We use Assit Control for lung transplants and PRVC for all other transplants.

Hi Brooke, I assume you mean "Volume Assits/Control"? What is your reasoning for differentiating the modes between lung transplants and other transplants?

That is indeed what I meant. I have to be honest and tell you that we only use volume assits/control because the MD director of the lung transplant program was not fond of using PRVC. I am unsure of his reasoning behind this as I am no longer working in the unit. I do work with him in another area though, and would be happy to ask him and relay his thoughts if you would like.

Not sure that mode is the issue so much as tidal volume limitation. It is increasingly apparent that even in the absence of lung injury that tidal volumes in excess of 8 cc/kg ideal body weight are associated with adverse outcomes and creation of clinically apparent lung injury (Futier E, et al. 2013; Serpa Neto, A, et al. 2012). Thus, not sure it matters what control variable is used (pressure or volume or both), but in the absence of spontaneous breathing controlled mechanical ventilation (AC - but not really assisted without spontaneous breaths) would be most commonly used (volume control AC, pressure control AC, pressure regulated volume control AC). Given that higher tidal volumes increase the generation within the lung of potentially injurious mediators that are systemically active and can lead to organ failures, it seems prudent that tidal volume limitation is appropriate for all organ donors, not just lung. There is one prospective randomized controlled trial (Mascia L, et al 2010) that indicates that tidal volume limitation will increase the number of eligible and harvested lungs from potential donors.

we use PRVC for heart transplant donors

In our ICU we mostly use Pressure Control Ventilation associated to a "protective lung strategy" (Vt= 6ml/k and adjusted PEEP in order to keep the lung open) avoiding alveolar collapse. I can´t see any further advantage with APRV

In our ICU we mostly use Pressure Control Ventilation associated to a "protective lung strategy" (Vt= 6ml/k and adjusted PEEP in order to keep the lung open) avoiding alveolar collapse. I can´t see any further advantage with APRV

Conventional modes of mechanical ventilation (i.e. PCV) are usually good enough to achieve the targets of:

FiO2 titrated to keep oxygen saturation >=95% and/or PaO2 >= 80mmHg; pH 7.35-7.45, PaCO2 35-45 mmHg and PEEP usually is maintained at 5 cmH2O, although increases up to 15 and recruitment maneuvers may be used.

volume a/c mode (control), adjust volume and peep base on lung pathology, and donor organization guidelines which is 10-12ml/kg of ibw. Seems that the protocol is more incline to open the lung"avoid atelectasis". Surgeon approach. Use of pcv In case of small e/tt and co-existence of pulmonary diseases and increase in resistance of airway. Experience in prior institution.

The volume modes differ only in their response to patient triggering are selected : Once patient is brain dead there will be no "patient interaction and therefore difference between all of the volume modes(v-AC, SIMV VC, CMV) , as the patient will not be actively interacting with the ventilator-. Synchrony is assured and inspiratory triggering can be turned off. javascript:

Standard pressure modes ( PCV, SIMV-PC) will also be identical. The volume targeted pressure control modes such as PRVC, will have less interference and dys-synchrony, so should work well.

The aim , as stated above, should be to have low tidal volume (less than 6ml/kg IBW) and pressure limited ventilation (Plateau pressure

We use APRV for all donors.

We routinely use APRV for donors.

We use Protective Strategy (Driving Pressure

Accordingto the data published by Mascia (JAMA, 2010, 304, 2620),we use volume control ventilation with VT 6 to 8 mL/Kg, PEEP 8 to 10 cm H2O (according to the hemodynamic tolerance and respiratory mecanics (we use the stress index). We use CCS for trachal aspiration and performed the apnea test in CPAP. RM were performed after each disconnection.

Thanks for the reference Thierry. The Mascia study concluded that "use of lung protective strategy (tidal volume 6-8 mL/kg and PEEP 8-10 cm H2O) increased the number of eligible and harvested lungs compared to conventional ventilation (tidal volume10 -12 mL/kg and PEEP 3-5 cm H2O). The study did not describe whether pressure control of volume control modes were used.

Assuming the same tidal volume, volume control (without an inspiratory hold) is expected to differ from pressure control in that the mean airway pressure will be higher for PC and the lungs will open earlier in the inspiratory time. These effects may improve oxygenation but I am not aware of any research like this in a donor population. This seems to be the motivation for people who use APRV.

Use of adaptive targeting for pressure control (aka volume targeted pressure control) would not seem to be necessary as donor lung mechancis should not change much over time (but I have no experience here so any comments would be welcome).

Louis, you mentioned "donor organization guidelines which is 10-12ml/kg of ibw", can you give us a reference?

Ippv

In our ICU we normally use SIMV VC 6-8mL/Kg, 5-10cmH2O PEEP, again depending on lung pathology / ABG and raise the insp sesitivity to decrease autocycling due to Aortic pulsations. We do not use PCV unless trhe Tx surgeons request it. (cut from protcol below)

Ventilate to normocarbia

Vt 6-8 ml/kg

Lowest FiO2 to maintain PaO2 > 80mmHg, SaO2 > 95%

PEEP 5 -10cmH2O

Peak inspiratory pressures

Good suggestion from Ian Rogers concerning inspiratory trigger sensibility. In brain-dead patients, there is an hyperdynamic cardiovascular status.Cardiogenic ventilator autotriggering may be misinterpreted during the apnea test, delaying the diagnosis of brain death. It's important to check the sensitivity of the inpiratory trigger.

Arbour RB, Int and Crit Care Nursing, 2012, 28, 321

Arbour RB, Am J Crit Care, 2009, 18: 496, 488

We have recently completed a systematic review examining the use of lung management protocols in potential organ donors and we can let you know when this work has been accepted for publication. I will upload this abstract to my profile shortly as we presented this at the Australian and New Zealand Intensive Care Society/Australian Critical Care College of Nursing Annual Scientific Meeting last year.

There is little detail available about the best method of ventilation for optimising lung health for procurement.

Thanks Elizabeth. Do you get the impression that this would be a fruitful area of research?

Good question, I am not aware of any studies specifically looking into this population and the effect that ventilation-induced inflammation may have in the viability of organs for donation. Since there is no specific literature I would recommend a protective ventilation strategy (VT5-7cmH2O, minimum FiO2 for acceptable oxygenation) suggested by other colleagues ("primum non nocere" approach). It makes sense to think that these patients' lungs are already "primed" for lung inflammation development and the consequences this could have on systemic inflammation and the viability/function of donated organs should be further studied. A cautious vs. conventional ventilatory approach could potentially improve graft function and relief donation pool shortage.

It seems that we all favor a lung protective strategy. I wonder if anyone has tried HFO as a logical extention of the "small tidal volume" ideal. It would be much easier to use with a donor due to the lack of inspiratory efforts. I am aware of the recent negative trials of HFO but donors may be a different population. Any ideas?

JAMA. 2010 Dec 15;304(23):2620-7. doi: 10.1001/jama.2010.1796.

I am working in a tertiary transplant center (all except pancreas/gut Tx), and we use normal protective ventilation i.e. pressure controlled targeting 6-8 ml/kg Tv, PEEP as low as possible but at least 5 cm H2O.

I'm not aware of protocols using APRC in brain dead patients. However, as reported by Daoud (Ann Thorac Med 2007; 2(4): 176–179 - doi: 10.4103/1817-1737.36556): "if the patient has no spontaneous respiratory effort, APRV becomes typical to ‘inverse ratio pressure’-limited, ‘time cycle’-assisted mechanical ventilation (pressure-controlled ventilation). Therefore, to the best of my understanding APRV could be used in BD patients as a lung protective strategy.

Ehab Doud worked with me in my simulation lab to understand APRV. Indeed, APRV is simply pressure control intermittent mandatory ventilation and because the inspiratory time (aka T-high) is so long, the rate of mandtory breaths is usually low, around 10/minute. That means the patient must support the rest of a relatively high mintue ventialtion requirement by spontaneous breaths. Obviously, donors cannot do this, so the lower the frequency of mandatory breaths in APRV, the higher their tidal volume must be, thus defeating the intention of a lung protective strategy. Seems to me the ideal strategy wouild be PC-Continuous Mandatory Ventilation with a preset optimal PEEP (base on lung mechanics) and a high enough frequency to keep the tidal volume as low as possible. Keep the I:E at 1:1 and use a higher frequency to allow a lower tidal volume. With this strategy there is no need to worry abourt autoPEEP (as opposed to APRV that depends on an uncertain level of autoPEEP). Of course you could do this with volume control but in general pressure control is better at recruiting lung units during inspiration (alveolar pressure is higher earlier in the inspiratory time) and is simply easier to implement on most ventialtors (ie, no need to adjust flow to keep a constant I:E when increasing frequency).

This seems to come up a lot in my research. I have only been working at my OPO for a month but I have 2 years of Respiratory Therapy experience. I noticed that throughout my career as an RT, patients who were on PCV experienced less instances of atelectasis and de-recruitment. The appliance of consistent pressure during inspiratory time leads to better recruitment of the alveoli, most effectively in the apices of the lungs. In most Volume Control settings, the physiology from my education and understanding is that the rising pressure to achieve the set volume will follow the path of least resistance.

That is generally true. The effect of better recruitment follows from the fact that for the same tidal volume and inspiratory time, PCV results in a higher mean airway pressure (and hence higher mean lung volume than VCV). To get the same mean airway pressure with VCV you have to raise the PEEP which puts the lung at risk for volutrauma (over distention identified as ventilating on the flat portion of the PV curve). This is one reason people are attracted to APRV for lung donors. However, this is not the optimal  mode for technical reasons (see attached paper). You can achieve mean airway pressure and end expiratory pressure with regular PCV but with elevated frequency (for lower tidal volumes but adequate minute alveolar ventilation).

Hello All,  In my experience with lung donations, I have used both volume targeted adaptive modes as well as Pressure Control.  Both have done well with the use of appropriate PEEP settings.  Utilizing lung recruitment strategies and lung protective strategies have helped me promote better procurement rates for donor lungs as well as maintaining better results for other organs as well.  I agree that there are more effective ways to maintain a higher mean airway as well as end expiratory pressures than APRV.  Thanks Rob for the article. 

Great question, and a topic we need to pay a lot of attention to. We use VC-CMV, with low VT and moderate PEEP levels. Thank you all for the very interesting Q&A

Kevin bring up an interesting idea about the difference between PC and VC in terms of "following the path of least resistance." Attached is a paper that discusses the theory behind this. As with everything in life, it is more complicated than it seems.