|LETTER TO EDITOR
|Year : 2014 | Volume
| Issue : 3 | Page : 362-363
Post-operative pulmonary embolism: Transthoracic echocardiography as a diagnostic tool
MP Nikhil, Avanish Bhandary, Sreeram R Cadambe, Sumalatha R Shetty
Department of Anaesthesiology, K.S. Hegde Medical Academy, Mangalore, Karnataka, India
|Date of Web Publication||23-Jun-2014|
Dr. M P Nikhil
#204, Tigris Apartments, Bunt's Hostel, Mangalore - 575 003, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Nikhil M P, Bhandary A, Cadambe SR, Shetty SR. Post-operative pulmonary embolism: Transthoracic echocardiography as a diagnostic tool. Indian J Anaesth 2014;58:362-3
|How to cite this URL:|
Nikhil M P, Bhandary A, Cadambe SR, Shetty SR. Post-operative pulmonary embolism: Transthoracic echocardiography as a diagnostic tool. Indian J Anaesth [serial online] 2014 [cited 2020 Jan 28];58:362-3. Available from: http://www.ijaweb.org/text.asp?2014/58/3/362/135097
Pulmonary embolism (PE) is a common peri-operative event with a plethora of differential diagnoses and high risk of morbidity and mortality. We report three cases of postoperative PE and discuss the importance of the use of transthoracic echocardiography for diagnosis of these events.
Case 1: A 50-year-old female developed breathlessness and tachycardia 6 h after total knee replacement. Echocardiography was performed 8 h postoperatively, which showed right atrial (RA) and right ventricular (RV) dilatation along with an increase in pulmonary artery pressure (40 mmHg). Case 2: A 30-year-old female post lower segment caesarean section presented with breathlessness on day 12. Dilated RA and RV was found on echocardiography (ECHO) performed within 2 h post-admission to Intensive Care Unit (ICU). Case 3: A 50 year old female with atrial septal defect presented with breathlessness following open cholecystectomy on postoperative day 5. ECHO performed immediately after admission to ICU showed 2 cm diameter ostium secundum ASD, dilated RA, RV and mild tricuspid regurgitation (TR).
The traditional diagnostic algorithm for PE has helical computed tomography (CT) scanning as a corner stone [Figure 1] and [Figure 2].  However, the logistics involved in ensuring a safe transport of such unstable patients can make these investigations cumbersome and impose danger to life. ECHO can provide reliable information in choosing management strategy at the bed side in such unstable patients.
Normal levels of D-dimer rule out PE.  But it may be elevated in infection, cancer, trauma, surgery making it non-specific.  Cardiac enzymes are only helpful for prognosis.  Chest X-ray can help rule out other causes. Lower limb compression ultrasonography is best used with single detector CT and prior to CT, in patients with contraindications to contrast. 
Investigations such as ventilation-perfusion (VQ) scan, pulmonary angiography and helical CT are considered better investigations for the diagnosis of PE, but usually involve transport of the patients to the imaging unit. Critically ill-patients are at increased risk of morbidity and mortality during transport.  About 45.8% adverse events rate has been noted during intra hospital transport of critically ill patients of which 26% adversely affected the patients.
Intra hospital transport has been associated with many adverse events such as desaturation (8.8%), extubation (0.4%), accidental central venous catheter removal (0.4%), hemodynamic instability (5%), increased vasopressor dose requirements(1.9%), which could adversely affect the patients. 
The latest guidelines for transport of the critically ill recommends a very long list of equipments and drug requirements to ensure safety.  The hazards during transport and the logistics involved in ensuring safety during transport can make these investigations impractical peri-operatively.
ECHO, a handy and portable tool can be a pragmatic choice peri-operatively in diagnosing PE, even though it's not the most specific modality.  It can ensure speed, accuracy, help establish a differential diagnosis and act as a guide for resuscitation. With the availability of portable ECHO machines and more personnel being familiar with ECHO, the diagnosis of PE can be achieved bedside at the earliest. Transthoracic ECHO has been shown to contribute positively to patient care in 97% of critically ill patients.
There are numerous signs and parameters described for PE on ECHO such as RV/LV area ratio, RV/LV end diastolic dimension ratio, the "McConnell" sign (RV free wall hypokinesis/akinesis along with RV apex normokinesis/hyperkinesis), interventricular septal shift ("D-sign"), pulmonary artery diameter, TR velocity, and "60/60 sign" (TR velocity <3.9 m/s plus pulmonary artery acceleration time <60 ms). RV/LV end-diastolic diameter (EDD) ratio >0.7 has been found to have good accuracy for the diagnosis of acute PE. McConnell sign is specific but not sensitive indicator of acute PE.  RV overload criteria have been found to be more sensitive and specific in the diagnosis of acute PE (the presence of 1 of four signs: (i) right-sided cardiac thrombus; (ii) RV diastolic dimension 30 mm or a RV/LV ratio 1 (iii) systolic flattening of the interventricular septum and (iv) acceleration time 90 ms or tricuspid insufficiency pressure gradient 30 mmHg in absence of RV hypertrophy).  The reported sensitivity of helical CT ranges from 53% to 100%, and specificity ranges from 81% to 100%, respectively.  ECHO performed by experienced hands can have diagnostic accuracy, matching that obtained by CT scanning.
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[Figure 1], [Figure 2]