Susan P Pilbeam, MS, RRT, FAARC

Consultant, Maquet, Inc

Outline

� History of helium and industrial uses

� Properties of Helium

� Availability of helium

� Helium as a thermal conductor in the MRI suite and in respiratory care equipment.

� Respiratory application of heliox

� Heliox administration during mechanical ventilation

� First detected in 1868 by French astronomer Jules Janssen

� Noted as an unknown yellow spectral line in sunlight during a solar eclipse.

� It was named helios, from the Greek word for sun.

� Helium was isolated in 1895 by the British Chemist Sir William Ramsey.

Reference: Wikipedia and Pilbeam SP & Cairo JM: Mechanical Ventilation -Physiological and Clinical Application, 4ed, St. Louis, Mosby/Elsevier

� Alvin Barach (1934) confirmed the inertness of helium.

� Exposed mice to 79:21 mixture for two months.

� No deleterious side effects.

� Barach found that labored breathing with an 80:20 helium-oxygen mixture (heliox) reduced airway and intra-abdominal pressure approximately 50%.

� He subsequently used a Heliox mixture on 4 adult patients with asthma and two infants with upper airway obstruction.

� Followed the explosion of the Hindenburg in (hydrogen filled), Congress began to regulate the sale of gases (1937).

� Helium used in PFT labs to determine functional residual capacity (FRC).

� Heliox 1980’s resurfaced when the fatality rates from severe asthma started to increase. (Rodrigo, Chest, 123, 2003)

� Arc welding - Helium creates an inert atmosphere around the flame.

� NASA uses it to pressurize space shuttle fuel tanks and look for leaks

� Helium is used in cryogenics (very low temperatures)

� Cryogenics is its largest single use, absorbing about a quarter of production.

� About 1/3rd of all the world’s helium supply is found within a 250-mile radius of Amarillo, TX. (Ellis, USA Today, 9/23/2011)

� 32 billion cubic foot reserved in underground storage area of porous rock in Cliffside, TX near Amarillo.

� The US government is now selling the stockpile.

� Estimated that Cliffside, TX will be empty in the next 10-25 years.

� “Earth will be virtually helium free by the end of the 21st century.” (Ellis, USA Today, 9/23/11)

� The cost of helium.

� Helium has the lowest boiling point (-458 °F) and melting point (– 452° F) of any element.

� Helium exists only as a gas except in extreme conditions.

� On earth it is primarily found in natural gas fields and is distilled from natural gas.

� Except for hydrogen, helium is the most abundant element in the universe, but rare on earth

� It is odorless, colorless, tasteless, nontoxic inert element.

� It will NOT react with human tissue or with any pharmaceutical agents.

� It is the second lowest density gas of any known gas, next to hydrogen and is three times less dense than air.

For a given pressure difference, laminar gas flow provides a greater flow rate compared to turbulent gas flow, making it more efficient.

A.

B.

� In normal individuals during normal quiet breathing-

� Turbulent flow affects the larynx and trachea and the first and second generation bronchi (main stem and lobar bronchi)

� Turbulent flow – the driving pressure is proportional to the gas density and flow.

� Helium is more effective in turbulent flow conditions.

� Heliox reduces areas of extreme turbulence to less turbulent, and

� Areas of turbulence to more laminar flow.

� This improves the efficiency of gas flow through narrow airways, such as with airway obstruction.

Gentile MA: RC 2011 56:1341

� Thermal conductivity is the property of material’s ability to conduct heat.

� Helium is an excellent thermal conductor

� Some countries, like China, uses helium to cool nuclear reactors

� The main commercial application of cooling is in magnetic resonance imagingmagnetic resonance imagingmagnetic resonance imagingmagnetic resonance imaging (MRIMRIMRIMRI) scanners.

� Liquid helium is used to cool the superconducting coils in the magnet.

� Some of the helium is gradually evaporated.

� There is a helium condenser that can re-condense helium vapor to liquid helium reducing the loss of the gas.

� The condenser reduces the need for refilling the "cryogens.“

Janitor’s Equipment Quenching the Magnet

� The word "quench" describes the process of reducing the strong magnetic field by turning the liquid helium into gaseous helium (by warming it a bit) and venting this to the atmosphere.

https://www.facebook.com/photo.php?fbid=1057007116172&set=o.119488190267&type=1&theater

� If the magnet quenches for any reason, then a full refill of liquid helium is required.

� Between 500 - 750 liters of liquid helium

� “The cost is about $15 per liter, so it costs between $7500 and $11,250 for us to fill one magnet.” (Dr. Pooley, Mayo Clinic; Jacksonville, FL.)

� Less than nitric oxide, but more than oxygen.

� Florida – Praxair

� Large cylinder $55 to $185

� Costs are rising because of

reduced availability.

� Administering a heliox mixture (70:30) better preserves lung function than ventilation with pure oxygen in horses

Staffiere F et al: Equine Vet J, 2009 41:747.

� Examples of heat use in Respiratory

Care equipment:◦ Heated wire circuits

◦ Heated humidifiers

◦ Flow/volume monitors that use heat

� Heliox has a high thermal conductivity.

� Heliox carries heat away from the source quickly.

� Heated humidifiers – heliox conducts heat away from the humidifier as it passes to the patient.

� This cooling effect may also affect temperature alarms on the humidifier.

� Loss of heat may predispose to cooling in patients, particularly neonates and infants. (Chowdhury M, et al: Ventilation,2006, 2(5) 194.)

� It is important that heliox is well heated and humidified.

� Not uncommon for the expiratory limb of the patient circuit to be unheated.

� With heliox there may be considerable condensate in the expiratory line.

� Water traps

(Chowdhury MMM Reus E., Brown MK, et al: Ventilation,2006, 2(5) 194.)

Heated Sensors Hot Wire Anemometer

� Hot wire anemometers

� Hot wire pneumotachometer

� Heated thermistor beads.

� Gas passes over the heated bead or wire and cools the sensor.

(Cairo JM, et al: Mosby’s RC Equipment 8th edit.)

�Helium cools faster than air or oxygen.�Cooling changes the resistance of the sensor in proportion to the gas flow over the heated element.

�Amount of power output to maintain the temperature of the element is related to the velocity of the gas flow.

�Volume and flow measurements will be different with heliox than with air/oxygen.

• Ventilators using heated expiratory sensors.

• Examples:

� Drager E-4 and Evita XL

� Puritan Bennett 7200 and 840

◦ Differences in Vtset and Vtdel.

◦ Users need to be aware of the affect of heliox on the ventilator they are using.

Brown M, et al (2005, RC 50:354) and Gluck EH (Chest 1990, 98:693)

◦ Drager E-4: “The ventilator gives a high priority alarm, which cannot be silenced, but requires inactivation of the inspiratory flow monitor. The flow sensor must be removed to accomplish ventilation with heliox.”

◦ (Tassaux D, et al, AJRCCM 160:22, 1999)

◦ PB 840 will not cycle.

◦ Will alert to operator that low-density gas connected.

Brown M, et al (2005, RC 50:354) and Gluck EH (Chest 1990, 98:693)

� Because of its low atomic weight, helium diffuses very rapidly.

� Helium’s diffusion coefficient allows CO2 to diffuse more rapidly through heliox than through air or oxygen. (Hess, et al; RC 51:608, 2005)

� A problem in helium use and storage is preventing leakage.

� Endotracheal tube leaks – cuffed or uncuffed

� During NIV – select best mask fit possible.

� Be sure the ventilator you are using does not have a venting hole in its delivery system.

� “In ventilators such as the Evita 4, which has leak compensation, the expiratory flow sensor malfunctions with heliox, and this is interpreted as a gas leak in the circuit, which triggers an increase in inspiratory-valve opening, which further increases the delivered Vt.”

� This problem was alleviated by inactivating the leak compensation mechanism.

Venkataraman, ST: Heliox during mechanical ventilation, Respir Care 51(6), June, 2006, pg 632-639.

�Upper Airway

Obstruction

�Lower Airway

Obstruction

Clinical Application of Heliox in Patients

� Postextubation stridor

� Asthma

� To try to avoid intubation in patients with acute exacerbation of asthma.

� Tracheobronchitis

� Viral laryngitis

� Laryngeotracheal bronchitis

� Bronchiolitis

� Tumors (laryngeal or mediastinal)

� Foreign body aspiration

� Vocal cord paralysis

� COPD

� May relieve discomfort and minimize patient effort while waiting for other treatment effectiveness.

� Heliox reduces work of breathing

� In some cases heliox improves clearance of carbon dioxide.

� Transairway (Pta) is the pressure difference between the mouth (Paw) and the alveoli (Palv)

� Pta = Paw – Palv).

� Pta is pressure

associated with airway

resistance.

� “At a given flow, the transairway pressure will be lower with heliox than with air or air-oxygen.”(Venkataraman ST, Respir Care, 51:632, 2006)

� When Pta is constant, flow through the airways is higher with Heliox, compared to air or oxygen.Hess et al, RC 51(6), 2006; Wigmore et al, Crit Care & Resusc 8:64, 2006

� A total of 59 patients with acute asthma treated in E.D.

� Nebulized bronchodilator using oxygen or heliox and forward leaning posture versus erect posture.

� Heliox with nebulized bronchodilator and forward leaning posture improved bronchodilator efficacy in patients with severe acute asthma.

� Primary outcome % improvement in FEV1 and PEF. Secondary: HR, SpO2 and respiratory rate.

Brandão DC, et al: Respir Care 2011 56:947.

From Ritz R: Respir Care 44:686, 1999.

Brandao DC, et al: RC 56:947, 2011

� Heliox 60:40 in 13 mechanically ventilated, sedated and paralyzed infants with RSV (respiratory syncytial virus) induced respiratory failure.

� Heliox significantly reduced respiratory system resistance.

� This was not accompanied by an improved CO2 elimination.

Kneyber MCJ, et al Crit Care 2009 13:R71

� Two systematic reviews of the literature in 2003

� Heliox mild-to-moderate benefits with acute asthma within one hour.

� Improvement more pronounced in severe cases.

� Existing evidence does not support heliox administration in the E.D. in patients with moderate-to-severe asthma.

� Insufficient data on whether heliox can avert tracheal intubation or change duration of intubation, ICU or hospital stays or mortality.

� Small studies based on between-group comparisons. Interpret with caution.

Rodrigo GJ, et al, Chest 123:891, 2003Ho AMH, et al, Chest 123:882, 2003

� Reduce the work of breath immediately until the obstruction can be alleviated.

� Heliox does not cure the cause of airway obstruction.

� There are no known contraindications for the use of Heliox. (Hess, et al, RC 51:608, 2005)

Hanna S. Sahhar, MD

Noninvasive and Invasive

� Total of 204 patients with known or suspected COPD and acute dyspnea (PaCO2 >45; pH <7.35 and rate >25/min)

� NIV with and without helium via face mask

� Duration of NIV, length of stay and 28-day mortality were similar.

� No statistically superiority of using helium during NIV or to reduce intubation rates in patients with acute exacerbation of COPD

Maggiore SM, et al: Crit Care Med, 2010 38:145

Potential Effects on Invasively Ventilated Patients

�Reduces PIP in volume ventilation�Increases CO2 elimination & improves gas exchange�Reduced Auto-PEEP�Altered volume delivery (‘set’ versus ‘delivered’)�Increased flows �Reduced rate

� VC, the higher the helium percent, the lower will be the PIP, while achieving the same Vt.

� PC, the Vt will increase for the same pressure as the helium percent increases.

� Mean PaCO2 may decrease and pH improve in patients with asthma (Venkataraman SK: Respir Care 51(6), 2006.)

� If the same pressure is used ventilating with heliox or air/O2, the volume and pressure in the alveoli will be higher with heliox.

� The effort to move a volume of gas to the alveolus is lower than 1/3rd when using helium rather than nitrogen.

Gentile M: Respir Care 2011 56:1341

� Reduction in intrinsic PEEP

� Reduction of inspiratory and expiratory resistance through the airways

� Enhanced flow

(Venkataraman SK: Respir Care 51(6), 2006.)

� Use of heliox has been basically off-label until ventilators with 510K approval for heliox were made available.

� On earlier generation ventilators during volume ventilation, delivered Vt is greater than set. Examples: VeolarFT, Galileo, Evita 2, Evita 4 and Servo 900C

(Venkataraman SK: Respir Care 51(6), 2006, Pilbeam et al: Mech Vent., 2006 Mosby.)

� With 7200 Vt was smaller than set

� PB 840: Will not cycle at all. Heliox cannot be used.

� Servo 300 –Function is not affected by heliox. A linear relationship exists between delivered Vt and set Vt.

� Those with FDA approved heliox delivery systems.

� CareFusion Avea – earliest available

� Servo-I Hamilton

ISI_0060_XX

� Bird VIP, Bird VIP Gold, Servo 300 and Servo 900C (Berkenbosch, et al, 2003 study)

� Servo 300 was the most efficient in its helium consumption.

� The Bird VIP was 8 times higher during volume ventilation and 17 times higher during pressure ventilation.

� Servo 300 delivered Vt was slightly smaller than Vt set

Heliox with 4 Infant/Pediatric Ventilators (Venkataraman SK: Respir Care 51(6), 2006.)

Bench Study: Servo-i saves 893 liters of helium per hour or $203 per day.

Equal to four tanks a day for Avea and 5/8th of a tank for the Servo-i.)

Daria Donelly, Brian K. Walsh; RC, Respiratory Care, Open forum, 2009

MX-0750

Heliox Utilization

0

50

100

150

200

250

300

350

400

450

500

PS

I

Avea 1

Avea 2

Servo-I 1

Servo-I 2

� Conclusion: Little difference in the rate of heliox consumption in two of three ventilators. The third (Avea) much higher consumption rate (66.8%) Due to internal blending system.

� Avea uses is dual proportional solenoids that require a minimum flow to maintain the blended oxygen percentage and cannot shut off during exhalation.

Baxter T, Coulliette H; Respiratory Care, Open Forum 2009

MX-750

� When the ventilator set for pediatric use is powered by heliox, albuterol delivery with an MDI is higher than with an air-oxygen mixture. (Habib DM, Garner SS, et al: Pharmacotherapy 1999; 19(2):143.)

� The higher the heliox concentration, the greater the aerosol delivery.

� The delivery of albuterol is lower when the ventilator circuit is also heated and humidified than when it is dry. (Goode ML, Fink JB, et al: Am J of Respir Crit Care

Med, 2001;163(1):109.)

� Powering a small volume nebulizer with heliox compared to air, decreases the dose. (Hess D; Acosta FL, et al; Chest 1999, 115(1), 184.)

� Hess DR. Heliox and noninvasive positiveHeliox and noninvasive positiveHeliox and noninvasive positiveHeliox and noninvasive positive----pressure pressure pressure pressure ventilation: a role for heliox in exacerbations of chronic ventilation: a role for heliox in exacerbations of chronic ventilation: a role for heliox in exacerbations of chronic ventilation: a role for heliox in exacerbations of chronic obstructive pulmonary disease?.obstructive pulmonary disease?.obstructive pulmonary disease?.obstructive pulmonary disease?. Respiratory Care. 51(6):640-50, 2006

� Venkataraman ST. Heliox during mechanical ventilation. Heliox during mechanical ventilation. Heliox during mechanical ventilation. Heliox during mechanical ventilation. Respiratory Care. 51(6):632-9, 2006

� Tassaux D. Jolliet P. Thouret JM. Roeseler J. Dorne R. Chevrolet JC. Calibration of seven ICU ventilators for Calibration of seven ICU ventilators for Calibration of seven ICU ventilators for Calibration of seven ICU ventilators for mechanical ventilation with heliummechanical ventilation with heliummechanical ventilation with heliummechanical ventilation with helium----oxygen oxygen oxygen oxygen mixtures.mixtures.mixtures.mixtures. American Journal of Respiratory & Critical Care Medicine. 160(1):22-32, 19

� Pizov R. Oppenheim A. Eidelman LA. Weiss YG. Sprung CL. Cotev S. Helium versus oxygen for tracheal gas insufflation Helium versus oxygen for tracheal gas insufflation Helium versus oxygen for tracheal gas insufflation Helium versus oxygen for tracheal gas insufflation during mechanical ventilation.during mechanical ventilation.during mechanical ventilation.during mechanical ventilation. Critical Care Medicine. 26(2):290-5, 1998