Primary Key Lists Flashcards
(20 cards)
What factors affect control of respiratory rate
Central (blood)
PaCO2
PaO2
pH
Lung
J receptors
Stretch receptors
Irritants
Cortical
Emotional and higher centres
Hormonal
Progesterone in pregnancy (mainly TV)
Exercise
Drug factors
Opioids
J receptors = sensory receptors located in the pulmonary interstitium ne
C
Causes of hypoxaemia (low PaO2)
FiO2
V/Q mismatch
Shunt
Hypoventilation (high PaCO2
Diffusion
Causes of hypoxia
Hypoxaemic hypoxia
Anaemic
Stagnant hypoxia
Histotoxic
Mnemonic HASH
Causes of an increased AA gradient
V/Q mismatch
Shunt
Diffusion impairment
Membrane transit time
diffusion limited e.g. exercise with endothelial issues
change from perfusion limited to diffusion limited
Causes of hypercapnoea
Increased CO2 production
MH
Thyroid
Sepsis
Fever
Exercise
Decreased CO2 elimination or decreased alveolar ventilation
- Decreased MV (CNS depression, resp muscle weakness, impaired resp mechanics, ventilator issues, O2 induced hypercapnoea, metabolic alkalosis)
- Inadequate gas flows in maplesons circuits (re-breathing)
- Soda lime not changed (re-breathing)
Causes of decreased MV
CNS depression
Neurological - brainstem, stroke, oedema, bleed
Drugs - opioids, hypnotics, benzos
Resp muscle weakness
LMN - spinal cord injury, peripheral nerve injury
Neuromuscular diseases - MG, GBS, botulism
Electrolytes - hypocalcaemia, hypomagnasaemia, hypophosphataemia
Impaired resp mechanics
Chest wall deformity - flail, kyphoscoliosis, burns, big effusions
Increased dead space - PE, COPD, asthma, interstitial lung disease
Obesity hypoventilation, OSA
Ventilator issues
Inadequate gas delivery
Tube/circuit issues
Other
O2 induced hypercapnoea
Metabolic alkalosis
Causes of venous admixture (shunt)
Physiological
Bronchial veins
Thebesian veins
Pathological
Atelectasis
Consolidation
AV malformations
R-L shunt
Eisenmengers
VQ mismatch
Causes of airways resistance
Laminar
Radius
1. Drugs - histamine, disease (asthma, inflammation, infection, neoplasm(
2. Dynamic airways compression
3. Foreign body
Length
Viscocity
Turbulent
Flow/RR
Density
Radius
Lung volume
ETT
Factors that affect lung compliance
Lung
Volume
- Body size
- Disease - atelectasis, oedema, consolidation, lobectomy and pneumonectomy
- Gravity
- Age
Elastic
- Emphysema
- Disease - fibrosis, oedema, ARDS
Surfactant
- Decrease (IRDS, PE, covid)
Chest wall
Kyphoscoliosis
Ank spond
Diaphragm - supine, pregnancy, obesity, pneumoperitoneum
Dynamic compliance
Increased AWR - bronchoconstriction
Time constants of lung units
Factors that affect FRC
Che
Chest wall
Diaphragm
Burns
Kyphosis
Lung
Emphysema
Pulmonary oedema
ARDS
AWR
Dynamic hyperinflation
PEEP
Factors that affect dead space
Apparatus deadspace
ETT and attachments
Anatomical
Individuals
Age
Size and sex
Alveolar
West zone 1
Hypotension
IPPV
Positional
Supine vs. erect
PE
Factors that affect work of breathing
Elastic
Compliance factors
Lung - surfactant, elastic, lung volume
Chest wall - KP, AS, diaphragm
Non-elastic
Airways resistance - laminary, turbulent, lung vol, ETT
Tissue resistance - friction associated with viscoelastic deformation of pleural/CW/abdo interface
Factors that affect PVR
Lung volume
FRC = lowest PVR
PA pressure
CO, gravity, west zones
Hypoxic pulmonary Vasoconstriction
Metabolic
PaO2, PaCO2, pH
Drugs
GTN
Milirinone
Volatiles
Neural
Alpha 1 increases PVR, B2 decreases PVR
Humoral
Eicosanoid, 5HT, catecholamine
Viscocity
Anaemia
Causes of hypotension
Hypovolaemic
Cardiogenic
Distributive
Obstructive
OR preload, rate, rhythm, contractility, afterload
Determinants of coronary blood flow
CBF = CPP/CVR
CPP = ADP - LVEDP
Coronary Vascular Resistance
Radius
- Neural
- Physical - compression/cycle, HR
- Pathology
- Autoregulation metabolic and myogenic
Pressure gradient
High enough ADP and low LVEDP
Myocardial oxygen demand
Neural factors
Sympathetic and parasympathetic
What factors affect myocardial O2 supply and demand
Supply
O2 delivery
- CBF x O2 content (Hb, sats, PaO2)
Demand
Myocardial work
- Wall tension (PL and AL)
- Contractility
- HR and rhythms
- Type of work (Pressure>Vol)
- Wall thickness
Determinants of ICP
Think of components of Munroe Kellie
Brain
- Resection, steroids
- Mannitol, hypertonic saline
CSF
- Drainage
Blood
- Inc. venous outflow
- Metabolic - pH, PaCO2, PaO2
- Nervous system
How does the kidney establish a concentration gradient
Counter-current multiplier
Counter-current exchanger
Role of urea
ADH
Renal handling of acid
Reabsorption of bicarb
Titratable acid PO4 and organic acid excretion
Ammonium
Factors that affect GFR
Filtration barrier
- Endothelial fenestrations
- Basement membrane
- Podocyte foot processes
Molecule
- Size
- Electrical charge
Starling forces
Balance between hydrostatic and oncotic pressures
