Rehab helps resolve platypnoea–orthodeoxia syndrome in COVID-19 patients

Timely and effective rehabilitation interventions can improve orthodeoxia and functional outcome in patients with COVID-19-related platypnoea‒orthodeoxia syndrome (POS), suggests a Singapore study.

“We found that a longer duration of orthodeoxia was related to ICU admission and increased respiratory support,” the researchers said. “Notwithstanding orthodeoxia duration, all cases had resolution of POS and orthodeoxia.”

The mean duration of POS was 12.9 days while that of orthodeoxia was 28.5 days. All COVID-19 patients had resolved POS and orthodeoxia by the time they were discharged. [Singapore Med J 2026;67:52-58]

Multivariable analysis revealed the significant association of ICU admission and maximal level of respiratory support with a prolonged duration of orthodeoxia. One participant was lost to follow-up, while the remaining 23 patients achieved independent self-care. Except for one participant who was recovering from a hip fracture, the rest had independent ambulation and community access.

“Even though good functional recovery was observed in all cases, some participants were still functioning below premorbid levels at follow-up,” the researchers said. “We believe that individualized and targeted rehabilitative therapy, which can safeguard function and prevent deconditioning, delivered while the afflicted individual is coping with POS is key to ensuring good functional outcome.”

Pneumonia

A subset of patients (29.2 percent) in the POS cohort presented with milder pneumonia and required only the use of venturi mask or low-flow nasal cannula oxygen therapy. All participants with POS had concurrent exertional desaturation despite their differences in COVID-19 pneumonia severity.

“Exertional desaturation was noted to resolve later in the recovery process,” the researchers said. “Often, distinguishing exertional desaturation/dyspnoea from POS/orthodeoxia/platypnoea can be challenging.”

However, rehabilitation and medical strategies, such as oxygen supplementation, respiratory techniques/manoeuvres, and paced activities, could be applied to address all these symptoms. [J Rehabil Med Clin Commun 2020;3:1000044]

Mechanism

POS, a rare clinical entity that was first described in the late 1940s, appears to be driven by four pathological processes: intracardiac shunting, ventilation‒perfusion, mismatch intrapulmonary shunting, or a combination of these processes. [Am J Physiol 1949;159:563-564; Tex Heart Inst J 2015;42:498-501]

“The latter processes appear to be responsible for the phenomenon of POS in COVID-19 pneumonia,” the researchers said.

A study by Tan and colleagues first reported POS in COVID-19 and inferred that this could be due to a combination of vasculopathy and increased wasted ventilation, resulting in “a gravitational exacerbation of intrapulmonary shunting.” [Respir Physiol Neurobiol 2020;282:103515]

Most reports of COVID-19-related POS were associated with more severe pneumonia requiring high respiratory support, such as mechanical ventilation, noninvasive ventilation, or high-flow nasal cannula. [Int Med Case Rep J 2023;16:201-207]

The present observational study was conducted in a tertiary hospital managing post-COVID-19 patients. The researchers enrolled 24 patients with severe-to-critical COVID-19 disease/pneumonia and POS, who received inpatient pulmonary rehabilitation. They performed a descriptive analysis of the data to describe POS/orthodeoxia characteristics and functional outcomes among participants.

Finally, factors associated with a prolonged orthodeoxia were identified via correlation analyses.