Respiratory Failure & Intubation (Wk1) Flashcards
What 2 things does the respiratory system consist of?
- a ventilatory pump
- a gas exchanging organ
what are the 2 main things of the ventilatory pump?
respiratory muscles and thorax
what organ is the ‘gas exchanging organ’ of the respiratory system?
the lungs
what happens when the ventilatory pump/ gas exchanging organ fail?
respiratory failure
does the pump failing indicate a CO2 movement problem or O2?
CO2
does the lungs failing indicate a CO2 or O2 movement problem?
O2
define respiratory failure
syndrome in which the respiratory system fails in one/ both of its gas exchange functions
what are the gas exchange functions of the respiratory system?
oxygenation & carbon dioxide elimination
4 types of respiratory failure
- hypoxemic
- hypercapnic
- acute
- chronic
Hypoxemia?
less oxygen in the body/ O2 movement problem
What are the PaO2 values in hypoxemic respiratory failure?
<60 mmHg on room air
—-> normal = >80mmHg
PaCO2 levels in hypoxemic RF?
normal/ low
why are the PaCo2 levels normal / low in hypoxemic RF?
if there is less O2 in the body being diffused to tissues and cells, there is less gas exchange occurring and l…
what does hypoxemia mean? (4)
- lung failure
- O2 gas movement issue
- reduced regional ventilation
- lung disease which is severe enough to interfere with O2 exchange e.g. ILD
Signs and symptoms of Acute Hypoxaemia
- dyspnoea
- changes in pattern of breathing (e.g. increase RR)
- agitation followed by drowsiness
- decreased mental acuity (PaO2 <40-50 mmHg)
- organ failure e.g. renal failure, brain injury
What is PaO2?
the partial pressure of oxygen in the arterial blood
is the PaO2 high or low in hypercapnic RF?
low
Is the PaCo2 high or low in hypercapnic RF?
high - > 50 mmHg
(normal = 35-45mmHg)
Hypercapnic RF means…
- pump failure
- primarily a CO2 gas movement issue
- reduced alveolar ventilation (can’t blow off CO2 to get in O2)
- pump = inadequate and cannot maintain ventilation to eliminate the CO2 produced by metabolism
- PaO2 will be low as well, since inadequate fresh gas enters the lungs (CO2 cant be blown off so O2 cant be inspired)
Signs and symptoms of Acute Hypercapnia
- dyspnoea
- Increased RR / change in POB
- agitation, tremor
- confusion –> coma
- increased ICP (CO2 does that), headache
what do the symptoms of hypercapnia depend on?
- rate of rise of CO2
- extent of metabolic compensation
Acute RF
- rapid onset, short course
- pronounced symptoms & can be life threatening
Chronic RF
- long duration of poor ABG values (days –> months)
- will be (metabolic) compensation, therefore pH can be normal
acute on chronic
e.g. acute exacerbation of COPD
Minute Ventilation abbreviation
VE
VE formula
VE = Vt x RR
VE definition
total volume of air moved in / out of the lungs in a minute
Dead space abbreviation
Vd
Dead space types
anatomical dead space, physiologic dead space
Anatomical dead space definition
non gas exchange areas i.e. conducting airways (trachea, bronchi)
Physiologic dead space definition
non gas exchange areas i.e. alveoli which are ventilated but not perfused (collapsed???)
dead space ventilation Abbn
VD
dead space ventilation formula
VD = Vd x RR
dead space ventilation definition
dead space volume over a minute
alveolar ventilation Abbn
VA
alveolar ventilation formula
VA = (Vt-Vd) x RR
OR
VA = VE - VD
alveolar ventilation definition
amount of gas which reaches the alveoli (for exchange) /minute
how does alveolar ventilation (VA) affect the PaCO2 levels?
inversely
how does alveolar ventilation (VA) affect the PaCO2 levels (theory)?
- low VA = high PaCO2 –> less gas exchange across the alveolar membrane so less CO2 blown off
Mechanisms and Causes of Hypoxaemic RF
- reduced gas going to areas with perfusion e.g. low lung volume due to disease
- no gas going to areas with perfusion (acute lobar collapse)
- diffusion impairment of O2 across interstitium into circulation (pulmonary fibrosis)
SOMETHING WRONG WITHIN LUNGS THAT STOPS O2 MOVING ACROSS THE ALV CAP WALL
mechanisms and causes of hypercapnic RF
- depressed drive to breathe (opiate overdose)
- impaired NM function e.g. GBS, cervical spinal cord injury, respiratory muscle dysfunction
- increased respiratory load –> issue with compliance / resistance
what causes increased respiratory load?
- increased airway resistance, e.g. asthma, COPD
- decreased chest wall compliance e.g. kyphoscoliosis, barrel chest
- decreased lung compliance e.g. lung collapse, consolidation
implications of RF for physiotherapy
- watch signs and Sx
- review medical assessment & management
- determine the type of RF
- determine the cause of RF
- choose appropriate interventions
medical management of hypoxaemic RF
- oxygen therapy
- high flow nasal prongs (AIRVO)
- CPAP delivered (non invasive)
- intubation (invasive) & mechanical ventilation
medical management of hypercapnic respiratory failure
requires ventilatory/ pump support (+ oxygenation support/ FiO2)
- non invasive ventilation (external face mask)
OR
- intubation & mech ventilation
intubation process
inserting an endotracheal tube (ET), through the mouth (oro) or nose (naso) into the trachea
what can happen after intubation
patient can be placed on a ventilator to assist with breathing during anesthesia, sedation/ severe illness
reasons for intubation?
- maintain patent upper a/w
- protect lower respiratory tract
- allow (invasive) ventillatory support/ mechanical ventilation
- facilitate airway clearance (suctioning
tracheostomy
artificial a/w inserted surgically / percutaneously through the neck into the trachea (between 2nd & 3rd tracheal rings)
advantage of trach
- bypasses upper a/w so can use mouth to eat etc
- shorter than ETT (decreases dead space and decreases load –> easier to breathe)
- allows reduction in the level of sedation as it is more comfortable
- easier for the patient to communicate
reasons for trach
same as ETI but
- when intubation & ventilation required for a longer period (>10-14 days)
- to facilitate weaning from mechanical ventilation
- tracheomalacia, tracheal stenosis
physio role in a trach?
- education of ward staff on trache management –> suction procedure, humidification
- checking tube patency (open/ unobstructed)
- tube changes
- decannulation (remocal of trach tube)
- decision making re ability to cough and clear secretions before tube removed
