Respiratory Flashcards
What is type 1 respiratory failure
Involves hypoxaemia <60mmHg with normocapnia PaCO2 35-45mmHG
Example: APO
What are the causes of a type 1 respiratory failure
V/Q mismatch; the volume of air flowing in and out is not matched with the flow of blood to the lung tissue
COPD, APO, pneumonia
What is type 2 respiratory failure
Involves hypoxaemia PaO2 <60mmHg with hypercapnia >45mmHg. Occurs as a result of alveolar hypo ventilation which prevents the patient from being able to adequately oxygenate and eliminate CO2 from their blood
What is shunting
Hypoxaemia caused by inadequate ventilation of well perfumed areas of the lung. Occurs in atelectasis, in asthma as a result of bronchoconstriction, pulmonary oedema, and pneumonia when alveoli are filled with fluid.
What are the most common causes of V/Q mismatch
Asthma, COPD, Fibrosis, Pneumonia, pulmonary HTN, PE
Shunt
When blood is transported through the lungs without taking part in gas exchange
What is anatomical dead space?
The air in the “conducting zone” of the airways that don’t participate in gaseous exchange.
What are the clinical manifestations of hypoxia
Confusion, anxiety, tachycardia, tachypnoeic, diaphoretic, restlessness, cyanosis
Define hypercapnia
Increased CO2 in arterial blood caused by hypo ventilation
Clinical manifestations of hypercapnia
Respiratory acidosis - electrolyte abnormalities occur in response to a low pH that can cause arrhythmias.
Sleepy ,Drowsy, Coma - due to changes in intracranial pressure associated with high levels of arterial carbon dioxide which causes cerebral vasodilation
Causes of respiratory failure type 2
Increased resistance as a result of airway obstruction (COPD)
Reduced compliance of lung tissue/chest wall ( pneumonia, rib fractures, obesity)
Reduced strength of the respiratory muscles (guillian-barre, MND)
Drugs acting on the respiratory centre reducing overall ventilation (opiates)
Indications for NIV
Respiratory failure type 2
Gives a push behind each breath and creates positive pressure
COPD with respiratory acidosis pH<7.35
Pneumonia
Hypercapnic respiratory failure secondary to chest wall deformity or neuromuscular
Weaning off tracheal intubation
Indications for CPAP
Respiratory failure type 1
Creates positive pressure in the lungs- preventing alveoli from collapsing.
Hypoxia in the context of chest wall trauma
Cardiogenic pulmonary oedema
Pneumonia: as an interim measure before invasive
Congestive heart failure
Obstructive sleep apnoea
* increases gas exchange by recruitment of alveoli
Contraindications for CPAP/BiPAP
Vomiting/ excess excretions Confusion/agitated Altered conscious state Bowel obstruction Facia burns/trauma Recent facial trauma Inability to protect own airway Pneumothorax (untrained)
Oxygen toxicity symptoms
Nausea, vomiting Anxiety Visual changes Hallucinations Dry cough Substernal chest pain Sob Pulmonary oedema Vertigo Hiccups Seizures
HiFlow
Delivers high flow o2 - respiratory support
Bridge between low flow and NIV (CPAP/BiPAP) and intubation
Able to deliver PEEP 4-8cmH2O
Indications for hiflow in children
Hypoxaemia with respiratory distress due to bronchiolitis and pneumonia, chronic lung disease, congenital heart disease and post extubation
Contraindications of HiFlow in children
Critically ill- requiring higher level of O2 support Upper airway obstruction Central apnoea Asthma Blocked nasal passages Nasopharynx trauma Pneumothorax
HiFlow flow rate in children
2L/kg/min up to 12kg plus 0.5L/kg/min for each kg there after to a max on 50LPM
FiO2 - titrate for SaO2 94-98%
>90% in bronchiolitis
Indications for high flow in adults
Respiratory distress not responding to regular O2 therapy
Includes: COPD, pneumonia, asthma, APO and acute lung injury
Contraindications of HiFlow in adults
Co2 >48 mmHg on ABG
Facial trauma (mid maxillary)
Suspected pneumothorax
Flow rate HiFlow in adults
Commence at 49-60LPM
FiO2 - titrated to maintain SaO2 >90%
NIV - BiPAP
Gives an inspiratory push (pressure support) behind each breath + PEEP
Increases tidal volumes and decreases CO2
Type 2 respiratory failure
SIMV
Synchronised intermittent mandatory ventilation:
Pre-set number of breaths of a pre-set volume/pressure; pt triggers spontaneous breaths which are variable
Physiological effects of NIV
Reduction of WOB Stabilisation chest wall in trauma/surgery Improves oxygenation Decreases after load Reduces V/Q mismatch
Indications for BiPAP
Tachypnoea >24 SOB (mod to severe) Increased WOB accessory muscles/pursed lipped breathing Hypoxaemia (SpO2 usually less than 90% or PaO2 <200mmHg on high flow FiO2) Hypercapnic respiratory acidosis (<7.35, PaCO2 > 45mmHg Heart failure/APO ARDs Trauma (flail chest) Pneumonia Chronic/acute respiratory failure Atelectasis Pancreatitis Carbon monoxide poisoning Asthma?
Nursing assessment of a pt commencing NIV
Response- monitor GCS A- monitor patency, look for secretions B- monitor RR/WOB/SpO2/ABG/VBG Ensure circuit is humidified Assess speech pattern, talking in sentences/words/nil Auscultation chest Repeated focused respiratory assessment NIPPV delivery device
Titration and adjustments on BiPap
Increase iPaP(ps) by 2cmH2O is persistent hypercapnia
Increase IPAP and EPAP 2cmH20 if persistent hypoxaemia- every 10mmol or as clinically tolerated until desired response
Max iPAP should not exceed 20-25cmH2O
Max EPAP should not exceed 10-15cm H20
Aim for the lowest pressure and FiO2 - maintain SaO2 90% or PaO2 60mmHg with out further Clincal deterioration
