Patient and operative factors associated with unanticipated intensive care admission and outcomes following posterior fossa decompressions in children: A retrospective study

Abstract Introduction Posterior fossa decompression for Chiari I Malformation is a common pediatric neurosurgical procedure. We sought to identify the impact of anesthesia‐related intraoperative complications on unanticipated admission to the intensive care unit and outcomes following posterior fossa decompression. Methods Medical records of all patients <18 years who underwent surgery for Chiari I malformation between 1/1/09 and 1/31/21 at the Ann & Robert H. Lurie Children's Hospital of Chicago were included. Records were reviewed for patient characteristics, anesthesia‐related intraoperative complications, postoperative complications, and surgical outcomes. The primary outcome was the incidence of unanticipated admission to the intensive care unit, and the primary variable of interest was an anesthesia‐related intraoperative complication. Patient, surgical characteristics, and year of surgery were also compared between patients with and without an unanticipated admission to the intensive care unit, and a multi‐variable adjusted estimate of odds of unanticipated admission to the intensive care unit admission following an anesthesia‐related intraoperative complication was performed. Secondary outcomes included anesthesia factors associated with an anesthesia‐related intraoperative event, and postoperative complications and surgical outcomes between patients admitted to the intensive care unit and those who were not. Results Two hundred ninety‐six patients with Chiari I Malformation were identified. Clinical characteristics associated with an unanticipated admission to the intensive care unit were younger age, American Society of Anesthesiologist (ASA) physical status >2 and an anesthesia‐related intraoperative complication. 29 anesthesia‐related intraoperative complications were observed in 25 patients (8.4%). Two of 25 patients (8%) with an anesthesia‐related intraoperative complication compared with 3 of 271 (1%) patients without anesthesia‐related intraoperative complication had an unanticipated admission to the intensive care unit, odds ratio 7.8 (95% CI 1.2–48.8, p = .010). When adjusted for age, sex, ASA physical status, presenting symptoms, concomitant syringomyelia, previous decompression surgery and year of surgery, the odds ratio for an unanticipated admission to the intensive care unit following an anesthesia‐related intraoperative complication was 5.9 (95% CI 0.51–59.6, p = .149). There were no differences in surgical outcomes between patients with or without an unanticipated admission to the intensive care unit. Conclusion Our study demonstrates that although anesthesia‐related intraoperative complications during posterior fossa decompression are infrequent, they are associated with an increased risk of an unanticipated admission to the intensive care unit.


| INTRODUC TI ON
Studies reporting the effects of patient and surgical factors on perioperative complication rates for children undergoing neurosurgical operation including craniosynostosis repair, 1-3 epilepsy surgery, 4 and other neurosurgical procedures (for hydrocephalus, spinal and cranial anomalies, brain tumor, cerebellar cancer, and trauma) 5  For this reason, we performed a retrospective study to examine clinical characteristics and intraoperative and postoperative adverse events for this surgical patient population. Our overall aim was to identify patient and operative predictors and specifically the impact of an anesthesia-related intraoperative complication on the odds of an unanticipated admission to the intensive care unit as a marker of a clinically significant adverse event in this population. Knowledge of these factors may allow for improved anesthetic planning and management in order to reduce and prepare for these complications. Specifically, we hypothesized that intraoperative anesthesia-related complications would occur in approximately 10% of patients, 5 and that an intraoperative anesthesia-related complication would increase the odds ratio for an unanticipated intensive care unit admission following posterior fossa decompression for Chiari I Malformation.

| MATERIAL S AND ME THODS
Approval for this retrospective chart review study was granted by the Institutional Review Board of the Ann & Robert H. Lurie Children's Hospital of Chicago (IRB 2016-110). A waiver of informed consent was granted by the IRB as the study was deemed of minimal risk to subjects, and data were acquired from preexisting records. The hospital records of all patients aged less than 18 years old who un- Patient medical, anesthesia, and surgical records were queried for the following: demographic and clinical variables including age, When adjusted for age, sex, ASA physical status, presenting symptoms, concomitant syringomyelia, previous decompression surgery and year of surgery, the odds ratio for an unanticipated admission to the intensive care unit following an anesthesia-related intraoperative complication was 5.9 (95% CI 0.51-59.6, p = .149). There were no differences in surgical outcomes between patients with or without an unanticipated admission to the intensive care unit.

Conclusion:
Our study demonstrates that although anesthesia-related intraoperative complications during posterior fossa decompression are infrequent, they are associated with an increased risk of an unanticipated admission to the intensive care unit.

K E Y W O R D S
child, complications, general anesthesia, neurosurgery

What is already known about the topic
Posterior fossa decompression for Chiari I Malformation is a common neurosurgical procedure in pediatric anesthesia practice, but the impact of anesthesia-related intraoperative complications on the incidence of unanticipated intensive care admission and 30-day outcomes is unknown.

What new information this study adds
This study confirmed the rate of anesthesia-related complications during posterior fossa decompression in children was low (<10%); however, 2 of 25 patients with an anesthesia-related intraoperative complication (8%) compared with 3 of 271 (1%) without anesthesia-related intraoperative complication had an unanticipated admission to the intensive care unit, unadjusted odds ratio 7.8 (95% CI 1.2-48.8, p = .010) and an adjusted odds ratio of 5.9 (0.51-59.6, p = .149). Thirty-day outcomes were not different in patients with or without an unanticipated admission to the intensive care unit. weight, height, gender, surgical diagnosis, initial presenting symptoms leading to diagnosis of Chiari I malformation, and medical comorbidities (cardiac, pulmonary, renal, neurologic); evidence of upper respiratory infection; prior perioperative anesthetic history (nausea/vomiting, difficult airway); American Society of Anesthesiologists (ASA) physical status classification system; and preoperative clinical and laboratory test results. Intraoperative variables were abstracted from the anesthesia records, including but not limited to induction type, medications used, fluid administration, estimated blood loss, changes in neuromonitoring signals, duration of procedure, and any complication or adverse clinical event. Intraoperative anesthesia-related complications were defined before data collection and considered relevant when an intervention was needed beyond titration of anesthetic agents. These included any cardiac event requiring medication intervention (bradycardia, hypotension, hypertension, or arrhythmias requiring medication treatment such as atropine, phenylephrine, labetalol, or lidocaine, respectively), desaturations defined as a peripheral oxygen saturation less than 93% for greater than 10 min, blood

| Statistical analysis
The primary outcome assessed was the incidence of an unantici-

| RE SULTS
Two hundred ninety-six patients who underwent posterior decompression surgery for Chiari I Malformation were identified.
Five patients (5 of 296, 1.7%) had an unanticipated intensive care unit admission following surgery, and thirteen patients had a planned admission to the intensive care unit. Univariable analysis of the clinical characteristics associated with an unanticipated admission to the intensive care unit are shown in Table 1 with hemodynamic changes, which resolved without sequelae. Six patients while in the prone position required adjustments in their airway (three for repositioning of endotracheal tube due to mainstem intubation, two patients requiring flip back to supine position for reintubation due to obstruction, and one kinked tube that resolved after evaluation with fiber-optic), and six patients were given naloxone for over-sedation noted during emergence while trying to extubate. Two patients received intraoperative red blood cell transfusion. Lastly, four of 142 patients with neuromonitoring had decreased SSEP signals: two resolved spontaneously, one improved after nitrous oxide was turned off, and one improved after a propofol drip was initiated and the inhalational agent was discontinued.
All patients received general anesthesia with inhalation maintenance, and 95% received intraoperative neuromuscular blockade. A total of 291 patients (98%) received intraoperative opioids, with 47 (16%) receiving intraoperative dexmedetomidine. The association of anesthesia factors with an intraoperative anesthesia-related event is shown in Table 2.  Table 4. The most frequent postoperative complications included TA B L E 1 Clinical characteristics, intraoperative anesthesia complications, surgical factor, and year of surgery in subjects with and without an unanticipated intensive care unit admission following posterior fossa decompression surgery for Chiari I Malformation   Intraoperative fluids (mls/kg/hr) 10 (7-14) 11 (8)(9)(10)(11)(12)(13)(14) .  Upper airway obstruction was more common in patients with un-

| DISCUSS ION
The results of our study demonstrate a low incidence of intraoperative anesthesia-related complications in children undergoing posterior fossa decompression for Chiari I Malformation.
Nevertheless, we found an association between ASA physical status >2, younger age, and an anesthesia-related intraoperative  only two studies reported complications which may be related to anesthesia. One of 24 patients had postoperative nausea in one study, 12 and another trial noted ventilatory failure requiring reintubation in two of 43 patients. 13 Our study, which specifically looked at complications related to anesthesia for this procedure, confirmed the minimal anesthetic complications noted by prior investigations.

CO N FLI C T O F I NTE R E S T
The authors have no conflicts of interest to declare.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.