Postoperative pneumomediastinum and pneumothorax following orthognathic surgery

J Oral Maxillofac

Surg

44.137-141.1986

Postoperative Pneumomediastinum Pneumothorax Following Orthogna thic Surgery DONALD B. EDWARDS, DDS,* ROBERT B. SCHEFFER, IRA JACKLER, MD*

and

DDS,t AND

Report of Cases

Pneumomediastinum and pneumotherax can be life-threatening complications of oral and maxillofacial surgery. There are two mechanisms for the introduction of air into the pleural or mediastinal compartments. The first is by an increase in intraalveolar pressure with a subsequent rupture of a perivascular bleb followed by the extravasation of air through the interstitial space into the pleural and mediastinal spaces: the second is by the traumatic disruption of the chest wall or cervical fascia.’ Postoperative factors in the dental patient that might lead to a sudden increase in intra-alveolar pressure include choking, coughing, mucous plugging, or vigorous ventilatory support either with mechanical ventilation or an ambu bag. There are numerous reports in surgical literature of dissection of air from above through the cervical fascial planes.?-” Reported cases include repair of facial fractures, surgical removal of teeth, antral irrigation, and the use of high-speed dental engines. The occurrence of pneumothorax-pneumomediastinum in two patients who underwent orthognathic surgery is reported. An awareness of the clinical presentation and the pathophysiology of these two life-threatening conditions is important for the oral surgeon.

Case 1 A 16-year-old Caucasian female presented for surgical correction of apertognathia with posterior vertical maxillary excess. The surgical treatment plan consisted of a two-piece Le Fort I osteotomy with posterior impaction and a horizontal reduction genioplasty. Review of the patient’s medical history was unremarkable. Results of the physical examination and preoperative laboratory studies including chest radiographs were unremarkable (Fig. 1). Following completion of a two-piece Le Fort I osteotomy and horizontal reduction genioplasty, the patient was taken to the recovery room in stable condition with the nasoendotracheal tube in place. No difficulties were experienced at the time of surgery. At 14 hours postoperatively, the patient experienced respiratory distress, which presented as perioral cyanosis, cyanosis of the nail beds, and decreased breath sounds bilaterally. The patient was ventilated with an ambu bag for approximately 30 seconds, and the nasoendotracheal tube was irrigated, which produced a large amount of thick mucous material. This resulted in an improvement in breath sounds bilaterally. Subsequent to these resuscitative measures, arterial blood gases revealed a PO, of 98 mmHg, PcoZ of 54 mmHg and a pH of 7.136 on 40% humidified oxygen. The chest radiograph revealed bilateral subcutaneous emphysema of the soft tissues of the neck (Fig. 2). This was accompanied by crepitation in the supraclavicular areas. The patient was continued on mechanical ventilation with 40% oxygen. Subsequent blood gases revealed a PO? of 73.6 mmHg Pco? of 41.9 mmHg, and pH of 7.33. A subsequent radiograph revealed the development of a left pneumomediastinum and a left pneumothorax with minimal collapse of the left lung (Fig. 3). Cardiac auscultation revealed a pericardial crunch indicative of air in the pericardial sac. The patient was continued on supplemental oxygen and nasoendotracheal intubation. A thoracic SLII-gery consultation did not recommend placement of a closed thoracostomy tube for drainage of the left pneumothorax. The chest radiograph showed resolution of the pneumomediastinum and pneumothorax. and attempts to mobilize secretions via pulmonary therapy were continued (Fig. 4). On the third postoperative day the patient was able to tolerate a full liquid diet, and at the time of discharge there was only a slight left pneumomediastinum and minima1 palpable suprascapular subcutaneous emphysema (Fig. 5). Follow up after a six-month period re-

* Formerly Chief Resident, Department of Dentistry, Division of Oral and Maxillofacial Surgery, University Hospital of Jacksonville; Presently staff oral and maxillofacial surgeon. Yokota ABS. Japan. t Director of the Division of Dental Education and Associate Professor and Chairman, Department of Oral and Maxittofaciat Surgery, University Hospital of Jacksonville/Jacksonville Health Education Programs, Inc., University of Florida, 580 West Eighth Street, Jacksonville, Florida 32209. i In the private practice of pulmonary medicine, Jacksonville, Florida. Address correspondence and reprint requests to Dr. Scheffer: Department of Oral and Maxillofacial Surgery. University of Florida, 580 W. Eighth St., Jacksonville, FL 32209.

137

138

POSTOPERATIVE

FIGURE

1 (/&,

top).

bottom).

FIGURE

2 (I&.

FIGURE

3 (right. top).

FIGURE mothorax.

4 (right,

Preoperative

chest

bottom).

radiograph

Chest

AND PNEUMOTHORAX

radiograph.

Post-resuscitation Chest

PNEUMOMEDIASTINUM

chest

radiograph

demonstrating

radiograph

showing

demonstrating

the pneumomediastinum partial

resolution

bilateral

subcutaneous

and left apical

of the pneumomediastinum

emphysema. pneumothorax. and total resolution

of the pneu

EDWARDS ET AL.

FIGURE 5 (left, rap).

Chest radiograph taken at time of discharge from hospital shows a slight pneumomediastinum

FIGURE 6 (I&, botrom). FIGURE 7 (right. top).

Preoperative

chest radiograph.

Postextubation

chest radiograph.

FIGURE 8 (right, borrom).

Chest radiograph taken on the second postoperative

day demonstrating

remaining.

small apical pneumothorax.

140

POSTOPERATIVE

PNEUMOMEDIASTINUM

AND PNEUMOTHORAX

of 40 mmHg, and a pH of 7.40. On the evening of the second postoperative day, the patient again became increasingly combative. Clinical examination revealed bilateral subcutaneous emphysema of the supraclavicular tissues. Auscultation revealed bilateral scattered rhonchi and pericardial crunch. A chest radiograph revealed a small left apical pneumothorax (Fig. 8). Arterial blood gases on 50% oxygen revealed a PO, of 71 mmHg, a Pco, of 41 mmHg, and a pH of 7.43. Because of the patient’s refusal of supplemental oxygen. an arterial blood gas was drawn on room air. which revealed a PO? of 71 mmHg, a Pco2 of 42 mmHg, and a pH of 7.43. Because of the satisfactory arterial blood gases and clinical condition, the patient was transferred to the ward and followed with daily chest radiographs. The patient’s had subsequent hospital course was uneventful with resolution of the subcutaneous emphysema and pneumomediastinum (Fig. 9). When the patient was examined five months postoperatively, she had no evidence of sequelae secondary to the postoperative complication. Discussion

FIGURE 9. Chest radiograph taken at discharge from the hospital showing resolution of the pneumothorax and the pneumomediastinum. vealed

no significant

sequelae

from the postoperative

complication. Case 2 A 21-year-old Caucasian female presented for surgical correction of maxillary protrusion and mandibular prognathism. Surgical treatment plan consisted of a Le Fort I osteotomy. bilateral sagittal split osteotomies, and horizontal reduction genioplasty. Review of the patient’s medical history was unremarkable. Results of the preoperative physical examination and laboratory studies including chest radiographs were unremarkable (Fig. 6). The patient underwent a Le Fort I osteotomy, bilateral mandibular sagittal split osteotomies. horizontal reduction genioplasty, and was taken to the recovery room in satisfactory condition with the nasoendotracheal tube in place. No surgical or pulmonary complications were experienced during the intraoperative period. The patient received moist humidified oxygen (40%) by T-tube. Postoperative medications included morphine sulfate for pain, phenergan for nausea, and decadron for the postoperative edema. Postoperative arterial blood gases revealed a PO? of 46.5 mmHg, Pco, of 39.9 mmHg. and pH 7.41 on 40%, oxygen. The impression at that time was that the patient had developed microatelectasis of the lung bases, which caused the hypoxemia. The following morning at 5:00 am the patient complained of increasing respiratory distress. Arterial blood gases with 40% oxygen via T-tube through the nasoendotracheal tube revealed a PO? of 55 mmHg. a Pco, of 36 mmHG, and a pH of 7.45. The patient was continued on supplemental oxygenation and nasoendotracheal intubation. At 4:00 pm on the second postoperative day, the patient became increasingly violent. breaking her restraints and extubating herself. The chest radiograph at that time was unremarkable (Fig. 7). The patient was continued on SO% oxygen via a face mask: arterial blood gases revealed a PO, of 106 mmHg. a Pco,

These cases are examples of life-threatening pneumomediastinum and pneumothorax that occurred postoperatively following extensive oral and maxillofacial surgery. The two major mechanisms for introduction of air into these compartments include increased intraalveolar pressure with subsequent rupture of a perivascular bleb, and the traumatic introduction of air through the cervical fascia. ’ These was no evidence of traumatic intubation or unusual disruption of the cervical fascia in these two patients. The first patient’s respiratory distress seemed to coincide with the introduction of mediastinal and pleural air probably secondary to increased intra-alveolar pressure from mucous plugs plus vigorous ventilation with an ambu bag. It is possible that the mucous plug provided a oneway valve whereby air was introduced into the intra-alveolar space during the inspiratory efforts, and the subsequent trapped air resulted in an increase in alveolar pressure.‘? The etiology of the pneumothorax and pneumomediastinum in the second patient is less apparent. It might be concluded that there was a small tear in the fascial planes during surgery and, with subsequent positive pressure ventilation, there was an increase in the diameter of the tear and subsequent pneumomediastinum. ” Alternatively. the ventilatory support provided to clear the microatelectasis may have produced an increase in intra-alveolar pressure and subsequent rupture of perivascular alveoli.” Reports of increased air trapping through a closed glottis with increased thoracoabdominal straining seems unlikely in these cases since both incidents occurred in intubated patients. The treatment of both patients consisted of continued supplemental oxygenation as well as pulmonary physiotherapy to keep the airways free of

141

ARAGON ET AL.

mucous

plugs. Attempts should be made to apply as little positive inspiratory pressure as possible and to ensure that expiratory efforts are not accompanied by marked increases in intra-alveolar pressure as might be seen with occluded nasotracheal tubes. With increase in size of the pneumothorax and compromise of arterial oxygenation, a closed-thoracostomy tube may be needed to release the increased pleural pressure and re-expand the collapsed lung. Breathing 100% oxygen will tend to increase reabsorption in a pneumothorax and pneumomediastinum. With washout of the blood nitrogen there will be an increased gradient of nitrogen from the pleural space air to blood resulting in an increased tendency to absorb the air into the bloodstream. Summary

Pneumomediastinum and pneumothorax are rare complications in the postoperative oral and maxillofacial surgery patient. Review of the sequence of events relating to these two life-threatening conditions emphasizes the importance of awareness of the clinical presentation and pathophysiology of these conditions as well as the need for judicious pulmonary physiotherapy in the intubated patient. Acknowledgments The author thanks Major Charles W. Elwell, USAF, DC, who presented this paper on behalf of Dr. Edwards before the Society

.I Oral Maxillofac 44 141-144,

of Air Force Clinical Surgeons 32nd Annual Symposium, Biloxi. Mississippi, on April 18. 1984.

References 1. Fraser RG, Pare JAP: Diagnosis of Diseases of the Chest. Philadelphia, WB Saunders, 1970, pp I174- 1179 2. Andsberg V. Axell T: Mediastinal emphysemas as a complication of dental treatment. Ondontol Ogisk Revy 23:21. I972 3. Hunt RB, Sakler OD: Mediastinal emphysema produced by air turbine dental drills. JAMA 205:24l, 1968 4. Lloyd RE: Surgical emphysema as a complication in endodontics. Br Dent J 138:393. 1975 5. Meyenhoff WL, Nelson R. Fry WA. et al: Mediastinal emphysema after oral surgery. J Oral Surg 3 1:477, 1973 6. Noble WH: Mediastinal emphysema resulting from extraction of an impacted third molar. J Am Dent Assoc 84:368. 1972 7. Sandier CM, Libshitz HI. Marks G, et al: Pneumoperitoneum. pneumomediastinum, and pneumopericardium following dental extraction. Radiology I l5:539, 1975 8. Schwartz Sl, Lillehei RC, Shires GI, et al: Principles of Surgery. 2nd ed. New York, McGraw-Hill. 1974, p 660 9. Switzer P, Pitman RG. Flemming JP: Pneumomediastinum associated with zygomatic-maxillary fracture. J Can Assoc Radio1 25:3 16, 1974 IO. Trummer MJ, Fosburg RG: Mediastinal emphysema following use of high-speed air turbine dental drill. Ann Thor Surg 9:78. 1970 II. Peicuch JF, West RA: Spontaneous pneumomediastinum associated with orthognathic surgery. J Oral Surg 48:506, 1979 12. Schulman A. Fataar S, Van Dor Spuy JW, Morton PCG, Crosier JH: Air in unusual places: some causes and ramifications of pneumomediastinum. Clin Radio1 33:301. 1982 13. Estafanous RG, Viljoen JF, Barsoum KN: Diagnosis of pneumothorax complicating mechanical ventilation. Anesth Analg 54:730. 1975

Surg

1966

Pneumomediastinum and Subcutaneous Cervical Emphysema during Third Molar Extraction Under General Anesthesia STEVEN B. ARAGON,

DDS, M. FRANKLIN DOLWICK, STEVEN BUCKLEY, DDS

Pneumomediastinum and cervical subcutaneous emphysema may arise from several causes.‘,” Dental and oral surgical procedures have been reReceived from the Department of Oral and Maxillofacial Surgery, University of Texas Health Sciences Center, San Antonio, Texas. Address correspondence and reprint requests to Dr. Aragon: University of Texas Health Science Center, Department of Oral and Maxillofacial Surgery, 7703 Floyd Curl Drive, San Antonio. TX 78284.

DMD, PI-ID, AND

lated to the development of pneumomediastinum and cervical subcutaneous emphysema through the use of high-speed air turbine drills.3-10 Trauma resulting in facial fractures’1-‘4 or trachea bronchial tearsIs has also produced extra-pleural air. Endotracheal intubation and mechanical ventilation may result in pneumothorax, pneumomediastinum, pneumoperitoneum, and subcutaneous emphysema. 16-r9 Spontaneous pneumomediastinum and cervical