高频振荡(HFOV)通气

高频振荡通气高频通气（high frequency ventilation，HFV）是指通气频率超过150次/分（2.5 Hz, 1 Hz=60次/分）的通气方式。

高频通气是1959年由Emerson首次发展起来的新技术，随着时间的推移逐步衍生出多种高频通气方式。

一般按照其气体运动方式将高频通气分为五类：1.高频正压通气（high frequency positive pressure ventilation, HFPPV）2.高频喷射通气（High frequency jet ventilation，HFJV）3.高频振荡通气（high frequency oscillatory ventilation，HFOV）4.高频阻断通气（High frequency flow interruption ventilation，HFFI）5.高频叩击通气（High-frequency flow interruption ventilation，HFFI）高频振荡通气以其可清除CO2、不易引起气压伤、小潮气量、操作简便、副作用少的优点，在近年来逐渐成为高频通气的首选。

经过多年的经验积累，高频振荡通气在儿科已经成为儿科重症治疗的首选通气方案之一，在ARDS、支气管胸膜瘘等疾病的治疗中，也逐渐扮演着越来越重要的角色。

而其余四种通气方式由于各自的不足，在临床使用中越来越少见。

一、高频振荡通气（HFOV）概述1972年Lukeuheimer等人在心功能研究试验中发现，经器官的压力振动可以使狗在完全肌松的情况下维持时间氧合和动脉血二氧化碳分压正常；与此同时，加拿大多伦多儿童医院Bryan及Bohn等发现应用活塞驱动振荡器对健康狗进行研究时发现，在高频率、低潮气量及远端气道极低压力的时候，动物可维持正常的CO2分压及O2分压，由此开始了人们对高频振荡通气机制的探究。

早期的高频振荡通气仅仅直接在气道上加用振荡器，后来发现这种方法短时间内虽然可以保证氧合和通气，但是长时间使用会造成严重的二氧化碳潴留。

High Frequency Oscillatory Ventilation (HFOV)James Xie, MDPediatric Anesthesiology FellowStanford Children’s Health11/18/2019- Sunday afternoon: you are called by the general surgery team for an emergent ex-lap for suspected necrotizing enterocolitis- Patient is a former 25+5 week infant born after unstoppable preterm labor, now corrected to 29+2- One day prior, patient was put on HFOV due to worsening hypercarbia (arterial PCO2 96) despite high conventional ventilator settings (Vt 5ml/kg, RR 50, PEEP 7)- Current oscillator settings are: MAP 14, Amplitude 32, Frequency 12, I-Time 0.33, FiO2 31% and recent ABG: 7.25/66/70- What is your ventilation strategy for the operation?-Why did the NICU put the baby on the oscillator?-Is this the same or different than high frequency jet ventilation? -How does an oscillator even work?-Can you perform surgery while a patient is on the oscillator?-How do I manage an oscillator? What are all those knobs for? -Can I just switch back to a conventional ventilator?-Is the oscillator working?-Can I transport to the OR on an oscillator?-Can I use nitric oxide while on HFOV?-Can anyone help me??When to use HFOV:1.Persistent Pulmonary Hypertension of the Newborn2.Meconium Aspiration Syndrome3.Air leak syndromes: pneumothorax, pulmonary interstitial emphysema4.Severe Respiratory Distress Syndrome5.Pulmonary hypoplasia6.Failure of conventional ventilation (plateau pressures ≥ 30-35 cmH20 with tidalvolumes of 5-7 ml/kg and severe respiratory acidosis, pH< 7.1)7.Failure of oxygenation (e.g. ARDS)a.SpO2 < 90%, orb.PaO2/FiO2 < 150, despite FiO2 > 60% and optimal PEEP, orc.Oxygenation index (OI) > 15 (where OI = [MAP x FiO2(%)] / PaO2)When not to use HFOV (relative contraindications):1.Obstructive airway disease (HFOV can lead to severe air trapping if used improperly)2.Traumatic brain injury / intracranial hypertension (high MAP can lead to decreasedvenous return, reduced cerebral perfusion)3.Hemodynamic compromise (especially if unresponsive to fluids/vasoactives; )...consider VA ECMO!-HF JV = High frequency jet ventilation (4-11Hz RR, TV ≤ 1ml/kg)-Via a pneumatic valve, short jets of gas are released into the inspiratory circuit => expiration is passive (from elastic recoil)-HF JV is used in conjunction withconventional mechanical ventilation, with application of PEEP (sigh breaths)-Differs from low frequency jet which uses a manually triggered hand-held device -Topics for another day!-HFOV = High frequency oscillatory ventilation (3-15Hz RR, TV ≤ 1-3ml/kg)-Via movement of an electromagnetic diaphragm or piston pump, pressure is generated in the ventilator circuit => active inspiratory and expiratory phases-No sigh breaths for alveolarrecruitment - can easily de-recruit -This is what we are talking about today- A constant distending airway pressure is applied (MAP), over which small tidal volumes aresuperimposed (Power/Amplitude) at a highrespiratory frequency (measured in Hz)-Radial mixing (Taylor dispersion): enhances gas mixing with laminar flow (beyond bulk flow front) -Collateral ventilation: alveoli communicate directly with other nearby alveoli-Coaxial flow: net flow through centre of airway on way down, then on outside of airway on way up-Pendelluft ventilation nearby lung units have different time constants/impedance/phase lags -Cardiogenic mixing: internal ‘wobble’ of heartbeats transmitted to the molecules of gaswithin the lungs causes gas mixingImage source: https:///paper/High-frequency-oscillatory-ventilation-(HFOV)-and-a-Stawicki-Goyal/1196df59f3d6e08db0db881e478c3a8629d43548/figure/4-Yes, it’s been done!-Conditions operated on include: congenital diaphragmatic hernia, congenital cystic adenomatoid malformation, esophageal atresia, PDA, abdominal wall defect, NEC-Advantages:-HFOV minimizes lung movement and interference with the surgical field-Provides continuity in in perioperative ventilatory management-May minimize lung injury, especially in conditions with altered respiratory compliance -Limitations:-Lack of familiarity with HFOV by anesthesiologist-Can’t use inhalational agents (thus TIVA is recommended)-Routine capnography not possible (frequent blood gases, TCOM needed)-HFOV is loud and can hinder clinical exam (e.g. auscultation of heart sounds)Approved by FDA in1991 for use inneonates, used forpatients < 35kg-3100B model: used for patients > 35kg-Approval for use in allpediatrics in 1995-You will likely never adjust bias flow, frequency, or I-time:-Bias flow (allowing further increase in MAP)-< 1 year old: 15-25 L/m,-1-8-year-old: 15-30 L/m -≥8-year-old: 25-40 L/m -Frequency-Preterm neonate: 15Hz (900 bpm)-Term neonate: 12Hz (720 bpm)-Infant/Child: 10Hz (600 bpm)-Older child: 8Hz (480 bpm)-Inspiratory time-Usually set to 33% (I:E ratio of 1:2)-Higher I-times may lead to air trapping-MAP (max ~ 40-45 cm H2O)-Neonates: 2-5 cm above MAP on CMV -Infants/Children: 5-8 cm above MAP onCMV-MAP , if starting immediately on HFOV -Neonates: 8-10 cm H20-Infants/children: 15-20 cmH20-Amplitude/Power: adjust ΔP until there is perceptible chest wall motion from the nipple line to the umbilicus (AKA chest wiggle factor). Initial settings might be:-Wt < 2.0 kg: 2.5-Wt 2.1 - 2.5 kg: 3.0-Wt 2.6 - 4.0 kg: 4.0-Wt 4.1 - 5.0 kg: 5.0-Wt 5.1 - 10 kg: 6.0-Wt > 20 kg: 7.0Patient may be able to tolerate conventional ventilation if your HFOV settings are: -MAP < 16-17 cm-FiO2 < 0.40 - 0.45-Power < 4.0-To convert to CMV, use a MAP 3-4 cm less than the MAP on HFV-Patient SpO2 in the first 30-60 minutes of initiation can change dynamically-Adequate “jiggling” / “wobbling” / “chest wiggle” = patient is being ventilated-CXR to confirm that patient is not hyperinflated (MAP too high)-Transcutaneous CO2 monitoring can help trend CO2-Be aware of changes in lung compliance (e.g. secretions, neuromuscular blockade)-Consider suctioning +/- recruitment maneuver if O2 saturations remain low (but don’t suction too much because it will de-recruit the lungs; use a closed suction system if possible)-NICU respiratory therapists can assist with TCOM setup and use-Try to correlate with blood gas measurements to assess ventilationQuick Troubleshooting GuidePoor Oxygenation Over Oxygenation Under Ventilation Over Ventilation Increase FiO2Decrease FiO2Increase amplitude Decrease amplitudeIncrease MAP* (1-2cmH2O)Decrease MAP(1-2cmH2O)Decreasefrequency**(1-2Hz) if amplitudeMaximalIncreasefrequency**(1-2Hz) if amplitudeMinimal* Consider recruitment maneuvers ** Changes in frequency are rareminute-This means the absolute inspiratory time is increased -If the I:E ratio is fixed at 1:2, the delta P for a given MAPwill lead to a larger tidalvolume being delivered/rs/carefusioncorporation/images/rc_3100a-pocket-guide.pdf-Can I transport with HFOV?-Sort of? - It would require multiple tanks of O2 and a battery pack. Ifpatient is too unstable for transport,consider doing the procedure atbedside-Moving a patient while on HFOV has been described in the literature (Leeet al 2012: Using the HighFrequency Ventilation duringNeonatal Transport)--Yes! This is well described, especially in the PPHN population-Kinsella et al (1997): “Randomized, multicenter trial of inhaled nitric oxide and high-frequency oscillatory ventilation in severe, persistent pulmonaryhypertension of the newborn” found that “treatment with HFOV plus iNO is often more successful than treatment with HFOV or iNO alone in severePPHN”Ask for help!-Respiratory therapy team-RT Supervisor x 19613-OR RT on Voalte-NICU MDs-HFOV is a useful ventilatory modality that can provide lung protective ventilation/oxygenation, especially when conventional ventilation is inadequate-HFOV can be safely and effectively continued intraoperatively-HFOV delivers an unknown tidal volume -> must check blood gases or trend TCOMs -Not wiggling = not ventilating-Higher MAP = more oxygenation-Higher amplitude (delta P or power) = more ventilation-It is highly unlikely you will need to adjust the I-time, frequency, or bias flow-Have a plan for transport (or not-transporting if patient is too unstable)-You can use nitric oxide, but not volatile agents. Plan on TIVA.-When in doubt, ask for help!Wibble Wobble: High Frequency Oscillatory Ventilation (https:///2019/02/hfov/)Bouchut JC, Godard J, Claris O. High-frequency oscillatory ventilation. Anesthesiology. 2004;100(4):1007-12. (https:///article.aspx?articleid=1943214)Klein, J. Management strategies with high frequency oscillatory ventilation (HFOV) in neonates using the SensorMedics 3100A high frequency oscillatory ventilator(https:///high-frequency-oscillatory-ventilation-hfov-neonates-3100A-ventilator)CareFusion. 3100A High Frequency Oscillatory Ventilator Pocket Guide(/rs/carefusioncorporation/images/rc_3100a-pocket-guide.pdf)。

高频振荡通气治疗重度新生儿呼吸窘迫综合症27例临床分析【摘要】目的探讨重度新生儿呼吸窘迫综合症患儿中采用高频振荡通气治疗临床特点及疗效。

方法回顾性分析了2010年1月——2012年5月我院新生儿科对收治的27例重度新生儿呼吸窘迫综合症患儿采用高频振荡通气治疗的临床完整资料。

结果本组27例重度新生儿呼吸窘迫综合症患儿经过高频振荡通气治疗后，病变好转20例，治疗好转率74.1%，自动放弃治疗出院后死亡7例，死亡率25.9%。

本组幸存者无一例发生气漏。

治疗前后的动脉血氧分压、二氧化碳分压、氧合指数的改善差异性具有比较意义（p<0.05）。

结论高频振荡通气作为肺保护措施能更好地改善新生儿呼吸窘迫综合症患儿的肺氧合功能，迅速、持续地增加气体的交换量，并可有效减少气压伤及并发症。

但选择高频振荡通气模式及设置合理的参数是重度新生儿呼吸窘迫综合征患儿抢救成功的关键。

【关键词】新生儿呼吸窘迫综合症；重度；高频振荡通气；疗效新生儿呼吸窘迫综合征（nrds）指新生儿出生后已有了短暂（数分钟至数小时）的自然呼吸，继而发生进行性呼吸困难、发绀、呻吟等急性呼吸窘迫症状和呼吸衰竭。

多见于早产儿[1]、过低体重儿或过期产儿。

患儿肺内形成透明膜为其主要病变，故又称新生儿肺透明膜病。

重度新生儿呼吸窘迫综合症是指肺泡广泛萎陷，肺通气和换气功能障碍，因此，及早进行机械通气和并积极实施肺复张措施，有效改善肺通气和换气，提高氧合程度是治疗的关键措施。

高频振荡通气（hfov）是近年出现的一种新型机械通气方式。

高频振荡通气采用肺保护通气策略，能够在不增加气压伤的前提下，有效提高氧合，进而降低通气时间，降低肺气漏等并发症，已经越来越广泛地应用于临床[2]。

2010年1月——2012年5月我院新生儿科对收治的27例重度新生儿呼吸窘迫综合症患儿采用高频振荡通气治疗，其疗效较好，现总结如下。

1资料与方法1.1一般资料本组病例选自我院新生儿科2010年1月——2012年5月收治的27例重度新生儿呼吸窘迫综合症患儿中，男性15例，女性12例，胎龄25周-36周；体重850g-2600g。