Continuous negative pressure (CNEP)
Used in conditions with increased work of breathing, small airways disease, V/Q mismatching and those infants who may tire easily post extubation.
This mode of support can be easily adjusted/manipulated to suit the individual patients – requirements. Start your CNEP roughly 2cms H2O more than you would CPAP. This level is then adjusted until the increase work of breathing decreases. This will be noted with decreased recession, use of expiratory muscles, metabolic acidosis, stable or falling CO2 and improved oxygenation.
The air within the cuirass can cause the infants to be at risk of temperature loss. It is advisable to dress them in pyjamas or warm clothes, without buttons as these can affect the seal on the cuirass or place them under a radiant heater.
Once a suitable level of CNEP is found and the patient is n the recovery phase of their illness weaning from CNEP can be initiated by bringing down the level of CNEP and then once at an expectable level taking the patient off for controlled periods. These are gradual lengthened to suit the patient.
CNEP helps improve right ventricular function, especially when used in conjunction to PPV. References: 10, 11, 12, 13, 15.
There are 3 different Ventilation modes available on the Hayek RTX.
There are 2 modes which are triggered by the patient’s respiratory effort, where are “Respiratory Triggered” and “Respiratory Synchronized”. These modes can be used as pressure support modes and an aid to weaning.
This mode provides full control over the patient’s respiration
- Mandatory respiratory rate is set and delivered; patients do not fight against the mandatory breaths as the Hayek RTX uses their own respiratory muscles to breath. This is a unique function of the Hayek RTX as it mimics physiological respiration.
- Controls both inspiratory and expiratory phases and you have control over the I:E ratio
- Commence rate at 2 above their own current spontaneous rate, then can slowly decrease the rate as patients breathing controlled by Hayek RTX
- If PaCO2 increases alter I:E ratio to 1:1.2 – 1:1.5
- At frequency’ s over 60 the inspiratory pressure and the expiratory pressures should set at the same figures i.e. -15 and +15
- At frequencies of 240-1200 cpm you can only preset frequency and inspiratory pressure parameters
- It is in this mode that you are able to oscillate the patient from 1-20Hz with pressures up to +/- 50 cmH2O
- Provides triggered ventilation with the respiratory cycle triggered by the patient’ s actual respiratory requirements
- The frequency is determined by either the patient’s rate or the minimum frequency set by the physician
- The I:E ratio is determined and set by the physician
- The trigger can either be through the cuirass or through the airway tube placed at or near the patient’s airway e.g. by the patient’s nose or mouth. Cuirass trigger will pick up more vigorous spontaneous breathing, whereas airway mode can be triggered by smaller, shallower respiratory effort.
- As the respiratory cycle is triggered by the patient’s own respiration, this allows better adjustment to the patient’s actual requirements. The respirator will wait for a period for the trigger; this is dependant on the trigger sensitivity set. If no trigger is detected during this period then the respirator will begin another cycle. In the event of apnoea, the Hayek RTX will deliver the set backup rate.
- Trigger % should be 80-85% if higher you may need to adjust sensitivity, this is to ensure false triggers are prevented.
- Minimum backup rate is 6 per minute i.e. 1 every 10 seconds
- Maximum backup rate is 60 per minute i.e.1 per second
- This mode is fully synchronised with the patient’s own respiration, automatically adjusting the rate and shape of breathing in sympathy with the natural breathing adjustments being made by the patient themselves.
- The patient’ s inspiratory effort creates an initial trigger which is followed by a further trigger by the initial effort of expiration. The trigger can be either through the cuirass or airway.
- Difference between this mode at respiratory triggered is that on this mode the support is timed with patient’s own respiratory pattern, so no I:E ratio is set by the physician.
- The I:E ratio will be calculated and displayed.
- This mode will allow the patient to breathe both at their own rate and determine their own shape.
- In the event of apnoea, the Hayek RTX will deliver the set back up rate delivering fully controlled ventilation at the pressures set