- CONCEPTS OF VENTILATION - Flashcards
Discuss the advantages of NIV
- avoids the complications of intubation
- lowers intubation and mortality rates
- less expensive than intubation
- decreases risk of hospital acquired pneumonia
- reduces need for heavy sedation and invasive monitoring
- increased comfort
State the contraindications of NIV
- Apnoea
- Cardiovascular instability
- High risk of aspiration
- Decreased GCS
- Claustrophobia / non compliant
- Secretions/vomiting
- Facial trauma
- Nasopharyngeal abnormalities
- Base of skull fractures
- Raised intracranial pressure (ICP)
- Pneumothorax (pre-ICC)
Discuss the possible adverse effects of NIV
- Barotrauma
- Hypotension
- Altered conscious state
- Aspiration risk
- Gastric distension
- Decreased venous return from cerebral vessels
- Pressure sores
- Dry nose and eye irritation
- Conjunctivitis
- Discomfort
- Claustrophobia
- Poor sleep
Define Positive End Expiratory Pressure (PEEP)
- Positive end-expiratory pressure (PEEP) is the pressure in the lungs above atmospheric pressure that exists at the end of expiration. It works to recruit alveoli and reduce WOB
Define intrapleural pressure
- Also known as ‘Intrathoracic pressure’
- Refers to the pressure within the pleural cavity
Define intrapulmonary pressure
-The pressure within the lungs
Discuss lung compliance
- The relative ease with which the lung distends (opposite to lung elasticity - the ease with which the lung returns to normal after being stretched)
Discuss airway resistance
- A measurement of the frictional forces that must be overcome during breathing. This friction is a result of the anatomical structure of the airway resistance of the lungs and pressure from surrounding organs
Differentiate between the indications for intubation and mechanical ventilation
Intubation:
- support ventilation
- protect the airway
- ensure airway patency
- anaesthesia and surgery
- suctioning
Mechanical Ventilation
- IMPENDING OR EXISTING RESP FAILURE DESPITE MAXIMUM TREATMENT
- Cardiopulmonary arrest
- Trauma (especially head, neck, and chest)
- Cardiovascular impairment (strokes, tumors, infection, emboli, trauma)
- Neurological impairment (drugs, poisons, myasthenia gravis)
- Pulmonary impairment (infections, tumors, pneumothorax, COPD, trauma, pneumonia, poisons)
Discuss the goals of mechanical ventilation
- Treat hypoxemia
- Treat acute respiratory acidosis
- Relief of respiratory distress
- Prevention or reversal of atelectasis
- Resting of ventilatory muscles
- increase O2 delivery to cells
- reduce WOB and O2 demmand
Define FiO2
the concentration of oxygen in the air/gas that a person inhales
Define tidal volumes
Volume of gas moving in and out of the lungs during inspiration and expiration
Define minute volume
Volume of gas inhaled or exhaled
- RR X TV
Define respiratory rate
Amount of breaths per minute
Define inspiratory:expiratory ratio
Duration of inspiration : duration of expiration (usually 1:2)
Define pressure support
.The difference between PIP and PEEP
Define flow rate
The speed/velocity of the gas being delivered (will directly effect inspiratory and expiratory times
Explain sensitivity
Trigger for what is counted as a spontaneous breath
Define peak inspiratory pressure
Maxium pressure being delivered during inhalation
Describe Synchronised Intermittent Mandatory Ventilation (SIMV) and include the rationale and indications for it
- pre-set number of breaths to a pre-set TV
- pt can initiate spontaneous breaths
- volume is dependant on pt effort, will not top up breaths
- manditory breaths are synchronised with spontaneous breaths (therefore controls RR and MV)
- less likely to have resp alkalosis
- not filling as much which reduces cardiac comprimise
Describe Assist/Control Ventilation (AC) and include the rationale and indications for it
. - pt able to trigger spontaneous breaths but manditory breaths are not synchronised
- will top-up breaths to a pre-set volume
- increases RR and MV massively and thus resp alkalosis
- PEEP and FRC increase and thus decrease in CO2
Describe Controlled Mandatory Ventilation (CMV) and include the rationale and indications for it
- ventilator doing all the WOB (no spontaneous breaths (pt heavily sedated and paralysed)
- pre-set RR and TV
- lets respiratory muscles rest (can have muscle atrophy when weaned)
Describe Volume control ventilation (VC) and include the rationale and indications for it
- constant inspiratory flow that gradually increases in pressure with inspiration
- works up to a pre-set TV and inspiratory time
Describe Pressure control ventilation (PC) and include the rationale and indications for it
. - constant inspiratory pressure that gradually increases
- works up to a pre-set inspiratory pressure
Define CPAP
Positive pressure applied to the spontaneously breathing pt during both inspiration and expiration; used for the treatment of OSA and to increase mean airway pressure in critically ill pts who are able to breathe spontaneously
Define BiPAP
Bi-level positive airway pressure uses a flow cycle to change between two different positive airway pressures; inspiratory and expiratory
Discuss the nursing management of a patient on NIV
. - Prepare patient (education + upright positioning)
- Inform NIC
- Check with attending Dr setting of limits (e.g. IPAP/EPAP)
- Check equipment, including suctioning
- Base line observations, ECG, gases
- Response (Monitor GCS, should not be commenced on a patient with ACS*)
- Airway (Monitor for patency, Look for secretions, Check equipment including suction)
- Breathing (Monitor RR / WOB / SpO2 / ABG, Assess speech pattern, Auscultate chest, Position – Fowlers, Repeated focussed respiratory assessment, all ventilator settings + documentation)
- Circulation (HR,BP,Cardiac monitor and ECGs, UO, can drop ITP and reduce venous return)
- Disability (1:1 nurse, monitor GCS, PAC, Temp, Nausea)
- Weaning
List three (3) side effects of PEEP
- splints alveoli
- increases surface area for gas exchange
- right sided heart effects
State three (3) indications for NIV
- Elevated respiratory rate
- Difficulty breathing (dyspnoea)
- Increased WOB & Increased use of accessory muscles (tiring from other O2T)
A 64 year old male presents to your emergency department in severe respiratory distress. The patient has a respiratory rate of 44, SpO2 82% on 10L of O2 via Hudson mask and is agitated with a GCS of 11 E2V4M5. The patient has a past medical history of COPD, and decision has been made to intubate and ventilate. Answer the following questions in relation to this case study:
Discuss the type of respiratory failure is this patient most likely to be in?
Rationalise which mode would you select on the ventilator for this patient?
State the formula used to calculate tidal volume in the mechanically ventilated patient?
The patient’s ABG results are a pH 7.25, PaCO2 60, HCO3 24 and a PaO2 of 180 on FiO2 50%:
Interpret the ABG results
Outline the settings you could change to correct the patient’s pH and PCO2?
Identify the settings you could change if the patient was not maintaining their target PaO2 or SpO2?
The patient’s ventilator is alarming and you cannot immediate problem solve the issue, what is an appropriate immediate intervention?
- Type 1 Respiratory Distress
- SIMV
- 6-8mls/kg
- Increase RR, reduce oxygen
- increase TV, increase FiO2 (cautiously in COPD pt)
- Disconnect the ventilator, BVM the pt and call for help
List three (3) potential causes of a low pressure alarm on the ventilator
- Total or partial disconnection
- Loss of airway (total or partial extubation)
- ET tube cuff leak (pt grunting)
List three (3) potential causes of a high pressure alarm on the ventilator
- Secretions, coughing, gagging
- Kinked or compressed tubing
- Condensate in tubing
- Increased resistance from pt (bronchospasm)
State the indications for NIV
- APO (cardiac)
- Sleep apnoea
- ARDS
- Trauma (flail chest)
- Pneumonia
- Chronic/acute respiratory failure
- Atelectasis
- Pancreatitis
- Carbon monoxide poisoning
- Asthma
Clinical manifestations:
- Elevated respiratory rate
- Difficulty breathing (dyspnoea)
- Increased WOB & Increased use of accessory muscles (tiring from other O2T)
- Decreased SpO2 usually less than 90% on high flow O2
- PaCO2 greater than 45mmHg (ABG/VBG)
- Acidosis (pH <7.35)
Explain the negative physiological effects of PEEP
- Impairs CO2 elimination
- Right sided heart effects (increased intrathoracic pressure, decreased preload and afterload of the RV)
- decrease UO
- increased PVR
- increased ICP
List the indications for PEEP
- ARDS
- Asthma
- COPD
- APO
