The Three Phases of Adaptation to PAP Therapy

In the last discussion on the ceiling effect, you will have noticed virtually all the benchmarks refer to how the patient experiences a subjective response to PAP therapy; and, along a broad spectrum, there is strong potential for the patient to discover opportunities for additional improvement.

Running parallel with this proposition to enhance subjective outcomes is the intricately related effort to improve the objective response to PAP therapy, only this aspect is even more problematic from the medical side of the equation, because it appears only a small proportion of sleep specialists recognize all three phases of the PAP therapy adaptation process. 

Phase 1 is the most obvious and arguably the most difficult and therefore receives nearly all the attention from most sleep physicians, at least as far as I can observe, in the sleep medicine community. And, it makes good sense to push hard at the outset, given the research showing that when patients give up after just a few days or week of PAP use, they often drop out of care entirely.

The problem though—one that begs the question—stems from the belief that after a patient undergoes an initial titration, the sleep physician may automatically assume definitive pressure settings were determined on that first ever use of the device. At face value, this tenet would be immediately discredited if we were to consider the analogy of a physician prescribing a medication for say, diabetes or depression or asthma. With many chronic medical and psychiatric illnesses, the dose-response is carefully assessed over time with appropriate tests, validated surveys, or expert clinical interviews. Following a series of appointments that might require weeks, months, or years of gradual or radical changes in the medications and dosages, the patient hopefully responds optimally. Of course, some do not respond well for years and require considerably more trials of myriad therapeutic interventions as well as more changes in medications. 

It seems odd to me that the sleep medicine community does not ascribe to this same dose-response relationship between PAP therapy and sleep-disordered breathing. Put another way, what is the evidence that the initial pressure settings are the optimal pressure settings? In our own clinical experience, we rarely find best pressures the first time a patient is exposed to PAP therapy. An interesting aside here is that we come much closer to finding best pressures in someone who has used fixed CPAP for years, who is seeking a second opinion due to a sub-optimal response. When these folks return to the lab, they have already passed through Phase 1 of PAP therapy adaptation, because their body has adapted at least somewhat to the unnatural psychophysiology of using pressurized airflow, and the histopathology in their upper airway may have returned or be in the process of returning to a pre-morbid state, one with less edema or other signs of inflammation caused by sleep apnea. Thus, it is not unusual for a second opinion patient to pass right into Phase 2 when they are exposed to more advanced PAP technology such as bilevel. Most of these patients immediately recognize the enhanced comfort factor of dual pressure systems, and objectively this comfort shows up physiologically as the patient tends to enter and maintain more time in REM sleep duration this retitration study compared to what they were experiencing on their CPAP devices.

For many patients, then, Phase 1 often takes months to attain a degree of adaptability where use is regular, subjective improvements are noted, and objective data on downloads shows some reduction of breathing events albeit often in common with residual breathing events. The single most relevant caveat of the entire Phase 1 process is nearly all patients truly needed higher pressure to resolve sleep-disordered breathing (described at our lab as: AHI < 1, RDI < 5 to 10 range), but they could not tolerate higher pressures (particularly on expiration) on the very first night of exposure to PAP therapy, just prior to filling the prescription for the device. Thus, the goal of establishing the proper dose-response to PAP therapy is effectively a non-starter in the sleep lab for the vast majority of patients, so much of a non-starter that a strong case could be made to put every patient on an APAP or ABPAP device directly after their diagnostic study, and then schedule each patient for a full night titration study 2 to 8 weeks later, depending upon their response. Again, the two main Phase 1 barriers are that patients must pass through a psychophysiological adaptation process to the device while at the same time the tissues in their upper airway must normalize to some degree, after which the patient has started or completed the transition from Phase 1 to Phase 2 and is ready to attempt higher pressures.

Phase 2 is arguably the most interesting phase of PAP therapy adaptation, because it is incredibly obvious to the sleep technologist that the pressures are off when the patient returns for the retitration. Pressures are almost always too low, and it is incredibly obvious to the patient that with higher pressure settings, the response is clearly improved beyond what he or she was currently experiencing. In this instance when patients are persuaded to return for the retitration study, they most often objectively burst through the “ceiling” effect, which teaches them the very next morning there is a “more better” to be gained by tweaking pressure settings. Perhaps the most interesting aspect of Phase 2 is how well it mirrors the patient’s perspective on the ceiling effect and how that influences the capacity of the sleep clinic staff to persuade the patient to return for a retitration PSG. Of notable clinical import, most patients who return for the retitration remark on their good fortune by having followed through to reassess pressure settings. Whereas, a very sizeable minority of patients will never agree to return to the sleep lab, no matter how well they are educated on the dose-response conceptualization. Regrettably, it is my opinion that this concept is not delved into on a regular basis for most PAP therapy users, even though, again in my opinion, most PAP users need the retitration experience several weeks or months after the first procedure.

Instead, Phase 3 kicks in for those “squeaky-wheel” patients who have the good sense to pay close attention to the broad symptom complexes related to their sleep breathing problems. Often, they notice renewed trips to the bathroom at night, the return of morning headaches, greater difficulties controlling blood pressure, noticeable changes in weight (both up or down), more sleep fragmentation and of course worsening of daytime fatigue and sleepiness. I presume most sleep centers operate effectively in the realm of Phase 3, because this area often relates to the renewed complaints just described. Thus, the sleep physician makes the reasonable assumption that when the patient is complaining about a return of symptoms, then a change has occurred that requires a new assessment of pressures.

This Phase 3 reassessment may occur with simpler tasks such as confirming the device is working properly, checking the leak status, or refitting a mask. Among sleep centers willing to go the extra distance, objective data downloads (ODDs) are obtained to clarify leak, residual breathing events or snoring, and hours of use. However, there are many flaws in the ODD system such as the inability to gauge accurately residual flow limitation events (UARS, RERAs), the lack of a measure for leg jerks, or the lack of clarity on whether the patient’s residual breathing events might be central apneas. Thus, the ODD fares poorly in comparison to a retitration study, which is why some sleep professionals over the years have recommended the annual retesting approach.

Annual retitrations would likely benefit a great many patients, especially among those individuals wandering around in Phase 2 while unable to optimally adapt to the device and thus continue to miss out on the opportunity for determining optimal pressure settings. One classic example of this scenario is the individual who consistently suffers acute on chronic mask fit difficulties for months and sometimes years on end. Another example would be the individual whose treatment response to periodic limb movements remains sub-par. One more example would the mental health patient, particular a person suffering from depression, who is unable to accurately detect the differences in changes in fatigue and sleepiness as it relates to their co-morbid sleep and depressive symptoms.

Notwithstanding, the annual retitration approach is clearly frowned upon by many in the sleep medicine community and certainly among insurance carriers or government regulators. And, it certainly is a reasonable stance to expect that there would be solid indications to return to the sleep lab for the retitration. My experience and my point here merge into the strategy that recognizes that if the dose-response curve for the treatment of sleep apnea with PAP therapy is a scientifically valid and clinically viable construct, then logic would inescapably predict that there is a spectrum of adaptability among sleep apnea patients. This spectrum as outlined above and based on my experience tends to follow through 3 Phases for the majority of sleep apnea patients. 

In sum, whatever is required to push the patient through all these phases of adaptability, including multiple retitrations to find the correct dose-response of pressurized air, is a program that might seem expensive at first blush. However, careful scrutiny of the cost-value data among PAP users strongly suggests this effort is cost-effective over the long-term.


Barry Krakow MD


Dr Krakow’s 27 years of sleep research have focused on the complex relationship between physiological and psychological sleep disorders. Dr Krakow currently operates private sleep medical center, Maimonides Sleep Arts & Sciences, Ltd., and serves as Classic SleepCare’s paid Medical Director.

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