Prof. Dr. med. Thurnheer, Cantonal Hospital Münsterlingen, impressively demonstrated that it is not always necessary to be satisfied with the working diagnosis of “dyspnoea of unclear aetiology”, but that detailed anamnesis and appropriate clarification steps can often identify underlying causes and provide patients with appropriate treatment. Particularly in multimorbid patients, however, identifying and interpreting the pieces of the puzzle relevant to dyspnea diagnosis is not an easy challenge given the usually complex findings.
If a patient feels that they are no longer getting enough air, this can be due to many different factors. “Dyspnoea is a subjective symptom,” says Prof. Dr. med. Robert Thurnheer, Head of Internal Medicine at Münsterlingen Cantonal Hospital [1]. The outwardly perceptible signs may be shallow and rapid breathing or markedly deep breathing. As breathing is a complex process that is influenced by pulmonary, cardiac, muscular, skeletal and cerebral factors, among others, the spectrum of possible causes of dyspnea is broad.
Case 1: Hypertensive heart disease
An 82-year-old female patient suffering from dyspnea had recently had influenza A and was known to have arterial hypertension and atrial fibrillation (AFib). Some time ago, she had fallen at home. She also suffered from diarrhea after receiving nitrofurantoin for a urinary tract infection. The x-rays showed a basoapical redistribution. The cardiothoracic index (heart/thorax ratio) was above 0.50. There was pulmonary venous congestion and fluid in vessels, as well as recruitment of pulmonary circulation in upper fields (increase in wedge pressure to 13-18 mmHg). Further features in the X-ray findings: interlobar effusion, peribronchial cuffing, silhouette phenomenon (diaphragmatic contour not clearly recognizable); “Kerley lines”. The Kerley lines are fine, horizontal lines that extend to the thoracic wall and are a sign of heart failure, explained Prof. Thurnheer [1]. A CT abdomen taken a month ago was also helpful in this case, as it would have been possible to detect pulmonary fibrosis caused by nitrofurantion, for example. If there is a suspicion of drug-induced pneumological symptoms, the website www.pneumotox.com [1,3].
Dyspnea is known to be a possible sign of left heart failure. If the presence of HFpEF, HFrEF or HFmrEF is confirmed, treatment should be carried out in accordance with the guidelines. With regard to loop diuretics, torasemide and furosemide are considered equivalent in heart failure according to current knowledge [4]. “It probably doesn’t matter whether you give furosemide or torasemide,” Prof. Thurnheer admitted [1]. Compression bandages can be helpful in mobilizing patients. In patients with AF, experience has shown that frequency monitoring is often sufficient, depending on patient characteristics, while rhythm monitoring is unnecessary, the speaker reported [1]. Whether opiates should be prescribed for dyspnea is a controversial issue. “People like to give morphine when someone has dyspnoea,” says Prof. Thurnheer [1]. However, there is little data on this. For tumor patients with dyspnea, however, morphine is a well-established treatment option.
| When is ergospirometry useful? |
| “Ergospirometry is a relatively good way of finding out whether a limitation is cardiac or pulmonary-mechanical,” explained Prof. Dr. Thurnheer. Pulmonary-mechanical dyspnea is classically caused by asthma and COPD. Those affected are so limited that they can hardly breathe after a short time, which is clearly shown by ergospirometry. It is also possible to detect a diffusion disorder (gas exchange) if the ventilation ratios between oxygen andCO2 are out of balance. But it doesn’t always have to be the heart or the lungs, it could also be deconditioning, the speaker pointed out. When 55-year-olds say that they used to run half marathons but can no longer get up the hill, this may be a normal age-related phenomenon or simply a lack of training. However, there are also rare muscle diseases such as mitochondrial myopathy; in such cases, those affected become hyperacidic very quickly, i.e. the ventilatory equivalents forCO2 increase. |
| according to [1] |
Case 2: Pulmonary arterial hypertension
In the next case example, the speaker described a young woman who presented to the emergency department with dyspnea and cyanosis and reported that she was suffering from physical and mental exhaustion [1]. The chest X-ray findings were unremarkable and the patient had normal lung function. Echocardiography should be performed in young women with such symptoms, a normal chest X-ray and normal lung function, emphasized Prof. Thurnheer [1]. If pulmonary arterial hypertension (PAH) is present, the cardiologist will most likely detect pulmonary hypertension and right heart strain. In the case study, it turned out that the patient was suffering from idiopathic PAH. “This is a very rare disease that occurs more frequently in women,” explained Prof. Thurnheer [1]. Around two thirds of all those affected are women and registry data shows that there is often a diagnosis latency of >1 year [2]. Nowadays, PAH can actually be treated well with medication. “Fortunately, there are new drugs that have massively improved the prognosis and quality of life,” said the speaker [1]. The normal values for pulmonary artery pressure are shown in Figure 1 .
Case 3: Heart rate drop
A 52-year-old athletic man with a history of Hodgkin’s disease and coronary heart disease (CHD) complained of dyspnea during exercise. The patient felt restricted by this and was worried [1]. Angina pectoris could be ruled out. Radiotherapy performed in the mediastinum was a possible explanation for the CHD (branch vessel disease). A coronary angiography was performed to see if he had a progression of CHD, which was not the case. Pulmonary function testing revealed unremarkable findings; all values, including VEF1, lung mechanics and diffusion capacity, were within the normal range. The next step was to carry out ergospirometry. The results were as follows:
- 50 watts, increase 75 watts per 3 min
- Power 162 watts (= 82% of the setpoint)
- Heart rate drop from 114 to 65 at 150 watts
Prof. Thurnheer explained that the patient was performing at around 80% of his target value, but considering that he works physically (in civil engineering) and is very athletic, 120% would have been expected [1]. The drop in heart rate from 114 to 65 at a power output of 150 watts was striking. “This is a frequency-dependent bundle branch block,” explained the speaker [1]. A beta-blocker had already been discontinued some time ago, which did not lead to the disappearance of this bundle branch block.
The final diagnosis for this patient was as follows:
- Frequency-dependent AV block with 2:1 to 3:1 conduction, persistence after discontinuation of the beta blocker
- Status post Hodgkin’s disease 1982 with mediastinal radiotherapy.
- In view of this diagnosis, the decision was made to implant a pacemaker, after which the patient’s condition improved.
Case 4: Bilateral sequential diaphragmatic paresis
A 69-year-old patient with new-onset dyspnea had recently undergone a prostatectomy (Da Vinci surgery) [1]. He also had a positive D-dimer (or “non-negative D-dimer”) and a history of a non-ST elevation myocardial infarction (NSTEMI). In the meantime, the patient had a stent and was taking aspirin and ticagrelor. Recently, he has been suffering from severe dyspnea, especially when lying down. He had previously worked as a baker, but had to give up this profession because he developed baker’s asthma. Since then, he worked as an innkeeper, was married, had two sons and hardly ever consumed alcohol. Although he was a non-smoker, he had COPD GOLD 3B and was overweight with a BMI of 34.8 kg/m2 (obesity grade 1 according to the WHO). He also had a left-sided diaphragmatic paresis, which had been diagnosed during an earlier pneumological examination.
During the current assessment, it was noticed that he hyperventilated when lying down and was somewhat tachypneic when sitting up. The respiratory rate showed good saturation, the pulse was normal, the blood pressure elevated. A vesicular breath sound was heard, somewhat weakened basally. Blood gas analysis (ABG) revealed a slightly elevated pCO2 and a normal arterio-alveolar oxygen gradient (2.2 kPa). The ECG proved to be unremarkable. Echocardiography was only possible in a sitting position and could therefore only be assessed to a limited extent. The systolic function proved to be highly normal.
Ultrasound of the thorax revealed a bilaterally elevated diaphragm and this finding was also clearly visible on CT. A spirometry was also carried out. There was a difference of 33% between lying and standing, which is a strong indication of diaphragmatic paresis, Prof. Thurnheer noted, explaining that the difference should be around 15%. In the end, the diagnosis of bilateral sequential diaphragmatic paresis of idiopathic cause was agreed for this patient. The initial differential diagnosis was a suspected pulmonary embolism, as patients with prostate cancer belong to a risk group. However, the venous duplex (CT angiography) showed no evidence of deep vein thrombosis. Other DDs that would have been theoretically possible in view of the history: Pompe’s disease, obesity-hyperventilation syndrome, bilateral sequential diaphragmatic paresis, drug side effect.
With regard to treatment, non-invasive ventilation was prescribed, i.e. a mechanical breathing aid (e.g. nasal or mouth-nose mask) without an endotracheal tube or tracheostomy tube. This measure quickly led to an improvement in this patient’s symptoms.
| Other possible causes of dyspnea |
| In addition to those described in the case studies, there are many other possible explanations as to why patients experience breathlessness. These include hyperventilation due to psychological factors (especially anxiety), intoxication with salicylates or ticagrelor, ketoacidosis as a side effect of SGLT-2 inhibitors, anaphylaxis or sepsis. However, myopathies in the context of amyotrophic lateral sclerosis, mitochondrial myopathy, polymyositis or dermatomyositis or neuralgic shoulder amyotrophy can also manifest themselves in dyspnea. With regard to Covid-19, dyspnea is a possible symptom, although there have been cases with hypoxemia but without dyspnea. Indications that this may be a cardiac rather than a pneumonic problem should be sought in the history. Particular attention should be paid to the following: CHD, heart valve replacement, hypertension, VHF, orthopnoea, nocturia, weight gain, edema, large heart, redistribution, elevated BNP (caution: incorrectly low, e.g. in obesity or not elevated in constrictive pericarditis or in the case of an acute mitral cord rupture). |
| according to [1] |
Case 5: Ketoacidosis due to starvation
A 70-year-old woman suffered from dyspnea, nausea and vomiting. She hadn’t eaten anything for four days. From the clinical impression, the hyperventilation was striking. There was no evidence of any neurological symptoms. The arterial blood gas analysis (ABGA) showed that the patient had metabolic acidosis and hyponatremia. The anion gap was within the normal range (Na Cl Bic=9). The patient had neither renal insufficiency nor diabetes and was not taking any medication that could have explained the abnormalities in the ABGA. Acetone, i.e. ketone bodies, was found in the urine. “This patient has ketoacidosis,” concluded Prof. Thurnheer [1]. This was described as “pseudo normal anion gap starvation induced (beta hydroxybutyrate) ketosis”.
A subsequent gastroscopy revealed that the patient had severe reflux esophagitis, which was very painful, so that she could no longer eat. The ketoacidosis was corrected by supplying NaCl and glucose. After correction, the patient’s values normalized, including sodium, osmo, ph,CO2, oxygen saturation and bicarbonate. The speaker pointed out that a slow correction of sodium is generally carried out (maximum 8 mmol per 24 hours), although the data do not necessarily speak against a rapid correction.
Congress: Davos Medical Forum
Literature:
- “Dyspnoea, cardiac, pulmonary and ‘everything beyond'”, Prof. Dr. med. Robert Thurnheer, Davos Medical Forum, 05.03.2024.
- Khou V, et al: Diagnostic delay in pulmonary arterial hypertension: Insights from the Australian and New Zealand pulmonary hypertension registry. Respirology 2020; 25(8): 863-871.
- “The Drug-Induced Respiratory Disease Website”, Philippe Camus, MD, www.pneumotox.com/drug/index,(last accessed 22.03.2024).
- “Which diuretic works better?”, https://app.cardionews.de/Aktuelles/Welches-Diuretikum-wirkt-besser-434858.html,(last accessed 22.03.2024).
HAUSARZT PRAXIS 2024; 19(4): 16-17 (published on 18.4.24, ahead of print)
