Case Report

Fanuel Ballén*, Maribel Arrieta**

* Estudiante de postgrado de Anestesiología y Reanimación, Universidad Militar Nueva Granada, Bogotá, D.C., Colombia. fanudoc7@hotmail.com.

** Profesora asociada de Anestesiología y Reanimación, Universidad Militar Nueva Granada, Hospital Militar Central, Bogotá, D.C., Colombia.

Recibido: enero 28 de 2010. Enviado para modificaciones: febrero 25 de 2010. Aceptado: marzo 15 de 2010.

Introduction. The Congenital Diaphragmatic Hernia (CDH) is an anatomical structural defect, which allows passage of the abdominal viscera into the chest cavity resulting in morbidity from serious cardiopulmonary complications and high perioperative mortality. In the last few decades new management strategies have been developed that have helped to reduce this high mortality.

Objectives. To review and analyze a clinical CDH case and its perioperative evolution, including a discussion about anesthetic and respiratory management, in addition to reviewing the latest literature on the topic.

Methodology. Presentation of a clinical case

Conclusions. The management of a CDH patient is multidisciplinary. An early diagnosis should be made from the pre-natal period in order to optimize management and make available the best therapeutic tools. However, despite our efforts, mortality is still high.

This is a patient –35 hours after birth– presenting congenital diaphragmatic hernia and at birth was managed at the neonatal intensive care unit with freorotracheal intubation, assisted mechanical ventilation, and inotropic and vasopressor support. Then the patient was taken to the OR to undergo corrective surgery for the diaphragmatic defect. The anesthetic and respiratory management is discussed together with a brief literature review.

Key words: Diaphragmatic hernia, congenital anomalies, surgery, anesthesia (Source: DeCs, BIREME)

CDH is an anatomic defect, which allows passage of the abdominal viscera into the chest, and limits pulmonary and cardiac development. This condition exhibits a high morbi-mortality and occurs in 1 out of every 2 000 to 4 000 newborns, with a strong association to other developmental defects (1). These patients usually develop serious respiratory complications from hypoplasia and pulmonary hypertension. Diagnostic skills, management strategies as well as prenatal and postnatal care have evolved in the last decade; however, the morbid-mortality rates continue to be high.

This is a two-days old female patient diagnosed in uterus with congenital diaphragmatic hernia, pulmonary hypoplasia, interventricular shunt and polyhydramnios. The baby was born preterm –34 weeks of gestation– vaginal delivery from a first pregnancy 21-year old mother with no history of infections. Lung maturation therapy was administered. The Apgar score was 7 at one minute, 8 after 5 minutes and 10 at 10 minutes; birth weight was 2.155 g size 43 cm. The general conditions at birth were average. The pediatrician performed an orotracheal intubation with a No. 3 tube and the patient was transferred to the NICU. The physical examination after her admission to the NICU showed a heart rate of 136 bpm, temperature of 36 ºC, 96 % O₂ saturation, 100 % FiO₂ with SIMW assisted mechanical respiration, a PIP of 26, PEEP of 6, respiratory rate: 50 per minute and inspiratory time 0.38 sec.

The patient exhibited dysmorphic traits such as low set ears, hypertelorism and clinodactilia, triangular face and short neck. The cardiopulmonary auscultation revealed left pulmonary hypoventilation. No cardiac murmurs or cyanosis were detected. An orogastric tube was in place, the abdomen was excavated, particularly on the left side and the liver was 3 cm below the right costal margin. The arterial gases measured from the umbilical cord showed evidence of severe metabolic acidosis and hypoxemia.

The diagnosis at admission was premature infant with adequate body weight for 34 weeks of gestation, with total left diaphragmatic hernia and left pulmonary hypoplasia, congenital heart disease associated with interventricular shunt, high risk of pulmonary hypertension and multiple risks from prematurity.

Initial management included dynamic mechanical ventilation, 7-ml/h dextrose in 10 % distilled water, and dopamine 5 μg/kg per minute, milrinone 0.5 μg/kg per minute, fentanyl 3 μg/kg per hour, plus parenteral nutrition.

The paraclinical exams showed the following values: glycemia, 106 mg/dl, serum calcium 6.6 mg/dl and C-reactive protein (CRP) 0.06 mg/L. The umbilical artery blood gasses indicated: pH 7.10; pCO₂ 56,2 mmHg; PO₂ 6.6 mmHg, HCO₃ 17.2 mEq/l; O₂ saturation 61 % and excess base -12.7. The control readings after intubation were: pH 7.26; pCO₂ 40.2 mmHg; PO₂ 30.1 mmHg; HCO₃ 17.7 mEq/l; O₂ saturation 69.2 % and excess base -8.8.

The results of the blood test were as follows: leucocytes 8 000 per mm³; 36.6 % neutrophils; 52.5 % lymphocytes; hematocrit 38,7 %; hemoglobine 13.5 g/dl and platelets 218 000.

The blood chemistry test indicated a total bilirubin of 9.87 mg/dl; direct 0.39 mg/dl and indirect 9.48 mg/dl.

The chest X-ray showed intestinal loops in the left lung space up to the upper segment, with right mediastinal shift (figure 1).

The echocardiogram indicated a normal cardiac structure, considerable pulmonary hypertension with pulmonary artery systolic pressure (PSAP) of 53 mm of Hg, large persistent ductus arteriosus (PDA) of 2.7 mm, with mostly left-to-right bidirectional shunt. The left ventricular function was preserved and the foramen ovale was oversized.

The renal echography indicated bilateral ectasia of the calyces while the portable transfontanelar echography was within the normal ranges.

The genetic study prompted us to consider either a Frins Syndrome or a Killian-Teschler Nicola Syndrome.

The patient was evaluated through chest surgery and the decision was made to proceed with a surgical correction of the diaphragmatic hernia.

The patient was admitted to the OR on January 18, 2009, with a fixed orotracheal tube at 8.5 cm of the oral commissure, epicutaneous catheter in the right foot and yelco Nº 24 in the upper right limb. The last body weight recorded was 2.9 kg. The patient received a drip infusion of morphine 0.2 mg per hour; 10 μg/kg per minute of dopamine; milrinone 0.3 μg/kg per hour, and parenteral nutrition. Eye, thermal and electrical protection was provided as well as pressure zones protection. When admitted to the OR, the records showed a heart rate of 157 p/min, blood pressure of 56/30 mm de Hg; respiratory rate of 36 p/min and 92 % O₂ saturation.

The ASA score according to the anesthesiologist’s evaluation was IV-E due to the diagnosis of CDH, pulmonary hypoplasia with pulmonary hypertension, dysmorphic syndrome and severe hypoxemia and acidosis.

The fluid balance was estimated at 35 ml p/h, based on 12 ml of base fluids (4 ml/kg of weight) and a loss of 21 ml (7 ml/kg) during the surgical exposure. The patient was under non-invasive blood pressure monitoring, continuous EKG tracing, temperature control, oximetry and capnography.

IV general anesthesia was administered using 4 mg of propofol + 1 mg of rocuronium for induction, and an initial infusion of 20 μg/kg p/h of fentanyl and 0.5 % sevorane. The anesthesia was maintained with 10 μg/kg per hour of fentanyl and 0.5 % sevorane. The continuous administration of vasopressors included 10 μg/ kg p/min of dopamine and 0.3 μg/kg p/min of milrinone.

Pressure-controlled assisted mechanical ventilation was used with a respiratory rate of 35 per minute, max. inspiratory pressure (PImax) of 30 cmH₂O, 6 cmH₂O, tidal volume of 8 ml. At the end of the procedure manual mechanical assisted ventilation was required in response to a hypoxic event.

The surgical procedure performed was a diaphragmatic mesh herniorrhaphy through abdominal approach. The intraoperative finding was a 6 × 3 cm left posterolateral diaphragmatic hernia that contained small bowel, colon, spleen and stomach. There was evidence of 90 % left pulmonary hypoplasia. The surgical time was 1 hour and 35 minutes.

The patient experienced two crisis of hypoxemia, one at her arrival at the OR, prior to induction and the second one at the end of the operation. Both responded to manual assisted ventilation and 3 mg of ephedrine as salvage vasoconstrictor. The CO₂ end expired pressure at the start of the procedure was 55 mmHg and at the end of the surgery was 45 mmHg. Three 3 mg doses of ephedrine were required to treat the hypotension. Intraoperative bleeding was 30 ml and the intraoperative diuresis was 20 ml. Fluid replacement was given with 57 ml of Ringer lactate and 25 ml of gelofusin. Packed red-blood cells were requested for intraoperative transfusion but were delivered at the end of the operation.

By the end of the surgery the patient’s blood pressure was 60/30 mmHg, the heart rate 160 p/min, 90 % O₂ saturation, 45 mmHg and the temperature was 36.4 ºC. The baby was transferred to the pediatric intensive care unit and there were no complications.

After surgery the patient received a 30 ml transfusion of packed red cells. Assisted mechanical ventilation was continued and there was a tendency towards hemodynamic instability, which was treated with dobutamine 10 μg/kg p/min in addition to the inotropic management. The patient continued to deteriorate clinically experiencing hypoxemia and hypotension and died 35 hours later.

Congenital diaphragmatic hernia

The incidence of this condition is 1 per 2 000 - 4 000 life births and accounts for approximately 8 % of the anomalies found in newborn babies. 10 to 50 % of the cases are associated to other defects, including cardiac, neural tube, chromosomal, renal and genital anomalies (1,2). The risk of death from CDH doubles when associated with other anomalies, as compared to the isolated diaphragmatic hernia (3). The overall neonatal mortality associated with this condition is approximately 50 % (2).

Pathophysiology

The condition develops between the third and the eighth week of gestation. 90 % of the cases are on the left side because the pericardium –peritoneal canal is larger on that side and closes later on the right side. To the right, the liver acts as a protective barrier (4). Depending on the size of the defect, the gut occupies the chest cavity involved and may cause bilateral pulmonary hyperplasia. In the case of a left congenital diaphragmatic hernia, about 10 % to 20 % of the normal tissue can be found in the left lung, while 60 % to 70 % can be found in the right lung (5).

The diaphragm is the principal muscle of inspiration and develops towards the end of the third trimester of pregnancy. In CDH neonates the diaphragmatic defect allows the passage of abdominal contents into the chest, hence restricting normal lung development. Pulmonary hypoplasia may compromise not only the lung on the defective side, but also the ipsilateral lung when the herniated intestine shifts the mediastinum and compresses the structures of the non-affected side (6).

Clinical Manifestations

Clinically the abdomen is excavated because of the viscera shifted through de diaphragmatic defect causing varying degrees of respiratory distress and reduced breath sounds in the affected hemithorax (2). In the left CDH, the heartbeat may be heard to the right due to the shifted mediastinum. The seriousness of the respiratory distress and the newborn response to treatment are the best indicators of pulmonary hypoplasia (7).

Usually, the presence of pulmonary hypoplasia together with increased pulmonary pressures and a right to left shunt, determine the occurrence of hypoxia and acidosis.

The etiology of CDH is unknown. However, its origin is considered multifactorial and genetic factors may play an important role. The diaphragmatic defect is mainly due to fusion anomalies of poor muscle formation (6).

There are two types of diaphragmatic hernias: the Bochdalek hernia is an anatomic defect in the postero-lateral aspect of the diaphragm and is the most common manifestation of CDH; Morgagni’s hernia is an anterior defect of the diaphragm. The herniated viscera may develop poorly due to decreased blood irrigation (7).

The development of the lungs is limited by structural anomalies due to incomplete septal formation, thickening of the interstitium and fewer capillaries. There are alterations in the quantity and quality of the pulmonary surfactant as well, with a reduced antioxidant response. This pulmonary immaturity translates into respiratory distress at birth and predisposes the baby to develop injuries from the assisted ventilation (3).

The pathophysiology includes: pulmonary hypoplasia, pulmonary hypertension, lung immaturity and potential surfactant and antioxidant enzymes dysfunctions. The poor development of the airway triggered by the viscera occupying the chest, translates into structural defects; there are only 12 to 14 divisions in the airway of the lung involved and up to 16 to 18 in the ipsilateral side. In a normal development lung, the number of airway divisions range from 23 to 35 generations (division of airway branching) (8).

In addition to the poor development of the tracheal- bronchial tree, there are alterations in the development of the arterial system, less arterial branches, muscular hypertrophy and higher sensitivity to vasoconstriction stimuli. All of these changes result in pulmonary hypertension and a pattern of fetal circulation after birth, which intensifies the right to left shunt in the atria and in the arterial canal. This may lead to overload and right cardiac failure, with the typical outcome of hypoxemia, hypercapnia, pulmonary hypertension and acidosis during the neonatal period (1,8).

In addition to pulmonary hypertension, the residual lung parenchyma has less alveoli and undergoes functional disorders that further aggravate the respiratory failure. With breathing, the herniated intestine may fill up with air, increasing the compression to the chest structure, predisposing to the development of atelectasias and intensifying the hypoxemia and hypercapnia, as well as the right to left shunt.

Cardiac anomalies represent around two thirds of the associated anomalies, mainly hypoplastic left heart syndrome, atrial septal defect, ventricular septal defect, coarctation of the aorta and Ebstein’s anomaly. The left ventricle is compromised due to decreased intrauterine blood flow and, less often, due to compression of the hernia causing left ventricular hypoplasia. Furthermore, there is right heart hyperplasia from overload (4,9).

If the condition was not detected prenatally, you should suspect CDH in term newborns with respiratory distress and the absence of breath sounds on the side of the hernia. The diagnosis is confirmed with a chest X-ray.

The ultrasound examination is diagnostic at around 24 weeks of gestation. Usually there will polyhydramnios, absent or intrathoracic stomach bubble, mediastinal and cardiac shift away from the side of the herniation and intestinal loops in the chest that may enter or exit through the herniation (9). The herniated liver may look like a homogeneous mass in the thorax next to the intra-abdominal liver. In the presence of esophageal compression polyhydramnios usually develops while a mediastinal shift and compression of the great vessels causes fetal hydrops (7).

A low maternal serum alpha-fetoprotein may be suspicious for a diagnosis of CDH and should be followed by ultrasound examination. (1).

Upon establishing the diagnosis, any associated chromosomal anomalies have to be ruled out. These occur in 10 % to 20 % of the cases. The most frequently identified are trisomy 13, 18 and 21, 3p microdeletion and tetrasomy 12p (10).

The postnatal diagnosis is confirmed with a chest X-ray at birth, which may show intrathoracic intestinal loops, mediastinal shift, absence of, or decreased intestinal gas and the tip of a nasograstric tube inside the chest. A right-sided herniation requires a differential diagnosis with diaphragmatic eventration and lobe consolidation.

Pre-Anesthesia Evaluation

The pre-anesthesia evaluation must take into account the cardiopulmonary involvement analyzing the acid-base balance, hypoxemia and hypercapnia. The severity of pulmonary hypoplasia is closely related to metabolic acidosis, respiratory distress or both. The evaluation should include: ventricular function, the extent of pulmonary hypertension and the right to left shunt. Every neonate with a diagnosis of CDH should undergo complete radiological, echographic and echocardiographic examinations. (3). The EKG evaluates any associated cardiac anomalies; pulmonary hypertension and the R-L shunt. The presence of pulmonary hypertension, R-L shunt and left ventricular dysfunction calls for comprehensive patient management with inotropics, selective pulmonary vasodilators or both.

Monitoring

The patient should be under continuous cardiac monitoring, urinary output control, blood pressure control, continuous pulsimetry, umbilical artery catheterization and a radial artery line for post and pre-ductal gasometry.

Treatment

Until the 80’s CDH was considered a surgical emergency. At present, the goal is to control the respiratory failure and the pulmonary hypertension before attempting a surgical correction, with a view to stabilize the oxygenation, the blood pressure and the acid-base balance (11,12). This calls for the participation of a multi-disciplinary team involving perinatology, neonatology, pediatric surgery and anesthesiology. Treatment immediately after birth is early endotracheal intubation and assisted ventilation at low volumes to prevent pulmonary hyperinflation and pneumothorax.

It is also important to control the acidosis to decrease the pulmonary vascular resistance. The most serious cases may require extracorporeal membrane oxygenation (ECMO) (13). Survival rates have improved over the last two decades up to 60 % - 80 %, focusing the initial management on optimizing and stabilizing the respiratory function before surgery.

Once pulmonary stability is achieved, the surgical intervention has to be assessed and planned for.

The optimal time for surgery depends on the severity of the clinical condition. Patients with mild symptoms, no pulmonary hypertension or vascular impairment may be taken to surgery 48 to 72 hours after birth. Patients with mild pulmonary hypoplasia and reversible pulmonary hypertension may undergo surgery after resolution of the pulmonary hypertension and improvement of the lung compliance, usually after 5 – 10 days. Patients with pulmonary hypoplasia and pulmonary hypertension do not respond to any therapy, not even ECMO. The defect can be so serious that it is incompatible with life (7).

Surgical care is based on the reduction of the herniated viscera and closure of the diaphragmatic defect with sutures or, depending on the size, placement of a patch or an abdominal wall flap. The survival rates for patients managed with pre-surgical stabilization and appropriate ECMO, ranges between 79 % and 92 % (12).

There are intrauterine strategies aimed at improving the development of the lungs before birth. One of these strategies is the fetoscopic pulmonary occlusion that stimulates the proliferation of the distal airway and improves the prognosis in these patients. However there are risks involved such as premature membrane disruption and pre-term delivery (14,15).

Excessive hyperventilation should be avoided in the post-natal period. The actual recommendation is “gentle ventilation” as described by Wung et al. back in 1995, aiming at the lowest airway pressure, with peak inspiratory pressures < 25 cm of H2O, improving the venous return and reducing the risk of barotrauma (14,15).

The newborn must be intubated immediately after birth, avoiding a facemask positive pressure during pre-oxygenation, which causes gastric distension and worsens the pulmonary compression. The stomach has to be decompressed using a continuous suction nasogastric tube. Catheterization of the umbilical artery is important to take samples for arterial gases and measure the continuous blood pressure, in addition to administering fluids and drugs. The mean blood pressure should be kept above 50mm Hg to reduce the right to left shunt. This goal is achieved with a conscientious input of isotonic fluids, and if needed, administering inotropic agents such as dopamine and dobutamine.

Ventilation. The goal is to maintain the preductal oxygen saturation above 80 %, or a partial oxygen pressure above 60 mmHg (7).

Conventional, pressure-controlled respiratory support is recommended, with a respiratory rate between 30 to 100 breaths per minute, a peak inspiratory pressure between 20 to 25 cm of H2O and physiological PEEP. Permissive hypercapnia has shown to increase survival (12,16). The respiratory support parameters are adjusted according to the arterial gases report and oxygen weaning should be done with extreme care to prevent pulmonary hypertension. The lowest pressures should be used in the airway to achieve oxygen saturation levels > 90 % with PIP values <30 cm of H₂O (17).

High frequency respiratory support is reserved for those patients that fail to respond to the conventional therapy and have persistent hypoxia and hypercapnia. There are some reports of improved survival in these patients with this type of respiratory support (18). It is the first line therapy in some institutions and for patients requiring PIP values >30 cm of H₂O (19).

ECMO is indicated for patients that fail to respond to other treatment strategies and it is a useful approach to reduce the risk of barotrauma and in patients with severe pulmonary hypertension. This latter condition has also benefitted from the use of prostaglandins, milrinone and nitric oxide.

The indications for ECMO are: failure to maintain preductal saturations >85 % or post-ductal PaO₂ >30 %; PIP >28 cm of H₂O or a mean airway pressure >15 cm of H₂O; unresponsive hypotension despite fluid therapy and inotropic support, persistent metabolic acidosis, birth weight above two kg, more than 34 weeks of gestational age, absence of major intracranial hemorrhage (grade I) ad absence of congenital or chromosomal anomalies (20).

In patients with a poor prognosis, the use of pulmonary surfactant at a dose of 50 a 100 mg/kg for the first breath has shown improvements in oxygenation (21). Using nitric oxide for persistent pulmonary hypertension reduces the ventilation/ perfusion imbalance and reverses the shunt in these patients, but its use in patients with CDH and pulmonary hypertension has been limited.

Special considerations about ECMO for Congenital Diaphragmatic Hernia

The Extracorporeal Life Support Organization (ELSO), founded in 1989, has documented over 24 000 patients treated (18 000 neonates, 4 000 pediatric patients and 1 000 adults) (22). The ELSO guidelines define the use of Extra-Corporeal Life Support (ECLS) as the use of mechanical devices to support the cardiopulmonary function (partially or totally) on a temporary basis (days to months) during cardiopulmonary failure, giving some time for recovery of the patient or organ transplant. The Extracorporeal Life Support Registry Report 2004 (23) described survival statistics of 53 % of newborn babies with CDH treated with ECMO. According to the report 2,367 out of CDH 4,491 patients survived after treatment with ECMO.

There are two types of ECMO: venoarterial (VA), that replaces the heart and lung function either partially or totally and venousvenous (VV), when the heart output depend entirely on the function of the native heart.

ECMO is indicated for cardiac or respiratory failure with a high mortality risk, despite optimal conventional therapy (this strategy should be considered for a 50 % mortality risk; it is indicated for patients with a mortality risk > 80 %). ECMO is better when it is administered during the first seven days of mechanical assisted ventilation. It has been helpful in repair surgeries of the tracheal-bronchial tress, mediastinal masses, pulmonary embolism, adult respiratory distress syndrome (ARDS), and fluids overload, sepsis, CDH, meconium aspiration syndrome and persistent pulmonary hypertension of the neonate.

Some contraindications include: lethal chromosomal disorders, conditions incompatible with normal life if the patient recovers, pre-existing conditions that impact the quality of life (CNS status, terminal malignancy, risk of systemic bleeding with anticoagulation), age and size of the patient and patients who are too sick, have been in conventional therapy for too long or have a fatal diagnosis. Intracranial hemorrhage or postsurgical conditions that increase the risk of bleeding (neurosurgery or intracranial procedures; surgery or trauma) are also excluded.

Extracorporeal Circuit

Blood flow for cardiac support. A venous-arterial access with a circuit to support a blood flow of 3 L/m² per minute is required. (Neonates, 100 ml/kg per minute; children, 80 ml/kg per minute; adults, 60 ml/kg per minute), to achieve adequate systemic> 70 %.

Blood flow and gas exchange for respiratory failure. The pulmonary membrane and the blood flow must meet the normal metabolic needs. The recommendation is an oxygen delivery of 6 ml/kg per minute for neonates; 4 to 5 ml/kg per minute for children and 3 ml/kg per minute for adults. This is equal to venousvenous blood flows of 120 ml/kg per minute for neonates and of 60 to 80 ml/kg per minute for adults. If the circuit is partial and programmed only for removing CO₂, the access may be venousvenous, venousarterial or arteriovenous. The blood flow is around 25 % of the cardiac output, enough to remove the CO₂ generated by metabolism.

In neonates with respiratory failure, vascular access is through the neck, with catheterization of the internal jugular artery and the common carotid artery.

The circuit includes a blood pump, a pulmonary membrane, tubes and ducts. The suction pressure should be at least 300 mmHg and la outflow pressure should not exceed 400 mmHg inside the pump. Plasma hemoglobin must be <10 mg/dl. The pulmonary membrane is a porous silicon or polymethyl-pentene membrane and the gas exchange capacity is determined by the flow rate and the maximum oxygen output. The flow rate refers to the venous blood that will be totally saturated when the blood exits the pulmonary membrane. The maximum oxygen output is the volume of oxygen released per minute, calculated as the difference between the oxygen content going in and out of the membrane. These variables determine the type of membrane. It is important to maintain a higher pressure on the arterial side than on the venous side to prevent the development of gas embolism and to keep the pump below the patient’s level.

Crystalloids are added to the circuit. You may also add 12.5 g of albumin to coat the surfaces, red blood cells to raise the hematocrit to 30 % - 40 % values; one unit of heparin per ml of crystalloid and calcium to replace the calcium bound to the citrate of the stored blood. A 50 to 100 μ/kg bolus of heparin is administered to do the catheterization. A heat exchanger should be available.

The blood flow, the blood pressures, the O₂ saturation are all measured before and after the membrane and the blood gases.

During ECMO, special attention should be given to the blood flow (circuit pressures, air, clots), the oxygenation, CO₂ elimination, activated clotting time values and timetable for adjusting the clotting time to 1,5 of the normal during the heparin infusion, the number of platelets and fibrinogen levels.

The ventilator should be managed to allow for pulmonary rest, with low frequencies and extended inspiratory times, low plateau inspiratory pressure (< 25 cm H₂O), low FiO₂ (< 30 %) and PEEP between 5 and 15 cm of H₂O. The ventilator can be managed in the Airway Pressure Release Ventilation (APRV) mode, with positive continuous pressure and occasional pressure relief.

To wean the patient the lowest flow has to be used so as to give adequate support with low respiratory parameters and low doses of vasopressors. You can wean the patient as the organic function improves, having achieved a support of less than 30 %.

The ideal timing to repair a congenital diaphragmatic hernia in patients with extracorporeal membrane oxygenation differs among the various institutions. Experienced surgeons must carry out the procedure, with particular emphasis on hemostasis when anticoagulation is used.

The international registry reports survival rates of 85 % with Extracorporeal Life Support and of 75 % when weaning the neonates form ECMO due to respiratory failure. It is recommended to follow the patients closely to identify any neurological development problems.

Being born and receiving medical care at experienced tertiary care centers apparently improve the odds for survival (12). The mode of delivery of choice for infants with CDH is unknown. In a trial with 548 patients, the survival rates were 71 % in programmed cesarean section, 70 % in induced vaginal delivery and 67 % in spontaneous vaginal delivery, with no significant differences. However, this was not a randomized trial (24).

There are some conditions that seem to impact survival rates in cases of congenital diaphragmatic hernia. These include the intra-aortic position of the liver and the ratio between the cross-section areas of the lung and the thorax (L/T). This ratio can be mild (> 0.13 with 0 % mortality); moderate (between 0.08 and 0.13, with 30 % mortality) or serious (< 0,08, with 100 % mortality when herniation of the liver was present).

From the clinical perspective, respiratory distress in the first six hours after birth reflects a more severe lung involvement and relates to higher mortality rates.

The immediate postoperative therapy includes continuing with assisted mechanical ventilation, treatment of pulmonary hypertension the use of inotropic agents to preserve the hemodynamic stability. It is very important to ensure adequate analgesia and sedation, in addition to the most stringent control of the acid-base balance.

Congenital Diaphragmatic Hernia is a rare disease. Its clinical presentation ranges from mild symptoms to symptoms incompatible with life, depending on the severity of the pulmonary hypoplasia and on concomitant pathologies. Prenatal diagnosis is key to develop a suitable management plan that includes taking care of the patient at a specialized institution and support by a multidisciplinary team.

A comprehensive evaluation should be done in an attempt to identify any cardiopulmonary disorders, hydro-electrolytic and acid-base imbalances that may further aggravate the poor pulmonary function.

One of the main issues related to the management of anesthesia in these patients is ventilation. Depending on the severity of the case, the patient may receive assisted pressure control ventilation , high frequency assisted oscillatory ventilation and extracorporeal membrane oxygenation.

The prognosis of this particular case was gloomy because of a bilateral pulmonary involvement. An interdisciplinary evaluation with the participation of the group of anesthesiologists of the institution from the prenatal stage would have been helpful in planning the postnatal surgical management. Basic monitoring was provided for preventing hypoxic crisis, which in fact occurred twice while the patient was being transferred. These crises were detected and managed promptly. Respiratory management was extremely helpful. We used assisted pressure controlled ventilation in an attempt to secure the lowest possible airway pressures, administering inotropic agents and indodilators (i.e., milrinone, dobutamine) in an effort to maintain hemodynamic stability. The postoperative outcome was consistent with the prognosis.

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