☛ Incidence – 1:2500
☛ M:F – 2:1
☛ Lt > Rt  -5:1

Present as a true neonatal emergency requiring rapid resuscitation – correction of metabolic acidosis, fluid deficit, correction of hypothermia & baby prepared for emergency sx.

Embryology

• Failure of closure posterolateral part of diaphragm ( foramen of Bochdalek) or non fusion of anterior ,lateral or central portion of diaphragm retrosternaly ( Foramen of morgagni) by the 7- 8^th  wk of gestation produce debects in diaphragm.
• Slowly the growing gut or abdominal viscera migrate into the pleural cavity and causes vertilatory and circulatory crisis with pulmonary hypoplasia .
• The time at which thorax gets involved is important as it decides the degree of pulmonary hypoplasia and prognosis .

  Pathophysiology

Migration of Abdominal viscera into Thorax
           ⤋                                                                       ⤋                                                      ⤋
Medistinal shift                                           compression atelectasis                  Lung hypoplasia
           ⤋                                                                       ⤋                                                      ⤋
↓ed venous return                                       shunt &  hypoxia                               Resparatory Acidosis
           ⤋                                                                       ⤋                                                      ⤋
↓ed cardiac output                                     Inadequate vent.                               Met & Resp. Acidosis

 

• The spectrum of clinical presentation varies ,depending upon the period of lung invasion and pulmonary agenesis
• The commonest site is left sided foramen of Bochdalok.

Causes of hypoxia in  CDH

• Atelactasis – compression of developed lung
• Pessistent pul. hypoplasia due to ↓ed bronchopulmonary generation & pul vasculature
• Persistent pulmonary HTN
• Return of fetal circulation leading to R -> it shunt through ductus arteriosus or foramen ovale.
• Systemic hypotension following kinking of major blood vessels.

Classification of CDH

1. Absent diaphragm – very rare
2. Diaphragmatic hermia
   I  Posterolateral Foramen of Bochdeck -80 %
   II Anterior
   III  para-esophageal
   I V   Eventration rare

Assement of severity of pulmonary hypoplasia

I

•  PAO2 –PaO2 difference > 500 mm Hg  with 100 %  O2 –  predicts  nonsurvival
•  400 – 500 mm Hg   -> survival uncertain
•  < 400 mm Hg -> Better prognosis

II    Bohm’ index

☛ Ventilatory index -> Mean airway pressure X   RR
☛ Paco2 < 40 mm Hg VI < 1000   -> Always survive
☛ Paco2 > 50mm Hg   VI < 1000 ->   usually dieS
☛ Paco2 < 40 mmHg   VI > 1000 -> usually die

III   Echocardiography, pulmonary angiography , cardiac catheterization

Clinical Features

• Cyanosis
• Tachypnea, absent heart sound in left side of chest.
• Scaphoid abdomen, barrd chast
• X – ray chart -> Gas filled bowel in hemithorax
• Radiopaque dye the narogastic tube delinetes the bowel in chest .

Monitoring

• Precordial / esophageal stethoscope
• Pulse oximeter above or below nipple for preductal & postductal SpO2
• ECG
• Acid –base status
• Invasive BP monitoring, Rt radial Arterial monitoring for preductal PaO2 .
• CVP monitoring
• monitoring – esophagial ,rectal
• EtcO2

Surgical correction

• Surgical repair is not an emergency unless the contests of hernia are incarcerated.
• Correction of fluid deficit ,acidosis, improved ventilation & ECMO maintenance for indicated new born is necessary
• Lung function improves within 7- 10 days.
• Pt not improve an ECMO or with all the resuscitation X 3 wks have bad prognosis

Pre – operative Management

• Assessment of associated anomalies.
• Maintenance of Normothermia , environmental 30- 40 c.
• ABC, CBC , sr. electrolytes ,blood sugar, blood grooping and cross matching
• Venous access secured in upper limb, central various line through femoral or umbilical vein. Neck veins preserved for ECMO .
• Use of vasodilators – tolazoline , NO ,Prostacyclin , dipyridamole to decrese pulmonary  HTN .
• Minimize sympathetic discharge by high dose opioids.
• Nasogastric suction for gastric decompression.
• Transport to OT with O2 supplementation or ET tube in place with manual ventilation.

Anesthetic Consideration

• Infant in semi – sitting position warmed with warming device , humidified inspired gases & warmed fluid at 37’c .
• Pre –oxygenation with 100 % O2
• Pre – medication with atropine 20 µg/ kg
• High dose opioid to decrees sympathetic discharge
• Awake intubation can be doe
• Alternatively halothane/ sevoflurone with O2 on spontaneous ventilation , N2o avoided to avoid resp. embarrassment
• Bag – mark ventilation & resp. Gastric distention & resp. embarrassment.
• Gental hand ventilation is preferred to avoid ipsilateral or contralateral is preumothorax.
• Anaesthesia is maintained with 100 % O2 with volatile agent and fentanil 1-3 µg/kg
• in shock is maintained on O2 supplementation & non depolarizing muscle relaxants.
• Inhalational agent, opioids and NMB’s are added in titrated doses.
• Pancuronioum, Vecuronium Or Atracunium can be used.

Ventilation

• Low pressure < 20 mm Hg & high RR 60- 120/ min to achieve hypocarbia & keep the Ph between 7.55 -7.60 & maintain PaCo2 between 25-30 mm Hg .

Management of pul HTN

Factor causing  in PvR

• Deficiency of surfactant
• Hypercarbia
• Hypoxia
• Acidosis
• Stress
• Ventilator induced lung injury
• Flutuating pulmonary blood volume.

Treatment

I. Continue ventilation in the ICU with fentanyl 3µg/kg ,pancuronium 0.1 mg /kg/hr to blunt autonomic cardiovascular response.
II. Minimize endotracheal suction to avoid hypoxia
III. Hyperventilate with low tidal volume, high RR to maintain hypocarbia & Ph 7.55- 7.60 to decrease PVR
IV. Restrict fluid 2-4 ml/kg/hr.
V. Administer pharmacologic pulmonary vasodilator like morphine, chlopromazine, PGE, Inhaled NO
VI. Sever pulmonary hypoplasia with refractory pulmonary HTN with arterial O2 saturation < 50mmHg with fio2 needs ECMO therapy
VIII. High frequency oscillatory ventilation to improved ventilation.

Fluid Replacement

• Correction of pre – op deficit.
• Maintenance fluid with 1/2 strength Ns + 5% D 4ml/ kg/hr.
• Intra-op & 3^rd space loss replaced with RV or saline 6-8 ml/kg/hr.
• Blood loss replaced with 3 ml of crystalloid, 1 ml of 5 % Albumin / 1 ml of whole blood or 0.5 ml of RBC for each ml of loss.

Post –op Management

• Decision of Post- op ventilation should be taken electively.
• FiO2 adjusted to maintain Po2 150mm Hg.
• Child is weaned off slowly 48- 72 hrs to avoid the honeymoon phase i.e. . Early smooth course followed by development of pulmonary Vasoconstriction & lethal persistent pulmonary HTN , hypercarbia & acidosis
• Do not extubate the child till the child is fully awake, maintaining saturation of 100% & rhythmically open the eyes.

Mortality Depends Upon

• Reappearance of fetal circulation
• Pulmonary Hypoplasia
• Associated congenital anomalies.
• Pre –op Preparation
• Shock