The clinical impact of diaphragm injury
Why current ventilator diagnostics are not enough
Ventilator curves are used to interpret patient respiratory needs, but their primary function is to show what you deliver to the patient. This makes it difficult to detect asynchrony, over-sedation, over-assist and under-assist during spontaneous breathing.
For example, only 21% of clinicians detect asynchrony in the form of missed inspiratory efforts.5 Moreover, a patient on pressure support ventilation can appear to be triggering spontaneous breaths, when in reality they are not triggering any spontaneous breaths at all.5,6
The result is uncertainty about how much breathing effort your patient is exerting and to what extent he or she is at risk of diaphragm injury.
How to monitor the diaphragm
How diaphragm monitoring may help protect the patient and simplify weaning
How diaphragm monitoring may help decrease time on the ventilator
How diaphragm monitoring can help you make more informed treatment decisions
Monitoring diaphragm activity can help you make more informed decisions for your patient throughout treatment and provide valuable information at a number of decision points.
Monitor and trend work of breathing
Identifying over-assist and under-assist
To keep the patient from diaphragm injury, the diaphragm needs to be active at an appropriate level. This is difficult to see without diaphragm monitoring.
For example, a patient can appear to be spontaneously breathing with pressure support but not, in fact, be using their diaphragm at all, as indicated in the image above. This is one example of how over-assistance prevents the diaphragm from working, resulting in diaphragm atrophy. The pressure, flow and volume curves look normal, but the purple Edi signal at the bottom is flat, indicating an inactive diaphragm.
Another example is under-assist, which is the opposite of over-assist and equally bad for the patient. An under-assisted patient uses too much effort to breathe, resulting in diaphragm thickening. This is perhaps easier to observe in the patient, but without an objective value on the ventilator it is difficult to know for sure.
Both examples of diaphragm injury (atrophy and thickening) are frequently seen in patients and associated with worsened clinical outcomes.1
Identifying patient-ventilator asynchrony
Asynchrony is associated with poorer clinical outcomes during mechanical ventilation.18 In a recent study only 21% of clinicians managed to detect asynchrony in the form of missed inspiratory efforts.5 There are many more types of asynchronies that are easily overlooked: ineffective or excessive efforts, delayed inspiratory effort, delayed cycling off, double triggering and auto-triggering.
The image shows how the electrical activity of the diaphragm in grey overlays the pressure curve (yellow), making it easy to see differences in what the patient requests and what the ventilator delivers.
Determine mode of ventilation
Your target should be for the patient to sustain an optimal respiratory effort that represents neither too little nor too much effort.1 By continuously monitoring diaphragm activity, you have an indication of how much the patient is working, if at all. If the diaphragm activity is high and rising, you may have to increase the level of support.19,20,21
If the activity is low or reducing, you may be able to decrease the level of support.19 It is important to also monitor other diagnostic parameters associated with ventilation before changing the support. Research is growing in this area. In the future, more knowledge about diaphragm parameters may improve assessment further.22
Set an optimal PEEP
There is no standardized way of setting the patient's PEEP during spontaneous breathing. Yet a well set PEEP can decrease atelectasis, cyclical opening and closing of airways and protect alveoli. This, in turn, optimizes lung mechanics and improves oxygenation.
PEEP titration with diaphragm monitoring has shown clear results in neonates, allowing the baby to relax appropriately between breaths and preventing derecruitment of the lungs.12
In adult patients, Passath used diaphragm and oxygen monitoring during PEEP changes to allow for identification of a PEEP level at which tidal breathing occurs at minimal effort.23 Excessive lowering of PEEP resulted in an increase in work of breathing by 50 to 60% which, in combination with worsening of oxygen, also suggested partial lung derecruitment.
Optimizing management of sedation
The main benefit of monitoring diaphragm activity in relationship to sedation is to try and keep the diaphragm active as much as possible.1 Simply monitor your patient’s diaphragm activity and response to ventilation to find an adequate sedation level with sustained diaphragm activity.
It may require some training to differentiate the effect of the sedation from other physiology that may impact diaphragm function, however, Edi is particularly effective during sedation holds as you can continuously see the changing effort made by the patient.
Trend and monitor the impact of interventions, rest and rehabilitation
Monitoring diaphragm activity provides further reassurance that the patient can cope with the changes you make. Diaphragm activity is impacted by a range of physiological changes such as rest, sitting up, walking, caffeine treatment and even global rehabilitation and recovery.
If the patient is coping with these changes, diaphragm activity may remain largely unchanged. A worsening of the clinical situation and a requirement for greater respiratory work will most likely increase the diaphragm activity. An improved resting position will lower diaphragm activity needed to generate breaths.
The image shows the continuous diaphragm activity of a patient who was about to be intubated due to acute respiratory distress following pneumonia. By monitoring diaphragm activity, the clinician managed to optimize the support and turn the situation around.
Monitor and trend weaning
As shown in the image, diaphragm dysfunction is strongly linked to weaning difficulties.4 Monitoring diaphragm activity can help you predict weaning readiness and monitor its progress.24-26 All the way from invasive ventilation to non-invasive ventilation, high-flow therapy and when all support has been removed.
The ability of your patient to cope with reduced support is trended within minutes and can help you push-on or fine-tune the support. It may be necessary to go back to your previous settings to prevent your patient from relapsing and the complications which often ensue.
Get started with diaphragm monitoring
Whether you are interested in trying to limit diaphragm injury, reduce sedation and over-assist, or get better insight on patient-ventilator weaning, diaphragm monitoring can help you move forward.
- Goligher EC, Dres M, Fan E, Rubenfeld GD, Scales DC, Herridge MS, Vorona S, Sklar MC, Rittayamai N, Lanys A, Murray A, Brace D, Urrea C, Reid WD, Tomlinson G, Slutsky AS, Kavanagh BP, Brochard LJ, Ferguson ND. Mechanical Ventilation-induced Diaphragm Atrophy Strongly Impacts Clinical Outcomes. Am J Respir Crit Care Med. 2018 Jan 15;197(2):204-213.
- Dres M, Dubé BP, Mayaux J, Delemazure J, Reuter, Brochard L, Similowski T, Demoule A. Coexistence and Impact of Limb Muscle and Diaphragm Weakness at Time of Liberation from Mechanical Ventilation in Medical Intensive Care Unit Patients. Am J Respir Crit Care Med. 2017 Jan 1;195(1):57-66.
- Dres M, Goligher EC, Heunks LMA, Brochard LJ. Critical illness-associated diaphragm weakness. Intensive Care Med. 2017 Oct;43(10):1441-1452.
- Kim WY1, Suh HJ, Hong SB, Koh Y, Lim CM. Diaphragm dysfunction assessed by ultrasonography: influence on weaning from mechanical ventilation. Crit Care Med. 2011 Dec;39(12):2627-30.
- Colombo D, et al. Efficacy of ventilator waveforms observation in detecting patient– ventilator asynchrony. Crit Care Med. 2011 Nov;39(11):2452-7.
- Goligher, E. Diaphragm dysfunction: monitoring and mitigation during mechanical ventilation. Lecture recording, at 23:50: http://www.criticalcarenews.com/webinars-symposia/diaphragm-weakness-clinical-outcomes-mechanical-ventilation/
- Goligher EC, Schepens T. Using ultrasound to prevent diaphragm dysfunction. ICU Management & Practice, Volume 18 - Issue 4, 2018.
- Emeriaud G, Larouche A, Ducharme-Crevier L, Massicotte E, Fléchelles O, Pellerin-Leblanc AA, orneau S, Beck J, Jouvet P. Evolution of inspiratory diaphragm activity in children over the course of the PICU stay. Intensive Care Med. 2014 Nov;40(11):1718-26.
- Bellani G, Pesenti A. Assessing effort and work of breathing. Curr Opin Crit Care. 2014 Jun;20(3):352-8.
- Bellani G, et al. Clinical assessment of autopositive end-expiratory pressure by diaphragmatic electrical activity during pressure support and neurally adjusted ventilatory assist. Anesthesiology. 2014 Sep;121(3):563-71.
- Doorduin J, et al. Automated patient-ventilator interaction analysis during neurally adjusted noninvasive ventilation and pressure support ventilation in chronic obstructive pulmonary disease. Crit Care. 2014 Oct 13;18(5):550. 27.
- Ducharme-Crevier L, et al. Neurally adjusted ventilatory assist (NAVA) allows patient-ventilator synchrony during pediatric noninvasive ventilation: a crossover physiological study. Crit Care. 2015 Feb 17;19:44.
- Doorduin J, et al. Automated patient-ventilator interaction analysis during neurally adjusted noninvasive ventilation and pressure support ventilation in chronic obstructive pulmonary disease. Crit Care. 2014 Oct 13;18(5):550.
- A Skorko, D Hadfi eld, A Vercueil, C Bell, A Feehan, K Peters, P Hopkins. Retrospective review of utilisation and outcomes of diaphragmatic EMG monitoring and neurally adjusted ventilatory assist in a central London teaching hospital over a 3-year period. Critical Care 2013, 17(Suppl 2):P146.
- Rahmani A, Ur Rehman N, Chedid F. Neurally adjusted ventilatory assist (NAVA) mode as an adjunct diagnostic tool in congenital central hypoventilation syndrome. J Coll Physicians Surg Pak. 2013 Feb;23(2):154-6.
- Stein H, Firestone K. Application of neurally adjusted ventilatory assist in neonates. Semin Fetal Neonatal. Semin Fetal Neonatal Med. 2014 Feb;19(1):60-9.
- Bellani G, Mauri T, Coppadoro A, Grasselli G, Patroniti N, Spadaro S, et al. Estimation of patient’s inspiratory effort from the electrical activity of the diaphragm. Crit Care Med 2013;41:1483e91.
- Thille AW, Rodriguez P, Cabello B, Lellouche F, Brochard L. Patient-ventilator asynchrony during assisted mechanical ventilation. Intensive Care Med. 2006 Oct;32(10):1515-22.
- D. Colombo, G. Cammarota,V. Bergamaschi, M.De Lucia, F.D. Corte, and P. Navalesi, “Physiologic response to varying levels of pressure support and neurally adjusted ventilatory assist in patients with acute respiratory failure,” Intensive CareMedicine, vol. 34, no. 11, pp. 2010–2018, 2008.
- Bellani G1, Mauri T, Coppadoro A, Grasselli G, Patroniti N, Spadaro S, Sala V, Foti G, Pesenti A. Estimation of patient's inspiratory effort from the electrical activity of the diaphragm.. Crit Care Med. 2013 Jun;41(6):1483-91.
- Liu L, Liu H, Yang Y, et al. Neuroventilatory efficiency and extubation readiness in critically ill patients. Crit Care 2012; 16:R143.
- Jansen D, Jonkman AH, Roesthuis L, et al. Estimation of the diaphragm neuromuscular efficiency index in mechanically ventilated critically ill patients. Crit Care. 2018 Sep 27;22(1):238.
- Passath C, Takala J, Tuchscherer D, Jakob SM, Sinderby C, Brander L. Physiologic response to changing positive end-expiratory pressure during neurally adjusted ventilatory assist in sedated, critically ill adults. Chest. 2010 Sep;138(3):578-87.
- Barwing J, Pedroni C, Olgemöller U, Quintel M, Moerer O. Electrical activity of the diaphragm (EAdi) as a monitoring parameter in difficult weaning from respirator: a pilot study. Crit Care. 2013 Aug 28;17(4):R182. doi: 10.1186/cc12865.
- L. Liu, H. Liu, Y. Yang, Y. Huang, S. Liu, J. Beck, et al. Neuroventilatory efficiency and extubation readiness in critically ill patients. Crit Care, 16 (2012), pp. R143.
- H. Rozé, B. Repusseau, V. Perrier, A. Germain, R. Séramondi, A. Dewitte, et al. Neuro-ventilatory efficiency during weaning from mechanical ventilation using neurally adjusted ventilatory assist. Br J Anaesth, 111 (2013), pp. 955-960.