|Year : 2017 | Volume
| Issue : 1 | Page : 237-241
Subarachnoid anesthesia (with and without sedation) versus general anesthesia for ex-preterm neonates undergoing elective infraumbilical operations
Mostafa M Hussein, Raham H Mostafa
Department of Anesthesia and Intensive Care, Faculty of Medicine, Ain Shams University, Cairo, Egypt
|Date of Web Publication||3-Aug-2018|
Mostafa M Hussein
5 Abdelazim Salama Street, Nasr City, Cairo 11727
Source of Support: None, Conflict of Interest: None
Background Postoperative respiratory problems, especially apnea, is a common postoperative complication in ex-preterm neonates undergoing infraumbilical operations. So, most of these neonates require close postoperative monitoring for at least 12 h to avoid this hazard. Postoperative apnea is related more to the use of respiratory depressant drugs used during general anesthesia.
Aim The aim was to evaluate safety and effectiveness of spinal anesthesia in ex-preterm infants undergoing infraumbilical operations and evaluate its role in elimination of routine postoperative hospital stay for apnea monitoring.
Settings and design A prospective single-blinded randomized study was conducted.
Materials and methods From March 2015 to March 2016, 105 ex-preterm neonates (gestational age <37 weeks), with postconceptual age at surgery less than 60 weeks, undergoing elective infraumbilical operations were studied prospectively. Patients were divided randomly into three groups (35 patients each). Group I received spinal anesthesia without sedation (only sugared pacifier), group II received spinal anesthesia with sedation in the form of ketamine/midazolam, and group III received general anesthesia with caudal analgesia. Postoperative apnea, bradycardia, and oxygen saturation were observed and compared for 12 h after operation. The primary outcome measures were postoperative apnea, postoperative bradycardia, and SpO2. The secondary outcome measures were postoperative complications (e.g. hypotension) and the need for postoperative respiratory support.
Results No patients in group I developed any attacks of postoperative apnea, postoperative bradycardia, or hypoxia. On the contrary, 11 patients in group II and 16 patients in group III developed attacks of postoperative apnea and hypoxia and required postoperative respiratory support.
Conclusion Spinal anesthesia without sedation is safe and effective for infraumbilical operations in ex-preterm neonates with short hospitalization.
Keywords: apnea, infraumbilical surgery, preterm infants, spinal anesthesia
|How to cite this article:|
Hussein MM, Mostafa RH. Subarachnoid anesthesia (with and without sedation) versus general anesthesia for ex-preterm neonates undergoing elective infraumbilical operations. Ain-Shams J Anaesthesiol 2017;10:237-41
|How to cite this URL:|
Hussein MM, Mostafa RH. Subarachnoid anesthesia (with and without sedation) versus general anesthesia for ex-preterm neonates undergoing elective infraumbilical operations. Ain-Shams J Anaesthesiol [serial online] 2017 [cited 2018 Nov 20];10:237-41. Available from: http://www.asja.eg.net/text.asp?2017/10/1/237/238474
| Introduction|| |
Apnea of prematurity is a very common neonatal hazard, accounting for 25% of preterm and ex-preterm infants following recovery from general anesthesia. The distributions of postoperative apnea are either central (70%), obstructive (10%), or mixed (20%) .
High-risk infants for postoperative apnea are those who are born prematurely (<37 weeks), infants with multiple congenital anomalies, infants with a previous history of postoperative apnea and bradycardia, and those with chronic lung disease. Apneic spell is defined as a pause in breathing of more than 20 s or one of less than 20 s associated with bradycardia and/or cyanosis .
The incidence of apnea is related to the gestational as well as postconceptual age (PCA). An infant born at a lower gestational age is more likely to have apnea than one with same PCA but born later. This risk reduces with increase in duration of PCA up to 60 weeks PCA .
Apnea in premature infants is exacerbated by hypoxia, sepsis, intracranial hemorrhage, metabolic abnormalities, hypo/hyperthermia, upper airway obstruction, heart failure, anemia (hematocrit <30%), vasovagal reflexes, and drugs (including prostaglandins and anesthetic agents) .
Decreased ventilatory control and decreased response to hypoxia and hypercarbia may be increased by anesthetic agents. The highest incidence of significant apnea and bradycardia is in the first 4–6 h postoperatively, but it was reported to be up to 12 h after surgery. High-risk infants for development of postoperative apnea may benefit from a regional anesthetic as opposed to a general anesthetic .
Therefore, these infants require postoperative monitoring in high dependency unit for at least 12 h and should not be anesthetized as outpatients even if regional anesthesia has been administered. In fact, some authors suggest that wherever possible, anesthesia should be delayed until the ex-premature infant is older than 52 weeks PCA .
| Materials and methods|| |
Our study was carried out in the Pediatric Surgery Department of Ain Shams University educational hospital in the period from March 2015 to March 2016. After approval of local ethical committee, 105 pediatric patients of both sexes, American Society of Anesthesiology I and II physical status, were included in our study. The age group included formerly preterm neonates with postconceptual age less than 60 weeks, undergoing elective infraumbilical surgery. Detailed informed patient consents were taken from parents. Preanesthetic evaluation was done to all pediatric patients included in the study.
Patients were excluded if they have known allergy to local anesthetics, coagulopathy, pre-existing cardiac, metabolic or neuromuscular diseases, uncontrolled convulsions, local infection at puncture site, or parent refusal.
Patients were randomly allocated by sealed envelopes using computer-generated table into three groups (35 patients each). In all groups, no premedications were given. Intravenous cannula was inserted and secured. No fluid preloading was given.
Group I (35 patients) included patients who received spinal anesthesia without sedation (only sugared pacifier was used). Group II (35 patients) included patients who received spinal anesthesia with sedation in the form of intravenous ketamine (1 mg/kg) plus intravenous midazolam 50 µg/kg. Sedation in group II was given after performing the subarachnoid block. Under aseptic condition, spinal anesthesia was performed through midline approach while the patient is in the sitting position and supported by an assistant. After local skin infiltration with 1% lidocaine, lumbar puncture was done in L4/L5 interspace using 25-G 25-mm pencil-point spinal needle. Hyperbaric bupivacaine 0.5% (0.5 mg/kg) was injected in the subarachnoid space after getting free flow of cerebrospinal fluid. Drug injection was done using 1-ml syringe, which was prepared and the correct dose was calculated before dural puncture. After injection, the infant was placed in the supine position. Successful spinal block was proved by sudden and complete loss of leg movement with normal tone in both arms indicating that sensory level was below C8. In groups I and II, oxygen was given through nasal cannula at a rate of 3 l/min. Neonates with failed spinal anesthesia were anesthetized with general endotracheal anesthesia and excluded from the study.
Group III (35 patients) included patients who received general anesthesia with 2 minimum alveolar concentration (MAC) sevoflurane in 100% oxygen and muscle relaxation with atracurium (induction dose 0.5 mg/kg and maintenance dose 0.1 mg/kg). After insertion of a correctly sized endotracheal tube, caudal analgesia was done using 0.25% bupivacaine 0.5 ml/kg. Neuromuscular block was antagonized at the end of surgery with atropine and neostigmine under guidance of neuromuscular monitoring.
Routine intraoperative monitoring was applied to all patients [i.e. ECG, pulse oximetry, noninvasive blood pressure (BP), and temperature monitoring]. Warming blankets were used to minimize heat loss in all infants.
Intraoperative sedation level in groups I and II was assessed, every 5 min till end of surgery, using sedation/agitation scale (SAS) ([Table 1]) . During the operation, the infant in group I was comforted by the anesthesiologist to prevent excessive upper limb movement, with the help of a sugared pacifier.
On completion of operations, and after fulfilling criteria of recovery from general anesthesia in group III, all patients were transferred to intermediate care unit, warming blankets was used, and nasal oxygen was applied at a rate of 3 l/min. Continuous monitoring were done for 12 h postoperatively. Monitoring was done by bedside monitor which measures SpO2. Respiratory rate and heart rate (HR) were measured through ECG leads connected to patients’ chest. The monitor alarm was adjusted to sound when respiration ceases for more than 20 s (i.e. apnea) or if the HR decreases less than 100 beats/min (i.e. bradycardia) for more than 20 s or SpO2 decreases to less than 90%. Noninvasive BP was monitored, and evidence of hypotension (i.e. >20% decrease in systolic BP from baseline) was treated with 10 ml/kg intravenous crystalloid.
These data (i.e. HR, respiratory rate, SpO2, and mean BP) were recorded every hour up to 12 h postoperatively. The number and timing of apnea, bradycardia, and hypotensive attacks were recorded and compared in the three groups. The observer who monitored the patients was blind to the type of anesthetic technique and group allocation.
Infants developing attacks of apnea or bradycardia in the postoperative period were managed with tactile stimulation; if there was no response, bag and O2 mask ventilation together with airway positioning and suctioning were done. Persistent bradycardia despite previous measures was treated with intravenous atropine 0.01 mg/kg. Infants who developed apnea attack were kept on O2 therapy in the intermediate care unit for further 12 h.
The primary outcome measures were postoperative apnea, postoperative bradycardia, and postoperative SpO2. The secondary outcome measures were postoperative complications (e.g. hypotension), the need for postoperative respiratory support, and SAS score.
A sample size of 98 achieves 80% power to detect a 15% difference in incidence between the three groups with an effect size (W) of 0.3500. χ2-Test with a significance level (α) of 0.05 was used. A total of 35 patients per group were included to replace any dropouts.
Data were analyzed using SPSS 17 for Windows (SPSS; SPSS Inc., Chicago, Illinois, USA). Analysis of variance was used to compare the three groups for quantitative parametric data with post-hoc Tukey’s test performed if there was a significant difference among the groups. χ2-Test was used for comparison of qualitative data. Continuous parametric data were presented as mean±SD, categorical data were presented as number and percentage of patients, and nonparametric data were compared using Mann–Whitney test and were expressed as median (interquartile range). P values of less than 0.05 were considered significant.
| Results|| |
A total of 105 patients were enrolled in our study. There was no statistically significant difference among the three groups regarding demographic data, duration of anesthesia, and duration of surgery (P>0.05) ([Table 2]).
|Table 2 Comparison of demographic data, duration of anesthesia, and duration of surgery among the three groups|
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[Table 3] shows a comparison among the three groups regarding postoperative apnea, postoperative bradycardia, oxygen saturation, respiratory support, and hypotension. Regarding apneic spells, we noticed that no patients in group I had experienced postoperative apneic spills. On the contrary, 11 (31.4%) patients in group II and 16 (45.7%) patients in group III had experienced postoperative apnea (P<0.001).
|Table 3 Postoperative apnea, postoperative bradycardia, SpO2, respiratory support, and postoperative hypotension|
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Postoperative apnea time was 3.49±1.56 and 3.97±1.68 h in group II and III, respectively. In group II, eight patients developed one attack of apnea, two patients developed two attacks, and one patient developed three attacks. In group III, 10 patients developed one attack of apnea, four patients developed two attacks, and two patients developed three attacks ([Table 4]).
The same finding was noticed for postoperative bradycardia; no patients in group I had experienced postoperative bradycardia. On the contrary, 11 (31.4%) patients in group II and 16 (45.7%) patients in group III had experienced postoperative bradycardia (P<0.001).
Mean intraoperative and postoperative oxygen saturation was always high in group I as compared with the other two groups. No patients in group I needed respiratory support. On the contrary, 11 patients in group II and 16 patients in group III needed respiratory support. Respiratory support ranged from tactile stimulation to bag and mask ventilation. None of these apneic episodes required intubation and ventilation.
Two patients in group I, two patients in group II, and three patients in group III experienced hypotension, and the difference was nonsignificant (P>0.05) ([Table 3]).
No significant difference was observed among the three group regarding mean intraoperative and postoperative temperature (P=0.52).
Intraoperative sedation levels were compared between group I and group II according to SAS. Patients in group II were at deeper sedation level than patients in group I throughout the operation. At 5 min after spinal anesthesia, SAS was 5 (4–5) in group I compared with 1 (1–1) in group II. At 30 min after spinal anesthesia, SAS was 4 (3–4) in group I compared with 2 (2–3) in group II (P<0.001) ([Table 5]).
|Table 5 Intraoperative sedation-agitation scale comparison between group I and group II|
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| Discussion|| |
Neonatal spinal anesthesia, especially in ex-premature neonates, is gaining popularity and become a common practice in some pediatric surgery departments. The advantages are the avoidance of respiratory depressant drugs used during general anesthesia and eliminating the need for postoperative respiratory support.
In our study, we examined the effect of spinal anesthesia alone without any sedation on the incidence of postoperative apnea. Only sugared pacifier was used to sedate the infants. We detected that no patients in this group experienced any attacks of postoperative apnea or bradycardia, and no one needed any postoperative respiratory support. On the contrary, patients who received spinal anesthesia with intravenous sedation (midazolam plus ketamine) and those who received general anesthesia experienced attacks of postoperative apnea and bradycardia (11 patients in group II and 16 patients in group III).
Multiple previous studies have demonstrated that preterm infants have a higher incidence of respiratory problems than full-term infants. The risk of apnea in preterm infants undergoing inguinal herniorrhaphy increased to 37% following general anesthesia compared with 89% rate for spinal anesthesia with ketamine sedation and 0% apnea rate with spinal anesthesia alone .
Many factors are implicated in the development of apneic spell in ex-preterm neonates. These factors include diaphragmatic fatigue, diminished central respiratory drive, hypothermia, anemia, airway obstruction, residual effect of inhaled anesthetic, and muscle relaxant ,.
A study done by Wellborn et al.  compared spinal and general anesthesia in former premature infants. The study showed that spinal anesthesia without ketamine sedation was not accompanied with postoperative apnea, whereas neonates receiving general anesthesia or spinal anesthesia with intramuscular ketamine sedation (1–2 mg/kg before placement of the spinal anesthetic) developed 31 and 89% postoperative apnea, respectively .
In infants, metabolic rate of midazolam is lower than in adults. Midazolam elimination is approximately 4–6 h in neonates and up to 22 h in premature infants. Half-life of midazolam is 3.3-fold longer and clearance is 3.7-fold smaller than in adults .
A study done by Frumiento et al.  in 2000 concluded that awake spinal anesthesia, without sedation, reduced the incidence of postoperative apnea and need for respiratory support. It has been documented in the literature that subarachnoid anesthesia itself has a sedating effect. A study done by Hermanns et al.  evaluated sedation during spinal anesthesia in infants. One of the possible mechanisms for sedation is decreased afferent conduction to the reticulothalamocortical pathways and hence reduced excitability and arousal to the brain .
In a small randomized trial, Williams et al.  compared spinal anesthesia and general anesthesia with sevoflurane on postoperative recovery after inguinal herniotomy in ex-premature infants. They concluded that apnea and bradycardia occurred three times more frequent in the sevoflurane group .
A limitation to our study was that we did not include the preoperative hematocrit level as a risk factor for development of postoperative apnea. Anemia (i.e. hematocrit <30%) seemed as an important risk factor predisposing to postoperative apnea. Another limiting factor was the short duration of spinal anesthesia in neonates and thus not suitable for long-duration operations.
| Conclusion|| |
Subarachnoid block without sedation (only sugared pacifier) is an excellent choice for ex-preterm neonates with PCA less than 60 weeks undergoing infraumbilical operations allowing calm patients without significant agitation.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]