Vol. 14 •Issue 3 • Page 32
Liquid Oxygen Applications From Hospital to Home
Liquid oxygen (LOX) is a remarkable way to package and transport oxygen. It’s created from fractional distillation of air where oxygen is removed from other gases at its critical temperature and pressure. LOX is stored in cryogenic containers to keep the liquid cold, and it has an 860-1 expansion ratio that allows a great deal of gas to be kept in a small space.
With all that said, the big question clinicians ask is: “So what? We treat patients, not cylinders.”
The reason it’s important for you to understand all that industrial stuff is so that you can know your options when prescribing patients supplemental oxygen and compare delivery devices’ capabilities and limits. An informed clinician is an asset in treating patients as effectively and efficiently as possible.
Outside most hospitals is a large cryogenic container called a cryostat. This container usually holds many thousands of gallons of LOX to supply the hospital its piped oxygen. Why is it liquid oxygen? Again, LOX is the most space efficient method of storing oxygen. It would require hundreds of compressed oxygen cylinders to accomplish this job, and years ago hospitals converted to LOX.
Inside hospitals, however, a great deal of debate exists regarding oxygen for patient transports, and depending on your preference, compressed gas or LOX, each system can be a benefit or a liability.
Traditionally, an E-size cylinder — which can hold 680 liters of oxygen, run to 500 pounds per square inch content pressure (E cylinders aren’t recommended to be run to empty), and weigh 10 to 15 pounds depending on regulators and carts — is used most frequently in hospitals for transport.
However, some hospital administrators are noticing the benefits of LOX portables. A LOX unit with a 1.2 liquid liter capacity translates to 1,035 gaseous liters of oxygen. This would provide 8.6 hours of operating time because the LOX portable can be run to empty. The weight of a 1.2-liter portable is 9 pounds full. These portables operate at 20 psi, yet some have a 50 psi capability.
Hospitals purchase LOX for their large cryostat at pennies a pound, which makes oxygen therapy relatively inexpensive. Cryogenic portable equipment is pricey initially, yet it has a long life cycle and isn’t easily lost or stolen due to its unique nature, which offsets the initial costs.
LOX should be considered for high utilization areas because it has to be used or it will vent (normal evaporation rate). LOX also has some pressure and flow limitations so compressed gas cylinders should be in inventory for powering ventilators or other high pressure/flow circumstances.
Emergency medical services is an extension of hospitals’ emergency departments and often utilizes oxygen in the transport of patients. Some EMS teams choose LOX as an alternative to compressed gas due to the portables’ light weight and convenience. Fixed-wing aircraft and helicopters can extend their range because of LOX’s weight-to-volume advantages. EMS personnel who understand the unique features of LOX can gain maximum benefits.
LOX has a good track record in home care, where it has become a popular option for long-term oxygen therapy patients. The first LOX portables introduced in 1965 weighed 10 pounds, yet they were significantly lighter than E cylinders and improved patients’ mobility. Early cylinders were made of steel with steel carts and brass regulators. The combination of steel and brass weighed close to 22 pounds.
Patients using a LOX portable at 2 Lpm could be mobile for up to eight hours, which was almost double what the patients could get from their cylinders at a weight that was almost half. If you were a patient, which system would you choose?
Several years ago, manufacturers introduced .3 liquid liter LOX portables to the market. These units weigh 4 pounds and can last up to eight hours with an oxygen conserving device (OCD) set at “2.” They earned the distinction of being the lightest, longest lasting portables among oxygen delivery systems.
Each of the .3 liquid liter LOX portables has unique capabilities and limitations. Depending on the OCD settings, these products may not be able to dose enough oxygen to meet the patient’s needs at activity. Patients opt to run at a lower setting to gain operating time at the expense of proper oxygenation.
A solution has come in the form of a small LOX base unit that the patient can take in a vehicle. It’s somewhat like the patient having a gas station with them.
Patients can run the small portable at the necessary setting to maintain proper oxygenation, and if the unit runs out of oxygen before they’re ready to return home, they simply refill the portable from the small base unit. The smallest base is a 10 liquid liters unit that weighs 50 pounds full. The patient also can drive to the home care provider’s location for a fill-up, which can save on a delivery from the provider.
Looking to the future, a manufacturer is working on a home system that would use a concentrator to provide oxygen to a liquefier that could fill a LOX portable. This product would add to the options available to the home respiratory therapist who must meet the patient’s needs in the most effective and efficient way possible.
LOWERING DELIVERY COSTS
The cost to provide long-term oxygen therapy in the home has become a major issue as the rate of chronic obstructive pulmonary disease continues to rise. LOX has a higher delivery cost due to it being a consumable gas. Home care providers can manage the cost of delivery by using equipment as wisely as possible.
The combination of a concentrator and LOX base has been effective in reducing deliveries. Depending on the patient’s mobility and utilization of gas, two LOX base units in the home may be an economic option.
Recently, telemetry has become an option for the home care provider to monitor the patient’s base LOX unit and time refills as strategically as possible. The telemetry software can monitor service and maintenance and can create routing for LOX delivery drivers. LOX always will have a higher cost than oxygen systems that require no service, yet it will be necessary as a clinical option for patients who need its capability.
Some equipment is cheaper than others, yet might not be clinically effective. Expensive equipment may be clinically effective, yet may not be effective in allowing a patient to do daily activities.
The bottom line is to provide the right equipment to be clinically effective, meet the patients’ activities of daily living, and be as inexpensive as possible, in that order.
McCoy is the managing director of Valley Inspired Products Inc., a research and testing company located in Apple Valley, Minn. VIP tests respiratory products for capabilities and limitations to help clinicians understand the products they’re using and equip the clinicians to make informed decisions when utilizing and placing equipment.