The effects of triiodothyronine on hemodynamic status and cardiac function in potential heart donors.

Brain death is associated with altered cardiac function and low concentrations of circulating triiodothryronine (T3). However, the effects of T3 administration on hemodynamic status and cardiac function in potential heart donors remain controversial. Thirty-seven brain-dead patients were randomly and blindly allocated to receive an intravenous bolus of either 0.2 microgram/kg T3 (n = 19) or saline placebo (n = 18). Measurements included conventional hemodynamic and echocardiographic variables of cardiac volume conditions and systolic function of the left ventricle (fractional area change [FAC], velocity of myocardial fiber shortening) using a transesophageal probe, arterial and mixed venous blood gas parameters, and serum thyroid hormone concentrations. The mean concentration of T3 was 1.86 +/- 1.55 pmol/L, and only six patients (16%) had normal values of T3 in control conditions. There was no significant correlation between T3 concentration and FAC (R = 0.17, not significant). All patients receiving T3 had normalized serum T3 concentration (7.55 +/- 2.56 pmol/L) in contrast to patients receiving saline (1.48 +/- 1.26 pmol/L). No significant differences in hemodynamic and echocardiographic parameters were observed between the placebo and T3 groups. Indeed, FAC remained unchanged after T3 (44% +/- 17% vs 46% +/- 22%) or placebo (47% +/- 18% vs 50% +/- 14%) administration. In 20 patients with impaired left ventricular function (FAC < 50%), FAC remained unchanged after T3 (n = 10; 34% +/- 12% vs 30% +/- 10%) or placebo (n = 10; 38% +/- 12% vs 35% +/- 13%) administration. In 17 patients in whom organ harvesting was delayed, transesophageal echocardiography was performed 6 h later and no significant changes in FAC were noted in the T3 group (n = 8; 49% +/- 17% vs 44% +/- 17%) and the placebo group (n = 9; 51% +/- 18% vs 47% +/- 18%). In conclusion, T3 administration did not improve hemodynamic status and myocardial function in brain-dead patients, suggesting that the euthyroid sick syndrome is not the main determinant of myocardial dysfunction in these patients.

Diagnosis of traumatic mediastinal hematoma with transesophageal echocardiography.

In patients with blunt chest trauma, early diagnosis of mediastinal hematoma is important, because it could be associated with thoracic vessel injury. Mediastinal hematoma is generally evoked because of a widened mediastinum on chest radiograph, but radiologic diagnosis may lead to excessive angiography being performed. Transesophageal echocardiography (TEE) provides accurate views of the mediastinum and can be rapidly performed at the bedside. Thus, we conducted a prospective study to define TEE signs of mediastinal hematoma. TEE was performed in 22 thoracic trauma patients (trauma group) and in 20 brain-dead patients without thoracic trauma (control group). The positive diagnosis of mediastinal hematoma was made using thoracic surgery or computed tomographic scan. The specificity of TEE was 75 percent and sensitivity was 100 percent. In the trauma group, there was only one false positive but angiography discovered a traumatic aneurysm of the proximal right subclavian artery. No false negative was noted. We described three different TEE signs of mediastinal hematoma: (1) an increased distance between the probe and the aortic wall; (2) a double contour of the aortic wall; and (3) visualization of the ultrasound signal between the aortic wall and the visceral pleura. The distance between the esophageal probe and the aortic wall was the most accurate sign because it could be easily obtained; the threshold value for this distance was 3 mm. TEE appears to be an accurate method to diagnose traumatic mediastinal hematoma.

A comparison of systolic blood pressure variations and echocardiographic estimates of end-diastolic left ventricular size in patients after aortic surgery.

As suggested by experimental studies, systolic pressure variation (SPV), the difference between maximum and minimum values of systolic blood pressure after a single positive pressure breath, may be a fair indicator of left ventricular preload. SPV was quantified in 21 patients who had undergone abdominal aortic surgery and were sedated under mechanical ventilation. The aim of the study was to assess the ability of this parameter to qualitatively estimate left ventricular preload measured using transesophageal echocardiography. All patients had preoperative radionuclide ejection fraction > 45%. Postoperative mechanical ventilatory patterns were the same for all patients: tidal volume = 10 mL/kg; respiratory frequency = 12-14 breaths/min; and zero end-expiratory pressure mode. Left ventricular dimensions at end-diastole correlated well with the magnitude of both SPV (r = 0.80) and its delta down (dDown) component (i.e., the degree by which systolic pressure decreases with each mechanical breath) (r = 0.83). Once the first measurement was completed, volume loading with two increments of 250 mL of human albumin 5% was performed in all but three patients. Each volume loading step caused a significant increase in the end-diastolic area (EDa) index (7.0 +/- 1.6 to 8.5 +/- 1.6 cm2/m2) and cardiac index (CI) (3.1 +/- 0.9 to 4.1 +/- 0.9 L.min-1 x m-2) and a concomitant significant decrease in the SPV (8.6 +/- 4.5 to 6.1 +/- 3.7 mm Hg) and its dDown component (5.9 +/- 4.1 to 2.9 +/- 2 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Combined severe myocardial and pulmonary contusion: early diagnosis with transesophageal echocardiography and management with high-frequency jet ventilation: case report.

We report the case of a 27-year-old patient with blunt thoracic trauma in whom transesophageal echocardiography enabled an early diagnosis of severe myocardial contusion. Conventional mechanical ventilation dramatically enhanced cardiogenic shock because of myocardial contusion, requiring increasing doses of catecholamine. High-frequency jet ventilation produced an immediate improvement in hemodynamic status, permitting a decrease in catecholamine administration.

Early diagnosis of traumatic thoracic aortic rupture by transesophageal echocardiography.

Traumatic aorta rupture survival depends on early diagnosis requiring aortography. Aortography is the "gold standard" method, but it is time-consuming and may be dangerous in trauma patients with multiple organ injuries. Transesophageal echocardiography is a noninvasive technology that can be performed at the bedside. We report two cases in which transesophageal echocardiography enabled us to make the early diagnosis of thoracic descending aorta rupture.

Transesophageal echocardiographic assessment of left ventricular function in response to labetalol for control of postoperative hypertension.

Although labetalol (LAB), the combination of an alpha- and beta-adrenergic blocking agent, is thought to be effective and safe for the control of postoperative hypertension, no study has focused on changes in left ventricular (LV) function when this drug was used to control postoperative hypertension. Therefore, this study determined the effects of LAB on hemodynamics and LV function assessed by 2D transesophageal echocardiography (TEE) in 17 patients undergoing abdominal aortic surgery who experienced a postoperative hypertensive episode. Postoperatively, patients were transferred while still intubated and under fentanyl sedation to the postanesthesia care unit where a TEE probe was inserted to provide a short-axis view of the LV. When their systolic blood pressure increased above 165 mmHg for more than 4 minutes, LAB was given in a dose of 0.75 mg/kg IV, over 2 minutes. If the blood pressure was not lowered to within 10% of the preoperative values, additional doses of LAB were given. Control of hypertension was obtained in all patients and was associated with a significant decrease in heart rate (90 +/- 19 to 70 + 13 bpm), cardiac index (4.52 +/- 1.65 to 3.36 +/- 1.55 L/min/m2), and mixed venous oxygen saturation (73 +/- 10 to 63 +/- 10%). With the lower blood pressure, end-diastolic area increased, indicating myocardial depression. In conclusion, LAB can be used to effectively control hypertension during the early postoperative period after abdominal aortic surgery. However, the reduction of blood pressure is achieved principally by the negative inotropic effect of LAB, which predominates over its vasodilator action.

Respiratory effects of nitrous oxide during halothane or enflurane anaesthesia in children.

The respiratory effects of nitrous oxide (N2O) were studied during halothane and enflurane anaesthesia in 12 children (mean age 46.4 +/- 29.3 months, mean weight 15.3 +/- 4.2 kg) during surgery under continuous extradural anaesthesia. Four equipotent anaesthetic states were studied in random order: 1) halothane 1 MAC in oxygen, 2) halothane 0.5 MAC + 50% N2O, 3) enflurane 1 MAC in oxygen, 4) enflurane 0.5 MAC +50% N2O. End-tidal fractions of CO2 (PetCO2) and halothane and enflurane were measured using infrared analysers. The respiratory variables (tidal volume VT, minute ventilation VE, respiratory frequency F, inspiratory time Ti, mean inspiratory flow VI, effective inspiratory time Ti/Ttot) were measured using a pneumotachograph. Significant changes were observed between the four states for VE, VI, F and PetCO2, whereas the values of VT, Ti and Ti/Tot did not differ significantly. The respiratory depressant effect of 1 MAC of either halothane alone or of the mixture of halothane and N2O was very similar. During enflurane anaesthesia, PetCO2 was less increased when N2O was substituted for enflurane, owing to a significant increase in respiratory frequency. A marked decrease in VE together with an increase in PetCO2 was observed during enflurane anaesthesia (states 3 and 4) when compared to the corresponding states during halothane anaesthesia (states 1 and 2). The respiratory depressant effect of enflurane is greater than that of halothane in unpremedicated children, even when substituting N2O for an equal MAC fraction of enflurane.2+ The effect of N2O on respiratory patterns seems to depend on the inhalational agent used and/or on the vesting respiratory frequency.