associated with high risk of tachyarrhythmias, with a potentially fatal consequence in patients with PAH.3
Post-operatively, patient was transferred to ICU with venti-mask, vasopressors weaned off and pain control was achieved via continuous epidural infusion 10 cc/hr with a 0.0625% of bupivacaine.
In conclusion, pregnancy remains a significant cause of morbidity and mortality in PAH patient; however, pregnancy outcomes in PAH patients has improved when PAH is well controlled pre-conception with specific therapies, and PVR is being maintained.4 Thus, anesthetic plan should be individualized. No specific anesthetic plan is exclusive to these patient populations. Although neuraxial anesthetic technique is preferred for cesarean delivery, with the advantage of being able to maintain spontaneous ventilation, avoiding sympathetic stimulation and a potential difficult airway scenario with increases in PVR during laryngoscopy; anticoagulation use and the ability to administer inhaled nitric oxide may favor general anesthesia with endotracheal intubation.5 Chosen obstetric delivery method should take into consideration the need to avoid increases in PVR, while optimizing surgical needs and minimizing pain. Successful deliveries and fetal outcomes have been reported, suggesting it is not necessary for these women to avoid or terminate desired pregnancies especially with well-controlled pulmonary disease and acceptable or near normal hemodynamics.
Hemnes AR, Kiely DG, Cockrill BA, et al.
Statement on pregnancy in pulmonary hypertension from the Pulmonary Vascular Research Institute.
Pulm Circ. 2015;5(3):435-465.
Ventetuolo CE, Klinger JR.
Management of acute right ventricular failure in the intensive care unit.
Ann Am Thorac Soc. 2014;11(5): 811-822.
Tsapenko MV, Tsapenko AV, Comfere TB, Mour GK, Mankad SV, Gajic O.
Arterial pulmonary hypertension in noncardiac intensive care unit.
Vasc Health Risk Manag. 2008;4(5):1043-1060.
Olsson KM, Channick R.
Pregnancy in pulmonary arterial hypertension.
Eur Respir Rev. 2016;25(142):431-437.
Han H, Francis JK, Spitzer Y, Reddy S.
Anesthetic management of parturients with pulmonary hypertension undergoing cesarean deliveries.
J Clin Anesth. 2019;57:79.