Prone Position in ARDS

Transcription

1 Prone Position in ARDS Rich Kallet MS RRT FAARC, FCCM Respiratory Care Services San Francisco General Hospital University of California, San Francisco, Case Study A 39 yo F admitted to SFGH TICU s/p hanging, cardiac arrest, massive aspiration, severe hypoxemia, asynchrony and hemodynamic instability. Pre-prone management: PEEP: +15, F io2 :.9 NMBA & Aeroprost 5 ng/kg/m V T : 53 ml (8.5); V E :17L/m Pplat: 31 cmh 2 O; Crs: 33 ml/cmh 2 O ABG: 7.28 / 66/ 15 P/F = 117 ; V D /V T =.92, a/ap O2 = Percent Contribution of Ventral-Dorsal Lung Level to Total Area of the Lung by CT Analysis %.1 SP P1 P2 P3 a/apo2 Vd/Vt 1h 2h 2h 25% 65% P/F FiO Gattinoni Anesthesiology 1991 Pulmonary Stress-Strain: Supine vs. Prone Position Increased Dorsal:Caudal Ventilation with Prone Position PRONE SUPINE Broccard et al. Crit Care Med 2 1

2 Prone Positioning as LPV Nonaerated Inflammatory cell activity present throughout the lungs independent of the inflation status. homogenizing alveolar V distribution should lessen regional overdistension ( stress amplifiers ) Supine Prone: Non-Dependent Well Aerated Dependent Supine Prone Galiatsou 26 Overinflation Gattinoni,213 Prone Positioning Greatly Reduces Pro-Inflammatory Mediator Release in ARDS Chan (27): RCT (N=22) ARDS-CAP, 72h Mortality on ARDS Day 14 predicted by IL-6 (378 vs. 26 pg/ml) Effect of Prone Position on IL-6 Expression BL H-24 H-72 SP 196 Complexity of Pulmonary Perfusion Distribution Whole Lung Level: Gravity: Hydrostatic Pressures lung tissue dorsal-caudal regions vascularity perfusion/unit lung volume (upright position) Intermediate Level: Vascular tree geometry dominant 23 generations uneven branching angles/diameters that mimic airway structures (fractal geometry) Heterogenous perfusion within horizontal tissue plane as well as vertical zones Perfusion is largely independent of gravity : regardless of body posture, perfusion is always greater in dorsal lung regions (an anatomical flow bias favoring dorsal perfusion that is further enhanced by increased dorsal NO production) N = 735 Impact of in ARDS (33 observational studies since 1976) Responders: 8% [57-1%] + Response both in Early & Late ARDS PROSEVA Study + Response both in ARDS pulm & ARDS extpulm Pa O2 : 4 [26-52]; Pa O2 /Fi O2 : 67 [8-161] Low incidence of adverse hemodynamic effects (2-4%) secretion mobilization some patients Mixed results: effects on Pa CO2, Crs, EELV Multi-center RCT N = 466: 9 Day mortality 41 to 24% Adjusted RR for mortality.48 (SOFA); VFD 4 & 14 (D-28,D-9) No difference in complication rates N Engl J Med 213 2

3 11 RCTs comparing to SP Pre-LPV, varying duration, varying ARDS severity/etiology PROSEVA study: 1 st RCT + mortality benefit Meta-analysis studies varied: reviewing 7, 9, 1 & 11 RCT s Sud (21) : 1 studies; N = 1867, Mortality P/F < 1 (RR:.84) effect up to P/F = 14 P/F: 27-39% over 3 days; Pressure Ulcer (RR: 1.29) ETT obstruction (RR: 1.58) Lee (214) 11 studies; N = 2246 Mortality (RR:.77); # to Tx: 16 * > 1h (RR:.62) + Effect: P/F < 15 (RR:.72) Pressure Ulcer (RR: 1.49) ETT obstruction (RR: 1.55) Beiter (214): 7 studies ; N = 2119 Mortality (RR:.66) only when V T < 8 ml/kg Baseline VT 1mL/kg PBW, Mortality risk 16.7% > 12h/day Mortality (RR:.71) Hu (214): 9 studies; N = 2242 Mortality P/F < 1 (RR:.71); PEEP> 1 (RR:.57) > 12h/day (RR:.54) Prone Positioning,PEEP, RM: Manifestation of CREEP! Progressive in pulmonary volume occurring under constant airway pressure (lungs & chest wall). Viscoelastic property* of tissue that yield their shape over time under constant stress Slow gradual in Oxygenation *think of the properties of caramel or drying glue Van de Woestijne 1967, Respir Physiol Recruitment = Pressure x Time Dynamic process, variable time course. Increased Time Enhances Oxygenation 25% Early (< 4h); Late? No plateau in P/F after 8h Responders Time Required: Viscosity = time necessary to open sequentially collapsed airways & alveoli Paw needed to recruit collapsed small airways is determined by: Non-Responders Viscosity, thickness, surface tension of the airway lining fluid, airway radius, axial wall traction exerted by the surrounding alveoli, presence of surfactant. Reutershan Clin Sci 26 3

4 Enhances Effectiveness of PEEP in ARDS Grannier et al Intensive Care Med 23 Enhances Inhaled Vasodilators in ARDS Pa O2 / Fi O2 SP Qs/Qt SP SP SP+NO +NO PaO2/FiO2 PVR Johannigman Effect of Adding RM to Prone Positioning on PaO2/FiO2 in ARDS SP -6h -RM RM+3 RM+18 Prone Positioning Unloads the Right Ventricle & Decreases PFO-Related Shunt Cor-Pulmonale: 22% of ARDS cases ARDS+Cor-Pulmonale 6% vs. 36% Mortality in ARDS pts w/ Cor-Pulmonale 33% RV size/ 18h in ; CI 2.9 to 3.4 Associated w/ oxygenation, ventilation, Crs PFO: ~2% of ARDS case related to Cor-Pulmonale Case Report of severe PFO by TE-Echocardiography immediate in bubble emboli transversing artia & Pa O2 /Fi O2 59 to 278 mmhg; Pa CO2 54 to 3 mmhg Oczenski Crit Care Med 25 Viellard-Baron 27 Cor Pulmonale; Legras 1999 PFO Lung recruitability with in ARDS has stronger association with Pa CO2 than Pa O2 /Fi O2 Obesity and Prone Position Protti, Intesive Care Med 29 P/F SP P/F BMI 25 BMI 38 De Jong 213 4

5 Screening Criteria for : Trial of PEEP: cmh 2 O in Patients with Pa O2 /Fi O2 < 15 on Fi O2 >.6 Frequency Distribution of Critical Opening Pressure in 2 Patients with ARDS Superimposed hydrostatic pressure in ARDS Superimposed hydrostatic pressure + CW Pressure in ARDS Patients that have brisk oxygenation response to moderately high PEEP within a few hours don t require Cressoni 214 Set PEEP = LIP cmh 2 O Summary significantly oxygenation 8% of ARDS Early application w/ LPV & > 12h mortality Enhances PEEP, RM, inhaled Vasodilators Enhances LPV (max recruit, min overdistension) Enhances Secretion clearance in some patients Skin erosion is a significant problem Hemodynamic AE s and catheter loss relatively infrequent 5