applied science of sedation Flashcards
What is used in quiet breathing?
The diaphragm
What is used for more forceful breathing?
Intercostal and accessory muscles
What is tidal volume?
The amount of air that moves in or out of the lungs with each breath
450ml for an average person
What is alveolar ventilation?
The amount of fresh air entering the alveoli in each breath
300ml in the average person
How does gas move across alveolar walls and what determines the rate at which this happens?
Diffusion
Determined by partial pressure gradients
What are the different ways in which oxygen is transported?
Attached to haemoglobin (97%)
Dissolved in plasma (3%)
With increased inspired PO2
How is carbon dioxide transported?
Through erythrocytes
Through plasma
What is carbon dioxide transported as?
Dissolved carbon dioxide (10%)
Combined to carbohydrates (20%)
Bicarbonate ions (70%)
What different receptors control breathing?
Cerebral cortex
Central chemoreceptors
Joint and muscle receptors
Lung stretch receptors
Peripheral arterial chemoreceptors
What is hypoxia?
A reduced supply of oxygen
What are the different types of hypoxia?
Anaemia hypoxia
Stagnant (ischaemic) hypoxia
Cytotoxic hypoxia
What is anaemia hypoxia?
When the oxygen carrying ability of the blood decreases
What is stagnant (ischaemic) hypoxia?
Abnormally low blood flow to the lung
What is cytotoxic hypoxia?
When the cells can’t use their oxygen properly
What is cyanosis?
Blue colouration of the skin and mucous membranes due to a high level of de-oxygenated haemoglobin
2 forms - central and peripheral
Describe central cyanosis
Affects the whole body and is evident in oral tissues
Generally due to decreased oxygen delivery to blood
Describe peripheral cyanosis
Due to decreased oxygen delivery to a localised and peripheral part. Of the body
Often due to reduced blood flow to tissues (stagnant hypoxia)
What do the P, QRS and T waves each stand for in an ECG?
P - atrial depolarisation
QRS - ventricular depolarisation
T - ventricular repolarisation
When is coronary blood flow the greatest?
During ventricular diastole
How is blood pressure (BP) calculated?
Cardiac output x total peripheral resistance
COxTPR
How is cardiac output calculated?
Heart rate x stroke volume
HRxSV
Name 2 arterial pulses
Any from:
- external carotid artery
- facial artery
- superficial temporal artery
- radial artery
Name a venous pulse
Jugular venous pulse
What is total peripheral resistance?
The combined resistance of all the systemic blood vessels
Give 4 advantages of the dorsum of the hand for a cannulation site
Access
No nearby arteries
No nearby nerves
No joints
Give 4 disadvantages of the dorsum of the hand as a cannulation site
Small veins
Susceptibility to cold/anxiety
Mobile veins
More painful
Give 3 advantages of the antecubital fossa as a cannulation site
Big, well tethered veins
Less painful
Less venoconstriction
Give 4 disadvantages of the antecubital fossa as a cannulation site
Access
Potential nerve damage
Potential intra-arterial injection
Joint immobilisation
