Home Care/ Ventilatory Support for the Spontaneous Breathing Patient

Bill Lamb, BS, RRT, CPFT, RCPDirector of Clinical Services, Bemes Home Medical, Inc.

Manager of Field Operations, Bemes, Inc., Respiratory & Critical Care Services

Disclosures

• Bemes, Inc. has relationships with TYCO HealthCare/ Puritan Bennett, Percussionaire & ResMed

Objectives

• Review the Spontaneous breathing process in ventilatory support

• Discuss phases of the spontaneous breath and conditions that may cause patient ventilator asynchrony

• Review E sens, rise time, • Discuss Home Care Ventilatory support wish list: ATC,

VS, PRVC, Proportional Assist Ventilation

Patient Ventilator Asynchrony often occurs during the spontaneous breathing process

• When & Where can it occur?

Pre trigger

Post trigger

Pressure

Time

Patient Ventilator Synchrony

• Mechanical ventilation modes that permit spontaneous ventilatory activity are called “interactive” modes.

• Patient/ ventilator interaction includes:– Simple triggering of mandatory breaths

– Processes affecting delivered flow patterns during inspiratory phase

– Breath timing

– Spontaneous breathing

Patient Ventilator Interaction

• Synchronous patient - ventilator interactions reflect that the ventilator is sensitive to the initiation, response (breath delivery) and termination of the patients ventilatory effort

• Dysynchronous (asynchronous) patient ventilator interactions occur when the ventilator fails to adequately respond to the patients ventilatory needs & or breathing pattern

Ventilation for Sub-Acute to Home

Achieva® by Puritan Bennett

LTV 950® by Pulmonetic a division of Viasys

T-Bird Legacy® by Viasys

HT50® by Newport MI

examples

Evidence: Prevalence of Patient Ventilator Asynchrony

• CHEST Aug 1994

• Voran, Joseph

• Baylor College of Medicine, Houston TX

Prevalence of Patient Ventilator Asynchrony

• Methods: 30 patients requiring mechanical ventilation for acute respiratory failure admitted to the MICU

• Exclusion Criteria: patients under neuromuscular blockade, heavy sedation, drug overdose, or with hemodynamic instability

Prevalence of Patient Ventilator Asynchrony in Critically Ill Patients

• Methodology:– Asynchrony index determined comparing the number

of synchronous breaths versus the number of asynchronous breaths for each ventilated patient in the study

– Data presented at CHEST 1994

– Note: these patients had cuffed ETT or Tracheostomy tubes with inflated cuffs. Imagine the potential for asynchrony in the home with leaks in the airway & etc.

Prevalence of Patient Ventilator Asynchrony in Critically Ill Patients

• Asynchrony index: – All but one patient had asynchronous breaths– Mean asynchrony Index (% of breaths that were

asynchronous) was 36.4% (median 30.6%)– Mortality significantly higher in those patients with

higher A.I. (statistically significant)• Patient/Ventilator Asynchrony can cause poor outcome • In the Home, Pt/ Vent asynchrony could cause poor

outcome and can cause demand on our delivery systems (e.g. Frequent calls for RT to come assess; trips to the ER, etc)

Difficulty Triggering a Breath

• Symptoms:– Patient agitation– Increased respiratory rate– Sub & or supra sternal retractions– Intercostal retractions– Negative deflection of manometer needle– Paradoxical breathing movement compared to

the ventilator

Difficulty Triggering

• Possible causes:– Maladjusted sensitivity– Excessive Leak (airway or ventilator circuit)– Plumbing Problems:

• HME saturates

• Water in circuit

• Filter resistance too high

– Auto PEEP

HME Resistance

• HME’s & Filters can become saturated and cause increased resistance

• Roger Smith, RRT, et.al found a 17 cmH2O increase (21-38) in PAP on a pt due to the HME. (2006 Open forum)

• “Clinicians must always be aware that, although not proven by this study, humidity may play a role in HME performance. Airway secretions and/or blood impacted against the HME may very likely cause resultant increases in PAP and are examples of HME’s limitations.”

• When in Doubt, Take It OutRESPIRATORY CARE, Vol 51; Number 11. 2006. P.1313

Ventilatory Support of the Spontaneously breathing patient

• In hospitals, some sub acute care & Long term care facilities, ventilator graphics monitoring is used to help troubleshoot patient-ventilator interaction issues (asynchrony)

• Even in Sub Acute Care and Home Care Environments, Access to a Plus & Play ventilator graphics monitor can be of great benefit!

Plug & play monitors are available

CardioPulmonary Technologies, Inc.

Inspiratory Rise Time (Flow acceleration)

• Adjusts inspiratory rise to pressure to match patient preference

• Available in several ventilators for all pressure breaths (PCV, PSV and spontaneous)

• Sets morphology or shape of pressure waveform

Inspiratory Rise Time

•

P

Time

Patient Ventilator Asynchrony

• Classification for Spontaneous Breathing on the ventilator – Includes CPAP, PSV, (VS, TC/AAC/ATC,

PAV+)– Flow cycled, time limited

Patient Ventilator Asynchrony

• Flow Cycling is plan “A”

• Time Cycling is plan “B”•

Flow

Time

in presence of a leak

Transition threshold

Transition threshold not met

Maximum I time

ESENS Sensitivityaka: Termination sens. (PSV%) or Insp Cycle Off

• Alters the flow termination criteria for spontaneous breaths in Pressure Support Ventilation (PSV)– sets the percentage of peak flow that cycles breath

into exhalation:• set to match the patients breathing pattern• adjust breath transition point due to a leak• may improve synchrony of spontaneous breath transition

(inspiration to expiration phase)• Very useful adjustment when leaks are present

ESENS /PSV% Sensitivity, Insp cycle off

25% (Set) 40% (adjusted)

40% (achieved)

Flow

Time

Time Limiting (PSV T MAX)Adjustable on some vents

E sens 25%

Flow

Time

E sens 50%

Flow

Time

E sens 80%

Flow

Time

In the Presence of a Leak

Flow

Time

Patient Ventilator AsynchronyAutoPEEP (NOT just for hospital patients!)

P = +15

P = +5

Ventilator circuit

ETTLung

Diaphragm

Effort

Triggering with Intrinsic PEEP (autoPEEP)

• In presence of air trapping, patient must overcome autoPEEP + trigger sensitivity threshold to trigger the ventilator

autoPEEP = 15 cmH2O

PEEPSens.

Pressure

Time

PEEP 5 cmH2O

Effort Required to trigger

Suspected AutoPEEP on Assessment?

• Does Patient look over distended?

• Is patient anxious/dyspneic?

• Is the patient attempting breaths that the ventilator does not recognize?

• Check you ventilator settings?

• Disconnect the patient from the ventilator briefly, observe and monitor

Ventilation Needs Specification Comparison

Lowest Vt

Sensitivity Weight

Battery Other features

Achieva 50 cc Flow or Pres 32 lbs 4 hour No bias/ + TS

HT 50 100 cc Pressure 15 lbs 10 hour 7 lpm/ no TS

LTV 950Pulmoneti

c

50 cc Flow 13.4/16.1 lbs

1 hour/4 hours

10 lpm/ + TS

T-Bird Legacy

50 cc Flow 33 lbs 25 min Adj bias/ + TS

•All specification taken from manufacture specification found on web site, literature or operational manual.•Choices of significant specification needs are the opinion of the RC and Medical Team of RJ Ped Hosp and may Differ for other facilities or situations.

Sub-Acute/ Home Ventilation Needs Specification Comparison

E sens Rise Time

Achieva X X

HT 50

LTV 950Pulmoneti

c

X X

T-Bird Legacy

X

Home Care Ventilator WISH List

• Longer battery life

• Dual control breath type

• Proportional Assist Ventilation

Tube Compensation (AAC, ATC, TC)

• Spontaneous Breath type enhancement

• Assists Patient’s spontaneous breath by delivering positive pressure proportional to the inspired flow to overcome the resistance of the artificial airway

Tube Compensation/ Automatic Airway Compensation

• Enter size (ID) of artificial airway• Enter airway length (or Type- ETT or

Trach Tube)• Ventilator measures inspiratory effort (flow) and

proportionally assists the breath to negate the resistance/ work imposed by the artificial airway

• Some vents allow PSV to supplement AAC

Tube Compensation Logic

TC - Support Variability

Pressure

Flow

TC - Support Variability

VS= Volume Constant “Dual Mode” Breath Types - Spontaneous Breaths

• Similar in function to mandatory breath types, except that patient drive controls inspiratory time

• They target either tidal volume (VS) or minute volume (MMV or ASV) preset by the clinician

• Pressure rises or falls to maintain the set volume targets

Example of Changing Respiratory Drive – Large Changes in Tidal Volumes =

Large Pressure Change

Volume Targeted Pressure Control Breath Types

– Volume Control Plus– V Sync– AutoFlow– PRVC

Home Ventilator Wish List

• Goals of Volume targeted/ pressure control breaths (VTPCV)– Improve patient comfort:

• Try to take advantages of benefits of volume & PCV breath types combined

• Flow match patient’s inspiratory flow demands

• Minimize peak airway pressure

• Allow active breathing throughout the inspiratory phase

Volume Control +

• VC+ (PRVC; V sync; Autoflow) – Pressure Control Breath type with Volume Guarantee

• Ventilator initiates test breath (compliance estimated)• delivers next breath at calculated pressure necessary to achieve

target VT• ensuing breaths, pressure is increased or decreased to reach

volume target (most ventilators allow no greater than 3 cmH2O step change per breath)

• Patient determines peak inspiratory flow during each breath (as in PCV)

• Usually available in Assist Control or SIMV modes• Vti vary somewhat breath to breath from target VT• Leaks may cause problems with the ventilator’s logic

Proportional Assist Ventilation

• What is the PAV+?

• A new spontaneous breath type (Tube Compensation (TC) PLUS augmentation/ amplification of the patient’s own respiratory effort

• Enhanced monitoring capabilities

• Enhanced graphic displays

“PAV is the only mode of ventilation designed on a physiological basis where

the technical solutions offered by ventilators did not come first…it allows the patient to attain whatever ventilation

and breathing pattern that best fits the ventilatory control center” –

[N. Ambrosino Thorax. 2002; 57:272-276]

Literature on PAV

How does PAV+ Work?

• A spontaneous breath type (the patient MUST be breathing; apnea back up is active)

• Measures flow and volume every 5 ms• Measures compliance and resistance every 4-10

breaths• Instantaneous measurement of flow is an indicator of

patient’s effort• The measurements of R and C allow the ventilator to

compute the pressure needed in relation to the patient’s breathing effort and the % Support Pressure (Proportional Assist) set by the clinician

PAV+

• The patient is proportionally supported in all conditions, thereby controlling and limiting patient work.

• Support increases as demand increases.

• Under ideal PAV+ conditions, the patient controls all facets of his or her inspiration.

• Indeed, the patient is in control.

PAV+ Conditional Requirements

• Ensure no large leaks (affects R and C measurements) BIG Challenge for Potential Home care Application

• Tube sizes 6.0–10

• Do not use silicone breathing circuits

• Ideal body weight (IBW) at least 25 kg (not for neonates)

Research

• Duke University– Pig study– Compared work of breathing of CPAP and PS

versus PAV

Hypothesis

PAV will require less inspiratory work in spontaneously breathing animals with high respiratory drives as compared to pressure targeted forms of partial ventilatory support.

Ventilator Strategies (settings used in Duke study)

• CPAP +5• PSV 6• PSV 12• PAV 40%• PAV 60%• PAV 80%

• PEEP + 5, FiO2 0.21

Work of Breathing

00.20.40.60.8

11.21.41.61.8

2

0 2.5 5

Inspired CO2

WO

B

CPAP +5

PSV 6

PSV 12

PAV 40%

PAV 60%

PAV 80%

Physiologic Response of Ventilator-dependent Patients with Chronic Obstructive Pulmonary Disease to Proportional

Assist Ventilation and Continuous Positive Airway Pressure

• 8 COPD patients• Average vent time 41+/- 26 days• Compared CPAP vs. PAV• Conclusion: We conclude that in difficult-to-wean COPD

patients, (1) PAV improves ventilation and reduces both P 0.1 and inspiratory muscle effort; (2) the combination of PAV and CPAP can unload the inspiratory muscles to values close to those found in normal subjects.

Am J Respir Crit Care Med 1999;159:1510–7

CardioPulmonary Technologies, Inc.

Summary

• Patient Ventilator Synchrony is very important to support the spontaneously breathing patient

• Stabilize the patient on the Homecare Vent while still in the acute care setting.

• Access to ventilator graphics very useful.• Patient assessment and Application of appropriate

settings (flow sensitivity, rise time, e sens, TC, VS, PAV+) may improve patient comfort & potential outcome

• Know your Ventilator; Know your Patient; Know your graphics monitoring!

2006 WORLD CHAMPION ST LOUIS CARDINALS

THANK YOU!Bill Lamb, BS, RRT, CPFT, RCP

• Bemes Home Medical, Inc

• 810 Sun Park Drive

• Fenton, MO 63026 USA

• 1-800-969-2363 Ext. 122

• blamb@bemes.com