CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP) BY: NICOLE STEVENS

DEFINITION  A gas pressure higher than atmospheric pressure, continuously applied to the airway during spontaneous breathing. It is provided to help maintain functional residual capacity (FRC) and prevent airway collapse, thereby reducing work of breathing and improving gas exchange.  CPAP can be delivered by a neopuff (mask or cut down ETT), through a ventilator or via a bubbler system

Pathophysiology  Early management with CPAP can prevent or compensate for the increased alveolar-retraction forces that are a consequence of high surface tension caused by deficiency of surfactant  Surfactant is produced by the type II pneumocytes in the alveolar walls, production of it can be promoted by distention, or stretching of the alveolar  There is evidence to support, and continuing studies being done to look at the benefits of a combination of CPAP and early surfactant administration. The aim is to prevent the need for, or minimise the ventilatory support given (in length of time and required pressures).

Circuits and interfacing  Most centres use the Fisher and Paykel ventilator and CPAP circuits. The interfacing connected to this varies from centre to centre.  2 most common are the Hudson prongs and the F&P midline mask or prongs.

Other equipment  With both the Hudson prongs and the F&P systems other equipment is also required.  Both systems have a particular hat that is placed on the baby and used to hold the tubing/prongs in the correct position.  When caring for a baby on CPAP it is important to have a neopuff at hand, suction equipment and appropriate monitoring in place.

Canberra Hat and Hudson prongs

Settings  Set gas flow for ventilator at 6-8 litres/min  Set gas flow for bubble circuit at 5-10 litres/min (aiming for a flow that achieves a moderate ‘boil’ in the water chamber)  PEEP is ordered by a medical officer and will usually be between 5 – 8cm/H2O (occassionally PEEPs as high as 10cm/H2O may be used in a tertiary hospital in extreme cases where reintubation is very undesirable).

Process  Measure head for hat size  Measure nares for prong/mask size if using F&P; examine nares and judge by weight if using Hudson prongs  Put equipment together, test circuit for leaks by turning on, occlude prongs (to close the circuit) and observe if the chamber bubbles, if not trouble shoot the circuit to look for breaks in the circuit

Process cont…  Position baby on the back  Apply hat  Insert prongs/position mask  Secure tubing/prongs  Using 2 people turn babies head to the side and hold in position ensuring prongs and tubing stay straight; other person rotates body and pulls arm through on underside. Baby will now be prone with one hand up to the mouth and the other lying down beside the body.  Use gel pillows and neck rolls (cloth nappies) to assist with comfortable positioning.

Process cont….  NGT or OGT required to be in place; for smaller/premature babies always use an OGT when babies are on CPAP; if it is a larger/term baby may be able to use a NGT (it is about the size of the nares and ability to comfortably fit prongs and gastric tube in the one nare).  Tube needs to be opened to air, to allow excess air to ‘vent’ out; in addition aspirate tube at least 6 hrly and discard excess air.

CARES  Cluster cares (6 – 8hrly); coordinate with any procedures that may need to happen (eg. CXR, blood tests, IV resites)  Cares consists of a nappy change, temperature taking, removal of hat and prongs/mask to inspect for pressure areas, suction nares/mouth if required, reapply hat and prongs and reposition  If baby very dependent on PEEP can use the neopuff and mask during cares; if baby on oxygen can use cot oxygen to deliver same FiO2 via ambient cot O2 while CPAP is off.  Depends on the baby as to how much time you can take  Preferable to use 2 people if you are not feeling 100% confident or if the baby is quite unstable

Cares cont…  Visually check position of prongs at least hourly, ensuring the nose is not distorted and no pressure is being applied to the nasal septum by the prongs; maintain a small gap between the prongs and the septum; if using a mask inspect for pressure areas across the nasal bridge  Use a skin/nasal integrity chart to record shift by shift observations

Observations  Record hrly: PEEP, flow, FiO2, humidifier temperature, SaO2, HR, RR  Check temperature hrly for 4 hours when starting or stopping CPAP (because of additional heat created by hat and humidified tubing), otherwise check temp 4 – 6 hourly if stable  Measure blood pressure initially and then at least daily while on CPAP  Nasal integrity chart each shift  Record any apnoeic episodes, desaturations and/or bradycardias requiring intervention

Commencing CPAP  Used for babies with RDS (displaying symptoms such as: tachypnoea, grunting, rib recession), and having an oxygen requirement  Recommended by NETS to commence at CPAP of 7cm/H20

When to increase PEEP  If, for example, a baby is on a CPAP of 5, has significant work of breathing and has an increasing oxygen requirement (greater than 30%) increase the PEEP to 6. Same for steps up to PEEPs of 7 and 8.  Baby in a PEEP of 8 still with significant work of breathing and oxygen requirement may require intubation and surfactant administration  Always be aware of risk of air leak and consider CXR if baby clinically deteriorating.

When to wean CPAP  Respiratory rate consistently < 70 br/min  FiO2 < 25%  Work of breathing reduced  Wean by 1 cm H2O every 2 – 4 hrs (recommend slower the more premature the baby)  Trial off CPAP once baby has been stable at CPAP of 5cm for several hours and in < 25% oxygen

Complications  Pneumothorax  Agitation  Continued deterioration  Nasal trauma

Nutrition  Babies on CPAP in acute phase of RDS should be kept NBM  Commence IV fluids at 60mL/kg/day  Once RR < 70 br/min, FiO2 < 25%, and work of breathing has settled commence enteral feeds cautiously (eg at about 15mL/kg/day via gastric tube)  Grade up feeds as tolerated  If unable to commence feeds by 96 hrs of age parenteral nutrition is usually required, so transfer to a tertiary hospital would be recommended.

References  Verder, H., Robertson, B., Greisen, G., Ebbesen, F., Albertsen, P., Lundstrom, K. & Jacobsen, T. (1994). Surfactant therapy and nasal continuous positive airway pressure for newborns with respiratory distress syndrome. New England Journal of Medicine. Vol. 331, No. 16 pp –  The Royal Womens Hospital Policy, guideline and procedure manual “Continuous positive airway pressure via hudson cannula” (last updated 2010)  Guideline for administration of nasal CPAP in Victorian non-tertiary Level 2 nurseries (2012). Edited by Dr. Michael Stewart, Dr. Carl Kuschel & Fay Prestbury.