High Frequency Ventilation PDF

JERICKSON A. BAYANI,RTRP High frequency ventilation HIGH FREQUENCY VENTILATION  Definition:  rapid rate ventilation with small tidal volume  Goal:  oxygenate and ventilate without ventilator- induced lung injury. HFOV also known as CPAP with a wiggle CPAP sustained...

JERICKSON A. BAYANI,RTRP High frequency ventilation HIGH FREQUENCY VENTILATION  Definition:  rapid rate ventilation with small tidal volume  Goal:  oxygenate and ventilate without ventilator- induced lung injury. HFOV also known as CPAP with a wiggle CPAP sustained lung inflation for alveolar recruitment alveolar ventilation with CPAP-wiggle oscillating pressure waveform at adjustable frequency (Hz) and amplitude (delta P) TYPES OF HIGH FREQUENCY VENTILATION HFJV HFPPV HFOV TYPES OF HIGH FREQUENCY VENTILATION - HFJV High frequency jet ventilation High pressure gas source injects short rapid bursts of gas through a jet catheter, usually incorporated into a special ET tube. Frequency rates vary from 100 to 600 cycles TYPES OF HIGH FREQUENCY VENTILATION HFPP V High frequency ventilation positive pressure Gas deliver to the patient occurs with the use of time cycled or pressure volume limited device Delivers 60-100 /min with a small vt of 3 -5 ml/kg of body weight  HFOV High frequency oscillatory ventilation Requires oscillating device that forces small impulses of gas. 3 types of oscillating devices are used a. Piston b. Diaphragm c. Flow interruptor - Frequency of 60-3600/min HFOV Rationale  HFOV effectively ventilates with intrapulmonary pressure and volume changes that are less than conventional ventilation.  decreased volutrauma  decreased barotrauma Indications  Failure of conventional mechanical ventilation (CMV) and before ventilator-induced lung injury (VILI) occurs  ARDS/ALI (adults) Other neonatal indications  RDS  meconium aspiration  persistent pulmonary hypertension  pulmonary hemorrhage  pulmonary hypoplasia  congenital diaphragmatic hernia Complications  Hypotension due to decreased venous return responds to fluid bolus  Pneumothorax - sudden onset of hypotension - decreased chest wiggle  ETT obstruction- hypercapnia, desaturation -decreased chest wiggle Relative contraindications  increased ICP  obstructive lung disease  HFOV Principle: Pressure curves CMV / HFOV PIP Mean airway PEEP PARAMETERS TO BE SET  Mean airway pressure (MAP)  Amplitude (delta P)  Hertz (Hz)  Bias flow  FiO2  MEAN AIRWAY PRESSURE (MAP) Adjusted in 1-2 cm H2O increments, as determined by: > CXR > Oxygenation- PaO2, SPO2 > FiO2 and MAP used to reduce FiO2  AMPLITUDE/POWER (DELTA P) > SensorMedics- power control adjusts the piston displacement > Adjusted for chest wiggle factor (CWF)  neonates from nipple line to umbilicus  adults from clavicles to mid- thigh. Amplitude/Power (delta P)  Start with a power setting of 2- 4cmH20 to generate the amplitude pressure, increase the power setting to increase amplitude pressure to obtain chest wiggle.  Determines amplitude of oscillation and thus Vt and degree of ventilation  Piston centering DO NOT INCREASE THE POWER SETTING TO EXCEED CHEST WIGGLE BELOW THE UMBILICUS. EXCESSIVE POWER SETTINGS Initially set at: > neonates- 2 cm H2O > adults 6-7 cm H2O  Changed in 1-2 cm increments  Similar to TV adjustment  Alter PCO2 Frequency- Measured in Hertz (Hz) 1 Hz = 1/sec 1 Hz = 60/min  Changing frequency also changes delta P and MAP  Increased frequency ==> increased PaCO2  Initial frequency settings  adults 5-6 Hz  8 HZ 6HZ Frequency controls the time allowed (distance) for the piston to move. Therefore, the lower the frequency , the greater the volume displaced, and the higher the frequency , the smaller the volume displaced. Increased frequency => increased PaCO2 Initial pediatric frequency settings  1000 g 15 Hz  1000-2000 g 12 Hz  2.0-10.0 kg 10 Hz  13-20 kg 8 Hz  21-30 kg 7 Hz  >30 kg 6 Hz  Meconium aspiration 3-6 Hz Bias flow > generates pressure in circuit flushes CO2 > Initial settings (usually not changed)  ƒ10-15 L/min term neonate  ƒ25-40 L/min (adults) too low- MAP not attained > too high- dampens exhalation, increasing PCO2 Monitoring Chest Wiggle factor (CWF)  absent or diminished- airway obstruction  asymmetric- endobronchial intubation  check, especially after patient repositioning Chest radiograph  Initially - should be frequent  8.5-9.0 ribs should be visibleinfants and adults  monitor for expansion, hyperexpansion  Arterial line blood pressure blood gas analysis  SPO2  Endotracheal tube leak Weaning, transition to CMV  Criteria: resolution of pathology, clinical stability, tolerance of procedures  wean FiO2 PCV with optimal TV > APRV > SIMV (Infant Star) Precautionary notes  Competency-based training required for all personnel before they use HFOV  Patients will require sedation, paralysis  Ventilator is not transportable  Pneumatic nebulizer may not be used with HFOV  Limit disconnects, suctioning, bronchoscopies  Consider recruitment maneuvers after disconnects, suctioning. A newborn pre term baby is being ventilated with a high frequency oscillatory ventilator. Ventilator settings and blood gases shown below: MAP 25 pH 7.43 Delta P 2 PaO2 100 Frequency 7 Hz PCO2 44 Bias flow 15 HCO3 23 FiO2 100 SaO2 98% What adjustment do you need to change? A full term infant, diagnosed to have meconium aspiration, is now being ventilated with a high frequency oscillatory ventilator. Initial ventilator settings and blood gases shown below: MAP 16 pH 7.20 Delta P 3 PaO2 80 Frequency 3 Hz PCO2 56 Bias flow 15 HCO3 23 FiO2.40 SaO2 90% What adjustment do you need to make? References  Czervinske, MP, Barnhart SL. Perinatal and Pediatric Respiratory Care, 2nd Ed. Ch. 21. 2003. WB Saunders; St. Louis.  Pilbeam SP, Cairo JM. Mechanical Ventilation: Physiological and Clinical Applications 4th Ed. 2006. pp. 555-561. Mosby-Elsevier, St. Louis.  High-frequency oscillatory ventilation in adult acute respiratory distress syndrome. David M et al. Intensive Care Med Oct 2003;29(10):1656-1665.  In Vitro performance characteristics of high- frequency oscillatory ventilators. Pillow JJ, Wilkinson MH, Neil HL, Ramsden CA. Am J Respir Crit Care Med 2001;164:1019- 1024.  High-Frequency Oscillatory Ventilation for Acute Respiratory Distress Syndrome in Adults. Derdak S et al. Am J Respir Crit Care Med. 2002;166:801-808 THANK YOU