From an anesthetic point of view,1 premature and ex-premature infants are a vulnerable patient group. These infants are at risk of postoperative apnea, desaturation, cyanosis, and bradycardia after general anesthesia.2 Perioperative use of opioids is one of the causative factors for postoperative respiratory complications. Regional anesthesia is the most common modality to reduce the opioid requirement in these infants to minimize the risk of postoperative apnea.
Retinopathy of prematurity (ROP) is a potentially blinding eye disorder, and in its advance stage, vitreoretinal surgery is the only treatment modality. The number of ex-premature infants undergoing surgery for ROP has been increasing each year because of improved survival; however, no clinical data are available regarding the efficacy of peribulbar block for vitreoretinal surgery in these infants. We report our experience with the effects of peribulbar block in premature or ex-premature infants who underwent vitreoretinal surgery for ROP in terms of postoperative outcome, such as respiratory support requirements and intraoperative opioid use. RS participated in the anesthesia care of all patients. This report does not include any individual demographic data from which patients can be identified.
Twenty-four infants received peribulbar block for ROP surgery. The median (range) gestational age at birth and postconceptional age at the time of surgery was 28 (26–40) weeks and 52 (39–76) weeks, respectively. Sixteen infants were males and 8 were females. The median (range) body weight was 5 (2–9) kg. Demographic and perinatal details are provided in Table 1. All but one patient required neonatal intensive care unit (NICU) support and oxygen therapy after birth. Six infants required mechanical ventilation and 3 required continuous positive airway pressure. Seven infants had a history of apnea and 4 infants had a history of cyanosis. Two infants had a history of congenital heart diseases; one had an atrial septal defect and another had an atrial septal defect with patent ductus arteriosus. The infants’ median (range) preoperative hemoglobin was 10 (8.2–13.1) g%.
The fasting guidelines of Standard American Society of Anesthesiologists were followed in all infants. No premedication including anticholinergics were used. The operating room was kept warm, and a radiant warmer was used during anesthetic induction and reversal. After attaching routine monitors (electrocardiogram, arterial blood pressure, and pulse oximetry) to monitor heart rate (HR) noninvasive arterial blood pressure and oxygen saturation (SpO2), anesthesia was induced by gradually increasing the concentration of sevoflurane in oxygen. After attaining adequate depth of anesthesia, an IV cannula was inserted and atracurium was given at 0.5 mg/kg when adequacy of bag and mask ventilation was confirmed. The trachea was intubated in 23 infants using an appropriately sized uncuffed endotracheal tube. In one infant, an Ambu® laryngeal mask airway (Ambu A/S, Ballerup, Denmark) was used for securing the airway.
After securing the airway, a peribulbar block was given to all infants with standard aseptic precaution by an experienced ophthalmologist. Local anesthetic drug was prepared in a 2-mL syringe with a half-inch, 26-G needle attached to it. The needle was inserted at the junction of the medial two-thirds and lateral one-third of the inferior orbital rim, with the eye in neutral position.3 A combination of lidocaine (1%) and bupivacaine (0.25%) (1:1) was used in 18 patients; lidocaine (1%) alone was used in 2 patients and bupivacaine (0.25%) in another 4 patients. The median (range) volume of drug used was 1 (0.5–2.0) mL. Anesthesia details are provided in Table 2.
General anesthesia was maintained with isoflurane in air-oxygen targeting an isoflurane end-tidal concentration 0.8 minimum alveolar concentration. Ringer’s lactate solution was administered as per the “4-2-1 rule,” and capillary blood glucose monitoring was done intraoperatively. The median (range) capillary blood glucose was 100 (55–152) mg/dL, and none of the infants required glucose supplementation in the operating room. IV paracetamol 7.5 mg/kg was administered in the first 15 minutes as an infusion. None of the infants had a hemodynamic response to incision or insertion of a port. All patients had stable hemodynamics throughout the surgery, and no episode of hemodynamic alteration occurred that required intervention.
No statistical differences were found in HR or systolic and diastolic blood pressure at different time points (Fig. 1; Kolmogorov-Smirnov test for nonparametric data).
At the end of the surgery, inhaled agents were discontinued, and on return of respiratory effort, residual neuromuscular blockade was reversed with neostigmine 0.7 mg/kg and glycopyrrolate 0.1 mg/kg. The trachea was extubated when infants were fully awake and a regular tidal volume of at least 6 mL/kg without any episode of apnea was noted. Extubation was possible within 10 minutes of the end of surgery in the operating room in all cases except one, when extubation was delayed by 25 minutes because of poor respiratory effort. One infant had transient apnea and oxyhemoglobin desaturation up to 88% before extubation. In the postanesthesia care unit (PACU), all necessary equipment and drugs for emergency intubation and any other complications were ready. HR and SpO2 were monitored in all neonates during their PACU stay. Pain and hemodynamic assessments were performed by a nurse and supervised by an anesthesiologist. However, no formal documentation of postoperative pain was done. All infants in our series were consolable with the presence of the mother, and all of them were fed within 2 to 3 hours of surgery. Oxygen was supplemented for 1 to 2 hours, depending on maintenance of SpO2. No patient had any episode of apnea, desaturation, or bradycardia in the PACU. All patients were moved to the postoperative ward, where apnea monitoring was done for the next 24 hours. In the postoperative period, infants received oral paracetamol at 7.5 mg/kg at 8 hourly intervals. Seven infants had fever (skin temperature > 100°F) within 2 hours of surgery that responded to tepid sponging alone; no drug treatment was required.
The most important clinical end point of our series is that peribulbar block in premature and ex-premature infants is safe and may have anesthetic and analgesic-sparing effects because none of the infants had apnea, desaturation, or required postoperative NICU admission.
Peribulbar block has been used alone and in conjunction with general anesthesia in adults, as well as in children for vitreoretinal surgery, and was effective in reducing the incidence of oculocardiac reflex, surgical bleeding, postoperative pain, and postoperative nausea and vomiting.4–6 Sinha et al.,7 in a retrospective study, used 0.5% topical proparacaine drops, topical 2% lidocaine gel, and peribulbar block in preterm/ex-preterm infants for ROP surgery. They reported a 5.36% incidence of postoperative apnea, which is less than previous reports after hernia surgery under general anesthesia.8 Data of 3 infants who received peribulbar block in the study of Sinha et al. 7 have also been included in this report.
Regional anesthesia and analgesia in premature and ex-premature infants are mostly limited to hernia surgery. For hernia surgery, caudal epidural analgesia and spinal anesthesia have been suggested as the sole anesthetic technique to reduce or eliminate the need for general anesthesia and consequently postoperative apnea in preterm infants.9,10 Recently, with the widespread use of ultrasound, regional anesthesia is not limited only to caudal or spinal anesthesia.11
Although the use of regional anesthesia in preterm infants has been reported for laser treatment in ROP, it has not been reported for ophthalmic surgeries in this population.12 In the present series, an experienced ophthalmologist administered single inferotemporal injection for peribulbar block because it is safer and effective.13,14 We limited the dose of lidocaine and bupivacaine to 5 and 2 mg/kg, respectively, to minimize the possibility of local anesthetic toxicity.15
In the present series, intraoperative stable hemodynamics without opioid administration indicated an acceptable quality of analgesia. Aoyama et al.16 administered mean fentanyl 4.6 μg/kg in infants with ROP undergoing vitrectomy, and 20% of their infants required postoperative ventilation for >2 days. A frequent incidence of requiring postoperative ventilation may increase airway complications and respiratory infections along with the cost of treatment. We also used IV paracetamol in the postoperative period, which may also have eliminated the need for additional opioid analgesics.17 No child in our series required analgesics in the PACU, and all children were fully awake in the postoperative period; feeding was possible within 2 to 3 hours after surgery. The PACU at our institution is equipped with continuous electrocardiogram, HR and SpO2 monitoring, emergency airway equipment, resuscitative drugs, and trained nursing personnel under the supervision of an anesthesiologist.
The reduced use of perioperative opioids probably eliminated the risk of apnea, which would have necessitated a transfer to the NICU. It is worth mentioning that several risk factors for postoperative apnea were present, postconceptional age <52 weeks, hemoglobin <10 g%, history of apnea, and cyanosis. The most common postoperative complication in our series was fever, despite intraoperative IV paracetamol administration. However, fever was of short duration and responded to tepid sponging.
To the best of our knowledge, this series is the first to present clinical data showing possible avoidance of opioid consumption in preterm infants having vitreoretinal surgery for ROP with peribulbar block without any adverse effect.
Our report is a case series only and included a small number of infants. Further prospective studies are required to confirm our initial observation. We conclude that the use of peribulbar block in ex-premature infants may reduce opioid requirements and risks of postoperative apnea and desaturation.
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