Mechanical Ventilation for Dummies Keep It Simple Stupid

Transcription

1 Mechanical Ventilation for Dummies Keep It Simple Stupid Indications Airway Ventilation failure (CO2) Hypoxia Combination Airway obstruction Inability to protect airway Hypoxia (PaO 2 < 50) Hypercapnia (PaCO 2 > 50) Respiratory distress (RR > 30, use of accessory muscles)

2 Ventilator Management Scalar CMV ACV IMV SIMV SIMV + PS PCV IRV PRVC APRV CPAP Control Mode- Scalars (Volume- Targeted Ventilation) Preset Peak Flow Dependent on C L & R aw Preset V tt Essentials of of Ventilator Graphics T im e (s e c ) F lo w (L/min) P r e s s u r e (cm H 2 O) V o olu m e e (ml) 2000 RespiMedu CLINICAL UTILITY OF VENTILATOR GRAPHICS Vijay Deshpande, MS, RRT, FAARC

3 Ventilator Management Loops Pressure-Volume Loops Flow-Volume Loop V T Inspiration Volume (ml ml) Expiration Expiration Expiration Expiration Inspiration Inspiration Inspiration Inspiration Flow (L/min) 4 FRC 1 3 Volume (ml) Essentials of of Ventilator Graphics P aw aw aw (cm aw H 2 O) O) PIP 2000 RespiMedu Essentials of of Ventilator Graphics Expiration RespiMedu CLINICAL UTILITY OF VENTILATOR GRAPHICS Vijay Deshpande, MS, RRT, FAARC

4 Ventilator Management This really is all there is to it Time (RR) Volume (Vt) Pressure (PIP, P plat ) Flow Volume vs Time Scalar Inspiratory Tidal Tidal Volume Volume (ml) Inspiration Expiration TI TI Time (sec)

5 Ventilator Management Control Mechanical Ventilation Time Set respiratory rate Volume Set Vt Flow Set to deliver the Vt } Independent Variables Airway Pressure Dependent on the interaction of the above and on the respiratory system compliance and airflow resistance

6 Ventilator Management Pressure Control Ventilation Time Set respiratory rate Pressure Set pressure Flow Set to deliver pressure } Independent Variables Volume Dependent on the interaction of the above and on the respiratory system compliance and airflow resistance

7 Ventilator Management Dual Control Modes - PRVC Time Set RR Volume Set V T Flow Set } Independent Variables Pressure increases or decreases to maintain the set V T (Dependent variable), but this is Limited (i.e. controlled)

8 Airway Pressure Release Ventilation APRV-BILEVEL SIMV CPAP is transiently decreased or released to a lower level during expiration. Advantages 1. Lower Paw for a given V T 2. Lower V E, i.e., less dead space 3. Limited adverse effects on cardiac function 4. Spontaneous breathing 5. Decreased sedation Potential Disadvantages 1. Volumes change with changes in compliance and resistance 2. New technology 3. Limited access to technology 4. Limited research and clinical experience

9 Ventilator Management Peak Insp Pressure (PIP) vs. Plateau airway pressure (P plat) Transairway pressure PIP-Pplat Obstruction Secretions RAD P aw aw (cm H 2 O) Components of Inflation Pressure A 1 2 B PIP P plat plat /Alveolar Pressure A. Airway Resistance B. B. Distending Pressure Time (sec) Begin Inspiration Begin Expiration CLINICAL UTILITY OF VENTILATOR GRAPHICS Vijay Deshpande, MS, RRT, FAARC

10 Ventilator Management Compliance Relationship of volume to pressure Dynamic vs static Lung Compliance Changes in the P-V Loop V T Volume Targeted Ventilation Volume (ml( ml) COMPLIANCE Normal Increased Decreased Essentials of of Ventilator Graphics P aw aw aw aw (cm H 2 O) O) PIP levels 2000 RespiMedu CLINICAL UTILITY OF VENTILATOR GRAPHICS Vijay Deshpande, MS, RRT, FAARC

11 History of Mechanical Ventilation Poliomyelitis Negative pressure (iron lung) WW II Positive pressure cycled (Bennett and Bird) Volume cycle (Emerson) V T 6-8 ml/kg, Sigh ml/kg V T 10-15ml/kg without sighs ARDS & PEEP Ashbaugh Bigelow and Petty UCHSC 1967

12 Ventilator Induced Lung Injury VILI is due to volume (Overdistension) Ventilation 45 cm H 2 O Baseline 5 min 20 min Dreyfuss Am. Rev. Respir. Dis. 1998; 137:

13 ARDS is Not Homogeneous Gattinoni L. Milan Italy

14 Inflection Points Paw increases with little change in the volume Lower Lung Compliance Changes in the P-V Loop Upper Overdistension V T Volume Targeted Ventilation P aw rises aw with little or or no change in in V T Volume (ml( ml) COMPLIANCE Normal Increased Decreased P aw aw (cm H 2 O) O) PIP levels Pressure (cm H 2 O) Essentials of of Ventilator Graphics P aw aw aw (cm aw (cm H 2 O) 2 O) RespiMedu Essentials of of Ventilator Graphics RespiMedu CLINICAL UTILITY OF VENTILATOR GRAPHICS Vijay Deshpande, MS, RRT, FAARC

15 ARDSnet NIH NHLBI ARDS Clinical Trials Network

16 ARDS Network: ARMA Respiratory Management in ARDS 6 vs. 12 ml/kg Tidal Volume Mode: Volume Assist / Control Rate: Set rate < 35; adjust for ph goal = Oxygenation PaO 2 = mmhg SaO 2 = 88-95% PEEP FiO I:E = 1: Weaning by Pressure Support when PEEP/FiO2 < 8/.40 New Eng J Med 2000; 342: 1301

17 ARDS Network: ARMA Respiratory Management in ARDS 6 vs. 12 ml/kg Tidal Volume 12 ml/kg Group Initial Vt = 12 ml/kg IBW If Pplat > 50 cmh20, reduce Vt by 1 ml/kg. Minimum Vt = 4 ml/kg If Pplat < 45 cmh20 and Vt < 11 ml/kg, increase Vt by 1 ml/kg. 6 ml/kg Group Initial Vt = 6 ml/kg IBW. If Pplat > 30 cmh20, reduce Vt by 1 ml/kg. Minimum Vt = 4 ml/kg. If Pplat < 25 cmh20 and Vt < 5 ml/kg, increase Vt by 1 ml/kg. New Eng J Med 2000; 342: 1301

18 ARDS Network: ARMA Respiratory Management in ARDS 6 vs. 12 ml/kg Tidal Volume cm water ml/kg 12 ml/kg Plateau Pressure * * * * Study Day New Eng J Med 2000; 342: 1301

19 ARDS Network: ARMA Respiratory Management in ARDS 6 vs. 12 ml/kg Tidal Volume P/F 160 * * * PEEP (cm water) * * 6 ml/kg 12 ml/kg ml/kg 12 ml/kg Study Day Study Day New Eng J Med 2000; 342: 1301

20 ARDS Network: ARMA Respiratory Management in ARDS 6 vs. 12 ml/kg Tidal Volume Vt 6 vs. 12 ml/kg Mortality 31.0 vs 39.8% New Eng J Med 2000; 342: 1301

21 ARDS Network: ALVEOLI High vs. Low PEEP Ventilator management the same as ARMA except PEEP Lower PEEP/ Higher FiO 2 Treatment Group FiO PEEP Higher - PEEP/Lower FiO 2 Treatment Group FiO PEEP N Engl J Med 351:327, July 22, 2004

22 ARDS Network: ALVEOLI High vs. Low PEEP Variable Day 1 Day 3 Day 7 Low High Low High Low High PEEP P/F N Engl J Med 351:327, July 22, 2004

23 ARDS Network: ALVEOLI High vs. Low PEEP Conclusions VT goal 6 ml/kg Pplat limit of 30 cm H2O, Outcomes are similar whether lower or higher PEEP levels are used. N Engl J Med 351:327, July 22, 2004

24 ARDS Network: FACTT Fluids and Catheter Treatment Trial PAC vs. CVP N Engl J Med 354:2213, May 25, 2006

25 ARDS Network: FACTT Conservative vs. Liberal Fluid N Engl J Med 354:2564, June 15, 2006

26 D ARDS Network: FACTT Conservative vs. Liberal Fluid Furosemide mg/d Intake ml/d Output ml/d Balance ml/d Liberal Conserve Liberal Conserve Liberal Conserve Liberal Conserve N Engl J Med 354:2564, June 15, day fluid balance

27 ARDS Network: FACTT Conservative vs. Liberal Fluid N Engl J Med 354:2564, June 15, 2006

28 ARDS Network: FACTT Conservative vs. Liberal Fluid Outcome Liberal Conserve P Death 28.4% 25.5% 0.30 (60d) VFD (28d) ICU-FD (28d) Dialysis (60d) N Engl J Med 354:2564, June 15, 2006

29 ARDS Network: LASRS Late ARDS Steroid Rescue Study Methylprednisolone 2 mg/kg load 0.5 mg / kg q 6 for 14d, 0.5 mg / kg q 12 for 7d, Taper over 4 days Taper over a 2 days if septic shock Intensive infection surveillance 28.6 v 29.2% New Eng J Med Volume 2006; 354:

30 ARDS Network: LASRS Late ARDS Steroid Rescue Study Placebo (91) MP (89) p Mortality (60d) 28.6% 29.2% 1.0 VFD (28d) ICU FD (28d) Myopathy (no.) Infections / pts 43/30 25/20.14 Amylase (D7) Glucose (D7) New Eng J Med Volume 2006; 354:

31 Institute for Healthcare Improvement (IHI) Ventilator Bundle HOB > 30 o DVT prophylaxis PUD Prophylaxis Daily sedative vacation and assessment of readiness to extubate

32 Mechanical Ventilation Weaning What was the reason for intubation? Has that reason been resolved? Can patient protect airway? Can patient handle secretions? Oxygenation? Ventilation? (CO2) Others: Cardiac function, acid base, abdomen, renal function 35% prediction You will never find a fever if you do not measure a temperature?

33 Nonphysicain Directed Weaning Protocol Ordered Ely AmJRCCM 1999; 159: 439 Kollef CCM 1997; 25: 567

34 Daily Sedative Vacation Control Vacation Kress New Eng J Med 2000

35 Mechanical Ventilation Weaning Pressure Support Gradual reduction in ventilator work is assumed by the patient SIMV + PS Some breaths are ventilator work and some are patient work T-piece Discontinuation of ventilator work is assumed by patient. PSV Brochard AJRCCM 1994; 150: 896 SBT q d Esteban NEJM 1995; 332: 345

36 Mechanical Ventilation Failure to Wean Increase in demands Abnormal respiratory mechanics RAD Decrease C Unresolved infection Fever = Me = work Decrease in patient capability Sedation Weakness Malnutrition Neuro- or Myo-pathy Chest wall mechanics Demands Total Support Deleterious work Capability Ventilator Independence Tolerable load

37 Weaning Guidelines Daily assessment of potential Spontaneous breathing trials ( min) Stable support between SBTs Ability to protect airway Reverse causes of failure Weaning protocols for nonphysician Prolonged ventilation=slow gradual lengthening of SBTs Chest 2001; 120: 375S

38 Mechanical Ventilation Weaning Withdrawl of the ventilator Test for successful extubation Vt 5-7 ml/kg RR < 30 Me < 15 L RR/Vt < 105 NIF < 20 FVC ml/kg 10% Failure

39 Questions? KISS