Invasive Ventilation Knowledge Flashcards
What are the 5 indicators for mechanical ventilation
- Failure to ventilate as characterized by increased arterial Co2 tension
- Failure to oxygenate as characterized by increased O2 tension
- Respiratory muscle fatigue or its potential
- Acute respiratory muscle failure due to a disease process such as ARDS, CCF, Sepsis
- (invasive ventilation) Inability to protect own airway due to trauma, drug overdose, neurological dysfunction or anaesthesia
What is the defining difference between NIV and Invasive ventilation
Non Invasive Venilation:
ventilation support for persons able to spontaneously breath in absence of an ETT
Invasive ventilation:
ventilation support via a ETT
Explain Hypoxia
What are the 4 types
Hypoxia is decreased supply of oxygen to the cells or tissues.
1) Hypoxic hypoxia - decreased PaO2, VQ mismatch is the most common cause
2) Anaemic Hypoxia - decreased or defective Hb or haemotocrit
3) Circulatory or stagnant hypoxia - result of decreased cardiac output or obstruction which limits o2 getting to the tissue
4) histotoxic hypoxia - appropriate amount of o2 reaching the cells but the cells are unable to utilise the o2 effectively
Explain hypoxemia and the indentifying level of measurement
- Hypoxaemia is a decreased level of oxygen in arterial blood
- PaO2 <60mmHg
Explain hypercapnia and the identifying level of measurement
- Hypercapnia is an elevated level of Pco2 in venous blood
- Pco2 >45 - on a VBG
Explain lung compliance + what is the formula
- Lung compliance is the lungs ability to expand with a breath and return to their origional state on exhalation
- LC= change in volume/change in pressure
Explain ventilation
the process of physically moving air in and out of the lungs (breathing)
Explain oxygenation
The process of oxygen being absorbed into the blood
Explain deadspace
The volume of ventilated air that doesn’t participate in gas exchange
Explain IPAP
Inspiratory positive airway pressure - the pressure in the lungs at the end of inspiration.
Explain EPAP/ PEEP
End positive expiratory pressure - the pressure in the lungs at the end of expiration keeping the alveoli open for gas exchange
Explain pressure support + what is the formula
- Pressure support is a preset amount of inspiratory pressure that is delivered when a patients spontaneous effort doesnt meet the desired set targets
- PS= IPAP minus EPAP
Explain tidal volume
The volume of inspired air into a breath
Explain Fio2
fraction of inspired oxygen (Fi02)
the blend of oxygen and air to give the desired oxygen which is inhaled.
Explain I:E ratio
How is it set on the vent
the ratio of inspiration : exhalation for each breath is 1:2.
It is determinded by the set inspiratory time and the resp rate
What complication can occur if the I:E is incorrectly adjusted
Gas trapping resulting in auto peep
Explain Auto-PEEP/ Intrinsic PEEP/ Breath stacking
it occurs when the expiratory time is shorter than the required time for a exhalation breath causing a build up of pressure in the lungs
Explain dyssynchrony
Ventilator dyssynchrony is defined as the inappropriate timing and delivery of a mechanical breath in response to patient effort
Explain VQ ratio
The matching of ventilation and perfusion
V/Q ratio
A correct VQ ratio should ensure the right amount of blood and gas received by the alveoli for efficient gas exchange
What are the 2 goals of ventilation
- Improve oxygenation
- improve perfusion
What settings may be adjusted to improve ventilation
- Respiratory Rate
- Tidal volume
Explain the assessment of poor oxygenation
Signs & symptoms:
Tachypnoea
Tachycardia to bradycardia
ALOC
Confusion/ irritable
Hypertension to hypotension
Cyanosis (late sign)
What settings may be adjusted to improve oxygenation
What other 2 factors should be optimised to improve oxygenation
Adjustable Settings
FiO2
PEEP
I:E ratio
Other factors
1. Optimise cardiac output to enhance delivery of oxygen to the cells
2. Optimising Hb to increase oxygen uptake and binding
