pilbeams ch 5 Flashcards
About 75% of patients receiving invasive PPV are intubated
95% with an oral ET and 5% with a nasal ET. Tracheostomy tubes are used in the remaining 25% of patients receiving invasive PPV.
There are two methods of providing noninvasive positive pressure ventilator support
• Continuous positive airway pressure (CPAP) • Noninvasive positive pressure ventilation (NIV)
, CPAP and NIV are most commonly administered
via a face or nasal mask. Ensuring that the mask fits properly will minimize patient discomfort and help prevent air leaks.
Patients with COPD often have trouble generating the pressure difference between the alveoli and the mouth to begin inspiratory gas flow.
The air trapped in the lungs creates a positive alveolar pressure. If the pressure in the lungs is positive at end exhalation, the pressure must drop below the pressure at the mouth to start gas flow into the lungs for inspiration.
Externally applied CPAP can help overcome the
pressure difference between the mouth and the alveoli when flow limitation is the cause of auto-peep. The patient then does not have to work as hard to drop their alveolar pressure. CPAP can decrease inspiratory work.
NIPPV/CPAP Candidates
Impending respiratory failure OSA COPD patients Neuromuscular weakness Chest wall deformities Cardiogenic pulmonary edema Post extubation difficulties Asthma Post –Op complications Pneumonia * Can reduce the need for mechanical ventilation in 60-75% of these cases
In which of the following situations would NIV be tried?
1 Patient in whom blood pressure is 65/35, heart rate is 150 beats/min, and respiratory frequency is 34 breaths/min
2 Patient who nearly drowned who has copious amounts of white, frothy secretions
3 Patient with chronic obstructive pulmonary disease (COPD) and right lower-lobe pneumonia with respiratory acidosis and increased work of breathing (WOB)
4 A 5-year-old child who has aspirated a piece of chicken and is having trouble breathing
3 Patient with chronic obstructive pulmonary disease (COPD) and right lower-lobe pneumonia with respiratory acidosis and increased work of breathing (WOB)
A high percentage of patients who need mechanical ventilation
require invasive positive pressure ventilation via an artificial airway.
Full ventilatory support (FVS)
Ventilator provides all the energy necessary to maintain effective alveolar ventilation Rates > 8 breaths/min Adequate VT for patient Preset volume or pressure Allows patient to rest and recover
Partial ventilatory support (PVS)
Patient participates in the work of breathing (WOB)
Rates < 6 breaths/min
Avoid if pt has increased WOB
2 types of Targeted control variables
Volume
Pressure
3 types of Timing of breath delivery
Continuous mandatory ventilation (CMV)
Intermittent mandatory ventilation (IMV)
Continuous spontaneous ventilation (CSV)
Mandatory breath
Ventilator controls: timing, tidal volume or inspiratory pressure
Spontaneous breath
Patient controls: the timing and the tidal volume
Volume and/or Pressure is based on patient demand and the patient’s lung characteristics
Assisted breath
Has characteristics of both mandatory and spontaneous
All or part of the breath is generated by the ventilator, which does part of the WOB for the patient
A patient receives a breath that is patient triggered, volume targeted, and time cycled. What type of breath is it?
Assisted
It is a patient controlled machine breath. The Vt is delivered by the ventilator and the ventilator cycles the breath.
Targeting Volume as the Control Variable
Volume is constant, pressure based on patient’s lung characteristics
Advantages
Guarantees a specific volume delivery and volume of expired gas
The goal of volume-controlled ventilation is to maintain a certain PaCO2
Disadvantages
Evident when lung condition worsens
High pressures
Flow and sensitivity settings
Watch for patient-ventilator asynchrony if volume/flow isn’t adequate
Targeting Pressure as the Control Variable
Pressure is set as the independent variable
Volume delivery changes as lung characteristics change, therefore volume delivery must be closely monitored
Considered a lung protective strategy
May be more comfortable for the spontaneously breathing patient
Advantages and Disadvantages of Pressure-Controlled Ventilation
Advantages
Allows a set max pressure
Set pressure reduces the risk of overdistention
Decelerating flow pattern
Disadvantages
Volume delivery varies with the patient’s lung characteristics
Clinicians may be less familiar with pressure-control ventilation
VT and expired volume per minute (VE) decrease when lung characteristics deteriorate
Pressure control ventilation and volume control ventilation are
are equally beneficial in patients who are not spontaneously breathing when a targeted flow pattern is used
. In spontaneously breathing patients,
pressure-controlled ventilation may lower the WOB and improve patient comfort to a greater extent than volume-controlled ventilation, thereby reducing the need for sedatives and neuromuscular blocking agents.
Continuous mandatory ventilation (CMV)
Time- or patient-triggered
Intermittent mechanical ventilation (IMV)
Patient receives a set number of mandatory breaths
Can breath spontaneously breaths between mandatory breaths
Continuous spontaneous ventilation (CSV)
All breaths are spontaneous
Patient-triggered
