Graphics in Neonatal Ventilation notes: ___________________________________________________________________________________________________________ 1

Airway Monitoring 1. Diagnostics and Quantification (RDS, BPD, aspiration syndrom ...) 2. Therapy Decisions (Indication for ventilatory support, surfactant, apnoea therapy ...) 3. Optimizing Ventilator Settings

Airway Monitoring Pressure Flow Volume Lung mechanics

Pressure The driving force for all modes of ventilation commonly used with neonates. Basic monitoring on neonatal ventilators should include Peak pressure Mean airway pressure Positive end expiratory pressure

Pressure Measurement The Pressure Wave Peak Pressure Mean Pressure PEEP Quasi Static Dynamics of pressure Measurements Interaction of ventilator and patient

Problems related to pressure measurement hoses kinking loose connections condensation an extra tube to manage

Pressure Wave

The Babylog 8000 Pressure Measurements Screen

Parameters used to adjust Airway Pressure Pinsp PEEP/CPAP Insp. Flow Standard controls used to adjust airway pressure Can be used to attain: PIP Shape of Pressure Wave I:E ratios Respiratory Rate

Setting Lower Flow Rates Effect on delivered breath Clinical Effect Slower increase in airway pressure Sloping pressure wave form flow into patient is more like a spontaneous breath if Ti not long enough, VT may be impaired, potential  PaC02 Lower MAP thus potential  Pa02 Theorectically less barotrauma

Setting Higher Flow Rates Effect on delivered breath Clinical Effect May help open up atelectatic alveoli and therefore improve gas distribution. May impede venous return Higher MAP thus potential Pa02 Immediate increase in airway pressure PIP reached early in the Ti. Longer time spent at Peak Pressure High initial flow rate into patient. VT delivered early in the Ti.

Five different ways to increase MAP

Changes in Compliance during Pressure Limited Ventilation The ventilator flow rate and the compliance of patient and tubing determine the pressure rise time (slope) of the pressure wave during an inspiratory cycle As a result of change in compliance, the pressure rise time of the pressure wave will change increase in compliance decrease in pressure rise time decrease in compliance increase in pressure rise time notes: ___________________________________________________________________________________________________________ 3

Adjusting flow rate will alter MAP without effecting ventilation

Mean Airway Pressure Trend

PiP and PEEP Measurements The maximum pressure measured during the last completed ventilatory cycle. PEEP or CPAP The baseline pressure. Controls Functional Residual Capacity.

Adjusting Flow Rate Increase flow rate if Decrease flow rate if Pressure rise time is too slow A plateau is desired but pressure does not reach the pressure limit. flow is insufficient to meet spontaneous demand Decrease flow rate if Pressure rise time is too quick A pressure plateau occurs but is but not wanted.

Spontaneous Breaths

Conclusion Pressure waves do provide a lot of information about patient and ventilator interaction. However pressure is only the driving force for flow and volume. Detailed feedback on the patients pulmonary status requires assessment of flow wave forms and volume measurements.

Lung Mechanics "The main benefit of the computerised pulmonary function equipment is for the skilled investigator, who may save considerable time with his study"

Minute Ventilation MV = f * VT

Tidal Volume PEEP PiP D P Ti Vinsp Vt Te trs Rrs Crs

Placement of a Neonatal Flow Sensor Tubing System V . Ct Crs Respiratory System

How the Babylog Detects Flow Direction Hot wire 2 Hot wire 1 Shade exp. Flow Direction insp. Very low flow insp.

Measurement Conditions NTPD versus BTPS Normal Temperature (20°C) Normal Pressure (1013 mbar) Dry Gases (0% rel.humidity) BTPS: Body Temperature (37°C) Body Pressure (ambient pressure + MAP) Saturated Gases (100% rel.humidity) Babylog 8000 BTPS conditions (Conditions at Y-piece): Calibration temperature 25°C Measurement temperature 35°C Relative humidity 90% at 35°C Pressure 1023 mbar p*V = m*R*T 8 9

How do we interpret the Flow Wave ?

Flow Curve during Pressure Limited Ventilation notes: ___________________________________________________________________________________________________________

Timing and the Flow Wave

How can we Recognise Compromise of Inspiratory Flow ?

Flow Curve during insufficient Inspiration Time notes: ___________________________________________________________________________________________________________ Inspiratory time (set on the ventilator) is shorter than the time required for the lung to expand fully. clipping of inspiratory flow occurs

How can we Optimize Ti ?

How can we Detect Compromise of Expiratory Flow and Inadvertent PEEP?

Flow Curve during insufficient Expiration Time notes: ___________________________________________________________________________________________________________ Clipping of expiratory flow occurs when TE is too short relative to the time the lung needs to empty, and this results in incomplete emptying before the next breath is delivered by the ventilator. The latter is termed inadvertent PEEP, (also known as occult, intrinsic, and auto- PEEP).

Flow Curve due to change in Resistance notes: ___________________________________________________________________________________________________________ change in resistance (R) to expiration is indicated by a change in expiratory flow scaling: increase in expiratory resistance prolonged expiratory flow scale decrease in expiratory resistance reduced expiratory flow scale

Effect of Setting Flow Rates on Pressure Waveform Effect of different flow rates on airway pressure profile. (A) Shows a slow increase in airway pressure The absence of a pressure plateau is indicated by a constant flow profile. The preset pressure is not reached. As soon as preset pressure is reached, flow starts to decelerate (B) The increase in flow results in a steeper slope of the pressure curve. A small pressure plateau is visible. Tidal volume is delivered at the end of TI. (C) High initial flowrate results in a faster increase in airway pressure, preset pressure reached earlier in the Ti, a pressure plateau results. Tidal volume is applied within the first half of Ti (inspiratory flow curve reaches baseline), no further gas flow into the patient, lung remains inflated for remainder Ti. notes: ___________________________________________________________________________________________________________ 15 1 5 11 15

Active Expiration active expiration 15 1 4 20 15 The set inspiratory time is set longer as the time needed to fill the lung(Li). This is when active expiration occurs, Babyfights the ventilator, or the machine fights the baby. Active expiration leeds to a reduction in VT and deterioration in blood gas status and predisposed the infants to pneumothoraces. (Remember pneumothoraces are associated with longer periods of active expiration “Study from C. Morley Anne Greenough 1983”). We could avoid this active expiration by adjusting Ti all the time manually. But during weaning process that might change from breath to breath. Therefore we have a new weaning mode which is designed expecially for neonatology. PSV active expiration notes: ___________________________________________________________________________________________________________ 15 1 4 20 15

ET-Tube Leakage via Inspection of Volume Curve notes: ___________________________________________________________________________________________________________

ET-Tube Leakage via Inspection of Volume Curve notes: ___________________________________________________________________________________________________________

ET-Tube Leakage via Inspection of Flow Curve Leakflow notes: ___________________________________________________________________________________________________________

What is the "Normal" VT ?

Tidal Volume oriented Ventilator Management Set Tidalvolume to 5-6 ml/kg Set Ti, so that longer Ti does not increase Vt, shorter Ti does not decrease Vt Set Frequency to maintain desired PaCO2 Set PEEP to adjust oxygenation If oxygenation continuous to be a problem try longer Ti try reversed I:E ratio

PV-Loop of Mechanical Stroke notes: ___________________________________________________________________________________________________________ PV- Loops from mechanical breath strokes move in a counter clockwise direction

PV - Loop during CPAP without PSV notes: ___________________________________________________________________________________________________________ PV - Loops during spontaneous breathing without pressure support move in a clockwise direction.

PV-Loop during Pressure Support Ventilation notes: ___________________________________________________________________________________________________________ According to each breath of the patient during PSV, a different airway volume is reached.

PV-Loop during CPAP with PSV PV-Loops in spontaneous breathing with pressure support result in a small twist in the loop just above zero. The area within this loop represents trigger work of breathing The large right hand loop represents work of the ventilator to deliver a breath. notes: ___________________________________________________________________________________________________________

P-V Loop during PSV using BabyView-Graphics notes: ___________________________________________________________________________________________________________

PV-Loop due to changes in Compliance notes: ___________________________________________________________________________________________________________ Change in compliance results in a transformation of the inspiration loop of the PV-Loop during controlled breathing. increase in compliance slope of inspiratory limb increases decrease in compliance slope of inspiratory limb decreases

PV- Loop due to Lung-Overdistention notes: ___________________________________________________________________________________________________________ Should the upward increment of the inspiration loop become flatter, this may indicate overdistention of the lung. Note: In the presence of a longer pressure plateau, an overdistention can not be detected by PV-Loop inspection!

Visible Lung Overdistention using BabyView-Graphics notes: ___________________________________________________________________________________________________________

Blood Gases Normal Range pH 7.30 - 7.40 pCO2 4.0 - 5.5 kPa pO2 5.5 - 8.0 kPa

Respiratory acidosis in a baby with RDS Example 1 Arterial Blood Gases Settings Volumes pH pCO2 pO2 bic PIP/ MAP rate Ti Te O2 Vt MV PEEP 7.19 8.1 8.7 19 26/5 13 66 .45 .45 66 2.1 .14 Case history: Baby T. 28 weeks gestation, birth weight 0.80kg. Ventilated from birth for hyaline membrane disease, now 48hrs of age. Ventilator Settings Ti : 0.45s Te : 0.45s f : 66/min Peak : 26 mbar Peep : 5 mbar

Respiratory acidosis in a baby with RDS Example1 Aim keep PO2 as it is reduce PCO2 by increasing MV Settings Volumes PIP/PEEP MAP rate Ti Te O2 Vt MV 28/3 13 75 .4 .4 66 3.5 0.63 1.Step Improve VT aim : 5mL/kg Pip ð 28 mbar PEEP ð 3 mbar 2.Step Increase MV by increasing the rate Ti = 0.4 Te = 0.4

Blood gases after 1 hour Example 1 Arterial Blood Gases pH pCO2 pO2 bic 7.32 5.6 8.6 20

Respiratory alkalosis in a baby with BPD following a PDA ligation Example 2 prior surgery Case history: Baby D. Born at 26 weeks gestation, birth weight 0.650kg. Ventilated from birth for RDS, now 29 days old (0.7kg) with BPD. Still ventilator-dependent, despite two courses of steroids. Planned surgical ligation of patent ductus arteriosus. Arterial Blood Gases Settings Volumes pH pCO2 pO2 bic PIP/ MAP rate Ti Te O2 Vt MV PEEP 7.40 4.7 8.8 22 22/3 7.8 35 .5 1.2 35 4.3 .15 Ventilator Settings Ti : 0.5s Te : 0.65s f : 30/min Peak : 27 mbar Mean : 9 mbar Peep : 4 mbar

Respiratory alkalosis in a baby with BPD following a PDA ligation Example 2 after surgery Arterial Blood Gases Settings Volumes pH pCO2 pO2 bic PIP/ MAP rate Ti Te O2 Vt MV PEEP 7.58 2.2 10 16 27/4 9.0 30 .5 0.65 50 6.7 .20

Respiratory alkalosis in a baby with BPD following a PDA ligation Example 2 Arterial Blood Gases pH pCO2 pO2 bic 7.32 5.6 8.6 20 Aim reduce PO2 allow pCO2 to rise arterial blood gases 25 minutes later 1.Step reduce VT aim : 5-6 mL/kg 2.Step reduce rate Settings Volumes PIP/PEEP MAP rate Ti Te O2 Vt MV 20/3 6.5 25 .5 1.9 50 4.1 0.11

Normal arterial blood gases but excessive tidal volume in a preterm baby Example 3 Case history: Baby K, born at 26 weeks gestation weighing 700g. Maternal steroids given during 48hrs prior to delivery. Poor Apgar scores at birth, intubated immediately and ventilated. Now 10 hrs old with good oxygen saturation and CXR looks almost clear. Arterial Blood Gases Settings Volumes pH pCO2 pO2 bic PIP/ MAP rate Ti Te O2 Vt MV PEEP 7.35 5.0 8.0 20 22/3 6.0 23 .5 2.1 35 7.9 .18 Ventilator Settings Ti : 0.5s Te : 2.10s f : 23/min Peak : 22 mbar Peep : 3 mbar FiO2 : 35%

Normal arterial blood gases but excessive tidal volume in a preterm baby Example 3 Settings Volumes PIP/PEEP MAP rate Ti Te O2 Vt MV 15/3 5.7 40 .5 1.0 40 4.5 0.18 Aim reduce Vt maintain MV and normal gas 1.Step reduce VT 2.Step compensate for MV Arterial bloodgas 1 hour later Arterial Blood Gases pH pCO2 pO2 bic 7.39 4.7 8.2 21

mean optimal ventilation! Suggested Guidelines Normal gases may not mean optimal ventilation!