May 29, 2001

Post-operative recovery after inguinal herniotomy in ex-premature infants: comparison between sevoflurane and spinal anaesthesia

Williams JM, Stoddart PA, Williams SAR, Wolf AR. Br J Anaesth 2001; 86: 366-71

Commentary by Charles Coté, M.D.

The risk for post-operative apnea in former preterm infants has been well documented. A variety of studies carried out in a number of institutions have demonstrated how difficult it is to study a focused problem (apnea) in a small population, i.e., former preterm infants undergoing just inguinal herniorrhaphy [3-11]. One review which combined the results from four institutions over 6 years found that gestational age (GA) and postconceptual age (PCA) were independent risk factors, i.e., if two patients were born at 32 weeks GA and one was operated upon at 46 weeks PCA and the other at 52 weeks PCA, the one operated upon at 46 weeks PCA would be at greater risk for developing apnea [1]. Likewise if one baby was born at 28 weeks GA and another at 32 weeks GA and both were operated upon at 52 weeks PCA, the infant who was 28 weeks GA would be much more likely to develop postoperative apnea. Another independent risk factor was a hematocrit < 30 percent. In those infants there was no effect of GA or PCA suggesting that even older patients (> 55 weeks PCA) were still potentially at risk [1,9].

The limitation of the combined analysis was the modest number of patients in the older age groups at the time of surgery. An interesting observation was that the incidence of apnea was higher but equal in the two institutions that used computer recordings compared with the two institutions that relied upon nursing observations. Subsequent studies have shown a reduced incidence of apnea in infants undergoing their procedure with a regional technique compared with those undergoing the procedure with general anesthesia [2,11]. However, if any sedative such as ketamine or midazolam was added to the spinal, then apnea occurred at an equivalent or higher rate [11]. Thus it appeared that unsupplemented spinal anesthesia was the only technique that reduced the incidence of apnea. However even this technique did not reduce the incidence to zero, suggesting that patients still need to be admitted to a monitored bed following repair. In the March 2001 issue of BJA, Williams et al report their experience comparing spinal anesthesia with bupivacaine with general anesthesia with sevoflurane [12]. The authors speculated that the enhanced recovery characteristics of sevoflurane would result in recovery profiles similar to those found with spinal anesthesia. Instead, the authors found that sevoflurane unmasked abnormalities in respiration (similar to other inhalation agents) and that spinal anesthesia resulted in a lower incidence of apnea. However the authors point out that attempts at spinal anesthesia failed in 4 infants and that attempts at placing the spinal were "stressful" for the infants. They concluded that although spinal anesthesia resulted in a lower incidence of apnea, post-operative monitoring is so sophisticated that there is a high detection rate. There did not seem to be a great advantage to "routinely subjecting our patients to an awake technique that is potentially stressful". There are two important lessons here: 1) supplemented spinal anesthetics are just as risky as general anesthesia. 2) If one does not do a procedure in a specific population every day, there is a clinically important failure rate. Even in the hands of experienced pediatric anesthesiologists, there is a high failure rate for a spinal in an infant. My guess is if we had neonatologists performing the spinal then the failure rate would be lower. The bottom line is that we trade off a stressful procedure (a spinal tap) for reducing apnea but we can provide a less stressful experience for the infants with general anesthesia. With good monitoring postoperatively we can get them through safely.

References:

1. Coté CJ, Zaslavsky A, Downes JJ, Kurth CD, Welborn LG, Warner LO, Malviya SV: Postoperative apnea in former preterm infants after inguinal herniorrhaphy. A combined analysis. Anesthesiology 1995; 82: 809-22
2. Krane EJ, Haberkern CM, Jacobson LE: Postoperative apnea, bradycardia, and oxygen desaturation in formerly premature infants: prospective comparison of spinal and general anesthesia. Anesth Analg 1995; 80: 7-13
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3. Kurth CD, LeBard SE: Association of postoperative apnea, airway obstruction, and hypoxemia in former premature infants. Anesthesiology 1991; 75: 22-6
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4. Kurth CD, Spitzer AR, Broennle AM, Downes JJ: Postoperative apnea in preterm infants. Anesthesiology 1987; 66: 483-8
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5. Malviya S, Swartz J, Lerman J: Are all preterm infants younger than 60 weeks postconceptual age at risk for postanesthetic apnea? Anesthesiology 1993; 78: 1076-81
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6. Warner LO, Teitelbaum DH, Caniano DA, Vanik PE, Martino JD, Servick JD: Inguinal herniorrhaphy in young infants: perianesthetic complications and associated preanesthetic risk factors. Journal of Clinical Anesthesia 1992; 4: 455-61
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7. Welborn LG, De Soto H, Hannallah RS, Fink R, Ruttimann UE, Boeckx R: The use of caffeine in the control of post-anesthetic apnea in former premature infants. Anesthesiology 1988; 68: 796-1006
8. 8. Welborn LG, Hannallah RS, Fink R, Ruttimann UE, Hicks JM: High-dose caffeine suppresses postoperative apnea in former preterm infants. Anesthesiology 1989; 71: 347-9
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9. Welborn LG, Hannallah RS, Luban NLC, Fink R, Ruttimann UE: Anemia and postoperative apnea in former preterm infants. Anesthesiology 1991; 74: 1003-6
10. Welborn LG, Ramirez N, Oh TH, Ruttimann UE, Fink R, Guzzetta P, Epstein BS: Postanesthetic apnea and periodic breathing in infants. Anesthesiology 1986; 65: 658-61
11. Welborn LG, Rice LJ, Hannallah RS, Broadman LM, Ruttimann UE, Fink R: Postoperative apnea in former preterm infants: prospective comparison of spinal and general anesthesia. Anesthesiology 1990; 72: 838-42
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12. Williams JM, Stoddart PA, Williams SAR, Wolf AR: Post-operative recovery after inguinal herniotomy in ex-premature infants: comparison between sevoflurane and spinal anaesthesia. Br J Anaesth 2001; 86: 366-71

ABSTRACT

Post-operative recovery after inguinal herniotomy in ex-premature infants: comparison between sevoflurane and spinal anaesthesia.

AUTHORS:
Williams JM, Stoddart PA, Williams SAR, Wolf AR

SOURCE:
Br J Anaesth 2001; 86: 366-71

ABSTRACT:
No abstract available