By Barbara Pilgrim - NHS Networks...By Barbara Pilgrim SLE Ltd Updated: March 2010 Slide 2 Graphics Monitoring Using The SLE5000 Monitoring of Pulmonary Graphics is only possible when

SLE Ltd Updated: March 2010

§Slide 1

GRAPHICS MONITORING

ByBarbara Pilgrim


§Slide 2

Graphics Monitoring Using The SLE5000

Monitoring of Pulmonary Graphics is only possible when using aFlow Sensor. The SLE 5000 ventilator makes use of a heated wire sensor, which is lightweight and has a low dead space ofless than 1ml.

Pulmonary Graphics Monitoring has many uses in Neonatal mechanical ventilation.

continually monitor status of the disease and evaluate the ventilationstrategies

identify over-distension, gas trapping and optimum PEEP levels, allowingfor better lung protective strategies.

see the effectiveness of Surfactant

weaning progress of the infant.


§Slide 3

Graphics monitoring information available on the screen

I:E Ratio

Measured TiVte

Minute Volume% Leak

ResistanceCompliance

C20/C

DCO2 in HFO

Loops – Flow/Pressure: Flow/Volume: Volume/Pressure

Waveforms – Pressure, Volume, Flow

24hr trending of all measured parameters


§Slide 4

Terms and Meanings

Tidal VolumeTidal volume is the volume of air inspired with each breath, and is measured as the change in volume between Peak Inspired Pressure and PEEP. Accepted Tidal Volume for a term newborn is 4 – 8ml/kg; preterm infant 4 – 6ml/kg

Minute VolumeMinute Volume is dependant on time i.e. the number of tidal volume breaths taken per minute. Accepted Minute Volume for a term newborn is 200 – 400ml/kg.


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Terms………ET Tube Leakagedifference between measured inspired volume and measured expired volume. Calculated as a percentage.

Pressure, Flow and Volume waveformsPressure waveforms are graphical descriptions of information received from the pressure line relating to PIP, PEEP, MAP,

FrequencyFlow waveforms are derived from information from the flow sensor, relating mainly to inflation pressures, inspiratory and expiratory times, termination sensitivity, triggering and measured volumes. Volume waveforms are derived from Flow and Time information


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Lung MechanicsComplianceThe relationship between a change in volume and a change in pressure.Dynamic Compliance - measurement of compliance based on peak pressure

CD = ___VTI___ PIP – PEEP

Static Compliance - measurement of compliance based on static pressure

CST = ___VTI___PST – PEEP

C20/C - calculated value of the compliance of the last 20% of the compliance loop compared to the entire loop. Over distension will result in the ratio being < 1.


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Lung Mechanics cont……

Resistance - the relationship of pressure to flow.Resistance = Pressure

Flow

Normal Values for Compliance and Resistance for term infantsPulmonary Compliance: 2 – 2.5 ml/cmH2O/kgChest wall compliance: > 4 ml/cmH2OPulmonary resistance: 20 – 40 cmH2O/L/secResistive work: 20 – 30 gm – cm/kg


§Slide 8

Gas Transport Coefficient

In HFO the Pulmonary Gas Exchange is dependant on oscillatory volume. The volume Is dependant on oscillatory frequency and amplitude. Oscillatoryvolume impacts on CO2 elimination. Lower frequencies allow for highervolumes.

Reducing the frequency increases the volume, thereby removing the CO2.This is indicated by an increase in DCO2. An increase in frequency willlower the volume resulting in an increase in CO2. This is indicated by adecrease in DCO2.

The elimination of CO2 in HFO is represented by the equationVT² x f = DCO2


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Loops

Pressure Volume Loops These loops demonstrate the relationship of pressure to volume. May be used to evaluate lung compliance


§Slide 10

Flow Volume Loops

These loops display the relationship between volume and flow.

These loops are useful in evaluating the state of the airways e.g. airway resistance in conditions such as meconium aspiration syndrome and BPD.


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Interpreting what you see

ComplianceA flattened loop indicates poor compliance.

A more upright loop indicates improving compliance.This loop is useful when administering Surfactant to see the improvement after instillation of Surfactant.


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Overdistension

By making use of P-V loops the clinician is able to correct any over distension thereby minimising volutrauma

A ‘beaking’ of the P-V loop is an indication of over distension – pressure continues to rise with little change in volume. Adjusting the PIP will reduce the ‘beaking’.


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Obstructive Airways Disease

Certain conditions in the sick neonate cause increased expiratory resistance due to airway obstruction e.g. Meconium Aspiration Syndrome and BPD.


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Pressure and Flow Waveforms

Pressure waveforms:

A graphical description of what is measured in the pressure line. These waveforms are squarish in appearance. The pressure wave is proportional to the gas flow rate.PIP is the maximum pressure point and PEEP is the baseline pressure level.The area within the pressure curve represents the MAP.


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Inspiratory TimeInspiratory time is measured from the beginning of flow in inspiration to the onset of expiratory flow.

Inspiratory time too shortThe expiratory flow starts before the inspiratory flow reaches the baseline, the lungs may not be optimally expanded. Increasing Ti will achieve better lung expansion and may decrease oxygen requirement.


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Inspiratory time too longIf the inspiratory time is too long i.e. if the expiratory flow commences long after the inspiratory flow reaches the baseline, the lungs will be expanded for longer than necessary. This may cause volutrauma

Expiratory time too shortThe inspiratory flow commences before the expiratory flow reaches the baseline. Due to the shortened expiratory time there may be gas trapping. This may lead to hypercapnia


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Expiratory time too longThe inspiratory flow commences long after the expiratory flow has reached the baseline. Shortening the expiratory time will increase the ventilator rate and MAP. This in turn will increase oxygenation and CO2 clearance.

ResistanceGas trapping is more likely to occur where there is a higher resistance. Higher resistance causes expiratory flow to return to the baseline more slowly than when there is a low resistance.


§Slide 19


Low tidal volume If tidal volumes are below the accepted values, the infant may be under ventilated. The O2 requirements may increase, and the CO2 may be above acceptable limits. The infant may require higher pressures due to stiff lungs or airway obstruction

High tidal volumeThe infant may be over ventilated. Hypocapnia may be present. Infants with significant lung disease may require higher tidal volumes to maintain oxygenation, and acceptable CO2 levelS. Decreasing pressures over inflation may be prevented and oxygenation may be improved by decreasing the intra – pulmonary shunt.


§Slide 20


ET Tube Leakage An ET tube leak can be seen on the volume waveform when the expiratory portion of the waveform does not reach the baseline.

Asynchronous ventilationThe infant may ‘fight’ the ventilator causing variable tidal volume delivery. By changing to SIMV the inter action between patient and ventilator results in a more consistent tidal volume especially if combined with PSV/

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By Barbara Pilgrim - NHS Networks...By Barbara Pilgrim SLE Ltd Updated: March 2010 Slide 2 Graphics Monitoring Using The SLE5000 Monitoring of Pulmonary Graphics is only possible when