Dimitrios Karakitsos

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.

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.

Acute effect of sildenafil on central hemodynamics in mechanically ventilated patients with WHO group III pulmonary hypertension and right ventricular failure necessitating administration of dobutamine

BACKGROUND/OBJECTIVESnSildenafil decreases pulmonary vascular resistance index (PVRI), in patients with pulmonary hypertension (PH). We investigated sildenafils effects on central hemodynamics of mechanically ventilated patients with WHO group-III PH and RV failure necessitating dobutamine administration.nnnMETHODSnProspective non-controlled study involving 12 (9 males, 59 ± 4 years old), patients with the above characteristics. All patients in phase-1 (days 1-2) received dobutamine (5 μg/kg/min IV). During phase-2 (days 3-6), sildenafil was started via nasogastric tube (80 mg/day) and dobutamine discontinuation was attempted. Patients were designated responders or non-responders based on whether dobutamine could be stopped or not. Phase-3 lasted from day 7 to day of weaning from mechanical ventilation; or if weaning failed, until day 20 following admission (end-of-study). Invasive and echocardiographic parameters were repeatedly recorded throughout the study.nnnRESULTSnSignificantly changed parameters (P<0.025) from baseline to phase-1, -2 and -3 (%change of mean ratios), in responders (n=7) included among others PVRI (-40%, -51%, -42%), RV stroke work index (RVSWI: 43%, 79%, 41%) and cardiac index (49%, 54%, 48%), which also differed significantly from non-responders (N=5). In phases-1 and -3 non-responders had not significant changes, in phase-2 PVRI (27%) and RVSWI (-22%) changed significantly. In contrast to non-responders, all responders were weaned from mechanical ventilation until the end-of-study (P<0.025).nnnCONCLUSIONSnSildenafil may improve central hemodynamics and RV function indices in ventilated patients with WHO group-III PH and RV failure requiring dobutamine infusion, when they respond favorably to the latter. Accordingly, an adequate RV systolic reserve may be mandatory for sildenafil to exert its actions.

Comparative study of flow in right-sided and left-sided aortas: numerical simulations in patient-based models

A right-sided aorta is a rare malformation which may be associated with other various types of congenital heart disease. We utilised haemodynamic, echocardiographic measurements, computerised tomography and image reconstruction software packages that were integrated in a computational fluid dynamics model to determine blood flow patterns in patient-based aortas. In the left-sided aorta, a systolic clockwise rotational component was present, while helical flow was depicted in the aortic arch that was converted in the descending aorta as counter-rotating vortices with accompanying retrograde flow. The right-sided configuration has not altered the orientation of the three-dimensional vortex, but intensification of polymorphic flow patterns, alterations in wall shear stress distribution and development of a lateral pressure gradient at the area of an aneurysmal anomaly was observed. Moreover, increments of Reynolds, Womersley and Dean numbers were evident. These phenomena along with the formation of the aneurysm might influence cardiovascular risk in patients with right-sided aortas.

Ultrasound-guided subclavian and axillary vein cannulation via an infraclavicular approach: In the tradition of Robert Aubaniac.

Crit Care Med 2012 Vol. 40, No. 10 DOI: 10.1097/CCM.0b013e31825f78c3 allows measurement of changes in the perfusion of the renal cortical microcirculation which, experimentally, parallel changes in clearance measurements of renal plasma flow in humans (5). To conclude, we believe that CPCMRI is a powerful technique that complements both standard and contrastenhanced ultrasound assessment of the renal circulation and may enable a better understanding the physiological meaning of these measurements in differing clinical contexts. As well as being a primary investigatory modality, CPC-MRI could provide an invaluable method to calibrate and validate ultrasound techniques, including contrast-enhanced ultrasonography, which might be more widely applicable in clinical practice. The authors have not disclosed any potential conflicts of interest.

Risk Factors for Acute Adverse Events During Ultrasound-guided Central Venous Cannulation in the Emergency Department: CORRESPONDENCE

We read with interest the article published in your journal by Theodoro et al. regarding the identification of risk factors for acute adverse events surrounding ultrasound (US)-guided central venous cannulation. We strongly agree with the authors that both patient and operator factors exist and clearly influence the frequency of adverse events during the procedure. Early recognition of these factors may be of importance, especially in the emergency department (ED), as the placement of central venous catheters (CVCs) in emergency settings is rather different compared to the routine CVC placement in the intensive care unit. However, questions regarding the methods used in this study can be raised. The authors do not explain whether the shortor the long-axis approach for cannulation was preferred and if the US operators were able to visualize the needle and ⁄ or the needle tip while cannulating (in-plane technique). Using an out-of-plane technique is potentially dangerous, as it is possible to cause inadvertent posterior vessel wall penetration or damage of adjacent anatomical structures, resulting in mechanical complications such as pneumothorax, hemothorax, hematomas, arteriovenous fistulas, and nerve injuries. Thus, we wonder to what extent technical competence can influence the recorded frequency of adverse events during US-guided catheterization. Moreover, the total number of attempts and needle passes was not recorded in the study. This may be of importance as the former has been suggested as a risk factor for both mechanical and infectious complications in previous series. The authors found that patient history of dialysis was associated with adverse events during US-guided internal jugular cannulation. They also emphasized that when visualized with US, an engorged central vein due to a distal stricture or thrombus may appear to be an easy target. We note that in end-stage renal disease patients, it is always a prudent strategy to visualize the target vessel throughout its full course, as thrombosis and ⁄ or obstruction may be present due to a patent or a nonpatent arteriovenous fistulae. Hence, the use of US before the cannulation is rather mandatory in this case, as long as the physician who is performing the procedure is familiar with basic principles of vascular US. These patients should undergo routine evaluation of their vascular system irrespective of other procedures and before cannulation, especially if there is no previous record of a vascular evaluation. The fact that Theodoro et al. found that risk factors such as obesity, hyperinflation, and coagulopathy were not associated with acute adverse events during the US-guided procedure underlines the clear benefit of US guidance especially in acutely ill patients, when there is an urgency to perform catheterization in suboptimal and life-threatening conditions. Finally, due to the obvious inherent limitations of this prospective observational study, a comparison with the landmark technique was not feasible; hence no safe conclusions can be drawn. It would be quite interesting to compare the variables associated with an adverse event between the landmark and the US-guided techniques. doi: 10.1111/j.1553-2712.2011.01021.x

Invasive and Ultrasound Based Monitoring of the Intracranial Pressure in an Experimental Model of Epidural Hematoma Progressing towards Brain Tamponade on Rabbits

Introduction. An experimental epidural hematoma model was used to study the relation of ultrasound indices, namely, transcranial color-coded-Doppler (TCCD) derived pulsatility index (PI), optic nerve sheath diameter (ONSD), and pupil constriction velocity (V) which was derived from a consensual sonographic pupillary light reflex (PLR) test with invasive intracranial pressure (ICP) measurements. Material and Methods. Twenty rabbits participated in the study. An intraparenchymal ICP catheter and a 5F Swan-Ganz catheter (SG) for the hematoma reproduction were used. We successively introduced 0.1 mL increments of autologous blood into the SG until the Cushing reaction occurred. Synchronous ICP and ultrasound measurements were performed accordingly. Results. A constant increase of PI and ONSD and a decrease of V values were observed with increased ICP values. The relationship between the ultrasound variables and ICP was exponential; thus curved prediction equations of ICP were used. PI, ONSD, and V were significantly correlated with ICP (r 2 = 0.84 ± 0.076, r 2 = 0.62 ± 0.119, and r 2 = 0.78 ± 0.09, resp. (all P < 0.001)). Conclusion. Although statistically significant prediction models of ICP were derived from ultrasound indices, the exponential relationship between the parameters underpins that results should be interpreted with caution and in the current experimental context.

Venous Imaging for Reflux Using Duplex Ultrasonography

Chronic venous disease is very prevalent and has significant socioeconomic impact in the society. After physical examination is performed duplex ultrasound (DU) has become the method of choice for evaluating venous disease. This is because it is noninvasive, portable, easily repeatable, has great resolution, evaluates anatomy and function, offers very good differential diagnosis, and has relatively low cost. DU examination should be performed with the patient in the standing position to increase its diagnostic yield. Cutoff values for venous reflux have been established and generally accepted with a retrograde flow of >500 ms for superficial, deep calf veins, deep femoral, and perforator veins and >1,000 ms for common femoral, femoral, and popliteal veins. Anatomic variations in both the superficial and deep venous systems are very common (i.e., duplication of the popliteal or femoral vein, hypoplasia of the great saphenous vein); hence, careful examination is mandatory. Segmental reflux has a mild to moderate clinical presentation, while extensive involvement is associated with skin changes. Around 80% of patients with chronic venous disease have reflux alone, 17% have reflux and obstruction, while obstruction alone is uncommon. The combination of reflux and obstruction has usually the worst prognosis. Site-specific DU examination is important in tailoring therapeutic interventions according to pertinent findings. DU is important for obtaining venous access, performing endovenous ablation, foam sclerotherapy, while it can also be useful for vein angioplasty and stenting, insertion of inferior vena cava filters, and guide thrombolysis. The introduction of intravascular ultrasound has facilitated the development of strategies to overcome limitations of ultrasound technology. Examination of lower extremities can be challenging especially in obese patients, in the presence of edema, while inability of the patient to cooperate during the examination can impact the quality of testing. Despite these limitations, DU remains the standard of care in detecting vein disease.

Ultrasound Imaging in Vascular Diseases

Mariantina Fragou1, Andreas Karabinis2, Eugene Daphnis3, Nicolaos Labropoulos4 and Dimitrios Karakitsos1 1Department of Intensive Care Unit, General State Hospital of Athens 2Department of Intensive Care Unit, Onassis Cardiac Surgery Center, Athens 3Nephrology Department, Heraklion University Hospital, Heraklion, Crete 4Department of Surgery, Stony Brook University Medical Center, Stony Brook NY 1,2,3Greece 4USA