More receiving HFOV required vasopressors or other vasoactive drugs (91% vs. 84%, p=0.01) and for longer: 5 days vs. 3 days (p=0.01). By contrast, Duncan et al (OSCAR trial) found an identical ~41% 30-day mortality in both groups. After covariate adjustment, the odds ratio for survival in the conventional low-tidal volume group was 1.03 (p=0.87).
Full Answer
What is high frequency oscillatory ventilation?
High-frequency oscillatory ventilation (HFOV) is a rescue maneuver for failed conventional mechanical ventilation. It utilizes the Taylor augmented dispersion of gases through a simple circuit in which bias flow delivers small tidal volumes for patients with acute respiratory distress syndrome (ARDS) and other medical conditions [1–4].
Can high frequency oscillatory ventilation be used to rescue ARDS patients?
Salahuddin N, Al Saidi H, Kherallah M, Solaiman O, Maghrabi K. High frequency oscillatory ventilation may not rescue ARDS patients: An observational study. Crit Care Shock2013;16(2): 58–64. [Google Scholar] 59. Sud S, Sud M, Friedrich JO, et al. .
Does high-frequency oscillatory ventilation prevent chronic lung disease of prematurity?
High-frequency oscillatory ventilation for the prevention of chronic lung disease of prematurity. N Engl J Med2002;347(9): 633–42. doi: 10.1056/NEJMoa020432.
What are the main applications of high-frequency oxygen flow ventilation during surgery?
This report emphasized the main applications of HFOV during surgery: anesthetic care for neonates already receiving HFOV, minimizing lung movement and interference with the surgical field, and application when altered respiratory compliance led to ineffective intraoperative oxygenation/ventilation.
When do you use high frequency oscillatory ventilation?
High-frequency oscillatory ventilation (HFOV) is a lung-protective strategy that can be utilized in the full spectrum of patient populations ranging from neonatal to adults with acute lung injury. HFOV is often utilized as a rescue strategy when conventional mechanical ventilation (CV) has failed.
How do you wean off HFOV?
Weaning First wean FiO2 until ≤ 0.60 unless hyperinflated. ... Once FiO2 ≤ 0.60 or hyperinflated, decrease MAP by 1 cm Q4-8h; if OXYGENATION is lost during weaning then increase MAP by 2-4 cm to restore lung volumes and begin weaning again, but proceed more slowly with decreases in MAP.More items...
Is high frequency oscillatory ventilation invasive?
Although HFV has been applied in many neonatal intensive care units, nasal high-frequency oscillatory ventilation (nHFOV) is a relatively new non-invasive modality, and evidence for its use is limited.
What are the cases that high frequency ventilation is commonly used for and why?
High-frequency pressure ventilation (HFPV) is a time-cycled, pressure-limited mode of ventilation that delivers subphysiologic tidal volumes at rates as high as 500 breaths/min. HFPV has been used in burn units, specifically for patients with inhalation lung injury, and for salvage therapy in patients with severe ARDS.
What is the difference between an oscillator and ventilator?
High‐frequency oscillation (HFO) ventilation differs from conventional ventilation in that very small breaths are delivered very rapidly (180 to 900 breaths per minute). HFO helps with the opening of collapsed lung tissue by providing constant positive pressure in a person's airway.
What is an oscillating ventilator?
High frequency oscillatory ventilation (HFOV) is a type of mechanical ventilation that uses a constant distending pressure (mean airway pressure [MAP]) with pressure variations oscillating around the MAP at very high rates (up to 900 cycles per minute). This creates small tidal volumes, often less than the dead space.
What is an oscillator in the NICU?
Conclusion. When working with neonatal lungs, the oscillator is a softer mode of lung ventilation, which can reduce ventilator-induced lung injury. The small tidal volumes the oscillator produces can reduce volutrauma.
What is an oscillator used for in hospitals?
The Oscillator controls both inspiratory and expiratory phases and is thus capable of ventilating both normal and sick lungs. It has been used to treat a wide range of acute and chronic conditions such as BPD in babies and ARDS in adults.
What is high frequency chest wall oscillation?
High-frequency chest wall oscillation involves an inflatable vest that is attached to a machine. The machine mechanically performs chest physical therapy by vibrating at a high frequency. The vest vibrates the chest to loosen and thin mucus. In CF, the mucus is often thick and sticky. .
Which of the following is an indication for high frequency jet ventilation?
Some of the indications for nonventilated lung HFJV include BPF, surgery of the major airways, and acute respiratory distress syndrome (ARDS). HFJV utilizes delivery of oxygen using small VT (<2 mL/kg) at very fast rates (100 to 400 breaths/minute).
How does high frequency jet ventilation work?
High frequency oscillatory ventilation (HFOV) uses a reciprocating diaphragm to deliver respiratory rates in the range of 3 to 15 Hz (up to 900 breaths per minute) through a standard endotracheal tube. This rate is so fast that the airway pressure merely oscillates around a constant mean airway pressure.
Which oscillator is used for high frequency oscillation?
High-frequency oscillatory ventilation utilizes oscillations generated by a piston pump or a diaphragm oscillator driven by a motor. It produces a sinusoidal or somewhat erratic pressure waveform that gives the expiratory phase its unique active characteristic.
What is high frequency ventilation?
High-frequency oscillatory ventilation utilizes oscillations generated by a piston pump or a diaphragm oscillator driven by a motor. It produces a sinusoidal or somewhat erratic pressure waveform that gives the expiratory phase its unique active characteristic. This component is created by the backward movement of the diaphragm or piston of the oscillator. A constant distending airway pressure is applied, over which small tidal volumes are superimposed at a high respiratory frequency.
What frequency should HFOV be used for?
In most HFOV trials and clinical reports, rates of 10– 15 Hz were used. This range of frequency covers the majority of clinical situations in neonates. Those rates are near the resonant frequency of the infant lung. 6 Bohn has recommended a fixed frequency of 15 Hz. 7 The frequency of the oscillation influences carbon dioxide removal in the direction opposite that which happens during CMV. A decrease in frequency from 15 Hz to 12 Hz is responsible for a decrease in arterial partial pressure of carbon dioxide (Paco 2 ). Decreasing the frequency increases tidal volume. Below 12 Hz, a decrease in arterial partial pressure of oxygen (Pao 2) is also observed. 4
How does HFOV affect cardiac output?
The interaction between HFOV and cardiovascular function is largely determined by the level of P mean and respiratory compliance but is independent of frequency rates. If a high P mean is used, lung distension might occur, leading to impaired venous return, cardiac function, and reduced cerebral perfusion. 12,13 If P mean is carefully reduced when arterial oxygenation improves, HFOV can be achieved without depressing cardiovascular dynamics more than CMV. 14 Moreover, severe paroxysmal sinus bradycardia has been reported and was related to overdistension of alveoli as compliance was improving. 15
Why is HFOV used during surgery?
The global clinical impression is that the use of HFOV during neonatal surgery improves surgical comfort and respiratory status compared with conventional ventilation. As neonatal care improves, anesthesiologists will be faced with an increasing number of high-risk neonates and therefore must be familiar with this mode of ventilation. The history of HFOV clinical trials shows the difficulty in evaluating this technique despite a large population. 34 Notwithstanding the absence of randomized controlled trials, HFOV seems to be a useful adjunct for providing preoperative respiratory support. Nevertheless, studies are necessary to better determine which infants may benefit most from HFOV during surgery.
When was HFOV first used?
The first successful use of HFOV was reported by Marchak et al. 16 in 1981 in eight neonates with neonatal respiratory distress syndrome. Since that time, many clinical trials have been performed and extensively reviewed in the Cochrane database. 17,18 These clinical trials varied widely in design, neonatal care, and ventilation strategies, explaining conflicting results.
How does tidal volume affect paco?
There is a close relation between pressure amplitude and tidal volume. Tidal volume depends on the volume displaced by the piston or the diaphragm, the resistance of the airway, the compliance of the ventilator circuit, and the patient’s lung mechanics. Therefore, the efficiency of oscillation is ensured by the visualization of chest vibrations. Changes in pressure amplitude are used to control ventilation and thus Paco 2. Increasing pressure amplitude and, thus, tidal volume improves carbon dioxide elimination. To avoid hypocapnia, the level of peak-to-peak pressure may be adjusted clinically to the point that it just produces visible chest vibrations and to that which produces the desired Paco 2 or transcutaneous carbon dioxide (Tcco 2) values.
What are the variables of an oscillator?
Oscillator variables adjusted by the operators are frequency, mean airway pressure (P mean ), pressure amplitude or peak-to-peak pressure, fraction of inspired oxygen (Fio 2 ), and, for some oscillators, percentage of inspiratory time. 4
What frequency to use for air leak?
Use a FREQUENCY of 12-15 Hz in order to minimize both total I.T. and TV in order to heal the airleak.
How often does Paco 2 decrease frequency?
6) Hypercarbia - If PaCO 2 still remains elevated at high POWER setting (>8.0), decrease FREQUENCY by 2 Hz every 15-20 min until maximum tidal volume is reached (3-4 Hz at a POWER of 10.0). The lower frequency leads to a longer I.T. leading to a larger tidal volume of gas being displaced towards the infant. This increased TV leads to improved alveolar ventilation (HFOV, Ve ≈ (TV) 2 f).
How to minimize volutrauma?
The goal is to minimize volutrauma, barotrauma, atelectatrauma, biotrauma and oxygen toxicity. Use minimum power/amplitude to keep PaCO 2 adequate (e.g., 50-70 mmHg). Increase MAP as necessary to keep FiO 2 <0.50 if possible. Use I.T. of 33%. Use frequency of 10-15 Hz. Use lower frequencies (6-10 Hz) if having difficulty with oxygenation or use the higher frequencies if having problems with hypocarbia or PIE.
Why is it important to normalize Paco 2?
5)Warning - It is extremely important to normalize PaCO 2 rapidly by weaning Power in order to avoid volutrauma from excessive tidal volumes.Check ABG's frequently (Q15-20 min) and decrease POWER accordingly until PaCO 2 > 35. A PaCO 2 < 35 correlates with an increased risk of pneumothorax. Thus to minimize the risk of volutrauma, it is important to use the least amount of TV (POWER or AMPLITUDE) possible to achieve ventilation.
How to give surfactant replacement therapy?
Give surfactant replacement therapy using manual bagging. Start with frequency of 15 Hz, I.T. of 33%. Use MAP of 8-10 cm or 2 cm above MAP on CMV. Wean FiO 2 until <0.50 then MAP as tolerated to avoid over-inflation. Wean power/amplitude to keep PaCO 2 45-60 mmHg. Follow blood gases Q30-60 min after SRT until stable and wean appropriately to avoid hypocarbia.
What does delta P mean in HFOV?
Many HFOV centers have you order amplitude or delta P (ĢP) to regulate ventilation instead of power. We have decided that the Power setting is a more reliable way of adjusting this ventilator and thus we order changes in power in order to regulate ventilation.
What is the best frequency for a baby?
Set initially at 10 Hz (600 BPM) for term infants and 15 Hz (900 BPM) for premature infants (< 2.5 kg). For children between 6-10 kg, use 8 Hz, and for children > 10 kg, use 6 Hz for an initial setting.
What to do after initial HFOV settings?
After initial HFOV settings are established, perform an initial recruitment maneuver and oxygen/mPaw adjustment as per protocol (see Fessler et al, 2007)
What is HFOV in medical terms?
High Frequency Os cillation Ventilation (HFOV) is an unconventional form of mechanical ventilation that maintains lung recruitment, avoids overdistention, and does not rely on bulk flow for oxygenation and ventilation
What is coaxial flow pattern?
Coaxial flow patterns = net flow through the centre of the airway on way down, then on outside of airway on way up
Is HFOV good for ARDS?
HFOV found to cause harm or have no benefit in the 2 best RCTs in adult ARDS patients. previous studies compared HFOV to outdated ventilation strategies. Unclear if lack of benefit is due HFOV per se or the protocols used, patient selection or need for increased sedation and paralysis.
Does HFOV help with respiratory distress?
no benefit from HFOV in respiratory distress of premature infants and increased adverse effects (pneumoperitoneum, IVH, periventrivular leukomalacia)
Is HFOV a routine part of ARDS?
HFOV should not be a routine part of the management of ARDS patients, but is still an option for refractory ARDS patients ( in the absence of EC MO) Cochrance Systematic Review ( published prior to OSCAR and OSCILLATE) meta- analysis in ALI and ARDS patients. 8 RCTs, n= 419 patients.
When was HFOV approved?
In 2001, the Food and Drug Administration approved HFOV devices for use in adult patients with acute respiratory distress syndrome (ARDS) who failed conventional mechanical ventilation ( CMV ).
When was HFOV first used?
HFOV was first described in 1972 and was used to improve oxygenation in neonates with severe respiratory distress syndrome. This was gradually expanded into larger, more mature pediatric patients with severe respiratory failure. In 2001, the Food and Drug Administration approved HFOV devices for use in adult patients with acute respiratory distress syndrome (ARDS) who failed conventional mechanical ventilation ( CMV ).
What color is oxygen in HFOV?
On all patients placed on HFOV, it is crucial that oxygen is flowing to the patient. By convention, in the United States oxygen tubing and cylinders are color-coded green. Pressurized air is color-coded yellow, and contains only 20.9% oxygen, the same as room air. Most HFOV ventilators display the amplitude and frequency. While an unexplained rise in amplitude can suggest that the endotracheal tube is becoming obstructed, a sudden decrease in amplitude can suggest pneumothorax. Examining the ventilator tubing can sometimes reveal secretions or hemoptysis. When examining the patient, a decrease in the patient’s chest wiggle can suggest pneumothorax, and a prompt chest x-ray should be performed. Although suctioning and bronchoscopy can cause derecruitment, they can be very important in managing the patient on HFOV. Care should be taken to minimize the duration of suctioning and bronchoscopy, and recruitment maneuvers might be considered following any interruption in HFOV.
What is HFOV in CMV?
HFOV can be considered to have separated oxygenation and ventilation into 2 separate mechanisms. Similar to CMV when the respiratory frequency exceeds the time for intrinsic exhalation phase, HFOV delivers breaths that can lead to developing auto–positive end-expiratory pressure (auto-PEEP).
How does HFOV work?
HFOV is based on several features of nonlaminar flow of gas into and out of a circuit. High-pressure gas flows down the center of the airway , displacing lower pressure gas via coaxial flow and bulk flow. Between cycles and in distal airways, gases mix uniformly so that delivered, oxygen-rich gas saturates available alveoli to maximize the chances of diffusion of oxygen into the bloodstream. This mixing is called pendelluft and essentially accounts for dead space ventilation of any kind, but is especially useful in HFOV. “Exhaled” gases move by previously mentioned bulk and coaxial flows toward the negative pressure generated by the high-velocity “breaths” where they ultimately exit the endotracheal tube into the exhalation circuit. HFOV can be considered to have separated oxygenation and ventilation into 2 separate mechanisms.
What is the determinant of oxygenation during HFOV?
The main determinant of oxygenation during HFOV is the mPaw which is generally initiated at approximately 5 cm H 2 O greater than the mPaw noted during conventional ventilation.
What are the mechanisms of gas exchange during HFOV?
Other mechanisms of gas exchange during HFOV include cardiogenic mixing where the contracting heart causes mechanical agitation of gas, especially in lung units surrounding the heart, and molecular diffusion near the alveolar-capillary interface. +.
Initial Settings
- Frequency
Initial settings: 10 Hz(600 BPM) for term infants ( > 2.5 kg) 12 Hz(720 BPM) for premature infants (1.5 - ≤ 2.5 kg) 14 Hz(840 BPM) for preterm infants ( 1.0 - < 1.5 kg) 15 Hz(900 BPM) for preterm infants < 1.0 kg 8 Hz(480 BPM) for children between 6-10 kg 6 Hz(360 BPM) for children > 10 k… - Inspiratory time
Set initially at 33%
Management Strategies
- The SensorMedics HFOV is used for premature infants, term infants or young children with respiratory failure not responsive to conventional ventilation or first intention therapy for premature infants with RDS.
Weaning
- Oxygenation
Once oxygenation is adequate and the patient is ready to be weaned follow these steps: 1) First wean FiO2until ≤ 0.60 unless hyperinflated. During active changes in compliance (e.g., surfactant replacement, aggressive diuresis, …) may need to follow chest radiographs as frequently as ever… - Ventilation
Reduce POWER by 0.2-0.3 units per change (amplitude/delta P 2-3 cm H2O) whenever PaCO2 decreases below threshold (e.g., < 45 mm Hg) until minimal POWER/amplitude/delta P is reached (power <1.5-2.0, delta P < 15-20 cm H2O) depending on the size of the patient. If frequency is bel…
Potential Complications Associated with HFOV
- Hyperinflation
Can lead to increased pulmonary vascular resistance and air leaks, decrease MAP - Secretions
Increase suctioning (inline suctioning is optimal to minimize loss of lung recruitment