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309 Helium Oxygen Therapy 309 / Page 1 of 12 Description The administration of helium oxygen gas mixtures (heliox) can be an effective, noninvasive, temporizing means of treating various forms of airway obstruction. The benefits of breathing heliox mixtures are due to its lower density and its effect on airflow dynamics. As airway diameter decreases, flow becomes turbulent and the pressure required to generate a given flow increases. By decreasing the density of the inspired gas mixture, the frictional resistance to gas flow is reduced as flow through the airways becomes more laminar. This results in an increase in the velocity of gas flow for a given level of mechanical work performed. The net result is a decrease in the resistive work of breathing and therefore a decrease in total respiratory work. This will result in a reduction in the oxygen cost of breathing and total caloric consumption; a reduction of respiratory muscle fatigue; and possibly the prevention of respiratory failure and the likelihood of invasive interventions such as endotracheal intubation, tracheostomy, mechanical ventilation, and the risks associated with them. Indications The use of heliox therapy is indicated for the treatment of static or slowly resolving, nonprogressive airway obstruction. The successful use of heliox mixtures has been documented in the treatment of obstructive lesions that narrow or compress the upper airway, trachea, larynx, and bronchi; tracheal edema associated with asthma; post extubation upper airway obstruction; and for croup in infants. Heliox administration has also been used to augment mechanical ventilation during bronchoscopy and high frequency ventilation, to wean infants from ventilators following cardiac surgery, and to treat patients with obstructive airways disease (1-13). The use of heliox has been especially useful in treatment of patients in respiratory distress with inoperable obstructive lesions of the upper airways that would not benefit from the insertion of an artificial airway. In these patients heliox administration allows time for chemo and radiation therapy to reduce malignant tumor size thereby avoiding risky operative procedures. Heliox therapy has also been found to be effective in reducing peak airway pressures, CO2 retention and resolution of respiratory acidosis in mechanically ventilated patients suffering from status asthmaticus (18). Ventilated neonates with RDS, airway distension, hyperexpansion, and pulmonary interstitial emphysema, had decreased PIP, mean airway pressure, PaCO2, and improved oxygenation with heliox (19). Physician's Order The administration of heliox must be approved by a physician before therapy is instituted. A written order signed by a physician must be present in the patients chart. House Formula Administer helium-oxygen gas mixture with 80/20 to 50/50 ratios for respiratory distress related to airway obstruction. Titrate the heliox mixture until improvement in clinical signs of respiratory distress occurs. Maintain SpO2 > 92%. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 2 of 12 Delivery System for Mechanical Ventilation Two Cylinders of 80/20 Heliox, two regulators each with dual preset working pressures of 100 psi and 70 psi. A third step down regulator preset to 50 psi. is on the back of the Avea ventilator. The two heliox cylinders and regulators are connected in tandem and set to empty sequentially. Either cylinder can be changed without interrupting heliox gas delivery because of check valves on the regulator manifolds. Both cylinders valves are turned on. The primary cylinder is the one in use and emptying. The working pressure of the primary cylinder is set at 100 psi. The working pressure of the secondary cylinder is set at 70 psi. The primary cylinder will deliver gas until it is near empty. When the pressure in the primary cylinder drops to 70 psi the secondary cylinder will now be in use and begin to empty automatically. When the empty cylinder is changed, the working pressure lever on new cylinder is set to the secondary position, switching the working pressure to 70 psi. The lever on the other cylinder in use is set to the primary position, switching the working pressure to 100 psi. The step down regulator drops the working pressure to 50 psi regardless of which cylinder is in use and emptying. By using this set up, use of gas in the cylinders is maximized, the system switches over to the full cylinder automatically, and the cylinders can be changed without interrupting heliox gas delivery. Equipment Needed • Two 80/20 H-cylinders of heliox gas with dual working pressure regulators, step down regulator and a double H-cylinder cart. (kept in the 4F34). 80/20 E-cylinders of HeliOx gas. (Stored in the 4E tank room beside 4F34.) • Avea Ventilator with preassembled step down regulator and a standard ventilator circuit. The Avea may be used on Adult, Pediatric or Neonates. Heliox can be delivered by the Avea ventilator by simply changing to the “Air Smart Connect” to the Heliox Smart RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 3 of 12 Connect” on the back panel. The Avea identifies the gas input and adjusts to accommodate the change. All volumes (numeric & graphic) are automatically compensated for accurate display. ∗ Warning: When using the Avea ventilator HeliOx usage can be as high as 400psi / hour, requiring frequent tank pressure checks. Air Smart Connect In Parked position while Heliox in use HeliOx Smart Connect In proper position for Heliox delivery Procedure For Mechanical Ventilation 1. Connect the oxygen high pressure hose from the Avea ventilator to a wall oxygen outlet. 2. Connect the air high pressure hose connected to the “Air Smart Connector” to the air docking mechanism found on the back of the ventilator. (make sure air hose is not connected to a 50 psi source) 3. Connect the high pressure hose from the heliox tanks to the 50 psi step-down regulator assembly on the back of ventilator. Connect the “Heliox Smart Connect” (green one) into the Heliox port located on the back of the ventilator to the left of the 02 cell cover. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 4 of 12 4. Turn on both heliox cylinders. The working pressure of primary cylinder preset ~100 psi and the secondary cylinder preset to ~ 70 psi. Note: There are two pressure gauges on each heliox regulator. The one on the left reads the working pressure and the one on the right reads the cylinder pressure. 5. Perform EST (Extended Systems Test) – Follow screen prompts; takes 90 secs. 6. Perform for all new circuits. EST includes: Leak test, test & measures circuit compliance, 7. O2 cell testing. There will be a Heliox icon located in the lower right hand corner of the ventilator screen indicating that Heliox is the connected gas. 8. The Heliox concentration can be changed by increasing or decreasing Fi02. After changing the concentration, the screen will display a message indicating that the Heliox concentration is now changing. A physicians order is necessary for Heliox concentration. Note: If the ventilator analyzer is not calibrated or not working and external oxygen analyzer must be used to verify FiO2 and therefore heliox concentration. 9. Set ventilation parameters and appropriate alarm settings. 10. Connect the patient, and verify the function of the ventilator. 11. Observe patient for clinical signs of improvement. Response to heliox therapy should result in a reduction in peak airway pressures, a reduction in intrinsic PEEP, an increase in delivered and exhaled tidal volume, a decrease in PaCO2 and subsequent improvement in pH. Note: All Volumes (numeric and graphic) are automatically compensated for accurate display Changing The Heliox Cylinders When the pressure in the primary cylinder drops to 70 psi, the secondary cylinder will start to empty. When this happens, reverse the positions on both regulators, make the primary tank the secondary tank by turning the pressure adjusting screw counterclockwise to the secondary position and make the secondary tank the primary by turning the adjusting screw clockwise to the clockwise to the primary position. Make sure you rotate the levers until they hit the mechanical stop. The empty cylinders can be changed without interrupting heliox gas delivery because of check valves on the regulator manifolds. The new full cylinder is now the secondary backup cylinder. Note: Heliox cylinders are stored in 4F34 and out on the loading dock. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 5 of 12 Calculation Of Cylinder Life Heliox cylinder life will depend on the FiO2, the flow rates, and minute ventilation used. The easiest way to calculate cylinder duration is to monitor cylinder pressures and divide the average psi used per hour into the pressure remaining in the cylinder. Usage = 200 psi / hour Cylinder pressure = 1500 psi Cylinder Duration = 1500 psi = 7.5 hrs 200 psi / hr ∗ Warning: When using the Avea ventilator HeliOx usage can be as high as 400psi / hour, requiring RCP to check tank pressure frequently. Procedure for NIV with Respironics Vision BiPAP Therapeutic concentrations of heliox greater than 50% can be delivered during NIV using the Respironics Vision. The concentration of heliox will vary depending on the minute ventilation being delivered and inline nebulization with oxygen. The Vision is used with standard operating procedures (See on Procedure 310 Respironics Vision BiPAP) on 100% oxygen with 20 to 25 L/min of 80/20 heliox bleed-in the the exhalation port. See following chart of heliox delivery during bench test verification. Physician’s Order An order must be written by MD for Pressure Support level and Heliox therapy. Equipment • Respironics Vision BiPAP system. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 6 of 12 • Single limb heated wire circuit. • Respironics exhalation valve. • 80/20 Heliox E-cylinders or H- cylinder of heliox with regulator/flowmeter. • Appropriate fitting mask. Procedure 1. Set-up Vision (See on Procedure 310 Respironics Vision BiPAP). 2. Set FiO2 to 100%. 3. Bleed-in 20 to 25 L/min of 80/20 heliox at the exhalation valve port. 4. Observe patient for clinical signs of improvement. Delivery System For Face Mask The single cylinder of 80/20 Heliox (kept in the 4F34) should be used to administer heliox via face mask or to power a nebulizer for aerosolized medications (see following diagram). Supplemental oxygen is administered via nasal cannula underneath the mask. Procedure For Face Mask Administration 1. Explain procedure and therapeutic goals to patient. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 7 of 12 2. Set up the gas delivery system. 3. Attach Pulse Oximeter to patient for continuous monitoring. 4. Administer oxygen via nasal cannula up to 6 L/min as appropriate. 5. Turn on the heliox to at least 10 -12 LPM 6. Place the mask on the patient and observe for clinical signs of improvement, worsening of respiratory distress, or signs of inadequate oxygen delivery. Note: Patients have reported an instantaneous relief of dyspnea associated with severe airway obstruction and within minutes show clinical signs of improvement. 7. Titrate the heliox and nasal cannula flow rates to optimize clinical effects. Note: To optimize the effects of heliox and reduce the nasal cannula flow to the lowest flow rate possible while maintaining adequate oxygenation. 8. If clinical signs of improvement are observed proceed with humidification of the gas mixture if an extended period of treatment is anticipated. 9. If adverse effects are noted, discontinue treatment and notify the physician. Humidification of Gas Mixture 1. Attach 22mm to 4mm adapter to the inlet of the Fisher Paykel transfer chamber on a HHM set up. 2. Attach oxygen connecting tubing from air flow meter on heliox cylinder to inlet of transfer chamber. 3. Attach aerosol tubing to outlet of transfer chamber. 4. Cut aerosol tubing at third section and connect water trap. 5. Cut tubing from oxygen mask at 12 inches, attach to 22mm to 4mm adapter, universal adapter, and aerosol tubing. 6. Turn on humidifier and adjust temperature to a comfortable level. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 8 of 12 Delivery of Aerosolized Medications A face mask nebulizer should be used on all non-intubated patients. Run the nebulizer from the 80/20 heliox regulator / flow meter. 1. Standard small volume nebulizer – Run the nebulizer with the heliox flow meter set at approximately 10-12 L/min or until adequate aerosol output is produced. 2. Large Volume HEART nebulizer should be used for continuous treatment on nonintubated patients. Run the HEART nebulizer with the air flow meter set at 15 L/min (or until adequate aerosol output is produced) to deliver an aerosol output of approximately 60 ml / hr increase the total fill volume of the nebulizer to 240 ml instead of 200 ml (see Section 205.5). Assessment And Reassessment The patient’s response to therapy should be assessed and reassessed. Patient assessment and reassessment should be performed according to the general RCS policy (see Section IV in the RCS Policy Manual). The need to continue therapy should be reassessed every 24 hours. Specific criteria for assessment and reassessment should include: • Work of breathing – respiratory rate, depth, pattern, degree of dyspnea, and patient complaints of SOB. • Changes in oxygenation and ventilation. • Changes in breath sounds. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy • Changes in Airway resistance. • Patient’s tolerance to therapy. • Patient’s perception of therapy efficacy. • Development of the following complications. 309 / Page 9 of 12 Complications • Progressing airway obstruction. Patients on heliox therapy must be monitored closely for any signs of deterioration. The ICU resident must be notified immediately for any worsening in the patients clinical status. Plans for alternative interventions should be made in advance. • High oxygen requirements. Patients who require increasing levels of oxygen should be removed from heliox therapy when adequate oxygen delivery is no longer possible at therapeutic levels of heliox. (FiO2 > .50). • Hypoxemia. Hypoxia associated with heliox therapy in neonates has been reported and is attributed to worsening of ventilation to perfusion matching (14). Continuous pulse oximetry and continuous inline monitoring of gas mixtures with an oxygen analyzer is therefore mandatory with all patients on heliox therapy. An external oxygen analyzer must be put inline on Servo 900C when internal analyzer is not functioning. • Depletion of helium supply. Since heliox is available in limited quantities, conservation efforts should be made by minimizing flow rates when possible. In non-intubated patients, tracheal helium concentration will be influenced by the patients peak inspiratory flow rate, respiratory rate, the fraction of helium in the delivered gas mixture, the flow rate at which it is delivered, and, the fit of the oxygen mask. Vater et al demonstrated that simulated tracheal helium concentrations of 40% were shown to produce the greatest proportion of increase in flow thru an obstruction in a lung model system at total flow rates of 8 LPM of a 79% helium / 21% oxygen mixture delivered by conventional oxygen masks (15). Delivered flow rates should therefore be kept at a minimum of 8 LPM when using high concentrations of helium. At lower concentrations of delivered helium, higher total flow rates are required to minimize dilution by room air. To conserve helium gas the goal of therapy should be to achieve the best therapeutic effects at the lowest flow rate. Charting Whenever Heliox Therapy Is Instituted An Entry Must Be Made In The Patient's Chart. The Charting format should include the indications and effects of therapy, the heliox mixture used, and a brief summation of events. Charting entries should be made in ICIP or on the patient's cardiopulmonary flow sheet at least every four hours. The charted parameters should include HeO2 for the mode, FiO2, respiratory rate, pulse oximeter saturation, helium cylinder pressure, RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 10 of 12 and ABG's when indicated. In intubated patients, chart the helium and oxygen ratio with all patient-ventilator system checks. Add “freeform ventilator charting” rows to chart heliox ratio and cylinder pressures in ICIP. Charges The patient should be charged for Heliox Therapy in addition to the daily charges for the ventilator, HHM, and nebulizer treatments if used. Discontinuation Heliox therapy should be discontinued per physician's order. All non disposable equipment should be wiped down with a disinfectant solution. The helium cylinders should be returned to the 4F34 storage area. Additional Information The use of heliox has focused on the treatment of obstruction of the upper and large airways where flow is predominantly turbulent and therefore responsive to lowered gas density.(16) There is evidence that suggests heliox may be of benefit in the therapeutic support of patients with obstructive lung disease: conditions traditionally associated with distal or small airway constriction. Barach first introduced heliox as a treatment for airway obstruction secondary to asthma and chronic obstructive lung disease. (7-9) Wood and Barnett (17) demonstrated improved ventilatory response to CO2 and in ventilatory function in 4 of 10 patients with COPD. Swidwa et al (10) showed that in patients with severe COPD, heliox reduced the mechanical work of breathing indicated by a significant reduction in VCO2 associated with: a fall in FRC; a decrease in PaCO2; and an increase in expiratory flow rates without significant changes in breathing pattern. Ishikawa et al (12) showed a reduction in minute ventilation, tidal volume, VO2 and VCO2 in seven subjects with chronic lung disease . Grape et al (11) found that in emphysematous patients there was a marked decrease in total pulmonary resistance during heliox breathing. Gold et al (13) demonstrated improved flow dynamics in asthmatics evaluated by maximum voluntary ventilation and maximal mid-expiratory flow rate measurements during low density gas breathing. These findings indicate that the site of airway obstruction in patients with obstructive lung disease varies within this patient population. Therefore, the use of heliox should not be excluded as a means of therapeutic intervention for severe respiratory distress and impending respiratory failure in patients with obstructive airways disease. In 1990, Kass et al administered heliox therapy to patients in status asthmaticus and found that if there is not a drop in PaCO2 of 15% an hour after initiation, the patient may not respond at all (20). Patient response correlated with duration of status asthmaticus symptoms. All positive responders to heliox therapy presented with an acute exacerbation of symptoms < 24 hours. Thus, heliox should be used as a therapeutic bridge for a 6 to 12 hour interval from patient RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 309 / Page 11 of 12 arrival in the emergency department until corticosteroid impact. Patients suffering from acute status asthmaticus in the emergency room and are on the verge of intubation should be given a trial of heliox therapy. References 1. Rudow, M., Hill, A.B., Thompson, N.W., Helium oxygen mixtures in airway obstruction due to thyroid carcinoma. Can. Anaes. Soc. J. 1986 33:4 498-501. 2. Mizrahi, S., Yaari, Y. Lugassy, G., Cotev, S., Major airway obstruction relieved by helium-oxygen breathing. Crit. Care Med. 1986 14:11 986-987. 3. Curtis, J.L., Mahlmeister, M., Fink, J.B., Laupe, G., Matthay, M.A., Stulberg, M.S., Helium-oxygen gas therapy: use and availability for the emergency treatment of inoperable airway obstruction. Chest 1986 90:3 455-457. 4. Lu, T.S., Ohmura, A., Wong, K.C., Hodges, M.R., Helium-oxygen in treatment of upper airway obstruction. Anesthesiology 1976 45:6 678-680. 5. Boorstein, J.M., Boorstein, S.M., Humphries, G.N., Johnson, C.C., Using helium-oxygen mixtures in the emergency management of acute upper airway obstruction. Annals of Emer. Med. 1989 18:6 688-690. 6. Duncan, P.G., Efficacy of helium-oxygen mixtures in the management of severe viral and post extubation croup. Canad. Anaes. Soc. J. 1979 26:3 206-212. 7. Barach, A.L., Theraputic use of helium. JAMA 1936 107: 1273-1280. 8. Barach,A.L., Use of helium as a new therapeutic gas. Anesth. Analg. 1935 14: 210-215. 9. Barach, A.L., Use of helium in the treatment of asthma and obstructive lesions of the larnyx and trachea. Ann. of Inter. Med. 1935 9: 739-765. 10. Swida, D.M., Montenegro, H.D., Goldman, M.D., Lutchen, K.R., Saidel, G.M., Helium oxygen breathing in severe chronic obstructive pulmonary disease. Chest 1985 87:6 790795. 11. Grape, B., Channin, E., Tyler, J.M., The effect of helium and oxygen mixtures on pulmonary resistence in emphysema. Am. Rev. of Resp. Dis. 1960 81: 823-829. 12. Ishikawa, S., Segal, M.S., Re-appraisal of helium-oxygen therapy on patients with chronic lung disease. Ann. Allerg.1973 31: 536-542. 13. Gold, M., Marks, A., Effects of reduction in air density on dynamic function in obstructive airways disease. Am. Rev. of Resp. Dis. 1964 90: 316-317. 14. Butt, W.W., Koren,G., England, J., Shear, N.H., Whyte, H., Bryan, C.A., Swyer, P.R., Hypoxia associated with helium-oxygen therapy in neonates. J. Pediatrics 1985 106: 474-477. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12 309 Helium Oxygen Therapy 15. Vater, M., Hurt, P.G., Aitkenhead, A.R., Quantitative effects of respired helium and oxygen mixtures on gas flow using conventional oxygen masks. Anesthesia 1983 38: 879-882. 16. Barrnett, T.B., Effect of helium and oxygen mixtures on pulmonary mechanics during airway constriction. J. Appl. Phys. 1967 22: 707-713. 17. Wood, W.B., Barrnett T.B., Effects of helium mixtures on ventilatory response to CO2 in subjects with airway obstruction. Clinical Research 1965 8: 77. 18. Gluck, E. H., Douglas J O, Castriotta, Helium-Oxygen Mixtures in Intubated Patients with Status Asthmaticus and Respiratory Acidosis Chest 1990 693-697. 19. Sola, A., Bisgaard, J.G., Infants with severe lung airway obstruction and their acute response to helium-oxygen mixture. Resp Care 93 38:1238. 20. Kass, E.K., Castriotta, R J, Heliox Therapy in Acute Severe Asthma. Chest 1995 757760. RCS SFGH Reviewed 4/91, 8/92, 9/93, 2/94, 10/07, 11/10 309 / Page 12 of 12 Revised 4/91, 6/98, 3/02, 11/05, 10/7, 11/10, 6/11, 5/12