Zanni CSM 2012 Handout[1] · disorders (ALI/ARDS) causing pulm edema and stiffness in the lungs,...

1/17/2012

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Understanding Mechanical Understanding Mechanical

Ventilation and its Implications for Ventilation and its Implications for

Physical Therapy InterventionPhysical Therapy Intervention

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Jennifer M. Zanni, PT, DScPTClinical Specialist, Johns Hopkins HospitalLecturer, Johns Hopkins University

ObjectivesObjectives

• Identify types of airways and indications

• Identify common modes of ventilation and describe the assistance that each mode provides

• Interpret common alarms associated with mechanical ventilation and indicate actions

• Describe possible complications associated with mechanical ventilation

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ObjectivesObjectives

• Discuss and synthesize common weaning

parameters and methods

• Describe treatment strategies for mobilizing

the patient requiring mechanical ventilation

• Discuss current literature regarding

rehabilitation of patients requiring mechanical

ventilation

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Why is mechanical ventilation Why is mechanical ventilation

requiredrequired??

• One of the most common indications for using mechanical ventilation is to decrease the work of the respiratory musculature and improve arterial oxygenation

• Patients in acute respiratory failure can have 4-6x the normal inspiratory effort

• Careful selection of vent support and settings is crucial and needs to be individualized to each patient

Tobin, MJ. NEJM, Vol. 344, No. 26, June 28, 2001

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requiredrequired??

• In a study of 1638 patients (8 countries) who required mech vent:

– Acute Respiratory Failure (66%)

• ALI/ARDS, heart failure, pneumonia, sepsis, trauma, surgery complications

– Coma (15%)

– Acute on chronic COPD (13%)

– Neuromuscular disorders (5%)

Esteban, A et al. Am J Respir Crit Care Med. 2000;161:1450-8.


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requiredrequired??

• Impending or existing respiratory failure

– Failure to oxygenate

– Failure to Ventilate

– Or combination of the two

• Airway protection

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Failure to VentilateFailure to Ventilate

• Hypercapnic Respiratory Failure

– Caused by disorders of CNS, neuromuscular

systems, chest wall or airways

– Increased PaCO2 > 50 mmHg

– s/s include tachypnea, agitation, cyanosis, and

decreased mental status

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Failure to OxygenateFailure to Oxygenate

• Hypoxic Respiratory Failure• Inadequate exchange of gases at the alveolar level,

as seen in ARDS

• Decreased PaO2 (<50 mmHg)

– Can occur despite normal ventilation

– Occurs at pulm-alveolar interface due to pulm

edema or fibrosis

– Reduced diffusing capacity and V/Q mismatch

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Failure to OxygenateFailure to Oxygenate

A big challenge in mech ventilation are in alveolar-filling

disorders (ALI/ARDS) causing pulm edema and stiffness

in the lungs, making them difficult to ventilate


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Acute Lung InjuryAcute Lung Injury/ Acute / Acute

Respiratory Respiratory Distress SyndromeDistress Syndrome

• Clinical presentation– Acute onset – Bilateral infiltrates– Severe dyspnea and tachypnea– Hypoxemia

• PaO2/FiO2 < 300 (ALI)• PaO2/FiO2 < 200 (ARDS)

• Can be caused by a variety of factors, usually inflammatory in nature– Pulmonary (pneumonia) vs. extra pulmonary

(sepsis)

Fan E et al., JAMA 2005;294:2889-2896.

Respiratory FailureRespiratory Failure

• Patients at risk for alveolar rupture from mech

vent

• Benefits have been shown with using lower

tidal volumes

• May benefit from prone positioning to allow

ventilation to be distributed more evenly

throughout the lungs


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Types of VentilationTypes of Ventilation

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Positive vs. Negative Pressure Positive vs. Negative Pressure

VentilationVentilation

• Negative Pressure

– Mimics more normal chest mechanics with respiration

– Assists with failure of ventilation, but not oxygenation

– “Iron lung

• Positive Pressure

– Most common

– Opposite of “normal” breathing

http://www.ccmtutorials.com/rs/mv/page4.htm Accessed on 12/2/11 13

TThings to consider…hings to consider…

• What type of airway is in place?

• What are the ventilator settings and what do

they all mean?

• What do I do if the vent alarms?

• What to I do if the vent fails?

• How do I plan treatment in conjunction with

vent weaning?

Start with the ABC’s…Start with the ABC’s…

Airway

Airway ManagementAirway Management

• Endotracheal Tube (ETT)

• Can be placed orally (most common) or nasally

• Passes through the vocal cords


• Tracheostomy tube

• Cuff vs Cuffless

• Inserted below the vocal cords

• Used in more long-term airway management


• Airway cuffs:

– Assists with holding the airway in place

– Allows positive pressure ventilation without loss

of tidal volume

– May reduce risk of aspiration of oral and gastric

secretions

– If pt can talk or is losing tidal volume…cuff may

not be fully inflated

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Ventilator SettingsVentilator Settings

• Tidal Volume

• PEEP

• Mode

• Rate

• FiO2

Challenges to Mechanical Challenges to Mechanical

VentilationVentilation

• Tidal volumes too large can over-inflate lungs and cause alveolar damage

• Tidal volumes too small may increase dead space

• The goal is to use vent settings to optimize gas exchange without damaging the lungs

• Unfortunately, there is no evidence to support one ideal mode or setting of mech ventilation

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Mode Mode & Rate & Rate

FiO2FiO2PEEPPEEP

Actual Actual resp rateresp rate

Type of Type of respirationrespiration

PEEPPEEP

• Positive End-Expiratory Pressure– Pressure given in expiratory phase to prevent closure of

the alveoli and allow increased time for O2 exchange

– Used in pts who haven’t responded to treatment and are requiring high amt of FiO2

– PEEP will lower O2 requirements by recruiting more surface areas

– Normal PEEP is approximately –5cmH20. Can be as high as –20cmH20

– Risks include barotrauma, ptx, and decreased cardiac output

Oxygen TherapyOxygen Therapy

• Prolonged exposure to high levels of oxygen

can be toxic to the lungs

• High FiO2 (>.5) can lead to atelectasis

• Balancing act between FiO2 and PEEP

Modes of VentilationModes of Ventilation

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• Controlled Ventilation

– Vent initiates all breaths at a preset rate and

tidal volume

– Vent will block any spontaneous breaths

– Used mainly in the OR for paralyzed and sedated

patients.


• Assist Control (A/C)– Vent provides a preset resp rate, TV, and

inspiratory flow rate

– Will allow a pt to initiate a breath and then vent will deliver a preset tidal volume

– Machine set at a minimum rate so apnea will not occur if the pt does not initiate a breath

– Disadvantages:

• Hyperventilation if pt has increased resp rate (can lead to resp alkalosis)

• Vent dysynchrony, breath-stacking


• Synchronized Intermittent Ventilation (SIMV)

– Similar to A/C, but pts can take own breaths

with their own TV between mechanically

assisted breaths

– Can be used as a primary mode or a weaning

mode

– May lead to a low resp rate in a pt who does not

initiate breaths if rate is set low


• Pressure Support Ventilation (PSV)

– Pt initiates breath & vent delivers a preset

inspiratory pressure to help overcome

airway resistance

– Patient controls the rate, tidal volume, flow

rate and duration of inspiration

– Pts may be more comfortable on PS

– Tidal volume is variable

– Can be used in conjunction with SIMV or

CPAP settings


• Pressure Support Ventilation (PSV)

– Higher amounts of PS needed when lung

compliance is decreased or airway

resistance is high or when the patient can

only make weak inspiratory efforts

– PS 5 (low amount)

– PS 10 or greater (high amount)

– Commonly used as a weaning mode


• Pressure Control (PC)

– Similar to pressure support, but a preset

resp rate is set if the patient is not

spontaneously breathing

– If the pt is spontaneously breathing, this

will function similar to pressure support

– May be used in ALI/ARDS to avoid

barotrauma

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• Continuous Positive Airway Pressure (CPAP)

– Constant positive airway pressure provided

during both inspiration and expiration

– Vent provides O2 and alarms, but no respirations

– Improves gas exchange and oxygenation in pts

able to breathe on their own

– Can also be used non-invasively via a face or

nasal mask for sleep apnea pts

NonNon--Invasive Ventilation (NIV)Invasive Ventilation (NIV)

• Bi-Level Airway pressure (BiPAP)

– Delivered by mask, not through an airway

– Similar to CPAP, but can be set at one pressure for

inhalation and another for exhalation.

– Used in sleep apnea but also has been found to be

useful in some patients with respiratory failure to

avoid intubation

Non-Invasive Ventilation (NIV)

• Allows the patient to be able to speak and eat

• Avoids the risks associated with intubation,

sedation

• No protection against aspiration

• Used in decompensated COPD, CHF, hypoxic

and hypercapnic respiratory failure, DNI

patients

Non-Invasive Ventilation (NIV)

• Some emerging evidence in a few small

studies that in patients with severe COPD,

exercise while on NIV improves 6 MWT, LE

muscle fatigue, and oxidative threshold when

compared to the use of supplemental O2

alone

Borghi-Silva A, et al. Respiratory Care. July 2010(58)7, pp. 885-894.

Toledo A, et al. Clinics (Sao Paulo). 2007; 62(2):113-20

Borghi-Silva A, et al. Respirology. 2009, 14, pp. 537-544

Modes of Ventilation

• High frequency oscillatory ventilation (HFOV)– Sets a mean airway pressure, but minimal

change in tidal volume

– Airway pressure is set so that alveoli remain open and “oscillate”

– Small tidal volumes minimize barotrauma

– Inspiratory and expiratory phase are both active

– Was used primarily in neonates, but now also being used in adults with ARDS/ALI.

– Goal is to wean back to regular mech vent

Modes of Ventilation

• Airway Pressure Release Ventilation(APRV)

– Differs from conventional vent

– Cycles between 2 levels of airway pressures to assist with gas exchange

– Elevation of airway pressures with brief intermittent releases of airway pressure

– Facilitates oxygenation and CO2 clearance

– May be an improved way to treat ALI/ ARDS

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Vent Alarms

• High Pressure Alarm (common alarm to come and go…more serious if it continues to alarm)

– Secretions/ needs to be suctioned

– Pt biting tube/ fighting vent

– Water in tubing

– Bronchospasm

– Pneumothorax

– Decreased compliance (i.e. ARDS)

– Kinked tubing/ malposition of ETT

Vent Alarms

• Low Exhaled Volume/ Circuit Disconnect

Alarm

– Pt pops off vent

– Leak in cuff or tubing connections (if patient

can talk around trach, a leak in the cuff is

probable)

– Extubation

Vent Alarms

• Other Alarms

– Tidal volume (high, low)

– Resp rate (high, low, apnea

– Temperature

– Oxygen supply

– Power

Vent Alarms

• General principles…

– Look at the pt first!!! Then follow tubing to the

vent to search for any disconnections

– If can’t find the problem and the patient is in

distress, disconnect the patient from the vent

and bag with 100% O2 (and call for help)

Complications of Mech Vent

• Asynchrony (“bucking”)

• Auto PEEP

– Pt doesn’t expire full tidal volume and air

become trapped

• Barotrauma

– Damage to alveoli caused by increased

pressure and volume

Complications of Mech VentComplications of Mech Vent

• Hemodynamic compromise

• Nosocomial infection

• Anxiety/ Stress/ Sleep deprivation

• Ulcers/ Gastritis/ Malnutrition

• Muscle deconditioning/ Vent

dependence

• Increased intrathoracic pressure can

cause systemic edema due to decreased

venous return

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Weaning Parameters

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Weaning Parameters

• Weaning is one of the most challenging tasks in the ICU

• Up to 25% of patients will have resp distress requiring re-initiation of mech vent support

• However, a patient’s ability to breathe on their own is often underestimated

• 50% of patients who self-extubate do not require re-intubation

Epstein, SK. Contemporary Crit Care. 7(8), Jan 2010, 1-8

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Weaning Parameters

• No routine application of weaning parameters

– Consider weaning only when evidence of clinical

improvement, adequate oxygenation, stable

hemodynamics, and the patient is able to breathe

spontaneously with appropriate resp mechanics

Epstein, SK. Contemporary Crit Care. 7(8), Jan 2010, 1-8

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Weaning parameters

• Adequate Oxygenation

– PaO2 >60-70 on FiO2 .4 to .5 and PEEP 5-

8cmH20

– PaO2/FiO2 ratio >150-200

• Adequate Ventilation

– PaCO2 35-45mmHg

– PH 7.3 to 7.45

Weaning parameters

• Types of weaning trials

– Pressure Support/ CPAP

– SIMV with Pressure Support

– T-piece trial

– Extubation to NIV

Spontaneous Breathing Trials

• Spontaneous breathing trials (whether single

or multiple trials) led to extubation more

quickly than those receiving Pressure Support

and IMV for weaning purposes in patient who

are mechanically ventilated for > 1 week

Esteban, A et al. (1995, Feb 9). N Engl J Med, 332(6):345-50.

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Weaning Parameters

• Signs of distress during weaning…

– Increased tachypnea (>30)

– Increased heart rate

– Irregular breathing pattern or use of accessory muscles

– Agitation or panic unrelieved by assurance

– Decrease pH to less than 7.25-7.3 with increasing PCO2

Treatment ConsiderationsTreatment Considerations

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Treatment Guidelines

• Patients weaning from mechanical ventilation

– Consider each patient’s case and determine their ability to tolerate both spontaneous breathing trials (SBTs) and rehab sessions

– May be optimal to treat prior to SBT or after they are rested

– Consider mobility and strengthening 1st, then weaning

.

.


• Communication and teamwork are

essential for optimal treatment

coordination.

.


• Consider the need for increased FiO2 or vent

support prior to mobilizing a pt in order to

maximize their pulmonary status. Communicate

with medical team to discuss best settings

• Consider reason for resp failure?

– Failure to oxygenate?

– Failure to ventilate?

– Both?


• Oxyhemoglobin dissociation curve

– Remember that SaO2 below 90% represents

large changes in PaO2

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Ambulating a Patient on

Mechanical Ventilation

• Requires teamwork with the entire medical team

• Most standard ventilators do not run on battery.

Will likely need to use a portable ventilator or a

ambu-bag to ventilate the patient while

mobilizing

Ambulating a Patient on

Mechanical Ventilation

• ETT placement

– Make sure tape is secure prior to moving pt!!!

– Look at cm mark at lip before and after treatment to

assure no movement had occurred

• May want to talk with team if patient has an

FiO2 of .60 or greater and/or if PEEP is -10cm

H2O or greater to ensure medical stability

Steps to mobilizing a patient on Steps to mobilizing a patient on

mechanical ventilationmechanical ventilation

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Literature Highlights Literature Highlights

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Early Mobility in the ICUEarly Mobility in the ICU

•Prospective study of 103 consecutive pts admitted to RICU over 6 mo period

•Criteria for inclusion for early activity:

–MV requirement >4 days

–Neurologic: response to verbal stimuli

–Respiratory: FIO2<0.6, PEEP<10 cm H2O

–Cardiovascular: No orthostatic hypotension or pressors

•Activity goal: ambulate >100 ft before ICU d/c

Bailey P et al. Crit Care Med. 2007, Vol 3(1)


• 40% of all mobility activities were performed with an endotracheal tube in place

• At RICU discharge…

– 64% (23) of patients age 65 or greater ambulating more than 100ft

– 74% (36) of patients less than 65 ambulating more than 100 ft

Bailey P et al. Crit Care Med. 2007, Vol 3(1)

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• Transfer of patients to an ICU which promoted

mobility resulted in almost a 3-fold increase in

ambulation

• This improvement in ambulation was not

explained by improvements in physiology

Thomsen SE et al. (2008). Crit Care Med. 2008. Vol 36(4): 1119-1124.


• RCT with early PT and OT for mechanically ventilated

adults (usual care vs. intensive PT/OT co-treatment.

Both groups got daily sedation interruption)

• Sessions begun with PROM if pt was unresponsive

and progressed as patient tolerated to include

AAROM/AROM, ADLs, and mobility

Schweickert, W.D. et al. (2009, May 30. Lancet. 373(9678), 1874-1882


• Pts in intervention group had…

– Shorter duration of delirium (median 2 vs 4 days)

– More ventilator free days (median 23.5 vs 21.1 days)

– Improved return to independent functional status (59% vs.

35%)

– No difference in LOS

Schweickert, W.D. et al. (2009, May 30. Lancet. 373(9678), 1874-1882.


• Multi-disciplinary QI project to decrease sedation

and increase PT and OT services in a medical ICU

• Changes in sedation practices made from continuous

infusion to a prn basis

• Patients were more alert, less delirious, and had low

pain scores

Needham DM et al. (2010, Apr). Arch Phys Med Rehabil. 91(4):536-42


• Results of QI project:

– Increased numbers of patients receiving PT and OT services and increased numbers of treatment sessions

– Deep sedation was not necessary for patient comfort

– Decreased ICU and hospital length of stay (2.1 and 3.1 days respectively)

Needham DM et al. (2010, Apr). Arch Phys Med Rehabil. 91(4):536-42

Thank you!Thank you!

[email protected]

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Additional References

• Bailey, P.P., Miller, R.R., 3rd, & Clemmer, T.P. (2009, Oct). Culture of early mobility in mechanically ventilated patients. Crit Care Med, 37(10 Suppl):S429-35.

• Clini, E & Ambrosino, N. (2005, Sep). Early physiotherapy in the respiratory intensive care unit. Respiratory Medicine, (9):1096-104.

• Ciesla, N. D. (2004). Physical therapy associated with respiratory failure. In DeTurk, W.E and Cahalin, L.P (Eds.), Cardiovascular and Pulmonary Physical Therapy (pp. 541-587). New York: McGraw-Hill.

• Dean, E. (2008). Mobilizing patients in the ICU: Evidence and principles of practice. Acute Care Prospectives, Vol. 17(1).


• Fessler, H.E. & Hess, D.R. (2007). Respiratory controversies in the critical care setting. Does high-frequency ventilation offer benefits over conventional ventilation in adult patients with acute respiratory distress syndrome? Respiratory Care. 2007. 52, (5), 595-605.

• Frownfelter, D. (1987). Chest Physical Therapy and Pulmonary Rehabilitation. (pp. 729-744). St. Louis: Mosby.

• Frowley PM and Habashi, NM. Airway Pressure Release Ventilation: Theory and Practice. AACN. 2001;Vol 12(2), 234-246.


• Hopkins, R.O., & Spuhler, V.J. (2009, Jul-Sep). Strategies for promoting early activity in critically ill mechanically ventilated patients. ACCN Adv Crit Care, 20(3):277-289.

• Irwin, S and Tecklin, JS. (2004). Cardiopulmonary Physical Therapy: A Guide to Practice, (4th ed.). St Louis: Mosby.

• Perme, C., & Chandraskekar, R.K. (2008). Managing the patient on mechanical ventilation in ICU: Early mobility and walking program. Acute Care Prospectives,Vol17(1).

• Sadowsky, H.S. Monitoring and life support equipment. In E.A. Hillegass and H.S. Sadowsky, Essentials of cardiopulmonary physical therapy. (pp. 509-533). 2001; Philadelphia: Saunders.


• Stawicki, S.P., Goval, M., & Sarani, B. (2009, Jul-Aug). Frequency oscillatory ventilation (HFOV) and airway pressure release ventilation (APRV): a practical guide. J Intensive Care Med, 24(4):215-29. Epub 2009 Jul 17.

• Tobin, MJ. (2001, June 28) Advances in mechanical ventilation. NEJM, 344(26) Yosefy, C., Hay, E., & Ben-Barak, A. (2003). BiPAP ventilation as assistance for patients presenting with respiratory distress in the department of emergency medicine. American Journal of Respiratory

Medicine. 2(4), 343-7.

• Zanni, J.M., & Needham, D.M. (2010, May). Promoting early mobility and rehabilitation in the intensive care unit. PT in Motion, 32-39

Zanni CSM 2012 Handout[1] · disorders (ALI/ARDS) causing pulm edema and stiffness in the lungs,...

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