Spontaneous pneumomediastinum associated with orthognathic surgery A case report Joseph F. Piecuch, D.M.D., UNIVERSITY
M.D., crnd Roger A. West, D.M.D.,
Seattle, Wush,
OF WASHINGTON
Numerous articles identifying pneumomediastinum as an immediate complication of dental and oral surgical procedures have been published. A patient who developed a spontaneous pneumomediastinum as a delayed complication, apparently not directly related to the surgical procedure, is presented in this report.
T
here are four etiologic mechanisms for the production of a pneumomediastinum, including dissection of air from above through cervical fascial planes, dissection from the adjacent pulmonary parenchyma, dissection from below through fascial planes continuous with the retroperitoneum, and direct penetrating wounds of the th0rax.j This should be differentiated from spontaneous pneumomediastinum, which has been defined as a direct dissection of air from the pulmonary parenchyma without apparent cause. There are reports in the literature of pneumomediastinum occurring in association with dental and oral surgical procedures. *. g, “-I7 In all these instances the apparent mechanism has been dissection of air through cervical fascial planes to the mediastinum, such as following repair of facial fractures, antral irrigation, extractions, and the use of high-speed dental engines. This article reports an unusual instance in which spontaneous pneumomediastinum occurred 2 days following orthognathic surgery. Clinical circumstances surrounding the patient are presented and an approach to diagnosis and management is discussed. CASE REPORT
A 24-year-old man presented for surgical correction of maxillary hyperplasia and mandibular hypoplasia. Presurgical orthodontic treatment had been completed, and a combination of maxillary and mandibular osteotomies with bone grafting from the left iliac crest to the maxilla was planned. Review of the patient’s past medical history revealed that he had mild asthma as a young child but had been without symptoms for 10 years. His surgical procedure had been postponed 1% weeks because of mild flu, but he was fully recovered at the time of surgery. Physical examination and
506
preoperative laboratory studies, including chest radiographs, were unremarkable. On February 10, a total maxillary alveolar osteotomy for intrusion and expansion and a bone graft from the iliac crest to the maxilla were performed in conjunction with bilateral mandibular sagittal osteotomies. No difficulties were experienced at the time of surgery, and the initial postoperative course was uneventful. On February 12, at 1 PM, the patient reported a slight pain in his left anterior chest which did not change with position. The pain remained unchanged until about 4 PM, at which time he experienced a sharp, nonradiating substemal pain. Again there was no change in intensity of the pain with change in posture, and the patient denied dyspnea. The patient’s body temperature was 37.8” C (rectal), blood pressure 130/70, respirations 20, and pulse 84. He had the anticipated degree of postoperative facial edema, and there was no crepitus. Both lungs were clear to auscultation, with breath sounds full bilaterally, and percussion showed that both diaphragms moved well. A loud, nonradiating grade IV/VI rub was heard best at the left parastemal and substemal regions. It was louder in systole. The heart sounds were normal but muffled. No murmurs were present. Jugular veins and carotid and peripheral pulses were all normal. Laboratory studies at that time included a hematocrit of 40, a white blood count of 17,200 with a predominance of polymorphs, and arterial blood gas concentrations on room air of pH 7.43; PO,, 93; pCOz, 39; and calculated bicarbonate, 26. The electrocardiogram was within normal limits. Chest radiographs revealed clear lung fields. However, a double density was present in the cardiac outline. This air shadow appeared to include the great vessels (Fig. 1). The diagnosis of pneumomediastinum, suspected from the symptoms and physical examination, was confirmed by the radiograph. Initially, the Division of Cardiac Surgery was alerted to the problem so that emergency decompression could be accom0030-4220/79/120506+03$00.30/0
0
1979 The C. V. Mosby CO.
Spontaneous pneumomediastinum
Volume 48 Number 6
Fig. 1. PA chest radiograph
phshed with a minimum of delay if the need arose. Following this, a search was made for any possible etiologic factor. A Hypaque swallow was performed under fluoroscopy, revealing good esophageal motility without evidence of extravasation. Bronchoscopy was carried out via an awake nasal approach without release of intermaxillary fixation, revealing no lesions of the larynx, trachea, or main stem bronchi. No specific etiologic factor was found. The patient remained in the hospital for observation for 4 days, and his symptoms, as well as the rub, gradually decreased over that time. Chest x-rays showed minimal regressive changes at the time of discharge on February 16. At the time of this writing, over 2 years have passed with no untoward sequelae. DISCUSSION
Spontaneous pneumomediastinum may occur secondary to rupture of alveoli, generally those situated along the margins of lung parenchyma near the mediastinum or along the wall of a blood vessel. Air can then pass through the interstitial tissues directly to the periphery, or along the great vessels. Increased intrapulmonary pressure has been considered a possible etiologic mechanism of alveolar rupture. Factors involved in the production of increased intrapulmonary pressure are many. Examples include foreign body occlusion of the trachea and/or bronchi, positive pressure during anesthesia, and straining against a closed glottis, as in heavy exercise or in childbirth.” Coughing or wheezing spasms in asthma, bronchitis, pertussis, and
507
Fig. 2. Lateral chest radiograph.
pneumonia have also been implicated.” Occasionally an alveolus may rupture in a healthy person, without apparent cause, while at rest. This is more common in young men.” Signs and symptoms of pneumomediastinum may be variable, but pleuritic substernal pain is the most constant. The pain may be exacerbated by swallowing. Subcutaneous emphysema (cervical or thoracic) is common. A loud grating precordial sound, the classic ‘ ‘Hamman ‘s crunch, ” is positive in 50 percent of cases and is associated with systole. It may also be heard in pneumothorax, which may be an associated condition. Fever is generally absent. Symptoms of cardiac tamponade, including dyspnea, tachycardia, decreased blood pressure, and increased jugular venous distention, may be present to a variable degree, depending on the severity of the condition.s-X Chest radiographs are of great value in arriving at the diagnosis.‘O The displacement of the mediastinal pleura from the heart border is particularly well seen on the left in the PA projection (Fig. 1). In this instance an air shadow was noted outlining the aortic arch on the lateral projection (Fig. 2). This air will not shift with a change in body position. Electrocardiogram changes will not be prominent, although nonspecific ST changes, inverted T waves, decreased voltage, or axis shift may occur in up to 25 percent of patients. A leukocytosis is generally absent unless related to organ perforation.fi
508 Piecuch and West Prognosis depends on the amount of air present and the etiology. A phenomenon termed “air block” is especially dangerous in children, in whom the air will not escape via the cervical fascia, possibly because of the presence of a large thymus. Treatment is aimed at removing the cause of the leak if it is apparent; otherwise, close observation is warranted. In severe cases, surgical decompression of the pneumomediastinum is needed. In this patient no cause was found, using a standard investigative approach, so the patient was monitored closely until time of discharge. Several possibilities were explored. Trauma to the esophagus, pharynx, larynx, and tracheobronchial tree were ruled out by fluoroscopy and direct bronchoscopy. Air insufflation secondary to operative wounds was considered but doubted, since there were no immediate postoperative symptoms and cervical emphysema was absent. Positive pressure was a possible cause because the patient had been on a respirator during surgery. However, this was unlikely, as the onset of symptoms was not immediate. The most probable cause was a spontaneous rupture of an alveolus without any increase in intrapulmonary pressure. The slow, gradual onset of pain is unusual. Nevertheless, Hamman ‘3 8 has described some cases in which pain was initially felt lateral to the sternum, later migrating substernally. He postulated that it might represent rupture of an intrapulmonary bleb with dissection through the pulmonary parenchyma. This hypothesis fits the symptoms of this patient. SUMMARY
Pneumomediastinum is a rare complication of head and neck surgery. Nevertheless, when it occurs, it is usually considered to result from direct dissection of air at the time of injury or of surgery. Consequently, it is thought to occur as an immediate complication. This case report suggests that spontaneous pneumomediastinum should not be overlooked in the differential diagnosis of chest pain occurring several days following surgery.
Oral Surg. December, 1979 REFERENCES 1. Adwers, J. E., Hodgson, P. E., and Lynch, R.: Spontaneous Pneumomediastinum, J. Trauma 14: 414-418, 1974. 2. Andsberg, V., and Axell, T.: Mediastinal Emphysema as a Complication of Dental Treatment, Gdontol. Revg. 23: 21-26, 1972. 3. Biennan, C. W.: Pneumomediastinum and Pneumothorax Complicating Asthma in Children, Am. J. Dis. Child. 114: 42-50, 1967. 4. Chiles, D. G.: Pneumothorax, Pneumomediastinum, and Massive Subcutaneous Emphysema After a General Anesthetic, J. Oral Surg. 28: 845-47, 1970. 5. Fraser, R. G., and Pare, J. A. P.: Diagnosis of Diseases of the Chest, vol II, Philadelphia, 1970, W. G. Saunders Co.. pp. 1174-1179. 6. Gray, J. M., and Hanson, G. C.: Mediastinal Emphysema: Aetiology, Diagnosis, and Treatment, Thorax 21: 325-332, 1966. 7. Hamman, L.: Spontaneous Mediastinal Emphysema, Bull. John Hopkins Hosp. 64: l-21, 1939. 8. Hamman, L.: Mediastinal Emphysema, J. Am. Med. Assoc. 128: l-6, 1945. 9. Hunt, R. B., and Sahler, 0. D.: Mediastinal Emphysema Produced by Air Turbine Dental Drills, 3. Am. Med. Assoc. 205: 241-42, 1968. 10. Lillard, R. L., and Allen, R. P.: The Extrapleural Air Sign in Pneumomediastinum, Radiology 85: 1093-98, 1965. 11 Lloyd, R. E.: Surgical Emphysema as a Complication in Endodontics, Dent. J. 138: 393-394, 1975. 12 Meyerhoff, W. L., et al.: Mediastinal Emphysema After Oral Surgery, J. Oral Surg. 83: 477-79, 1973. 13 Noble, W. H.: Mediastinal Emphysema Resulting from Extraction of an Impacted Mandibular Third Molar, J. Am. Dental Assoc. 84: 368-70, 1972. I4 Sandler, C. M., et al.: Pneumoperitoneum, Pneumomediastinum, and Pneumopericardium Following Dental Extraction, Radiology 115: 539-40, 1975. 15 Schwartz, S. I., et al.: Principles of Surgery, ed. 2, New York, 1974, McGraw-Hill Book Co., Inc., p. 660. 16 Switzer, P., Pitman, R. G., and Fleming, J. P.: Pneumomediastinum Associated with Zygomatico-Maxillary Fracture, J. Cana. Assoc. Radiol. 25: 316-318, 1974. 17. Trummer, M. J., and Fosburg, R. G.: Mediastinal Emphysema Following Use of High-Speed Air Turbine Dental Drill, Ann. Thor. Surg. 9: 78-81, 1970. Reprint requests to: Dr. Joseph F. Piecuch Department of Oral & Maxillofacial Surgery Room L-7094 University of Connecticut Health Center School of Dental Medicine Farmington, Corm. 06032
M.D., crnd Roger A. West, D.M.D.,
Seattle, Wush,
OF WASHINGTON
Numerous articles identifying pneumomediastinum as an immediate complication of dental and oral surgical procedures have been published. A patient who developed a spontaneous pneumomediastinum as a delayed complication, apparently not directly related to the surgical procedure, is presented in this report.
T
here are four etiologic mechanisms for the production of a pneumomediastinum, including dissection of air from above through cervical fascial planes, dissection from the adjacent pulmonary parenchyma, dissection from below through fascial planes continuous with the retroperitoneum, and direct penetrating wounds of the th0rax.j This should be differentiated from spontaneous pneumomediastinum, which has been defined as a direct dissection of air from the pulmonary parenchyma without apparent cause. There are reports in the literature of pneumomediastinum occurring in association with dental and oral surgical procedures. *. g, “-I7 In all these instances the apparent mechanism has been dissection of air through cervical fascial planes to the mediastinum, such as following repair of facial fractures, antral irrigation, extractions, and the use of high-speed dental engines. This article reports an unusual instance in which spontaneous pneumomediastinum occurred 2 days following orthognathic surgery. Clinical circumstances surrounding the patient are presented and an approach to diagnosis and management is discussed. CASE REPORT
A 24-year-old man presented for surgical correction of maxillary hyperplasia and mandibular hypoplasia. Presurgical orthodontic treatment had been completed, and a combination of maxillary and mandibular osteotomies with bone grafting from the left iliac crest to the maxilla was planned. Review of the patient’s past medical history revealed that he had mild asthma as a young child but had been without symptoms for 10 years. His surgical procedure had been postponed 1% weeks because of mild flu, but he was fully recovered at the time of surgery. Physical examination and
506
preoperative laboratory studies, including chest radiographs, were unremarkable. On February 10, a total maxillary alveolar osteotomy for intrusion and expansion and a bone graft from the iliac crest to the maxilla were performed in conjunction with bilateral mandibular sagittal osteotomies. No difficulties were experienced at the time of surgery, and the initial postoperative course was uneventful. On February 12, at 1 PM, the patient reported a slight pain in his left anterior chest which did not change with position. The pain remained unchanged until about 4 PM, at which time he experienced a sharp, nonradiating substemal pain. Again there was no change in intensity of the pain with change in posture, and the patient denied dyspnea. The patient’s body temperature was 37.8” C (rectal), blood pressure 130/70, respirations 20, and pulse 84. He had the anticipated degree of postoperative facial edema, and there was no crepitus. Both lungs were clear to auscultation, with breath sounds full bilaterally, and percussion showed that both diaphragms moved well. A loud, nonradiating grade IV/VI rub was heard best at the left parastemal and substemal regions. It was louder in systole. The heart sounds were normal but muffled. No murmurs were present. Jugular veins and carotid and peripheral pulses were all normal. Laboratory studies at that time included a hematocrit of 40, a white blood count of 17,200 with a predominance of polymorphs, and arterial blood gas concentrations on room air of pH 7.43; PO,, 93; pCOz, 39; and calculated bicarbonate, 26. The electrocardiogram was within normal limits. Chest radiographs revealed clear lung fields. However, a double density was present in the cardiac outline. This air shadow appeared to include the great vessels (Fig. 1). The diagnosis of pneumomediastinum, suspected from the symptoms and physical examination, was confirmed by the radiograph. Initially, the Division of Cardiac Surgery was alerted to the problem so that emergency decompression could be accom0030-4220/79/120506+03$00.30/0
0
1979 The C. V. Mosby CO.
Spontaneous pneumomediastinum
Volume 48 Number 6
Fig. 1. PA chest radiograph
phshed with a minimum of delay if the need arose. Following this, a search was made for any possible etiologic factor. A Hypaque swallow was performed under fluoroscopy, revealing good esophageal motility without evidence of extravasation. Bronchoscopy was carried out via an awake nasal approach without release of intermaxillary fixation, revealing no lesions of the larynx, trachea, or main stem bronchi. No specific etiologic factor was found. The patient remained in the hospital for observation for 4 days, and his symptoms, as well as the rub, gradually decreased over that time. Chest x-rays showed minimal regressive changes at the time of discharge on February 16. At the time of this writing, over 2 years have passed with no untoward sequelae. DISCUSSION
Spontaneous pneumomediastinum may occur secondary to rupture of alveoli, generally those situated along the margins of lung parenchyma near the mediastinum or along the wall of a blood vessel. Air can then pass through the interstitial tissues directly to the periphery, or along the great vessels. Increased intrapulmonary pressure has been considered a possible etiologic mechanism of alveolar rupture. Factors involved in the production of increased intrapulmonary pressure are many. Examples include foreign body occlusion of the trachea and/or bronchi, positive pressure during anesthesia, and straining against a closed glottis, as in heavy exercise or in childbirth.” Coughing or wheezing spasms in asthma, bronchitis, pertussis, and
507
Fig. 2. Lateral chest radiograph.
pneumonia have also been implicated.” Occasionally an alveolus may rupture in a healthy person, without apparent cause, while at rest. This is more common in young men.” Signs and symptoms of pneumomediastinum may be variable, but pleuritic substernal pain is the most constant. The pain may be exacerbated by swallowing. Subcutaneous emphysema (cervical or thoracic) is common. A loud grating precordial sound, the classic ‘ ‘Hamman ‘s crunch, ” is positive in 50 percent of cases and is associated with systole. It may also be heard in pneumothorax, which may be an associated condition. Fever is generally absent. Symptoms of cardiac tamponade, including dyspnea, tachycardia, decreased blood pressure, and increased jugular venous distention, may be present to a variable degree, depending on the severity of the condition.s-X Chest radiographs are of great value in arriving at the diagnosis.‘O The displacement of the mediastinal pleura from the heart border is particularly well seen on the left in the PA projection (Fig. 1). In this instance an air shadow was noted outlining the aortic arch on the lateral projection (Fig. 2). This air will not shift with a change in body position. Electrocardiogram changes will not be prominent, although nonspecific ST changes, inverted T waves, decreased voltage, or axis shift may occur in up to 25 percent of patients. A leukocytosis is generally absent unless related to organ perforation.fi
508 Piecuch and West Prognosis depends on the amount of air present and the etiology. A phenomenon termed “air block” is especially dangerous in children, in whom the air will not escape via the cervical fascia, possibly because of the presence of a large thymus. Treatment is aimed at removing the cause of the leak if it is apparent; otherwise, close observation is warranted. In severe cases, surgical decompression of the pneumomediastinum is needed. In this patient no cause was found, using a standard investigative approach, so the patient was monitored closely until time of discharge. Several possibilities were explored. Trauma to the esophagus, pharynx, larynx, and tracheobronchial tree were ruled out by fluoroscopy and direct bronchoscopy. Air insufflation secondary to operative wounds was considered but doubted, since there were no immediate postoperative symptoms and cervical emphysema was absent. Positive pressure was a possible cause because the patient had been on a respirator during surgery. However, this was unlikely, as the onset of symptoms was not immediate. The most probable cause was a spontaneous rupture of an alveolus without any increase in intrapulmonary pressure. The slow, gradual onset of pain is unusual. Nevertheless, Hamman ‘3 8 has described some cases in which pain was initially felt lateral to the sternum, later migrating substernally. He postulated that it might represent rupture of an intrapulmonary bleb with dissection through the pulmonary parenchyma. This hypothesis fits the symptoms of this patient. SUMMARY
Pneumomediastinum is a rare complication of head and neck surgery. Nevertheless, when it occurs, it is usually considered to result from direct dissection of air at the time of injury or of surgery. Consequently, it is thought to occur as an immediate complication. This case report suggests that spontaneous pneumomediastinum should not be overlooked in the differential diagnosis of chest pain occurring several days following surgery.
Oral Surg. December, 1979 REFERENCES 1. Adwers, J. E., Hodgson, P. E., and Lynch, R.: Spontaneous Pneumomediastinum, J. Trauma 14: 414-418, 1974. 2. Andsberg, V., and Axell, T.: Mediastinal Emphysema as a Complication of Dental Treatment, Gdontol. Revg. 23: 21-26, 1972. 3. Biennan, C. W.: Pneumomediastinum and Pneumothorax Complicating Asthma in Children, Am. J. Dis. Child. 114: 42-50, 1967. 4. Chiles, D. G.: Pneumothorax, Pneumomediastinum, and Massive Subcutaneous Emphysema After a General Anesthetic, J. Oral Surg. 28: 845-47, 1970. 5. Fraser, R. G., and Pare, J. A. P.: Diagnosis of Diseases of the Chest, vol II, Philadelphia, 1970, W. G. Saunders Co.. pp. 1174-1179. 6. Gray, J. M., and Hanson, G. C.: Mediastinal Emphysema: Aetiology, Diagnosis, and Treatment, Thorax 21: 325-332, 1966. 7. Hamman, L.: Spontaneous Mediastinal Emphysema, Bull. John Hopkins Hosp. 64: l-21, 1939. 8. Hamman, L.: Mediastinal Emphysema, J. Am. Med. Assoc. 128: l-6, 1945. 9. Hunt, R. B., and Sahler, 0. D.: Mediastinal Emphysema Produced by Air Turbine Dental Drills, 3. Am. Med. Assoc. 205: 241-42, 1968. 10. Lillard, R. L., and Allen, R. P.: The Extrapleural Air Sign in Pneumomediastinum, Radiology 85: 1093-98, 1965. 11 Lloyd, R. E.: Surgical Emphysema as a Complication in Endodontics, Dent. J. 138: 393-394, 1975. 12 Meyerhoff, W. L., et al.: Mediastinal Emphysema After Oral Surgery, J. Oral Surg. 83: 477-79, 1973. 13 Noble, W. H.: Mediastinal Emphysema Resulting from Extraction of an Impacted Mandibular Third Molar, J. Am. Dental Assoc. 84: 368-70, 1972. I4 Sandler, C. M., et al.: Pneumoperitoneum, Pneumomediastinum, and Pneumopericardium Following Dental Extraction, Radiology 115: 539-40, 1975. 15 Schwartz, S. I., et al.: Principles of Surgery, ed. 2, New York, 1974, McGraw-Hill Book Co., Inc., p. 660. 16 Switzer, P., Pitman, R. G., and Fleming, J. P.: Pneumomediastinum Associated with Zygomatico-Maxillary Fracture, J. Cana. Assoc. Radiol. 25: 316-318, 1974. 17. Trummer, M. J., and Fosburg, R. G.: Mediastinal Emphysema Following Use of High-Speed Air Turbine Dental Drill, Ann. Thor. Surg. 9: 78-81, 1970. Reprint requests to: Dr. Joseph F. Piecuch Department of Oral & Maxillofacial Surgery Room L-7094 University of Connecticut Health Center School of Dental Medicine Farmington, Corm. 06032
