AIR LEAK SYNDROME
Marina M. Perez-Fournier M.D. Neonatology Fellow MHMC
Pulmonary air leak
When air escapes from the lung into extra-alveolar spaces where it is not normally present Most common in newborn period. Iatrogenic pulmonary condition of the premature infant with immature lungs (mechanical ventilation)
Pulmonary air leak syndrome
Pulmonary Interstitial Emphysema Pneumothorax Pneumomediastinum Pneumopericardium Pneumoperitoneum Subcutaneous Emphysema
Pulmonary Interstitial Emphysema
Collection of gases outside the normal air passages Escape of air into pulmonary interstitium, lymphatic and venous circulation. Secondary to rupture (usually junction of the bronchiole and alveolar duct)
Pulmonary interstitial emphysema Risk Factors
Prematurity (< 32 weeks GA) VLBW (< 1,000 g) Low Apgar score (< 5 ) and need of resuscitation Positive pressure ventilation Use of Peak inspiratory pressure (PIP), Tidal volume (vT) & Inspiratory time (Ti)
RDS Meconium aspiration syndrome Amniotic fluid aspiration Infection Neonatal sepsis Pneumonia Pulmonary hypoplasia
Pulmonary interstitial emphysema Classification
Usually in the first 72 hrs of life
Acute ( less 7 days) or persistent Localized or diffused Unilateral or bilateral
Pulmonary interstitial emphysema Frequency
Currently is uncommon because of post natal surfactant, gentle ventilation and high frequency ventilation.
Premature Infant Underdeveloped lungs Inadequate surfactant
Vicious Cycle
Surfactant
COLLAPSE
CO2 O2
Mechanical Ventilation
RUPTURE
compliance Compression of lymphatic
Pulmonary interstitial emphysema Pathophysiology
Mechanical ventilation with large tidal volume increases the number of neutrophils and cytokines in the lungs and also the permeability of the capillary membrane, leading to pulmonary edema
Pulmonary interstitial emphysema Pathophysiology
Recent studies have demonstrated presence of free elastase and alpha 1-proteinase inhibitor as well as elastase-alpha 1- proteinase inhibitor in tracheal aspirate of neonates with severe RDS PIE infants appear to have free elastase activity in tracheal aspirate fluid.
Speer et al 1993, Pediatrics Jaarsmaet et al 2001, Pediatric Research
Pulmonary interstitial emphysema Diagnosis
Mainly a radiographic and pathologic diagnosis Blood gas show PCO2 and PO2 Increased respiratory support demand Increased lung volumes AP C-Xray :
linear, oval or spherical cystic air-containing spaces (1 mm to 1 cm) Pneumothorax Heart tends to get smaller intrathoracic pressure . lung volume
Left lung diffuse PIE
Bilateral diffuse PIE
Pulmonary interstitial emphysema Differential Dx
Bronchopulmonary dysplasia (BPD) (lucency is less linear) Respiratory distress syndrome Congenital cystic adenomatoid malformation (CCAM)
Pulmonary interstitial emphysema Complications
Loss of pulmonary compliance Epitheliazation of the interstitial air pockets Air embolus in pulmonary venous circulation Rupture of subpleural lymphatic blebs (pneumothorax)
Pulmonary interstitial emphysema Complications
BPD
Rupture of bronchial connections and release of air into the interstitium promotes edema and oxidant injury Cochran et al, B J Radiol 1994. Highest risk for VLBW infant, low GA and PIE in first 24 hrs of life. Gaylord et al, Pediatrics, 1985
Increased risk for IVH in pneumothorax. Hill et al, Pediatrics, 1982.
Pulmonary interstitial emphysema Treatment
Localized
Conservative management Decubitus position with affected side down Selective intubation of the main bronchus on the uninvolved side (10 days ODonovan 2001, 5 days Khashu 2005) Lobectomy
High frequency oscillatory ventilation (low volumes of gas and low pressure) Nelle et al, Intensive care med 1998.
Pulmonary air leak syndrome
Pulmonary Interstitial Emphysema Pneumothorax Pneumomediastinum Pneumopericardium Pneumoperitoneum Subcutaneous Emphysema
Pneumothorax
Pneumothorax refers to the presence of air or gas in the pleural cavity between the visceral and parietal pleura, which results in violation of the pleural space. There is a loss of intrapleural negative pressure causing lung collapse.
Pneumothorax Pathophysiology
The main physiologic consequences of a pneumothorax are a decrease in vital capacity and a decrease in PaO2 In a simple pneumothorax, air in the pleural space does not build up significant pressure but allows the lung to collapse 10-30% without further expansion of the pneumothorax.
Pneumothorax Pathophysiology
A complicated pneumothorax is progressive and consists of continued air leakage into the pleural space and progressive lung collapse. Tension pneumothorax is a life-threatening emergency It is caused when air enters the pleural space during inspiration but cannot exit during exhalation.
Pneumothorax Pathophysiology
The positive pressure results in collapse of the involved lung and a shift of the mediastinal structures to the contralateral side. This causes a decrease in cardiac output as a consequence of decreased venous return and leads to rapidly progressive shock and death if not treated
Pneumothorax Signs & symptoms
Increasing respiratory distress, including rapid breathing, grunting, nostril flaring, and chest wall retractions Difficulty hearing breath sounds when listening with a stethoscope Change in the location of heart or lung sounds when the organs are moved by the presence of air Changes in arterial blood gas levels (respiratory acidosis)
Pneumothorax Dx diff
Bornchogenic cyst Congenital lung malformation Cystic adenomatoid malformation Bronchogenic cyst Congenital lung malformation CCAM Hemothorax Pleural effusion
Pneumothorax Diagnosis
A tension pneumothorax should always be a clinical diagnosis since death can occur before the radiograph is taken or developed
Pneumothorax Diagnosis
When an infant is suspected of having a pneumothorax, anterior-posterior radiographs are taken in the supine position. Small pneumothoraces can be better visualized with lateral decubitus film with the affected side up. Transillumination of the chest may help to establish the diagnosis in the newborn infant.
Pneumothorax
Pneumothorax
Pneumothorax Treatment
No specific management for asymptomatic pneumothorax Infants with lung disease, the presence of pneumothorax accentuates the respiratory difficulty and requires intervention Full term with no mechanical ventilation: FIO2 100% in oxyhood up to 50 percent may improve the resolution of small uncomplicated pneumothorax
Thoracentesis (needle aspiration)
Emergent treatment of a symptomatic pneumothorax Localize site: 2nd-3rd intercostal space along midclavicular line Cleanse the area 22/24 g angio attached to 20 ml syringe with a stopcock Palpable 3rd rib at midclavicular line and insert needle above the rib Advance needle till air is withdrawn in syringe
Pneumothorax : chest tube
Tension pneumothorax and pneumothorax that develops in a mechanically ventilated infant usually need chest tube placement for definitive drainage. Equipment:
Chest tube set up Sterile field < 2 Kg use 10 Fr catheter >2 Kg Use 12 Fr catheter
Pneumothorax: chest tube
Procedure
Anterior placement (2nd-3rd intercostal space, midclavicular line) Posterior placement (4th , 5th , 6th intercostal space, anterior axillary line)
NIPPLE LINE IS 4TH INTERCOSTAL 1. Position patient 2. Select site 3. Cleanse area / sterile field 4. Infiltrate area with 0.5%-1% lidocaine
Pneumothorax: chest tube
5. Make small incision 1.5 cm in the skin over the rib just below the intercostal space where tube is to be inserted 6. Dissect tissue with hemostat. 7. Using tip of hemostat, puncture pleura just above the rib 8. Insert chest tube through open hemostat 9. Attach to suction 10. Secure with sutures 11. Apply Vaseline 12. CXR
Pulmonary air leak syndrome
Pulmonary Interstitial Emphysema Pneumothorax Pneumomediastinum Pneumopericardium Pneumoperitoneum Subcutaneous Emphysema
Pneumomediastinum
Pneumomediastinum consists of air in the mediastinal space Most cases are asymptomatic. Large collections of air may result in tachypnea and cyanosis Suspected on the routine newborn examination when the heart sounds are distant. The diagnosis is made on a chest radiograph Usually resolves spontaneously, and requires no specific treatment The patient should be observed closely for other air leaks, especially pneumothorax.
Pneumomediastinum
Pulmonary air leak syndrome
Pulmonary Interstitial Emphysema Pneumothorax Pneumomediastinum Pneumopericardium Pneumoperitoneum Subcutaneous Emphysema
Pneumopericardium
Rare condition caused by air in the pericardial space It can cause cardiac tamponade that is lifethreatening. Typically occurs in a mechanically ventilated preterm infant with severe RDS who also has pneumothorax and/or PIE Rare in an infant who does not require mechanical ventilation
Pneumopericardium
Clinically:
Abrupt onset of hemodynamic compromise due to cardiac tamponade Tachycardia and a narrowed pulse pressure Follow by bradycardia, hypotension, increased respiratory distress, and cyanosis The heart sounds may be muffled or distant The electrocardiogram may show low voltages with a small QRS complex.
Pneumopericardium
Diagnosis is confirmed by chest radiograph ( gas shadow does not extend beyond the reflection of the aorta and pulmonary artery) In life-threatening situations in which the diagnosis is strongly suspected, the diagnosis is made by a therapeutic pericardiocentesis
Pneumopericardium
Pneumopericardium
Management:
Infants who are asymptomatic may not need intervention (close monitoring) Ventilator pressures should be minimized
Pericardial drainage :
Symptomatic infants This procedure is both diagnostic and therapeutic
Pulmonary air leak syndrome
Pulmonary Interstitial Emphysema Pneumothorax Pneumomediastinum Pneumopericardium Pneumoperitoneum Subcutaneous Emphysema
Pneumoperitoneum Subcutaneous Emphysema
Pneumoperitoneum and subcutaneous emphysema are uncommon types of air leak Pneumoperitoneum may occur when extrapulmonary air decompresses into the peritoneal cavity The diagnosis is made on an abdominal radiograph and usually has little clinical significance It must be differentiated from intraperitoneal air due to a perforated viscus.
Subcutaneous emphysema typically occurs in the face, neck, or supraclavicular region. It typically presents as crepitus detected by palpation. It usually has no clinical significance, although large air collections in the neck may cause tracheal compromise
GENTLE VENTILATION
Goals of mechanical ventilation
Achieve and maintain adequate pulmonary gas exchange Minimize the risk of lung injury Reduce patient work of breathing Optimize patient comfort
EACH CHANGE IN VENTILATORY STRATEGY HAS A CONSEQUENCE
Gentle Ventilation
1999 Dr. Hudson proclaims the concept of VILI ventilator-induced lung injury VILI can induce biotrauma (cytokines) Premature infants with antecedent of lung injury (RDS) more prone to volutrauma and atelectrauma
Clark et al, Pediatrics 2000
Gentle Ventilation
Permissive hypercapnia Low tidal volumes Low Peak inspiratory pressure High rates Low inspiratpry time
Mariani et al, Pediatrics 1999 Carlo WA et al, J Pediatr 2002
Gentle Ventilation
First days of life (4 to 10 days) ELBW infants (500-1250 g) Results in
time on ventilator air leak BPD
Side effects are hyperkalemia, pulmonary vasc. resistance and acidosis
Mariani et al, Pediatrics 1999 Carlo WA et al, J Pediatr 2002
Permissive Hypercapnia
Strategy on which priority is given to the prevention or limitation of lung injury secondary to the ventilator by tolerating relatively high levels of PCO2
Hypocapnia in first days of life is related to CLD
Carlo WA et al, Minerva Pediatr 2004 Steven et al, Resp Care 2003
Permissive Hypercapnia
Mariani et al, Pediatrics 1999
49 preterm infants were randomized in 2 groups:
Normocapnia (35-45 mmHg)x 96 hrs Hypercapnia (45-55 mm Hg) x 96 hrs
Hypercapnic group extubated early No statistically significant differences in CLD
Permissive Hypercapnia
Carlo WA et al, J Pediatr 2002
220 mechanical ventilated infants BW 501-1000g Randomized to:
Normocapnia (PaCO2 < 48 mmHg) Hypercapnia (PaCO2 > 52 mmHg)
Need for mechanical ventilation at 36 week in normocapnia group was 16% vs 1% hyperCo2 No differences in death, CLD or IVH
Long vs. short I.T.
Kamlin et al 2004. Cochrane Database Syst Rev.
All randomized and quasi-randomized controlled trials enrolling mechanical ventilated infants Five studies (694 infants) Results: Long IT ( 0.5 sec) associated with air leak (RR 1.56), mortality (RR 1.26) and no impact on BPD Conclusion: infants with poorly compliant lungs should be ventilated with short IT Caution studies were conducted prior antenatal steroids and post-natal surfactant
Gentle Ventilation: RATE
Cochrane Central Register of Controlled Trials 2004
Meta-analyses of the RCT of high (>60bpm) versus low (30-40bpm) rates Increasing ventilator rate and reducing IT, mimicking the preterm infant's respiratory pattern Significant decrease in air leak (28% vs. 19%) and a shorter duration of ventilation with high rate No significant effect on CLD or death
High Frequency Ventilation
HFV useful in PIE There is not sufficient evidence to justify it as a primary treatment modality for RDS infants.
Steven et al, Resp Care 2003
Arterial Blood Gas
PH 7.20 PaO2 60-80 mmHg Pa CO2 45-55 mmHg
Questions
1.- List 5 risk factors for PIE 2.- Describe the physiopathology of PIE 3.- Long term complications of PIE 4.- Differential diagnosis of pneumothorax 5.- What is the severe complication of pneumopericardium 6.- What is gentle ventilation and what are the bloos gas permissible ranges of Ph, PaCO2 and PCO2 to prevent air leak syndrome and BPD
