Week 9: Caring for the Patient Requiring Mechanical Ventilation

Mechanical Ventilatory Support

-any means by which a mechanical device is used

to support, assist, or

control respirations

-goals: improve gas exchange, ventilation, decrease work of breathing

Indications for mechanical ventilation:

-inadequate oxygenation

-inadequate ventilation

-inability to protect the airway

Negative pressure ventilation

-Ventilation of the lungs by expanding the rib cage to "pull" air into the lungs

-ex: iron lung, cuirass ventilation

Positive pressure ventilation

-force air into the lungs to provide breathing assistance

-ex: non invasive, invasive positive pressure

Invasive positive pressure ventilation

-volume controlled (VC) or pressure controlled (PC)

-breath controlled by either of these two modes

Volume control

-Inspiration ends when the set TIDAL VOLUME is reached

-pressure is variable

Pressure control

-Inspiration ends with the set PRESSURE is reached

-volume is variable

Airway resistace

-opposition of the

respiratory tract to airflow during inhalation and

exhalation

-higher pressure needed if present

-ex: asthma, COPD, broncospasms, anaphylaxis, secretions, fighting the vent

Stiff lung

-decreased, low lung compliance, cannot be easily distended

-think an exercise ball

Loose lung

-increased, high lung compliance, or low elastic recoil

Pos and Neg of volume ventilation:

pos: known minute ventilation regardless of changes in airway resistance or compliance

neg: higher risk of ventilator induced lung injury due to changes in resistance or pressure

Volutrauma

Damage to the lung by excess volume delivered to one lung over the other

-lower tidal volumes (6 mL/kg IBW)

-avoids over distention by reducing fixed volume

Barotrauma

Injury caused by pressure, from too much pressure in the lungs

-<30 cm H2) limits pressure

-continuous monitoring and adjustment to prevent pressures or during stiff lungs

Pos and Neg of pressure ventilation:

-pos: limits peak pressures, less over distention

-neg: no idea how much volume a patient will recieve

Continuous Mandatory Ventilation (CMV)

-delivers a preset number of fully controlled breaths, regardless of the patient’s effort

-ALL BREATHS MANDATORY

Intermittent Mandatory Ventilation (IMV)

-delivers a set number of

mandatory breaths while allowing the patient to breathe spontaneously

between them

-MANDATORY AND SPONTANEOUS BREATHS

Continuous Spontaneous Ventilation (CSV)

-allows the patient to initiate every breath, with the ventilator providing supportive pressure rather than mandatory breaths

-only used with pressure-controlled ventilation

-ALL BREATHS SPONTANEOUS

Pressure Controlled: Continuous

Mandatory Ventilation (PC-CMV)

-delivers a preset number

of mandatory breaths at a preset inspiratory pressure and inspiratory

time

Pressure Controlled: Intermittent

Mandatory Ventilation (PC-IMV)

-delivers a preset

number of mandatory breaths at a

preset inspiratory pressure and

inspiratory time

-between breaths patient can breathe spontaneously

Continuous Spontaneous Ventilation (PC-CSV)

-patient regulates their own tidal volume and respiratory rate each breath is assisted by a preset inspiratory pressure

-decreases patient's work of breathing

-can be used as a weaning trial to see extubation

Positive End Expiratory Pressure (PEEP)

-the application of positive pressure at the end of exhalation

- the amount of pressure

remaining in the lung at the END of the

expiratory phase

Complications of high levels of PEEP:

-DECREASES CARDIA OUTPUT = DECREASED BP

-increases intracranial pressure

-can cause pneumothorax

High pressure causes:

-tube or vent is kinked

-secretions or water blocking tube

-coughing

-bronchospasms

-fighting the vent

-patient biting down on vent

Low pressure causes:

-vent tubing disconnected

-ET cuff leak

-self extubation

What happens as compliance decreases in volume-controlled ventilation?

Higher peak inspiratory pressures (PIP) leading to

barotrauma

The "high pressure" alarm on the mechanical ventilator starts to go off. Patient is experiencing desaturations of 83%

manual resuscitation with ambu bag and 100% FiO2

-ALWAYS TAKE PT OFF AND BAG if cannot determine reason

Minute ventilation equation:

RR x tidal volume

20 breaths/min x 500 mL = 10 L/min

Nursing considerations for intubation:

-REMOVE DENTURES

-place patient in sniffing position with neck extended

-induction and then paralytic agent

Capnography

-provides feedback about the adequacy of ventilation

-assesses how much CO2

Under inflation of cuff:

-escape of ventilator gases

-aspiration (secretions can pool around cuff)

Over inflation of cuff:

tracheal damage

Closed Inline suction system:

-maintains oxygenation better than the open technique

-decreases exposure to

secretions

-DOES NOT decreased ventilator associated pneumonia

Indications for suctioning

-high pressure alarm sound

-coarse breath sounds

-RR increases

-sustained cough

-sudden drop in SpO2

Nursing considerations for suctioning:

-pre oxygenate w/100% FiO2

-limit suctioning 5-10 sec for infants

-limit suctioning 10-15 sec for adults

-if pt cannot tolerate: STOP and manually hyperventilate

-maintain sterile technique

-do NOT put NS into ET tube

-for thick secretions provide hydration and humidification

Nursing considerations for tracheostomy:

-improves pt comfort, allows oral care, nutrition, communication

-provide enteral nutrition (AVOID BOLUS TUBE FEEDINGS)

-maintain HOB at least 30 degree

-NG tube connected to low, intermittent suction if placed below pylorus

Weaning from mechanical ventilator:

-patients who are intubated for less than 24 hours do not need to undergo a

weaning trial

Spontaneous awakening trials (SAT)

-sedation is temporarily paused to see if the patient can

wake up without severe agitation or pain