ARDS Assisted ventilation and prone position ICU Fellowship Training Radboudumc
Fig. 1 Physiological mechanisms controlling respiratory drive and clinical consequences of inappropriate respiratory drive during acute respira-
In which patient should you worry? Tidal volume consistently > 6-8 ml/kg IBW in relation to ventilated lung volume Severe lung injury Obvious excessive inspiratory efforts - use of accessory muscles Transpulmonary pressure > 2-22 cm H2O, PTP > 2 P.1 > 3-4 cm H2O Low threshold for EAdi and Ppl measurement
P.1 Marker for respiratory drive and WOB (normal.5-1.5 cm H2O)
Therapeutic measures Lower the level of spontaneous effort Optimize patient-ventilator interaction Control the patient s respiratory drive Treat acidosis and hypoxemia + fever/pain Provide sufficient sedation and analgesia Use (partial) neuromuscular blockade Extracorporeal CO2 removal Apply sufficient PEEP to maximize fluid-like lung behavior
Explain what you see! (A) ( ) P aw (cmh 2 O) ( ) Flow (L/s) 4 1 ( ) P es (cmh 2 O) ( ) P L (cmh 2 O) -1 2 5 25-5 Peak Plateau ( ) Regional Lung Stretch ( Z) Nondependent ( ) Regional Lung Stretch ( Z) Dependent 2 7 6 Time (S) (B) ( ) P aw (cmh 2 O) ( ) Flow (L/s) 3 2 ( ) P es (cmh 2 O) ( ) P L (cmh 2 O) -2 18 2-1 Peak Plateau ( ) Regional Lung Stretch ( Z) Nondependent ( ) Regional Lung Stretch ( Z) Dependent 2 2 4 Time (S)
A recent case Male, 3 PMH: negative 22/9: admission with progressive dyspnea Diagnosis: metastasized nonseminoma testicular cancer
A recent case Chest X-ray admission CT scan 3/1
Patient 2/1 PSV: 6/6, Tv 65-7 ml RR: 2 P.1: 5 cmh2o Dynamic compliance 9-1 ml/cmh2o
PSV 6/6 Flow Pairway Pes TPP TDP EDi
Spontaneous breathing Flow Pes TPP TDP EDi
Work of breathing PSV 6/6 Spontaneous breathing WOB J/L (N.35) 3.16 3.64 WOB J/min (N 2.4) 58.23 62.27
22/1
A recent case 23/1: Passes SBT Extubation - transfer to intermediate care unit
Conclusion High respiratory drive in spontaneously breathing patients or on assisted ventilation may induce lung injury However, it is unclear exactly when P-SILI starts and has an impact on outcome Rethink your strategy when danger signs are present especially in inhomogeneous lungs with solid like behavior
Ventilator Induced Lung Injury Vigor spontaneous efforts Mechanical heterogeneity ph and vascular pressures Reduced lung capacity Stress / Strain Mechanical power Disease stage and VILI predisposition Mechanical heterogeneity
Rescue therapies Prone position NO or prostacyclin inhalation High frequency oscillation Extra corporeal life support
Difficulties with Oxygenation Adequate CO ino Prone Higher PEEP Recruitment Maneuvers Prone Position HFO When above strategies are ineffective consider VV-ECMO
Beneficial effects of prone position 2 P/F increase 27-39% 3 N = 29 Supine higher Prone higher 1 Day 1 Day 2 Day 3 Patients (%) 2 1 1 26 22 14 11 7 Meta-analysis N = 929 In total 7-8% of patients responded 3 3 3 < -4-4 - - 4 4-8 8-12 12-16 16-2 2-24 > 24 P/F response (mmhg) Sus S. Intensive Care Med 21;36:585-599 Gattinoni L. Crit care Med 23;31:2727-2733
Mechanical effects of proning Supine Prone 4 P <.5 NS P <.5 P <.5 3 32 32 Median 2 24 25 1 1 11 14 15 Ecw (cmh2/l) El (cmh2o/l) Pplat (cmh2o) Rl (cmh2o/l/s) Riad Z. Am J Respir Crit Care Med 218
Prone position in patients with ARDS All evidence points to the fact that in the prone position blood flow is greatest in the dorsal (non-dependent) parts demonstrating the importance of the arterial tree Total ventilation may increase by a more homogenous pleural pressure and by eliminating the weight of the heart and liver
Reduction in pleural gradient with proning
The position of the heart
Prone position in severe ARDS MC (27) RCT Severe ARDS and MV < 36 hrs with PF < 15 mmhg, FiO2.6 and PEEP 5 Tv 6 ml/kg PBW After inclusion stabilization period of 12-24 hrs Guérin C. N Engl J Med 213
Prone position in severe ARDS Prone for at least 16 consecutive hrs PEEP and FiO2 from table: Pplat < 3 and ph 7.2-7.45 Clear criteria for stopping prone position (P/F 15 + PEEP 1 + FiO2.6 in supine position Strategy followed for up to 28 days Proning as rescue in the supine group strictly controlled Guérin C. N Engl J Med 213
Prone position in severe ARDS Supine (N = 229) Prone (N = 237) 1 P <.1 P <.1 P <.1 75 8,5 65 5 25 32,8 41 23,6 16 Mortality D28 Mortality D9 Extubation D9 Better oxygenation and less rescue therapy in prone group Main cause pneumonia - 4 ± 4 prone sessions Guérin C. N Engl J Med 213
Prone position - metaanalysis Sus S. CMAJ 214;186:E381
Prone position - metaanalysis Homogenous distribution of lung stress along the vertical gradient Beitler JR. Intensive Care Med 214;4:332-341
Prone position and RV failure Before PP After 18 h of PP P-value SAP (mm Hg) 115 ± 12 117 ± 14 NS HR (bpm) 17 ± 15 1 ± 13,19 CI (l/min/m 2 ) 2.9 ±.8 3.4 ±.8,13 RVEDA/LVEDA.91 ±.22.61 ±.21 <,1 Septal eccentricity 1.5 ±.2 1.1 ±.1 <,1 TR (n) 2 7 LVEDV (ml) 45 ± 13 64 ± 21 <,1 LVEF (%) 58 ± 11 6 ± 9 NS N = 21 Severe ARDS PF < 1 Veillard-Baron A. Chest 27;132:144-1446
Adverse effects? Pressure ulcers (RR 1.29 [1.16,1.44]) ET obstruction (RR 1.58 [1.24,2.1]) Thoracostomy tube dislodgement (RR 3.14 [1.2,9.69]) Sus S. Intensive Care Med 21;36:585-599
Prone position and ICP N = 11 3 25 2 kpa 15 1 5 Supine Prone 1 min Prone 1 h Prone 3 h Supine 1 min Supine 1 h PaO2 PaCO2 Thelandersson A. Acta Anaesthesiol Scand 26;5:937-941
Prone position and ICP N = 11 mm Hg 1 9 8 7 6 5 4 3 2 1 Supine Prone 1 min Prone 1 h Prone 3 h Supine 1 min Supine 1 h ICP CPP Thelandersson A. Acta Anaesthesiol Scand 26;5:937-941