Anesthesia for intraoperative radiation therapy in children

Outstanding contribution to pediatric anesthesiology: An interview with Dr. Robert H. Friesen

Dr. Robert H. Friesen, (1946-) Professor of Anesthesiology, Children's Hospital Colorado, University of Colorado, Anschutz Medical Campus, has played a pivotal and pioneering role in the development of pediatric and congenital cardiac anesthesiology. His transformative research included the study of the hemodynamic effects of inhalational and intravenous anesthetic agents in the newborn and the effects of anesthetic agents on pulmonary vascular resistance in patients with pulmonary hypertension. As a model clinician-scientist, educator, and administrator, he changed the practice of pediatric anesthesia and shaped the careers of hundreds of physicians-in-training, imbuing them with his core values of honesty, integrity, and responsibility. Based on a series of interviews with Dr. Friesen, this article reviews a career that advanced pediatric and congenital cardiac anesthesia during the formative years of the specialties.

Anesthesia complications of pediatric radiation therapy

PURPOSE

Complications of anesthesia for pediatric radiation therapy are imperative for both radiation oncologists and anesthesiologists to clinically assess and manage. We performed the first systematic review to date addressing this important issue.

METHODS

A systematic search of PubMed and EMBASE was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Searches were not restricted based on publication date. Nine original investigations were identified, analyzed, and collated for this report.

RESULTS

General anesthesia has proven superior to conscious sedation with regard to maintaining satisfactory procedural sedation while maintaining low respiratory and cardiovascular complication rates. Although agents such as ketamine (complication rates approaching 23%-24%) have been used in the past, other agents such as propofol and volatile anesthetics have lower complication rates because of improved drug side effect profiles (0.01%-3.5%). Most common complications are respiratory-based (eg, airway obstruction, broncho/laryngospasm, desaturation, apnea), followed by those that are cardiovascular-based (eg, tachy/bradycardia, arrhythmias, hypotension) and nausea/vomiting. Though procedure duration and anesthetic dose can be associated with higher complication risks, prior or concurrent chemotherapy does not confer added risks other than neutropenia-related sepsis. Other potential complications include those with vascular access devices, observed in up to 20% to 25%, with peripherally inserted central catheters having the highest rates of vascular complications and port catheters the lowest.

CONCLUSIONS

Rates of anesthetic complications encountered in pediatric radiation therapy are similar, if not lower, than rates reported in controlled operating room settings, implying that anesthesia for pediatric radiation therapy is safe, with low complication rates periprocedurally. Propofol infusion and oxygen delivery via nasal cannula offer the lowest immediate anesthetic complication rates and are hence most recommended for use. Though the long-term neurocognitive consequences of multiple anesthetics in pediatric patients have yet to be clearly defined, health care providers should be cognizant of the potentially serious implications.

Intraoperative radiotherapy for head and neck and skull base cancer

BACKGROUND

The purpose of this study was to evaluate the use of intraoperative electron beam radiotherapy (IORT) as an adjuvant modality in the treatment of advanced head and neck and skull base cancer.

METHODS

Between 1991 and 1996, 34 patients with squamous cell carcinoma (SCCA) and 10 patients with non-SCCA were enrolled in this prospective nonrandomized clinical trial. Most patients had been previously treated with combinations of surgery, external beam radiotherapy, and chemotherapy. The most frequent sites treated were the skull base (56%) and the neck (44%). IORT was delivered in a dedicated operating room suite with energies of 6 to 15 MeV (6 MeV most commonly used) at doses of 12.5 to 22.5 Gy.

RESULTS

At 2 years overall and disease-free survival was 32% and 21%, respectively, for the SCCA patients and 50% and 40%, respectively, for the non-SCCA patients. Tumor control rates at 2 years in the IORT field were 46% for the SCCA patients and 52% for the non-SCCA patients. For squamous cell histology, survival in patients with microscopic residual tumor did not differ from those with no residual tumor, but they both had significantly longer disease-free survival than those patients with gross residual at the time of IORT (p =.03), with a trend toward longer overall survival (p =.09). The only complication directly attributable to IORT was a neuropathy in a patient who received an IORT dose of 22.5 Gy (cumulative dose 130.1 Gy).

CONCLUSIONS

IORT at a dose of 12.5 Gy is safe and produces tumor control and survival for patients likely to have microscopic residual disease in sites difficult to resect such as the skull base.

Intraoperative radiotherapy in the treatment of neuroblastoma: report of a pilot study

BACKGROUND

External beam radiotherapy in advanced neuroblastoma is limited by the volume of normal radiosensitive tissues included in the radiation field. Limitations to external radiation are the late effects to these tissues. Intraoperative radiotherapy (IORT) delivers a single high-radiation dose to a tumor while displacing normal tissues that would have been included in an external field. Standard external radiotherapy can still be done after "boost" IORT.

METHODS

Eight advanced-stage neuroblastoma patients who received IORT as part of their multimodality therapy were reviewed to identify the impact of IORT on operative time, complications, and tumor control in the treatment field. The IORT was accomplished by patient transport from the OR to the radiation therapy suite; these were separated by three floors.

RESULTS

IORT added 30-75 min to the operative procedure. Tumors in the resection/IORT fields showed no evidence of disease (one), stable tumor size (six), and tumor recurrence (one). Two complications were identified: a urinary fistula and CO2 retention, which was detected and corrected before the IORT. Neither of these complications was related to the IORT. Two patients who had subsequent tumor resection after IORT demonstrated tumor differentiation to ganglioneuromatous tissue.

CONCLUSIONS

IORT usually can be completed in less than an hour. No IORT-associated complications were identified. IORT along with maximal tumor resection, external radiation, and chemotherapy enhances local tumor control.

Electron beam intraoperative radiation therapy for pediatric neoplasms

BACKGROUND

Intraoperative radiation therapy (IORT) has potential advantages over conventional external beam radiation in that a single large dose is delivered to the tumor and its regional bed at the time of surgical exploration. The therapeutic ratio is enhanced by direct tumor visualization, precise treatment volume, and exclusion of normal organs. In childhood, local tumor control is critical for lesions that cannot be totally excised or residual disease not ablated by systemic therapy.

METHODS

During the past decade, the authors evaluated IORT in pediatric patients with unresectable or recurrent tumors. Fifty-nine patients were treated, 48 for advanced malignant disease and 11 for histologically benign but locally aggressive tumors. Sixty-four operations were performed, during which 84 separate radiation fields were used. High energy electrons at 5-11 MeV were delivered at a dose of 1000-1700 cGy to a tissue depth of 0.5-3 cm.

RESULTS

Of 25 children with advanced neuroblastoma, 15 were alive 14-104 months (mean, 51 months) after treatment. The survival of all patients with solid malignancies was 63%. Local tumor control was achieved in 75% of children with cancer and 91% of those with benign tumors. Complications of IORT at the doses used were trivial.

CONCLUSIONS

Electron beam therapy can be safely and efficiently delivered to young patients during operations intended to treat the primary tumor. The outcome achieved for overall survival and local control of the primary tumor is encouraging, and an acceptable complication rate during intermediate to long-term follow-up has been noted.