Conclusion:
This case illustrates the fundamental role if transesophageal
echocardiography in critically ill patient with shock due to
high-probability pulmonary embolism. It allows the initiation of
adequate treatment without further delay.
Keywords:
Acute pulmonary embolism, transesophageal echocardiography,
transthoracic echocardiography, CT chest angiography
Introduction:
Pulmonary embolism (PE) could be difficult to diagnose especially in
critical ill patient who are hemodynamically unstable notably if the
classic symptoms of PE are absent (1). Although, many cases of PE are
diagnosed in emergency context (2). So echocardiography could be
considered as useful technique at the bedside in critical care settings
for the diagnosis of PE, especially when it is unable to get other
confirmations studies (2). That is why, we present this case of massive
pulmonary embolism diagnosed by the combined use of transthoracic
echocardiography (TTE) and transesophageal echocardiography (TEE) due to
the poor transthoracic window. TEE was useful by helping in ruling out
differential diagnosis of the cause of this shock and finding signs in
favor of the diagnosis of PE, which allowed the initiation of adequate
treatment without further delay. So, the aim of this case report was to
highlights the pivotal role of TEE in the diagnosis of PE in an
hemodynamically unstable patient especially when his mobilization is
difficult to achieve.
Case presentation:
A 47-year-old man, with no medical history, previous treatment or toxic
habit was admitted at hospital with a diagnosis of isolated closed
fracture of his right leg due to a road accident (He was struck by a
motor vehicle). At the time of admission, he was conscious, without any
neurological alteration or hemodynamic and respiratory disorders.
24 hours after the admission, the patient presented suddenly a change in
his level of consciousness (confusion with Glasgow come scale of 12). He
was tachypneic (30 breaths/min) with an oxygen saturation of 94% with a
non rebreather mask. Lung auscultation showed conserved vesicular murmur
with bilateral basal crackles. He was tachycardic (heart rate 120
beats/min) and presented a hypotension (blood pressure was 80/40 mmHg).
He was not febrile and did not present any cutaneous sign. A 12-lead
electrocardiogram showed only a sinusal tachycardia without other signs
of acute coronary syndrome or right heart strain. The patient was
immediately treated with crystalloid fluid infusion and bolus of
epinephrine. After that, brain scan was done (without post traumatic
abnormalities) in addition to thoracic CT angiography which did not show
any sign of acute pulmonary embolism (Figure 1).
Therefore, he was transferred in emergency to the ICU and due to his bad
evolution, he was intubated and required mechanical ventilation.
Arterial acid-base balance at that time showed fraction of inspired
oxygen 100%, pH 7.15, partial pressure of oxygen 86 mmHg, partial
pressure of carbon dioxide 52 mmHg, bicarbonates 24 mmol/L, base excess
-15, lactic acid 2.5 mmol/L and oxygen saturation 93%. Laboratory
finding hemoglobin 10g/dl, leukocytes
6.103/mm3, lymphopenia, creatinine
1.5 mg/dl, troponin T 34 µg/L, pro-BnP 400 pg/ml and procalcitonin
< 0.05. His respiratory status failed to respond to high-dose
of vasopressor and ventilatory support so nitric oxide was introduced in
addition to continued infusion of cisatracurium. Chest radiography
showed bilateral infiltrate (Figure 2).
In order to determine the real cause of this instability, TTE was
performed however we obtained poor quality images so it was necessaire
to complete with TEE which was performed by an experiment
anesthesiologist. TEE demonstrated a dilated and dysfunctional right
ventricle (RV) with an hypertrophic dysfunctional left ventricle (LV).
The right atrium (RA) was also severely dilated with a patent foramen
oval and septum bowling (Figure 3). The RV end-diastolic diameter to LV
end-diastolic diameter ratio was 1.2 suggesting RV pressure overload. RV
dilatation leaded to functional tricuspid regurgitation as the tricuspid
annulus enlarged. There was a pulmonary arterial hypertension with a
pulmonary artery systolic pressure of 70-80 mmHg. Initially, there was
no evidence of a thrombus either in the pulmonary arteries or on the
right side of the heart. Due to global heart failure and the
low-cardiac-output state, dobutamine was used with the doses of 3-5
µg/kg/min. However, after 24 hours, a control TEE showed an evident
thrombus in the right pulmonary artery which was dilated (Figure 4).
Massive pulmonary embolism was suspected but we could not confirm it by
other complementary test because the unfavorable hemodynamic situation
of the patient prevented his transfer. Anticoagulant therapy
(non-fractioned heparin) was administrated immediately achieving a
favorable clinical outcome with rapid withdrawal of dobutamine, nitric
oxide and cisatracurium.
Discussion:
This case highlights the crucial role of echocardiography in ICU for
patient with severe shock due to massive pulmonary embolism associated
to an unfavorable hemodynamic situation. In addition, like many similar
cases published in literature, it illustrates the value of TEE over TTE
for those who have poor transthoracic window secondary to some clinical
situation (supine position or mechanical ventilation) (1).
Pulmonary embolism could be difficult to diagnose particularly for
patient in ICU who are sedated or on mechanical ventilation because key
symptoms are absent (Dyspnea, chest pain and syncope). For the diagnosis
of PE, pulmonary angiography and spiral CT is the gold standard with a
sensitivity of 83% and a specificity of 96% according to the PIOPED II
trial (3). However, in our scenario, the CT angiography performed
initially did not show any sign of acute pulmonary embolism despite the
high probability of PE and this could be explained by the occurrence of
artefacts or secondary migration of subsegmental thrombosis. So
echocardiography was useful in order to ruling out some differential
diagnosis which caused this hemodynamic instability (tamponade, aortic
dissection, hypovolemia…) according to the guidelines of European
Society of Cardiology (4).
Vignon et al showed that TEE helped in 98% of clinical decisions in
critical care population so it has higher impact on patient care that
TTE which provided adequate images in only 38% of cases (5). Concerning
the confirmation of PE, TEE has 70% sensitivity and 81% specificity
(6). In context of PE, TEE usually shows indirect signs like RV
dilatation (RV end-diastolic diameter/LV end-diastolic diameter ratio
> 0.9) and exclude other causes (7). In addition, serial
assessment of RV size, determination of RV systolic pressure and
inferior vena cava assessment could be performed in patient with massive
PE. Although, thrombus may be seen in some cases. According to Pruszczyk
et al (8), the central pulmonary arteries including the proximal lobar
branches on both sides could be precisely visualized by biplane TEE.
Only the proximal left pulmonary artery is difficult to assess because
it is shielded by the left main bronchus. But a perimural artefact may
be potentially misinterpreted as thrombus especially when it is present
in the right pulmonary artery (9).
Besides, significant hemodynamic instability is present in 8% of
patient with acute pulmonary embolism. The main cause is acute right
ventricular failure which increase mortality from 15% to 42% (10).
That is why, TEE could be useful for analyzing response to medical
interventions such fluid and drug therapy. It could also be helpful for
monitoring RV function and pulmonary artery systolic pressure especially
if thrombolytics or anticoagulant were administrated (11).
Conclusion:
We reported this case in order to insist on the fundamental role of TEE
in ICU especially when the transthoracic window is poor. It allows the
initiation of adequate treatment without further delay, by avoiding an
unnecessary mobilization of an unstable patient to perform CT chest
angiography leading to a better clinical outcome. Although, it has some
limitations like the cost of the equipment or the inability to place a
probe (esophagectomy, esophageal diverticula or varices) however,
complications rates from TEE use are fairly low 0.2% (12). In addition,
it was demonstrated that it had a steep learning curve and that
physicians could successfully perform focused TEE assessments with a
high retention rate after 6 weeks of 4-hour simulation workshop (13).
Figures legend:
Figure 1: CT chest angiography
Figure 2: Chest radiography
Figure 3: Mi esophageal 4-chamber view
Figure 4: High esophageal view
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