In this podcast, we talk about the clinical journey of a COVID-19 patient and some insights from the critical care unit. There are some concepts here that we probably don’t do full justice to in the time we had, so here are some accompanying notes and links to help those of you who want to deep dive into certain areas
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Getting the COVID-19 basics right
A thorough history and evaluation for everyone with suspected or confirmed COVID-19 coming through the doors into ED is absolutely essential. Don’t miss dual pathology. Think hard about whether they need a CT or a CTPA to evaluate the lungs further and use the national decision support tools. Evaluate work of breathing and think about physiology1 – don’t make decisions about referral/escalation based purely on numbers. Consider early arterial lines for those previously fit patients that look like they are heading towards ICU. And consider early Clinical Frailty Scoring and sensible discussions2 for those patients who look sick, but you have doubts about whether intensive care is really appropriate.
What happens then?
For patients with evidence of respiratory failure who are less sick, CPAP is now encouraged by NHSE to reduce work of breathing and increase lung recruitment3. This is considered to be an aerosol generating procedure currently, although there is ongoing discussion on that4. Local factors and individual patient trajectory will determine where and when this can happen. Intensive Care Society (ICS) knowledge sharing information and statements on CPAP may be helpful5. Alternatively, you could get involved and recruit to the Recovery RS trial. This is great – takes the complex decisions out of your hands and contributes to the evidence base to boot.
In the really sick patients, MERIT teams are encouraged6 and can scoop people up from the ED in order to deliver airway management and expertise in a dedicated and prestocked ‘intervention room’, somewhere within or adjacent to the ICU. There are huge benefits to this: an overall reduction in PPE use; psychological safety of a prepared and familiar environment; limited personnel exposure to AGPs and sequential interventions delivered by expert teams doing these things regularly in PPE. But, of course, this will depend on local engagement and whether patients are clinically safe to be transferred out of the Emergency Department.
What about the sicker COVID-19 patients? What interventions other than CPAP can we consider immediately?
I always struggle to identify the benefits of prone positioning off the cuff, but we tried in the podcast! The rationale is explained better in this comprehensive review7, by real experts in the field. Here is one of the key papers to support prone positioning for severe ARDS8. The ICS have produced some UK guidance on when you might think about doing this9, and a proposed P/F ratio (see below) to help guide proning teams.
Prone positioning in awake patients has a negligible evidence base. I have only ever seen a few case series10 which report transient improvement in oxygenation. Having said that, if patients will tolerate it then the risks seem low. The ICS has produced a document to support trials of awake prone positioning11. Perhaps worth a try? Don’t expect miracles though.
What are the challenges with invasive ventilation in COVID-19 patients?
Initial safety around RSI in these patients should focus on ensuring adequate preload, a stable cardiovascular drug induction and maximising the chances of first pass success. The RCOA/ICS/FICM repository is an excellent resource that goes into great depth here.
Bronchoscopy is useful for sputum clearance and to assess tube patency. We are changing a lot of tubes after short periods and secretions are tenacious and challenging to manage. Have you got an ambuscope or other way of doing this in ED if your ICU is backed up? If not, you could think about it.
Inhaled nitric oxide therapy is being muted again as a pulmonary vasodilating agent to help reduce shunt. Limited evidence in support of its use in prior ARDS studies12, but these are new times and with new times everyone likes to get the old machines back out. HFOV (High Frequency Oscillation Ventilation) anyone13….?
Here are some nice cheat sheet resources for inspiratory and expiratory holds14 which we discuss briefly in the podcast.
What’s a P/F ratio and what’s all this about shunt and dead space? Some physiology revision…
The Horowitz index (P/F ratio)15 tries to provide a reliable estimate of the trade-off between inspired oxygen and the oxygen pressure in the blood. It is popular, so much so that it has made it into the official Berlin definition of ARDS and it has formed part of the entry criteria for multiple clinical trials in this area. Make sure you know your mmHg from your kPa if you are using it, how to convert between the 2 and what the output means.
Shunt refers to perfusion without ventilation.
Dead space refers to ventilation without perfusion.
In truth, it is a bit more complicated than that and the two often interlink, but the above describe good back to basics principles. Unfortunately in COVID-19, there is often a problem with both….
What’s autoPEEP again?
This was an interesting sideline, but it should be noted that we aren’t seeing a huge amount of gas trapping and autoPEEP in COVID-19. Read more about it here 16.
You mentioned specific problems with HME condensation/clotting in COVID-19. What’s all this about?
A standard HME offers some degree of heat and moisture exchange while also filtering out bacterial and viral pathogens. Unfortunately, these filters appear to be clogging with secretions and condensation more than ever in COVID-19, which limits delivery of gas flow. This has been such an issue that the Faculty of Intensive Care Medicine (FICM) have issued a safety update on it17. Be wary of this and consider introducing a HME check/change as part of your daily rounds on these patients.
What about outcomes – what is happening to these patients?
ICNARC will continue to produce data on this18 and you should keep an eye out for it. The latest report has figures on >5500 patients. There are also opinion pieces on different phenotypes of COVID-19 lung19.
And what’s it really been like on the ICU?
In a word, tough. Looking after sick colleagues is really difficult21. There are some psychological support and wellbeing resources22 and we would encourage anyone who has encountered this to talk about it with friends, mentors and psychology colleagues. PPE is an ongoing debate, but even when you have enough and you get it on, the challenges of staying in it for long periods of time are real.
Also, the pace and scale of change has been mentally exhausting. However, there have been lots of fantastic examples of broken silo’s, teamworking and kindness. We have also been lucky enough to receive exemplary support from relevant health professionals and digital colleagues. The way we are delivering research during this time has also been fairly revolutionary, and a thing to behold.
I hear that about once a day at the moment. Well done Dickens. Still relevant.
Stay safe everyone.
- 1.Tobin MJ. Basing Respiratory Management of Coronavirus on Physiological Principles. Am J Respir Crit Care Med. April 2020. doi:10.1164/rccm.202004-1076ed
- 2.COVID-19 Rapid Guideline: Critical Care in Adults. National Institue for Clinical Excellence; 2020:1-13. https://www.nice.org.uk/guidance/ng159. Accessed April 21, 2020.
- 3.Guidance for the Role and Use of Non-Invasive Respiratory Support in Adult Patients with COVID19 (Confirmed or Suspected), Version 3. NHS England and NHS Improvement; 2020:1-11.
- 4.Iwashyna TJ, Boehman A, Capelcelatro J, et al. Variation in Aerosol Production Across Oxygen Delivery Devices in Spontaneously Breathing Human Subjects. April 2020. doi:10.1101/2020.04.15.20066688
- 5.Eddleston J, Pittard A. Use of Continuous Positive Airway Pressure (CPAP) for COVID-19 Positive Patients. Letter produced by the Faculty and the NHSE Adult Critical Care Clinical Reference Group and endorsed by the Intensive Care Society; 2020:1. https://www.ficm.ac.uk/news-events-education/news/letter-regarding-use-continuous-positive-airway-pressure-cpap-covid-19. Accessed April 21, 2020.
- 6.Clinical Guide for the Management of Critical Care Patients during the Coronavirus Pandemic. NHS; 2020:1-7.
- 7.Gattinoni L, Taccone P, Carlesso E, Marini JJ. Prone Position in Acute Respiratory Distress Syndrome. Rationale, Indications, and Limits. Am J Respir Crit Care Med. December 2013:1286-1293. doi:10.1164/rccm.201308-1532ci
- 8.Guérin C, Reignier J, Richard J-C, et al. Prone Positioning in Severe Acute Respiratory Distress Syndrome. N Engl J Med. June 2013:2159-2168. doi:10.1056/nejmoa1214103
- 9.Vercueil A, Patel B, Martin D. COVID-19: A Synthesis of Clinical Experience in UK Intensive Care Settings. The Intensive Care Society ; 2020:1-2. https://renal.org/wp-content/uploads/2020/04/COVID-19_synthesis-of-clinical-experience-in-UK-intensive-care_04.04.2020_FINAL.pdf. Accessed April 21, 2020.
- 10.Scaravilli V, Grasselli G, Castagna L, et al. Prone positioning improves oxygenation in spontaneously breathing nonintubated patients with hypoxemic acute respiratory failure: A retrospective study. Journal of Critical Care. December 2015:1390-1394. doi:10.1016/j.jcrc.2015.07.008
- 11.Bamford P, Bentley A, Dean J, Whitmore D, Wilson-Baig N. ICS Guidance for Prone Positioning of the Conscious COVID Patient 2020. The Intensive Care Society; 2020:1-6. https://emcrit.org/wp-content/uploads/2020/04/2020-04-12-Guidance-for-conscious-proning.pdf. Accessed April 21, 2020.
- 12.Gebistorf F, Karam O, Wetterslev J, Afshari A. Inhaled nitric oxide for acute respiratory distress syndrome (ARDS) in children and adults. Cochrane Database of Systematic Reviews. June 2016. doi:10.1002/14651858.cd002787.pub3
- 13.Sud S, Sud M, Friedrich JO, et al. High-frequency oscillatory ventilation versus conventional ventilation for acute respiratory distress syndrome. Cochrane Database of Systematic Reviews. April 2016. doi:10.1002/14651858.cd004085.pub4
- 14.Yartzev A. Alveolar pressure and the inspiratory hold manoeuvre. deranged physiology. https://derangedphysiology.com/main/cicm-primary-exam/required-reading/respiratory-system/Chapter%205591/alveolar-pressure-and-inspiratory-hold-manoeuvre. Accessed April 21, 2020.
- 15.Horowitz Index for Lung Function (P/F Ratio). MD Calc. https://www.mdcalc.com/horowitz-index-lung-function-p-f-ratio#use-cases. Accessed April 21, 2020.
- 16.Intrinsic POOP. https://litfl.com/intrinsic-peep/. https://litfl.com/intrinsic-peep/. Accessed April 21, 2020.
- 17.COVID-19: Very Rapid Updates and Safety (ViRUS). Faculty of Intensive Care Medicine; 2020:1. https://www.ficm.ac.uk/sites/default/files/virus1_0.pdf. Accessed April 21, 2020.
- 18.ICNARC Report on COVID-19 in Critical Care. Intensive Care Natioinal Audit and Research Centre; 2020:1-24. https://www.icnarc.org/Our-Audit/Audits/Cmp/Reports. Accessed April 21, 2020.
- 19.Gattinoni L, Chiumello D, Caironi P, et al. COVID-19 pneumonia: different respiratory treatments for different phenotypes? Intensive Care Med. April 2020. doi:10.1007/s00134-020-06033-2
- 20.Griffiths MJD, McAuley DF, Perkins GD, et al. Guidelines on the management of acute respiratory distress syndrome. BMJ Open Resp Res. May 2019:e000420. doi:10.1136/bmjresp-2019-000420
- 21.Svantesson M, Carlsson E, Prenkert M, Anderzén-Carlsson A. ‘Just so you know, the patient is staff’: healthcare professionals’ perceptions of caring for healthcare professional–patients. BMJ Open. January 2016:e008507. doi:10.1136/bmjopen-2015-008507
- 22.Free access to mental wellbeing platform for medical and emergency workers during Covid-19. Royal College of Emergency Medicine. https://www.rcem.ac.uk/RCEM/News/News_2020/Free_access_to_mental_wellbeing_platform_for_medical_and_emergency_workers_during_Covid-19.aspx. Published April 3, 2020. Accessed April 21, 2020.
- 23.Dickens C. A Tale of Two Cities. Penguin Classics; 1859.