Ventilator curves. Fellowonderwijs 2 feb PDF Free Download

Ventilator curves Fellowonderwijs 2 feb 2012

Mechanical ventilation Supported Ventilator affects patients respiratory drive Monitor interaction patient - ventilator Controlled Monitor interatcion patient - ventilator

Waveform analysis Provide optimal ventilation Prevent adverse events of MV Most common: P,aw, flow, volume Advanced: Paralysis, P,es, P,ga, E,di

Control of breathing

Peripheral chemosensors Chest 2000

S"mulus transduc"on Pa,

Hypoxic drive in caro"d endarteryectomy ET-O2 5.3 kpa pre-op O2 response post-op O2 response 27 kpa

O 2 responsiveness of caro"d bodies

Central chemosensors

Effect of CO 2 on V E 2-5 L/min/mmHg change in Pco2

Pulmonary receptors stretch receptors

Chest wall and muscle receptors

Effectors

Mechanics of respiration

Equation of Motion (spontaneous) P,mus (t) = P,res (t) + P,el (t) P,mus (t) = R,rs * V (t) + E,rs * V,FRC (t) P,mus (t) = R,rs * V (t) + E,rs * V,EE (t) + PEEP,i

Equation of Motion (spontaneous) P,mus (t) = P,res (t) + P,el (t) P,mus (t) = R,rs * V (t) + E,rs * V,FRC (t) P,mus (t) = R,rs * V (t) + E,rs * V,EE (t) + PEEP,i Determines TV VE

Equation of Motion (mechanical vent) P,TOT (t) = P,mus (t) + P,aw P,aw = PTOT (t) - Pmus (t) P,aw = V (t) * Rrs + VFRC (t) *E,rs - P,mus(t)

Pressures applied to respiratory system

Function of pressure delivered by ventilator

Function of pressure delivered by ventilator Trigger variable

Function of pressure delivered by ventilator control variable Trigger variable

Function of pressure delivered by ventilator control variable cycle-off variable Trigger variable

1. Trigger variable Pressure Flow Volume Edi

Function of pressure delivered by ventilator control variable

2. Control variable (P or V ) Independent Dependent AVC volume, flow P,aw PC/PSV P,aw Volume, flow NAVA volume, flow, Paw

Function of pressure delivered by ventilator cycle-off variable

3. Cycle off variable Time (AVC, PC) Volume P,aw (PC, PS, VC) Flow (PS) E,di Ideally coincide with end neurla inspiration

Forms of asynchrony

Asynchrony

I. Waveforms in triggering phase 1. trigger delay 2. ineffective efforts 3. autotriggering

Waveforms in triggering phase

Dynamic hyperinflation Causes: Low elastic recoil respiratory system High TV, high RR Increased expiratory resistance Short neural expiratory time

Dynamic hyperinflation Consequences: 1. Elastic threshold load on inspiratory muscles P,mus (t) = R,rs * V (t) + E,rs * V,EE (t) + PEEP,i 2. Trigger delay / wasted efforts

Dynamic hyperinflation: trigger delay

Dynamic hyperinflation: wasted effort

Dynamic hyperinflation: wasted effort 1. Inspiratory muscle activity 2. Relaxation expiratory muscle 3. cardiac oscillations

Dynamic hyperinflation: wasted effort

P,aw less sensitive to detect asynchrony than V

P,aw less sensitive to detect asynchrony than V P,aw is less sensitive: (low circuit resistance during TE) P,aw = V E * R,exp,circuit P,aw = V E * Rexpcrircuit

Wasted effort during inspiration: ACV AVC controlled most sensitive

Wasted effort during inspiration: PSV most sensitive controlled

Asynchrony: APRV?

Prevention trigger delay / wasted efforts 1. Decrease hyperinflation 2. Increase Pmus during trigger phase (sedation) 3. Application PEEP,E 4. Decrease trigger threshold 5. Decrease inspiratory resistance (tube / bronchodilators)?

Autotriggering

Autotriggering Causes Low threshold Circuit leaks Water in tubings Cardiogenic oscillations (Hiccup) Not an issue in PAV or NAVA

Respiratory drive Initial P,aw decrease (isometric contraction)

Respiratory drive

II. Waveforms during pressurization / cycle off

Respiratory effort ACV: Independent variables: Flow and volume P,aw: dependent P,TOT (t) = P,mus (t) + P,aw = P,res (t) + P,el (t) P,aw = PTOT (t) - Pmus (t) P,aw = V (t) * Rrs + VFRC (t) *E,rs - P,mus(t)

Respiratory effort: ACV

Respiratory effort PSV / PC: Independent variables: P,aw Dependent: volume and flow => No relation between P,mus and P,aw! To asess effort: examine flow (and volume)

Respiratory effort: PSV

Respiratory effort: PSV 127 deg 138 deg 144 deg Interaction P,mus and T,insp: No effort: Ti depends on and V,th Effort: Ti unpredictable

constant flow: Inadequate support?

P,mus during AVC

Severe airway obstruction PSV 1. high R,aw 2. acute insp muscle relaxation 3. exp muscle activation

End inspiratory increase P,aw

Inspiratory rise time Overshoot in pressure screen dump

Expiratory asynchrony

Expiratory asynchrony Early cycle off

Expiratory asynchrony Elastic recoil > P,mus Early cycle off

Expiratory asynchrony Elastic recoil > P,mus Elastic recoil < P,mus Early cycle off

Expiratory asynchrony Elastic recoil > P,mus Elastic recoil < P,mus Early cycle off Causes: Low PS Short Tau, RS High V,th

Cycle off delay Causes: Excessive PS Long Tau, RS Low V,th

Waveform in expiration

Waveform in expiration Information on resistance

Waveform in expiration Information on resistance P,aw = V E * Rexp,circuit - PEEP

P,aw during expiration V E

Waveform in expiration Information on resistance P,aw = V E * Rexp,circuit - PEEP

Conclusion Curves provide information on P-V synchrony

Examples

Type of triggering?

Type of triggering? Zero flow Drop in pressure = Pressure triggering

Type of triggering? Zero flow Drop in pressure = Pressure triggering Flow trigering

PSV Flow triggering Wasted effort Trigger delay Increased R,aw

Type of asynchrony? What has been done to improve?

Type of asynchrony? What has been done to improve? PSV Flow triggering Wasted effort Trigger delay

Type of asynchrony? What has been done to improve? PSV Flow triggering Wasted effort Trigger delay (B) Reduced trigger threshold

What type of asynchrony? What would you do? tekst

What type of asynchrony? What would you do? tekst Higher insp flow (TV =) More time expiration

Autotriggering?

Interpret the waveform

Interpret the waveform PSV Autotriggering Ineffective efforts delayed cycle off exp muscle contraction

http://asynchrony.med.unipmn.it/index.php

Ventilator curves. Fellowonderwijs 2 feb 2012