Is It Safe to Eliminate CO2 Monitoring for IV PCA After Administering Neuraxial Opioids for C-section?

Steve Lysak, MD; Katherine W. Arendt, MD

Q Is It Safe to Eliminate CO2 Monitoring for IV PCA After Administering Neuraxial Opioids for C-section?

Dear Q&A,

We have a major OB section with over 6,000 deliveries per year. The OB Department has requested IV PCA after neuraxial opioids for C-section patients. Our current regimen is 0.15 spinal Astramorph or 2 mg epidural Astramorph.
For breakthrough pain, we have started IV PCA utilizing on-demand opioids (no continuous) with end tidal CO2 monitoring. The OB Department feels this is uncalled for and increases patient complaints.

Any thoughts or literature on IV PCA opioids post neuraxial opioids for C-section and appropriate monitoring. We currently maintain 24 hours of every hour clinical nursing evaluations and had tried Stadol and Nubain in the past, both of which are increasingly unavailable.

Bottom line question: Safety of eliminating CO2 monitoring for IV PCA after administering the neuraxial opioids for C-section?

Steve Lysak, MD
Greenville Anesthesiology PA

A Dear Dr. Lysak,

This is an excellent question. It touches on a number of controversial and interesting safety topics in obstetric anesthesiology. Specifically, 1) appropriate ventilation monitoring with the use of long-acting neuraxial opioids or intravenous PCA opioids for postoperative pain, and 2) the concomitant use of a long-acting neuraxial opioid and a long- or short-acting intravenous (IV) opioid via a PCA device for the treatment of acute postoperative pain.

First, Dr. Lysak, your team is absolutely correct to insist on additional monitoring beyond pulse oximetry, or additional nursing assessments to assess ventilation when either long-acting neuraxial opioids or intravenous PCA opioids are used. This would especially be true if patients are utilizing both opioid modalities. Postoperative hypoventilation is becoming the leading cause of anesthesia-related maternal mortality.1,2 With increasing rates of maternal obesity, our risk for postoperative hypoventilation in our postpartum mothers may only get worse.

The Practice Guidelines for the Prevention, Detection, and Management of Respiratory Depression Associated with Neuraxial Opioid Administration, by the ASA Task Force on Neuraxial Opioids recommend, “All patients receiving neuraxial opioids should be monitored for adequacy of ventilation (e.g., respiratory rate, depth of respiration [assessed without disturbing a sleeping patient]), oxygenation (e.g., pulse oximetry when appropriate), and level of consciousness.”1 The APSF, however, sets more challenging monitoring goals with the publication of the conclusions and recommendations of a June 8, 2011 APSF forum entitled, “Essential Monitoring Strategies to Detect Clinically Significant Drug-Induced Respiratory Depression in the Postoperative Period.”4 These recommendations seem to imply that we should provide ventilation monitoring for most of our postpartum patients who receive long-acting neuraxial opioid. However, they only specifically state that ventilation monitoring is indicated “when supplemental oxygen is needed to maintain acceptable oxygen saturations,” which is rare in postpartum women.

With the current state of the art of postoperative ventilation monitoring, it is expensive and, for many hospitals, impossible to provide ETCO2 ventilation monitoring on every postpartum patient that receives long-acting neuraxial and/or intravenous opioids. Until this technology advances, rigorous nursing assessments may have to be a reasonable substitute. At Mayo Clinic in Rochester, Minnesota, I believe we provide some of the most conservative postcesarean delivery monitoring in the country. We have our nursing staff obtain Richmond Agitation Sedation Scale (RASS) scores every hour for the first 12 hours and every-other-hour for the next 12. Pulse oximetry is continuous. Note, that the night time “wake up” that’s required to get the RASS score is disliked by the nurses, patients, and the obstetric service. However, until we have more reliable, comfortable, and cheaper continuous ETCO2 monitoring, it seems sedation monitoring may be the most reasonable alternative.

Second, Dr. Lysak, regarding your PCA question, I believe that it may be prudent to avoid the use of a long-acting neuraxial opioid with long-acting intravenous opioids in most postcesarean delivery patients. With the potential for delayed respiratory depression from the long-acting neuraxial opioid, a long-acting intravenous opioid could potentially increase the risk of respiratory depression sneaking up on our patients during the night. Therefore, if a PCA device is added for additional opioid administration, a low-dose fentanyl PCA may be safest.

Here at Mayo we do occasionally add a fentanyl PCA for postcesarean delivery patients typically starting at 10 mcg every 10 minutes with a 4-hour lock-out of 200 mcg, we increase this to 20 mcg every 10 minutes with a lock-out of 400 mcg if necessary. Note, however, that we have recently changed our routine postcesarean pain management to a multimodal regimen of oral oxycodone and scheduled acetaminophen and ketorolac eventually converting to ibuprofen. This has been a very successful practice change for us, largely eliminating our patients’ needs for fentanyl PCAs. Patients are describing decreased pain, nursing is describing decreased opioid side-effects and greater patient function, and administration is anticipating much expense saved with the reduced use of pricey fentanyl PCAs. I would ask your obstetric team if their postcesarean pain regimen involves scheduled acetaminophen and NSAID administration. You can support this request by informing them that such practice is recommended in the Practice Guidelines for Acute Pain Management in the Perioperative Setting from the ASA Task Force on Acute Pain Management.5

Your question is excellent. I hope I was able to provide a few insights to help you keep your new mothers safe.

Dr. Katherine Arendt

Katherine W. Arendt, MD
Consultant, Department of Anesthesiology
Assistant Professor of Anesthesiology
College of Medicine
Mayo Clinic
Rochester, MN


  1. 1. Mhyre JM, et al. A series of anesthesia-related maternal deaths in Michigan, 1985-2003. Anesthesiology 2007;106:1096-104.
  2. Cooper GM, McClure JH. Anaesthesia chapter from Saving Mothers’ Lives; reviewing maternal deaths to make pregnancy safer. Br J Anaesth 2008;100:17-22.
  3. ASA Task Force on Neuraxial Opioids. Practice Guidelines for the Prevention, Detection and Management of Respiratory Depression Associated with Neuraxial Opioid Administration. Anesthesiology 2009;110:218-30.
  4. Stoelting RK, Overdyk FJ. Essential Monitoring Strategies to Detect Clinically Significant Drug-Induced Respiratory Depression in the Postoperative Period: Conclusions and Recommendations. Accessed 8/1/2013
  5. ASA Task Force on Acute Pain Management. Practice Guidelines for Acute Pain Management in the Perioperative Setting. Anesthesiology 2012;116:248-73.

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