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SPC Adv Modalities
SPC Adv Modalities Unit 1
Question | Answer |
---|---|
Scalars or variables used in vent graphics? | Pressure, flow, & volume graphed over time |
Pressure is measured in? | cmH2O |
Time is measured in? | seconds or minutes |
Flow is measured in? | L/m |
Volume is measured in? | mL or Liters |
Where will you find the Ordinate & the Abscissa? | Y axis & X axis |
When is the rate of change the greatest? | Beginning of the event |
When is the rate of change the smallest? | End of the event |
Time constants are influenced by: | Changes in vent settings (flow, pressure, Vt), total rate, compliance, & resistance |
Short time constant implies: | A fast rate of change |
Long time constant implies: | A slow rate of change |
Benefits of short I-time: | Allows for longer E-time, reduces risk or occurrence of auto-PEEP, promotes venous return |
Disadvantages of short I-time: | Promotes greater flow turbulence, reduces alveolar ventilation, promotes higher peak airway pressures |
Benefits of short E-time: | None |
Disadvantages of short E-time: | May reduce venous return & cardiac output, drop BP, promotes Auto-PEEP |
Benefits of long I-time: | Can improve PaO2, diffusion time is extended |
Disadvantages of long I-time: | Shortens E-time = can reduce venous return, may compromise cardiac output, patient can't exhale sooner |
Benefits of long E-time: | Promotes venous return, reduces Auto-PEEP |
Disadvantages of long E-time: | Odd breathing pattern - pt may want to take a breath sooner but can't |
Factors that influence waveforms: | Compliance, resistance, flowrate, rate (bpm) |
Problems associated w/ reduced compliance: | Atelectasis - collapsed alveoli, Lung collapse - pneumothorax |
Causes for loss of lung compliance: | ARDS, atelectasis, pneumo, fibrosis, pneumonia, P.E., mainstem intubation, pleural effusion, gastric distension, ascites |
Iatrogenic causes of compliance loss: | High PEEP/CPAP settings, high Vt, high pressure, high FiO2 resulting in nitrogen washout |
Acute causes of resistance: | airway secretions, bronchospasm, biting E/T tube, kinked E/T tube, aspiration of foreign body (usually during trauma) |
Chronic causes of resistance: | Airway edema, mucus migration into E/T tube, plugged filters, overly wet HME's |
Benefits of low flow rates: | Lower airway pressures, improved gas distribution, long I-time = improved oxygenation |
Possible problems with low flow rates: | Extended I-time = smaller E-time = possible auto-peep and reduced venous return |