Pulmonary embolism (PE) is a potentially life-threatening condition that can present with non- specific symptoms, including dyspnea and refractory hypoxemia, complicating diagnosis, especially in the absence of clinical signs of deep vein thrombosis (DVT). This study retrospectively evaluates the use of computed tomography pulmonary angiography (CTPA) in diagnosing PE in patients presenting with refractory hypoxemia and dyspnea but without clinical evidence of DVT. The relationship between D-dimer levels, DVT presence, and patient outcomes was also explored. Twenty patients admitted to a tertiary hospital between January 2022 and September 2024 were included in the study. CTPA confirmed PE in all cases, while Doppler ultrasound post-diagnosis revealed DVT in 55% of patients despite the absence of clinical symptoms. D-dimer levels varied from 700 to 2100 ng/mL, with higher levels correlating with a more significant embolic burden. ICU admission was required for 50% of patients, and 35% received thrombolysis due to massive PE or hemodynamic instability. The overall mortality rate was 35%, predominantly among patients with malignancy or those requiring thrombolysis. These findings underscore the importance of considering PE in patients with unexplained hypoxemia, regardless of the absence of DVT symptoms. CTPA remains critical for diagnosis, and D-dimer results should be interpreted cautiously, as normal or mildly elevated levels do not rule out PE. Doppler ultrasound is valuable for detecting subclinical DVT. Further studies are needed to develop non-invasive diagnostic protocols for atypical PE presentations.
Pulmonary embolism (PE) is a life-threatening condition that may present with a variety of clinical symptoms, including dyspnea, chest pain, and, in severe cases, refractory hypoxemia (1,2). The latter, characterised by oxygen levels that fail to improve despite appropriate oxygen therapy, may serve as a critical diagnostic clue in patients with unexplained respiratory failure. In many cases, particularly when there are no overt signs of deep vein thrombosis (DVT), PE may go undiagnosed, resulting in delayed treatment and poor outcomes (3).
Refractory hypoxemia in the context of PE can often mimic other conditions such as pneumonia, heart failure, or hemoglobinopathies, complicating diagnosis (4). Therefore, when these conditions are excluded, the possibility of PE should be strongly considered. Computed tomography pulmonary angiography (CTPA) has been the gold standard for diagnosing PE, providing direct visualisation of emboli in the pulmonary arteries (5). In the absence of DVT symptoms, CTPA plays an essential role in identifying PE, particularly in patients with persistent hypoxemia (6).
The present study retrospectively evaluates a cohort of patients who presented with refractory hypoxemia and dyspnea without clinical signs of DVT. It aims to explore the role of CTPA in diagnosing PE and assess the relationship between DVT, D-dimer levels, and patient outcomes.
A retrospective analysis was performed on 20 patients admitted to a tertiary care hospital with refractory hypoxemia and dyspnea between January 2022 and September 2024. Individuals with a pre-existing history of chronic respiratory diseases, like chronic obstructive pulmonary disease (COPD) or interstitial lung disease, were excluded to avoid overlapping symptoms that could affect the presentation of hypoxemia and potentially confound the results. Patients with identifiable alternative causes of hypoxemia, such as pneumonia, heart failure, or hemoglobinopathies, were also excluded to ensure the focus remained on those with suspected pulmonary embolism (PE). Lastly, any patient with incomplete or missing imaging, clinical, or outcome data was excluded to maintain the integrity and reliability of the dataset. None of the patients exhibited clinical signs or symptoms suggestive of DVT, such as leg swelling or tenderness (7). The diagnosis of PE was confirmed through CTPA in all cases. Doppler ultrasound was conducted post-diagnosis to assess for the presence of DVT, and D-dimer levels were measured upon admission (8,9).
Data collected included patient demographics, clinical presentation, risk factors, imaging findings, DVT status, D-dimer levels, treatment modalities, and clinical outcomes (10). Risk factors for PE, such as malignancy, hormonal therapy, recent surgery, and prolonged immobility, were recorded (2).
The primary outcome was the confirmation of PE via CTPA, while secondary outcomes included the detection of DVT, correlation of D-dimer levels with the extent of PE, and clinical outcomes such as ICU admission, need for thrombolysis, and survival (3).
The data were analyzed using a combination of descriptive and inferential statistical methods. Descriptive statistics were employed to summarize patient demographics, clinical characteristics, and outcomes. Depending on the data distribution, continuous variables, such as age and D-dimer levels, were expressed as means with standard deviations (SD) or medians with interquartile ranges (IQR). Categorical variables were reported as frequencies and percentages.
Patient Demographics and Risk Factors
The study cohort comprised 20 patients aged between 31 and 80, with a median age of 60. There was a slight predominance of male patients (55%) (1). Identified risk factors (Figure 1) included malignancy in 20% of patients (n=4), hormonal therapy in 25% (n=5), recent surgery in 20% (n=4), and prolonged immobility in 15% (n=3) (4). Notably, 15% of patients (n=3) had no identifiable risk factors, underscoring the unpredictable nature of PE in some individuals (5).
All patients presented with refractory hypoxemia and dyspnea without clinical signs of DVT. Due to the persistence of hypoxemia, CTPA was performed, confirming PE in all cases (2). The unexplained nature of the hypoxemia drove the decision to perform CTPA despite the absence of typical DVT symptoms (9).
CTPA revealed a variety of embolic distributions: segmental pulmonary emboli were observed in 45% of patients (n=9), main pulmonary artery involvement in 25% (n=5), bilateral PE in 20% (n=4), and unilateral PE in 30% (n=6) (Figure 2) (6). Due to the severity of their condition, patients with bilateral or main pulmonary artery emboli were more likely to require ICU care (10).
Despite the absence of DVT symptoms, Doppler ultrasound identified DVT in 55% of patients (n=11) (Figure 3). The majority of DVTs were located in the femoral (20%) and popliteal veins (20%), with three patients exhibiting multiple vein involvement (7). Interestingly, 45% of patients (n=9) had no detectable DVT on Doppler ultrasound, highlighting the fact that PE can occur without concomitant DVT in peripheral veins (8).
D-dimer levels varied significantly among patients, ranging from 700 ng/mL to 2100 ng/mL
(9). The distribution of D-dimer levels (Figure 4) was as follows: 25% of patients (n=5) had normal to mildly elevated levels (700-1000 ng/mL), 45% (n=9) had moderately elevated levels (1000-1500 ng/mL), and 30% (n=6) had highly elevated levels (>1500 ng/mL) (10). Higher D- dimer levels were generally observed in patients with more extensive embolic burden or those with concomitant DVT (5). However, the study found that normal or mildly elevated D-dimer levels do not exclude PE, particularly in the presence of refractory hypoxemia (4).
Half of the cohort (n=10, 50%) required ICU admission due to the severity of their hypoxemia and embolic burden (7). Thrombolysis was administered in 35% of patients (n=7) who had massive PE or hemodynamic instability, while 65% of patients (n=13) received anticoagulation therapy, including agents such as enoxaparin, dalteparin, and new oral anticoagulants (NOACs)
(9). The overall mortality rate was 35% (n=7), with all deaths occurring in the ICU (10). The highest mortality was observed among patients with malignancy and those requiring thrombolysis (2). Of the surviving patients (65%, n=13), all were successfully treated and discharged (8).
This study highlights the critical importance of considering PE as a potential diagnosis in patients presenting with refractory hypoxemia and dyspnea, even in the absence of DVT symptoms (9). The lack of clinical signs of DVT should not deter the use of advanced imaging modalities, such as CTPA, to confirm the diagnosis of PE (5,10).
Doppler ultrasound remains valuable for detecting DVT in patients with PE, even in the absence of clinical signs (7). This study found that 55% of patients had DVT detectable on Doppler, emphasising the need for comprehensive vascular assessment in patients diagnosed with PE (6). Additionally, the variability in D-dimer levels underscores the limitations of relying solely on this biomarker to rule out PE. Clinicians should interpret D-dimer results with caution, especially in patients with persistent hypoxemia, as normal or mildly elevated levels do not exclude the possibility of PE (8,4).
The severity of the embolic burden largely guided the management of PE in this study cohort. Thrombolysis was reserved for patients with massive PE, while anticoagulation was adequate in patients with less extensive disease (2). Despite aggressive treatment, mortality remained high among patients with malignancy and those requiring thrombolysis, reflecting the poor prognosis associated with severe PE in high-risk populations (3,10).
The study’s small sample size limits the generalizability of our findings. Larger, prospective studies are needed to confirm these results.
Future research should focus on developing noninvasive diagnostic algorithms that integrate clinical data and advanced imaging techniques, reducing the reliance on D-dimer in atypical PE presentations
In conclusion, pulmonary embolism (PE) should be strongly considered in patients presenting with refractory hypoxemia and dyspnea, even in the absence of clinical signs of deep vein thrombosis (DVT) (1, 3). This study highlights the importance of maintaining a high index of suspicion in such cases, as timely diagnosis is critical for effective treatment. Computed tomography pulmonary angiography (CTPA) remains the gold standard for diagnosing PE, and its use is essential in identifying the condition in patients with unexplained hypoxemia (5). Doppler ultrasound, though typically used to detect DVT, is also valuable in these cases, as it can uncover subclinical DVT in a significant proportion of patients (7).
While helpful, Further research is needed to refine diagnostic algorithms and improve survival rates in these patients, particularly by developing non-invasive diagnostic protocols that integrate clinical, imaging, and laboratory data (2, 10). The role of D-dimer levels should be interpreted with caution, especially in patients with persistent hypoxemia. Normal or mildly elevated D-dimer levels do not exclude PE and should not deter further diagnostic evaluation (4, 8). Treatment decisions should be guided by the severity of the embolic burden, with thrombolysis reserved for patients with massive PE or hemodynamic instability and anticoagulation used for less severe cases (9). However, despite aggressive treatment, mortality rates remain high, particularly in high-risk populations such as patients with malignancy or those requiring thrombolysis (2, 10).
Actionable recommendations for clinical practice include the early use of CTPA for diagnostic confirmation (5), the use of Doppler ultrasound to detect subclinical DVT (7), and the cautious interpretation of D-dimer levels in patients with atypical presentations (8). A multidisciplinary approach to patient care is crucial for optimizing outcomes, particularly in high-risk groups (6).
Download PDF
Download PDF
Download PDF
Download PDF
+91 9063922599
+91 9063922599
editor@healthcare-bulletin.co.uk
Download XML
