- MECHANICAL VENTILATION (CLINICAL) - Flashcards
Discuss Synchronised Intermittent Mandatory
Ventilation (SIMV)
- pre-set number of breaths to a pre-set TV
- pt can initiate spontaneous breaths
- volume is dependant on pt effort, will not top up breaths
- manditory breaths are synchronised with spontaneous breaths (therefore controls RR and MV)
- less likely to have resp alkalosis
- not filling as much which reduces cardiac comprimise
Discuss assist / control (A/C)
- pt able to trigger spontaneous breaths but manditory breaths are not synchronised
- will top-up breaths to a pre-set volume
- increases RR and MV massively and thus resp alkalosis
- PEEP and FRC increase and thus decrease in CO2
Discuss Controlled Mandatory Ventilation (CMV)
- ventilator doing all the WOB (no spontaneous breaths (pt heavily sedated and paralysed)
- pre-set RR and TV
- lets respiratory muscles rest (can have muscle atrophy when weaned)
Discuss Volume cycling
- constant inspiratory flow that gradually increases in pressure with inspiration
- works up to a pre-set TV and inspiratory time
Discuss Pressure cycling
. - constant inspiratory pressure that gradually increases
- works up to a pre-set inspiratory pressure
Define pressure support (PS), and identify when PS is an appropriate intervention
- breath-by-breath ventilatory support by means of a positive pressure
wave synchronized with the inspiratory effort of the patient, both
patient-initiated and patient-terminated - to a limited pressure
- usually used to weane patients from ventilator
Define positive end expiratory pressure (PEEP), and identify when it is appropriate to use PEEP
- Positive end-expiratory pressure (PEEP) is the pressure in the lungs above atmospheric pressure that exists at the end of expiration. It works to recruit alveoli, reduce WOB and increase FRC
Define Tidal Volume and discuss how it is determined
Volume of gas moving in and out of the lungs during inspiration and expiration
- Normal = 6-8mls/kg
Define Minute volume and discuss how it is determined
Volume of gas inhaled or exhaled
- RR X TV
Define rate/frequency and discuss how it is determined
- Vitals
- Blood gas
- Physiological cause for intubation
- Co-morbid conditions
Define inspiratory flow rate/pattern and discuss how it is determined
- Vitals
- Blood gas
- Physiological cause for intubation
- Co-morbid conditions
Define pressure/flow sensitivity and discuss how it is determined
- Physiological cause for intubation
- Co-morbid conditions
- trouble shooting
Define FiO2 and discuss how it is determined
The concentration of oxygen in the air/gas that a person inhales.
RA: 0.21
NP: 1 - 0.24 2 - 0.28 3 - 0.32 4 - 0.36 5 - 0.40 6 - 0.44
HM:
5-10 - 0.4-0.6
Non-rebreather:
5-10 - 0.4-1.0
Define inspiratory/expiratory ratio and discuss how it is determined
Duration of inspiration : duration of expiration in seconds (usually 1:2)
Discuss the physiological effects of mechanical ventilation
CNS: increased ICP
CVS: impaired cardiac function due to increased ITP, reduced RV preload and afterload
RESP: Resp alkalosis, barotrauma
GIT: Gastric distention
RENAL/HEPATIC: elevation in ADH and aldosterone, reduction in renal funtion and renal blood flow,
Outline the possible complications related mechanical ventilation
Airway:
- Aspiration
- Ventilator-acquired pneumonia (VAP)
Breathing:
- Lung injury (barotrauma)
- Atelectasis (from hypoventilation)
- Hypocapnia and Resp Alkalosis (resulting in hypervent)
- Hypercapnia and resp acidosid (hypoventilation)
Systemic:
- Hyperthermia (from overheated inspired air)
- Decrease CO and BP
- Fluid over load
- Resp muscle weakness and atrophy
- Complications of immobility (e.g. PIs)
- GIT issues (paralytic illeus, stress ulcers, distention)
Discuss the alarm settings for peak inspiratory pressure and how to troubleshoot it
- Normal PIP ~ 10-20cmH2O
- High PIP indicates airway resistance
- Caused by:
- Secretions, coughing, gagging
- Kinked or compressed tubing
- Condensate in tubing
- Increased resistance from pt (bronchospasm)
- ETT displacement
- obstruction of foreign material
- Decreased compliance
- Lung collapse, APO, coughing
Discuss the alarm settings for low minute volume and how to troubleshoot it
- Low MV alarm: 10-15% below average MV Check for cause: - Patient disconnected - Leak in circuit - Cuff Leak - Chest tube leak - Flow sensor malfunctioning - Inappropriately set alarm
Discuss the alarm settings for high minute volume and how to troubleshoot it
- 10-15% above average MV Check for cause - pt demmand increased - Ventilator auto triggering (too sensitive) - External nebuliser - flow sensor malfunctioning - inappropriate alarm settings
Discuss the alarm settings for apnoea and how to troubleshoot it
- ?? 10 sec
- Is it an actual apnoeic episode
- alarm setting inappropriate
- ventilator insensitive to pt effort
- leak
- flow or pressure sensor faulty
Demonstrate the ability to accurately interpret arterial blood gases and make appropriate changes to ventilation to optimize gas exchange
Resp acidosis or high PaCO2:
- increase IPAP/PS
- increase RR
- reduce FiO2 in COPD
- ensure EPAP>4
Low PaO2:
- increase EPAP/PEEP
- Adjust FiO2
- increase inspiratory time (?inverse I:E ratio)
Discuss considerations when ventilating obstructive lung disorders. e.g. Asthma/COAD
Asthma + COPD —-> Obstructive
- Increase expiratiory time
- decrease RR
- fast flow
- no unecessary inspiratory pauses
- decrease tidal volumes if plateau pressure is rising
- Permissive hypercapnia
- Aim for MV approx 6L/min
Discuss considerations when ventilating infective lung disorders e.g. pneumonia
Pneumonia —-> Restrictive
- increase inspiratory time
- look at pts position
- Reduce peak inspiratory pressures
- change to pressure control
- work with PEEP to recruit alveoli
- Permissive hypercapnia
Discuss considerations when ventilating Raised ICP e.g. head injury
- PC-CMV and PEEP can increase ICP (only have if necessary to reduce hypoxaemia)
- cautious of hypoxaemia
- suctioning and coughing can increase ICP , but essential
Discuss considerations when ventilating paediatric patients
- Small diameter airway
- Large tongue
- Relatively large occiput
- Infants are nose breathers
- Ensure correct positioning to open airway
- Trachea more cartilaginous and soft
- Larynx higher and more anterior
- Glotis narrowest part airway
- Huge implications for intubation
