Anesthesia for repair of anorectal malformations in infants in low resource environments: is ketamine-dexmedetomidine combination plus epidural analgesia the solution?
Lynne G. Maxwell, MD and Myron Yaster, MD
The reports of the use of caudal/epidural analgesia/anesthesia in children for abdominal surgery are fundamental to the history and evolution of these techniques. One of the earliest and largest case series was the report by McGown from Zimbabwe in 1982 of 500 cases of children from infancy to 10 years of age who received single injection caudal analgesia for infradiaphragmatic surgery.1 Caudal injection was accomplished after oral premedication with hyoscine (scopolamine) and trimeprazine (a phenothiazine), after which patients were further sedated with intravenous thiopentone. Most patients did not receive further sedation, but some received additional thiopental as needed. Surgeries, which ranged from hip surgery to vagotomy and pyloroplasty, were successfully performed with this anesthetic technique in 86% of patients. The primary focus of McGown’s report was the correlation of the volume of local anesthetic administered (lidocaine or bupivacaine with epinephrine) with the upper extent of the block.
Subsequent reports, such as Bösenberg et al’s elegant description of placement of thoracic epidural catheters via the caudal route in infants (20 reported)2, involved infants in whom general anesthesia was induced and intubation performed prior to block placement.
Many low resource settings where children undergo surgery lack essential equipment and medications required to administer general anesthesia safely. In such settings, ketamine has long been used as a premedication and sedative for children undergoing surgery, sometimes with regional anesthesia. In some series, ketamine has been supplemented by other agents, such as midazolam, as reported by Piraccini et al, who administered ketamine intramuscularly followed by intermittent boluses of ketamine and midazolam in children undergoing orthopedic surgery with spinal anesthesia in Algeria.3 In the United States, older infants undergoing urologic surgery with spinal/caudal catheter analgesia at Nationwide Children’s Hospital have done well with dexmedetomidine infusion for sedation.4
The focus of today’s PAAD is the report of a small case series of 4 infants in Guinea Bissau undergoing repair of anorectal malformations who received sedation with a ketamine-dexmedetomidine combination infusion and epidural catheter analgesia.
Original Article
Vila Moutinho Tavares S, Tavares JC, Borges Marques J, Teixeira de Figueiredo J, Passos de Souza RL. Ketamine-dexmedetomidine combination for sedation in pediatric major surgery in a low-income country. Paediatr Anaesth. 2023 Apr;33(4):278-281. PMID: 35445494
In the setting in which these surgeries were performed, there was limited oxygen supply, no anesthesia machines appropriate for pediatric use, or critical care resources. Patients ranged in age from 6 to 12 months and 6 – 9 kg. Appropriate monitors (pulse oximetry, ECG, NIBP, temperature) were employed. Patients had IV access placed prior to surgery and were sedated with a ketamine (1 mg/ml) – dexmedetomidine (1 mcg/ml) solution (ketodex) starting with 1 ml/kg with further increments administered to achieve sedation adequate for lumbar epidural catheter placement, which was accomplished with ultrasound visualization. Epidural was dosed with bolus levobupivacaine 0.25% or ropivacaine 0.2%, with repeated bolus doses every 90 minutes. Surgical durations ranged from 1 hr 45 min to 4 hours. No supplemental oxygen or airway instrumentation was necessary. Patients were operated on in the prone and or supine position, as required. Ketodex was continued by either incremental bolus every 30 minutes or by infusion of 1.25 – 1.5 ml/kg/hr. One patient had increased oral secretions but no laryngospasm or bronchospasm occurred. Postoperative analgesia consisted of acetaminophen and epidural infusion of 0.1% ropivacaine at 2.4 ml/hr using an elastomeric infusion pump.
This is a small series reporting complex anorectal surgery in both supine and prone infants utilizing epidural catheter analgesia and ketodex sedation. The combination of ketamine and dexmedetomidine encompasses the use of two agents, neither of which cause respiratory depression and which have opposing hemodynamic effects. Dexmedetomidine may mitigate ketamine’s sympathetic stimulation and emergence agitation, and ketamine provides more potent analgesia than dexmedetomidine.
This combination of ketamine and dexmedetomidine has previously been reported to provide safe and effective sedation for MRI in 3 patients with Trisomy 21 and obstructive sleep apnea.5
As the authors conclude, reported clinical experience with this drug combination for sedation in infants and children is limited and further studies should be done. If any of you have experience with ketodex in your home institutions or in low resource settings, please let us know and we will post in a reader response.
PS: This is a good opportunity to remind, really urge, all of our readers to consider donating to Lifebox. Lifebox’s mission is to provide pulse oximeters and improve the safety and quality of anesthesia and surgery throughout the world.
https://donate.lifebox.org/give/423146/#!/donation/checkout.
References
1. McGown RG. Caudal analgesia in children. Anaesthesia 1982 37: 806-818.
2. Bösenberg AT, Bland BA, Schulte-Steinberg O, Downing JW. Thoracic epidural anesthesia via caudal route in infants. Anesthesiology. 1988; 69(2):265-9.
3. Piraccini E, Albarello R, Biagini C, Novi A, Agnoletti V, Gambale G. Spinal anesthesia plus ketamine-midazolam sedation for pediatric orthopedic surgery in a developing country. HSR Proc Intensive Care Cardiovasc Anesth. 2012; 4(3):176-8.
4. Jayanthi VR, Spisak K, Smith AE, Martin DP, Ching CB, Bhalla T, Tobias JD, Whitaker E. Combined spinal/caudal catheter anesthesia: extending the boundaries of regional anesthesia for complex pediatric urological surgery. J Pediatr Urol. 2019; 15(5):442-447.
5. Luscri N, Tobias JD. Monitored anesthesia care with a combination of ketamine and dexmedetomidine during magnetic resonance imaging in three children with trisomy 21 and obstructive sleep apnea. Paediatr Anaesth. 2006;16(7):782-6.