Notes on BIPAP/CPAP. M.Berry Emergency physician St Vincent s Hospital, Sydney

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Cody Bell
5 years ago
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1 Notes on BIPAP/CPAP M.Berry Emergency physician St Vincent s Hospital, Sydney

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3 DEFINITIONS Non-Invasive Positive Pressure Ventilation (NIPPV) Encompasses both CPAP and BiPAP Offers ventilation support to spontaneously breathing patients IPAP Inspiratory positive airway pressure EPAP Expiratory positive airway pressure Continuous Positive Airway Pressure (CPAP) Pressure is delivered at the same level throughout the respiratory cycle, ie, pressure delivered during inspiration is the same as pressure delivered during expiration IPAP and EPAP are the same BiPAP A higher pressure is delivered during inspiration than during expiration IPAP is greater than EPAP 3

4 EFFECTS CPAP The pressure has the effect of holding the alveoli open larger like a balloon with more air in it is bigger a bigger balloon means a greater surface area for gas exchange and hence better oxygenation The pressure prevents some alveoli from closing during expiration so the surface area is available during expiration as well as inspiration and hence better oxygenation Alveoli that are already open for the next inspiration means less work of breathing to open then up. Alveoli being held open, rather than collapsing with each breath, is thought to be less traumatic for damaged lung such as in ARDS BiPAP Has the benefits of CPAP plus inspiratory support Has the effect of increasing the volume of each breath, ie, a greater tidal volume Less work to achieve a normal size breath More ventilation (ie more air moving in and out of the patient) means more breathing off of CO2 4

5 Indications for NIPPV Acute respiratory failure o CAL o APO o Asthma Patient needs to be o Awake o Cooperative o Able to initiate each breath o Not have excessive airway secretions Contraindications to NIPPV Cardiac/respiratory arrest Inability to protect airway Copious secretions/bleeding/vomiting Significant hypotension Airway obstruction Uncooperative patient/ not tolerated Intubation indicated Facial/ BOS fractures Untreated pneumothorax Complications of NIPPV Hypotension Barotrauma Pressure sores Conjunctivitis Gastric reflux Aspiration (rare) Dry mucous membranes and thick secretions 5

6 Starting NIPPV Explanation to patient key to compliance Decide on communication strategy o Difficult for the patient to talk while on CPAP/BiPAP o Can be distressed that they can t communicate problems Good patient position improves ventilation Start with low pressures (eg 8/4-10/5) to make it easier for patient to tolerate, this can then be weaned up according to patient response The mask can be held onto the patient s face initially before applying the straps so that the patient doesn t feel strapped in without escape! Can start with high FiO2, but this should be weaned down as soon as possible Strategies during therapy Patient may develop hypotension due to increased intrathoracic pressure particularly if hypovolaemic. Monitor blood pressure and use IV fluid boluses as appropriate. Titrate pressure settings to patient response and needs o Tidal volumes Aim for 5-8mL/kg If too low, increase IPAP relative to EPAP If too high, decrease IPAP relative to EPAP o Oxygenation Improved by an increase in background pressure ie, CPAP/EPAP 6

7 Increase CPAP or EPAP up to 10 as needed (if more than required, consider need for intubation) IPAP will need to be increased by the same amount to maintain the same pressure difference between inspiration and expiration Wean FiO2 as soon as possible o Hyper oxygenation has complications o Oxygen Sats >90% or po2 >70 is sufficient o Oxygen is absorbed and to 100% oxygen can cause resorption atelectasis where as nitrogen is not resorbed so can help splint the alveoli open Review patient frequently o Can deteriorate and subsequently need intubation o Adjusting the ventilator settings according to the patient s response and needs allows for maximum benefit. Nebulisers can be administered through the circuit. Taking the patient on and off NIPPV allows alveoli to collapse that were being held open better to wean the patient than give them breaks 7

VENTILATORS PURPOSE OBJECTIVES

VENTILATORS PURPOSE OBJECTIVES VENTILATORS PURPOSE To familiarize and acquaint the transfer Paramedic with the skills and knowledge necessary to adequately maintain a ventilator in the interfacility transfer environment. COGNITIVE OBJECTIVES