Download - VENTILATOR GRAPHICS
VENTILATOR GRAPHICSVENTILATOR GRAPHICS
LOOPS AND CURVESLOOPS AND CURVES
dr.r.selvakumardr.r.selvakumar
Some definitions…Some definitions…
•Inspiratory flow time: beginning of flow to Inspiratory flow time: beginning of flow to end of flow during inspirationend of flow during inspiration
•Inspiratory pause time:time in inspiration whereInspiratory pause time:time in inspiration where flow is zeroflow is zero
•Inspiratory phase time: Insp.flow time+insp.pauseInspiratory phase time: Insp.flow time+insp.pause timetime
Expiratory flow time,Exp.pause timeExpiratory flow time,Exp.pause timeExp.phase timeExp.phase time
Inspiratory flow rate: rate at which gas flows Inspiratory flow rate: rate at which gas flows into the pt expressed as volume per unit of timeinto the pt expressed as volume per unit of time
Peak pressure: max. pressure during the Peak pressure: max. pressure during the insp.phase timeinsp.phase time
Plateau pressure: resting pressure during Plateau pressure: resting pressure during the insp.pausethe insp.pause
Some definitions…contdSome definitions…contd
•Resistance: ratio of the change in drivingResistance: ratio of the change in drivingpressure to the change in flow rate.cmH2O/L/secpressure to the change in flow rate.cmH2O/L/sec
•Compliance: ratio of a change in volume to a Compliance: ratio of a change in volume to a change in pressurechange in pressure
Some definitions…contdSome definitions…contd
Exp.phase time
flow pause
Insp phase time flow
pause
Flow 0
hold
volume
0
pressure
0
peak plateau
AIRWAY PRESSURE WAVE FORM
normal
High airway resistance
40
20
peakplateau
Volume cont.ventilation
Press.cont.ventilation
LOOPS:LOOPS:
Dynamic relationship between two variablesDynamic relationship between two variableson a graphon a graph
pressure
VOlUMe
inspiration
exhalation
End inspiration
NORMAL P-V LOOPNORMAL P-V LOOP
FRC
inspiration
exhalation
Flow lpm
TV
NORMAL FLOW-VOLUME LOOPNORMAL FLOW-VOLUME LOOP
+30
CONTROLLED VENTILATIONCONTROLLED VENTILATION
- No ins.pause- No ins.pause
Double convexDouble convexBegins at zero volume and near zero pressureBegins at zero volume and near zero pressureIns. Slope – complianceIns. Slope – complianceEnd of insp- peak press and TV attainedEnd of insp- peak press and TV attained
P-V LOOPP-V LOOP
Peakpressure
TV
300
600
900
volumeNormal P-V loopNormal P-V loop
Normal flow-volume loopNormal flow-volume loop
Smoothly curved,rectangular insp.limbSmoothly curved,rectangular insp.limbUpper triangular exp.portionUpper triangular exp.portionApex – peak exp.flowApex – peak exp.flowSlope of exp.flow- reflects the resistanceSlope of exp.flow- reflects the resistanceAnd recoil pressure of the entire ventilatoryAnd recoil pressure of the entire ventilatory systemsystem
Cont.ventilation with PEEPCont.ventilation with PEEP
P-V loop shifts to the rightP-V loop shifts to the right Begins at the PEEP valueBegins at the PEEP value
volume
pressure
Insp.pause
Controlled ventilation with insp.pauseControlled ventilation with insp.pause
•After peak press. Is reached,there is a pauseAfter peak press. Is reached,there is a pause
•During pause,press. drops to a plateau levelDuring pause,press. drops to a plateau level
•Insp.volume will increase during insp.pauseInsp.volume will increase during insp.pause
SPONTANEOUS RESPIRATIONSPONTANEOUS RESPIRATION
starts at zerostarts at zeroinspiration- airway press is negative.inspiration- airway press is negative.loop moves on to left loop moves on to left End of insp- press. Becomes zeroEnd of insp- press. Becomes zeroExhalation-pree.becomes positive,volume dropsExhalation-pree.becomes positive,volume drops
volume
-10 10 20pressure
exhalaton
inspiration
30 lpm
600 volume
Normal F-V loop-spon.respirationNormal F-V loop-spon.respiration
exhalationinhalation
P-V loop –spon.breathing with PEEPP-V loop –spon.breathing with PEEP
F-V loop- lower flows during insp and expirationF-V loop- lower flows during insp and expiration
Spon.breath900ml
10
pressure
SPON.BREATH DURING CONT.VENTILATIONSPON.BREATH DURING CONT.VENTILATION
Spon.breath during cont.ventilationSpon.breath during cont.ventilation
If it occurs during expiration,the pressure dropsIf it occurs during expiration,the pressure dropsand volume increasesand volume increasesAs the pt exhales,press. increases briefly and As the pt exhales,press. increases briefly and volume dropsvolume drops
F-V Loop-spon.breath in cont.ventilationF-V Loop-spon.breath in cont.ventilation
Breath occurs during inspiration
Sudden increase in ins.flow and volumeSudden increase in ins.flow and volumeAs the breath is exhaled,flow & volume move As the breath is exhaled,flow & volume move towards zerotowards zero
30
600ml
Fighting with ventilatorFighting with ventilator
Inhalation at the beginning of ventilator insp.Inhalation at the beginning of ventilator insp.So loop moves to the left of the vertical axisSo loop moves to the left of the vertical axismarked decrease in compliancemarked decrease in compliance
OPEN LOOPOPEN LOOP
900ml
pressure
30 lpm
Open F-V loopOpen F-V loop
OPEN LOOPOPEN LOOP
A loop should return to its starting pointA loop should return to its starting pointGap between the end and starting pointsGap between the end and starting pointsExhaled volume is less than inhaled volumeExhaled volume is less than inhaled volume
Causes:Causes:uncuffed ETT,LMA,leakuncuffed ETT,LMA,leakPartial disconnectionPartial disconnectiontension pnemothoraxtension pnemothoraxextreme absorption of N2Oextreme absorption of N2O
30 lpm
600 ml
An open F-V loopAn open F-V loop
There is still exp.flow when the There is still exp.flow when the next insp. Is commencednext insp. Is commenced
COPDCOPD
OVERSHOOT LOOPOVERSHOOT LOOP
exhaled volume is more than the inspired volumeexhaled volume is more than the inspired volume
P-V loop in decreased complianceP-V loop in decreased compliance
Normal loop
Loop shiftedTo right and down
PEEP may restore the curve back towards leftPEEP may restore the curve back towards left
60 lpmF-V loop- decreased complianceF-V loop- decreased compliance
Flow will be increased during exhalation with a higher peak and steeper slope
500 ml
10 30
pressure
P-V loop – increased resistanceP-V loop – increased resistance
CHANGES IN RESISTANCE:CHANGES IN RESISTANCE:
Higher insp.pressure required to Higher insp.pressure required to deliver the given flowdeliver the given flow TV reducedTV reduced Curve shifted right and downCurve shifted right and down Large internal areaLarge internal area Loop may be open if air trappingLoop may be open if air trapping
P-V loop in emphysemaP-V loop in emphysema
No problem in inflating lungsNo problem in inflating lungsExhalation - press.drops with little Exhalation - press.drops with little change in volume until the end of exhalationchange in volume until the end of exhalationOpen loopOpen loop
F-V loop in emphysemaF-V loop in emphysema
Insp. Almost normalInsp. Almost normalSevere reduction in exp.flowSevere reduction in exp.flowLoop may be openLoop may be open
30 lpm
Fixed tracheal obsBoth are restricted
Extra thoracic obsIns.plateauNormal expiratoryflow
F-V LOOPS IN OBSTRUCTIVE PATHOLOGYF-V LOOPS IN OBSTRUCTIVE PATHOLOGY
airway collapse during exhalationairway collapse during exhalationNormal ins. flowNormal ins. flow
Intra thoracic obstructionIntra thoracic obstruction
RESTRICTIVE LUNG DISEASERESTRICTIVE LUNG DISEASE
increase in elastic recoil increase in elastic recoil associated with high exp.flow and associated with high exp.flow and deep descending flow deep descending flow As disease progresses, lung volume decreases As disease progresses, lung volume decreases And the loop becomes tall and narrowAnd the loop becomes tall and narrow
60 lpm
RESTRICTIVE DISEASERESTRICTIVE DISEASE
normal
One lung intubationDLT deeply placed
BALL VALVE OBSTRUCTIONBALL VALVE OBSTRUCTION
BALL VALVE OBSTRUCTIONBALL VALVE OBSTRUCTION
Tip of the tube impinging on the side wall of tracheaTip of the tube impinging on the side wall of tracheaPress. Rises rapidly with little increase in volumePress. Rises rapidly with little increase in volumeUntil press is sufficient to overcome the obstruction.Until press is sufficient to overcome the obstruction.The vol. Increases and press.drops.The vol. Increases and press.drops.If the press. drops low enough, there will beIf the press. drops low enough, there will beagain an obstruction to flow,creating anotheragain an obstruction to flow,creating anothernotch on the upswing of the loopnotch on the upswing of the loop