Pulmonary Interstitial Emphysema (PIE) Treatment & Management

Different treatment modalities have been used to manage pulmonary interstitial emphysema (PIE), with variable success. Admission/transfer to a neonatal intensive care unit (NICU) is indicated for these patients. A thoracentesis set should be readily available due to the possibility of air leak, including pneumothorax and pneumopericardium.

Although the primary risk factor for pulmonary interstitial emphysema, prematurity, is rarely preventable, attention should be given to the use of as little mechanical ventilatory support as is necessary for the patient's very fragile lungs.

Because pneumothorax is a known complication, anticipatory guidance for this possibility should be provided for all those caring for the infant. Appropriate personnel should be readily available to address this complication.

In addition to pulmonary treatment, the overall importance of appropriate nutritional management of these ill newborns cannot be overstressed. Most of these infants are treated with total parenteral nutrition and require diligent attention.

All infants with pulmonary interstitial emphysema need to be under the care of a neonatologist. In some cases, pediatric pulmonology and pediatric surgery consultations are appropriate.

Go to Emphysema and Emergent Management of Chronic Obstructive Pulmonary Disease (COPD) for complete information on these topics.

This conservative approach has been used with success and is most effective in infants with unilateral pulmonary interstitial emphysema. The infant is placed in the lateral decubitus position with the affected lung dependent. This therapy can result in plugging of dependent airways and improved oxygenation of the nondependent lung. The latter allows for overall decreased ventilatory settings. The combination of the above factors helps in resolution of pulmonary interstitial emphysema.^[16]

In different case studies of lateral decubitus positioning as a treatment of unilateral pulmonary interstitial emphysema in infants, pulmonary interstitial emphysema resolved in 48 hours to 6 days with minimal recurrence and a low failure rate. Lateral decubitus positioning should be considered as an early first-line therapy in the management of unilateral pulmonary interstitial emphysema. Lateral decubitus positioning has been used successfully for patients with bilateral pulmonary interstitial emphysema when one side is more significantly affected.

Many case reports detail successful treatment of infants with severe localized pulmonary interstitial emphysema by selective intubation of the contralateral bronchus. This maneuver decompresses the overdistended lung tissue and avoids exposing it to high positive inflationary pressures.^{[17, 18, 19]} Selective bronchial intubation of the right main bronchus is not a difficult procedure; the left side may be more difficult.

This procedure uses an endotracheal tube of the same diameter as for a regular intubation. However, the tube is inserted 2-4 cm beyond its usual position. It is introduced with the bevel on the end of the tube positioned so that the long part of the tube is toward the bronchus to be intubated. This increases the chance of entering the correct bronchus as the tube is advanced into the airway. Turning the infant's head to the left or right moves the tip of the endotracheal tube to the contralateral side of the trachea and may help in selective tube placement.

Weintraub et al have described a method for left selective bronchus intubation using a regular Portex endotracheal tube in which an elliptical hole 1 cm in length has been cut through half the circumference 0.5 cm above the tip of the oblique distal end.^[19] With the side with the elliptical hole directed to the left lung, left selective bronchus intubation can be easily and repeatedly accomplished.

Another method of selective intubation is the use of a small fiberoptic bronchoscope to direct the endotracheal tube tip into the desired bronchus. Selective intubation under fluoroscopy can also be considered.

Potential complications of the selective intubation/ventilation include the following:

• Atelectasis in the affected lung
• Injury to bronchial mucosa with subsequent scarring and stenosis
• Acute hypoventilation or hypoxemia if ventilating one lung is inadequate
• Excessive secretions
• Hyperinflation of the intubated (nonoccluded) lung
• Upper lobe collapse when intubating the right lung
• Bradycardia

Despite potential risks, selective bronchial intubation is a desirable alternative to lobectomy in a patient with persistent, severe, localized pulmonary interstitial emphysema causing mediastinal shift and compression atelectasis that is not responding to conservative management. This procedure should be attempted before any surgical intervention.

Keszler et al found that high-frequency jet ventilation (HFJV) was safe and more effective than rapid-rate conventional ventilation in the treatment of newborns with pulmonary interstitial emphysema.^[20] Their study in 144 newborns with pulmonary interstitial emphysema showed that with HFJV, similar oxygenation and ventilation was obtained at lower peak and mean airway pressures. These results suggested that less air would leak into the interstitial spaces in these infants.

Similar effects can be achieved by use of high-frequency oscillatory ventilation (HFOV). A study by Clark et al demonstrated the efficacy of HFOV in 27 low-birth-weight infants who developed pulmonary interstitial emphysema and respiratory failure while on conventional ventilation.^[21]

Overall survival in nonseptic patients was 80%. Surviving patients showed continued improvement in oxygenation and ventilation at an increasingly lower fraction of inspired oxygen (FiO₂) and proximal airway pressure with resolution of pulmonary interstitial emphysema, whereas nonsurvivors progressively developed chronic respiratory insufficiency with continued pulmonary interstitial emphysema from which recovery was not possible.

Clark et al hypothesized that interstitial air leak is decreased during HFOV because adequate ventilation is provided at lower peak distal airway pressures. Although this mode of ventilation has inherent risks, it can be a very effective tool in experienced hands for the treatment of severe diffuse pulmonary interstitial emphysema. Care must be taken in smaller infants who require a high amplitude to ventilate because the active exhalation during HFOV may cause small airway collapse and exacerbate gas trapping.

Lobectomy is indicated in a small number of patients with localized pulmonary interstitial emphysema when spontaneous regression is not occurring and medical management has failed.^{[22, 23, 24]} Although clear guidelines for surgical intervention are difficult to establish, lobectomy should be reserved for infants in whom the risks of recurring complications outweigh those of surgery. It seems most helpful in infants who develop severe lobar emphysema.

Case reports and/or case series describe a variety of other approaches for the management of pulmonary interstitial emphysema, including the following:

• A 3-day course of dexamethasone (0.5 mg/kg/d)^[25]
• Chest physiotherapy with intermittent 100% oxygen in localized and persistent compressive pulmonary interstitial emphysema^[26]
• Artificial pneumothorax^{[27, 28]}
• Multiple pleurotomies^[29]

Despite success claimed by the authors, the efficacy of these treatment modalities from these case reports seems questionable. With advancements in respiratory care, these treatment modalities rarely are used.

Surfactant

Prophylactic surfactant administration to infants (< 30-32 weeks' gestation) judged to be at risk of developing respiratory distress syndrome (RDS) compared with selective use of surfactant in infants with established RDS has been demonstrated to decrease the risk of pulmonary interstitial emphysema.^[30]

Meta-analysis of early surfactant replacement therapy with brief ventilation compared with later, selective surfactant replacement and continued mechanical ventilation suggests a trend towards a decreased incidence of air leak syndromes in premature infants in the early surfactant group. Early surfactant treatment, less invasive ventilatory support, or both could be responsible factors for the observed beneficial trend.^[31]

According to one report, in infants with respiratory distress, multiple doses of animal-derived surfactant extract resulted in greater improvements in oxygenation and ventilatory requirements, a decreased risk of pneumothorax, and a trend toward improved survival.^[32]

High-frequency ventilation

In a study comparing high-frequency positive pressure ventilation (HFPPV) to conventional ventilation, Pohlandt et al reported a reduction in the risk of pulmonary interstitial emphysema with HFPPV.^[33] Review of different trials of elective high-frequency oscillatory ventilation (HFOV) versus conventional ventilation for acute pulmonary dysfunction in preterm infants suggests an increase in the incidence of air leak syndromes, including but not limited to pulmonary interstitial emphysema in the HFOV group.^[34]

In contrast, a prospective randomized multicenter study of HFOV versus conventional ventilation in premature infants with RDS showed no difference in the incidence of pulmonary interstitial emphysema.^[9] Limited data regarding rescue HFOV for pulmonary dysfunction in the preterm infant also showed no difference in the rate of pulmonary interstitial emphysema.^[35]

Cochrane reviews of trials of elective high-frequency jet ventilation (HFJV) versus conventional ventilation for RDS demonstrated no significant difference in the incidence of air leak syndrome in the individual trials or in the overall analysis.^[36]

In summary, current literature suggests elective or rescue high-frequency ventilation does not prevent the development of pulmonary interstitial emphysema.

Other considerations

Different modes of conventional ventilation do not appear to affect the risk of pulmonary interstitial emphysema. No significant difference in the rate of pulmonary interstitial emphysema was found either in pooled analysis within subgroups or overall pooled analysis of trials comparing volume-targeted versus pressure-limited ventilation in the neonate.^[37]

Avoid use of high peak inspiratory pressure (PIP). Be careful (watch the manometer) during manual ventilation.

Monitoring for physical and psychomotor development in a neonatal follow-up care program or equivalent program is important because most infants with pulmonary interstitial emphysema are premature and are at risk for developmental delay. In addition, pulmonary interstitial emphysema has been associated with increased risks of intraventricular hemorrhage (IVH) and periventricular leukomalacia (PVL), which also increase the risks of developmental delay in these infants.

Patients with chronic lung disease may need pediatric pulmonology follow-up care.