Vent Management for COVID-19 Patients

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Dr, Lindsay Ritter, MD- updated 04/12

Key Points

  1. ARDSnet management with low tidal volumes (6-8 cc/kg)
  2. Aim for plateau pressures <30 cm H20
  3. Higher PEEP strategy
  4. Paralysis and prone positioning work extremely well, start early proning
  5. Consider APRV ventilation
  6. Diuresis – keep your patients dry

Literature

Since December, troubling reports of respiratory failure associated with a novel coronavirus has swept the globe. Although the true incidence of hypoxic respiratory failure in patients with COVID-19 is unclear, the prevalence appears to be around 19%1,2. Reports from China appear to show that 2.3% to 12% require intubation and mechanical ventilation due to the severity of their disease1-3. A study out of China on 52 critically ill COVID-19 patients reported that 67% of these patients developed ARDS, while 56% needed mechanical ventilation, and non-survivors were more likely to receive mechanical ventilation3. Away from the epicenter in China, however; a lower percentage of patients seem to have developed ARDS requiring intubation as seen from extracted data of a total of 1,099 patients through the end of January 2020 that showed 16.2% were admitted to the ICU and 8.3% of patients underwent mechanical ventilation4.  Another  retrospective case series of 138 COVID-19 patients in China, it was noted that the time to development of ARDS was 8 days, while 42.7% received mechanical ventilation5.                    

There are currently no studies on mechanical ventilation strategies in COVID-19. Society of Critical Care Medicine recently released several guidelines on the management of these patients which is closely based off the management of ARDS patients.  Their recommendations are based on previous data showing an increased mortality with high tidal volumes versus a reduced risk of death with protocolized low tidal volume strategies2,6,7. Akin to low tidal volume strategies, there are no current research articles regarding targeting plateau pressures <30 cm H20. RCTs and meta-analysis have determined that ventilatory protocols with low plateau pressures decreased short term mortality6. Both strategies ideally help to limit the amount of ventilator induced volutrauma. Ventilation with these lower volumes may result in elevations in pCO2 and a respiratory acidemia, termed permissive hypercapnia. Typically, the current consensus is that it is safe to allow the pH to fall to 7.20.

Extrinsic PEEP has been used to prevent atelectotrauma and has been extensively studied in relation to ARDS. Again, there are no clinical trials examining the effect of PEEP on patients with corona virus induced ARDS.  In previous literature, a higher PEEP strategy has resulted in lower ICU and in hospital mortality8. The optimal level of PEEP is not known; rather, it varies patient to patient based on disease burden, lung compliance, risk of pneumothorax, and comorbidities. An arbitrary definition is to consider PEEP >10 a high PEEP strategy, while PEEP <10 is a low PEEP strategy2. Brigham and Women’s Hospital has a PEEP strategy based off BMI, where BMI <35 start on 10 of PEEP, BMI 35-50 start on 12 of PEEP, and BMI >50 receive a PEEP of 159.

Society of Critical Care Medicine recommends that patients with COVID-19 and moderate to severe ARDS should be proned for 12 to 16 hours per day. Proning ideally reduces the difference between dorsal and ventral transpulmonary pressures, decreases lung compression, and improves perfusion, ideally improving oxygenation10,11. A review and meta-analysis of >12 hours of proning in ARDS patients reduced mortality, though with increased risks of pressure injuries and endotracheal tube dislodgement or obstruction12. Support for initiation of prone ventilation in coronavirus ARDS is seen from a series of 81 COVID-19 patients where their radiologic pattern of disease progressed from ground glass opacities to basilar consolidation13. Another study of COVID-19 patients in the ICU demonstrated that proning was used in 11.5% of patients4. With proper training, proning can be easily implemented in many settings and should be started as early as in the emergency department for those presenting in severe ARDS requiring mechanical ventilation. Many institutions are now recommending early proning without a vasodilator trial9.

Traditionally, ARDS patients respond well to conservative fluid management, as seen by the landmark FACTT trial showing a decrease in the time on mechanical ventilation with this type of strategy14. Extrapolating this data to patients with coronavirus related ARDS is reasonable, especially when considering that that majority of these patients are elderly and may have underlying cardiac disease. Furthermore, early data on COVID patients has demonstrated that cardiac failure, in addition to or combined with, respiratory failure, contributes to 40% of COVID-19 fatalities15. This may indicate that myocardial depression and inability to tolerate fluids may be of significant importance in these patients.

Until recently, use of neuromuscular blockade in ARDS was routinely favored. However, the recent ROSE trial showed that a continuous infusion of paralytics did not improve mortality in patients with moderate to severe ARDS16. Therefore, Society of Critical Care Medicine suggests using intermittent boluses of paralytic versus a continuous infusion2. However, with persistent vent dyssynchrony, continuous paralytic infusion can be used for up to 48 hours2.

Most choices of initial ventilator settings in the ICU is subjective to provider preference, specific ICU culture, or respiratory therapist experience. Currently, the use of low tidal volume ventilation has been the strategy of choice for preventing ventilator induced lung injury in patients with ARDS. The Society of Critical Care Medicine Guidelines do not comment upon or specify ventilation modes for patients with coronavirus related ARDS. Commonly used for only refractory hypoxia, airway pressure release ventilation (APRV) may be another good option for patients with coronavirus related ARDS. Multiple studies demonstrate that APRV stabilizes alveoli and reduces the incidence of ARDS17, 18. Combining this with the notion that proning may be of increased benefit in these patients, Varpula et al. demonstrated greater improvement in gas exchange when prone positioning was combined with APRV rather than with SIMV19.Implementation of this ventilatory mode prior to the onset of severe ARDS in coronavirus may help to prevent the progression of ARDS and worsening hypoxia.

APRV Network has recently come out with rescue guidelines for time controlled adaptive ventilation (TCAV) in reference to APRV ventilation20. APRV involves setting four variables- Thigh, Tlow, Phigh, and Plow (See Figure 1 for setting information). This method can be used in spontaneously and non-spontaneously breathing patients. In ARDS, initial settings will vary depending on the severity of ARDS. The main difference in injured lungs will be increasing Phigh to facilitate maintenance of lung inflation, as well as shortening Tlow to control the amount of end expiratory lung volume. The theory behind Tlow is related to the idea that with worsening ARDS, the elastance, or recoil, of the lungs increases and shortens the necessary release time of APRV. Therefore, it is necessary to drop Tlow to maintain end expiratory lung volume and alveolar stability and prevent over emptying of the lungs.

Finally, refractory hypoxemia in patients with coronavirus ARDS after implementation of the above recommendations should suggest initiation of venovenous ECMO and prompt urgent consultation or transfer as feasible.

Figure 1: From APRV Rescue Guidelines (https://www.aprvnetwork.org/wp-content/uploads/2020/03/APRV%20TCAV%20Rescue%20Strategy%20Strategy%20Guidelines%202020.pdf).

References

  1. Wu Z, McGoogan JM, (2020) Characteristics of and Important Lessons From the Coronavirus Disease 2019 (COVID-19) Outbreak in China: Summary of a Report of 72314 Cases From the Chinese Center for Disease Control and Prevention. JAMA; doi: 10.1001/jama.2020.2648
  2. Alhazzani W, Hylander Moller M, Arabi YM, et al. Surviving Sepsis Campaign: Guidelines on the Managemetn of Critically Ill Adults with Coronavirus Disease 2019 (COVID-19). E-pub ahead of print.
  3. Yang X, Yu Y, Xu J, Shu H, Xia J, Liu H, Wu Y, Zhang L, Yu Z, Fang M, Yu T, Wang Y, Pan S, Zou X, Yuan S, Shang Y, (2020) Clinical course and outcomes of critically ill patients with SARS-CoV-2 pneumonia in Wuhan, China: a single-centered, retrospective, observational study. Lancet Respir Med;doi: 10.1016/S2213-2600(20)30079-5
  4. Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX, Liu L, Shan H, Lei CL, Hui DSC, Du B, Li LJ, Zeng G, Yuen KY, Chen RC, Tang CL, Wang T, Chen PY, Xiang J, Li SY, Wang JL, Liang ZJ, Peng YX, Wei L, Liu Y, Hu YH, Peng P, Wang JM, Liu JY, Chen Z, Li G, Zheng ZJ, Qiu SQ, Luo J, Ye CJ, Zhu SY, Zhong NS, China Medical Treatment Expert Group for C, (2020) Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med; doi:10.1056/NEJMoa2002032
  5. Wang D, Hu B, Hu C, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus–Infected Pneumonia in Wuhan, China. JAMA. 2020;323(11):1061–1069. doi:10.1001/jama.2020.1585
  6. Walkey AJ, Goligher EC, Del Sorbo L, Hodgson CL, Adhikari NKJ, Wunsch H, Meade MO, Uleryk E, Hess D, Talmor DS, Thompson BT, Brower RG, Fan E, (2017) Low Tidal Volume versus Non-Volume-Limited Strategies for Patients with Acute Respiratory Distress Syndrome. A Systematic Review and Meta-Analysis. Ann Am Thorac Soc 14: S271-S279
  7. Fan E, Del Sorbo L, Goligher EC, Hodgson CL, Munshi L, Walkey AJ, Adhikari NKJ, Amato MBP, Branson R, Brower RG, Ferguson ND, Gajic O, Gattinoni L, Hess D, Mancebo J, Meade MO, McAuley DF, Pesenti A, Ranieri VM, Rubenfeld GD, Rubin E, Seckel M, Slutsky AS, Talmor D, Thompson BT, Wunsch H, Uleryk E, Brozek J, Brochard LJ, American Thoracic Society ESoICM, Society of Critical Care M, (2017) An Official American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine Clinical Practice Guideline: Mechanical Ventilation in Adult Patients with Acute Respiratory Distress Syndrome. Am J Respir Crit Care Med 195: 1253-1263
  8. Briel M, Meade M, Mercat A, Brower RG, Talmor D, Walter SD, Slutsky AS, Pullenayegum E, Zhou Q, Cook D, Brochard L, Richard JC, Lamontagne F, Bhatnagar N, Stewart TE, Guyatt G, (2010) Higher vs lower positive end-expiratory pressure in patients with acute lung injury and acute respiratory distress syndrome: systematic review and meta-analysis. JAMA 303: 865-873
  9. Brigham and Women’s Hospital COVID-19 Critical Care Guidelines.
  10. Albert RK, Hubmayr RD, (2000) The prone position eliminates compression of the lungs by the heart. Am J Respir Crit Care Med 161: 1660-1665
  11. Nyren S, Radell P, Lindahl SG, Mure M, Petersson J, Larsson SA, Jacobsson H, Sanchez-Crespo A, (2010) Lung ventilation and perfusion in prone and supine postures with reference to anesthetized and mechanically ventilated healthy volunteers. Anesthesiology 112: 682-687
  12. Munshi L, Del Sorbo L, Adhikari NKJ, Hodgson CL, Wunsch H, Meade MO, Uleryk E, Mancebo J, Pesenti A, Ranieri VM, Fan E, (2017) Prone Position for Acute Respiratory Distress Syndrome. A Systematic Review and Meta-Analysis. Ann Am Thorac Soc 14: S280-S288
  13. Shi H, Han X, Jiang N, Cao Y, Alwalid O, Gu J, Fan Y, Zheng C, (2020) Radiological findings from 81 patients with COVID-19 pneumonia in Wuhan, China: a descriptive study. Lancet Infect Dis;doi: 10.1016/S1473-3099(20)30086-4
  14. National Heart L, Blood Institute Acute Respiratory Distress Syndrome Clinical Trials N, Wiedemann HP, Wheeler AP, Bernard GR, Thompson BT, Hayden D, deBoisblanc B, Connors AF, Jr., Hite RD, Harabin AL, (2006) Comparison of two fluid-management strategies in acute lung injury. N Engl J Med 354: 2564-2575
  15. Ruan Q, Yang K, Wang W, Jiang L, Song J, (2020) Clinical predictors of mortality due to COVID-19 based on an analysis of data of 150 patients from Wuhan, China. Intensive Care Med;doi: 10.1007/s00134-020-05991-x
  16. National Heart L, Blood Institute PCTN, Moss M, Huang DT, Brower RG, Ferguson ND, Ginde AA, Gong MN, Grissom CK, Gundel S, Hayden D, Hite RD, Hou PC, Hough CL, Iwashyna TJ, Khan A, Liu KD, Talmor D, Thompson BT, Ulysse CA, Yealy DM, Angus DC, (2019) Early Neuromuscular Blockade in the Acute Respiratory Distress Syndrome. N Engl J Med 380: 1997- 2008
  17.  Habashi NM. Other approaches to open-lung ventilation: airway pressure release ventilation. Crit Care Med. 2005;33:S228-S240. doi:10.1097/01.ccm.0000155920.11893.37.
  18. Zhou Y, Jin X, Lv Y, Wang P, Yang Y, Liang G, Wang B, Kang Y. Early application of airway pressure release ventilation may reduce the duration of mechanical ventilation in acute respiratory distress syndrome.
  19. Varpula T, Jousela I, Niemi R, et al: Combined effects of prone positioning and airway pressure release ventilation on gas exchange inpatients with acute lung injury. Acta Anasthesiol Scand 2003; 47: 516-524.
  20. APRV Network. APRV Rescue Guidelines 2020. https://www.aprvnetwork.org/wp-content/uploads/2020/03/APRV%20TCAV%20Rescue%20Strategy%20Strategy%20Guidelines%202020.pdf.

                 

Lindsay Ritter, MD

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