Mechanical Ventilation

What is mechanical ventilation?

machine that performs auto cycling to generate air pressure and assist or take over breathing

Who requires mechanical ventilation?

acute respiratory failure (ARDS), HF, PNA, sepsis, trauma, surgery complication, coma, COPD, neuromuscular (SCI, ALS)

Why mechanical ventilation?

airway protection (aspiration), reduce excessive work of breathing (COPD, asthma), depressed respiratory drive (drug OD), failure to: ventilate (correct high CO2) and/ or oxygenate (correct low O2)

How is mechanical ventilation set up and what are the different types?

intubation is the insertion of a cannula or tube into a hollow organ, such as trachea, to maintain opening or passageway; oropharyngeal, nasopharyngeal, endotracheal, tracheostomy

T/F Mechanical ventilation assists with inhalation and exhalation.

false. It only pushes air in the lungs; exhalation is passive

T/F Mechanical ventilation performs gas exchange.

false; respirator or ECMO performs gas exchange

When is an oropharyngeal or nasopharyngeal vent used?

quick/ emergent, short- term ventiation; not long term

Describe an ET tube.

goes in the mouth and down past the vocal cords, balloon inflated on end to keep it in place

How do you know if the balloon is inflated on the ET tube?

the blue balloon outside is inflated

Describe a tracheostomy.

tube can be made of metal, plastic, or silicone; tube may be fenestrated, cuffed, or uncuffed; the cuff is a soft balloon around the distal part of the tube that can be inflated for patients in respiratory failure on the vent

What are complications with tracheostomy?

airway obstruction (secretions, over inflated cuffs, kinking), tracheobronchitis, crusting (from inadequate humidification), hypoxemia, pulmonary edema, infection, stenosis, aspiration, dislodgement

What are complications of mechanical ventilation?

barotrauma/ pneumothorax, oxygen toxicity, diaphragm atrophy (disuse), tracheal malacia/ stenosis, hypotension, loss of mobility, sleep disturbances, loss of speech (damage to vocal cords), psychosis/ depression (long term stay in ICU)

Why is oxygen toxicity a complication of mechanical ventilation? What are s/s?

100% FiO2 over 12 hours allows O2 to quickly diffuse out of the alveoli; may cause congestion, atelectasis, or pulmonary edema; s/s: SOB, burning in the throat and chest, painful breathing

Why is tracheal malacia/ stenosis a complication of mechanical ventilation?

high cuff pressures

Why is hypotension a complication of mechanical ventilation?

with + pressure, increases intrathoracic pressure therefore squeezing IVC—> decreases venous return and cardiac output

What are examples of negative pressure MV?

iron lung and cuirass vest

What are examples of positive pressure MV?

pressure support v volume support, BiPAP, CPAP

How does negative pressure MV work?

Think: pulls ribs out; draws air in; our bodies act as negative pressure ventilators; diaphragm goes down, opens up lungs, causes negative pressure inside forcing air to go into lung

How does positive pressure MV work?

Think: pushes air in; takes high pressure air, forces it into the airways, blowing lungs open from inside out

T/F An individual on MV can also be hooked up to oxygen.

true

What is the general timeline for ET, trach, and oro/ naso MV?

oro/ naso= hours

ET= weeks

trach= months, maybe longer

The diaphragm can atrophy as quickly as _____ hours of being on a MV.

3

T/F Altering settings on the MV are within PT scope of practice.

False; if you are concerned, call the nurse or RT

What is the difference between volume support and pressure support?

volume- put air in based on volume; pressure- inflate to a specific pressure

What are other settings on the MV that can be controlled by the RT?

rate (fast v slow, breaths/ min), flow (give volume slowly v quickly, how much pressure to leave in after breath given and how much pressure), trigger (patient v ventilator), amount of oxygen is added, time (24hrs a day? total time), frequency (# of breaths over time)

What are the modes of ventilation?

spontaneous, assist control (AC), intermittent mandatory ventilation (IMV), synchronized intermittent mandatory ventilation (SIMV), mandatory minute ventilation (MMV)

What is the most common mode of ventilation?

Assist control (AC): patient trigger, MV delivers volume or pressure for inhale/ exhale

What are 2 less invasive modes of ventilation?

continuous positive airway pressure (CPAP) and bi- phasic positive airway pressure (BiPAP)

What is PEEP?

positive end expiratory pressure; pressure given in end- expiratory phase to prevent closure of the alveoli and increased time for O2 exchange

When is PEEP used?

used in those who have yet to respond to treatment and are requiring high amount of FiO2

What is normal PEEP?

PEEP will lower O2 requirements by recruiting more SA; normal PEEP is 3-5cmH2); can be as high as 15 cmH20 in MV patients

What are indications for PEEP?

severe acute lung disease; airways tend to close down/ collapse… hard to reopen

What are benefits of PEEP?

gas exchange, stabilizes alveolar units, lung compliance improves, prevents collapse

What 2 things keep the lungs open?

PEEP and surfactant

What does a higher PEEP mean?

more support needed

What values should we document from the MV settings?

PEEP, mode, FiO2 (O2)

What is bi- level airway pressure (BiPAP)?

noninvasive, nasal mask or face mask; delivers positive pressure at two different levels (inspiration and expiration)

What is continuous positive airway pressure (CPAP)?

maintains constant positive pressure in airways during inhalation and exhalation to prevent atelectasis and promote gas exchange; FiO2 is provided; usually last mode prior to extubation

What are indications for CPAP?

patient is breathing spontaneously, sleep apnea and acute pulmonary edema

T/F PEEP is functionally the same as CPAP.

true

Which CPAP or BiPAP should you confirm that the patient is safe to disconnect for PT?

BiPAP- because sometimes used for respiratory acidosis

When can a patient start weaning off MV?

when the patient demonstrates clinical improvement, adequate oxygenation, stable hemodynamics, and the patient is able to breathe spontaneously and appropriately; adequate oxygenation (PaO2 >60-70) and adequate ventilation (PaCO2 35-45)

What is the method of weaning someone off MV?

alternate periods of breathing with periods of rest; one hour on, one hour off and progress over longer periods of time; use of CPAP or PSV when patient is in control of their rate

When is oxygen weaned?

until the patient is able to tolerate room air

What happens once a patient is weaned off the MV?

ET tube is removed but trach may remain in, may downsize trach during O2 weaning, trial of passy- muir valve/ speaking valve with ST

What is a Passy- Muir Vavle (PMV)?

one way valve allows air in but not out so that air must move past the vocal cords; increases pressure, difficult for patient initially

The cuff should be inflated/ deflated prior to placing PMV on.

DEFLATED

T/F Patient is often unable to generate effective cough with artificial airways.

True- deep suctioning more effective

What is a cap trial?

cap placed over trach to mimic absence of trach; if patient tolerates, trach is removed

How long does it take trach site to heal?

3-5 d

What are PT implications for MV patients?

patients with ET tube will not be able to speak and patients with trach will only be able to speak with passy muir valve, watch for bleeding and/ or secretions around the trach, be mindful of inflated v deflated cuff, patients will have a trach mask that supplies either oxygen or humidified room air (always report O2 from trach mask in FiO2%, venturi mask is modified to provide portable oxygen for mobility)

What are MV alarms?

High pressure (secretions, ventilator tubing, bronchospasm, breath holding/ asynchrony), low pressure (disconnected tubing, leak in tubing; do not use valsalva maneuver), turning patient may cause kinking, disconnection, increased secretions

What are PT treatment considerations while patient is on the vent?

hemodynamically stable with PEEP of 10 or less, positioning, be aware of lines during treatment session, ambulating patient on portable vent or with Ambu- bag (need assist from nursing and/ or RT)

When should you terminate a session?

MV: FiO2>=0.60, PEEP>=10, patient- ventilator asynchrony, MV mode change to AC, tenuous airway, respiratory rate: <5 breaths/ minute; >40 breaths/ minute

What are criteria for HR terminating PT session?

>70% APMHR, >20% decrease in resting HR, <40 bpm or >130 bpm, new onset dysrhythmia, new anti- arrhythmia med, new MI by ECG or cardiac enzymes

What are criteria for BP terminating PT session?

SBP> 180mmHg, >20% decrease in SBP/ DBP, orthostatic hypotension, MAP <65mmHg or >110mmHg, presences of vasopressor med, new vasopressor or escalating dose of vasopressor med

What are criteria for RR terminating PT session?

<5 breaths/ minute or >40 breaths/ minute

What are criteria for pulse ox (SpO2) terminating PT session?

>4% decrease or <88-90%

What are criteria for MV terminating PT session?

FiO2>= 0.60, PEEP>=10, patient- ventilator asynchrony, MV mode change to AC, tenuous airway

What are criteria for alertness/ agitation terminating PT session?

patient sedation or coma (RASS >=-3), patient agitation requiring addition or escalation of sedative med, RASS >2, patient c/o intolerable DOE, patient refusal

What should you include in your PT eval?

breath sounds, observe chest wall expansion, observe spontaneous respirations (are they fighting the vent? are they using diaphragmatic breathing?), ROM, strength, mobility, Document: PEEP, Vent settings, FiO2, SpO2

What are UCSF’s 5 steps for working in the ICU?

1) untangling 2) bed exercise 3) sitting EOB 5) walking

What is extracorporeal membrane oxygenation (ECMO)?

a machine that performs the function of oxygenation

What are indications for ECMO?

peds: pulm HTN, meconium aspiration, respiratory distress, congenital diaphragmatic hernia

adults: cardiac: after heart transplant or other advanced cardiac surgeries, with severe HF, during CPR, pulmonary: after lung transplant, severe respiratory distress or trauma

How does ECMO work?

blood is removed and cycled through a CO2 scrubber and membrane oxygenator returning it to the body with a desired PaCO2 and PaO2

What is the difference between veno- venous (vv) and veno- arterial (va) ECMO? Which supports cardiac output?

vv- takes blood from the venous system and returns blood oxygenated to the venous system- single or double lumen cath

va- takes from the venous side and delivers to the arterial side- supports CO

What are implications for ECMO?

patients can be on ECMO for days to wks; prevent injury from high MV pressures, high fraction of inspired oxygen, and vasopressor meds; full systemic heparinization is required because of platelet activation in the circuit leading to bleeding complications; can works with these patients if carotid cannulation; perfusionist always present