Intraoperative Management: Considerations for Specific Procedures in Children with Cancer

Anesthetic Management

The anesthetic management begins with a careful review of the child’s history, symptoms, clinical signs, and radiographic images (computed tomography and/or chest x-ray). In general, patients without orthopnea or cardiovascular symptoms and minimal radiographic evidence of airway obstruction may likely be anesthetized safely. However, physical signs and radiographic evidence have not been consistently shown to be predictive of potential complications; therefore general anesthesia or deep sedation should be avoided whenever possible, and when required, it is essential that the anesthesiologist establishes communication with the surgeon, has a set plan for sedation or anesthesia, and has a plan for rescue in the event of cardiopulmonary compromise. These include repositioning the patient (lateral or prone), the ability to perform rigid bronchoscopy to relieve tracheal compression, and the ability to perform a sternotomy and provide cardiopulmonary bypass or extracorporeal membrane oxygenation (ECMO).

Patients with signs of orthopnea, stridor, dyspnea at rest, and/or a >70% reduction in tracheal cross-sectional area are deemed high-risk, and general anesthesia should be avoided unless absolutely necessary. In older children, tissue diagnosis under local anesthesia has been associated with lower risk of anesthetic complications and has been successfully accomplished in several series. ^, Distraction techniques such as counting, listening to music, and nonprocedure-related talk have been shown to be effective. However, younger children and those undergoing surgical resection of large mediastinal masses may require a general anesthetic. In this instance, an anesthetic plan that ensures spontaneous respiration is generally preferable. Spontaneous ventilation typically preserves the patency of the intrathoracic airways. On the other hand, positive pressure ventilation may worsen airway compression (e.g., through neuromuscular blockade and/or deep anesthesia reducing support of the surrounding tracheobronchial musculature) and also reduce cardiac output by reducing venous return.

The airway may be managed by mask ventilation only, with a laryngeal mask airway, or with endotracheal intubation. Several methods have been described for the maintenance of anesthesia, including a mixture of sevoflurane in oxygen and halothane in heliox, and low-dose infusions of propofol, dexmedetomidine, and ketamine. The ability of dexmedetomidine and ketamine to provide sedation with minimal respiratory depression has proven beneficial in anesthetizing children with anterior mediastinal masses.

It is noteworthy that several authors have reported cases where intubation has been successfully performed in children with mediastinal masses. ^, In the event that an endotracheal intubation is necessary, advancement of the endotracheal tube past the segment of obstruction, typically through external compression, may have to be performed. Regardless of the choice of airway management, neuromuscular blockade is generally not recommended because the relaxation of supporting tracheobronchial musculature may contribute to further worsening of airway compromise. However, if neuromuscular blockade is deemed necessary, it is imperative to establish the ability to adequately ventilate the patient before administering muscle relaxants.

Summary

The management of the child with an anterior mediastinal mass poses a significant challenge to anesthesiologists. Potential respiratory and cardiovascular complications may be exacerbated under anesthesia, and plans to manage potential complications should be communicated to the entire team before initiation of care. Where possible, diagnostic procedures are best performed with local anesthesia with minimal-to-no sedation. Where deep sedation or general anesthesia is required, maintenance of spontaneous ventilation with or without an endotracheal tube is preferable. Neuromuscular blockade should be avoided whenever possible.

Airway Management

Several studies have demonstrated that anesthesia in children undergoing radiation therapy may be safely performed by spontaneous ventilation and an unprotected airway. In a large series of 340 children who had undergone 9328 radiotherapy procedures under anesthesia, supplemental oxygen was provided with a face mask or nasal cannula. In another large series describing the anesthetic management of 177 children who had undergone 3833 radiotherapy procedures, supplemental oxygen was provided by face mask in both the supine and prone positions. The placement of an oral airway or laryngeal mask airway was required in rare cases.