Doppler Monitoring Research Articles

The clinical significance of microembolic signals in patients with systemic lupus erythematosus

Background: Microembolic signals (MES) have been found in about 10% of patients with systemic lupus erythematosus (SLE), and have been associated with neuropsychiatric manifestations (NPSLE), including cerebrovascular damage.Objective: To determine the frequency of MES in patients with SLE, previous and further risk of neuropsychiatric manifestations.Methods: One hundred and nine consecutive patients with previous diagnosis of SLE and without acute neurological manifestations were evaluated clinically and by transcranial Doppler monitoring (1 hour) from November 2002 to March 2003. The baseline characteristics and outcomes were compared between patients with and without MES. Patients were followed during a mean time of 4·5 years, to detect the appearance of NPSLE, including stroke and transient ischemic attacks.Results: MES were detected in 16 patients (14·7%; range: 3-64/h); at baseline, previous neuropsychiatric manifestations were more frequent in patients with MES: 12/16 (75%) versus 46/92 (50%) (p = 0·064), especially for cognitive dysfunction (p = 0·036). Antiphospholipid syndrome and cardiovascular risk factors did not differ between groups at baseline and follow-up, neither the proportion of patients on antiplatelet agents. At follow-up, two patients from the MES positive group and six from the MES negative group developed a new neuropsychiatric manifestation (p = not significant).Conclusion: This study supports an association of MES and a history of NPSLE, especially cognitive dysfunction. MES were not associated with an increased risk of cerebral ischemia and other neurological manifestations at follow-up.

Transcranial microbubble destruction by using re‐focusing ultrasound.

Administration of microbubbles (MBs) during transcranial Doppler monitoring further accelerates ultrasound‐enhanced thrombolysis. However, low efficiency of transcranial ultrasound transmission resulting from phase aberrations through skull is still an obstacle. To alleviate this, re‐focusing by phase aberration correction using echoes from microbubbles can be performed. Two re‐focusing methods were designed for transcranial MB destruction. One is adjusting the emission phases derived from the channel‐to‐channel correlation of received signals. The other is simply adjusting the transmit focal depth. This is possible because the phase aberrations typically result in approximately parabolic delay errors. Focusing quality was compared using finite difference time domain simulations, and the mechanical index (MI) distributions were calculated as indices for likelihood of microbubble destruction. Using the correlation based methods, the beamwidth becomes 45.5% narrower than that by using the time reversal method. The MI can also be increased by 15.9% while keeping it under safety range. Adjusting the transducer position, on the other hand, can also enhance the focusing efficiency and improve efficiency of ultrasound‐enhanced thrombolysis. It is also easy to implement using current clinical systems.

Reperfusion Therapies for Acute Ischemic Stroke

Ischemic stroke is most often caused by an acute extracranial or intracranial thromboembolic lesion obstructing an artery. It has been demonstrated that recanalization is the most important modifiable predictor of a good clinical outcome. Reperfusion strategies focus on early reopening of the vessel to reestablish antegrade flow within the penumbra.Current standard therapy within 4.5h is intravenous thrombolysis (IVT) with tissue plasminogen activator (tPA, 0.9mg/kg body weight, maximum dose 90mg). Thrombolytic therapy appears to be safe and effective across various types of hospitals, if the treatment is conducted by a physician with stroke expertise.New imaging methods (MR diffusion/perfusion, CT perfusion) are being investigated in order to better select patients who are most likely to benefit from recanalization therapy based on current clinical evidence. Neither perfusion imaging with CT or MR nor the mismatch concept are recommended for routine treatment decisions within or beyond the 4.5h available for IVT.If major vessel occlusion is proven but IVT is contraindicated, intra-arterial thrombolysis (IAT) with tPA or mechanical thrombectomy with the Merci Retriever or Penumbra System may be a treatment option. The availability of IAT generally should not preclude the intravenous administration of tPA in otherwise eligible patients. Intra-arterial treatment can be performed within 8h after stroke onset. Combining intravenous tPA pretreatment with subsequent IAT or mechanical thrombectomy may improve the recanalization rate and may be used as a rescue therapy in cases of persistent major vessel occlusion after unsuccessful IVT.Despite testing, no thrombolytic agent other than tPA (e.g., IIb/IIIa antagonists, heparin, etc.) has yet been approved for routine practice for either intravenous or intra-arterial application, alone or in combination with tPA.Continuous transcranial Doppler (TCD) monitoring of an occluded vessel may increase the rate of early recanalization after tPA; this effect may be facilitated by the administration of microbubbles. This method is still considered experimental.

Diagnostic Criteria and Yield of Real-Time Transcranial Doppler Monitoring of Intra-Arterial Reperfusion Procedures

Intra-arterial (IA) rescue procedures are increasingly used to treat acute ischemic stroke. We implemented continuous transcranial Doppler (TCD) monitoring during these procedures to detect any potentially harmful flow changes. Here, we report diagnostic criteria and yield of TCD monitoring. We studied consecutive acute stroke patients who underwent IA reperfusion procedures. TCD flow signatures during these procedures were analyzed and any abnormal findings were documented. Patients were included only if there was successful insonation through the skull; of 56 eligible patients, 51 were included. IA procedures included IA tissue plasminogen activator, use of the Merci retriever, the Penumbra system, balloon angioplasty, and stenting. On TCD monitoring, contrast injections produced high-intensity signals and increased the mean flow velocity (MFV). Deployment of the Merci device appeared as high-intensity, short-duration signals with a transient MFV decrease of 11.5%. The Penumbra system produced lower-intensity signals with a greater transient decrease in MFV during aspiration. IA tissue plasminogen activator significantly increased MFV by 7.5% over Merci and Penumbra flow velocity changes. Power motion Doppler-TCD detected reocclusion in 13 patients, artery-to-artery embolization in 2 patients, air embolism in 2 patients, and hyperperfusion in 6 patients. Overall, the yield of TCD monitoring was positive in 23 (49%) patients who received IA reperfusion procedures. Our velocity, intensity, and flow signatures criteria for TCD monitoring of IA reperfusion procedures detect reocclusion, hyperperfusion, or thromboembolism and air embolism in nearly half of all procedures. This hemodynamic information can be particularly helpful when neurological assessment is limited or delayed.

Aortic Arch Catheterization during Transfemoral Carotid Artery Stenting: an Underestimated Source of Cerebral Emboli

Cerebral embolization is still a major concern in patients undergoing transfemoral carotid artery stenting. Intraoperative transcranial Doppler (TCD) monitoring and diffusion-weighted magnetic resonance imaging (DW-MRI), two techniques currently used to study this phenomenon, have provided data suggesting the importance of aortic arch catheterization in determining the overall embolic load observed during this procedure. In order to reduce this cerebral embolization, some Authors have proposed the performance of carotid artery stenting through a cervical access, either surgical or percutaneous. We review in this article the available TCD and DW-MRI data supporting transcervical CAS, along with its clinical results.

TCDモニタリングを参考に治療を行った頚部内頚動脈解離の2症例

Cervical internal carotid artery dissection causes ischemic stroke in young patients. There is no evidence to clearly indicate whether antithrombotic therapy is effective in such patients.We treated two patients who suffered ischemic events due to cervical internal carotid artery dissection. Both patients underwent transcranial Doppler (TCD) monitoring of the ipsilateral middle cerebral artery. No high-intensity transient signals (HITS) were detected in either case. Therefore we did not perform antithrombotic therapy and there was no recurrence. TCD monitoring may indicate whether antithrombotic therapy is necessary or not.

Woman with surgical reconstruction of anal atresia who realized pregnancy with in vitro fertilisation

Anal atresia is a congenital anomaly, very life-threatening and urgent. Surgical treatment of this anomaly consists of colostomy first, and then of anal reconstruction. We presented a 31-year old female with the surgery treatment of anal atresia in the early childhood. In the reproductive period, due to tubal infertily, the patient was included in the program of in vitro fertilization (IVF), in the Clinic for Gynecology and Obstetrics "Narodni front", Belgrade. Within this program a long protocol of ovarian stimulation was performed. Ultrasonographic and color Doppler monitoring of the patient was applied by the use of an ultrasonographic apparatus type Siemens Acuson X 150, while any hormonal examinations were performed by an Architect Abbott unit. During the IVF program, the growth of follicules was controlled by the use of ultrasonography, microcirculation of the ovaries and the uterus was marked by a power-pulsating color Doppler, and hormonal examination was performed starting from the day of stimulation up to the day of injecting Pregnyl. The patient was administered Suprefact (buserelin) sc from the 21st day of the menstrual cycle, as well as from the 3rd day of the cycle, for totally 11 days. The patient was given 29 ampoules of Gonal F (recombinant human FSH) 75 IJ im and 15 ampoules of Menopur (menotrophin) im. Due to a modified pelvic anatomy, the left ovary aspiration was disabled, while the right ovary aspired seven oocytes successfully. Three embryos were inserted in the uterus. The delivery was performed by cesarean section. In the reported patient with a modified pelvic anatomy due to four corrective surgeries of anal atresia, and tubal infertility in the reproductive period, the method of choice for the realization of pregnancy was the IVF procedure. The realized pregnancy and the delivery could be considered highly successful in regard to possible risks.

Cerebral Emboli Generation during Off-Pump Coronary Artery Bypass Grafting with a Clampless Device versus Partial Clamping of the Ascending Aorta

: It is not known whether use of a clampless facilitating device during proximal graft anastamosis decreases intraoperative cerebral emboli in patients with mild atherosclerotic ascending aorta (AAA) having off-pump coronary artery bypass. : After intraoperative epiaortic ultrasound showed no more than mild (grade I-II) atherosclerotic ascending aorta, 20 patients were randomized to receive either partial clamping (PC, n = 10) or the HEARTSTRING clampless device (HS, n = 9) for proximal graft construction on the ascending aorta. Continuous transcranial Doppler monitoring, with capability to discern gaseous from solid particulates, was used intraoperatively to monitor high-intensity transient signals (HITS) in the middle cerebral arteries. Postoperative diffusion-weighted brain magnetic resonance imaging documented old and new ischemic brain lesions. : There were no significant differences between the groups in the number of proximals (P = 0.14), distals (P = 0.4), or intraoperative cell saver transfusions (P = 0.69). The total number of HITS was not significantly different between the PC and HS groups (P = 0.2). However, the number of solid HITS was significantly lower in the HS than in the PC group (2.7 ± 2.6 versus 14.0 ± 8.1; P < 0.001). The number of gaseous emboli in the HS group was fourfold greater when a mister-blower rather than a suction device was used to clear blood away from the HS site. Postoperatively, there were no deaths, myocardial infarctions, or clinical strokes observed in either group. Diffusion-weighted cerebral magnetic resonance imaging revealed no statistical difference between groups for new infarct lesions. : Use of the HS device during off-pump coronary artery bypass was associated with significantly fewer intraoperative solid emboli in the middle cerebral artery than PC of the ascending aorta.

CEA・CASの周術期における経頭蓋超音波検査

CEA・CASの周術期における経頭蓋超音波検査

The Safety and Efficacy of Continuous Transcranial Duplex Doppler Monitoring of Middle Cerebral Artery Occlusion in Acute Stroke Patients: Comparison of TCDD and Thrombolysis in MCA Recanalization

Assess the safety and efficacy of the continuous transcranial duplex Doppler (TCDD) monitoring of middle cerebral artery (MCA) (M1-2) occlusion in acute ischemic stroke (IS) patients and compare TCDD to intra-arterial thrombolysis (IAT) and intravenous thrombolysis (IVT). Forty consecutive acute IS patients were analyzed. Standard IVT was performed within 3 hours since stroke onset in 20 patients; between 3 and 6 hours continual 60 minute TCDD monitoring of occluded MCA using 2-MHz probe was performed in 10 patients and IAT in 10 patients. Neurological deficit was evaluated using the National Institutes of Health Stroke Scale and clinical outcome using modified Rankin Scale. The incidence of symptomatic intracerebral hemorrhage (sICH), clinical outcomes, and recanalization rates were compared among TCDD, IVT, and IAT. Analysis of variance, Kruskal-Wallis, and chi(2) tests were used for statistical evaluation. Incidence of sICH was 0% in TCDD group, 5% in IVT, and 20% in IAT (P= .198). Good 90-day clinical outcome (mRS 0-2) was achieved in 70% of TCDD patients (P= .570); recanalization after TCDD was found in 60% of patients (IVT 45%, IAT 70%) (P= .185). Continual TCDD monitoring might be safe and potentially beneficial in treatment of MCA occlusion.

Impaired Autoregulation of Cerebral Blood Flow During Rewarming from Hypothermic Cardiopulmonary Bypass and Its Potential Association with Stroke

Patient rewarming after hypothermic cardiopulmonary bypass (CPB) has been linked to brain injury after cardiac surgery. In this study, we evaluated whether cooling and then rewarming of body temperature during CPB in adult patients is associated with alterations in cerebral blood flow (CBF)-blood pressure autoregulation. One hundred twenty-seven adult patients undergoing CPB during cardiac surgery had transcranial Doppler monitoring of the right and left middle cerebral artery blood flow velocity. Eleven patients undergoing CPB who had arterial inflow maintained at >35 degrees C served as controls. The mean velocity index (Mx) was calculated as a moving, linear correlation coefficient between slow waves of middle cerebral artery blood flow velocity and mean arterial blood pressure. Intact CBF-blood pressure autoregulation is associated with an Mx that approaches 0. Impaired autoregulation results in an increasing Mx approaching 1.0. Comparisons of time-averaged Mx values were made between the following periods: before CPB (baseline), during the cooling and rewarming phases of CPB, and after CPB. The number of patients in each phase of CPB with an Mx >4.0, indicative of impaired CBF autoregulation, was determined. During cooling, Mx (left, 0.29 +/- 0.18; right, 0.28 +/- 0.18 [mean +/- SD]) was greater than that at baseline (left, 0.17 +/- 0.21; right, 0.17 +/- 0.20; P <or= 0.0001). Mx increased during the rewarming phase of CPB (left, 0.40 +/- 0.19; right, 0.39 +/- 0.19) compared with baseline (P <or= 0.001) and the cooling phase (P <or= 0.0001), indicating impaired CBF autoregulation. After CPB, Mx (left, 0.27 +/- 0.20; right, 0.28 +/- 0.21) was higher than at baseline (left, P = 0.0004; right, P = 0.0003), no different than during the cooling phase, but lower than during rewarming (left, P <or= 0.0001; right, P <or= 0.0005). Forty-three patients (34%) had an Mx >or=0.4 during the cooling phase of CPB and 68 (53%) had an average Mx >or=0.4 during rewarming. Nine of the 11 warm controls had an average Mx >or=0.4 during the entire CPB period. There were 7 strokes and 1 TIA after surgery. All strokes were in patients with Mx >or= 0.4 during rewarming (P = 0.015). The unadjusted odds ratio for any neurologic event (stroke or transient ischemic attack) for patients with Mx >or= 0.4 during rewarming was 6.57 (95% confidence interval, 0.79 to 55.0, P < 0.08). Hypothermic CPB is associated with abnormal CBF-blood pressure autoregulation that is worsened with rewarming. We found a high rate of strokes in patients with evidence of impaired CBF autoregulation. Whether a pressure-passive CBF state during rewarming is associated with risk for ischemic brain injury requires further investigation.

Optimization of flow reserve measurement using SPECT technology to evaluate the determinants of coronary microvascular dysfunction in diabetes

The aim of this study was to validate a new method to measure regional myocardial perfusion reserve (MPR) with technetium-labelled tracers in patients with type 2 diabetes mellitus (DM2). A total of 40 consecutive DM2 patients without history of coronary artery disease (CAD) and 7 control subjects were recruited. Dipyridamole myocardial blood flow index (MBF) was assessed by measuring first transit counts in the pulmonary artery and myocardial count rate from gated SPECT images using (99m)Tc-labelled tracers. The corresponding MBF index was estimated 2 h later according to the same procedure. Regional myocardial perfusion reserve (MPR) was defined as the ratio between dipyridamole and baseline MBF using a 17-segment left ventricular (LV) model. Coronary flow reserve (CFR) was estimated by transthoracic contrast echo Doppler monitoring of flow velocity in the left anterior descending coronary artery (LAD) during the same session. Estimated MPR was higher in control subjects than in patients (3.36 +/- 0.66 vs 1.91 +/- 0.61, respectively, p < 0.01). In patients, LAD CFR and LAD MPR were 2.01 +/- 0.78 vs 1.93 +/- 0.63, respectively (p = ns). The agreement between the two techniques was documented by their close correlation (r = 0.92, p < 0.001) and confirmed by the Bland-Altman analysis. Reversible perfusion defects occurred in 13 patients (32%) who showed similar MPR values as the remaining 27 (2.10 +/- 0.71 vs 1.83 +/- 0.71, respectively, p = ns). Finally, MPR was closely correlated with age (r = -0.50, p < 0.01) and time elapsed from the diagnosis of DM2 (r = -0.51, p < 0.01). LV regional MPR can be accurately estimated with the broadly available single photon technology. Application of this method to DM2 patients documents the presence of a microvascular dysfunction homogeneously distributed throughout the LV walls and most frequently not associated with reversible perfusion defects.

Atherosclerotic Plaque Composition and Cerebral Embolization after Carotid Stenting

Background: Previous studies have investigated the predictive value of clinical and morphologic parameters for distal embolization during carotid interventions. The composition of the atherosclerotic plaque using virtual histology intravascular ultrasound (VH IVUS) imaging at the intervention site has not been evaluated as a marker for cerebral embolization. The purpose of this study was to assess the relationship between atherosclerotic plaque composition determined with VH IVUS and the occurrence of cerebral embolization after carotid angioplasty and stenting (CAS). Methods: During a 10-month period, 24 patients undergoing CAS procedures using a filter device for embolic protection (Accunet Filter, Abbott Vascular, Santa Clara, Calif) were prospectively evaluated. All patients underwent VH IVUS imaging before the intervention, transcranial Doppler (TCD) monitoring during CAS, and preprocedural and 24-hour postprocedural diffusion-weighted magnetic resonance imaging (DW-MRI). VH-IVUS characterized plaque components as fibrotic, fibrofatty, dense calcium, and necrotic core. The frequency of Doppler-detected microembolic signals (MES) during CAS and the incidence and location of acute, postprocedural embolic lesions detected with DW-MRI was assessed to determine cerebral embolization. Univariate and linear regression analyses were used to assess the association between plaque composition and the frequency of cerebral embolization. Results: No periprocedural transient ischemic attacks, strokes, or deaths occurred at 30 days. DW-MRI demonstrated new acute cerebral emboli in 14 patients (58%). All revealed ipsilateral lesions, and eight (32%) had also contralateral lesions. For the entire study group, the median number of DW-MRI lesions was two (range, 0-173) and the TCD MES counts were 222 (interquartile range, 152-322) .Of the plaque components, DW-MRI determined that only dense calcium was significantly associated with cerebral embolization. The proportion of dense calcium was significantly larger in patients with cerebral embolization (5.7% ± 2.2% vs 1.2% ± 0.3%, P = .04). Findings on postprocedural DW-MRI did not correlate with the proportion of fibrotic, fibrofatty, and necrotic core. Degree of cerebral embolization during CAS measured with TCD did not correlate with plaque composition. Conclusions: Plaque composition, as determined by VH IVUS, correlates with the degree of cerebral embolization after CAS but not during the intervention. Specifically, the proportion of dense calcium is strongly associated with the occurrence of cerebral embolization after CAS. Of note, the proportion of necrotic core, which has traditionally defined the presence of a vulnerable or unstable plaque, does not correlate with the degree of distal embolization after CAS when a filter device for embolic protection is used. Optimal management and strategies to prevent distal embolization after CAS of lesions with significant dense calcium warrant further investigation.

Comparison of a supra-sternal cardiac output monitor (USCOM) with the pulmonary artery catheter

Cardiac output (CO) cannot reliably be estimated by clinical examination. We aimed to measure the agreement between CO measurements using a supra-sternal Doppler monitor (USCOM, Coffs Harbour, Australia) and the pulmonary artery catheter (PAC). The study was conducted in the intensive care unit of a tertiary teaching hospital. All patients with PAC in situ were eligible. Simultaneous CO readings were taken when clinically indicated. Investigators and clinicians were blinded to each other's results. The CO values used were the mean of three consecutive supra-sternal Doppler readings for patients with a sinus rhythm and seven for atrial fibrillation, and the mean of three thermodilution curves with acceptable form and values within 10% of each other for the PAC. Agreement was measured using both the paired t-test to calculate bias and limits of agreement and the intraclass correlation (ICC) coefficient. Ninety-four subjects were enrolled. From 89 subjects, 250 paired comparisons were obtained. USCOM monitor readings were unobtainable in five patients. Mean supra-sternal Doppler CO was 5.5 litre min(-1). Bias was -0.09 litre min(-1) and levels of agreement were +/- 2.92 litre min(-1) when compared with PAC. ICC was 0.46 (95% CI 0.36-0.56), and mean percentage difference was 19 (IQR 6-31)%. In our subjects, there was poor agreement between CO measurements done with the supra-sternal Doppler monitor and PAC.

Brain activity and presence: a preliminary study in different immersive conditions using transcranial Doppler monitoring

Transcranial Doppler (TCD) sonography is a brain activity measurement technique that monitors the hemodynamic characteristics of the major cerebral arteries in normal and pathological conditions. As it is not invasive, it can be easily used in combination with virtual environments (VE). In the present study, TCD has been used to analyze brain activity variations in different presence conditions during the exposure to a VE. Forty-two subjects have taken part in the experience grouped in two different visualization conditions: a CAVE-like and a single screen projection configuration. In each session, two different navigation conditions were used: a free navigation (controlled by the subject) and an automatic navigation (controlled by the system). Results show that these immersion and navigation modifications in the VE generate changes in brain activity that can be detected using TCD techniques. Several factors, one of them being presence, could be having an influence on this behavior.

Transcranial Measurement of Cerebral Microembolic Signals During Endocardial Pulmonary Vein Isolation: Comparison of Three Different Ablation Techniques

Isolation of the pulmonary veins (PVI) using high ablation energy is an effective treatment for atrial fibrillation (AF) with a success rate of 50-95%; however, postoperative neurological complications still occur in 0.5-10%. In this study the incidence of cerebral microembolic signals (MES) as a risk factor for neurological complications is examined during 3 percutaneous endocardial ablation procedure strategies: segmental PVI using a conventional radiofrequency (RF) ablation catheter, segmental PVI using an irrigated RF tip catheter, and circumferential PVI with a cryoballoon catheter (CB). Thirty patients underwent percutaneous endocardial PVI. Ostial isolation was performed in 10 patients with a conventional 4-mm RF catheter (CRF) and in 10 patients with a 4-mm irrigated RF catheter (IRF). A circumferential PVI was performed in 10 patients with a CB. Transcranial Doppler (TCD) monitoring was used to detect MES in the middle cerebral arteries. The total number of cerebral MES differs significantly among the 3 PVI groups; 3,908 cerebral MES were measured with use of the CRF catheter, 1,404 cerebral MES with use of the IRF catheter, and 935 cerebral MES with use of the CB catheter. This study demonstrates a significant difference in cerebral MES during PVI with 3 different ablation procedures. The use of an irrigated RF and a cryoballoon produces significantly fewer cerebral MES than the use of conventional RF for a PVI procedure, suggesting a higher risk for neurologic complications using conventional RF energy during a percutaneous PVI procedure.

56 eases of uterine leiomyoma Treatment of Clinical Analysis

Objective To observe the application of the drug mifepristone treatment the clinical effects of uterine fibroids.Methods 56 cases of uterine myoma in patients with oral mifepristone 10 mg,1 times/d,even serving 90 d for one course of treatment,the application of color Doppler monitoring before and after treatment of uterine leiomyoma Change,determination of liver and kidney function,hemoglobin observed adverse reactions after medication.Results 56 patients with medication both during amenorrhea,symptoms of anemia were improved after treatment of uterine and fibroid volume were narrowing (P＜0.05),estrogen and progesterone drop of water on average (P＜ 0.01).Medication early gastrointestinal discomfort,one week after symptoms disappear,no changes in liver and kidney functions.Conclusions The clinical effects of mifepristone treatment of uterine leiomyomas have a certain effect,is a safe,effective,economic,and treatment of minor side effects,especially suitable for grass-roots hospitals. Key words: Hysteromyoma; Mifepristone; Treatment

TCT-49: Transcranial Doppler Monitoring During Carotid Artery Stenting: Comparison between Flow Reversal and Filter for Cerebral Protection

TCT-49: Transcranial Doppler Monitoring During Carotid Artery Stenting: Comparison between Flow Reversal and Filter for Cerebral Protection

Evaluation of stroke volume variation obtained by arterial pulse contour analysis to predict fluid responsiveness intraoperatively

Fluid management guided by oesophageal Doppler monitor has been reported to improve perioperative outcome. Stroke volume variation (SVV) is considered a reliable clinical predictor of fluid responsiveness. Consequently, the aim of the present trial was to evaluate the accuracy of SVV determined by arterial pulse contour (APCO) analysis, using the FloTrac/Vigileo system, to predict fluid responsiveness as measured by the oesophageal Doppler. Patients undergoing major abdominal surgery received intraoperative fluid management guided by oesophageal Doppler monitoring. Fluid boluses of 250 ml each were administered in case of a decrease in corrected flow time (FTc) to <350 ms. Patients were connected to a monitoring device, obtaining SVV by APCO. Haemodynamic variables were recorded before and after fluid bolus application. Fluid responsiveness was defined as an increase in stroke volume index >10%. The ability of SVV to predict fluid responsiveness was assessed by calculation of the area under the receiver operating characteristic (ROC) curve. Twenty patients received 67 fluid boluses. Fifty-two of the 67 fluid boluses administered resulted in fluid responsiveness. SVV achieved an area under the ROC curve of 0.512 [confidence interval (CI) 0.32-0.70]. A cut-off point for fluid responsiveness was found for SVV > or =8.5% (sensitivity: 77%; specificity: 43%; positive predictive value: 84%; and negative predictive value: 33%). This prospective, interventional observer-blinded study demonstrates that SVV obtained by APCO, using the FloTrac/Vigileo system, is not a reliable predictor of fluid responsiveness in the setting of major abdominal surgery.

Oesophageal Doppler Ultrasound in the Assessment of Haemodynamic Status of Patients Admitted to the Medical Intensive Care Unit with Septic Shock

Haemodynamic monitoring is an essential element in the management of critically ill patients in the intensive care unit (ICU). However, there have been increasing concerns about the clinical utility and safety profile of the invasive pulmonary artery catheter (PAC). Oesophageal Doppler (ED) monitoring has emerged recently as a safer and less invasive tool which can be used by the intensivist to estimate cardiac output in the critically ill patient. Validation studies have thus far only been performed in surgical patients perioperatively and in mixed surgical/medical ICU patients. Currently, minimal data are available in any sizeable Asian population or in patients with severe sepsis. The assumption that these normograms and data hold true for our local medical ICU patients may not be valid due to differences in body habitus. Our primary aim is to validate the oesophageal Doppler as a reliable measure of cardiac index, systemic vascular resistance (SVR) and preload in our local Asian population of patients with severe sepsis and septic shock in the medical ICU. This was a prospective pilot study on 12 consecutive mechanically ventilated patients in our medical ICU with the diagnosis of septic shock as defined by SCCM/ESICM/ACCP/ATS/SIS International Sepsis definitions Conference-Critical Care Medicine 2003 and required PAC haemodynamic monitoring as indicated by Medical Intensive Care Unit attending. Ninety-seven paired cardiac output measurements were made. Cardiac output ranged from 2.87 to 11.0 L/ min (calculated cardiac index ranging from 1.73 to 6.36 L/min/m2) when measured using the PAC with thermodilution technique and from 2.0 to 12.1 L/min (calculated cardiac index of 1.2 to 7.2 L/min/m2) using the trans-oesophageal Doppler. There was moderately good correlation between CIpac and CIed (correlation coefficient, r = 0.762 with PCA = 58%). The mean bias was 0.26 L/min/m2 (P <0.07), while the limit of agreement was +/- 1.44 L/min/m2. ED has good correlation with PAC in measuring cardiac index in Asians with septic shock but is an unreliable measure of both pre-load and SVR.