Short of Breath Short List

The diagnosis of cardiopulmonary pathology in a pregnant patient presenting with dyspnea and/or chest pain can be an arduous task given the physiologic changes of pregnancy. Pregnancy leads to decreased pulmonary functional reserve and increased oxygen consumption by the placenta, fetus, and maternal organs. Maternal hypoxia may not be well tolerated by a mother or her fetus due to the reduced partial pressure of oxygen in the fetal umbilical vein and decreased oxygen-carrying capacity of women who develop anemia in pregnancy.¹ Additionally, fetal hypoxia is detrimental to fetal development and can actually alter myocardial structure and cause a decline in cardiac performance, among other damaging sequelae.² Thus, dyspnea in pregnancy has the potential to result in negative outcomes, particularly when it is due to an unanticipated or uncommon etiology. The article on page 19 discussed PE, a potentially deadly cause for dyspnea in pregnancy, but here are discussed two more potentially devastating pathologies you don't want to miss.

Case One

A 32-year-old, 36-week pregnant female with a history of intermittent asthma presents with one week of worsening right-sided, pleuritic chest pain and shortness of breath. Albuterol and beclomethasone have provided no relief. A chest x-ray in the ED reveals a large right-sided pneumothorax. An ultrasound-guided chest tube is placed and she is admitted. Three days later her pneumothorax has resolved, and she later goes on to have an uncomplicated vaginal delivery.

Spontaneous pneumothorax in pregnancy is rare, but has been documented in at least 56 published case reports. A review of these cases revealed that the average age of pregnant patients with a pneumothorax was 26.4 years (similar to the age of non-pregnant females with a pneumothorax). In about half of cases, pneumothorax occurred in the first or second trimester, the other half occurring during the perinatal period. The same review showed that risk factors in pregnant patients included a prior pneumothorax (40%), underlying infection (30%), asthma, cocaine use, and hyperemesis gravidarum.³ A pneumothorax may occur due to rupture of small subpleural blebs when alveolar intrathoracic pressure increases, such as during labor.⁴

Treatment of an acute pneumothorax in pregnancy is to be approached similarly to that in a non-pregnant patient. For a small pneumothorax, admission and close observation is an appropriate option. A large pneumothorax, on the other hand, should be treated with tube thoracostomy. It is important to note that total lung volume in pregnancy is decreased due to upward displacement of the diaphragm.⁵ In the second and third trimesters, a thoracostomy tube may need to be inserted higher than would be necessary in a non-pregnant patient, to ensure that it is not inadvertently placed in the trans-hepatic or trans-splenic space. Some experts suggest inserting the tube in the intercostal space between the third and fourth ribs in obstetric patients.⁶ When uncertain, ultrasound can be an extremely useful aide for ensuring safe placement.

Thoracotomy or thoracoscopy (e.g., VATS) may be indicated in cases of recurrent, persistent, or bilateral pneumothorax.² In the case reports mentioned previously, half of the patients ultimately required a thoracotomy for recurrent or persistent pneumothorax. Among the 56 women, obstetric outcomes were generally favorable; 80.8% had vaginal deliveries, 17.3% had cesarean deliveries, and one fetal loss occurred. No other adverse outcomes were reported. In women who have had a pneumothorax, positive pressure ventilation should be avoided during delivery to prevent recurrence. Pneumothorax is not an indication for cesarean section, and these should be performed only for the usual obstetric indications.⁷

Pneumothorax in pregnancy is believed to be underreported, as chest pain and dyspnea are frequently attributed to diagnoses such as paroxysmal tachycardia, neuralgia, physiologic dyspnea of pregnancy, or asthma exacerbation.⁸ If a pregnant patient presents to your ED with these symptoms, a thorough history and physical exam should be performed. Inquire about history of pneumothorax and other risk factors. Physical exam findings may include dyspnea or tachypnea, hypoxia, tachycardia, cyanosis, or unilaterally decreased breath sounds. A chest radiograph with an abdominal shield is required for definitive diagnosis, however, and a shielded CT is not unreasonable if an operative intervention is being considered. Pulmonary ultrasound can also be useful in making the diagnosis. Just as in the non-obstetric patient, prompt, accurate diagnosis is crucial, as sudden death or respiratory collapse can occur without appropriate intervention, and even brief episodes of maternal hypoxia can have devastating effects on a fetus.

You may counsel pregnant patients that smoking cessation and avoiding major changes in ambient pressure such as going to high altitude, skydiving, and flying in unpressurized aircraft are good preventive measures.

Case Two

A 27-year-old female who is three weeks postpartum presents complaining of increasing fatigue and dyspnea with even slight exertion. She has developed a cough, and has recently had several brief episodes of chest pain. Physical examination reveals basilar crackles in the lungs, pedal edema, and a new cardiac murmur. A chest radiograph is obtained and shows pulmonary edema. An echocardiogram shows cardiomegaly and an abnormal left ventricular (LV) systolic function with an ejection fraction (EF) of 35%. She is placed on oxygen, given furosemide, nitroglycerin, and digoxin, and cardiology and obstetrics are consulted. She is admitted for treatment and management of peripartum cardiomyopathy (PPCM).

PPCM is an idiopathic form of dilated cardiomyopathy presenting with heart failure (HF) secondary to LV systolic dysfunction. It occurs towards the end of pregnancy or in the first several months following delivery and diagnostically requires that no other cause of HF be identified.⁹ PPCM is a rare complication of pregnancy that affects approximately 1:3,200 live births in the U.S.,¹⁰ but is a major cause of maternal morbidity with a mortality rate of 2-27%.¹¹

Risk factors are believed to include increased age, high parity, preeclampsia or hypertension of pregnancy, use of tocolytics, twin pregnancy, obesity, and low socioeconomic status. Still, approximately one-third of cases occur in young, primigravid patients.¹² Incidence is significantly higher in developing nations, but in the United States is 16-times higher among African-American women.¹³ The etiology and pathogenesis of PPCM is not well understood. Available studies posit that myocarditis, malnutrition, high sodium intake, viral infections (e.g., EBV and CMV), autoimmunity, genetic predisposition, and/or oxidized prolactin may be contributing factors to the development of this disease process.¹²

Rapid diagnosis and treatment are essential. PPCM is a diagnosis of exclusion, and other causes of cardiomyopathy and heart disease must be ruled out. Presenting signs and symptoms are the same as those of heart failure in non-obstetric patients. Chest radiograph with abdominal shield should be ordered in pregnant patients presenting with dyspnea, tachycardia, or hypoxia, as radiographically-evident pulmonary edema may be present. Patchy infiltrates in the lower lungs fields with vascular cephalization (indicating high pressures), cardiomegaly, and pleural effusions suggest congestive HF. ECG results may be normal, or demonstrate sinus tachycardia, low voltage, left ventricular hypertrophy, non-specific ST-segment and T-wave abnormalities, or, more rarely, atrial fibrillation. A prompt echocardiogram is key for diagnosis of PPCM and should be performed in all women for whom the diagnosis is suspected. In PPCM, the EF is nearly always less than 45%.

Treatment for pregnant women with systolic dysfunction typically consists of supplemental oxygen, digoxin, loop diuretics, vasodilators (hydralazine and nitrates), and beta blockers (carvedilol or metoprolol), all of which may be initiated in the ED depending on how symptomatic the patient is. Anticoagulation with heparin or low molecular weight heparin should be administered for an EF less than 30% to reduce the risk of venous and arterial thrombosis.¹² Consults cardiology and obstetrics are warranted, and in acute cases you should consider admission or transfer to an ICU for continuous maternal and fetal monitoring.

Prognosis is dependent on recovery of ventricular function. Studies have shown that half of patients show significant improvement with regard to symptoms and ventricular function within six months, and one-third return to baseline cardiac function in that time.¹⁴ Causes of death in patients with PPCM include progressive heart failure, arrhythmia, or thromboembolism. Women with low EFs in pregnancy are at high risk of developing worsening cardiac function and developing HF in subsequent pregnancies,^15,16 making perinatal counseling imperative for these patients.

Conclusion

Causes of dyspnea and chest pain in pregnancy include, but are not limited to, pulmonary embolism, amniotic fluid embolism, noncardiogenic or cardiogenic pulmonary edema, myocardial infarction, pneumonia, asthma exacerbation, aortic dissection, and preeclampsia. Be sure to get a detailed past medical and obstetric history from pregnant patients with concerning symptoms and perform a thorough physical exam so these diagnoses are not missed. Don't be afraid of using appropriate radiographic studies when indicated. A healthy fetus requires a healthy mother, and our pregnant patients are a special population that deserve the best care we have to offer.

References

1. Rajiv Garg, Sanjay et al. Spontaneous pneumothorax: An unusual complication of pregnancy“ A case report and review of literature. Annals of Thoracic Medicine. 2008 Jul-Sep; 3(3): 104-105.
2. Patterson, AJ and Zhang, L. Hypoxia and fetal heart development. Curr Mol Med. Oct 2010; 10(7): 653“666.
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4. Burrow GN, Duffy TP, eds. Medical complications during pregnancy. 5th  ed. Philadelphia: W.B. Saunders, 1999:390.
5. Stewart, Charles J.  €œThe diaphragm in pregnancy.  Tubercle 32.2 (1951): 40-43.
6. Jara-Almonte, Geoff and Fairbrother, Hilary. Resuscitation of the pregnant trauma patient: pearls and pitfalls. Feb 6, 2015. EMDocs website accessed at http://www.emdocs.net/resuscitation-of-the-pregnant-trauma-patient-pearls-pitfalls/ on 4/26/15.
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9. Sliwa K, Hilfiker-Kleiner D, Petrie MC, et al. Current state of knowledge on aetiology, diagnosis, management, and therapy of peripartum cardiomyopathy: a position statement from the Heart Failure Association of the European Society of Cardiology Working Group on peripartum cardiomyopathy. Eur J Heart Fail. 2010;12(8):767-78.
10. Mielniczuk LM, Williams K et al. Frequency of peripartum cardiomyopathy. Am J Cardiol. 2006;97:1765-8.
11. Cooper LT, Mather PJ et al. Myocardial Recovery in Peripartum Cardiomyopathy: Prospective Comparison with Recent Onset Cardiomyopathy in Men and Nonperipartum Women. Journal of Cardiac Failure. 2012;18:28-33.
12. Karaye KM and Henein MY. Peripartum cardiomyopathy: a review article. International Journal of Cardiology. 2013: 164:33-38.
13. Gentry MB, Dias JK, et al. African-American Women Have a Higher Risk for Developing Peripartum Cardiomyopathy. J Am Coll Cardiol. Feb 16, 2010;55(7):654-659.
14. Michael P. Carson. Peripartum Cardiomyopathy. Medscape. Updated Oct 6, 2014. Accessed at http://emedicine.medscape.com/article/153153-overview on 3/25/15.
15. Felt JD, Christie LG, Murphy JG. Brief communication: Outcomes of subsequent pregnancy after peripartum cardiomyopathy: a case series from Haiti. Ann Intern Med. July 4, 2006;145(1):30-4.
16. 16.   Felt JD, Fristoe KL, Welsh SN. Risk of heart failure relapse in subsequent pregnancy among peripartum cardiomyopathy mothers. Int J Gynaecol Obstet. Nov 28, 2009.