1、UPDATE ON HIGH FREQUENCY OSCILLATORY VENTILATION IN THE NICU 高频振荡通气新动态,新加坡竹脚妇幼医院新生儿科主任 萨米尔 拉惹杜莱医生 Dr VS RajaduraiSenior Consultant & Head of NICU Dept of Neonatology KK Womens and Childrens Hospital,UPDATE ON HFOV 纲要,Background / Introduction 简介Animal Studies 动物研究Clinical Management Strategies 医疗策略C
2、omplications of HFOV并发HFOV use in term infants 用于足月儿HFOV use in preterm infants用于早产儿Evidence from RCTs (Cochrane Review)随意对照研究循证,HFOV: DEFINITION 高频振荡通气定义,very rapid rate (高频率) 300 - 1200 BPMsmall tidal volumes frequently less than dead space潮气量 通常比死腔来得小 active inspiration and expiration 主动吸气及呼气,HFO
3、V : REASONS FOR DEVELOPMENT 高频振荡通气发展原由,1. To reduce ventilator associated lung injury by- preventing volutrauma 容量伤 - reducing oxygen exposure 减低氧气接触- reduce incidence of CLD减低慢性肺病机率2. To provide a method of assisted ventilation that allows severe pulmonary airleaks to heal探寻可治肺气漏的通气的方法,DIFFERENCES
4、BETWEEN HFOV & CONVENTIONAL VENTILATION 高频振荡通气与常规机械通气比较,CMV HFOV Rate (BPM) 呼吸频率 0-120 300-1200 Tidal Volume潮气量 (ml/kg) 4-20 0.1-5 Alv pressure 肺泡压力(cm/H20) 5-50 0.1-5 End-expiratory LV 呼气末压 low 低 high高 Expiration 呼气 passive被动 active主动,Characteristic Parameters of HFV 参数特征,GAS EXCHANGE DURING HFOV 高
5、频振荡通气的气体交换,MECHANISMS 机制:,Enhanced molecular diffusion near the alveolar - capillary membrane 增进肺气泡毛细管渗滤Enhanced convection促进对流 (Pendelluft effect摆动效应)Taylor dispersion 泰勒弥散现象Reduced dependence on bulk convection减低对大容积对流依赖,Taylor-Dispersion,Intraalveolar Pendelluft,TYPES OF HFO VENTILATORS 高频振荡通气呼吸机
6、类型,Diaphragm HFOV 隔膜型e.g.: Sensor Medics 3000AIE ratio 1:2 Most powerful Piston HFOV 活塞泵型 e.g.: Hummingbird Variable IE ratio 1:1 - 1:2 Hybrid devices: 混杂型Spinning wheel or ventures to generate negative pressures during expirationIE ratio 1:1e.g.: SLE HFO 5000，Drager Babylog 8000,HFOV DEVICES: EFFIC
7、ACY 高频通气器械效能,Mechanics, operation and run-time adjustment of the devices are quite different None of them are similar enough to be controlled in exactly the same manner 机械功能各异 NO human studies have directly compared different types of HFOV仍未有比较用在人类各类高频通气机的研究报告 Currently, impossible to say if one typ
8、e is better than the other 目前难说何类型为优,HFOV: ANIMAL STUDIES 高频通气机的动物研究(1),Lavaged rabbit, lavaged monkey premature baboon,Reported Benefits 好处是:,Decreased hyaline membranes 减少透明膜More uniform lung expansion均匀肺膨胀Improved gas exchange 增进气体交换Decreased edema & alveolar-capillary leak减低水肿及 气泡-毛细管漏Normalizat
9、ion of pressure-volume curves使压力-容量曲线图正常化Improved surfactant effect (Synergism)促进表面活性物质效应Decreased lung injury 减轻肺损伤,HFOV: ANIMAL STUDIES 高频通气机的动物研究 (2),Best results were obtained 最佳结果是:,When HFOV was initiated early 及早使用Use of high volume (volume recruitment) strategy使用高容量策略When over-expansion & at
10、electasis were avoided先避免过渡膨胀,HFOV: PRACTICAL MANAGEMENT 高频通气机实践处理,Prior to starting HFOV 使用前：,Get a baseline CXR 胸X光片 (基线)监控Trancutaneons PCO2 & SPO2 monitoring & invasive arterial BP monitoring establishedOptimise blood pressure & perfusion (volume replacement & inotropes) 稳定血压Use low compliant ve
11、ntilator circuits使用低顺应性呼吸机回路Sedation with morphine 吗啡镇静剂,HFOV: VENTILATORY STRATEGIES 高频通气策略,1. High (optimal) volume strategy2. Low volume strategy高容量 及 低容量控制通气 策略,HFOV: HIGH VOLUME STRATEGY 高容量策略 (1),Used in symmetrical uniform lung diseases 用于 (RDS, ARDS, Pulmonary edema)Initial Settings 启用调定点:MA
12、P平均气道压力 : 2cm greater than CMVFrequency频率: 10HzAmplitude (P): Enough to get perceptible chest 幅度 wall motionInsp Time 吸气时间 : 33% (sensor medics)1:1 (other ventilators),HFOV: HIGH VOLUME STRATEGY 高容量策略 (2),Initial use of higher MAP than CMV启用比持续控制通气较高的平均气道压力 Use of alveolar recruitment manoeuvres 肺泡复
13、张手法 呼吸机撤离指标：Initial weaning of FiO2 before MAP,HFOV: HIGH VOLUME STRATEGY 高容量策略 (3),Gradually increase MAP by 1-2cm H2O until adequate oxygenation occurs & FiO2 0.30 is reachedOptimising lung inflation is essentialCase must be taken to avoid lung overinflationDo chest x-ray 1-2 hours later,Lung Recr
14、uitment Strategy肺泡复张手法,HFOV: HIGH VOLUME STRATEGY 高容量策略 (4),Optimal inflation: Top margin of right doom of diaphragm at the 8th or 9th rib, lung aeration goodOver-inflation: Right hemidiaphragm 10th ribs Intercostal bulgingUnder-inflation: Right hemidiaphragm higher than upper margin of 8th rib & un
15、der aerated lung fields,Radiological Evaluation X光片评估,HFOV: CONTROL OF VENTILATION 控制通气调整幅度,Mainly by adjusting amplitude (P)Higher amplitude will increase tidal volume and hence CO2 removal and vice versaSmall changes in amplitude may associated with marked changes in ventilation (CO2)Adjustment gu
16、ided by adequacy of chest wall movement or TCPCO2Fine tune: Repeated small adjustments preferable to infrequent large changes,HFOV : VENTILATORY STRATEGIES 低容量策略,Low-Volume Strategy:Used in asymmetrical lung diseases (airleak, pneumonia, MAS)MAP same as that of CMVAlter amplitude and frequency to ac
17、hieve optimal ventilation,HFOV: FREQUENCY 频率,Ranges used: 5 - 15 HzOptimal Frequency of oscillation may be different in different disease statesVLBW infants: 12 HzTerm infants : 10 HzLower Frequency: 6 - 8 Hz,a) MAS with air trapping b) ventilated infants 2 weeks (airway resistance is increased) c)
18、pulmonary hypoplasia d) very stiff (non-compliant) lungs e) chronic lung disease,TARGET RANGES FOR BLOOD GAS VALUES 所要达到血气值的目标,SpO2: 85% - 95% Preterm 早产儿90% - 98% Term 足月儿pCO2: 40 - 50 mmHgpH : 7.25 - 7.4In infants with PIE, Pneumothorax, hypoplastic lungsPCO2 50 - 60 mmHgPH 7.20,HFOV : VENTILATORY
19、 STRATEGIES 高频通气策略,Assess the infants pulmonary pathophysiology Determine which mechanism is predominantly responsible for gas exchange defect- Symmetrical OR Asymmetrical- Atelectrasis - Airleak- Air trapping- Airway obstruction - pulmonary blood flowAdopt optimal strategy Re-evaluate frequently an
20、d change the ventilator settings,WEANING FROM HFOV撤出高频通气,PRINCIPLES 原则,FiO2 should be weaned first in response to good oxygenationDecrease FiO2 to 30%Decrease MAP in 1cm H2O steps based on ABG & SPO2Wean amplitude based on PCO2 levelsAn attempt should be made to wean MAP or amplitude every 6-12 hour
21、sMaintain optimal lung inflation and avoid atelectasis during weaningAt a MAP of 6-8 cm H2O (VLBW infants) & 8-10 cm H2O (larger infants)- Change to CMV- Extubate to Head box or nasal prong CPAP,HFOV: COMPLICATIONS 高频通气的并发,Lung over-inflation, Air leak 气漏Adverse cardiopulmonary interactions 心肺并发Gas
22、trapping 空气被堵住Mucostasis 粘液滞积Necrotising tracheobronchitis 坏死性气管支气管炎Intraventricular haemorrhage 脑室出血,TROUBLESHOOTING DURING HFOV 高频通气问题原由 (1),LOW PaO2 低动脉血氧分 压 :,sub-optimal lung recruitment increase MAPover-inflated lungreduce MAP by 2cm H2O & see the responseCXRcheck water level in Humidifier Cha
23、mbercheck there is NO water in the ventilator circuit, ETT/T-pieceair leakPPHN - consider pulmonary vasodilator,TROUBLESHOOTING DURING HFOV 高频通气问题原由 (2),HIGH PaCO2高动脉血二氧化碳分 压 :,check water level in Humidifier Chamber, water in circuitinsufficient alveolar ventilaton increase amplitudeblocked ET tube
24、air leakunder inflated lungs (Amplitude delivered on non-compliant part of P-V curve (Point A)over inflated lungs (Amplitude being delivered on non- compliant part of P-V curve (Point C) Increased airway resistance (MAS, BPD). HFOV may be inappropriateIf all the above seem ok, try reducing oscillato
25、r frequency & see the response,TROUBLESHOOTING DURING HFOV 高频通气问题原由 (3),PERSISTING HYPOTENSION 持续低血压:,give additional volume 10ml/kg of normal salineconsider over-distension. Reduce MAP & see the response,HFOV : PRATICAL ISSUES 高频通气实践问题 (1),Tried HFOV but did not work! 未能奏效 Ensure blood volume and b
26、lood pressure Ventilator tubing should be non-compliant (e.g. Drager Babylog) Check water level in the Humidifier chamber Is the MAP too high ?Do chest x-ray: Pneumothorax，PIE Assess the need for pulmonary vasodilator Patiently stand at the bed side; trial and error adjustments,HFOV : PRATICAL ISSUE
27、S 高频通气实践问题 (2),Small change in frequency or P may produce marked changes in CO2 eliminationContinuous non-invasive monitoring of pCO2 (TcCO2) is essentialAvoid wide fluctuations of pCO2 levelsAfter ET suctioning:- Increase MAP by 2cm H2O for 15-30 mins- Critical opening pressure must be reached befo
28、re lung recruitment occurs,HFOV : TERM & NEAR-TERM INFANTS 足月及近足月儿的高频通气 (1),Rescue of potential ECMO candidates: BW 2000g, GA 34 wks n = 79Treatment Failure:CV 60% vs HFOV 44% (p = ns)63% of those who failed responded to HFOV compared to 23% in whom HFOV failed (p = 0.03)Clark et al. J Pediatr 1994;
29、124:447-54,HFOV : TERM AND NEAR TERM INFANTS 足月及近足月儿的高频通气 (2),Combination therapy:HFOV + INO more effective than CMV + INO or HFOV alone in infants with RDS / MASSignificance of optimising lung inflation for effective INO therapyKinsella et al. J Pediatr 1997;131:55-62,HFOV IN NEAR TERM AND TERM INF
30、ANTS 足月及近足月儿的高频通气 (3),Rescue HFOV vs CMV for infants with severe pulmonary dysfunctionNo significant differences in the need for ECMO (RR 2.05, 95% CI 0.85 - 4.92)No significant reduction in mortality at 28 days (RR 0.51, 95% CI 0.05 - 5.43), ventilator/oxygen days or days in hospitalBhuta T, Clarke
31、 RH, Henderson-Smail DJ. The Cochrane Library, Issue 1, 2004,HFOV & SURGICAL NEONATE 外科婴儿的高频通气 (1),Increased intra-abdominal pressureElevation of Diaphragm Reduced Diaphragmatic movementBasal atelectasis Reduced lung complianceRespiratory failure Haemiodynamic compromise Examples: Necrotising entero
32、colitis ExompholosPost-operative CDH Gastroschisis,HFOV & SURGICAL NEONATE 外科婴儿的高频通气 (2),8 infants, birthweight 600-3200g, gestation 25-38 weeks Intra-abdominal pathologies resulting in severe abdominal distension and respiratory failure Failure of CMVHFOV improved gas exchange within an hour and th
33、e improvements were sustained for 48 hoursFok et al. HFOV in infants with increased intra-abdominal pressure. Arch Dis Child 1997;76:F123-25,HFOV USE IN PRETERM INFANTS 早产儿的高频通气 (1),Does HFOV reduce the incidence of CLD ?Should HFOV be used as a primary (Elective) mode or rescue tool ?Safety : Is HF
34、OV associated with IVH or PVL ?,HFOV : AS RISK FACTOR FOR IVH / PVL 高频通气与IVH/PVL 风险 (1),Possible mechanisms:Pulmonary hyperexpansion or high intrathoraric pressure leading to cerebral venous congestionWide fluctuations of pCO2 levels and hypocarbia,ELECTIVE HFOV IN PRETERM INFANTS 早产儿与选择性高频通气 (1),He
35、nderson - Smart DJ et al. Elective HFOV vs conventional ventilation for acute pulmonary dysfunction in preterm infants (Cochrane Review). The Cochrane Library 2004, 1:Update Software, Oxford.,11 RCTs on 3275 infants were analysedMortality: Not significantly different by 28-30 days or by 36-37 weeks
36、or discharge,ELECTIVE HFOV IN PRETERM INFANTS 早产儿与选择性高频通气 (2),CLD in survivors at 28 - 30 days overall: Trend towards reduced incidence RR 0.86 (0.74, 1.01) HVS (3 trials): RR 0.53 (0.36, 0.76)CLD in survivors at 36 - 37 weeksoverall: significant decrease in the HFOV groupRR 0.88 (0.79, 0.99)RD - 0.
37、04 (-0.08, 0.00)HVS (8 trials): RR 0.88 (0.79, 0.99)RD - 0.06 (-0.11, -0.02)significant heterogeneity,ELECTIVE HFOV IN PRETERM INFANTS 早产儿与选择性高频通气 (3),IVH of all gradesoverall analysis: RR 1.05 (0.96 - 1.15)No HVS: Trend towards a small increase RR 1.16 (0.99, 1.37)Severe IVH (Grade 3 &4)overall ana
38、lysis: significant increase in the HFOV group RR 1.45 (1.09, 1.93)RD 0.07 (0.018, 0.13), NNH 14PVLoverall: No significant differenceNo HVS: significant increase in HFOVRR 1.64 (1.02, 2.64)RD 0.41 (0.002, 0.08), NNH 24.4,REVIEWERS CONCLUSIONS 审稿者结论 (1),No reduction in mortalitySmall reduction in CLD
39、with HFOVAdverse effect on short term neurological outcomes if HVS is not used,No clear evidence that elective HFOV, as compared to CMV, offers important advantages when used as the initial ventilation strategy to treat preterm infants,HFOV IN PRETERM INFANTS 早产儿与高频通气,Reasons for contradictory resul
40、ts:Age of randomisation (birth to 12 hours) Wide variation in BW and GA of enrolled population Differences in antenatal steroids / surfactant use Chorioamnionitis & lung damage Different ventilatory strategies Differences between devices Investigators experience,LEARNING CURVE WITH HFOV 高频通气学习途中,RES
41、CUE HFOV VS CMV IN PRETERM INFANTS 营救高频通气和传统通气,Bhuta T, Henderson-Smart DJ. The Cochrane Library, Issue 1, 2004.,only one RCTReduction in new air-leakRR 0.73 (0.55, 0.96)RD -0.17 (-0.32, -0.027)NNT 6 (3, 37)Significant increase in the rate of IVH (any grade)RR 1.77 (1.06, 2.96)RD 0.156 (0.02, 0.29)N
42、NH 6 (3, 50)Strong but non-significant trend towards increase in severe IVHNo difference in mortality of CLD at 30 days,REVIEWERS CONCLUSIONS 审稿者结论 (2),Insufficient information on the use of rescue HFOV to make recommendations for practiceData suggest that harm may outweigh any benefitNeed for more RCTs,THANK YOU,Email: .sg,
