INDEPENDENT PAPERS

Iatrogenic Pneumothorax and Mortality in Congenital Diaphragmatic Hernia

By Christopher Gibson and Eric W. Fonkalsrud

Los Angeles, California

�9 In a review of 22 infants who underwent surgi- cal repair of congenital diaphragmatic hernias, it was noted that one of the most common factors correlat- ing with death was perioperative tension pneumo- thorax. Each of the seven infants who died devel- oped an iatrogenic pneumothorax with air leak due to face-mask or endotracheal ventilation with pres- sures in excess of 34 cm H=O, or to thoracentesis. Only two infants with tension pneumothorax sur- vived. Infants who developed tension pneumothorax experienced severe respiratory distress at an earlier age and required more vigorous resuscitative mea- sures than those infants without an air leak.

INDEX WORDS: Congenital diaphragmatic hernia; tension pneumothorax.

C ONGENITAL posterolateral diaphrag- matic hernia, the predominant develop-

mental anomaly of the diaphragm, occurs in approximately one of every 2,200 live births. The malformation results from defective fusion of the pleuroperitoneal membrane with the other dia- phragmatic components at approximately 6 weeks gestation. 1 By the tenth week, when the viscera returns to the abdomen, if this membrane is incompletely fused, the major portion of the intestine or liver will migrate into the chest, compressing the ipsilateral lung. This results in pulmonary hypoplasia and displacement of the heart to the contralateral side. Cyanosis and respiratory distress with tachypnea usually occur shortly after birth.

The overall mortality rate for infants who suffer congenital diaphragmatic hernias with moderate to severe pulmonary hypoplasia has improved only slightly during the last decade despite application of several new resuscitative techniques; pulmonary insufficiency is the major contributing factor. All infants have transient pneumothorax without air leak on the ipsilateral side subsequent to surgical correction of the defect, owing to incomplete expansion of the hypoplastic lung; this does not displace the mediastinal contents or the heart to the opposite side. On the other hand, perioperative tension pneumothorax accompanied by air leak may

compress the only functioning lung tissue and is often fatal.

We reviewed the records of 22 infants with congenital posterolateral diaphragmatic hernias surgically repaired at UCLA Hospital during the decade from 1971 to 1981. The incidence of pneumothorax with air leak and its relationship to mortality were reviewed.

MATERIALS AND METHODS

During the past ten years, 12 males and l0 females with posterolateral congenital diaphragmatic hernias underwent surgical repair at UCLA Hospital. Birth weights ranged from 1.5 to 4.8 kg (mean, 3.0 kg). Seven defects occurred on the right and 15 were on the left side. Mortality was higher with right-sided defects (57%) than with those on the left (20%). The clinical features of the patients are summarized in Tables 1 and 2. More than 80% of the infants experienced respiratory distress during the first few hours of life. Clinical examination revealed nasal flaring, grunting, tachypnea, tachycardia, displacement of the heart sounds, and absence of breath sounds on the side of the hernia. The diagnosis was confirmed by chest X-ray in all patients.

Seventeen infants underwent surgical correction of the hernia during the first 36 hours of life (mortality rate, 41%). Preoperative management consisted of endotracheal intuba- tion, passage of a nasogastric tube, placement of an arterial catheter for-monitoring blood gases, and administration of intravenous sodium bicarbonate to treat acidosis. In eight of the infants an endotracheal tube was inserted prior to induc- ing anesthesia because of respiratory distress. Operative repair was performed under light inhalation anesthesia, dur- ing which time body temperature was maintained at 36 to 37~ by overhead infrared heating lamps and heated humid- ifed mist. The hernia defects were repaired with a single layer of interrupted nonabsorbable sutures. A chest tube was placed on the ipsilateral side and attached to water-seal drainage without suction until the hypoplastic ipsilateral lung has expanded (average time, five days). Postoperatively, the

From the Department of Surgery, UCLA School o f Medi- cine, Los Angeles, Cal. 90024.

Presented before the 15th Annual Meeting of the Pacific ..... Association of Pediatric Surgeons, Vancouver, BC, Canada,

May 13, 1982. Address reprint requests to Christopher Gibson, MD,

Dept of Surgery, UCLA School of Medicine, Los Angeles, CA, 90024.

�9 1983 by Grune & Stratton, Inc. 0022/3468/83/1804-0006501.00/0

Journal of Pediatric Surgery, Vol. 18, No. 5 (October), 1983 555

556 GIBSON AND FONKALSRUD

Table 1. Survivors Following Diaphragmatic Hernia Repair

Pt Wt Age at Hypoplastic Tension Respiratory No, Sex (kg) Side Operation Lungs Pneumothorax Pressures

1 F 1.5 L 2 mo Mod

J 2 F 3.5 R 30 hr Mild

3 M 2.4 L 3 mo Mild 4 M 3.2 L 36 hr Mod + 10-20 cm

6 M 3.9 R 24 hr Mild

6 M 2.9 L 3 mo Mild

7 M 4,0 L 6 hr Mod 23/2 cm

8 M 3.1 L 16 hr Mod

9 F 2.9 L 3 wk Mild

10 F 3,0 R 20 hr Mild 10-20 cm

11 F 2.5 L 6 hr Mild

12 M 3.4 L 5 hr Mild

13 F 2,8 L 3 d Mild } 10-20 cm

14 M 2.3 L 10 hr Mild + >34 cm

15 M 3.5 L 10 hr Mod 20/2 cm

patients were monitored closely with frequent arterial blood gas determination in the Neonatal Intensive Care Unit. Six of the patients received pancuronium for paralysis and/or tola- zoline for pulmonary vasodilation. Five infants were repaired after 36 hours without mortality (Table 3).

A unilateral tension pneumothorax occurred in nine of the infants and a bilateral pneumothorax subsequently developed in five of them. During the same 10-year period of study, eight infants with posterolateral congenital diaphragmatic hernias, transferred to UCLA Hospital, died before operative treatment could be initiated; seven had pneumothorax with air leak.

RESULTS

In each of the 17 infants who underwent surgical correction of diaphragmatic hernias during the first 36 hours of life, the presence of

pneumothorax with air leak was closely corre- lated with mortality (Fig. 1). In each of the seven patients who died, an associated tension pneumo- thorax on the ipsilateral or contralateral side from the defect became evident preoperatively or postoperatively (Table 4). In five patients, ipsila- teral tension pneumothorax was noted on chest x-ray preoperatively, and occurred following a forceful manual ventilation or thoracentesis. Four of these subsequently developed a contra- lateral pneumothorax with air leak during the perioperative period, resulting in progressive car- diopulmonary distress and eventual death. Of the 15 infants who survived, only two (13%) had an associated pneumothorax with air leak on the

Table 2. Deaths Following Diaphragmatic Hernia Repair

Maximum Pt Age at Diagnostic Preop Respiratory No. Sex Wt S ide O p e r a t i o n Thoracentesis Air Leaks Pneumothorax Pressures

16 F 3.0 R 12 hr Postop L - Postop L >34 cm

17 M 3.0 R 1 ~ hr Preop L then R + Preop L* 40 cm

Preop R t 18 M 2.7 R 2 hr Preop R + Preop R* 40 cm

Postop R* *

19 F 3.0 L 20 hr No -- Postop R** 34 cm

then L**

20 F 3.0 L 5 hr No + Preop R* 40 cm

then L*

Postop R * * 21 M 3.7 L 12 hr Preop L + Preop L t 34 cm

Postop R* *

then L**

22 F 3.0 R 6 h(' Proep L + Preop R* 34-66 cm

Postop L * *

* Hand ventilation.

tThoracentesis.

* * Respirator.

PNEUMOTHORAX IN DIAPHRAGMATIC HERNIA

Table 3. Age at Repair Related to Pneumothorax and Morta l i t y

No. of Age Patier~s Pneumothorax Mortality

<36 hr 17 9 7

>36 hr 5 0 0

ipsilateral or contralateral side. None of those who experienced bilateral pneumothorax with air leak survived. In eight of the nine patients with tension pneumothorax, it was evident that the air leak was iatrogenic.

Moderate to severe hypoplasia of both the ipsilateral and contralateral lung was observed in all the patients who died, compared to moderate to severe ipsilateral hypoplasia in only six of the 15 who survived. The only patient surviving pneumothorax and air leak in association with hypoplastic lung developed the problem postop- eratively, secondary to diagnostic thoracentesis. Another survivor also developed a pneumothorax following operation and although it was on the contralateral side, the ipsilateral lung expanded fully within 24 hours. In both of these patients, the air leaks were sealed within 24 hours, permit- ting removal of the chest tube within two to three days.

Table 4. Air Leak Related to Mortality

Patients Survivors Deaths Total

557

Preop:

Air leak 0 5 5 No air leak 15 2 17 ~ 22

Postop: Air leak 2 7 9 No air leak 13 0 13 I~22~-

In none of the patients was prematurity a significant factor relative to pneumothorax or mortality; all who died were the products of full-term gestation. Of the 22 patients, seven (32%) had associated congenital malformations in addition to malrotation of the intestine.

D I S C U S S I O N

The clinical experience at UCLA Hospital during the past decade suggests that pneumotho- rax with air leak associated with congenital posterolateral diaphragmatic hernia has more than an incidental relationship to the patients surviving surgical repair during the first few days of life. In each of the infants with tension pneu- mothorax, an instance could be identified during which overly aggressive face-mask ventilation, manual ventilation through an endotracheal

Fig. 1. (A} Chest roentgenogram of infant w i th a left congenita| posterolateral diaphragmatic hernia. (B) Unrecognized contralateral tension pneumothorax which developed while ventilated with alveolar pressures in e x c e s s of 34 cm H=O postoperatively. The lef t lung shows severe hypoplasia.

558 GIBSON AND FONKALSRUD

tube, thoracentesis, or ventilator support with alveolar ventilation pressures in excess of 34 cm H20 preceded pneumothorax development. Al- though these infants displayed more severe pul- monary hypoplasia and were compromised by immediate respiratory problems at birth, requir- ing heroic therapeutic and resuscitative mea- sures, the addition of pneumothorax with air leak produced a marked change in their clinical course, leading to death in all but two cases.

Thoracentesis as a diagnostic or therapeutic maneuver in a cyanotic infant with poor breath sounds on one side of the chest should be avoided unless a chest roentgenogram clearly indicates that no diaphragmatic hernia is present. Six of the nine infants with tension pneumothorax from the present study had thoracentesis by a member of the neonatology staff, other than a surgeon, together with aggressive face-mask ventilation, and it is not clear which contributed most to the pneumothorax; however, four of these patients died. The use of ventilatory pressures in excess of 34 cm H20 caused pneumothorax with air leak in almost all infants in whom pressures at this level were recorded (Table 5). When tension pneumo- thorax occurred in association with manual ven- tilation, it was probably because alveolar pres- sures were being similarly exceeded.

Srouji and colleagues 2 recently called atten- tion to barotrauma, complicating intermittent positive pressure ventilation as a source of alveo- lar overdistension and rupture, causing intersti- tial emphysema. In their patients, tension pneu- mothorax associated with the use of intermittent positive pressure breathing was much more fre- quent in infants who died than in survivors. The pulmonary vasculature appears to respond to hypoxia and acidosis by increasing pulmonary vascular resistance. 3 The effect for the infant is reversal to a pattern of persistent fetal circula- tion in which the pulmonary vascular resistance is high and blood flow is diverted through the foramen ovale and ductus arteriosus. 4 A deterio- rating cycle ensues in which increased right- to-left shunting aggravates hypoxia and acido- sis. 5 The addition of perivascular air compression

Table 5. Maximum Respirator Pressures Related t o

Mortal i ty

Pressures (PIP) Survivors Deaths

>--34 cm 1 7

--<34 cm 14 0

of the main pulmonary arterioles may also impede blood flow, producing the air-block syn- drome with circulatory failure, myocardial decompensation, and possible death.

Although avoiding aggressive ventilation and thoracentesis may reduce the incidence of pneu- mothorax with air leak, there still exists a group of patients in whom adequate ventilation may not be possible without resorting to increasing inspi- ratory pressures. In these infants the use of bilateral prophylactic tube thoracostomies may represent an important option to prevent tension pneumothorax with its resulting hypoxia and increasing pulmonary vascular resistance. Other considerations include ventilation with high- frequency small-volume oscillations which have been shown in experimental animals with injured lungs to provide adequate gas exchange using minimal airway pressures. 6 Lastly, Grosfeld et al 7 have described a group of infants with tension pneumothorax unresponsive to multiple chest tube insertions who were managed successfully in nine out of ten cases by emergent thoracotomy with suturing of the iatrogenic bronchopleural air leaks.

Inasmuch as iatrogenic pneumothorax with air leak contributes significantly to mortality in infants with congenital diaphragmatic hernia, precautions should be taken to prevent this com- plication. Diagnostic or therapeutic thoracente- sis, face-mask ventilation and endotracheal ven- tilation with pressures in excess of 34 cm H20 must especially be avoided. Moreover, the possi- ble benefits of bilateral prophylactic tube thora- costomies, or oversewing a persistent pulmonary leak in an infant with severe respiratory distress, should be considered in order to prevent the high mortality resulting from persistent perioperative tension pneumothorax.

REFERENCES

1. Moore KL: The developing human. Clinically Oriented emphysema and tension extrapulmonary air. J Pediatr Surg Embryology, 1973, pp 132-135. 15:45, 1981

2. Srouji MN, Bucj B, Downes J J: Congenital diaphrag- matic hernia: Deleterious effects of pulmonary interstitial 3. Rudolph AM, Yuan S: Response of the pulmonary

PNEUMOTHORAX IN DIAPHRAGMATIC HERNIA 559

vasculature to hypoxia and H+ ion concentration changes. J Clin Invest 45:399, 1966

4. Collins DL, Pomerance J J, Travis KW, et al: A new approach to congenital posterolateral diaphragmatic hernia. J Pediatr Surg 12:149, 1977

5. Dibbins AW, Wiener ES: Mortality from neonatal diaphragmatic hernia. J Pediatr Surg 9:653, 1974

6. Bohn D J, Butter W, Froese AB, Bryan AC: Ventilation by high frequency oscillation. Fed Proc 38:951, 1979

7. Grosfeld JL, Lemons JL, Ballantine TVN, Schreiner RL: Emergency thoracotomy for acquired bronchopleural fistula in the premature infant with respiratory distress. J Pediatr Surg 15:416, 1980