Hashim, Taimoor MD, MB.BS; Chaudry, Ayesha H. MB.BS; Ahmad, Khurram MD; Imhoff, Jennifer PA-C; Khouzam, Rami MD, FACC, FACP, FASNC, FASE, FSCAI
A 22-year-old man with history of asthma presented to the ED with chest and neck pain as well as shortness of breath for the past 4 hours. He was in his usual state of health until he suffered an asthma attack at work after being exposed to old insulation material. The violent bout of coughing and wheezing lasted at least 30 minutes, and he had to use an albuterol inhaler several times before symptoms subsided. Shortly thereafter, he developed severe chest and neck pain, profound neck swelling, difficulty swallowing, and hoarseness.
On presentation to the ED his vital signs were heart rate, 120 beats/minute; respirations, 28; temperature, 97.6° F (36.4° C); and SpO2, 92% on room air. He was in moderate distress secondary to the chest pain, which was described as sharp, 8 in intensity (on a pain intensity rating scale of 0 to 10), and pleuritic in nature. He could hardly talk in short phrases.
Physical exam The physical exam was positive for obvious fullness and swelling of the root of his neck on both sides. Crepitation could be heard on palpation of the neck, anterior chest wall, and both axillae. The examination of the oropharynx did not show any signs of compromise. He did not have stridor, but bilateral wheezing was noted on lung examination, with hyperresonance to percussion. The trachea was central on palpation. The cardiac examination was positive for Hamman sign (crunching sound heard over the apex during systole), and heart sounds were distant.
The rest of his examination, including abdominal and extremity examination, was within normal limits. Laboratory data, which included complete blood cell count, basic metabolic profile, and cardiac biomarkers, were all within normal limits. An ECG showed sinus tachycardia with right axis deviation. Chest radiograph (posteroanterior view, Figure 1) and computed tomography (CT) scan of the chest without contrast (Figure 2) confirmed the diagnosis of pneumomediastinum, with subcutaneous emphysema extending into the neck muscles (Figure 3).
Initial treatment Due to the severity of his pain, the patient received 2 mg of IV morphine followed immediately by 30 mg of IV ketorolac, which reduced his pain level to 4. He then received albuterol and ipratropium bromide nebulizer inhalation treatments along with 100% supplemental oxygen via a non-rebreather face mask; IV methylprednisolone; and 1 dose of 0.1 mg subcutaneous epinephrine (1:1,000).
These treatments stabilized his condition and he was admitted to the telemetry unit for observation. His breathing and neck swelling continued to improve so that he was able to swallow and was slowly weaned off the supplemental oxygen. His pain also improved and he was transitioned to oral nonopioid analgesics. He was discharged the next day with instructions to avoid lifting heavy objects for the next 2 to 3 weeks.
His follow-up chest radiograph 4 weeks later showed complete resolution of the pneumomediastinum.
Spontaneous pneumomediastinum is a rare complication of asthma exacerbation. The exact incidence is unknown; however, Newcomb and Clarke, as well as Abolnik and colleagues reported it to be around 1 in 30,000.1-3 A lower incidence of 1 in every 42,000 admissions was reported by Brody and colleagues.4 A somewhat higher incidence has been reported in other studies involving healthy young individuals in US military hospitals.5,6
Spontaneous pneumomediastinum also has been reported after patient use of recreational drugs such as marijuana, heroin, free-based cocaine, crack cocaine, and ecstasy.7-11 Other precipitating factors include asthma exacerbation, diabetic ketoacidosis, straining during exercise, and violent coughing or emesis.6,12-14 Rarely, spontaneous pneumomediastinum can occur during an upper respiratory tract infection.3 The condition also can occur during parturition, or in the postpartum period.15,16
The pathophysiology involves a sudden increase in intrathoracic pressure, which can occur during episodes of coughing, straining, intense vomiting, and even strenuous crying in patients with a predisposing condition such as asthma or chronic obstructive pulmonary disease.17 The intense increase in intrathoracic pressure is transmitted to the alveoli, which rupture, letting air leak into the interstitium. Due to the negative pressure in the interstitial space, air easily dissects its way to the hilum, then to the mediastinum, and often to the neck and subcutaneous tissue.18 Spontaneous pneumomediastinum usually has a benign course, but rarely it can be complicated by tension pneumomediastinum, also called malignant pneumomediastinum. When this happens, patients show signs of respiratory and/or circulatory distress in addition to chest pain. Treatment usually involves placing the patient on 100% oxygen, which increases the diffusion pressure of nitrogen in the interstitial tissue and promotes rapid absorption.18 If this fails to resorb the air from the mediastinum, surgical decompression is done by incisions in the supraclavicular fossa posterior to the sternocleidomastoid muscle and in the suprasternal notch.18 In severe cases, tracheostomy may be needed.19
Similarly, pneumothorax during an asthma attack can present with chest pain and shortness of breath with increased hyperresonance on the ipsilateral side in the case of tension pneumothorax with tracheal deviation and hemodynamic instability. The increased hyperresonance may be difficult to appreciate due to global air trapping during an acute asthma attack.
Chest tube placement is indicated to treat tension pneumothorax (which is a medical emergency) and for a simple pneumothorax, defined as 20% or greater of the volume of the hemithorax.20 Sometimes tracheostomy is done for persistent bronchospasm.19
A patient with spontaneous pneumomediastinum typically has chest pain (66.6% to 88% of cases), dyspnea (25%-100%), cough (41.6%), sore throat (25%), dysphagia (8.3% to 40%), neck swelling (4%), or neck pain.3,21-25 The two most commonly found signs are subcutaneous emphysema and Hamman sign, which are present in up to 88% of reported cases.24 The most specific sign is subcutaneous emphysema, which has a positive predictive value of 100%.26 In our patient, the most impressive presentation was the neck swelling, which not only caused difficulty breathing, swallowing, and hoarseness of voice, but also raised a concern for possible impending airway compromise. The patient did not start showing signs of improvement until he had received aggressive bronchodilator nebulizer treatments, 100% supplemental oxygen, IV steroids, and a dose of subcutaneous epinephrine. Our explanation for this is that the bronchodilators, steroids, and epinephrine caused rapid reversal of the inflammatory process in the bronchioles, leading to decreased air trapping and intra-alveolar pressure and preventing further air leak into the mediastinum and subcutaneous tissue.
At the same time, adequate pain control is very important. In our case, IV morphine helped the patient not only with pain control but also with relaxation and slower breathing. Similarly, the use of IV ketorolac helped with analgesia and decreased the inflammatory process. The 100% oxygen helped in rapid reabsorption of air from subcutaneous tissue.
A routine posteroanterior chest radiograph can establish the diagnosis; however, in about 50% of cases, the diagnosis can be missed, and for this reason a lateral chest radiograph is more sensitive in making the diagnosis of spontaneous pneumomediastinum.27,28 In the differential diagnosis, also consider other secondary life-threatening causes of spontaneous pneumomediastinum, such as tracheobronchial injury, esophageal perforation, and retropharyngeal abscess, and rule these out via appropriate imaging studies such as bronchoscopy, esophagogram (using nonionic contrast), or CT scan of neck and soft tissues.27
Very rarely, spontaneous pneumomediastinum can be a recurrent phenomenon after athletic activity, during diabetic ketoacidosis, and after cyclical vomiting.22,29,30
Treatment is conservative for the most part, and consists of managing asthma symptoms, controlling pain, and administering supplemental oxygen. The evidence to support prophylactic antibiotics is not entirely conclusive.21 Some experts recommend hospitalization for all cases for at least 24-hour observation.1 Others recommend a less-aggressive and more individualized approach.21 In our opinion, the prudent course is to individualize the management strategy and admit patients as critical as our patient for observation, while allowing more stable patients with good follow-up to be discharged from the ED.
Spontaneous pneumomediastinum is a known complication of asthma usually seen in young men during an asthma attack. The most common presenting symptoms are chest pain, dyspnea, and neck pain; subcutaneous emphysema and Hamman sign are seen in a vast majority of cases. Although spontaneous pneumomediastinum usually is benign, recognizing it promptly is important because of the small but present risk of progression to a life-threatening condition.
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