To the Editor:—

I read with pleasure Dr. Eisenach’s concise review of a controversial topic: combined spinal–epidural (CSE) analgesia for labor. 1Because my scientific and clinical interests are situated in obstetric anesthesia, I would like to make some comments on this excellent contribution. First, I would like to point out a typographical error: not 5–10 mg  sufentanil and 20–35 mg  fentanyl are used in obstetrics, but 5–10 μg  and 20–35 μg .

Second, hypotension is a complication of CSE in labor. However, it is not limited to this technique alone. Various studies demonstrated that the incidence and severity of hypotension with CSE is comparable to that of epidural analgesia. 2 

As a result of my clinical experience, I agree that the association between spinal opioids and transient fetal bradycardia is a real problem. The problem has only been addressed in case reports and small studies, making interpretation of data difficult. Future work should provide answers to the following questions:

  • 1. What is the clinical relevance of fetal bradycardia? Thus far it has never resulted in urgent cesarean sections or adverse neonatal outcome.

  • 2. Was fetal distress present before the CSE was performed? All previous studies did not record fetal heart rate and uterine activity immediately before analgesia. Shouldn’t we conduct randomized and blinded studies to establish whether there is an issue at all?

  • 3. Why does CSE using local anesthetics not result in fetal bradycardia if the proposed mechanism of a β-adrenergic “break” is true?

  • 4. Should we avoid spinal opioids in cases with fetal distress or uterine hyperactivity already present before analgesia?

Dr. Eisenach mentioned that respiratory depression occurs in up to 0.1% of patients. To my knowledge, the incidence and severity of this problem was never studied in patients undergoing CSE analgesia for labor. Undoubtedly, we should be cautious when administering intrathecal opioids. Based on dose–response studies, the usual dose of 10 μg sufentanil or 25 μg fentanyl is unnecessarily high. 3,4Most case reports of severe respiratory depression are on small obstetric patients (< 155 cm) who had received 10 μg of sufentanil and had previously received intravenous opioids.

Although CSE is particularly suited in late labor and for ambulation during labor (and the technique of choice in my opinion), I disagree with Dr. Eisenach that this technique is reserved to these specific settings. In our teaching hospital, the majority of cases that require labor pain relief (we have a > 70% rate of neuraxial pain relief) are performed using CSE (> 90%). For several reasons, we have replaced epidural analgesia as our technique of choice. Complications are rare (as frequent as with epidurals) and usually easily treated. CSE performs better in late labor and mobile labor pain relief. However, to ascertain sufficient experience to reliably perform the technique, it should be routinely used both by residents and staff anesthetists. Recent data in the literature (and we have similar results when analyzing our anesthesia charts) suggest that epidural catheters inserted when using a CSE technique have a higher success rate then those inserted after an epidural. 5 

Therefore, I believe that the conclusion should be: CSE analgesia for labor is the technique of choice in certain specific situations and in experienced hands can be safely and successfully used in every laboring parturient.

Eisenach JC: Combined spinal–epidural analgesia in obstetrics. A NESTHESIOLOGY 1999; 91:299–302
Collis RE, Davies DWL, Aveling W: Randomised comparison of combined spinal-epidural and standard epidural analgesia in labour. Lancet 1995; 345:1413–6
Arkoosh VA, Cooper M, Norris MC, Boxer L, Farouz F, Silverman NS, Huffnagle J, Huffnagle S, Leighton BL: Intrathecal sufentanil dose response in nulliparous patients. A NESTHESIOLOGY 1998; 89:364–70
Palmer GM, Cork RC, Hays R, Van Maren G, Alves D: The dose–response relation of intrathecal fentanyl for labor analgesia. A NESTHESIOLOGY 1998; 88:355–61
Eappen S, Blinn A, Segan S: Incidence of epidural catheter replacement in parturients: a retrospective chart review. Int J Obstet Anesth 1998; 7:220–5