Ventilator Graphic Waveforms
-Terminology
-Inflection point
-Inflection point- an abrupt change in direction of a loop graphic
-May be seen on the pressure volume loop and used to identify the best PEEP level (lower inflection point) and the best volume (upper inflection point)
-Terminology
-Square wave (Pg 1)
-Square wave the normal flow pattern for a volume control breath, a constant or set parameter (set VT, or set pressure)
-Terminology
-Sine wave (P1)
the normal flow pattern for a spontaneous breath
-Terminology
-decelerating wave
the normal flow pattern for a pressure control or pressure support breath
-Terminology
-Auto PEEP
-Auto PEEP occurs when there is incomplete exhalation (expiratory time does not return to zero) and air is trapped in the lungs
-caused by insufficient expiratory time -Also known as intrinsic peep, occult peep, dynamic hyperinflation
-Types of Graphic waveforms
-Scalers
-Scalers- Graphic displays of pressure. Volume, and flow over time
-Flow -time -Volume - time -Pressure -Time
-Types of Graphic waveforms
-Loops
-Loops- graphic display of two parameters (pressure and volume or flow and volume) on Horizontal (x) axis and vertical (y) axis
-pressure - volume -Flow - volume -Note: time is not depicted on loops
-basic shapes of waveforms
-Square waveform
-Sine waveform -Ramp (exponential)
Pressure time waveform (page 2.) A.
Baseline pressure
-Beginning at End Expiratory
-Zero, atmospheric
Pressure time waveform (page 2.)
B.
Square wave inspiration flow pattern
-The steeper the slope the greater the inspiratory flow
Pressure time waveform (page 2.)
C.
Ppeak
Pressure time waveform (page 2.)
D.
Plateau pressure
Pressure time waveform (page 2.)
E.
Deflection below baseline indicates a PTs trigger effort
-A breath with no negative deflection is a vent triggered breath
-The greater below the baseline the greater the pts effort required to trigger the vent
Pressure time waveform (page 2.)
Note!!
-Note the area under the entire curve, including any PEEP= average airway pressure PAW
Troubleshooting Pressure Time Waveform (page 3-1)
-auto peep can only be identified when an expiratory hold is employed
-During the hold, baseline pressure line rises to the auto PEEP level (depicting pressure still in alveoli) -If applied PEEP is employed, the expiratory hold baseline will rise to total PEEP (applied PEEP + auto PEEP) -Sufficient hold time must be employed to allow the pressure to reach a plateau -Also must be no patient effort during the hold
Troubleshooting Pressure Time Waveform (page 3-2)
-Increased Airway resistance- increase the difference between PIP and PPlat
-PIP increases while Pplat remains stable -Decreases compliance- increased in PIP and Plat (page 4)
Volume Time Wave form (Page 5)
A.
-A Square wave inspiratory flow pattern
Volume Time Wave form (P5)
B
-B. Inspiratiy Vt
Volume Time Wave form (P5)
C
-C. Exhaled volume returns to baseline
-An exhalation curve that does not return back to baseline may indicate a leak or air trapping
Troubleshooting Volume Time Waveforms (P6)
-Auto PEEP or Airtapping (Breath stacking)
-Also known as dynamic hyperinflation -Does not return back to baseline on exhalation (depicting vo;ume still tra[ping in alveoli) -E time needs to extended increase peak flow
Flow Time Waveform (P7)
A
-A- Peak inspiratory flow (set VI)
Flow Time Waveform (P7)
B
-B Peak expiratory flow
Flow Time Waveform (P7)
-C- Expiratory flow pattern have one basic shape and should return to baseline, indicating a complete exhalation
-Expiratory flow that does not return to baseline proper to the next inspiration indicates inadequate Te, resulting air trapping and auto PeeP
Flow Time Waveform
Page 8
Look over Volume Vs. Pressure
