Perioperative Management of a Child with Klippel-Feil Syndrome and Severe Uncorrected Aortic Stenosis Undergoing Cervical Spine Stabilization.

Severe stenotic aortic valve poses serious anesthetic challenges because of the fixed cardiac output and complex hemodynamics. The challenges magnify in the presence of a difficult airway which not only puts the airway at risk but also disturbs the hemodynamics, which can negatively impact the patient outcome. Moreover, prone positioning, intraoperative hemodynamics, recovery, and extubation are equally challenging for management. This case report highlights the perioperative management of a child with severe uncorrected aortic stenosis and Klippel-Feil syndrome posted for cervical spinal stabilization under anesthesia. Copyright:

INTRODUCTION

Severe aortic stenosis (AS) is associated with increased risk of major adverse cardiac events. However, in contemporary practice, perioperative mortality of patients with severe AS is lower than reported previously.[1] Most anesthetics reduce sympathetic tone, leading to a decrease in venous return due to increased capacitance of the venous system, vasodilatation and, finally, hypotension. In the presence of severe valvular stenosis (fixed cardiac output state), hypotension is potentially disastrous as the heart cannot compensate for a decrease in cardiac output. Difficult airway and acute hemodynamic changes during airway management could jeopardize the outcome by placing the cardiovascular system at distress. The prone position can also lead to hypotension that can further complicate the management. Here, we report the management of such a child with severe AS and Klippel–Feil syndrome (KFS) posted for cervical spinal stabilization.

CASE REPORT

A 10-year-old female child weighing 25 kg presented with complaints of abnormal curvature in the back for the last 3 years and difficulty in lateral movements of the neck for 2 years. She also had difficulty in getting up from bed without support and difficulty in walking. The child was diagnosed with KFS with the clinical presentations of a short neck, cervicodorsal scoliosis, and fused cervical vertebra at C5–C7 levels. She had associated platybasia and Chiari malformation with basilar invagination [Figure 1]. Decompression of foramen magnum and posterior cervical fixation was planned under anesthesia in the prone position. The child had a past history of undergoing repair of ventricular septal defect (VSD) at the age of 2 years. The respiratory system examination was unremarkable. Cardiac examination revealed a systolic murmur, and further evaluation with echocardiography showed severe AS with a peak pressure gradient 80 mmHg and aortic valve area 1 cm2 with normal left ventricular function. On airway examination, her Mallampati grade was II and mouth opening was more than three fingers with severely restricted neck movements. Cranial nerve examination revealed the bilateral weakness of trapezius muscles. Sensory system examination revealed reduced touch, temperature, vibration, and proprioception in all four limbs. The tone and bulk of key muscles were normal whereas the power of muscles of all four extremities was of 4/5. Deep tendon reflexes were exaggerated in bilateral biceps, triceps, and knee; extensor response was noticed while eliciting bilateral Babinski reflex. All the laboratory investigations were within normal limits. A chest x-ray revealed an enlarged cardiac silhouette.

Figure 1

Sagittal section noncontrast computed tomography of the base of skull showing dens is more than 2.5 cm above the Chamberlain line (posterior hard palate to opisthion) indicating presence of basilar invagination (A); and atlantoaxial interval more than 10 mm (normal: 5 mm in children) suggestive of atlantoaxial dislocation (B)

In the operating room (OR), prior preparation for difficult airway and possible cardiac arrhythmia (antiarrhythmic medications and cardiac defibrillator) was done; infusions of vasopressors/inotropes were prepared. On arrival of the child to OR, standard monitors such as a 5-lead electrocardiogram (ECG), pulse oximetry (SpO2), and noninvasive blood pressure were applied, and an intravenous (IV) line was secured. Antibiotic prophylaxis was given 60 min before surgical incision. Midazolam 0.5 mg and fentanyl 30 µg slow IV was administered and left radial artery was cannulated after infiltration of 0.5 ml lidocaine. Anesthesia was induced with etomidate 0.3 mg/kg and fentanyl 4 µg/kg. Tracheal intubation was facilitated with rocuronium 0.6 mg/kg using a C-MAC videolaryngoscope (Karl Storz, Tuttlingen, Germany) with a size 2 blade; the head was kept in neutral position along with manual inline stabilization. A 5.5-mm internal diameter cuffed polyvinyl chloride endotracheal tube (ETT) was inserted and fixed at 15 cm at incisors. To avoid any hemodynamic fluctuations, lidocaine 1.5 mg/kg was administered 90 s before intubation. After securing the ETT, anesthesia was maintained with sevoflurane, air–oxygen mixture (50:50) with a fresh gas flow of 2 L/min, and infusion of rocuronium and fentanyl. Mechanical ventilation was adjusted to maintain end-tidal carbon dioxide (EtCO2) of 35–40 mmHg. The right internal jugular vein as cannulated using ultrasound guidance and a 5F triple lumen central line was inserted and secured. Apart from other routine monitors, central venous pressure, nasopharyngeal temperature, and urine output were monitored. Cardiovascular monitoring was done with the FloTrac sensor/Vigileo hemodynamic monitoring system (Edwards Lifesciences, Irvine, CA, USA) and an electrical cardiometry monitor (ICON Cardiotronics, Inc., Osypka Medical GmbH, Berlin, Germany). Cardiac output and stroke volume variation (SVV) were continuously monitored. Then, the child was positioned in prone with adequate care for eyes and pressure points. Goal-directed fluid was administered to keep the SVV below 13%. Blood loss was replaced with an equal amount of blood and hypotension was managed with an infusion of IV phenylephrine. Regular arterial blood gas (ABG) analysis was done to monitor acid–base, oxygenation, and hemoglobin status; and the values of ABG remained unremarkable throughout. Intraoperatively, care was taken to avoid tachycardia, hypotension, hypercarbia, acidosis, and hypothermia; the child had a stable hemodynamic course during the intraoperative period [Figure 2]. The total duration of surgery and anesthesia were 225 and 370 min, respectively; the urine output was 375 mL and blood loss was 150 mL. During this period, 900 mL of crystalloids and 100 mL of packed RBC were transfused. On completion of an uneventful surgery, the neuromuscular blockade was reversed and the trachea was extubated after the child was fully awake. IV esmolol 0.5 mg/kg at extubation was administered to prevent the hemodynamic response. The postoperative course of the child was unremarkable and she was discharged from the hospital on the 6th postoperative day with the advice to follow-up.

Figure 2

Perioperative hemodynamic trend

DISCUSSION

KFS is a congenital, musculoskeletal condition characterized by the fusion of at least two vertebrae of the neck.[23] Common symptoms include a short-neck, low hairline, and restricted mobility of the upper cervical spine. VSD is a common cardiac manifestation. Central nervous system abnormalities such as Chiari malformation, spina bifida, or syringomyelia are commonly observed.[4] In this case, the major anesthetic concerns were anticipated difficult airway, structural cardiac pathology, prone position, and concerns pertinent to the pediatric age group.

Severe AS is defined according to an integrative approach considering valve area (less than 1.0 cm2 or 0.6 cm2/m2 body surface area, except in obese patients), and flow-dependent indices (maximum jet velocity 4 m/s and mean aortic pressure gradient ≥40 mmHg).[5] In cases of severe AS, intraoperative hypotension, myocardial ischemia/infarction, heart failure, arrhythmias, and sudden death are few common complications that can lead to high chances of mortality.[5] In the case of elective noncardiac surgery, the presence of symptoms is essential for decision-making.[6] In symptomatic patients, aortic valve replacement should be considered before elective surgery.[6] In patients who are not candidates for valve replacement, due either to high risks associated with serious comorbidities or refusal to undergo the operation, noncardiac surgery should be performed only if it is essential.[6] In this case, the child was asymptomatic and hence, the need for valvular surgery was ruled out in view of younger age group. Moreover, associated basilar invagination and atlantoaxial dislocation required immediate neurosurgical correction based on the progression of neurologic deficits. Hence, it was decided to do the neurosurgical procedure first before definitive treatment for the cardiac abnormality.

During the entire procedure, steps such as laryngoscopy, tracheal intubation, prone positioning, skin incision, bone drill, and brain stem handling might cause major hemodynamic alterations and can potentially trigger myocardial ischemia through an increase in myocardial oxygen demand, a reduction in myocardial oxygen supply, or both.[67] Because of a fixed cardiac output state in AS, systemic hypotension can reduce coronary perfusion pressure, which can cause myocardial ischemia and further reduction of contractility causing a reduction in blood pressure and coronary perfusion. Therefore, it is important to maintain the systemic vascular resistance (SVR) in such cases; using drugs such as norepinephrine and phenylephrine.[7] In our case, the infusion of phenylephrine at a dose of 0.5 µg/kg/min was used to maintain adequate SVR, which was gradually tapered off and stopped toward the end of surgery. Maintenance of sinus rhythm and treatment of arrhythmias must also be done, promptly.[7] Maintenance of adequate intravascular volume is important to ensure ventricular filling. Goal-directed fluid therapy (GDFT) and maintaining a track of cardiac output, SVV with adequate preload is of paramount importance. GDFT optimizes cardiovascular performance which helps in normal oxygen delivery to tissues with optimal pre-load and inotropic function using predefined hemodynamic targets.[6] Intraoperative transesophageal echocardiography (TEE) is a very useful tool in this context; it provides real-time assessment of ventricular dysfunction, mean aortic gradient, and ventricular filling, and helps manipulation of hemodynamics. As per ASA practice guidelines, TEE should be used for noncardiac surgical patients with known or suspected cardiovascular pathology that might result in hemodynamic, pulmonary, or neurologic compromise.[8] However, in this case, TEE could not be used owing to unavailability of a pediatric probe and the child was monitored using noninvasive cardiac output monitors such as Flotrac and ICON. The utility of Flotrac in children is uncertain,[910] whereas ICON has been validated for its use in children.[11] Nevertheless, both the technologies were utilized to optimize our management. Lastly, prompt reversal and smooth emergence with minimal cardiovascular stress should be ensured in such cases. Extubation in such a case mandates careful attention because of co-existing valvular pathology and fixed cervical spine after surgery. Hence, it is always better to extubate the patient when fully awake with preparedness for necessary re-intubation with all precautions for a potentially difficult airway; the airway-related complications could be as high as 27% after such procedures.[12] Severe postoperative pain, reported in 5–10% of patients, may increase sympathetic drive and delay in recovery.[13] Hence, adequate analgesic in the form of opioid alone or a combination of opioid and nonsteroidal anti-inflammatory drugs should be supplemented during the postoperative period.[13]

CONCLUSION

This case suggests that severe uncorrected AS may not be an absolute contraindication for noncardiac surgeries. In case of rapidly deteriorating neurological status, in patients with asymptomatic severe AS, neurosurgical procedures can be done with appropriate perioperative hemodynamic monitoring and adopting measures to deal with anticipated complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.