One Size Doesn’t Fit All

• By Patrick J. Dunne
• Feb 12, 2008

The Clinical Implications of New LTOT Technology
The newest development in long term oxygen therapy (LTOT) is non-deliverable technology that effectively eliminates the need for home visits to periodically re-fill or replace depleted liquid or gaseous oxygen cylinders. Employing differing engineering platforms, all non-deliverable devices have the capability of producing therapeutic oxygen which can potentially satisfy both the stationary and ambulatory needs of most patients.

The economic advantages of non-deliverable technology to the home care provider are obvious since all agree that repeat home deliveries represent one of the biggest monthly expenses. With continuing cost-cutting initiatives for LTOT reimbursement, any strategy that can help contain operating expenses is indeed welcomed.

However, in our rush to embrace the latest and greatest LTOT technology, it is important to ensure that our patients continue to receive the established clinical benefits when newer devices are used.

Clinical Objectives for LTOT
The clinical benefits of LTOT for patients suffering from advanced COPD have been well documented in the medical literature. When properly prescribed and administered, LTOT has been shown to prolong life, reduce exacerbations, forestall the onset of co-morbid conditions (most notably pulmonary hypertension and cor pulmonale), and lead to an overall improvement in the quality of life for this chronically hypoxemic patient population. The dose and duration of LTOT needed to achieve these intended clinical outcomes has likewise been established.

In terms of duration, for the majority of patients, more LTOT is better than less — that is continuous LTOT (greater or equal to 18 hours per day) is better than intermittent use throughout the day. Further, recent studies have shown that the use of LTOT during the pursuit of activities of daily living, including scheduled walking exercise, adds an even greater clinical benefit.

In terms of the correct dose of LTOT to be administered, we now realize that there is not a set, “one-size-fits all” prescription, although for years “2 LPM via nasal cannula” seems to have emerged as the most common physician’s order.

Rather, one should consider the clinical objective of prescribing LTOT, which is to elevate (and maintain) an arterial oxygen tension greater or equal to 60 mm Hg, or alternatively, an SpO2 greater or equal to 90 percent. When blood oxygen levels fall below either of these critical values, it happens on the steepest portion of the oxyhemoglobin dissociation curve, the significance of which is that oxygen desaturation happens quicker and more profoundly with even the slightest drop in the fractional concentration of inspired oxygen.

There is also the issue that when blood oxygen levels fall below 60 mm Hg or 90 percent saturation, physiological compensatory mechanisms, such as pulmonary hypertension, increased cardiac output and respiratory rate, further stress an already impaired cardio-pulmonary system.
Home care respiratory therapists (RTs) are also beginning to appreciate that when patients with chronic respiratory insufficiency desaturate, they instinctively stop doing the activity that precipitated the shortness of breath, fatigue, muscle weakness and other signs symptomatic of inadequate oxygenation. Evidence now suggests it is better for this patient population, both physiologically and psychologically, to stay active.
For several reasons then, it is vital that the amount of oxygen administered is sufficient to keep the blood oxygen level at or above these critical values at all times.

New Technology Introduces New Concerns
The standard 2 LPM prescription might have indeed provided protection from desaturation for the majority of LTOT patients, especially when both the stationary and portable equipment only dispensed oxygen in the continuous flow mode.

However, the introduction of intermittent pulsed dose delivery added a new twist. Initially used only with portable equipment, the new challenge was to ensure that the setting on the pulse portable provided the patient with the same degree of protection from desaturation during ambulation as did the continuous flow setting on the stationary system. The portable pulse oximeter soon became a necessity for the home care RT as did the practice of titrating patients to a comparable pulse dose setting.

One of the new non-deliverable technologies, (portable oxygen concentrators or POCs), introduces yet another challenge. First generation POCs typically only use pulse dose delivery technology for both stationary and portable application, adding yet another unknown to the pursuit of adequate oxygenation.
Of the various non-delivery systems, POCs seem to be most favored by providers and patients alike. Unlike stationary concentrators that either refill gaseous cylinders or provide gaseous oxygen to a liquefier for transfilling a liquid portable, patients using a POC do not need to return home for a refill. POCs are self-sustaining, only requiring an adequate power supply (AC, DC or rechargeable battery). Moreover, POCs are relatively lightweight and easily transportable. With a POC, patients are able to go where they want, when they want and travel in the manner they prefer.

However, in the quest for the lowest weight, there is a trade-off in the amount of therapeutic oxygen (i.e. greater or equal to 90 percent) that a particular unit can produce in a minute. This in turn limits the amount of therapeutic oxygen that can be delivered with each pulsed dose. In some cases, the limit on the amount of therapeutic oxygen produced could compromise the effectiveness of a particular unit to maintain adequate oxygenation for a given patient. For example, should a patient’s breathing rate increase in an attempt to satisfy increased oxygen need, such as often happens during extended ambulation, the patient’s demand could exceed the maximum therapeutic oxygen output of the POC, resulting in desaturation.

Know Your Technology
Non-deliverable LTOT technology, especially POCs, is gaining a lot of traction in the marketplace, but not all POCs are created equal. The maximum production capability of therapeutic oxygen in one minute varies with each unit as does the signature of the pulse dose wave form.

To be sure, many patients might have both their resting and ambulating oxygenation needs met with a pulse dose device. At the same time, there will be those patients who may have their resting needs met with a particular pulse dose system, but not their ambulatory needs. And, no doubt, there will be those patients where pulse dose simply won’t work in either application. For those patients, using a POC with continuous flow capabilities would be the better option.

The successful adoption and use of POCs is not without its challenges, but when properly used, POCs can be a boon for both home care providers and patients alike.
That said, home care RTs now need to know the therapeutic oxygen production capabilities of POCs they are using, how each unit reacts to increased breathing rates and the overall impact on oxygenation.

Moreover, the ability of a particular POC to protect a given patient from desaturation, while at rest and during activity, must be assessed with a pulse oximeter at set-up, and for good measure, periodically thereafter. There is also the question of using a pulse dose delivery system during sleep, but that is an issue for discussion at another time.

This article originally appeared in the February 2008 issue of HME Business.