Theodosios Saranteas

Real-time ultrasound-guided subclavian vein cannulation versus the landmark method in critical care patients: A prospective randomized study*

Objective:Subclavian vein catheterization may cause various complications. We compared the real-time ultrasound-guided subclavian vein cannulation vs. the landmark method in critical care patients. Design:Prospective randomized study. Setting:Medical intensive care unit of a tertiary medical center. Patients:Four hundred sixty-three mechanically ventilated patients enrolled in a randomized controlled ISRCTN-registered trial (ISRCTN-61258470). Interventions:We compared the ultrasound-guided subclavian vein cannulation (200 patients) vs. the landmark method (201 patients) using an infraclavicular needle insertion point in all cases. Catheterization was performed under nonemergency conditions in the intensive care unit. Randomization was performed by means of a computer-generated random-numbers table and patients were stratified with regard to age, gender, and body mass index. Measurements and Main Results:No significant differences in the presence of risk factors for difficult cannulation between the two groups of patients were recorded. Subclavian vein cannulation was achieved in 100% of patients in the ultrasound group as compared with 87.5% in the landmark one (p < .05). Average access time and number of attempts were significantly reduced in the ultrasound group of patients compared with the landmark group (p < .05). In the landmark group, artery puncture and hematoma occurred in 5.4% of patients, respectively, hemothorax in 4.4%, pneumothorax in 4.9%, brachial plexus injury in 2.9%, phrenic nerve injury in 1.5%, and cardiac tamponade in 0.5%, which were all increased compared with the ultrasound group (p < .05). Catheter misplacements did not differ between groups. In this study, the real-time ultrasound method was rated on a semiquantitative scale as technically difficult by the participating physicians. Conclusions:The present data suggested that ultrasound-guided cannulation of the subclavian vein in critical care patients is superior to the landmark method and should be the method of choice in these patients.

Thyroid hormone receptors α1 and β1 are downregulated in the post-infarcted rat heart: consequences on the response to ischaemia-reperfusion

There is accumulating evidence that thyroid hormone metabolism is altered after myocardial infarction (AMI) but its physiological relevance remains largely unknown. The present study investigated the possible role of thyroid hormone signaling in the response of the post-infarcted heart to ischaemia-reperfusion. Wistar rats were subjected to left coronary artery ligation (AMI), or sham operation (SHAM). After 8 weeks, hearts from AMI and SHAM rats were perfused in Langendorff mode and subjected to 20 min of zero-flow global ischaemia (I) and 45 min of reperfusion (R); AMI(I/R), n = 7 and SHAM(I/R), n = 7. Basal left ventricular pressure (LVDP), +dp/dt, and –dp/dt were significantly reduced. Left ventricular weight of the viable myocardium was increased by 14% in the AMI as compared to SHAM hearts, P < 0.05. T3 and T4 plasma levels in nM were 1.83 (0.08) and 53.3 (2.9) for SHAM and 1.76 (0.06) and 59.4 (5.2) for AMI rats, respectively, P > 0.05. TRα1 and TRβ1 expression levels were 1.3- and 1.8-fold less in AMI than in SHAM hearts, P < 0.05. Furthermore, SERCA and NHE1 expression levels were 2.1- and 1.8-fold less in AMI than in SHAM, P < 0.05. PKCε was 1.35-fold more in AMI compared to SHAM, P < 0.05. Myocardial glycogen content (in µmol/g) was 7.8 (1.2) in AMI as compared to 4.4 (0.5) for SHAM hearts, P < 0.05. After I/R, left ventricular end-diastolic pressure at 45 min of R (LVEDP45 in mmHg) was 20.3 (3.2) for AMI(I/R) vs 50.6 (4.8) mmHg for SHAM(I/R), P < 0.05. LDH release per gram of tissue was 251 (103) for AMI(I/R) and 762 (74) for SHAM(I/R), P < 0.05. In conclusion, TRα1 and TRβ1 are downregulated after myocardial infarction and this was associated with altered expression of thyroid hormone responsive genes and increased tolerance of the post-infarcted heart to ischaemia-reperfusion injury.

Anatomy and clinical implications of the ultrasound-guided subsartorial saphenous nerve block.

Background: We evaluated the anatomic basis and the clinical results of an ultrasound-guided saphenous nerve block close to the level of the nerves exit from the inferior foramina of the adductor canal. Methods: The anatomic study was conducted in 11 knees of formalin-preserved cadavers in which the saphenous nerve was dissected from near its exit from the inferior foramina of the adductor canal. The clinical study was conducted in 23 volunteers. Using a linear probe, the femoral vessels and the sartorius muscle were depicted in short-axis view at the level where the saphenous nerve exits the inferior foramina of the adductor canal. Ten milliliters of 1.5% lidocaine was injected into the compartment structured by the sartorius muscle and the femoral artery. Results: The saphenous nerve was found to exit the adductor canal from its inferior foramina in 9 (81.8%) of 11 and at a more proximal level in 2 (18.2%) of 11 of the anatomic specimens. In a single specimen (9%), the saphenous nerve was formed by the anastomosis of 2 branches. In all the dissections, the saphenous nerve, after exiting the adductor canal, passed between the sartorius muscle and the femoral artery. Of the 23 volunteers, 22 responded with a complete sensory block, whereas a single volunteer demonstrated no sensory blockade. None of the volunteers experienced a motor block of the hip flexors and knee extensors. Conclusions: Ultrasound-guided injection directly caudally from the inferior foramina of the adductor canal, between the sartorius muscle and the femoral artery, seems to be an effective approach for saphenous nerve block.

Time-dependent changes in the expression of thyroid hormone receptor α1 in the myocardium after acute myocardial infarction: possible implications in cardiac remodelling

The present study investigated whether changes in thyroid hormone (TH) signalling can occur after acute myocardial infarction (AMI) with possible physiological consequences on myocardial performance. TH may regulate several genes encoding important structural and regulatory proteins particularly through the TR alpha 1 receptor which is predominant in the myocardium. AMI was induced in rats by ligating the left coronary artery while sham-operated animals served as controls. This resulted in impaired cardiac function in AMI animals after 2 and 13 weeks accompanied by a shift in myosin isoforms expression towards a fetal phenotype in the non-infarcted area. Cardiac hypertrophy was evident in AMI hearts after 13 weeks but not at 2 weeks. This response was associated with a differential pattern of TH changes at 2 and 13 weeks; T(3) and T(4) levels in plasma were not changed at 2 weeks but T(3) was significantly lower and T(4) remained unchanged at 13 weeks. A twofold increase in TR alpha 1 expression was observed after 13 weeks in the non-infarcted area, P<0.05 versus sham operated, while TR alpha 1 expression remained unchanged at 2 weeks. A 2.2-fold decrease in TR beta 1 expression was found in the non-infarcted area at 13 weeks, P<0.05, while no change in TR beta 1 expression was seen at 2 weeks. Parallel studies with neonatal cardiomyocytes showed that phenylephrine (PE) administration resulted in 4.5-fold increase in the expression of TR alpha 1 and 1.6-fold decrease in TR beta 1 expression versus untreated, P<0.05. In conclusion, cardiac dysfunction which occurs at late stages after AMI is associated with increased expression of TR alpha 1 receptor and lower circulating tri-iodothyronine levels. Thus, apo-TR alpha 1 receptor state may prevail contributing to cardiac fetal phenotype. Furthermore, down-regulation of TR beta 1 also contributes to fetal phenotypic changes. alpha1-adrenergic signalling is, at least in part, involved in this response.

Cardiac and central vascular functional alterations in the acute phase of aneurysmal subarachnoid hemorrhage

Objectives:To investigate aortic functional alterations in the acute phase of aneurysmal subarachnoid hemorrhage and to evaluate the relationship between potential cardiovascular alterations and delayed cerebral infarctions or poor Glasgow Outcome Scale score at discharge from critical care unit. Design:Prospective observational study. Setting:Critical Care Departments of two tertiary centers. Patients:Thirty-seven patients with aneurysmal subarachnoid hemorrhage. Interventions:Patients were evaluated at two time points: on admission (acute aneurysmal subarachnoid hemorrhage phase) and at least 21 days later (stable aneurysmal subarachnoid hemorrhage state). At baseline, the severity of aneurysmal subarachnoid hemorrhage was assessed clinically (Hunt and Hess scale) and radiologically (brain computed tomography Fisher grading). Aortic elasticity was evaluated by Doppler-derived pulse-wave velocity and left ventricular function by echocardiography. Serum B-type natriuretic peptide and troponin I were also assessed at the same time points. Measurements and Main Results:At the acute phase, 23 patients (62%) were found to present supranormal pulse-wave velocity and 14 patients (38%) presented left ventricular systolic dysfunction; there were significant associations between pulse-wave velocity values and left ventricular ejection fraction (p < .001). Left ventricular ejection fraction and pulse-wave velocity were both associated with Hunt and Hess (p ⩽ .004) and Fisher grading (p ⩽ .03). Left ventricular ejection fraction and pulse-wave velocity were improved between acute aneurysmal subarachnoid hemorrhage and stable state (p ⩽ .005); changes (&Dgr;%) were greater in patients who initially had regional wall motion abnormalities compared to patients who had not (28.7% ± 10.2% vs. 2.4% ± 1.8% [p = .002] and −17.9% ± 3.7% vs. −3.5% ± 4.7% [p = .045], respectively). Pulse-wave velocity/left ventricular ejection fraction ratio was the only independent predictor for delayed cerebral infarctions. Left ventricular ejection fraction, B-type natriuretic peptide, pulse-wave velocity, and pulse-wave velocity/left ventricular ejection fraction showed significant diagnostic performance for predicting delayed cerebral infarctions or poor Glasgow Outcome Scale score (1–3). Conclusions:Our findings suggest that significant cardiovascular alterations in left ventricular function and in aortic stiffness occur during the early phase of aneurysmal subarachnoid hemorrhage. These phenomena were associated with adverse outcomes in this study and their role in the pathogenesis of delayed neurologic complications warrants further investigation.

Thoracic paravertebral spread using two different ultrasound‐guided intercostal injection techniques in human cadavers

The continuity between the intercostal and paravertebral space has been established by several studies. In this study, the paravertebral spread of a colored dye was attempted with two different ultrasound‐guided techniques. The posterior area of the trunk was scanned with a linear probe between the level of the fifth and the seventh thoracic vertebrae in eleven embalmed human cadavers. In the first technique, the probe was placed transversely below the inferior margin of the rib, and a needle was inserted between the internal intercostal membrane and the pleura. In the second technique, the probe was placed longitudinally at the intercostal space 5 cm lateral to the spinous processes, and the needle was inserted between the internal intercostal membrane and the pleura. In both techniques, 1 ml of methylene blue was injected, and both the intercostal and paravertebral spaces were prepared. In total, 33 injections were performed: 19 with the transverse technique and 14 with the longitudinal technique. Successful spread of the dye to the thoracic paravertebral space was recorded in 89.5% cases using the transverse technique and 92.8% cases using the longitudinal technique. No intrapleural spread of the dye was recorded in either technique. Ultrasound‐guided injection into the intercostal space may offer an alternative approach to the thoracic paravertebral space. Clin. Anat. 23:840–847, 2010.

Transthoracic echocardiography for the diagnosis of left ventricular thrombosis in the postoperative care unit

IntroductionTransthoracic echocardiography (TTE) is a reliable, noninvasive imaging method that is useful in the evaluation of cardiovascular thrombosis. We conducted a retrospective study of all the echocardiograms from patients in the postoperative care unit to assess the role of TTE in thrombus identification in the left ventricle.MethodsThis retrospective database evaluation included all echocardiograms during a 14-month period. The echocardiographic examination protocol included the subcostal four-chamber view, the apical four-chamber view, the apical two-chamber view and the parasternal view, along the long and short axes in both spontaneously and mechanically ventilated patients. All echocardiograms were obtained within the 48 hours immediately following surgery.ResultsIn total, 160 postoperative echocardiograms were obtained from 160 patients and resulted in the detection of five cases of left ventricular thrombosis. Subgroup analysis showed that 21 and 35 of the 160 patients examined had either dilated or ischemic cardiomyopathy, respectively. In these patients, preoperative echocardiograms had been obtained recently prior to surgery and were negative for left ventricular thrombus. In three of 35 patients with ischemic cardiomyopathy and two of 21 patients with dilated cardiomyopathy, thrombus was identified in the left ventricle. The thrombi were mobile, uncalcified and pedunculated and were located in the apex of the left ventricle. In addition, no clinical consequences of the left ventricular thrombi were recorded.ConclusionsLow-flow conditions in heart chambers due to ischemic or dilated cardiomyopathy in conjunction with the hypercoagulability caused by perioperative prothrombotic factors may lead to thrombotic events in the left ventricle.

Limitations and Technical Considerations of Ultrasound-Guided Peripheral Nerve Blocks: Edema and Subcutaneous Air

Objective: Despite advantages of ultrasound‐guided peripheral nerve blocks as compared with established techniques, various limitations may exist. We present 2 trauma patients in whom the usefulness of ultrasound techniques was limited by edema and subcutaneous air. Case Report: Two male patients were admitted to the Intensive Care Unit due to multiple trauma. In the first patient, tissue edema and obesity (body mass index, calculated as weight [kg]/height [m2] = 35), and in the second patient, subcutaneous emphysema, were significant limitations for the application of ultrasound‐guided peripheral nerve blocks. These factors made 2‐dimensional ultrasound imaging difficult despite the use of tissue harmonic technique and advanced ultrasound equipment. Neurostimulation technique alone, or combined with ultrasound imaging eventually led to successful nerve block. Conclusions: Ultrasound technique limitations do exist. We present 2 conditions, edema and subcutaneous air, which contributed to ultrasound failure to provide a clear image of the targeted nerves.

Transesophageal echocardiography and vascular ultrasound in the diagnosis of catheter-related persistent left superior vena cava thrombosis

We refer to a very rare case of catheter-related thrombosis in a trauma patient with persistent left and absent right superior vena cava. The role of ultrasound examination in the early diagnosis and treatment of thrombosis in the setting of intensive care unit (ICU) is thoroughly discussed. A 30-year-old man was admitted to the ICU due to multiple trauma. Six days after right internal jugular vein (IJV) catheter insertion, and during a vascular ultrasound examination, an IJV catheter-related thrombosis was diagnosed. Hence, the catheter was removed, and a follow-up ultrasound examination revealed thrombus remnant in the IJV extended into brachiocephalic vein. Subsequently, to exclude a possible extension of the thrombus in the superior vena cava, a transesophageal echocardiography (TEE) examination was performed. The latter revealed a distended coronary sinus and the presence of persistent left superior vena cava (PLSVC). Additionally, TEE examination disclosed thrombus remnant within the PLSVC that was also confirmed with CT venography. Anticoagulant therapy was started thus preventing major complications such as coronary sinus obstruction. This case underlines the role of cardiovascular ultrasound examination as an important tool in performing variety of monitoring in the setting of the ICU.

Prospective randomized comparison between ultrasound-guided saphenous nerve block within and distal to the adductor canal with low volume of local anesthetic

Background and Aims: The anatomic site and the volume of local anesthetic needed for an ultrasound-guided saphenous nerve block differ in the literature. The purpose of this study was to examine the effect of two different ultrasound-guided low volume injections of local anesthetic on saphenous and vastus medialis nerves. Materials and Methods: Recruited patients (N = 48) scheduled for orthopedic surgery were randomized in two groups; Group distal adductor canal (DAC): Ultrasound-guided injection (5 ml of local anesthetic) distal to the inferior foramina of the adductor canal. Group adductor canal (AC): Ultrasound-guided injection (5 ml local anesthetic) within the adductor canal. Following the injection of local anesthetic, block progression was monitored in 5 min intervals for 15 min in the sartorial branches of the saphenous nerve and vastus medialis nerve. Results: Twenty two patients in each group completed the study. Complete block of the saphenous nerve was observed in 55% and 59% in Group AC and DAC, respectively (P = 0.88). The proportion of patients with vastus medialis weakness at 15 min in Group AC, 36%, was significantly higher than in Group DAC (0/22), (P = 0.021). Conclusions: Low volume of local anesthetic injected within the adductor canal or distally its inferior foramina leads to moderate success rate of the saphenous nerve block, while only the injection within the adductor canal may result in vastus medialis nerve motor block.