Cardiac instability due to Pneumomediastinum during second stage of labour

Rafi J, *Muppala H, Schaefer B

Women’s Health Directorate, North Manchester General Hospital, Delaunays Road, Crumpsall, Manchester, M8 5RB, UK

*Corresponding author

Women’s Health Directorate, Ysbyty Gwynedd, Penrhosgarnedd, Bangor, Gwynedd, LL57 2PW, U.K.

Email: drmuppala@dochdoc.com

SMJ 2009 54(2): 58

Abstract:

This case reports spontaneous pneumomediastinum in the second stage of labour leading to cardiovascular instability. Forceps were used to expedite delivery. Examination revealed characteristic crepitus of subcutaneous emphysema in the neck region, which was confirmed on chest X-Ray and CT scan. The patient was managed in the high dependency unit (HDU) for 48 hours and made a full recovery.

Key words:

Hamman’s syndrome, Intrapartum, Pneumomediastinum, Subcutaneous emphysema

 

Case report:

An 18-year-old primigravida was admitted to hospital in established labour at 40 weeks of gestation. She had an uneventful antenatal period with no significant past medical or surgical history. Her personal history revealed she smoked 5 cigarettes a day with cannabis. The first stage of labour lasted for 15 hours and she received epidural analgesia. Labour was augmented with oxytocin. After thirty minutes into the active second stage, the patient began to complain sudden sharp central chest pain. Her pulse rate was 147/min, normal blood pressure and O2 saturations were normal at 99% in air. The epidural was topped up and forceps were used to expedite delivery. The second stage lasted for one hour. She delivered a healthy male baby weighing 3742 grams. The APGAR scores were 8 and 9 at 1 and 5 minutes respectively. The severity of chest pain decreased over the next 30 minutes. An ECG was requested, which showed sinus tachycardia of 150/min.

 

One hour post-delivery, her vital signs suddenly become unstable with blood pressure at 79/35 mmHg and pulse rate rising to 180/min with normal O2 saturations. An anaesthetist and medical team were requested to attend for resuscitation on the suspicion of supraventricular tachycardia. The patients blood pressure was stabilised with intravenous fluids. Arterial blood gases were normal.

 

She had no respiratory symptoms. Examination revealed characteristic crepitus of subcutaneous emphysema in the neck region; with centrally placed trachea and bilateral equal entry of breath sounds. The cardiothoracic team were contacted in view of the strong possibility of pneumomediastinum compressing on major blood vessels and leading to decreased cardiac output. Subcutaneous emphysema with pneumomediastinum was seen on chest X-Ray [Fig 1]. A CT scan was performed for confirmation of pneumomediastinum, which also ruled out pneumopericardium [Fig 2]. In view of the cardiovascular instability, the patient was transferred to HDU for monitoring. With input from the multi-disciplinary team, the patient recuperated uneventfully and was discharged home on fourth day. At an outpatient follow-up three weeks later, a chest X-Ray and review by a respiratory physician confirmed full recovery from this potentially life-threatening condition.

 

Fig 1. Immediate postnatal Chest X-ray. Picture indicating subcutaneous emphysema and air in the mediastinum. Lungs appear unremarkable. 

 

Fig 2. Postnatal CT scan of thorax with contrast. Confirming subcutaneous emphysema and the pneumomediastinum

 

Discussion:

Pneumomediastinum in labour, also known as Hamman’s Syndrome, was first reported 400 years ago. This rare condition has an estimated incidence between 1:2,000 and 1:100,000. Only 200 cases have been reported so far in the literature.1,2

 

Subcutaneous emphysema and pneumomediastinum occurs mostly in the second stage of labour in healthy primiparous women with prolonged labour and big babies.1 It is thought that the condition involves the escape of air from the ruptured alveoli secondary to valsalval manoeuvre in the active second stage of labour. The air then enters into the sheaths of the pulmonary vessels to mediastinum and subsequently tracks through the fascial planes into subcutaneous tissues. In our case, it is speculated that the patient’s use of cannabis could have been associated with pneumomediastinum, as there are increasing reports of its detrimental effects on the respiratory tract.3

 

Differential diagnoses includes pulmonary thromboembolism, amniotic fluid embolism, oesophageal rupture, myocardial infarction and lastly dissecting aortic aneurysm.1 In our case a rupture in the oesophagus causing air in the mediastinum, could not be ruled out. As such, broad-spectrum antibiotic cover with Augmentin was used along with oral analgesia. We considered pulmonary embolism and myocardial infarction in the initial workup but did not initiate antithrombotic treatment.4 This was because our patient did not have respiratory symptoms, her oxygen saturations were maintained within the normal range and her chest pain improved over 30 minutes before her vitals deteriorated.

 

The most important clinical feature is palpable crepitations on face and neck, which is due to subcutaneous emphysema. Other features described are tachycardia, fever and loss of cardiac dullness, decreased heart sounds or crunching sounds over precordium on auscultation synchronous with cardiac cycle.1 It is essential that pneumomediastinum is recognised and treated promptly, as there are life-threatening complications such as pneumothorax, cardiac compression and decreased blood flow to and from the heart, leading to cardiac failure.2,5 A simple chest X-ray will confirm the diagnosis and preclude other invasive tests and inappropriate treatment. Although it follows self-limiting course, once suspected, it is important to avoid inhalational analgesia, to shorten the active second stage of labour and involve physicians to avoid potential complications. The occurrence of cardiovascular instability amongst patients with pneumomediastinum in labour or postpartum, is reported rarely in the literature and hence the importance of our case. A literature search (using Pubmed) revealed no cases of cardiovascular instability due to pneuomediastinum in the second stage of labour. It is important to consider invasive and aggressive management if evidence of cardiovascular instability develops due to potential for increased morbidity and mortality. Patients should be counselled that there is no increased risk of recurrence in the subsequent pregnancies.5,6 

 

In conclusion, our case of spontaneous pneumomediastinum in the second stage of labour leading to cardiovascular instability was appropriately managed with multidisciplinary input in the HDU. The possibility of pneumomediastinum should be considered in the differential diagnosis in women presenting with chest pain in the active second stage of the labour. 

 

References:

  1. Balkan ME, Alver G. 2006. Spontaneous Pneumomediastinum in 3rd trimester of pregnancy. Ann Thorac Cardiovasc Surg 12(5):362-4.

  2. Norzilawati MN, Shuhalia A, Rashid ZMR. 2007. Postpartum pneumomediastinum. Singapore Med J 48(6):174-6.

  3. Feldman AL, Sullivan JT, Passero MA, Lewis DC. 1993. Pneumothorax in polysubstance abusing marijuana and tobacco smokers: three cases. J Subst Abuse 5:183-6.

  4. Nieboer B, Aboosy N, Verschoor L, Huisman A. 2006. Pneumomediastinum as a cause of acute chest pain postpartum. J Matern Fetal Neonatal Med 19(4):243-5.

  5. Miguil M, Chekairi A. 2004. Pneumomediastinum and pneumothorax associated with labour. Int J Obstet Anesth 13(2):117-9.

  6. Bonin MM. 2006. Hammn’s syndrome (spontaneous pneumomediastinum) in a parturient: a case report. J Obstet Gynaecol Can 28(2):128-31.

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