Mechanical Ventilation

Linda Winn, RN, MSN Ed.

Terms Tidal Volume – VT

Dead Space– VD

FIO2 PEEP Barotrauma Volutrauma

Types of Airways Endotracheal Tube (ET)

Oral Nasal

Tracheostomy (Trach) Tracheotomy (surgical procedure)

Intubation

Intubation

ET tube - placement verification Analysis?

Tracheostomy

Mechanical Ventilation: General Concepts Not curative

Substitution for bellows action of thoracic cage and diaphragm

Supportive Able to breath independently Bridge to long-term ventilation Decision made to withdraw support

Indications for mechanical vent Inability to maintain safe PaO2 or PaCO2 even

with other oxygenation devices

Can be secondary to: Mechanical failure (ventilation failure)

CNS disorders Chest wall injuries

Impaired Gas Exchange ARF, ARDS Left-sided HF Pulmonary edema PE

Criteria for Mechanical Vent Apnea Impending failure/inability to breath ARF

pH <7.25 and PaCO2 >50

Severe hypoxia Resp. muscle fatigue COPD patients

Special considerations

Types of Mechanical Ventilation Negative Pressure

External – pulls outward – creates negative pressure Ie. Iron Lung Non-invasive - No artificial airway Few problems with secretions / airway management Fewer complications Rare in acute care setting

Positive Pressure Pushes air in, under positive pressure Requires intubation and cuffed tube 2 types:

Pressure controlled / cycled Volume controlled / limited

Negative Pressure Ventilators

Positive Pressure Ventilators

Type - Volume Set volume delivered each breath

Starts at 6-8 ml/kg

Volume delivered regardless of: Lung compliance Lung pressures

Safety Pressure limiting valve

Modes of Volume Ventilation Control (CV) or Controlled Mandatory (CMV)

Set # and volume of breaths No spontaneous breaths

Assist-Control (AC) or Assisted Mandatory (AMV) Inspiration triggered by inspirator effort

Then full volume (preset) delivered Set rate – ensures minimum resp. rate Decreases WOB Pt may breath spont., but may loose drive or strength

Intermittent Mandatory (IMV) or Synchronized Intermittent Mandatory (SIMV)

Pt breaths at own rate and volume Periodically, “mandated” breath delivered (either volume or pressure

set) Ensures set # of adequate breaths per minute

Allows pt to do some WOB SIMV – mandated breaths triggered by pt. inspiratio

Ensures adequate tidal volume

Type - Pressure Inspiration ends when preset pressure in

lungs reached

Volume delivered depends on lung compliance and resistance

Safety factors Volume-based alarms critical

Obstruction, kinking of tubes Monitor exhaled tidal volume

Modes of Pressure Ventilation Pressure Support (PSV)

+ pressure during inspiration Augmens pt spontaneous breaths Pt determines RR and tidal volume Often added to other modes of ventilation ie. SIMV

Not used independently during acute resp failure

Pressure-Controlled Inverse Ratio (PC-IRV) Combines PSV with inverse I:E ratio Gradually expands collapsed alveoli Short “E” prevents alveolar collapse Requires significant sedation Indication: ARDS with refractory hypoxemia even with high

PEEP

IMV Can be set to cycle with either volume or pressure (usually

volume)

Optional Settings / Ventilation Techniques

PEEP Positive End-Expiratory Pressure

CPAP Continuous Positive Airway Pressure

BiPAP Bilevel Positive Airway Pressure Non-invasive

High-Frequency Ventilation (HFV)

Nitric Oxide (NO)

Prone Positioning

PEEP + pressure applied to end of exhalation

Increases FRC Results in + pressure throughout cycle

Increased FRC = More surface area for gas exchange Prevents alveolar collapse / atelectasis Decreases shunts Improved oxygenation Recruits collapsed alveoli

Benefits Adequate PaO2 with lower FIO2 Reduced fluid influx (ie. With Pulm edema) Decreased WOB

Risks Decreased CO

Decreased organ perfusion, incl. renal May stimulate ADH secretion --- decreased UOP

Safety Don’t DC quickly –even for >15 sec Monitor for S/S:

Pneumothorax Decreased CO or venous return

CPAP Similar to PEEP

+ pressure throughout breath Applied to spontaneous breaths

Vent rate set at “0”

Either through mask or ET tube

Often with sleep apnea

Lower pressures than PEEP Less risk of barotrauma

Ventilator Settings Type

Pressure / Volume

Respiratory Rate

Tidal Volume (VT)

Oxygen Concentration (FIO2)

Mode

PEEP

Pressure Support (PS)

Ventilator Settings (Cont.) I:E ratio

Inspiratory Flow Rate

Inspiratory and/or exhalation time

Sensitivity Pts inspiratory effort

Alarm settings High Pressure Limit Low pressure limit Inspiratory and expiratory volumes

Complications of Mech. Ventilation Cardiovascular Pulmonary

Barotrauma Volutrauma

ARDS Alveolar hypo- or hyper- ventilation VAP

F & E Neurological GI Musculoskeletal Psychosocial

Patient Management

Patient Management Assess resp status – Q2h

ABGs, RR, Breath sounds, Pulse Ox

Assess ventilator status ET Tube placement

Secure? Patent?

Settings correct Tubings (kinks, condensation) Humidification

Suctioning needed? Assess at least Q2h In-line suctioning Pre-oxygenate Tube patent

Patient Management - Cont Assess CV status

Arterial BP, HR PA catheter (if inserted)

PCWP, CO, SvO2

Monitor labs

Prevent Infection Atelectasis

S/S?

Prevent VAP Oral care Q1-4h

Sedation, muscle relaxation, pain Propofol Fentanyl Morphine

Patient Management - Cont Monitor Fluid volume status

Precise I/Os, daily weights Nutrition

TPN or enteral only GI

Stress ulcers Guiac stools and gastric drainage

Communication Psychosocial Adequate rest

Patient Management - Cont Positioning

Turn 1-2h Kinetic bed Upright, prone, lateral turns Muscle strength

“Ventilator Bundle” HOB 30-45 degrees Daily “Sedation interruption PUD (ulcer) prevention DVT prophylaxis

Monitor readiness for weaning

Common Meds

Lasix Bronchodilators: Albuterol, Xopenex Inhaled steroids (e.g. pulmocort) SoluMedrol Aminophylline (not so common now…) Norcuron (relative of Pavulon) Morphine and other opioids Heparin, coumadin, lovenox Review meds in shock presentation

Weaning - Indications for readiness Physiologically ready

Underlying problem resolved or greatly improved

Able to ventilate independently (muscle strength) NIP at least -20 Vital capacity 10-15 ml/kg Spontaneous RR < 25 HR <100 Hgb adequate

Hemodynamically stable No Ischemia Adequate BP with no pressors (low dose ok)

Adequate Oxygenation PaO2/FIO2 >150-200 PEEP <5-8 FIO2 <40-50% pH >7.25

Weaning Gradual

Multiple attempts often necessary Gradually increase length of time off vent

Explain procedure

Position Semi or high fowlers

Pre-suction, RT tx

Rested Early morning

Weaning Remove from Vent

Hook up to T-Piece (or IMV/SIMV on vent)

Monitor tolerance of weaning BP change (>20 SBP or >10 DBP) HR increase (>20 or >110) RR increase (>10/min or >35) New cardiac ectopy or increase from baseline PaO2 <60, PaCO2 >55, pH <7.35

May vary for COPD pt

Increase time off vent with each attempt

Extubation Explain / prepare pt

Baseline VS and lung sounds

Equipment ready Mask hooked up to O2 Suction with yankaur Ambu bag Face shield / goggles

Suction ET tube and oropharyngeal airway

Possible RT tx

Semi fowlers position

During and Following Extubation Have pt take deep breath

Immediately after tube removed Instruct pt to cough and exhale forcefully Suction back of airway

Apply O2 Mask

Monitor tolerance RR, Stridor, SOB Changes in sputum

Small amount blood tinged sputum normally initially

Prepare for re-intubation if necessary

Vent Management Web Site http://www.youtube.com/watch?

v=IUZ3Plmz_YQ&feature=related

www.rtconnection.org Click on “students”