Wk 2 Flashcards
External respiration
Exchange of gases between the alveoli of lungs and pulmonary blood capillaries
Results in conversion of deoxygenated blood from heart to oxygenated blood returning to heart
Affected by altitude
Nit all alveoli are supplied with blood at any one time (referred to as VQ match)
Physiology of external respiration: inhalation
Oxygen Inspiration Alveoli O2 diffuses across Pulmonary capillaries Blood oxygenated Heart left ventricle
Physiology of external respiration: exhalation
Heart right ventricles De oxygenated blood Pulmonary capillaries CO2 diffuses across Alveoli Expiration CO2
Internal reputation
Exchange of O2 and co2 between systemic blood capillaries and tissue cells
Conversion of O2 blood to de02 blood
Reliant upon diffusion gradient
Only around 25% O2 in blood is needed under normal circumstances
Internal respiration flow diagram
Oxygenated blood
Tissue capillaries
Diffuses through interstitial fluid
Tissue cells
Opposite for CO2
Oxygen transport
97% O2 transported bound to hameoglobin
Haem has 4 binding sites
All sites occupied = full saturation
Factors affecting O2 include: temp, harem levels, pH, paO2
Respiratory disorders
COPD
Asthma
Pneumonia
Assessment of breathless patient
Establish ABC
Results in low levels of O2 in blood (hypoxaemia) and thus low levels of O2 in tissues (hypoxia)
Colour
Conscious level
Facial expressions, posture
Look, listen feel: depth rate of breaths, accessory muscles, chest movement and expansion
Air entry: bilateral breath sounds, type of sound,
O2 sats, blood gases
Types of breathing patterns
Tachypnoea: first indication of resp distress, rapid rate of breathing greater than 20bpm
Bradypnoea: slow rate of breathing less than 12 bpm, deterioration in patient, fatigue, hypothermia, CNS depression, drugs such as opiates
Orthopnoea: must stand or sit upright to breathe properly. Asthma, pulmonary oedema, emphysema
Cheyne-stokes: period of apnoea alternate with periods of hyperpnoea, end stage of life
Kussmaul breathing: air hunger, deep rapid breaths due to stimulation of resp centre in brain caused by metabolic acidosis
Work of breathing
Doesn’t demand the bodies energy stores to contribute
Increase resps requires increased energy
Identifying respiratory distress
Increased resp rates
Increase HR
Sweating Use of secondary muscles Exhaustion Cyanosis Flared nostrils Wheeze from bro how constriction
Peripheral vs central cyanosis
Peripheral: inadequate O2ation of circulating blood, extremities appear blue, poor perfusion, tongue and lips pink
Central: systemic shortage of O2, arterial O2 below 85%, at risk of cardiac arrest, cause include pneumonia, acute severe asthma, PE, pulmonary oedema
Arterial blood gases
Info about patients gas carrying ability and their metabolic and resp status Measure pH (7.35-7.45) Base excess BE (-2-2mmol) Bicarbonate HCO3 (22-26mmol) Partial pressure of CO2 (35-45) Partial pressure of O2 (80-100mmHg)
Hypo ventilation
Raised levels of CO2 (PaCO2) in blood cause severe problems due to acidity
Cause: airway obstruction, CNS depressant drugs, peripheral neuromuscular disease, exhaustion
Tx: 100% humidified O2 increase sat over 90%
Provide assisted ventilation
Reverse CNS drug induced depression
Specialist help
VQ mismatch
Some problems affecting the amount of air or blood supply reaching the lungs include: ventilation decrease in relation to blood flow, blood flow reduced compared to ventilation.
Low VQ: shunt perfusion (alveoli perfused but not ventilated) ET tube in mainstream bronchus
High VQ: dead space ventilation (alveoli ventilated but not perfused) cardiac arrest
Frequent patient response is hyperventilation which has knock in effect of increasing WOB and CO2
Normal airway protection
Epiglottis Glottic closure reflex Laryngospasm Cough reflex Apnoea reflex
Simple airway management strategies
Head tilt and chin lift
Jaw thrust
Recovery position or side lying
Oral suction
Airway adjuncts
Oropharyngeal airway:
Nasopharyngeal
Bag-valve-mask ventilation
O2 and Co2 retention in COPD
Two effects in COPD:
Hypoxic pulmonary vasoconstriction - allows blood to bypass hypoxic alveoli and improve gas exchange
Haldane effect - deoxygenated blood binds CO2 to hameoglobin
Want to reduce the risk of oxygen induced hypercapnia
Oxygen delivery systems
Nasal cannula: 2-6L 24-35%
Simple face mask: 5-12L 24-60%
Non rebreather/reservoir mask: 10-15L >60%
Fixed performance mask
Provide sufficient flow of gas to meet the needs of the patients minute ventilation
% of O2 determined by flow rate not by patients resp rate
Venturi mask is example
High flow oxygen
Large volumes of gas not always a high conc
Aim to meet peak inspiration flow
Indications: cardiac or resp arrest, acute resp distress, hypotension, asthma, pulmonary embolism
Monitoring 02 therapy
Colour
RR
Respiratory pattern
Visual verbal and vital signs of respiratory distress
Other consideration when providing o2
Stopping o2 Tx: normal pH, normal blood gases, sats over 94% on RA
Humidification: o2 flow rates greater than 6L, intubation, tracheostomy
Nebulise
Mechanics of breathing
Controlled by resp centre in brain stem. Relies on chemical and neurological input.
Inspiration: moves air into lungs, negative pressure increases lung volume, diaphragm and external intercostals contract,
Expiration: air moves out, positive pressure, passive, elastic recoil, surfactant important
