Respiratory Flashcards
Inspiration is:
Active part of ventilation- diaphragm contracts via autonomic nervous system
Respiratory rate and depth of breath is controlled by?
- The Medulla Oblongata and Pons
- Changes in carbon dioxide, hydrogen ion and oxygen levels in the blood
- Autonomic nervous system
- Chemo and stretch receptors
Oxygen dissociation is potentiated by:
- Pyrexia
- Acidosis
- Hypercarbia
- Hypercapnia
Adequate oxygenation requires:
- Ventilation
- Diffusion
- Perfusion
Purpose of surfactant in alveoli
- Reduces surface tension of water
- Increases pulmonary compliance
- Prevents atelectasis at end of expiration
Oxygen debt causes cells to do what?
Metabolise glucose into lactic acid
Aerobic Metabolism turns oxygen and glucose into:
- Heat (Kcal)
- Carbon Dioxide (Co2)
- Water (H20)
- Adenosine triphosphate (ATP)
Serous membrane lining the lungs
Visceral pleura
Ventilation is
Movement of gases between the atmosphere and alveoli
Respiration occurs at three levels :
- Ventilation
- External Respiration
- Internal Respiration
Functions of the Larynx
- Contains epiglottis which protects trachea from aspiration
- Contain the vocal cords
- Forms part of the anatomical deadspace
- Contains cricoid and thyroid
It does NOT filter out particles
Expiration is:
Passive
Involves the relaxation of diaphragm
Involves the recoil of the lungs
Causes of respiratory failure
- Atelectasis
- Pneumonia/infection
- COPD (asthma/chronic bronchitis/emphysema)
- Pulmonary embolism
- Haemothorax/pneumothorax
- Secondary to cardiac failure
- Drugs
- Neurological
Symptoms of Respiratory Failure
- Increases work of breathing=hypoxia=cyansis=silent chest
- Hyperdynamics=shock=poor perfusion=circulatory collapse
- Altered mental state=exhaustion=coma
Chemoreceptors:
- Peripheral in aorta carotid body respond to Pa02
- Peripheral and central (medulla) respond to Co2
Stretch Receptors
In trachea and bronchial smooth muscle- detect over stretch and stimulate expiration (relaxation of diaphragm is active in this case) to reduce chance of overinflation/barotrauma to lungs
VQ ratio Mismatch
V=ventilation
Q= perfusion
- Deadspace- anatomical or disease, eg clot PE or extreme pneumothorax
- Shunt- areas of good perfusion but POOR ventilation eg. pneumonia
Deadspace is:
Areas within respiratory system that are ventilated but not perfused.
Ie. Trachea, bronchi and bronchioles
Respiration is:
Ventilation- active and passive
External Respiration- gas exchange within lungs
Internal Respiration- within tissues at cell level
Lines thoracic wall
Parietal Pleura
Fluid filled space surrounding lungs
Pleural Cavity
Daltons Law
Gases exert pressure against each other- this partial pressure = p
p02+pco2+pN2+pH20=. 101kPa
oxygen 21%
Nitrogen 79%
Gasses diffuse from areas of high to low pressure
Henry’s Law
The amount of gas that will dissolve in liquid is proportional to the partial pressure of the gas and its solubility coefficient- when temperature is constant.
Arterial Blood Gas Interpretation
pH- H+ ions
pCO2- partial pressure of arterial CO2
pO2- the partial pressure of arterial O2
HCO3 sodium bicarb- bicard in plasma
Base Excess- the amount of bicarb needed to return an equilibrium
Control of pH- RESP
Normal pH 7.4
H2O + CO2 —-> H2CO3 (carbonic acid)
Resp= increases RR to blow off acidic CO2
Control of pH- RENAL
In acidosis kidneys eliminate H+ and retain HCO3
In alkalosis kidneys eliminate HCO3 and retain H+
via urine
Control of pH- Buffering systems
Bicarbonate
Haemolglobin/proteins
Inorganic phosphates and other buffers
Buffering
Co2+H2o H2Co3H+ + HC03
Intermediate + natural =compensation
VS
Treatment + medically managed =correction
Partial or Complete compensation
Partial= pH normal but other systems involved
Complete= pH normal and other systems corrected
Type 1 Respiratory Failure
PaO2 <8 with normal or low CO2
Acute hypoxic event- asthma, pneumonia, ARDS
Type 2 Respiratory Failure
PaO2<8 and CO2 >6.1
(ventilation failure)
chronic, chest wall deformities, Respiratory depression
Chemoreceptors and CO2
Co2 diffuses into CSF —> Carbonic Acid
H2CO3
Analysing Gases
HCO3 if low + pH low = metabolic acidosis
HCO3 in high and pH high= metabolic alkalosis
BE- metabolic
PaCO2 and PaCO2- respiratory or pH
Breath Sounds
Vesicular Breath- normal
Bronchial Breath- higher pitch
Added breath sounds- crackles (fine/coarse) or wheeze (mono/polyphonic)
Functional Residual Capacity
Volume left post expiration
PEEP
- Positive end expiratory pressure
- Increases gas exchange (external respiration
- increases functional residual capacity
- Maintains open airways
PRESSURE SUPPORT
-Increases tidal volume
-Increases Co2 removal
-Supports inspiration
start at 5 to 8 above peep
Tidal Volume normal values
6-8ml/kg
Rapid sequence induction
Sedation- Propofol/Medaz
Opiate- Fentanyl
Paralysis- Rocuronium
BP- Metaraminol
Pressure Modes Ventilation
CPAP/PS
SIMV PS/PC
Automode PRVC
Volume Modes Ventilation
SIMV VS/VC
Automode VS/VC
PRVC
Ventilator induced lung injury
Barotrauma (high pressure)
Volutrauma (high volumes)
BOTH CAUSE Pneumothorax
Atelectatrauma (shear stress on alveoli)
Biotrauma (inflammation)- Similar to ARDS
OXYGEN TOXICITY
Caused by free radicals
Effects on CVS with Positive Pressure Ventilation
Increases intra-thoracic pressure
=reduces venous return
Increases pulmonary resistance
=decreases cardiac output
Effects on Renal with Positive Pressure Ventilation
Reduced Cardiac output
=reduced renal perfusion
Increase in sympathetic activity= increased ADH production, Aldosterone and increased H20 and Na reabsorption
AND
Increase in thoracic pressure= reduced ANP production = increased Na reabsorption
Effects on Liver with Positive Pressure Ventilation
Reduced cardiac output= reduced hepatic flow
Increased intra-thoracic pressure = increased hepatic congestion
Effects on CNS with Positive Pressure Ventilation
Increased intra-thoracic pressure= Increased ICP and ICC
Reduced cardiac output= reduced blood flow to brain
Nurses role in reduction of VAP
- Subglottic aspirates
- Oral hygiene
- Tracheal cuff pressure +regulation
- Positioning 30 degree
- PPI/stress ulcer prophylaxis
- Sedation level assessment
Tracheostomy Indications
- Upper airway obstruction
- Surgical procedure
- Respiratory insufficiency
- Neuromuscular Disorders- MND
- Long term ventilation
Vital Capacity
Volume of air you can expel on expiration with max effort
Inspiratory Capacity
Maximum volume that can be inspired
Tidal volume
Amount of air that moves in or out per Respiratory cycle
SPUTUM
- Produced by goblet cells
- Normally cleared by cilia and cough
Cleared using direct percussion/ViBS- not good for trauma patients, bleeds pneumothorax and hernias
Postural drainage- not good for ICP, post meds or cardio instability
NORMAL ABG VALUES
pH 7.35-7.45 PaO2 12-14kPa PaCo2 4.6-5.9 kPA HCO3 22-26mmols/L Base Excess +2/-2
