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This Guideline is relevant to all neonatal units managing preterm infants in the West of Scotland. Users should also refer to the West of Scotland guidelines for respiratory support of the preterm infant and for Intubation and premedication. They should also refer to the Neonatal pharmacy monographs for all of the medications used.
Preterm infants commonly develop respiratory distress syndrome (RDS) requiring some form of respiratory support and potentially surfactant administration1. Treatment with surfactant has been shown to reduce the risk of death and bronchopulmonary dysplasia (BPD) in preterm infants; however the standard approach to administering surfactant involves using an endo-tracheal tube and a period of mechanical ventilation (MV)2. It is well known that MV causes damage to the fragile preterm lungs so many lung protective strategies for respiratory management and ventilation have been developed.
As per our current guideline on the respiratory management of preterm infants the preferred initial management is using primary CPAP with the use of rescue surfactant for infants with an increasing oxygen requirement. To reduce the need for MV but still deliver surfactant several less invasive techniques have been developed. One of these techniques is called LISA and is the process of delivering surfactant directly into the lungs via a fine bore catheter inserted into the trachea3. In a recent review by Wu et al4, LISA technique was associated with a significant reduction in the risk of mechanical ventilation within 72hours and bronchopulmonary dysplasia at 36 weeks compared to other strategies of surfactant administration (p<0.00001). These findings have been also been seen in a meta-analysis by Isayama et al in 20151 and most recently by Aldana-Aguirre et al who found a lesser need for MV and a reduction in the composite outcome of death or BPD at 36 weeks compared to INSURE (p 0.01)2.
Infants who are suitable to be considered for LISA are those being managed with primary CPAP or High Flow with evidence of increasing respiratory distress and with a rising oxygen requirement. The latest European consensus guidelines suggest treating infants <26 weeks gestation when their oxygen requirement increases above 30% and those ≥ 26 weeks with an oxygen requirement of greater than 40%5. Recent evidence suggests that the threshold of fiO2 of 30% should be used for all infants <32 weeks gestation to reduce complications in untreated RDS6. While this technique is still relatively new, it is advisable that it is performed under the controlled environment within neonatal intensive care rather than in the delivery room. The infant’s oxygen requirement should be persistent despite a period of minimal handling.
Preparation for LISA is very similar to that for elective intubation. The infant should be positioned as if for intubation and swaddled for comfort. It is important that the baby has continuous monitoring of heart rate and oxygen saturations. They should have an orogastric tube in-situ and the stomach should be aspirated. The baby should have intravenous access which has been confirmed to be working. It is important to maintain the baby’s temperature throughout the procedure. Ensure that the infant has been commenced on appropriate dose of caffeine citrate and dose given at least 30minutes prior to procedure.
A neopuff or self inflating bag and appropriate sized mask should be available as well as appropriately sized endotracheal tubes should the procedure have to be abandoned due to persistent hypoxaemia, bradycardia or apnoea. Surfactant should be drawn into a 5ml syringe, with additional air, to be delivered through the cords via a LISA catheter. Where available, a video laryngoscope can be used to guide the insertion of the LISA catheter. This gives opportunity for correct placement of the catheter through the vocal cords to be confirmed by an assistant. However should a video laryngoscope not be available, or the operator not be comfortable or experienced with the use of the video laryngoscope and are confident with direct laryngoscopy then a standard laryngoscope can be used.
CPAP or High Flow should be maintained throughout the procedure. In some instances the CPAP prongs may obscure the view for laryngoscopy so for the duration of the procedure the infant may need to be managed on High Flow.
No RCT’s have looked at the use of premedication for LISA but expert opinion suggests that premedication may be considered. It is known that laryngoscopy may cause adverse physiological responses including systemic, pulmonary and intracranial hypertension and bradycardia, but with the use of a premed these effects as well as pain and discomfort can be reduced. A retrospective review by Dekker et al showed there was improved comfort during LISA when sedation was given (p = 0.002), however there was a slight trend to more ventilation when it was used7. Some practices are to give ‘awake sedation’ with naloxone available should there be opiate induced apnoea or shallow breathing8. Atropine should also be available to be given in instances of prolonged bradycardia.
The operator may elect to give Atropine electively prior to the procedure. NB – If atropine is used, staff should be aware of the possibility of urinary retention – see monograph
LISA should be performed by or supervised by staff members who have been trained in how to carry out the procedure and who are competent at intubation. The video laryngoscope, where the operator is comfortable with its use, may be used for LISA procedures to assist in accurate positioning of the LISA catheter. Following administration of the fentanyl direct laryngoscopy should be performed and the LISA catheter inserted through the vocal cords to the desired length, 1.5cm for infants < 27 weeks gestation and 2cm for infants ≥ 27 weeks gestation. Occasionally McGills forceps may be required to place catheter through the cords. Once the catheter is seen passing through the cords the laryngoscope should be withdrawn while ensuring the catheter remains in-situ, taking note of the marking on the catheter which is at the lips. The mouth is then held shut to maintain CPAP and the head returned to a neutral position. The surfactant is slowly injected into the catheter over 3-5 minutes to minimise apnoea / bradycardia. If there is prolonged hypoxia or bradycardia the rate of surfactant administration should be reduced. FiO2 should be titrated to keep oxygen saturation between 89 and 95% . If there is persistent bradycardia atropine should be administered. If the baby becomes apnoeic or has persistently shallow breathing despite gentle stimulation, thought to be secondary to the sedation, a dose of naloxone should be given. If despite this or at anytime the baby has prolonged bradycardia, hypoxia or is apnoeic the procedure should be stopped and the baby given positive pressure ventilation plus or minus intubation.
Following administration of surfactant the baby should be nursed prone on nasal CPAP or Duopap in an incubator. If the procedure has been successful there should be a marked reduction in oxygen requirement within minutes to hours of the procedure. If the baby develops an increasing oxygen requirement, a pneumothorax should be excluded. A further dose of surfactant should be considered. This could be administered by LISA if they do not meet any of the contra-indications, however if they have marked work of breathing, a persistently high oxygen requirement, a respiratory acidosis or severe RDS on chest x-ray they should be intubated and ventilated prior to the repeat dose of surfactant.
This is a new procedure being carried out in the unit and it is important to record how the babies who we perform this on tolerate the procedure and manage post procedure. Please complete an audit data collection form following completion of the procedure.
Last reviewed: 26 October 2018
Next review: 01 November 2021
Author(s): Dr Carolyn Abernethy – Neonatal Consultant PRM
Co-Author(s): Other Professionals Consulted: Dr Joyce O’Shea – Neonatal Consultant RHC; Dr Nikolaus Kau – Neonatal Consultant Aberdeen
Approved By: MCN for Neonatology West of Scotland