Acute Respiratory Distress Syndrome (ARDS): What You Need to Know - PowerPoint PPT Presentation

Acute Respiratory Distress Syndrome (ARDS): What You Need to Know Today John Gallagher DNP, RN, CCNS, RRT Andrew Rice MSN,CRNA, ACNP-BC

Learning Objectives • Identify current trends in the clinical management of ARDS during the COVID-19 Pandemic • Make recommendations for caring for patients with ARDS during the COVID-19 Pandemic

Coronavirus (COVID-19) • Novel bat-origin Coronavirus originating in Wuhan, Hubei, China – SARS-CoV-2 aka COVID-19 • Patients present with flu-like symptoms – Sore throat – Cough – Fever – Shortness of breath

COVID-19 Illness Severity • 81% Mild (no or mild pneumonia) • 14% Severe disease – Dyspnea, hypoxia, >50% lung involvement • 5% critical disease – Respiratory failure, shock, or multiorgan dysfunction – Uncommon: only 13% need vasoactive agents

COVID-19 Related ARDS • 3% – 17% COVID-19 develop ARDS • Late onset dyspnea (6.5 days) • ARDS develops ~2.5 days after dyspnea • Risk Factors: age, smoking, comorbidities, fever > 39*C – Cardiac disease, DM, HTN, lung disease, CKD, cancer, obesity

Lab Findings with Worse Outcomes • Lymphopenia • Elevated liver enzymes • Elevated lactate dehydrogenase (LDH) • Elevated inflammatory markers (eg, C-reactive protein [CRP], ferritin) • Elevated D-dimer (>1 mcg/mL) • Elevated prothrombin time (PT) • Elevated troponin • Elevated creatine phosphokinase (CPK) • Normal procalcitonin with pneumonia, but elevated with ICU admission • Acute kidney injury

Patient Presentation • Hypoxemia manifested by low oxygen saturation worsening with activity (hypoxic vasoconstriction?) – SpO2 < 90% • High negative inspiratory effort in spontaneously breathing patients • Improvement in oxygenation with invasive positive pressure ventilation – Lung compliance may be normal!!

Patient Presentation • Worsening hypoxemia and lung compliance • Hypoxic pulmonary vasoconstriction/microemboli – Elevated D-dimer • Cardiomyopathy/Myocarditis – Viral cause – Right ventricular failure related to ARDS and PPV?

ARDS Criteria PaO 2 /FiO 2 Ratio Mild* Moderate* Severe* 200 – 300 100 - 200 < 100 * on CPAP/PEEP > 5 cm H 2 O • Acute onset (within 7 days) • Bilateral opacities (CXR or CT) • Alveolar edema is not related to cardiac failure or fluid overload – Does not require normal PCWP – Does not require absence of LA hypertension JAMA. 2012;307(23):2526-2533. doi:10.1001/jama.2012.5669

Radiologic Changes • Radiologic changed may be seen early in some cases before positive COVID screening results • Not recommended: CXR or CT for screening/progression (staff/equipt contamination) • Ground glass opacities peripherally and basilar • Interlobular septal thickening

Lung Ultrasound • Thickened/Irregular pleural line • Multiple B-Lines • Subpleural consolidations • Air bronchograms B-Lines • Localized pleural effusion possible Copetti, R Cardiovasc Ultrasound 2008

COVID-19 Supportive Management • Prone ventilation (prolonged, avoid early return to supine) • Conservative fluid therapy (except with sepsis) • Glucocorticoids? • Avoid aerosolization procedures (bronchoscopy, nebulizers) • Critical Care Management: nutritional support, VTE prophylaxis, stress ulcer prophylaxis, fever management, etc. • Low intubation threshold

Management of Hypoxemia • Supplemental low-flow oxygen – Lowest FiO2 necessary maintain SpO2 90% – 96% • High-flow nasal Cannula? • Non-invasive positive pressure ventilation (NIPPV) ? • Intubation/Invasive PP ventilation

Non-Invasive Strategies • HFNC – Aerosol virus • Mask over the face • NIPPV – Aerosol virus • Filtration of the circuit

Non-Invasive Strategies –CPAP Hood – High Flow Set Up – Venturi

Decision to Intubate • Delayed intubation  ↑ risk to patient and HCW • Low Intubation threshold – Rapid ARDS progression (hours) – Lack of improvement on >40 L/minute of high flow oxygen and a fraction of inspired oxygen (FiO 2 ) >0.6 – Worsening hypercapnia – Hemodynamic instability or multiorgan failure

Intubation-Preparation • PPE- Full barrier precautions – PAPR (powered air purifying respirator) or N-95 mask/faceshield • Avoid awake intubation (cough aerosolization) • Most experienced operator/Limit those in the room (Neg press) • Video laryngoscope (distance and first pass success) https://www.nejm.org/doi/full/10.1056/NEJMc20075 • Novel barrier approaches 89?query=featured_coronavirus Barrier enclosure during endotracheal intubation April 3 rd 2020 https://www.apsf.org/wp-content/uploads/news-updates/2020/apsf-coronavirus-airway-management-infographic.pdf

Intubation • Goals: Protect staff, successful first attempt, limit aerosolization • Pre-oxygenate 5 min (passive low-flow ie. nasal cannula) • RSI intubation – Do Not Mask Ventilate • Heat Moisture Exchanging Filter (HMEF) between airway and BVM/Ventilator • Direct placement on the ventilator https://www.apsf.org/wp-content/uploads/news-updates/2020/apsf-coronavirus-airway-management-infographic.pdf

ARDS Criteria PaO 2 /FiO 2 Ratio Mild* Moderate* Severe* 200 – 300 100 - 200 < 100 * on CPAP/PEEP > 5 cm H 2 O • Acute onset (within 7 days) • Bilateral opacities (CXR or CT) • Alveolar edema is not related to cardiac failure or fluid overload – Does not require normal PCWP – Does not require absence of LA hypertension JAMA. 2012;307(23):2526-2533. doi:10.1001/jama.2012.5669

Zone of ↑ Risk

PLATEAU Driving Pressure PEEP

Alveolar Overdistension

Collapsed Alveoli ฀ R epeated A lveolar C lose and E xpansion (RACE) ฀ “ Milking ” of surfactant from alveoli with repeat closure Inspiratory phase Expiratory phase

Lung Protection Marini, J. (2019) Critical Care, 23 (suppl 1):114

Lung Protective Ventilation Strategy • Maintain Alveolar Pressure (plateau pressure) < 30 cm H 2 O – Low tidal volume ventilation 6 ml/kg of PBW (range 4-8 ml/kg PBW) • PEEP to prevent end-tidal collapse/recruit – PEEP start lower (8-10 cm H 2 O) and titrate up

ARDSNet Protocol • Low tidal volume • Prone ventilation http://www.ardsnet.org/files/ventilator_protocol_2008-07.pdf

Evolution of Mechanical Ventilators

Pressure Control Volume Control A/C A/C SIMV PEEP SIMV Support Dual Control

Ventilation Strategies • LTVV + PEEP • Pressure Control Inverse Ratio (PC-IRV) + PEEP • Volume Targeted Pressure Modes • Biphasic Ventilation- spontaneous breathing mode – BiPhasic/BiLevel – Airway Pressure Release Ventilation ( exp time < 1.0 sec)

Volume Targeted (Control)Ventilation (VCV) • Guaranteed tidal volume with each breath • Constant flowrate • Pressure varies based on resistance and compliance of the lung and chest wall Pressure Flow

Pressure Targeted (Control) Ventilation (PCV) Fixed inspiratory pressure but Volume is variable • Inspiratory pressure & inspiratory time • Airway resistance, lung and chest wall compliance Pressure Flow

Pressure Control Inverse Ratio (PC-IRV) Pressure 50 25 E-Time I-Time I-Time 5 0 Time

Auto-PEEP Pressure 50 25 E-Time I-Time I-Time 8 Auto- PEEP 5 Set PEEP 0 Time

PCV PC-IRV Actual PEEP P Auto PEEP Measurement F Exp. Flow 50 - 80% of Peak

Volume Assured Pressure Modes Pressure Limited + Minimum Volume Guarantee • aka … – Adaptive Pressure Control Modes – “ Dual Control ” Modes Machine adjusts to changing lung mechanics to provide tidal volume within pressure limit

Volume Assured Pressure Modes •Pressure Regulated Volume Control (PRVC) •Volume Support •Volume Control Plus (VC+) PCV + Volume Target •Volume Support •Pressure Control Volume Guarantee (PCVG) •Volume Targeted Pressure Control (VTPC) •Adaptive Pressure Ventilation •Adaptive Support Ventilation •Pressure Augmentation

Pressure Regulated Volume Control Pressure Flow

Points to Remember • Guaranteed minimum tidal volume but not a constant tidal volume!! • Tidal volume may not be achieve if lung compliance becomes low or pressure limit is set too low • Excessive tidal volume if the patient generates excessive inspiratory efforts

APRV † Spontaneous Breaths * Synchronized Transition * * * * * * * † † † PEEP HI P PEEP LO T BiPhasic Spontaneous Breaths PEEP HI Spontaneous Breaths P PEEP LO T

Biphasic Ventilation • Biphasic •Inspiratory Pressure Limit (PEEP HI ) • Bi-level •PEEP (PEEP LOW ) • Bi-Vent •Inspiratory time (T i ) • BIPAP •Rate (f x ) • Duo PAP •Pressure Support Spontaneous Breaths PEEP HI Spontaneous Breaths P PEEP LO T

APRV Characteristics • High CPAP level with a short expiratory releases at set intervals (rate) • APRV always implies an inverse I:E ratio • All spontaneous breathing is done at upper pressure level Spontaneous Breaths † * Synchronized Transition * * * * * * * † † † PEEP HI P PEEP LO T

Alveolar Volumetric Changes in APRV Conventional APRV Exp. ~ Insp. Exp. ~ Insp.