This presentation was a large portion of a college project, in which a professional level of work was expected.

1. High-Frequency Oscillatory Ventilation in Adult Patients Sarah Adams RT 214 December 9, 2010

2. Objectives Six W’s and One H What is HFOV? Why should HFOV be used? Who would this benefit? When should HFOV be considered? Where do you start? How is HFOV implemented? Weaning

3. What is HFOV? Alternative mode of ventilation Based on protective “open lung” principles Keep it simple: CPAP with a wiggle Continuous airway pressure (mPaw and bias flow) keeps the lungs open Oscillatory movement (amplitude and frequency) produces Vt Vt is often less than deadspace

4. What is HFOV? SensorMedics 3100B Only oscillator FDA-approved for use with adult and pediatric patients weighing > 35 kg Uses a magnetically-driven reciprocating piston Forward and backward movement of piston creates active inhalation and exhalation

5. Why should HFOV be used? Rescue therapy ARDS patients who are failing CMV Prophylactically At-risk patients Decreases the risk of developing VILI/VALI Derdak et al (2002) found that there was a reduction in inflammatory mediator levels with HFOV as compared to CMV when applying similar mPaw values

6. Why should HFOV be used? Lung Protection The entire ventilatory cycle is contained within the “safe zone” Overdistension and derecruitment are avoided HFOV CMV INJURY INJURY INJURY INJURY

7. Who would this benefit? ARDS patients Patients at-risk for developing VILI/VALI Special subpopulations: Major Burn Trauma Traumatic Brain Injury

8. Who would this benefit? Major burn patients 54% of patients on CMV develop ARDS Treatment of ARDS in burn patients is two-fold and HFOV can supplement both aspects First, support hypoxemic patient with noncompliant lungs Second, surgical excision and wound closure Cartotto et al (2005) states that the need for burn wound surgery influences their decision to start HFOV before surgery due to patients’ rapid improvement in oxygenation

9. Who would this benefit? Major burn patients with smoke inhalation injury Improvement in oxygenation was slower and less substantial 72 hrs for improvement, compared to 12 hrs for burn-only patients Cartotto does not consider smoke inhalation injury a contraindication

10. Who would benefit? Trauma patients HFOV has been found to significantly improve oxygenation in patients with blunt trauma Severity of traumatic injury and organ system failure are greater predictors of survival than respiratory parameters in these patients The Adult HFOV Outcome Assessment has been found to be non-reliable in these patients, the mortality prediction is lower than actuality

11. Who would this benefit? Traumatic Brain Injury Patient mortality was found to be much less than the predicted value calculated from the Adult HFOV Outcome Assessment Lung protective strategies and brain protective strategies appear contradictory Permissive hypercapnia v. normocapnia goals However, improvement has been noted in both oxygenation and ICP Continuous monitoring of ICP, CPP, and PaCO2 is needed

12. When should HFOV be considered? Criteria recommended by SensorMedics: FiO2 ≥ 60 PEEP ≥ 10 PaO2/FiO2 ratio < 200 Plateau pressure > 30 cmH20 Oxygenation Index (OI) > 24 Bilateral infiltrates on a chest x-ray consistent with ARDS Contraindications: None, although HFOV may be less effective in COPD/asthma patients due to air-trapping and hyperinflation

13. When should HFOV be considered? Oxygenation Index (OI) From respiratory standpoint – primary indicator of mortality Calculated as: OI = FiO2 x mPaw Experts agree: Early intervention produces better outcomes PaO2

14. When should HFOV be considered? Ideally, the patient should be hemodynamically stable MAP ≥ 75 mmHg If MAP <75 mmHg, fluid boluses and vasopressors pH > 7.20 If pH ≤ 7.20, aggressive measure should be taken before transition Manipulation of PaCO2 is significantly slower than on CMV

15. When should HFOV be considered? After STAT procedures which cannot be performed in the unit(CT scans, MRIs) Oscillator is not able to be used during transport Electrical needs exceed battery capability Requires two separate pressurized gas sources After the airway is deemed to be patent Suction If there are concerns about airway patency, bronchoscopy recommended

16. When should HFOV be considered? After patient sedation/paralysis Spontaneous respirations by the patient can interfere with the oscillator’s ability to effectively ventilate Large changes in pressure will cause the ventilator to alarm and the oscillatory function to pause Patient will receive only bias flow of gas when the oscillatory function is paused

17. Where do you start? Become familiar the machine Control panel Piston Disposable diaphragm Non-compliant patient circuit Water trap Heated humidifier (not seen) Blender (not seen)

18. Where do you start? Become familiar with the control panel/parameters mPaw Power Frequency Inspiratory time percent (Ti%) Bias flow

20. Where do you start? mPaw Adjustment knob manipulates a balloon valve in the expiratory limb of the patient circuit Balloon valve is able to restrict the flow of expiratory gas (PEEP) Determines lung volume Primary control for oxygenation An incorrectly set bias flow can either hinder or enhance mPaw

21. Where do you start? Power Control knob adjusts amplitude, which is shown on a numerical display Amplitude is the change in pressure created by the forward and backward movement of the piston This pressure gradient determines Vt Primary control for ventilation

22. Where do you start? Frequency Adjusts the amount of time the piston is allotted for forward and backward movement Value is measured in Hertz (Hz) 1 Hz = 60 cycles(breaths)/minute Secondary control for ventilation Relationship between frequency and Vt is inverse As frequency increases, volume displacement decreases, which results in a decreased Vt

23. Where do you start? Inspiratory time percent (Ti%) Adjusts I:E ratio Allots the percent of time the piston spends in forward motion during one ventilatory cycle Default setting is 33% (I:E ratio of 1:2) Tertiary control for ventilation Once an appropriate setting is found (usually left to the default), it is rarely adjusted

24. Where do you start? Bias flow Adjusted with a knob, monitored with a Thorpe tube When HFOV is being initiated, this is the first parameter to be set If the flow is insufficient, then desired mPaw cannot be reached If the flow is too high, the negative force of the active exhalation may be negated

25. Where do you start? Oscillatory function The button is either on or off FiO2 Controlled independent of the ventilator with the use of a blender Pre-use check Patient circuit calibration Must be completed with every circuit change Ventilator performance check

26. Where do you start? Set up heated humidifier Attach a closed-system suction catheter Suctioning required at least every 12 hrs to prevent occlusion of the ETT Patient/family education Complications: pneumothorax, hemodynamic compromise, mucus plugging, anesthesia-related, possible exposure to infectious droplets Noise Chest wiggle

27. How is HFOV implemented? Recruitment maneuvers should be performed upon initiation of HFOV Also, after patient circuit disconnection, suctioning, or when SpO2 decreases >5% Amount of pressure and timing is facility specific Oscillatory function should be paused during maneuver If a permissible cuff leak is being used to control PaCO2, the cuff should be reinflated for the duration of the maneuver Contraindications: pneumothorax, unstable hemodynamics

28. How is HFOV implemented? Initial settings: Bias flow is to be set between 25-40 LPM mPaw is to be set 5 cmH2O higher than CMV mPaw If hemodynamically unstable, mPaw may be set at 2-3 cmH2O higher than CMV mPaw Set the power to 4.0 and increase until adequate chest wiggle is achieved Adequate chest wiggle can be determined by placing a tongue depressor on the patient’s mid-thigh and increase the power until the patient visibly shakes from shoulders to mid-thigh

29. How is HFOV implemented? Initial settings: Frequency should be set in the range of 5-6 Hz Ti% should be left to the default FiO2 set to 100%

30. How is HFOV implemented? Confirmation of appropriate settings can be achieved by chest x-ray and ABG, both to be done within 1 hr of transition Visualization that the 9th posterior rib is above the diaphragm shows adequate lung expansion and appropriate mPaw setting The oscillatory function should not be paused during the chest x-ray Chest x-rays should be reordered whenever there is a suspected change in lung volume or disease process

31. How is HFOV implemented? Confirmation of appropriate settings can be achieved by chest x-ray and ABG, both to be done within 1 hr of transition If ABG shows elevated PaO2: FiO2 should be weaned in 5% increments, until <60% If lung volume remains the same, it is safe to wean to 40% If lungs are near hyperinflation, mPaw should be decreased by 1-2 cmH2O while also weaning FiO2 to 40% After FiO2 has been weaned to 40%, mPaw should be decreased by 1-2 cmH2o every 4-6 hrs

32. How is HFOV implemented? If ABG shows a PaO2 that is lower than acceptable: Increase FiO2 to 100% Increase mPaw by 3-5 cmH20 every 20-30 minutes until oxygenation improves Lung volume should be rechecked via chest x-ray If ARB shows a pH that is higher than acceptable: Decrease the power, while maintaining adequate chest wiggle If not resolved, then frequency should be increased If not resolved, then decrease Ti%, to 33%

33. How is HFOV implemented? If ARB shows a pH that is lower than acceptable: Increase the power, while maintaining adequate chest wiggle If not resolved, then frequency should be decreased Minimum of 3Hz If not resolved, generate cuff leak Slowly deflate cuff until mPaw decreases by 5 cmH2O Then increase bias flow until previous mPaw value returns If not resolved, then increase Ti%, to 50% Permissive hypercapnia: as long as the patient’s pH remains >7.20, an elevated PaCO2 is not corrected

34. How is HFOV implemented? General patient assessment every 2 hrs Chest wiggle factor Watch for changes in vibration and symmetry Auscultation Normal BS will not be heard, but changes within the lungs can alter the sound of the pistons as heard through the lungs Perfusion status via capillary refill VS

35. Weaning Can be considered after the underlying disease process has resolved, and the patient tolerates the following: mPaw 22-24 cmH20 SpO2 >88%, with FiO2 ≤ 40% When back on CMV, a mode that is also lung protective (PVC, PRVC) is beneficial mPaw on CMV should be the same as on HFOV Vt should remain low-normal (6-10 ml/kg IBW) Rate, PEEP, FiO2 determined by ABG values

36. Summary HFOV appears to be a safe alternative therapy for patients who are failing CMV Main benefit is improved oxygenation This has been found not to ensure patient survival Early intervention improves outcome

37. Thank you for your time Questions?