DK2985_C000 1..28 - AlSharqia Echo Club

564 Transesophageal Echocardiographyfor further exploration or a change in the surgical procedure.The removal of cardiac masses is a category IIindication for intraoperative TEE.G. Detection of Foreign BodiesThe ability of intraoperative TEE to locate bullet fragments,mobile calcium plaques (see Chapter 16, Fig. 16.17) andmedical devices (e.g. catheter fragments) is reported, butthere is no evidence regarding its impact on clinical outcomes.The yield of intraoperative TEE in detectingforeign bodies is likely to be low in most settings, but itmay have greater utility at centers with a high incidenceof gunshot injuries. The detection of foreign bodies is acategory II indication for intraoperative TEE.H. Detection of Air Emboli DuringCardiotomy, Heart Transplant,and Upright NeurosurgicalProceduresIntraoperative TEE can detect air bubbles in 8–60% ofpatients undergoing neurosurgery and 11–79% of patientsundergoing cardiac surgery (see Chapter 9, Fig. 9.42).Current evidence is inadequate, however, to determinewhether these emboli increase the risk of neurologic complicationsor whether intraoperative TEE monitoring forair emboli improves clinical outcomes.Transesophageal echocardiography is an extremelysensitive test for air (bubbles as small as 2 mm usuallycan be detected) but the clinical significance of thesebubbles is unclear. Animal studies suggest that air entrainment.1 cm 3 /kg increases the risk of neurologic complications,but the threshold value for safe air volumes inhumans is uncertain. The task force believes that patientsbenefit when TEE detects air during cardiotomy and neurosurgicalprocedures (12). During cardiotomy, ventingprocedures before cessation of CPB can eliminate retainedair, and the task force believes that such measures decreasethe patient’s risk of embolic neurologic events, right ventricularfailure due to right coronary artery embolization(see Chapter 16, Fig. 16.18) and myocardial ischemia.Transesophageal echocardiography offers similar benefitsduring sitting craniotomies, especially if the patientshave not been screened preoperatively for patentforamen ovale (12). Patent foramen ovale appears to bea risk factor for stroke, and intraoperative maneuvers caninduce intracardiac pressure changes that open probepatentdefects to permit paradoxical emboli.Transesophageal echocardiography is the only intraoperativetool for detecting these abnormalities; few othertests can detect air and sources of right-to-left shunt asaccurately. Use of TEE during upright neurosurgicalprocedures may increase the risk of vocal cord injury,although this risk may be reduced by proper techniqueand equipment (31).The detection of air emboli during cardiotomy andheart transplant is a category II indication for using intraoperativeTEE. It should also be considered for patientsundergoing upright neurosurgical procedures (category II).I. Intracardiac ThrombectomyIntraoperative TEE can detect intracardiac thrombi in2–10% of patients undergoing cardiac surgery, oftenexposing thrombi that were not apparent on preoperativeTTE, but there is little evidence beyond case reports thatthe detection or evacuation of these clots results inimproved clinical outcomes (see Chapter 23, Fig. 23.31).In patients scheduled for thrombectomy, a pre-CPBechocardiographic examination can prevent an unnecessaryoperation if it determines that the thrombus has alreadyembolized. Intracardiac thrombectomy is a category IIindication for pre-CPB TEE.J. Pulmonary EmbolectomyCase reports have described the use of perioperative TEEto detect pulmonary emboli and evaluate treatment, butthere is little evidence regarding its impact on clinicaloutcomes.The task force (1996) believes that perioperative TEE isespecially useful during pulmonary embolectomy to evaluatehemodynamic status and detect residual emboli. Theopinion of the task force, based on perioperative TEEmonitoring, is that 30% of embolectomy proceduresfail to remove all emboli completely. These residualemboli are potentially harmful to the patient and the useof TEE to detect them intraoperatively may therefore bebeneficial (12).Transesophageal echocardiography may also be usefulto determine the cause of acute hemodynamic disturbances,such as those resulting from pulmonary emboli, but itis not necessary for all patients with known or suspectedpulmonary emboli (see Chapter 9, Fig. 9.40). Pulmonaryembolectomy is a category II indication for using TEE.K. Suspected Cardiac TraumaThe role of intraoperative and postoperative TEE indetecting unrecognized traumatic injuries to the hearthas been described, but there is otherwise little evidencethat TEE improves the clinical outcome of cardiactrauma patients (12).Routine use of TEE for evaluating cardiac trauma ispredicated on the availability of TEE equipment andqualified staff at trauma units. Unsuspected injuriescould be detected during surgery if TEE is performed