mechanical ventilation


Flashcards on mechanical ventilation, created by Elizabeth Then on 28/08/2018.
Elizabeth Then
Flashcards by Elizabeth Then, updated more than 1 year ago
Elizabeth Then
Created by Elizabeth Then over 5 years ago

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Question Answer
Cuff two functions: prevent aspiration, seal for IPPV - Does no hold tube in place Volume sufficient to hold a seal (less than 30 mmhg) - cuff isolates lungs from outside of atmosphere forming a closed circuit between pt and ventilator - closed circuit = control
Negative pressure ventilators Iron lungs - intrathoracic pressure
What is a ventilator? a positive pressure ventilator is a device that forces gas into patient lungs creates a pressure gradient higher than normal atmosphere or spontaneous breathing - lungs fill with gas and then respire (take away positive pressure ) gas flows out
Indications for ventilation maintain gas exchange in resp failure control over CO2 elimination reduction of cardiac work in cf prophylaxis prior to resp failure (sepsis)
Ventilation function work of switching between inspiratory and inspiratory modes, their cyling - volume cyling - breath is terminated once a set volume is delivered - pressure cycling - cycles off once a preset pressure has been reached therefore volumes will not be constant - time cycling - delivered breath is terminated once a preset time has been reached
Modes - mouth to mouth/mask - IPPV - mechanical ventilation - IMV intermittent mandatory (volume) ventilation - MMV mandatory minute ventilation - SIMV synchronised IMV (assisted) - SIMV + ps + SIMV + pressure support
modes cont BIPAP HFV - high freq vent HFO - ossicilation hfjv - Jet ventilation PEEP CPAP NPV Apnoeic on
Volume control not used as a standard mode delivers a set volume of gas may require pressure that are not too high pressure to deliver the breath is dependent on compliance and resistance encountered
Pressure control PCV - delivered by a pressure limited time cycled ventilator - Gas is delivered until a set pressure is reached - Reserved for pt with poor resp function - For pts with increased risk of barotrauma
Pressure support - assist mode - Patient initiates breath from ventilator - Ventilator assists with supporting pressure - Pt factors decide the VT - indicated for synchrony, weaning, assistance to overcome tube resistance
MMV - mandatory minute ventilation - Allows spontaneous breathing with automatic adjustments of mandatory ventilation to meet the pts present minimum minute volume requirement. - If pt maintains minute volume settings for VT, no mandatory breaths are delivered
MMV cont - if pt minute volume is insufficient, mandatory delivery of preset tidal volume will occur until minute volume is achieved
Modes at time of connection a mode of ventilation will be chosen
MODES CONT SIMV 600 X 12 PS 20 P5 FIO2 100% SIMV = synchronised intermittent mandatory ventilation ventilator modes are either mandatory - pt will receive a vent, breath spontaneous - pt is initiating the breath and receiving assistance from the ventilator
Tidal volume amount of gas moved in a respiratory cycle, measure in mls normal VT - 5-8ml/kg less than 5 may need for ventilation
PS pressure support, is the level of support ventilator will provide if the patient initiates their own breath normal ranges are 10-20h20
PEEP cont improves potential for gas exchange improves FRC through alveolar recruitment and reducing alveolar collapse improves pa02 by improving V/Q mismatch
PEEP Positive end expiratory pressure, how much pressure remains in the alveoli at the end of expiration, maximises the potential for diffusion normal range: 5-10
FRC functional residual capacity amount of air remaining in the lungs following a normal expiration FRC = 2300mls in normal lung
PEEP cont is atmosphere pressure higher than zero at the end of expiration
Intrinsic PEEP also called autoPEEP, PEEPi - consequence of disease process, eg asthma, gas trapping
Auto - PEEP incomplete expiration has occured, gas has trapped, prior to delivery of next breath
I:E ratio incorrect application of I:E ratio will predispose patient to gas trapping normal I:E 1:2 may be changed in conditions such as asthma to extend expiratory time eg 1:4
Inverse ratio ventilation expiratory time is greater than inspiratory time -induces PEEP - deliberate gas trapping to recruit alveoli - may only be used when other respiratory measures have failed - Barotrauma - significant risk
Extrinsic PEEP - external applied PEEP through a ventilator - closed circuit suction - maintain PEEP throughout suction
FI02 fraction of inspired oxygen the percentage amount of oxygen being delivered to the patient range 21-100%
Determination of FI02 aiming for PAO2 of 60-100mmHG ABG guides FI02 after 15 - 30 mins of higher level eg. 100% IF FI02 cannot maintain oxygenation PEEP is indicated The best FIO2 is the minimum required to provide an adequate PA02
Work of breathing the energy required to take a breath WOB = p x v measure of amount of pressure that must be generated to move a certain volume of gas
Nursing care of ventilated pt correct circuit disconnections provide suction monitor ventilator effects observe complications of ventilation check order against ventilator check ETT length check pilot balloon maintain ABGs, Sao2 maintain adequate nutrition care as for unconscious pt, mouth, eye care, oral suction manage pain neurological obs
Nursing care charting VT - vent and pt RR - vt and pt level of PEEP airway pressure compliance
Airway pressure measure of pressure withint the patients airwar
Complications of mechanical ventilation barotrauma (volutraume) injury to lung as a result of over distenstion of lung tissue, either too much volume or too much pressure ie. alveolar injury - pts at risk - high airway pressure - emphysema, asthma - ARDS - high levels of PEEP
To avoid alveolar injury - use small VTs - monitor alveolar pressure below 35cm H20 - avoid RMB intubation - avoid high functions that have large volumes - monitor for PEEP
Manifestations of barotrauma - pneumothorax - simple pneumothrorax - avoid further large volumes/pressure
Surgical emphysema subcutaneous (surgical) emphysema pnumomediastinum - collection of air in the mediastinum (ie between the lungs) secondary to alveoli rupture - can occur in isolation or together with pneumothorax
Complications alteration in CO - monitor urine output - aspiration, pneumonia, ARDS endotracheal tube - physical pressure, tracheal stenosis
Weaning should begin after intubation requires correction of underlying pathology maintaining muscle strength and nutrition
Assessment for weaning consider - resp function, vent support secretions, drugs, abgs - ph normal FIO2 - less than 5 PEEP - less then 5cm H20 VT - guided by pt
VC vital capacity - is a reflection on the muscle/lung strength normal VC 65-75ml/kg the total amount of air that can be exhaled after maximum inspiration
Non- invasive ventilation CPAP, BIPAP - used to avoid intubation - also has risks of barotrauma
CPAP Continous positive airway pressure - relies on spontaneous effort of the patient - the application of constant pressure, above surrounding atmosphere throughout the respiratory tubing and resp cycle - increased FRC, reduce WOB, reduce atelactesis
Contraindications to CPAP - untreated pneumothorax - hypovolamia - patients with elevated ICP - lung condications such as emphysema, as significnat changes to lung structures may have already occured
BIPAP Bilevel positive airway pressure - delivers CPAP but also ensures senses when an inspiratory effort is being made and delivers a higher pressure during inspiration - has an inspiratory (IPAP) and expiratory pressure (EPAP)
NURSING CARE CPAP/BIPAP ensure you know correct settings set CPAP levels prior to patient connection ensure tight seal obtained with mask - observe for pressure areas - check gastric distenstion, pt swallowing air
other modes - high frequency delivery of high rate, small volume neonatal care - ECMO - extracorporeal membrane oxygenation - blood is circulated outside of body and perfused with oxygen
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