Platypnoea-orthodeoxia syndrome and hemidiaphragm paralysis

Abstract

A woman in her 70s was admitted to hospital with worsening shortness of breath and no prior respiratory history of note. This patient’s shortness of breath was posture-dependent; symptoms were markedly worse and oxygen saturations were lower on sitting upright than in recumbency. Her shortness of breath had started several weeks prior to admission and had slowly worsened. Chest X-ray revealed a raised right hemidiaphragm. Further investigation revealed a patent foramen ovale, which was managed with percutaneous closure. This is one of several cases that demonstrate right-to-left shunting through a septal defect secondary to right hemidiaphragmatic paralysis. However, previous reports have not provided a clear guide for management of these cases. We suggest where patients are admitted with new onset breathlessness and platypnoea-orthodeoxia, a septal defect should be suspected. In this report, we have suggested a flowchart for the investigation and management of platypnoea-orthodeoxia syndrome.

Background

Platypnoea-orthodeoxia syndrome (POS) is a rare syndrome with multiple underlying causes. In POS, dyspnoea is worse and oxygen saturations are markedly lower when the patient is sat upright/standing. By contrast, dyspnoea and oxygen saturations improve when the patient is recumbent.

POS is rarely encountered in clinical practice and can be difficult to recognise. In turn, it can be difficult to establish the underlying cause of POS. In a systematic review of 239 POS cases, Agrawal et al¹ found that POS was secondary to intracardiac shunts in 87% of cases; secondary to parenchymal diseases in 4% of cases; and secondary to AV shunts in 9% of cases. As demonstrated by this report, intracardiac shunts are the most common cause of POS.

Intracardiac shunts result from a combination of a cardiac defect (eg, an atrial septal defect (ASD)) and raised right-sided heart pressures. The most common ASD is a patent foramen ovale (PFO), which are found in approximately 25% of the population.^2–4 In patients with a PFO, high right-sided atrial pressures and/or distortion of the right atrium can lead to right-to-left shunting (RLS) and POS.

POS is difficult to recognise and there are still a limited number of cases to guide investigation and management. In this report, we present a case of POS in an older patient with a PFO and hemidiaphragmatic paralysis. Previous reports have noted a lack of guidelines for the investigation and management of POS; we have suggested a flowchart of investigations to guide other physicians in the diagnosis and management of similar cases.

Case presentation

A woman in her 70s presented to the respiratory team with shortness of breath and central chest pain. Our patient described her chest pain as pleuritic in nature, ‘deep’ in her chest and radiating to her back. She was hypoxic on admission, requiring 15 L/min non-rebreathe oxygen to maintain oxygen saturations of 83%–85%. Her medical history revealed fatty liver disease; bilateral shoulder and bilateral knee replacements; previous vaginal hysterectomy and bilateral salpingo-oophorectomy. There was no history of trauma or recent surgery.

On observation, the patient was visibly tachypnoeic. On examination, the patient was not cyanosed, there was no peripheral oedema and no peripheral stigmata of respiratory disease. On auscultation, her lung fields were clear with reduced air entry over the right base.

Oxygen saturations were assessed when sitting up and when lying flat; her oxygen saturations improved to 96% when lying flat, compared with 83%–85% when sitting up.

Investigations

Arterial blood gases were performed while the patient was supine and sat up (table 1). Chest X-ray demonstrated clear lung fields, but an elevated right hemidiaphragm (figure 1). CT pulmonary angiogram (CTPA) demonstrated no evidence of any central, segmental or subsegmental pulmonary emboli (PE). Additionally, there was a raised hemidiaphragm, but otherwise normal appearances of the lungs (ie, no parenchymal lung disease) and the upper abdominal organs.

Table 1.

Arterial blood gas (ABG) results (on 15 L/min non-rebreathe oxygen) for the patient when lying supine or sat upright

ABG on room air	Supine	Sat up
pH	7.49	7.51
pO2 (kPa)	7.51	5.04
pCO2 (kPa)	4.97	4.83

Figure 1.

Plain film chest X-ray demonstrating a raised right hemidiaphragm.

Echocardiography demonstrated normal cardiac function with normal ejection fraction (55%–60%). The aortic root appeared prominent and was dilated measuring 39 mm in diameter (25.8 mm/m indexed to height (normal range 13.1–20.7 mm/m)) (figure 2). The interatrial septum was thin and mobile, and there was no trans-septal flow on colour Doppler.

Figure 2.

Long-axis view of the heart on transthoracic echocardiogram demonstrating the five chambers of heart. Aortic root appears prominent and was dilated measuring 39 mm in diameter (25.8 mm/m indexed to height (normal range 13.1–20.7 mm/m)).

Given limited views provided by echocardiography and high suspicion of an atrial septal defect, further investigation with a bubble contrast echocardiogram was arranged. During a bubble echo, the patient is injected with agitated saline and echocardiography is used to examine the flow of bubbles through the heart. In a positive bubble echo study, bubbles flow through the atrial septal defect and are simultaneously observed in both the left and right side of the heart. Flow of the bubbles through the atrial septal defect can also be visualised.

Our investigations demonstrated a strongly positive bubble study without Valsalva in both the supine and sitting position (demonstrated in figure 3, which shows pre-injection and post-injection images of the bubble study). Other features on echo included an aneurysmal aortic sinus.

Figure 3.

Long-axis view on transthoracic echocardiogram demonstrating (left) chambers of the heart pre-bubble injection, (middle) right atrium filled with bubbles and (right) left atrium with bubbles.

Differential diagnosis

Differential diagnoses for this case included a septal defect (eg, a PFO or ASD); an underlying pulmonary embolism; or possible parenchymal lung disease. To treat POS, it is necessary to treat the underlying cause of RLS.

On admission, the patient described sudden onset shortness of breath, hypoxia and pleuritic chest pain. These symptoms were in keeping with a possible PE; a PE is also a recognised cause of RLS and POS. On this basis, the patient scored a Wells’ score of 3. As a next step, a CTPA was performed, which allowed us to exclude a PE and/or parenchymal lung disease

Hypoxia was highly dependent on the patient’s position—a feature of POS, which is commonly associated with an intracardiac shunt. As a next step, simple transthoracic echocardiogram was performed, which was inconclusive. Given the high suspicion of an atrial septal defect, bubble echocardiogram was performed, which provided a conclusive diagnosis of RLS through a PFO.

Treatment

Our team initially managed the patient with supportive care—including supplemental oxygen to maintain oxygen saturation levels. Following investigation, she was shortly transferred to a quaternary referral centre for percutaneous closure of her PFO. She underwent successful closure of the PFO with a 25 mm Abbott PFO closure device.

Outcome and follow-up

The patient was followed-up approximately 4 months after her initial presentation to hospital. At her follow-up appointment, the patient was well with no further issues with hypoxaemia.

Fluoroscopy of the diaphragm reported a raised right hemidiaphragm and paradoxical diaphragmatic movements on sniffing—findings that are consistent with right hemidiaphragm paralysis. Lung function tests were also performed for forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) values (table 2). Spirometry demonstrated improved FEV1/FVC on sitting up and reduced values when lying supine (FEV₁ was 31.5% lower and FVC was 24.4% lower). Predicted values were calculated using the European Respiratory Society online calculator.⁵ Although the RLS/POS had resolved, this patient had poor spirometry values on lying supine (possibly secondary to hemidiaphragmatic paralysis).

Table 2.

Spirometry performed for outpatient follow-up appointment. Predicted values calculated as per the European Respiratory Society calculator (gli-calculator.ersnet.org/index.html) using a height of 150 cm

Spirometry	Predicted values	Sat up	Supine
FEV1	1.65 L	1.46 L	1.0 L
FVC	2.14 L	1.8 L	1.36 L

FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.

Discussion

The pathophysiology of POS has been well-discussed in a previous review.¹ POS is secondary to RLS: deoxygenated blood from the venous system (eg, the right atrium) mixes with oxygenated blood from the arterial system. In RLS secondary to a PFO, blood shunts across the septal defect (ie, the blood bypasses gas exchange in the lungs) leading to lower blood oxygen levels. In certain cases, hemidiaphragmatic paralysis can distort a pre-existing PFO and cause new RLS shunting through the PFO.⁶

There are a small number of case reports featuring POS secondary to PFOs in the literature. Some of these case reports also feature hemidiaphragmatic paralysis.^6–8 For example, the patients reported by Sakagianni et al⁶ and Murray et al⁸ presented with POS secondary to a PFO and hemidiaphragmatic paralysis. Although these cases present similar findings to our case, we demonstrate a simplified pathway for diagnosis and management of POS. Through early diagnosis and management, we were able to avoid unnecessary investigations and, more importantly, deterioration of our patient.

In Sakagianni et al, the patient was initially managed with thrombolysis (for suspicion of massive PE) and later intubated (and transferred to the intensive care unit).⁶ The patient was then investigated using spiral CT and finally diagnosed using echo (both transthoracic and transoesophageal, and finally transoesophageal echo with agitated saline). For the case presented by Murray et al, the patient was initially investigated using cardiac catheterisation, and further investigations included a Technetium-macroaggregated albumin radionucleotide scan.⁸ For the case presented by Sakagianni et al, the PFO was managed using percutaneous closure; in Murray et al, the patient was treated using open surgical repair of the PFO.

Our case demonstrates that the diagnosis and management of POS can be straightforward. Where a patient presents with POS, the most fundamental steps are (1) a careful history, with clear description of the positional nature of the patient’s symptoms; (2) arterial blood gases in the upright and supine positions to confirm the positional nature of orthodeoxia; (3) chest X-ray, to investigate for hemidiaphragmatic paralysis and/or an alternative cause of symptoms; (4) bubble contrast echocardiogram to investigate for an ASD, as this is by far the most common cause of POS; and (5) percutaneous closure of the PFO. If there is reason to suspect an alternative cause (eg, pulmonary embolism with Wells’ score ≥3), then a CT scan (eg, for a PE or for alternate causes of intrapulmonary or extrapulmonary shunts) is warranted.

In our experience, many physicians are unfamiliar with platypnoea-orthodeoxia syndrome, and it can often be difficult to recognise. Our case presents a simple management pathway for these patients to aid in the diagnosis, investigation and management of these patients (figure 4).

Figure 4.

Flowchart of suggested investigation and management of platypnoea-orthodeoxia syndrome (created by Abigail Walker-Jacobs). CTPA, CT pulmonary angiogram; PE, pulmonary emboli; SpO₂, oxygen saturations.

In presenting this case of POS and our suggestions for investigation/management, we hope that other physicians will be more aware of this syndrome and will be able to provide better care through timely diagnosis and management.

Learning points.

• Platypnoea-orthodeoxia is an uncommon finding and there are no published guidelines for investigation and management—we have suggested a guide to investigations and management in this report.

• A careful history is required to ascertain the exact nature of dyspnoea; clinicians should always ask about whether dyspnoea is positional or not.

• Where dyspnoea is positional, pulse oximetry (and, subsequently, arterial blood gases) should be used to identify how oxygen levels differ by position.

• Septal defects are by far the most common cause of platypnoea-orthodeoxia syndrome—new functional defects (eg, hemidiaphragm paralysis) can cause right-to-left shunting through pre-existing septal defects.

• Where patients are admitted with new onset breathlessness and platypnoea-orthodeoxia, an atrial septal defect (most commonly, a patent foramen ovale) should be suspected.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).