Alternatives to IPPB: a tutorial By Elizabeth Kelley Buzbee AAS, RRT-NPS, RCP

IPPB As we know, IPPB is the application of an IC [inspiratory capacity] via application of positive pressure sent into the lung with an inline SVN, so that both IC and drugs are delivered to the lung of a person who cannot take a deep enough breath spontaneously to distribute alveolar ventilation and medication to the periphery of the lung

Problems with IPPB The machines are fairly complex, break down easily and the patient has to learn some fairly complex skills to optimize his therapy. The hazards of IPPB are associated with the hazards of any form of positive pressure: barotrauma and interference with the cardiovascular system being the worst

Alternatives to IPPB Over the last few years, as IPPB has wained in popularity other forms of hyper – inflation have evolved. Obviously, IS is one of these forms of hyperinflation, but we will discuss a few, more invasive forms of hyperinflation today

PAP PAP: Positive Airway Pressure: advantage is that it easier to do than IPPB; some methods don’t even require a 02 source. Application of Positive Airway pressure can take several forms: –CPAP –EPAP –PEP –ezPAP –Retard valve [not really an alternative, but added to the IPPB] We will discuss each of these 4 methods

CPAP

constant positive airway pressure breathing. The pressure base line is raised from zero to a positive number. The CPAP has only one parameter and that is the baseline pressure. CPAP 5 means the baseline has risen to 5 cmH20. The patient breathes spontaneously on this higher baseline pressure. For example: you normally breathe between -5 to zero. On IPPB you may alternate between -2 and +15, but with CPAP 5, you are breathing +3 to + 5.

CPAP While there are a variety of methods that CPAP can be created, essentially in CPAP breathing, the patient is not allowed to exhale completely so that as he breathes, his airways are subjected to a positive pressure throughout both inspiration and exhalation. This is done, by creating an obstruction at the exhalation port so that the exhalation valve fails to open completely for the entire time. The actually pressure changes in CPAP are minor only--- only about 2- 4 cmH20.

REFER: This pressure time curve shows a CPAP 10. Note, how as the patient breathes, the pressure only varies a bit between inspiration and exhalation

Effects of CPAP Most likely, this CPAP action results in backpressure sent along the airways and into the periphery of the lung. Atelectatic alveoli will open [be recruited] and the FRC should return to normal with the lung compliance returning to normal. Alveoli are connected together with collateral channels such as Pores of Kahn so that gas moves from one set of alveoli to another.

CPAP can be applied in one of two ways. Continuous CPAP Intermittent CPAP

Continuous CPAP –The most common method is to place a patient on a mechanical ventilator and rise the baseline pressure for continuous application of CPAP. –This method has replaced the Briggs adaptor because more than a couple of hours breathing on a Briggs adaptor [t-tube] will cause atelectasis in the lung periphery due to increased Raw of the endotracheal tube. –Patients who come off mechanical ventilation used to go on the t-tube for a few hours before extubation— now we keep them on CPAP –CPAP for long periods of time is generally limited to low levels of pressure because high levels of CPAP can cause hypercapnia as the Vt drops

Intermittent CPAP CPAP has been investigated as a short term therapy for recruitment of alveoli. A patient is exposed to a few seconds of a high level of CPAP. Follow up X-rays have shown increased alveolar ventilation and a rise in Pa02 at least for a short time. The long-term advantages of alveolar recruitment procedures is not clear

Hazards of CPAP The problem with CPAP is that the alveolar recruitment may only last 10 minutes after the Tx is over. CPAP can decrease venous return to the right heart and reduce Cardiac output. Higher levels of CPAP can decrease the Vt and PaC02 rises and the Ph drops to acidic levels

EPAP

 this is the baseline pressure on the BiPap machine. We select EPAP and a pressure, and in the EPAP only mode, it is, for all practical purposes, CPAP.  The advantage of the BiPAP machine is that the patient doesn’t have to be intubated, rather he uses a nose mask for BiPap.  In EPAP 5, the patient will alternate between +3 and +5… just like with CPAP.  This has not been done intermittently, but continually as are most forms of mechanical ventilation --but because the patient uses a mask, this technique could be used for shorter periods of time.

BiPAP machine Nose mask

EPAP hazards Same as CPAP.

EzPap This is a device that creates back pressure within a small hand-held device that the patient breathes through. It is not CPAP because the variations between inspiratory and expiratory pressure are much higher than with CPAP. EzPap uses a gas flow into a specially constructed device to create the higher pressures It can be used with a SVN inline for drug delivery or could be used dry

Go to this page to access ezPAP online video

PEP

 PEP: [page of Egan’s Fundamentals] is used in both secretion clearance and in hyperinflation.  In PEP positive expiratory pressure, there is no 02 flow into the device. Rather the patient exhales through a restricted orifice creating back pressure up the airways. This back pressure should transmit into the alveoli and increase their diameter [and volume] just as CPAP does   library/invoke.cfm?objectid=FF7A803A-969E library/invoke.cfm?objectid=FF7A803A-969E  -4B62-B345FA1BF0A22432&method=display -4B62-B345FA1BF0A22432&method=display

EzPAP

ezPAP  gas flow into a device where a positive pressure on both inspiration and exhalation occurs as the patient breaths spontaneously.  Different from CPAP in that there are bigger changes in the higher pressure and the lower pressure. This machine creates these pressures with the Coanda effect

Note: this ezPAP has a SNV inline between the mouthpiece and the ezPAP. This setup requires a drive line for the creation of pressure [B] and a driveline A for the creation of the mist. The third line C would go to a manometer A B C

Go here to find a sample patient evaluation form for use with the ezPAP. This document includes indications, contraindications and assessment tools valuation_Form.pdfhttp:// valuation_Form.pdf

Go to this website to access a video on PEP

Retard valve The retard valve is used with IPPB, so it doesn’t replace the IPPB.

retard valve:  additional pressure is placed on the exhalation valves so that the exhalation is slower—this mimics purse-lipped breathing. This valve retards exhalation and creates backpressure to keep the airways open.  Retard valves should never be put on IPPB exhalation valves without a specific order as they have been associated with pneumothorax  Expiratory retard is indicated in cases of airtrapping to mimic purse-lipped breathing

The expiratory retard valve on the Bennett IPPB circuit replaced the usual exhalation valve. It used a spring against the exhalation port that could be tightened to keep gas in the circuit, thus slowing down exhalation through the exhalation valve by decreasing it’s diameter. The Bird uses a cap that fit over the exhalation port that could be dialed from a larger port to a smaller one to increase or decrease exhaled flow rate These devices both caused restriction to exhaled flow. [reference: Sills]

Problems with expiratory retard If the retard makes exhalation too slow, higher pressure built up in the thoracic cavity, decreases CO and exhalation is too slow. If the retard makes exhalation too fast, there wasn’t enough retard to open the airway. Ask the patient how they feel about the results of the retard valve. They can feel the difference in their exhalation [refer: sills]

Reference page Egan’s page: ezPAP web pages PEP device web pages McPherson’s Respiratory Care Equipment Sill’s “Respiratory care Registry guide”