Author Of 7 Presentations
ACCURACY OF ESTIMATED ENERGY LOAD DURING PAEDIATRIC MECHANICAL VENTILATION: A BENCH STUDY
Abstract
Background
A simplified equation for quantification of mechanical energy per breath at the bed side has been proposed in adults, but it is unclear if it is also applicable in a paediatric context.
Objectives
To compare the correlation between the calculated energy per breath (ELUNG_C) normalised to body weight between the simplified equation of motion versus the integral of the area of the dynamic pressure-volume loop (ELUNG_M).
Methods
Using a paediatric lung model with different compliance and resistance settings, we compared the energy delivered to the lungs (ELUNG_M) by measuring the integral of the dynamic pressure-volume area with the energy computed by the simplified equation of motion ELUNG_C = ΔV • (Ppeak_LUNG - ½DP) • 0.098 (mJoules) (ELUNG_C : elastic energy for lung inflation, ΔV variation of tidal volume, Ppeak_LUNG peak pressure in the lung, DP driving pressure). Measurements were made during Pressure (PC) and Volume (VC) controlled ventilation with PEEP 5cmH20. Endotracheal tube sizes from 3.0 to 8.0mm were studied.
Results
ELUNG_M was constantly overestimated for a mean of 2.9mJ/kg (mean 5.9±6.3 vs 8.8±6.2 mJ/kg, p<0.05). Bland-Altman analyses showed that computed and measured mechanical energy were significantly different when PC mode was used (beta -0.49 p<0.001) and compliance was above 0.6ml/cmH20/kg (beta -0.49 p<0.001). Large ETT sizes showed better accuracy than small (beta 0.01 p=0.11 vs beta -0.03, p=0.002, respectively).
Conclusion
The adult simplified motion of equation is not applicable in the paediatric context. Further clinical studies are needed to verify whether automated calculation of mechanical energy could be applied in mechanically ventilated children.
THE EFFECT OF SPONTANEOUS BREATHING ON END-EXPIRATORY LUNG VOLUME AND TIDAL VOLUME DISTRIBUTION IN MECHANICALLY VENTILATED CHILDREN
Abstract
Background
Weaning children from the ventilator can be performed by gradual reduction of ventilator support or by attempted with alternating periods of complete ventilatory support and graded spontaneous breathing with assistance, also called sprinting.
Objectives
To study the effect of spontaneous breathing on end-expiratory lung volumes (EELV) and center of ventilation (CoV).
Methods
Prospective study in spontaneously breathing, ventilated children aged <5 years who are ventilated >24 hours. CoV and EELV was measured by electrical impedance tomography (EIT). Sixteen electrodes were applied circumferentially around the paediatric chest and measurements were made at a scan rate of 13 Hz for 60 seconds. Patients were studied during pressure regulated ventilation (pressure A/C) or pressure support (PS) ventilation. Secondary, patients were switched to CPAP/PS and PS was reduced up to 6cm H2O in steps of 2cm H2O.
Results
22 patients were studied. Median age was 6.4 months (IQR 2.4 – 14.2). No differences in CoV were found when between CPAP/PS (median 49.9%, IQR 45.4 - 51.9) and pressure A/C (49.3%, IQR 45.7 – 51.8), whereas a value <50% indicated that the CoV was located in the anterior half. EELV increased when patients were breathing spontaneously (∆Z -6.63 (IQR -9.75 - -4.69) compared to conventional ventilation ((∆Z -7.46 (IQR -11.37 - -6.22)). Reducing PS shifted the CoV to more the more dependent lung regions, although not statistically significant and clinical relevant. No differences in EELV were found when PS was downgraded.
Conclusion
Spontaneous breathing during weaning from mechanical ventilation did not affect EELV or CoV.
Presentation files
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PPT Salzburg ESPNIC 2019_EITpptx 19.06.2019 12:03
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PPT Salzburg ESPNIC 2019_EIT_1906pptx 19.06.2019 14:33
ESOPHAGEAL PRESSURE MONITORING IN MECHANICALLY VENTILATED CHILDREN WITH AND WITHOUT LUNG INJURY
Abstract
Background
In adult populations, esophageal pressure monitoring is increasingly proving its potential to guide mechanical ventilation. In the paediatric population, the data is limited.
Objectives
To observe and objectify esophageal pressure (Pes) in relationship to illness, biometric data and airway pressure (Paw).
Methods
In mechanically ventilated children, an air-filled balloon catheter is placed in the esophagus. After appropriately positioning, ventilator and esophageal pressures during zero-flow state end-inspiration and end-expiration were recorded. For statistical analysis, the relation between Pes and age, and between Pes and Paw was studied by linear regression analysis. Transpulmonary pressures of patients with and without lung injury and patients with normal and decreased chestwall compliance were compared using unpaired testing.
Results
Fifty-two children (median age of 6.5 months) were studied. N = 41 patients (78.8%) were ventilated for lung injury and 7 patients (13.5%) had a decreased chestwall compliance. Both end-inspiratory and end-expiratory, Pes was not related to age (regression coefficient P values of 0.868 and 0.790, resp.). Only in patients with lung injury, Pes was significantly related to Paw both at end-inspiration and end-expiration (regression coefficient P values 0.038 and 0.002, resp.). In both patients with decreased and normal chestwall compliance, Pes was significantly related to Paw at end-inspiration (regression coefficient P values 0.026 and 0.006, resp.). Transpulmonary plateau pressures are significantly lower in patients with a decreased chestwall compliance compared to patients with a normal chestwall compliance (p=0.038).
Conclusion
Bedside esophageal pressure monitoring is applicable in paediatric clinical setting, though its value remains uncertain due to lack of reference values.
OPTIMAL FILLING VOLUME OF THE OESOPHAGEAL PRESSURE CATHETER IN MECHANICALLY VENTILATED CHILDREN: A PILOT STUDY
Abstract
Background
Oesophageal pressure (Poes) manometry allows assessment of respiratory mechanics, enabling individualized titration of respiratory support. Poes can be measured by specifically designed catheters, equipped with a small inflatable balloon. In adults, it has been recommended to perform an individual calibration procedure by creating a pressure volume loop of the balloon to determine the optimal filling volume. We sought to explore if this would also hold true for paediatric patients.
Objectives
To identify optimal balloon filling volume in mechanically ventilated children.
Methods
Mechanically ventilated sedated and/or paralyzed paediatric patients (<18years) with an oesophageal catheter (6Fr paediatric or 8Fr adult size) in situ were included. The oesophageal balloon was inflated incrementally by steps of 0.2mL, respectively with a maximum of 1.6mL and 2.6mL. Respiratory holds were performed at the end of each step. Pressure-volume loops were obtained to identify the minimal, maximal and optimal filling volume. The minimal and maximal filling volume were derived, visually, from the pressure-volume loops. The optimal filling volume was defined as the volume where the highest dPoes, between inspiratory and expiratory phase, was obtained within the range of the minimal and maximal filling volume.
Results
Thirty patients were eligible of whom 15 were excluded because of a confirmed malposition or a suspected malposition of the oesophageal catheter. Of the remaining 15 patients, median age 2 months [IQR 1, 25], optimal balloon volumes were obtained. The range of the obtained optimal filling volume was 0.2mL to 1.2mL.
Conclusion
The optimal filling volume of the oesophageal balloon varies considerably in the paediatric patient.
THE EFFECT OF PRESSURE SUPPORT ON IMPOSED WORK OF BREATHING DURING PAEDIATRIC EXTUBATION READINESS TESTING
Abstract
Background
Paediatric critical care practitioners often make use of pressure support (PS) to overcome the perceived imposed work of breathing (WOBimp) during extubation readiness testing (ERT).
Objectives
Level of WOBimp during ERT with and without added PS and to study its clinical correlate
Methods
Prospective study in spontaneously breathing ventilated children < 18 years undergoing ERT. Using tracheal manometry, WOBimp was calculated by integrating the difference between positive end-expiratory pressure (PEEP) and tracheal pressure (Ptrach) over the measured expiratory tidal volume (Vt) under two conditions: continuous positive airway pressure (CPAP) with and without PS.
Results
112 patients were studied. Median PS d uring the ERT was 10 cmH2O. WOBimp was significantly higher without PS (median 0.27, IQR 0.20 – 0.50 Joules/L) than with added PS (median 0.00, IQR 0.00 – 0.11 Joules/L). Although there were statistically significant changes in spontaneous breath rate (32 (23 – 42) vs 37 (27 – 45) breaths/min, p < 0.001), higher ET-CO2 (5.89 (5.37 – 6.58) vs 6.23 (5.54 – 6.98) kPa, p < 0.001) and expiratory Vt (7.71 (6.60 – 8.82) vs 7.12 (5.83 – 8.08) mL/kg, p < 0.001) in the absence of PS, these changes appeared clinically irrelevant since the Comfort B score remained unaffected (12 (10 – 13) vs 12 (10 – 13), p = NS). Multivariate analysis showed that increases in WOBimp in the absence of PS occurred independent of endotracheal tube size.
Conclusion
Withholding PS during ERT does not lead to clinically relevant increases in WOBimp, irrespective of endotracheal tube size.
Video on Demand
ENERGY LOAD IN MECHANICALLY VENTILATED PAEDIATRIC LUNGS: A BENCH STUDY
Abstract
Background
Mechanical ventilator energy is transferred to the respiratory system and mainly spent to expand the lung parenchyma and overcome resistance of the airways. This has never been measured in mechanically ventilated children.
Objectives
To determine the tidal mechanical energy imparted to the lungs under different conditions in terms of lung size, respiratory mechanics and ventilator settings.
Methods
A bench study was designed to simulate age groups from newborn (endotracheal tube (ETT) 3.0mm) to adolescent (ETT 8.0mm). Pressure (PC) and volume (VC) controlled modes were tested. All possible combinations of respiratory mechanics were simulated. PEEP was set at 5cmH20. Airway and intrapulmonary pressure, including plateau pressure (Pplat) measured at zero-flow state, tidal volume (VT) and flow were recorded. Elastic energy applied to the lung (ELUNG) per breath normalised to body weight was measured from the dynamic pressure –volume curve.
Results
2,652 measurements were performed. ELUNG was higher in VC (p<0.001) and in small ETT sizes (p<0.001). ELUNG was positively correlated with driving pressure (DP) and inflated volume (VT/kg) (r2=0.87 and r2=0.65, respectively, all p<0.001). Best fitting model for predicting ELUNG was a linear combination of DP and VT/kg (R2 = 0.934, p<0.001). ELUNG differed between ventilation modes after stepwise change of compliance (p<0.001). ELUNG was negatively associated with stepwise increase of resistance only in PC ventilation (p<0.001).
Conclusion
DP and inflated volume were the leading mechanical lung energy coefficients. Further studies are needed to delineate the clinical significance of energy load in children and define the “bearable” range as to cause the least lung damage.
Video on Demand
USING TIME-BASED CAPNOGRAPHY TO DETECT INEFFECTIVE TRIGGERING IN MECHANICALLY VENTILATED CHILDREN: A PROOF-OF-CONCEPT STUDY
Abstract
Background
The occurrence of patient-ventilator-asynchrony (PVA) is associated with prolonged duration of mechanical ventilation, especially ineffective triggering. This suggests that real-time monitoring PVA should be developed to improve patient outcome.
Objectives
We propose that ineffective triggering may be identified by a negative deflection in the time-based capnogram. We tested that time-based capnography can be used to detect ineffective triggering and to develop an automated detection algorithm.
Methods
Patients underwent a recording of the ventilator waveforms, electrical activity of the diaphragm and capnogram waveform. Five minutes of the recording were used to identify ineffective triggering events. Ten minutes were used to validate to algorithm.
Results
The waveforms in combination with EMG tracings of the diaphragm identified 161 ineffective triggering events (4.2%) in 3823 breaths. This yielded a total sensitivity of 64% and specificity of 98.6%. Subgroup analysis of the group with ineffective triggering events with a flow > 0 L/min showed a sensitivity of 94.4% and a specificity of 98.4 In total 10800 breaths were used to validate capnogram based ineffective triggering algorithm. This results in a sensitivity and specificity of 95.3% and 99.9%.
Conclusion
Capnography can be used to detect PVA especially those concerning ineffective triggering. Because capnography is readily available in the PICU and is non-invasive this method may have important implications for both clinical and research purposes.