1Mater Mothers' Research Centre, Mater Health Services, Brisbane,. Australia 2Paediatric ... 1Newborn Services, Royal Women's Hospital, Melbourne, Australia.
PSANZ 2010 14th Annual Congress Wellington Convention Centre
ORAL ABSTRACTS
8 Oral Abstracts
A001
A003
CATHETER SIZE EXERTS THE GREATEST INFLUENCE ON END-EXPIRATORY LUNG VOLUME DURING CLOSED SUCTION IN HIGH-FREQUENCY JET VENTILATION
STABILITY OF END-EXPIRATORY LUNG VOLUME SIGNAL IN THREE DIFFERENT RESPIRATORY INDUCTIVE PLETHYSMOGRAPHS
Tingay DG1,2,3, Bhatia R2,3, Hepponstall M1,2, Loughnan P1, Copnell B1,4 1 Royal Children’s Hospital , Melbourne, Australia 2Murdoch Childrens Research Institute, Melbourne, Australia 3Royal Women’s Hospital, Melbourne, Australia 4Monash University, Melbourne, Australia
Bhatia R1,2, Owen LS1,2, Davis PG1,2, Tingay DG1,2,3 1 Royal Women’s Hospital, Melbourne, Australia 2Murdoch Childrens Research Institute, Melbourne, Australia 3Royal Children’s Hospital, Melbourne, Australia
Background: ETT suction during high-frequency jet ventilation (HFJV) has never been studied. Aim: To compare the effect of different closed suction (CS) methods during HFJV on tracheal pressure (Ptrach) and end-expiratory lung volume (EELV) in a rabbit model. Method: Six anaesthetised and muscle-relaxed adult rabbits without lung injury were ventilated with HFJV (Bunnell Life-Pulse) at a PEEP of 3– 6 cmH2O, TiHFJV 0Æ02 s, PIPHFJV 20 cmH2O and RHFJV 300. CS was performed at -100 mmHg for 6 s using 6 and 8FG catheters inserted over 10 s, with either HFJV pulses running during insertion and suction (continuous HFJV), only during suction or off. The protocol was repeated using postsuction CMV sigh-breaths at 3 bpm. Before, during and for 60 s after CS Ptrach, total and regional EELV (EIT) were measured. Results: Ptrach was mean (95%CI) 199 (16 3, 23 5) cmH2O (t-test) lower during 8FG catheter CS, and not influenced by HFJV activity permutations. Overall, catheter insertion caused a mean (SD) DEELV from pre-suction of 2Æ9(6Æ5) ml/kg, Compared to -6Æ6(9 2) ml/kg during CS and 0Æ3(1Æ5) ml/kg 60 s post-suction (P < 0Æ0001 ANOVA). For each catheter size maximum DEELV did not differ between permutations. 8FG CS caused a maximum DEELV 10 (5Æ8,14Æ2) ml/kg lower than 6FG (t-test). Only 8FG without sighbreaths (all permutations) resulted in a 60 s EELV lower than pre-suction, but this only differed from 6FG with sigh-breaths (all P < 0Æ05; ANOVA posthoc analysis). Regional EELV data will be presented at meeting. Conclusions: Catheter size and, to a lesser extent, CMV sigh-breaths influence suction related DEELV, not jet activity, during HFJV.
Background: Despite recognition of the importance of maintaining adequate end-expiratory lung volume (EELV) bedside measurement techniques during mechanical ventilation are lacking. Respiratory inductive plethysmography (RIP) in DC-coupled output is a reliable method for measuring change in EELV in ventilated newborns. However, it is temperature-sensitive and subject to drift. Aims: To compare differences in baseline drift and hence stability of EELV signals between three RIP devices; RespitraceTM 200 (Non-Invasive Monitoring Systems) Somnostar QDC (Sensormedics) and BicoreTM II (Carefusion). Methods: In a benchtop setting, time to signal stability and subsequent baseline drift were determined in the three DC-coupled output RIP devices at room temperature. Each RIP device was attached to a custom-made fixed volume cylinder using Respibands (Respibands Plus, USA) and left undisturbed. The raw EELV signal (Volts) was measured (200 Hz) for 6 h after turning on the machine. All measurements were taken at room temperature. Six recordings were taken with each device. A drift of ± 3% was considered acceptable (Drager flow sensor ± 6% error). Results:
A002
LUNG DERECRUITMENT RELATED TO ENDOTRACHEAL SUCTION IN VENTILATED PRETERM INFANTS Hough JL1,2, Shearman AD1,2, Liley HG1, Schibler A1,2 1 Mater Mothers’ Research Centre, Mater Health Services, Brisbane, Australia 2Paediatric Critical Care Research Group, Mater Health Services, Brisbane, Australia Background: Endotracheal suction often affects oxygen saturation and other variables, possibly due to partial lung collapse. We studied the effects of suction on regional lung volume and ventilation. Method: DEELV (change in end expiratory lung volume) and VT were measured in ventilated preterm infants using electrical impedance tomography (EIT). Recordings were taken before, during, and each 15 min for 2 h after suction performed via a valved suction port. Settings and lung function variables were downloaded from the Dra¨ger Babylog 8000+ ventilator and physiological variables were recorded. Results: Eighteen infants were studied [mean (SD) GA 26Æ5 (18) weeks; age 19 (1Æ2) days; CRIB score 10Æ3 (3Æ4). Whole lung DEELV decreased by 3Æ5% after removal of the flow sensor, and a further 1% after suction. By 15 min post-suction and for at least the next hour, EELV was 2% higher than presuction. VT and MV were both significantly greater (P < 0Æ01) 15 min after suction than before and during suction. Oxygen saturation was significantly lower during suction (P < 0Æ01) than both before and during the h after suction despite increases in inspired oxygen during suction. Conclusions: Disconnection of the flow sensor from the ventilatory circuit results in a reduction in lung volume which is exacerbated by endotracheal suction. Interventions to limit the loss of lung volume with flow sensor removal and suction need to be investigated.
No. of recordings Median (range) Median (range) that reached time to reach drift post stability stability (min) stability (%) RespitraceTM 200 4 Somnostar QDC 3 BicoreTM II 6
88 (50–15) 70 (45–75) 12 (5–35)
3 8(2 8–5 2) 11 4 (1 4–12 8) 0 3 (-1 5–1 7)
Conclusions: In contrast to the other two devices, BicoreTM II reaches stability quickly and appears to have little or no clinically significant drift. The Somnostar and RespitraceTM 200 require at least 70 min warm-up time before patient use. Once stability was reached, the RespitraceTM 200 demonstrated minimal drift. A004
SELECTING THE CIRCUIT FLOW FOR INFANTS VENTILATED USING ASSIST CONTROL VOLUME GUARANTEE Wheeler KI1,2,3, Wong C1, Morley C1, Davis P1,3,4 1 Newborn Services, Royal Women’s Hospital, Melbourne, Australia 2 Department of Physiology, Monash University Melbourne, Australia 3 MCRI, Melbourne, Australia 4University of Melbourne, Melbourne, Australia Background: Assist control/volume guarantee (AC/VG) mode is used to deliver volume targeted ventilation. The ventilator adjusts peak inspired pressure (PIP) in response to expired tidal volume (VT). The circuit flow and inspiratory time settings affect delivered PIP. It has been suggested that using lower circuit flows may allow for more gentle ventilation and a more physiological flow waveform. We studied the effects of circuit flow settings during AC/VG ventilation. Method: Crossover trial of stable infants ventilated using AC/VG with a fixed inspiratory time of 0Æ3 s. Flow settings of 4, 6 and 8 l/min were studied in random order. Ventilator data, heart rate, FiO2, SpO2 and transcutaneous CO2 measurements were recorded. Results: Twenty four infants were studied. Median (IQR) corrected gestation, weight and FiO2 were 27 (26–30) weeks, 0Æ79 (0Æ73–1Æ28) kg and 0Æ23
Journal of Paediatrics and Child Health 46 (Suppl. 1) (2010), 7–55 2010 The Authors. Journal Compilation 2010 Paediatrics and Child Health Division (Royal Australasian College of Physicians)
PSANZ 14th Annual Congress 2010 9
(0Æ21–0Æ28) respectively. At settings of 4, 6 and 8 l/min, median (IQR) PIP was, 16 (11–21), 15 (13–21) and 18 (15–22) cmH2O. Cardiorespiratory parameters were stable at all settings. With a flow set to 4 l/min, fewer inflations reached pressure waveform plateaux, and one infant did not attain target VT when leak increased. In five infants weighing over 1Æ25 kg, infrequently brief negative airway pressure was noted, predominantly at settings of 4 and 6 l/min. Conclusions: Infants were stable when ventilated using AC/VG with flow settings of 48 l/min. We suggest caution when using lower circuit flows in larger infants and those with significant leak. Further studies should investigate variable inspiratory times and longer term outcomes.
A005
VENTILATOR GENERATED NASAL INTERMITTENT POSITIVE PRESSURE VENTILATION (NIPPV): EFFECTS OF ALTERING GAS FLOW RATES, A CROSSOVER STUDY Owen LS1,2, Morley CJ1,2,3, Davis PG1,2,3 Royal Women’s Hospital, Melbourne, Australia 2Murdoch Children’s Research Institute, Melbourne, Australia 3University of Melbourne, Melbourne, Australia
1
Background: Optimal NIPPV delivery may be compromised by the inability to achieve the desired peak inflation pressure (PIP). The effect of increasing gas flow rates on delivered PIP, gas exchange and respiratory pattern during NIPPV has not been investigated. Aim: To investigate the effects of altering the circuit gas flow during ventilator generated non-synchronised NIPPV. Methods: We studied 10 infants (three female, seven male, median gestation 25+3 weeks, birth weight 797 g and postnatal age 29 days). Infants were studied for30 min at three gas flow levels in random order: the flow set by the clinical team and flows of both 2 l/min above, and below, this level. Delivered pressures, oxygen saturations, transcutaneous oxygen and carbondioxide levels, heart and respiratory rates, inspired oxygen and video images were recorded. Data were digitised and recorded using Spectra software. Results: Delivered PIPs were significantly higher with increasing flow rates (11Æ1 cmH2O, 14Æ7 cmH2O and 17Æ9 cmH2O), and a higher proportion of inflations reached a PIP at least 2 cmH2O above the end expiratory pressure level (62Æ8%, 997% ad 100%). As flow rates increased higher transcutaneous oxygen levels were seen (41 3 mmHg, 44 8 mmHg and 49 2 mmHg). At the highest flow rate time spent with oxygen saturations
