Ascending aortic dissection diagnosed with the use of point-of-care sonography. Case report.

The presented case of a patient in cardiogenic shock in the course of aortic dissection with concomitant cerebral circulation illustrates the effectiveness of sonography in the intensive care unit as a tool that aids the diagnostic process. Point-of-care sonography involves ultrasound assessment performed by the attending physician, being an integral part of a physical examination. A 67-year-old female was brought to the emergency department with a suspicion of stroke, comatose, with focal neurological deficits and was admitted to the intensive care unit due to circulatory and respiratory failure. Based on the findings from a bedside ultrasound examination, the diagnostic process was extended, and the patient was rapidly transferred to the department of cardiac surgery with diagnosed ascending aortic dissection. The case presented demonstrates how point-of-care sonography facilitates and accerelates the diagnostic process and speeds up the implementation of de finitive treatment thus affecting the patient's outcome.

Introduction

Point-of-care ultrasound (POC US) involves a bedside ultrasound examination performed by the attending physician who is not a specialist in radiology/sonography and who can draw conclusions concerning further management based on the outcome of the examination. POC US uses simplified protocols (e.g. FAST – focused assessment sonography in trauma, FEEL – focused echocardiographic evaluation in life support, FATE – focused transthoracic echocardiography in emergency, BLUE – bedside lung ultrasound in emergency), whose aim is to detect significant pathologies impacting the patient's condition. Information gathered with the use of POC US should entail early implementation of treatment addressing the main cause(. The POC assessment does not always allow the definitive diagnosis to be established, but it enables the diagnostic process to be limited to examinations that directly confirm or rule out the initial diagnosis.

Case report

A female aged 67 was brought to the emergency department at 7:30 due to abrupt loss of consciousness. The patient was found at home, comatose, with stertorous breathing. At the emergency department, she was assessed in neurological examination and was found unconscious, responding only to deep painful stimuli. The pupils were equal, narrow and reactive to light; meningeal signs were difficult to assess. On the right side, the extremities were found considerably spastic, and on the left, flaccid paresis of the upper and lower extremity was observed. Due to the suspicion of stroke, a head computed tomography (CT) scan was performed, but no focal lesions were found in the central nervous system (CNS). Brain perfusion disorders were diagnosed due to circulatory insufficiency. Because of the severe general condition as well as circulatory and respiratory failure, the patient was intubated and ventilated. Subsequently, at 8:40, she was transported to the intensive care unit (ICU).

In the ICU, shock was diagnosed (heart rate 130/min, arterial pressure 100/50 mm Hg). Dobutamine infusion was started in order to stabilize the circulatory system. Mechanical ventilation was continued. An arterial blood gas test revealed metabolic acidosis with elevated lactate concentration up to 6.8 mmol/l. Immediately after admission to the ICU, a POC US examination was conducted (GE Logic E system, 4C-RS convex probe, 2–5 MHz). During lung assessment (the BLUE protocol)( the following were observed: bilateral lung sliding present, numerous symmetrical B lines on both sides. Findings consistent with lung edema (fig. 1).

Fig. 1

Pulmonary edema. Numerous B-lines. Retained sliding sign

The heart, whose assessment was based on simplified echocardiography protocol (FATE)( (3S-RS sector probe 1.7–4 MHz), was hyperkinetic with the left ventricle without contractility impairment. In the apicalfive-chamber view, it was found that a hyperechoic structure bulged into the ventricle in the diastolic phase through the left ventricle output tract, which could suggest that the separated tunica intima of the aorta was causing aortic regurgitation (fig. 2, 3). In the subcostal four-chamber view, the inferior vena cava was dilated to 2.6 cm with no change during respiration.

Fig. 2

Apical four-chamber view. In the outflow of the left ventricle, the echo of the dissected tunica intima of the aorta is visible. A4Ch

Fig. 3

Parasternal long axis view. The echo of the aortic tunica intma is visible in front of the aortic bulb. PSLX

Subsequently, the carotid arteries were assessed (8L-RS linear probe 4–12 MHz), and a hyperechoic structure was found in the right common carotid artery which almost completely filled its lumen (fig. 4, 5).

Fig. 4

Right common carotid artery (long axis)

Fig. 5

Right common carotid artery (transverse axis)

The result of the comprehensive ultrasound examination and the clinical picture allowed an initial diagnosis to be established. The patient was diagnosed with acute heart failure caused by ascending aortic dissection with secondary aortic insufficiency, occlusion of the right common carotid artery and impaired cerebral circulation.

In order to confirm the diagnosis, a comprehensive echocardiography was conducted, and then, at 10:45, CT angiography was performed which revealed dissection of the ascending part of the aorta and aortic arch involving the wall of the brachiocephalic trunk (occluded vessel) and the left common carotid artery.

Following a consultation with a cardiac surgeon, the patient was qualified for a surgical treatment, and at 14:40, she was transported to the cardiac surgery department.

In the operating room, monitoring of the regional brain oxygen saturation rSO2 was started with the use of an INVOS system. The examination confirmed considerable asymmetry in perfusion shown previously in the carotid artery US examination and CT angiography. After the chest and pericardial sac were opened, the dilated (to 8 cm) ascending aorta was found with the visible intima moving together with the current of blood under the tunica adventitia. The tear originated 2 cm from the aortic arch. The aortic tunica intima rolled up to the aortic valve and arch together with the current of blood and occluded the carotid vessels. Such an image of the tear made it possible to leave the patient's own aortic valve and place a straight graft below the site of the aortic tear, which joined the ascending aorta with the fragment of the aortic arch with an “end to end” anastomosis. A part of the procedure was performed in deep hypothermia in 20°C with complete circulatory arrest. A selective brain perfusion was conducted during circulatory arrest, controlled with regional brain oxygen saturation. From the moment of brain vessel cannulation, the results of rSO2 were normal.

In the first three days following the surgery, features of heart failure were observed that required a considerable support with the use of inotropic agents. From day 4 after the surgery, the circulatory system was stabilized, and cardiac markers were gradually normalized.

On day 7, the patient was transferred from the cardiac surgery department to the ICU. At admission, the consciousness level was assessed as GCS 4 (Glasgow Coma Scale). A head CT scan revealed numerous foci of stroke. During further course of treatment, the patient suffered ventilatorassociated pneumonia. Due to difficulties with discontinuing mechanical ventilation, it was necessary to perform percutaneous tracheotomy. In the subsequent days, when the consciousness status had improved, the symptoms of left-sided hemiparesis and pseudobulbar palsy were observed. Due to disorders in swallowing, gastrostomy was performed. During the patient's stay in the ICU, passive and active rehabilitation was conducted, which resulted in assuming the vertical position by the patient. An antidepressant therapy was started as well. After 54 days from the onset, the patient was discharged to continue further out-patient treatment.

Discussion

Point-of-care sonography is becoming more and more common as a tool for comprehensive assessment of patients in emergency. It helps to find reversible causes of circulatory arrest, differentiating shock causes and respiratory failure, as well as facilitating early assessment of trauma patients. Owing to POC US, it is possible to establish a diagnosis and implement a specific treatment without delay resulting from the unavailability of radiological studies and hazards associated with the necessity of transporting patients to a diagnostic laboratory(. In the case presented above, POC US, used as a part of US-assisted physical examination, made it possible to suspect that aortic dissection was the underlying medical problem, and it enabled a specific diagnostic process to be conducted leading to the confirmation of the initial diagnosis. It must be emphasized that thanks to POC US, the suspicion of aortic dissection was made within 30 minutes of the admission to the ICU, and the final diagnosis was confirmed within further 2.5 hours. The usage of US as a tool that complements the clinical examination caused a significant change of the direction of the therapy and enabled rapid implementation of definitive treatment, which in this particular case undoubtedly saved the patient's life.

Apart from POC US being used in patients in a critical condition, this method is also a valuable tool that facilitates daily treatment of patients who require intensive care. It helps to assess the body fluid status(, heart function and response to the implemented treatment(, aeration of the lungs( and the condition of vessels (arterial and venous) and abdominal organs as well as estimate the intracranial pressure(. US-assisted clinical examination is characterized by a considerably higher diagnostic sensitivity, helps gain better knowledge about the condition of patients, accelerates definitive diagnosis and helps monitor the effects of the implemented therapy(. Due to the aforementioned benefits and non-invasiveness, it seems that POC US should be the first line diagnostic tool for patients treated in intensive care units and emergency departments.