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Anaesthesia - post-operative management of ex-premature infants and full-term neonates having anaesthesia

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  1. Gestational age (GA): The number of week's gestation at birth. An infant is considered premature < 37 weeks.
  2. Post-conceptual age (PCA): The gestational age plus natal age in weeks.
  3. Apnoea: Absent breathing for 15 seconds or more, or less than 15 seconds if associated with bradycardia (HR <100bpm) or oxygen saturation <90%.


Ex-premature infants less than 58 week's post-conceptual age (PCA) present a major anaesthetic challenge for procedures commonly performed on a day stay basis in full term infants.

Immaturity of central respiratory control, and/or respiratory obstruction, leads to an increased incidence of apnoea, which may be associated with bradycardia.

Approximately one third of ex-premature infants will develop cardio-respiratory problems following general anaesthesia. Although these mainly occur in recovery, the first apnoea event may not manifest for at least 12 hours following general anaesthesia. Other risk factors include episodes of apnoea at home, anaemia (Hct <0.3), neurological disease and complicated postnatal history.

The precise incidence at different GA, PCA, and clinical status is difficult to quantify, but is inversely related to PCA and to a lesser extent GA. However, published studies allow some prediction, and form the basis of this policy document.

Ex-premature infants less than 44 weeks PCA are particularly at risk, however post anaesthetic apnoea has been described in infants of up to 52 weeks PCA. Best evidence suggests that the incidence of apnoea following anaesthesia progressively reduces to less than 5% at 48 weeks PCA with a GA 35 weeks or 50 weeks PCA with a GA 32 weeks. The incidence reduces to less than 1% at 54 weeks PCA with a GA of 35 weeks minimum, or 56 weeks PCA with a GA of 32 weeks.

Algorithm for elective surgery

Elective surgery flow chart

Regional vs General Anaesthesia

There appears to be no difference in the risk of postoperative apnoea and/or bradycardia between infants who undergo spinal and general anesthesia. Even if regional anesthesia can be used without sedative administration, these patients are at risk for postoperative apnoea and require appropriate postoperative monitoring.

A prospective multi-institutional study randomized infants <58 weeks PCA to regional or general anaesthesia for inguinal herniorrhaphy. Postoperative apnoea occurred in 6.1 percent of ex-premature infants, with no difference between regional and general anaesthesia. Apnoeic episodes in the first 30 minutes in the recovery room were more common with general anaesthesia (3 v 1%). The incidence of apnoea between 30 minutes and 12 hours was the same with regional and general anaesthesia.

Planning a procedure

Where possible, procedures requiring anaesthesia should be delayed until the following milestones are reached:

  • The ex-premature infant is older than 58 weeks PCA,
  • The full term infant older than 44 weeks PCA.

All ex-premature infants less than 58 weeks PCA, and full term infants less than 44 weeks PCA, must be admitted for overnight stay post anaesthesia.

Ex-premature infants booked for day stay procedures must be at least 58 weeks PCA, and full term infants at least 44 weeks PCA. They must fulfill day stay criteria in all respects.

There needs to be clear, early communication between surgeon, anaesthetist, and if applicable, neonatologist/intensivist with regard to the timing and nature of a procedure, and the clinical condition of the patient, so that appropriate post-operative care arrangements can be made at the time of booking. Patients from NICU and PICU will return to the respective unit for post-operative care. A transfer team from NICU will accompany the infant to and from Starship Operating Rooms (OR).

Post-operative management

All ex-premature infants less than 58 weeks PCA and full term infants less than 44 weeks PCA must be continuously monitored for apnoea and bradycardia for at least 12 hours following anaesthesia of any type. Monitoring must be continued for 12 hours after any episode of apnoea or bradycardia, and should include pulse oximetry, heart rate, and apnoea alarm.

The post-operative care facility most suitable for a particular infant will depend on PCA, clinical condition, and nature of the procedure. All patients, with the exception of intubated patients for admission to PICU or NICU, will transfer from the OR to PACU (refer to PACU discharge criteria).

Ex-premature infants less than 44 weeks PCA are particularly at risk of post anaesthetic apnoea, and ex-premature infants 44-58 weeks PCA who have a poor post natal history may also be at high risk of post anaesthetic apnoea. These infants will commonly be managed in the high dependency area and should be discussed with a PICU Specialist with regard to appropriate post-operative care.

Ex-premature infants 44-58 weeks PCA with a good post natal history but who are having major or prolonged surgery, or who require opioid or epidural analgesia, should be admitted to the high dependency on PICU.

Ex-premature infants 44-58 weeks PCA with a good post natal history who are having minor surgery and do not require opioid or epidural analgesia may be admitted to the ward post-operatively, but must be suitably monitored as detailed above, and within easy access of the nursing station.

Any episodes of apnoea or bradycardia should be reported to the surgical team. Prolonged or recurrent apnoea, and apnoea associated with bradycardia or desaturation requires admission of the infant to PICU.

Requirements for postoperative monitoring should be clearly detailed by the anaesthetist in the patient's notes.


  1. Steward DJ: Preterm infants are more prone to complications following minor surgery than are term infants. Anesthesiology 56: 304-306, 1982
  2. Malviya S, Swartz J, Lerman J. Are all preterm infants younger than 60 weeks post conceptual age at risk for post anesthetic apnea? Anesthesiology. 1993 Jun; 78(6):1076-81.
  3. Cote CJ, Zaslavsky A, Downes JJ et al. Postoperative Apnea in former premature infants after inguinal herniorrhaphy. Anesthesiology 82:809-822, 1995
  4. Somri M et al. Postoperative outcome in high-risk infants undergoing herniorrhaphy: comparison between spinal and general anaesthesia. Anaesthesia. 1998 Aug; 53(8): 762-6
  5. Davidson AJ et al. Apnea after Awake Regional and General Anesthesia in Infants: The General Anesthesia Compared to Spinal Anesthesia Study--Comparing Apnea and Neurodevelopmental Outcomes, a Randomized Controlled Trial.. General Anesthesia compared to Spinal anesthesia. (GAS) Consortium. Anesthesiology. 2015; 123(1):38.
  6. Jones LJ et al. Regional (spinal, epidural, caudal) versus general anaesthesia in preterm infants undergoing inguinal herniorrhaphy in early infancy. Cochrane Database Syst Rev. 2015

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Document Control

  • Date last published: 30 January 2019
  • Document type: Clinical Guideline
  • Services responsible: Paediatric Anaesthesia
  • Author(s): P Wolstencroft, Niall Wilton
  • Owner: Niall Wilton
  • Editor: Michael Tan
  • Review frequency: 2 years

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