A 15 year old male presents to the emergency department at 2:15 a.m. after awakening late at night with difficulty breathing.
He initially experienced severe difficulty, but upon arrival in the ED he reported some improvement. He had some mild chest pain. He was not very communicative and declined to describe the chest pain further.
He was brought in by his father who noted he was behaving differently than usual. The patient admitted to smoking crack cocaine on the day prior to arrival. He denied other illicit drug or alcohol use. His father was aware of the substance abuse and attributed his unusual behavior to this.
T36.6, P82, R22, BP 144/84.
His oxygen saturation in room air was 100%. He was awake and alert, although he was noted to exhibit a somewhat flattened affect. He ambulated well. He exhibited a dry cough.
Pertinent physical findings revealed clear lung fields. Auscultation of the heart revealed normal S1 and S2 with what was thought to be a friction rub. This was described as a fine grating sound similar to the dehiscence of Velcro. It was very brief and was noted to occur regularly with each heart beat in systole. There was no chest wall tenderness. His peripheral pulses were good. His color and perfusion were good. The remainder of the exam was unremarkable.
A normal EKG was obtained.
A chest radiograph was obtained to look for evidence of pericarditis.
The patient returned from the imaging department 40 minutes later.
His CXR showed no cardiomegaly. His aortic shadow appeared to be normal.
At this time, his symptoms had spontaneously resolved. He was no longer short of breath. His chest pain had also resolved. His vital signs showed improvement. Cardiac auscultation at this time was normal. The fine grating sound could no longer be heard. The patient was discharged at 3:30 a.m. in good condition with a diagnosis of transient shortness of breath with a history of substance abuse.
He was advised to rest and refrain from further drug use. He was instructed to return if his symptoms worsened.
Radiologist report on CXRs[DDET Read radiology comments]
Later that morning, a radiologist reading his CXR noted a pneumomediastinum. On the PA film, air is seen dissecting along the superior mediastinum bilaterally, and shadows consistent with subcutaneous emphysema were noted apically over the left lung.
Note the vertical air densities extending upward from the mediastinum more noticeable on the left than on the right. There is also air superimposed over the inferior aspect of the aortic arch. More impressively, the lateral radiograph revealed mediastinal air trapping with thymic demarcation.
Note the oblique air space present above (anterior and superior to) the heart.
There are also vertical air densities outlining the trachea.[/DDET]
The patient was called to notify him of the findings. His symptoms had resolved. He was instructed to follow up with his private physician.
Learning points – pneumomiastinum and crack cocaine
- The abuse of crack cocaine has become epidemic among adolescents in many areas. The possibility of drug abuse in any adolescent who arrives with chest or pulmonary complaints should be considered (1).
- Abnormal chest radiographs are quite common in cocaine users admitted with respiratory complaints, ranging from 12-55% (2). Both pneumomediastinum and pneumothorax are relatively common after illicit cocaine use, and the incidence is higher for those who smoke crack cocaine, a relatively pure, extremely addictive, intensely euphoric alkaloid form of cocaine. Of those with pneumomediastinum, one series reported 73% with detectable subcutaneous emphysema and 50% with Hamman’s sign, an unusual systolic crunch heard over the cardiac apex and the left sternal border (3). The mechanism of air leaks is felt to be related to exertional inhalation with Valsalva manoeuvers. Drug users do this to accomplish the highest delivery of drug to the bloodstream. Irritants in the inhalant and the higher temperatures of the inhalant may induce reflex coughing, resulting in even greater intrathoracic pressure surges. In most cases, air is allowed into the mediastinum by spontaneous rupture of distended alveoli into the pulmonary vascular sheath (4).
- The peculiar crackling, bubbling, or churning sounds heard usually during systole (Hamman’s sign) are considered, by some, to be pathognomonic for mediastinal emphysema, and were first described in 1945 by Hamman (5), who also attributed interstitial emphysema to trauma, increased intrapulmonary pressure (Valsalva manoeuvers and cough), or spontaneous rupture of alveoli. Hamman’s sign is often noted to be transient, as in this case. Hamman’s sign has also been well described with isolated pneumothoraces and may represent free pleural air cyclically channeled through a lung fissure (6).
- Retrospective reviews of young children with tracheobronchial foreign body aspiration have revealed a relatively high frequency of pneumomediastinum on initial chest radiographs. The radiographic finding of pneumomediastinum should lead to the consideration of foreign body aspiration in any child in a high risk age group (7,8).
- Pneumomediastinum is seen not uncommonly as a relatively late complication of cystic fibrosis (9), and if noted in any steroid-dependent child with unexplained fevers, oesophageal rupture should be considered (10). Rarely, pneumomediastinum may signal tracheobronchial disruption in any patient with blunt thoracic trauma (11).
- Pneumomediastinum and/or pneumothorax should be considered as an etiology for respiratory complaints or chest pain in any young person whose daily activities may include an unusual frequency of Valsalva manoeuvers or increased intrathoracic pressure. Examples include a young trombonist (12) and a Chinese martial arts expert (13).
- Complete recovery within days is expected for drug- and Valsalva-related pneumomediastinum.
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