Episode #273 Breathless Moments: When Premature Babies Need Extra Vigilance

Hello and welcome back to the Anesthesia Patient Safety Podcast. My name is Alli Bechtel, and I am your host. Thank you for joining us for another show. We are continuing to cover the excellent articles from the June 2025 APSF Newsletter. Today, we are talking about keep our littlest patients safe during anesthesia care.

Before we dive further into the episode today, we’d like to recognize Fresenius Kabi, a major corporate supporter of APSF. Fresenius Kabi has generously provided unrestricted support to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Fresenius Kabi – we wouldn’t be able to do all that we do without you!”

Our featured article today is “Postoperative Apnea and Former Preterm Infant: Evolving Evidence for Management” by Ying Eva Lu-Boettcher and colleagues. To follow along with us, head over to APSF.org and click on the Newsletter heading. First one down is the current issue and then scroll down until you get to our featured article today. You can also find the June 2025 APSF Newsletter in the Newsletter archives. Don’t worry I will include a link in the show notes as well.

To help kick off the show today, we are going to hear from one of the authors. Here she is now.

[Lu-Boettcher] “ Hi, my name is Eva Lu-Boettcher, a pediatric anesthesiologist at the University of Wisconsin in the United States. I’m currently the Associate Vice Chair for quality and safety within the Department of Anesthesia.”

[Bechtel] We are welcoming Lu-Boettcher back to the podcast. You might remember her from Episode #247, “Nudge Your Way to Greener Pediatric Anesthesia.” If you haven’t listened to that episode yet, we hope that you will check it out especially if you are interested in learning more about safe and sustainable anesthesia care. For our current featured article, I asked Lu-Boettcher why she wrote this article. Let’s take a listen to what she had to say.

[Lu-Boettcher] “ Postoperative apnea is a critical concern for our anesthesiologists, particularly in ex premature and high risk infants due to the interplay of immature respiratory control, anesthetic pharmacodynamics, and the life-threatening implications of undetected apnea events. Understanding and anticipating a postoperative apnea informs key anesthetic decisions and directly impacts patient safety.

The evidence for post-operative admission in ex premature infants, particularly for apnea monitoring and admissions is evolving. I am hoping that this article helps summarize recent evidence and help our anesthesia communities make informed decisions.”

[Bechtel] Thank you so much to Lu-Boettcher for helping to introduce this topic. And now its time to get into the article. Let’s start with some important definitions.

Premature or preterm infants are infants born at gestational age less than 37 weeks. Apnea of prematurity occurs in premature or preterm infants and involves a respiratory pause for more than 15-20 seconds or shorter respiratory pauses that are accompanied by oxygen desaturation or bradycardia with a heart rate of less than 100BPM. An important consideration is that the inverse of apnea is inversely correlated with gestational age. A study of preterm and premature infants found that almost all infants born at 28 weeks or less gestation had recurrent apnea while the incidence decreased to 85% for infants born at 30 weeks and it was down to 20% for infants born at 34 weeks gestation. We know that preterm and former preterm infants are at increased risk for postoperative apnea, but there are inconsistent definitions for apnea, desaturation, and bradycardia which means that we do not know the true incidence. As a result, monitoring protocols are different across institutions. What is the monitoring protocol at your institution for preterm or former preterm infants undergoing anesthesia?

While you are checking on that protocol, let’s talk a little more about postoperative apnea in our youngest patients. Apnea of prematurity occurs due to immature development of the respiratory control centers with respiratory and chemoreceptors that are less likely to respond to changes in the postnatal environment. This means that premature infants have an initial increase in respiratory rate and volume in response to hypoxia followed by a sustained decline in ventilation. When premature infants experience hypercapnia, the first response is an increase in ventilation by prolonging expiration time without an increase in respiratory rate or overall tidal volume leading to a lower minute ventilation than in term infants.

This is a problem of a combination of central and obstructive pathophysiology. When premature infants experience airway obstruction, it is more likely that the response involves apnea and periodic breathing, but this response decreases with increasing post menstrual age, which you can calculate as the gestational age + postnatal age. General anesthesia leads to a decrease in upper airway tone and an increased risk for airway obstruction which may lead to postoperative apnea. Risk factors for postoperative apnea include the following:

• cardiac shunts
• anemia
• decreasing gestational age
• hypothermia
• glucose and electrolyte disturbances
• patent ductus arteriosus

Anesthesia professionals need to remain vigilant since premature infants have a much higher risk for cardiopulmonary complications in the immediate postoperative period compared to term infants. Let’s look at the literature where you will see this population categorized based on post conceptual age. If we look back at early prospective studies from the 1990’s, about 20-30% of otherwise healthy former pre-term infants under 60 weeks post conceptual age experienced postoperative apnea following general anaesthesia. We’re going to take a closer look at the 1995 study by Coté and colleagues, “Postoperative apnea in former preterm infant.” Check out the show notes for the citation. The investigators looked at 8 studies of former preterm infants undergoing inguinal hernia repair. Here are some of the results:

• A combined apnea rate of about 25% with variation between 5-49%. This variability was due to apnea detection monitoring.
• The majority of apnea events were detecting by pneumogram-diagnosed and occurred in infants less than 44 weeks PCA with a history of anemia which was an independent risk factor.
• The incidence of postoperative apnea in preterm infants was inversely related to the infants gestational age and post conceptual age at the time of anaesthesia.
• Postoperative apnea decreased to less than 1% at 54 weeks PCA in infants with gestational age of 35 weeks and at 56 weeks PCA for infants with gestational age of 32 weeks.

Check out Figure 1 in the article for a picture of the predicted probability of postoperative apnea depending on the postconceptual age for all patients for each investigator of the 8 studies.

The APSF authors did the homework for us and have summarized the findings of this study and other reports that showed that infants less than 45 weeks PCA were more likely to develop postoperative apnea. For older infants between 46-60 weeks PCA, you need to evaluate their comorbidities which will influence their risk for apnea. These comorbidities include the following:

Necrotizing enterocolitis

Bronchopulmonary dysplasia

Former apnea episodes

Anosmia

And lower birth weight.

Due to these findings, it has been recommended that infants between 46-60 weeks PCA should be monitored for 12 hours postoperative and respiratory monitoring is recommended for patients with a history of apnea episodes, chronic lung disease, neurological disease, or anemia. A high-risk time for apnea for infants who underwent general anaesthesia is in the first 30 minutes postop and these episodes are more likely to require significant intervention rather than just tactile stimulation. Late apnea is just as likely to occur in infants who received general or regional anaesthesia.

It’s time to look at the clock and talk about the timing of postoperative apnea. Studies have shown a variety of results with first apnoeic episodes occurring as early as 2 hours after surgery or even up to 12 hours after surgery. There is a 1993 article in Anesthesiology by Malviya and colleagues that asked the important questions, “Are all preterm infants younger than 60 weeks post conceptual age at risk for postanaesthetic apnea?” This was a prospective study of 91 infants younger than 60 weeks post conceptual age who underwent 101 general anaesthetics. All of the infants had cardiorespiratory monitoring overnight and comorbidities were determined by a review of medical records and history. The investigators found that the first episode of postop apnea or bradycardia occurred within 12 hours after surgery. The authors concluded that ex-preterm infants younger than 44 weeks PCA are at the greatest risk for apnea after general anaesthesia when compared to older infants. I will include the citation in the show notes for more information.

There are reports of recurrent apnoeic events that may occur up to 72 hours postoperatively so longer monitoring may be required for some infants.

Let’s check out Table 1 in the article for a review of postoperative admission and observation recommendations based on the current available literature.

Keep in mind that patients who are term or preterm or former preterm and under 60 weeks PCA should be considered for postoperative monitoring and an observation period. Monitoring should include apnea and bradycardia monitoring, nursing observations, continuous pulse oximetry, and a respiratory monitor.

Here are some of the preterm recommendations:

• Former preterm infants < 55 weeks PCA should be admitted postoperatively.⁶
• Former preterm infants < 60 weeks PCA with risk factors for postoperative apnea should be admitted and observed for a minimum of 12 hours.¹⁵
• Former preterm infants who are > 55 and < 60 weeks PCA without anemia, apnea, or other risk factors can be observed postoperatively for 6 hours and then later discharged if no events occur.⁶
• All infants should have been apnea-free for 12 hours prior to discharge.
• Postoperative apnea in former preterm infants > 60 weeks PCA has not been reported—the most conservative approach would be to admit any premature infant under 60 weeks PCA.⁶

Next, let’s look at recommendations for term infants which include the following:

• Term infants < 44 weeks PCA should be admitted postoperatively and must remain apnea-free for 12 hours prior to discharge.²⁴
• Any term infant should be monitored for a minimum of 2 hours post-anesthetic and be discharged only with uneventful postop course.
• All patients < 6 months who receive opioids should be monitored for a minimum of 2 hours and may require admission depending on complexity and duration of the procedure.
• Term infants with a history of bradycardia and apneas, or those with a sibling with Sudden Infant Death Syndrome, should be considered for admission.⁶
• Term infants > 30 days but less than 6 months old can be discharged based on attending anesthesiologist discretion if without comorbidities or postoperative complications.

This is a lot to remember, but Table 1 serves as an excellent resource that you can refer to the next time you are preparing to take care of our smallest and youngest patients. I will include this table in the show notes as well. The APSF authors support that despite the variability from different studies, a 12-hour apnea free period is likely safe for discharge planning. Keep in mind that patients who receive spinal or caudal anesthesia may have a decreased risk for early apnea, but they are still at risk for late apnea which may be due to the residual depressant effects of the general anesthetics.

There is a lot of variability in policies for postoperative monitoring depending on the institution which may be due to the variability in the literature that we have seen. We need to remember that these often included smaller studies and the variable incidence of these events.

Going forward, we hope to see a detailed analysis from a much larger data set and drumroll please…

[drumroll sound effect]

This is happening right now and we are looking forward to results from a meta-analysis and micro-analysis in the near future. So, stay tuned!!

Before we wrap up for today, we are going to hear from Lu-Boettcher again. Speaking of the future, I also asked her what she envisions for the future when it comes to postoperative apnea in former preterm infants. Here is her response.

[Lu-Boettcher] “ Although numerous pediatric surgical centers have established admissions guidelines for former preterm infants after anesthesia, these protocols vary across institutions. This variability is partly explained by limited sample sizes and findings regarding postoperative apnea. In prior studies, current initiatives are focused on gathering data with and micro analysis that are underway.

These efforts are expected to inform new guidelines for the postoperative management of this vulnerable population, so there’s more to come.”

[Bechtel] Thank you so much to Lu-Boettcher for contributing to the show today. We love talking about guidelines and recommendations on this show so we cannot wait to learn more about this in the future so that we can continue to keep these patients safe during and after anesthesia care.

If you have any questions or comments from today’s show, please email us at [email protected]. Please keep in mind that the information in this show is provided for informational purposes only and does not constitute medical or legal advice. We hope that you will visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today.

The APSF Newsletter is the official journal of the Anesthesia Patient Safety Foundation. Readers include anesthesia professionals, perioperative providers, key industry representatives, and risk managers. It is free of charge and available in a digital format with a focus on anesthesia-related perioperative patient safety issues. The 40^th Anniversary of the APSF Newsletter is right around the corner and we will have a special newsletter publication!! That’s right. All new articles, the latest in perioperative patient safety, and more ways for you to help to keep yourself and your patients safe!

Until next time, stay vigilant so that no one shall be harmed by anesthesia care.

© 2025, The Anesthesia Patient Safety Foundation