Case 60 - congential diaphragamtic hernia Flashcards
Describe the pathophysiology of congenital diaphragamtic hernia
- occurs during fetal development
- posterolateral diaphragm defect on the Left side = most common site
- abdominal contents hernia into pleural cavity –> impair lung development –> pulmonary hypoplasia
-
although ipsilateral side is primarily affected, contralateral lung also is abnormal:
- decreae number of bronchi and alveoli
- inappropriate muscularized pulm arteries
Physiologic changes
-
increase in PVR and persistent pulm HTN
- persistent pulm HTN –> patent foramen ovale and ductus arteriosus –> hypoxia and acidosis –> further leads to patent ductus arteriosus (closes only with increase PaO2)
is congenital diaphramatic hernia an emergent surgery?
No
- may be associated with congenital anomalies (CVS, GI, GU, craniofacial)
Initial managment
- intubate
- improve ventilation and oxygenation
- once stabilized, perform surgery
What are the clinical features of CHD?
pathophys review
- herniation of abdominal contents into thorax causing hypoplastic lungs.
- hypoplastic lungs –> increase PVR –> persistent pulm HTN of newborn –> patent ductus arteriosus and foramen ovale –> hypoxia and acidosis (becuase reduced blood flow to lungs)
Clinical features:
- tachypnea
- cyanosis
- scaphoid abdomen
- absence of breath sounds on affected sides
- heart sounds shifted to contralateral side
how is CHD diagnosed?
In utero
- ultrasonography may show disease
Post-natally
- CXR –> definitive diagnosis –> abdominal contents in thoracic cavity
What is the preop managment of a neonate with CHD?
1) AVOID bag mask ventilation
* can cause distension of abdominal organs in thorax –> compress the lungs further –> prevent futher oxygenation and ventilation
2) Tracheal intubation
3) maintain insp pressure < 40 cm H2O
-
at risk for pneumothorax of contralateral lung
- contralateral lung affected 2/2 gas flow to path of least resistance = contralateral lung
4) insert OG tube
* decompress stomach to avoid compression of lungs
5) transfer to NICU for sabilization
What is the pulmonary goals for CHD patients?
AVOID INCREASES IN PVR
factors that increase PVR
- Hypoxia
- hypercarbia
- acidosis
- hypothermia
- sympathetic stimulation
Other ways to decrease PVR
- inhaled nitric oxide
- pulmonary vasodilators
- avoid volume overload and subsequent pulm edema
- ECMO
What is permissive hypercapnia? How may this be beneficial to CHD patients?
Permissive hypercapnia
- Allow PaCo2 to increase, while maintaing adequate oxygneation and acid-base balance.
- PaCO2 can lead to resp acidosis, but you can correct pH with other measures like bicarb or THAM solution
permissive hypercapnia and CDH pts
- goal is to avoid increase in PVR.
- in order to decrease PaCo2, higher inspiratory pressure required to maintain ventilation –> result is barotrauma / risk of pneumothorax
- in permissive hypercapnia, allow PaCo2 to increase, but maintain normal acid-base balance with bicarb and THAM.
- maintain pre-ductal SaO2 > 90%
What are the anestheic considerations for neonates with CDH?
1) Avoid increases in PVR
- hypoxia, hypercarbia, acidosis, hypothermia, symp stimulation = all increase PVR
- adequate oxygenation
-
hyperventilation
- continue permissive hypercapnia if employed pre-operatively
- keep an eye on peak insp press if hyperventilating
-
Alkalosis
- serial ABGs
- Normothermia
2) Avoid increases in peak inspiratory pressure
- may need higher peak inspiratory pressure to maintain adequate ventilation and oxygenatoin
- places lungs at risk for barotrauma and pneumothorax (contralateral lung more affected)
- consider decrease TV and increase RR –> may decrease inspiratory pressures
3) continue pharmacologic infusions (NO, pulm vasodilat)
4) avoid N20
* can cause intestinal distension –> impede abd closure
All of a sudden, the blood pressure starts to decrease, and neonate is progressively becoming unstable and deteroriating. What is the most likley cuaes, what do you do?
- avoid high peak inspiratory pressure > 40 cm h2o
- if neone suddenly beocmes unstable, think pneumothorax of contralateral lung
- needle decompression
- followed by chest tube insertion
Would you extubate the neonate after surgery?
NO
- despite surgery fixing the defect, the PVR is not going to be normalied immedietly
- pulm HTN may persist, and neonates will require oxygen and ventilatory support
- the neonate still has pulmonary hypoplasia that will not change immedietly with surgery