PULMONARY INTERSTITIAL EMPHYSEMA CARE

Medical Care: Different treatment modalities have been used to manage PIE, with variable success.
• Lateral decubitus positioning
o This conservative approach has been used with success and is most effective in infants with unilateral PIE. The infant is placed in the lateral decubitus position with the affected lung in a dependent position. 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 PIE.
o In different case studies of lateral decubitus position as a treatment of unilateral PIE in infants, PIE 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 PIE. Lateral decubitus positioning has been used successfully for patients with bilateral PIE when one side is affected more significantly.

• Selective main bronchial intubation and occlusion
o Many case reports exist of successful treatment of severe localized PIE in infants with selective intubation of the contralateral bronchus to decompress the overdistended lung tissue and to avoid exposing it to high positive inflationary pressures. Selective bronchial intubation of the right main bronchus is not a difficult procedure; the left side may be more difficult. The endotracheal tube of the same diameter as for a regular intubation 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.

o 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. With the side with the elliptical hole directed to the left lung, left selective bronchus intubation can be accomplished easily and repeatedly. 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 also can be considered.

o Potential complications of the selective intubation/ventilation are 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 or nonoccluded lung, upper lobe collapse when intubating the right lung, and bradycardia. Despite potential risks, selective bronchial intubation is a desirable alternative to lobectomy in a persistent, severe, localized PIE causing mediastinal shift and compression atelectasis and not responding to conservative management. This procedure should be attempted before any surgical intervention.

• High-frequency ventilation
o Keszler et al studied use of high-frequency jet ventilation (HFJV) in 144 newborns with PIE. They concluded that HFJV was safe and more effective than rapid-rate conventional ventilation in the treatment of newborns with PIE. With HFJV, similar oxygenation and ventilation was obtained at lower peak and mean airway pressures, suggesting that in infants with PIE a reduction in the amount of air leaking into the interstitial spaces would occur.
o Similar effects can be achieved by use of HFOV.
- In a study by Clark et al, 27 low birth weight infants who developed PIE and respiratory failure while on conventional ventilation were treated with HFOV. 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 PIE, while nonsurvivors progressively developed chronic respiratory insufficiency with continued PIE from which recovery was not possible. Overall survival in nonseptic patients was 80%.
- They found HFOV to be effective in the treatment of PIE and 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 PIE. 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.

• Other treatment modalities
o Case reports and/or case series describe different approaches for the management of PIE, including 3-day course of dexamethasone (0.5 mg/kg/d), chest physiotherapy with intermittent 100% oxygen in localized and persistent compressive PIE, artificial pneumothorax, and multiple pleurotomies.
o Despite success claimed by the authors, the efficacy of these treatment modalities seems questionable. With advancements in respiratory care, these treatment modalities rarely are used.

Surgical Care: Lobectomy is indicated in a small number of patients with localized PIE when spontaneous regression is not occurring and medical management has failed. Although clear guidelines for surgical intervention are difficult to establish, it 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.

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

Diet: The overall importance of appropriate nutritional management of ill newborns cannot be overstressed. Most of these infants are treated with total parenteral nutrition and require diligent attention.

Further Inpatient Care:
• Admission/transfer to a NICU is indicated.
• Keep a thoracentesis set handy and keep the possibility of air leak, including pneumothorax and pneumopericardium, in mind.

Further Outpatient Care:
• Monitoring for physical and psychomotor development in a neonatal follow-up care program or equivalent program is important because most infants with PIE are premature and are at risk for developmental delay. In addition, PIE has been associated with increased risks of 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.

Deterrence/Prevention:
• Surfactant
o Four of the 5 randomized controlled trials for the prophylactic use of surfactant in premature infants with RDS noted a significant reduction in the incidence of PIE.
o Metaanalysis of the different trials suggests that prophylactic administration of surfactant leads to significant reduction in the risk of PIE.

• High-frequency ventilation
o In a study comparing high-frequency positive pressure ventilation (HFPPV) to conventional ventilation, Pohlandt et al reported a reduction in the risk of PIE with HFPPV. Review of different trials of elective 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 PIE in the HFOV group
o A recent prospective randomized multicenter study of HFOV versus conventional ventilation in premature infants with RDS showed no difference in the incidence of PIE. Limited data regarding rescue HFOV for pulmonary dysfunction in the preterm infant also showed no difference in the rate of PIE.
o Cochrane reviews of trials of elective 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.
o In summary, current literature suggests that elective or rescue high-frequency ventilation does not prevent the development of PIE.

• Other considerations
o Avoid use of high peak inspiratory pressure (PIP).
o Be careful (watch manometer) during manual ventilation.

Complications:
• Death
• Respiratory insufficiency
• Other air leaks
o Pneumomediastinum
o Pneumothorax
o Pneumopericardium
o Pneumoperitoneum
o Subcutaneous emphysema (rare)
• Massive air embolism
• Chronic lung disease (CLD) of prematurity
• Intraventricular hemorrhage
• Periventricular leukomalacia

Prognosis:
• Long-term follow-up data are scarce.
• Gaylord et al demonstrated a high (54%) incidence of CLD in survivors of PIE compared with their nursery's overall incidence of 32%. In addition, 19% of the infants developed chronic lobar emphysema; 50% received surgical lobectomies