Anaesthesia for repair of congenital diaphragmatic hernia
By
Prof. Dr. Adel Rizk Botros The head of department of anaesthesia and Surgical ICU. Faculty of Medicine - Zagazig University.
Contents of this talk: - Introduction about CDH.. - Incidence of CDH. - Classification of CDH - Pathophysiology of CDH. - Clinical presentation of CDH. - Approaches for surgical repair of CDH - Anaesthetic problems of surgical repair of CDH. - Anaesthetic management of CDH. - Conclusion.
Introduction: - Congenital Diaphragmatic Hernia (CDH) is a herniation of abdominal contents into thoracic cavity through congenital defect in diaphragm. - It is a life threatening condition that needs general anesthesia for surgical correction either immediately after birth or immediately after stabilization of the child breathing or heart function and rarely in utero. - Because it is associated with many anaesthetic problems it is considered a difficult challenge to anaesthetist.
Incidence: - CDH occurs in 1 in every 2,000 - 5,000 live births world wide. - It accounts for 8% of all major congenital anomalies. - Approximately 50% of babies with CDH have another congenital anomalies, some of them may be life threatening. - Approximately 5 - 16 % of babies with CDH have a chromosomal abnormality such as trisomy 21 (Down syndrome).
Classification: - According to the anatomic location of the defect, CDHs are classified into the following: 1- Posterior lateral CDH (Bochdalek’s henia): Anatomic location of - It is of 2 types: - Right: It is represents about 10% of all cases. - Left: It is represents about 90% of all cases. 2- Anterior DH(Morgagni’s hernia): - It is about 2% of all cases.
the various CDH
3- Para esophageal CDH. 4- Diaphragmatic eventration: - It is partial or diffuse thinning of diaphragm that allows abdominal viscera to protrude upwards through thoracic cavity.
Diaphragmatic eventration:
Pathophysiology: - Lung and heart compression by the herniated abdominal viscera during gestation leads to the following changes: 1- Ipsilateral pulmonary hypoplasia i.e. immature lung with subsequent inadequate gas exchange. 2- Increase of PVR with subsequent pulmonary hypertension. 3- Contralateral atelectasis i.e. collapse of part or whole lung. 4- Acidosis: Respiratory acidosis due to hypercarbia as the result of to hypoplesia and atelectasis. Metabolic acidosis : due to hypoxia with subsequent lactic acidosis. 5- Persistent fetal circulation due to hypoxia, hypercarbia and acidosis.
Clinical presentation: Classic Triad: - Cyanosis. - Dyspnea. - Displaced apex beat to contra-lateral chest side.
Physical Exam: - Scaphoid abdomen and barrel chest. - Decreased or absent breath sounds on the ipsilateral chest side. - Bowel sounds in the ipsilateral chest side. - A shift of the mediastinum and its contents to the contra-lateral chest side. Chest X ray: - Loops of bowel in the ipsilateral chest side. - Mediastinal shift to contra-lateral chest side.
Note the scaphoid abdomen. This occurs if significant visceral herniation into the chest is present.
Clinical presentation of CDH (Cont.):
Associated congenital anomalies with CDH: Cardiovascular defects as VSD. CNS defects as myelomeningocele, encephalocele, etc. Genitourinary anomalies. Esophageal atresia . Omphalocoele. Down syndrome.
Approaches for surgical repair
of CDH: A- Invasive or open surgery:
Laparotomy
- Laparotomy. - Thoracotomy. B- Non-invasive surgery: - Laparoscopic repair. - Thoracoscopic repair.
laparoscopic repair of CDH
Thoracoscopic repair of CDH
Anaesthetic problems of surgical repair of CDH: A- Specific problems of neonates: - Anatomical problems : as difficult veins and difficult airway etc. - Physiological problems : as high metabolic rate, limited pulmonary, cardiac and thermoregulatory reserve and impaired renal and hepatic function. - Pharmacological problems: as differences in drug response due to multi-system immaturity when compared to the older child or adult.
B- Specific problems of prematurity (less than 37 weeks gestation) as more liability to: - Perioperative hypoglycemia. - Apnoea. - Congestive heart failure. - Intracranial haemorrhage.
- Hypothermia. - Respiratory distress. - Retinopathy.
Anaesthetic problems of surgical repair of CDH (Cont.):
C- Specific problems related to the pathophysiology of CDH as: 1- Problems related to pulmonary hypoplasisa: - Acidosis. - Hypoxaemia, - Hypercarbia. - Pulmonary hypertension. - Liability to barotraume during MV.
3- Problems related to persistent fetal circulation (PDA): RT to LT shunt. 4- Problems related to dehydration. 5- Problems related to shock. 6- Problems related to the associated anomalies: - Cardiovascular defects as VSD with Lt- Rt shunt. - CNS defect: myelomeningocele, encephalocele, etc - Genitourinary anomalies. - Esophageal atresia. - Omphalocoele. - Down's syndrome: Difficult airway, Atlanto-axial instability etc. - Cleft lip: Difficult airway. 7- higher mortality (40-50%) because of severe underdevelopment of the lungs.
Anaesthetic problems of surgical repair of CDH (Cont.):
D- Specific problems of the selected surgical procedure: - Specific problem of thoracotomy & thoracoscopy: 1- One lung ventilation: hypoxia and hypercarbia. 2- Lateral decubitus position: V/Q mismatch. 3- Vagal response to tracheal manipulation:brochospasm, brochospasm, bradycardia, hypotention etc. 4- Pulmonary shunting: hypoxia and hypercarbia. 5- Systemic hypotension caused by kinking of major blood vessels, particularly those of the liver. 6- Contra-lateral pneumothorax: hypoxia and hypercarbia.
Anaesthetic problems of surgical repair of CDH (Cont.):
- Specific problems of laparoscopy as: - Increase intra-abdominal pressure: gastric regurgitation and aspiration etc. - Stretching of peritoneum: bradycardia and bronchospasm. - Intraperitoneal CO2: local irritation or hypercarbia. - Trocar insertion which may lead to visceral injury.
- Specific problems of open surgery as: - Inability to difficult closure of the abdomen. - Abdominal compartmental syndrome. - Blood loss.
Anaesthetic management: Preoperative management: I- Preoperative assessment of general condition:
History: - Gestational age and birth weight. - Polyhydramnios (predictor of poor diagnosis). - Onset of symptoms (dyspenea) after birth.
Preoperative assessment of general condition (Cont.):
Physical examination: Skin colure: - Cyanosis. Chest: - Dyspenea. - Barrel shape. - Decrease breath sound in ipsilateral side. - Bowel sounds in ipsilateral side Heart: - Tachycardia - Shift of the cardiac apex to other side. - Murmurs if cardiac defect is associated. Abdomen: - Scaphoid shape. Sings of the other associated anomalies as Down syndrome (microcephaly, big tongue, upward slanting eyes, single crease in the palm of the hand etc.).
Preoperative assessment of general condition (Cont.):
Investigations: Laboratory Studies: - CBC. - Serum electrolytes levels. - Blood type and cross-match.
Chest X ray: - Loops of bowel in the chest. - Mediastinal shift. CT & MRI: - Defect in the diaphragm. - Compressed fetal lung. - Intestinal loops in the thorax.
Cardiac Echo: - To exclude CHD. - To assess RV function. - To estimates PA pressure.
- ABG. - Blood glucose level.
Preoperative management (Cont.):
II- Preoperative assessment of prognosis: - It is by assessment of the degree of pulmonary hypoplasia: - Severe bilateral hypoplasia is associated with high MR (80%). A-a PO2 gradient is more than 500mmHg is predictive of unsurvival. - Unilateral hypoplasia – the patient may survive with aggressive treatment.. A-a PO2 gradient is 400-500mmHg is predictive to uncertain prognosis. - Insignificant hypoplasia is associated with low mortality rate (20%) – good prognosis. A-a PO2 gradient is less than 400 mmHg is predictive of survival.
Preoperative management (Cont.):
III- Diagnosis the site shunt in persistent fetal circulation i.e. (ductus arteriosus and foramen oval):
- It is performed by: 1- The difference between Pre and post ductal PaO2: - If shunting occurs via ductus arteriosus: preductal PaO2 is more than postductal by 20-30mmHg. - If shunting occurs via foramen ovale: preductal PaO2 is less that predected for 20% shunting (which is normal). 2- Cardiac catheterization. 3- Pulmonary angiography.
Preoperative management (Cont.):
Preparation: - Allows stabilization of the infant before surgical repair. - Decompress stomach by insertion of NGT. - Correction of hypoxia, hypercarbia and respiratory acidosis by: - ETT intubation and mechanical ventilation with low inflating pressures to avoid pulmonary barotrauma.
- HFO reduces PA pressures and resistance resulting in better oxygenation. - Decrease Rt to Lt shunt by reduction of pulmonary HTN and increasing of systemic BP. - Extracorporeal membrane oxygenation (ECMO).
Preparation (Cont.):
- Reversal of persistent pulmonary hypertension (PPH) to avoid right to left shunting through the patent foramen ovale and/or ductus arteriosus by: - Correction of metabolic acidosis by NaHCO3. - Moderate respiratory alkalosis. - Inhaled Nitric oxide (via nasal or face mask): It is effective in PPHTN. - Prevention of pain: - Fentanyl infusion 3-10 mcg/kg/hr. - Avoid hypothermia.
Preparation (Cont.):
- Correction of dehydration by optimum doses of crystalloids (10 - 15ml/kg/hr boluses). - Correction of shock in severe cases by fluid and inotropes as dopamine/dobutamine to maintain BP at around 50mmHg. - Correction of hypoglycemia (if blood glucose level is less than 45 mg/dL). - Avoid hypothermia.
Pre-medication: - Sedatives are not needed. - Anticholinergics: - Atropine: 0.02 mg/kg IM, PO. - Scopolamine: 0.02 mg/kg IM. - Glycopyrrolate: 0.01 mg/kg IV, IM.
Intra-operative management : IV access. Induction& intubation (if not previously intubated): a- In laparotomy or laparoscopy: - Preoxygenation. - Awake endotracheal intubation with non cuffed ETT. - Inhalational induction (Halothane or sevoflurane + 100% O2) is used for endotracheal intubation in too vigorous neonates. NB: - Avoid mask ventilation or PPV before intubation to prevent overdistension of the intrathoracic stomach which will further compromise the hypoplastic lungs and respiration. - Keep neck in neutral position to avoid cervical dislocation if Down syndrome is associated.
Intra-operative management (Cont):
b- In thoracotomy or thoracoscopy: - Preoxygenation. - Awake mainstem endobronchial intubation with a conventional single-lumen ETT. - Inhalational induction (Halothane or sevoflurane + 100% O2) is used for contralateral mainstem endobronchial intubation with a conventional single-lumen ETT. in too vigorous neonates. NB: - A fiberoptic bronchoscope (FOB) can be passed through the ETT to confirm or guide its placement. - Avoid mask ventilation or PPV before intubation to prevent over-distension of the intrathoracic stomach which will further compromise the hypoplastic lungs and respiration. - Keep neck in neutral position to avoid cervical dislocation if Down syndrome is associated.
Intra-operative management (Cont):
Maintenance: Surgical Position: - Supine position in laparoscopy or laparotomy. - Lateral position in thoracoscopy or thoracotomy. Drugs: - O2/air + Halothane or sevoflurane + fentanyl (1 ug/kg) + MR (atracurium 0.5mg/kg). NB: - Avoid Nitrous Oxide to avoid: - Hypoxemia. - Air expansion in bowel which leads to: - Further lung compression. - Increase the IAP with subsequent abdominal compartmental syndrome.
Intra-operative management (Cont):
Ventilation: Methods:
Controlled ventilation: - Bilateral Lung Ventilation. - Single-Lung Ventilation.
Objective : - Peak Inspiratory Pressure (PIP) < 25 cm H2O. - Preductal SpO2 >90%.
Intra-operative management (Cont):
Monitoring: - ECG. - BP: Intra-arterial monitoring. - SpO2: 2 pulse oximeters (preductal and postductal) i.e. in Rt hand and in one foot to estimate the severity of extrapulmonary R-L shunting. - Precordial stethoscope. - AB gases from preductal artery e.g. RT radial or Rt temporal artery. - ETCO2 and volatile agent. - Airway pressure. - Core temperature: Oesophageal and rectal temperature. - CVP: To monitor intravascular volume. - Foley catheter: To monitor urine output and to monitor IAP.
Intra-operative management (Cont):
Fluids: Aim: - To replace intraoperative loss + Daily requirement Type of fluids: Isotonic solutions as: Crystalloids– D5% in 0.2% NS or Saline/ Hartmann solution. Colloids. Whole blood or its products as PRBC, Platelets and FFP or Cryoprecipitate.
Volume: - Isotonic solutions: Boluses of 10-20ml/kg/h and assess clinically – HR, BP, capillary refill, base excess, Hb. Warmed blood: Should be transfused to maintain the Hb at approx 10-12 g/dl: (4ml/kg PRBC.s raises the Hb by 1g/dl) or when 10% blood loss has occurred, guided by weighing swabs etc and clinical parameters. - Platelets and FFP are given in 10ml/kg aliquots if the platelet count or coagulation screen is abnormal. - Cryoprecipitate is transfused in 5ml/kg aliquots if the fibrinogen levels are low.
Intra-operative management (Cont):
Avoid hypothermia: - Hypothermia if not avoided it may lead to:
- Cerebral and cardiac depression. - Increased oxygen demand. - Acidosis. - Hypoxia. - Intracardiac shunt reversal.
Measures to avoid hypothermia: - Heating blanket. - Increase room temp. - Plastic wrap. - Fluid warmer.
Intra-operative management (Cont):
Early detection and management of intra-operative acute episode of pulmonary hypertension:
Diagnosis: - Increase in Rt - Lt shunt i.e. increased gap between SpO2 of
right hand and foot. - ECG : RT side strain (ST depression and T-wave inversionin inV1-4). - ECHO: Reduced LV diastolic volume. TT:
a- Prophylactic measures: -Avoid factors that increase PVR which in turn lead to Rt→Lt shunting as: - Hypoxia. - Acidosis. - Hypothermia. - Pain.
Intra-operative acute episode of pulmonary hypertension (Cont.):
b- Curative measures : a- Analgesic: fentanyl (1-3ug/kg/h). b- Hyperventilation to improve oxygenation and reduce PCO2. c- Moderate restrict of fluid to 2 to 4ml/kg/h. d- Pharmacologic therapy (Vasodilators): - Tolazoline this is the accepted medication to reduce pulmonary hypertension. - Nitric Oxide (NO) this specifically dilates the pulmonary blood vessels and it is given through endotracheal tube.
Intra-operative management (Cont):
Early detection and management of hypotension: Causes: - Venous return impairment. - Hypovolemia. Management: - Fluids /or inotropic support.
Intra-operative management (Cont):
Early detection and management of contra-lateral pneumothorax: Diagnosis: - A sudden fall in lung compliance. - A drop in blood pressure. - A drop in O2 Saturation.
TT: - Immediate placement of a chest tube.
Intra-operative management (Cont):
Recovery: - Some babies with small defects can breathe spontaneously immediately after surgery. but - The majority require prolonged post operative ventilation due to the increased intra-abdominal pressure with compromised respiratory function.
Criteria of extubation: - Neonates should only be extubated when they are: - Fully awake. - With regular spontaneous breathing. - With vigorous movements of all limbs. - Well saturated. - With stable haemodynamics.
- All neonates that are able to be extubated should be reversed with neostigmine (50mcg/kg) and atropine (25mcg/kg).
Postoperative Care: Site: In Neonatal Intensive Care Unit (NICU) because most of patients are critically ill at the conclusion of surgical repair of CDH .
Close monitoring of vital signs. The baby position: Semi-upright position. Nasal or face mask O2 administration: FiO2 is adjusted to maintain PaO2 more than 150mmHg and the infant is slowly weaned from O2 over 48-72 hours to avoid the honyemoon phenomenon.
Postoperative Care: (Cot.):
MV: CMV or HFOV It is indicated if nasal or face mask O2 administration is not enough to deliver adequate oxygen to the patient. The goal is maintaining hypocarbia and a pH greater than 7.5
ECMO: It is indicated if MV is not enough to deliver adequate oxygen to the patient.
ECMO for oxygenation of markedly hypoxic baby in ICU .
Postoperative Care: (Cot.):
Patient warming. Providing analgesia: - Oral sucrose in a variety of concentrations (up to 24%) with or without dummy (non-nutritive sucking). - NSAID. - Opioids. - LA etc.
Control of hypoglycemia. Control of intravascular volume status. Correction of rebound or persistent pulmonary hypertension (PPHN) that may develop after the postoperative Honeymoon Period (period of rapid improvement that followed by rapid deterioration).
Conclusion: - Anaesthetic management of patients with CDH poses a significant challenge to anesthesiologists especially juniors. - Understanding of the related pathophysiology, clinical picture, anaesthetic problems and the specific considerations for perioperative anaesthetic management are important for proper management of such cases with subsequent better outcome.
Thank you