Keywords vein of Galen malformations - mechanical ventilation - noninvasive ventilation
Introduction
Patients with vein of Galen malformations (VOGMs) usually present with neurological
manifestations and occasionally with severe cardiac failure, and management of these
patients can be challenging, especially in the neonatal period.[1 ] We report the management of a neonate with VOGM in cardiac failure who needed emergency
therapeutic intervention within the first 10 days of life after obtaining informed
consent from the parents. Post intervention, the neonate was refractory to multiple
attempts of conventional weaning from mechanical ventilation and was successfully
weaned using a noninvasive ventilation (NIV) bridging therapy.
Case Report
A term neonate weighing 2.6 kg delivered by cesarean section for failed induction
presented with respiratory and severe cardiac failure after birth and was intubated
and mechanically ventilated. Chest X-ray revealed cardiomegaly ([Fig. 1 ]). Two-dimensional echocardiography showed severe pulmonary arterial hypertension,
dilated right atrium, and right ventricle with biventricular systolic dysfunction.
A neurosonogram demonstrated features suggestive of VOGM and the neonate was referred
to our institute for further management. On systemic examination, the neonate had
a hyperdynamic precordium with a pansystolic murmur in the mitral area, hepatomegaly,
and loud continuous bruit audible all over the cranial vault. Despite initiating the
medical management, that is, injections of milrinone (0.5 μg/kg/min), isoprenaline
(0.05 μg/kg/min), prostaglandin E1 (0.05 μg/kg/min), and furosemide (1 mg/kg) BD,
we were unsuccessful in controlling the high-output cardiac failure.
Fig. 1 Chest X-ray of the neonate showing cardiomegaly.
Emergency embolization of the VOGM was undertaken to improve the cardiac function.
Intraprocedural management was according to our institutional protocol. Anesthesia
was maintained with end-tidal sevoflurane (1.5%), air:oxygen (50:50), and fentanyl
(1 μg/kg/h) and atracurium (0.3–0.5 mg/kg/h) injections. During the procedure, the
heart rate was maintained at 140 to 160 bpm, pulse oximetry was 98 to 99%, end-tidal
carbon dioxide at 30 to 35 mm Hg, and the partial pressure of carbon dioxide in arterial
blood [PaCO2 ] at 35 to 40 mm Hg. Forced-air warming system was used to maintain normothermia and
arterial blood pressure was maintained in the range of 60/40 mm Hg throughout the
procedure with a titrated injection of milrinone infusion (0.5 μg/kg/min) on flow.
Partial embolization of VOGM was done, wherein two out of three feeding arteries were
occluded ([Fig. 2 ]) and the neonate was shifted to intensive care unit for further management and kept
on sedation with fentanyl (1 μg/kg/h).
Fig. 2 Digital subtraction angiography of the brain shows the embolization of vein of Galen
malformation (arrow).
Post embolization, echocardiography revealed improved biventricular function with
persisting pulmonary hypertension and patient was extubated after 2 days. However,
the neonate required reintubation in view of persistent hypercarbia and was taken
up for follow-up angiogram and complete embolization. Postprocedure injections of
noradrenaline (0.01–0.05 μg/kg/min) and milrinone (0.5 μg/kg/min) were used to maintain
the blood pressure. Despite improvement in the hemodynamic profile, patient failed
repeated extubation attempts and continued to require ventilator support in view of
persistent hypercarbia (the partial pressure of carbon dioxide [PCO2 ] > 80). Therefore, decision was taken to give a trial extubation followed by NIV
bridging support to maintain effective breathing. Nasal continuous positive airway
pressure (NCPAP) was used with nasopharyngeal airway with fraction of inspired oxygen
(FiO2 ) of 0.5, peak end expiratory pressure (PEEP) of 5, respiratory rate 30, and pressure
control of 8 cm H2 O. The neonate was on CPAP for 2 days that was gradually weaned and discontinued and
was shifted to the ward on day 4 and subsequently discharged from hospital.
Discussion
Neonatal cardiac manifestations of VOGM can range from asymptomatic cardiomegaly to
severe high-output cardiac failure and pulmonary hypertension.[2 ]
[3 ] Our patient had severe biventricular dysfunction and severe cardiac failure as 60
to 80% of the aortic blood flow was getting diverted through the low-resistance cerebral
arteriovenous shunt. In our case, as the cardiac dysfunction was not responding to
medical management, the patient was taken for emergency neurointervention for embolization
of the defect. Post procedure, our patient was refractory to weaning attempts mostly
due to the pre-existing poor biventricular function and persistent pulmonary hypertension
that led to oxygenation and ventilation defect. Our patient failed multiple weaning
attempts; thus, we initiated NIV via a nasopharyngeal interface and successfully weaned
the patient. In our scenario, it facilitated successful extubation and weaning by
improving the cardiac function and limiting the adverse effects of hypoventilation,
apnea, and postextubation atelectasis.
The initial goal of therapy in patients with VOGM presenting with failure is to arrest
the congestive cardiac failure rather than to achieve complete obliteration of the
arteriovenous shunt. The cardiac status transiently worsens in these patients after
embolization because of sudden afterload placed on left ventricle by the closure of
the low resistance, high-flow VOGM and also due to the fluid overload caused by the
neurointervention procedure.[3 ] Total or near total obliteration of VOGM is avoided in single sitting because it
can worsen the cardiac failure due to an acute increase in after-load caused by the
removal of the low-resistance shunt. All this could attribute to difficulty in weaning
and extubation of these subsets of patients in the postprocedural period.
Noninvasive ventilation in neonates has been attempted to maintain effective oxygenation
and ventilation.[4 ]
[5 ]
[6 ] NIV helps to maintain functional residual capacity (FRC) in neonates by augmenting
their spontaneous respiratory effort and minute ventilation.[5 ]
[6 ] Lung volume also influences the lung compliance in neonates, that is, smaller the
lung volumes, smaller their compliance. The application of NCPAP helps in increasing
the FRC, thereby improving the gas exchange resulting in better oxygenation and ventilation.[6 ]
[7 ] It is equivalent to PEEP provided through conventional ventilator without the associated
adverse effects of invasive mechanical ventilation. The NCPAP has been found to be
efficacious in successful weaning when used at 5 cm H2 O especially when extubation is performed within the first 14 days of life.[7 ] Nasal and nasopharyngeal interfaces have been shown to be most effective, generate
least amount of airway resistance, and are minimally invasive.[7 ]
Noninvasive ventilation should be used cautiously in neonates, because if the NCPAP
pressure is too high, it can result in ventilation perfusion mismatch with increasing
PaCO2 levels due to the hyperinflated lungs. Similarly, if low-pressure NCPAP is used,
it will result in reduced lung volumes and increase in dead space ventilation thereby
causing PaCO2 levels to go up.[7 ] Thus, to get the optimal result with NIV in neonates and to avoid NIV-related catastrophes,
a protocol-based NIV therapy should be practiced. Studies have shown that an initial
CPAP of 6 cm H2 O and an incremental increase by 2 cm H2 O resulted in best clinical outcomes. An initial flow of 8 to 12 L/min is optimal
as a high flow reduces the work of breathing (WOB), leading to a greater stability
of blood pressure. Initial FiO2 should to titrated to maintain PaO2 values between 50 and 60 mm Hg and oxygen saturation levels between 90 and 95% to
avoid retinopathy of prematurity.[7 ] Weaning failure from NIV can be avoided by reducing the CPAP by 1 cm H2 O with close monitoring for any clinical deterioration. At a CPAP of 4 cm H2 O with stable hemodynamics, the neonate can be safely taken off from NIV.[4 ]
[7 ] Inappropriate weaning will increase the WOB and cause rapid deterioration of respiratory
function, resulting in prolonged ventilator support and convalescence.[6 ]
Conclusion
Weaning of patients with VOGM from mechanical ventilation can be challenging in the
postprocedure period due to underlying high-output cardiac failure and the fluid overload
caused by the neurointervention procedure. NIV can be safely used as a method of weaning,
post mechanical ventilation in this subset of patients. The use of NIV will facilitate
successful weaning and reduce the incidence of extubation failure in neonates with
VOGM in cardiac failure.
Note
The manuscript has been read and approved by all the authors, that the requirements
for authorship as stated earlier in this document have been met, and that each author
believes that the manuscript represents honest work.
