Chiyo Ootaki

Ultrasound-guided infraclavicular brachial plexus block: An alternative technique to anatomical landmark-guided approaches

Background and Objectives Infraclavicular brachial plexus block has been used less than other approaches because of its less uniform landmarks and the necessity of a longer needle, which increases the patient’s discomfort. To overcome these drawbacks, we applied ultrasound guidance to infraclavicular approach and prospectively evaluated its feasibility and usefulness in 60 patients undergoing upper extremity surgery. Methods A 7.0-MHz ultrasound probe was placed near the lower edge of the clavicle, and a transverse view of the subclavian artery and vein was visualized. Using a needle guide, a 23-gauge needle was advanced under real-time ultrasound guidance, and 1.5% lidocaine with 1:200,000 epinephrine was injected near the subclavian artery, 15 mm medially and 15 mm laterally to the artery. The extent of sensory and motor block was evaluated at 30 minutes after the injection. Results An adequate ultrasound image was obtained for all the patients. In 57 patients (95%), surgery was performed without supplementation of any other anesthetics or analgesics. The complete sensory block was obtained in 100% of patients for the musculocutaneous and medial antebrachial cutaneous nerves, 96.7% for the median nerve, and 95% for the ulnar and radial nerves. The complete motor block was achieved in 100% of patients for the musculocutaneous nerve, 96.7% for the median nerve, 90% for the ulnar nerve, and 93.3% for the radial nerve. No evidence of any complications was identified. Conclusions Real-time ultrasound guidance facilitates accurate infraclavicular approach to the brachial plexus. It could be used as an alternative to the landmark-guided techniques.

Reduced Pulsatility Induces Periarteritis in Kidney: Role of the Local Renin-Angiotensin System

OBJECTIVE The need for pulsatility in the circulation during long-term mechanical support has been a subject of debate. We compared histologic changes in calf renal arteries subjected to various degrees of pulsatile circulation in vivo. We addressed the hypothesis that the local renin-angiotensin system may be implicated in these histologic changes. METHODS AND RESULTS Sixteen calves were implanted with devices giving differing degrees of pulsatile circulation: 6 had a continuous flow left ventricular assist device (LVAD); 6 had a continuous flow right ventricular assist device (RVAD); and 4 had a pulsatile total artificial heart (TAH). Six other calves were histologic and immunohistochemical controls. In the LVAD group, the pulsatility index was significantly lower (0.28 +/- 0.07 LVAD vs 0.56 +/- 0.08 RVAD, vs 0.53 +/- 0.10 TAH; P < 0.01), and we observed severe periarteritis in all cases in the LVAD group. The number of angiotensin II type 1 receptor-positive cells and angiotensin converting enzyme-positive cells in periarterial areas was significantly higher in the LVAD group (angiotensin II type 1 receptor: 350 +/- 139 LVAD vs 8 +/- 6 RVAD, vs 3 +/- 2 TAH, vs 3 +/- 2 control; P < .001; angiotensin-converting enzyme: 325 +/- 59 LVAD vs 6 +/- 4 RVAD, vs 6 +/- 5 TAH, vs 3 +/- 1 control; P < .001). CONCLUSIONS The reduced pulsatility produced by a continuous flow LVAD implantation induced severe periarteritis in the kidneys. The local renin-angiotensin system was up-regulated in the inflammatory cells only in the continuous flow LVAD group.

A novel device for left atrial appendage exclusion: The third-generation atrial exclusion device

OBJECTIVE Occlusion of the left atrial appendage is proposed to reduce the risk of stroke in patients with atrial fibrillation. The third-generation atrial exclusion device, modified to provide uniform distribution of pressure at appendage exclusion, was assessed for safety and effectiveness in a canine model and compared with a surgical stapler. METHODS The atrial exclusion device consists of 2 parallel, straight, rigid titanium tubes and 2 nitinol springs with a knit-braided polyester fabric. Fourteen mongrel dogs were implanted with the device at the base of the left atrial appendage via a median sternotomy. In each dog, the right atrial appendage was stapled with a commercial apparatus for comparison. The animals were evaluated at 7 days (n = 3), 30 days (n = 5), and 90 days (n = 6) after implantation by epicardial echocardiography, left atrial and coronary angiography, gross pathology, and histology. RESULTS Left atrial appendage exclusion was complete and achieved without hemodynamic instability, and coronary angiography revealed that the left circumflex artery was patent in all cases. A new endothelial tissue layer developed on the occluded orifice of the left atrium 90 days after implantation. This endothelial layer was not evident on the stapled right atrial appendage. CONCLUSION In dogs, the third-generation atrial exclusion device achieved easy, reliable, and safe exclusion of the left atrial appendage with favorable histologic results. Clinical application could provide a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation.

Acute in vivo evaluation of an implantable continuous flow biventricular assist system.

An implantable biventricular assist device offers a considerable opportunity to save the lives of patients with combined irreversible right and left ventricular failure. The purpose of this study was to evaluate the hemodynamic and physiologic performance of the combined implantation of the CorAide™ left ventricular assist device (LVAD) and the DexAide right ventricular assist device (RVAD). Acute hemodynamic responses were evaluated after simulating seven different physiological conditions in two calves. Evaluation was performed by fixing the speed of one individual pump and increasing the speed of the other. Under all conditions, increased LVAD or RVAD speed resulted in increased pump flow. The predominant pathophysiologic effect of independently varying DexAide and CorAide pump speeds was that the left atrial pressure was very sensitive to increasing RVAD speed above 2,400 rpm, whereas the right atrial pressure demonstrated much less sensitivity to increasing LVAD speed. An increase in aortic pressure and RVAD flow was observed while increasing LVAD speed, especially under low contractility, ventricular fibrillation, high pulmonary artery pressure, and low circulatory blood volume conditions. In conclusion, a proper RVAD-LVAD balance should be maintained by avoiding RVAD overdrive. Additional studies will further investigate the performance of these pumps in chronic animal models.

Development of the DexAide right ventricular assist device inflow cannula.

Cannula design and cannulation site can pose major limitations to chronic pump implantations in animal studies. The aim of this study was to evaluate the biocompatibility of various inflow cannula designs for the DexAide right ventricular assist device (RVAD). The DexAide RVAD was implanted for intended durations of 14, 30, or 90 days in 19 animals (mean 20 ± 11 days). Seven inflow cannula designs were evaluated: angled titanium conduit with caged tip (two cases); flexible polyurethane coated polyvinyl chloride (PVC) tube (one case); open ended titanium (one case); a titanium cannula with a flange (six cases); a cannula with a gelatin coated flange (five cases); a cannula with an angled flange (one case); and open ended titanium with two side holes (three cases). The open ended titanium inflow cannula with two side holes positioned through the diaphragmatic surface of the right ventricle (RV) via a right thoracotomy showed good biocompatibility for the chronic animal study. Other cannulae inserted into the infundibular portion of the RV via a left thoracotomy showed significant depositions. Gelatin coated inflow cannula had the advantage to prevent tissue growth around the inflow cannula. The DexAide RVAD pump itself showed good biocompatibility, although nonadherent depositions originating from the inflow cannulae were captured onto the primary impeller blades.

Does general anesthesia increase the diagnostic yield of endoscopic ultrasound-guided fine needle aspiration of pancreatic masses?

Background:Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) of the pancreas has become the preferred method for tissue diagnosis for pancreatic solid masses. The yield of EUS-FNA in this setting is influenced by multiple factors. We hypothesized that general anesthesia (GA) may improve EUS-FNA yield by improving patient cooperation and stillness during the procedure. Our objective was to assess the association between the sedation method employed and the diagnostic yield of EUS-FNA. Methods:A retrospective cohort study was conducted involving consecutive patients who received EUS-FNA for diagnosis of a solid pancreatic mass at the Cleveland Clinic (Cleveland, OH) gastrointestinal endoscopy units from 2007 to 2009. We compared the diagnostic yield of EUS-FNA between patients receiving GA provided by an anesthesiologist (GA group) and patients receiving conscious sedation (CS) provided by a qualified registered nurse (CS group). Results:Of 371 patients, a cytological diagnosis was obtained in 73/88 patients (83%) in the GA group and 206/283 patients (73%) in the CS group. Anesthesiologist-delivered GA was associated with an increased odds of having a successful diagnosis as compared with CS (adjusted odds ratio [95% CI]: 2.56 [1.27–5.17], P = 0.01). However, the incidence of complication during or after the procedure was not different between the groups (P > 0.99). Conclusions:Anesthesiologist-delivered GA was associated with a significantly higher diagnostic yield of EUS-FNA. GA should be considered a preferred sedation method for EUS-FNA of a solid pancreatic mass.

Comparative study of heart rate variability between healthy human subjects and healthy dogs, rabbits and calves

Several studies have been performed to assess heart rate variability (HRV) in several species such as humans, dogs, pigs, calves, rabbits and rats. However, haemodynamic parameters are totally different in each animal, and optimal animal models for studying HRV corresponding to human HRV are still unclear. The purpose of this study was to assess HRV in human subjects and to compare those HRV data with canine, bovine and rabbit HRV data. The heart rate in the human subjects (62.8 ± 7.4 bpm) was significantly lower than that in dogs (124.2 ± 18.8 bpm, P < 0.001), calves (73.4 ± 10.5 bpm, P < 0.05), and rabbits (217.3 ± 21.5 bpm, P < 0.001). The low-frequency waves (LF) (57.9 ± 65.8 ms2/Hz) and high-frequency waves (HF) (33.8 ± 49.1 ms2/Hz) in rabbits were significantly lower than human LF (1216.3 ± 1220.7 ms2/Hz, P < 0.05) and HF (570.9 ± 581.3 ms2/Hz, P < 0.05). Dogs and calves showed similar LF (991.1 ± 646.1 ms2/Hz and 547.0 ± 256.9 ms2/Hz, respectively), HF (702.1 ± 394.1 ms2/Hz and 601.0 ± 666.6 ms2/Hz, respectively) and LF/HF (2.0 ± 1.3 and 2.5 ± 1.9, respectively) when compared with the human data. The present study shows that dogs and calves revealed similar HRV values as those which relate to humans. Large deviation of the HRV values in rabbits compared with humans might be considered when conducting animal studies using those animals to reflect human clinical situations.

Beating Heart Cardioscopy: A Platform for Real-Time, Intracardiac Imaging

PURPOSE The purpose of this study was to develop a method for real-time, fiberoptic, intracardiac imaging to serve as a platform for closed-chest, intracardiac surgery on the beating heart. DESCRIPTION Fiberoptic cardioscopy of the left and right heart was conducted in a porcine model. A cardiopulmonary bypass circuit maintained systemic organ perfusion and a separate circuit replaced intracardiac blood with oxygenated, modified Krebs-Henseleit perfusate. EVALUATION Video images of structures in the left and right sides of an in vivo beating heart were obtained, including the inner surface of the left and right atria and ventricles, the mitral and aortic valves, the Thebesian veins, and the coronary sinus. Effective isolation of the heart from systemic and intracardiac blood flow and control of perfusion rates were important factors for successful image acquisition. CONCLUSIONS Fiberoptic cardioscopy is a novel approach that allows for visualization of the structures within a nonarrested heart on bypass. It lays the groundwork for a platform that could lead to more successful percutaneous valvular and intracardiac procedures in a stable hemodynamic environment.

Progress in the development of the DexAide right ventricular assist device.

The DexAide right ventricular assist device (RVAD) is an implantable centrifugal pump modified from the CorAide left ventricular assist device. As previously published, in vitro performance testing of the DexAide RVAD has met design criteria, and the nominal operating condition of 4 l/min and 20 mm Hg pressure rise was achieved at 2,000 rpm, with a power consumption of 1.9 watts. In vivo studies in 14 calves have demonstrated acceptable hemodynamic characteristics. The calf inflow cannula design is still evolving to minimize depositions on the cannula observed in most experiments. Fitting studies were performed in 5 cadavers and 2 patients to reconfigure the cannulae for use in humans. The design and development of external electronics have been completed for the stand-alone RVAD system, and verification tests are under way in preparation for preclinical tests. Work on the external electronics design for the biventricular assist system is ongoing. In conclusion, the initial in vitro and in vivo studies have demonstrated acceptable hemodynamic characteristics of the DexAide RVAD. The design and development of the external electronic components for the stand-alone RVAD system have been completed. The calf inflow cannula is being redesigned, and chronic in vivo tests are under way.

Respiratory jugular venodilation: A new landmark for right internal jugular vein puncture in ventilated patients☆

OBJECTIVE To report a new technique for right internal jugular vein puncture using respiratory jugular venodilation as a landmark for vein location. DESIGN Prospective observational study. SETTING Single community hospital. PARTICIPANTS Two hundred patients undergoing right internal jugular vein cannulation under general anesthesia. INTERVENTIONS Catheter placement was attempted using respiratory jugular venodilation as the primary landmark. When it was not applicable, an alternative technique using the carotid pulse as a landmark was used. MEASUREMENTS AND MAIN RESULTS Visibility of the venodilation, the number of needle passes, the success rate, and the incidence of arterial puncture were analyzed. Respiratory jugular venodilation was observed in 158 patients (79%). In this group of patients, the jugular vein was cannulated at the first attempt in 83.5% of patients, and arterial puncture occurred in one patient (0.6%). In the remaining 42 patients (21%) lacking the visible venodilation, catheter placement was accomplished at the first attempt in 42.9% of patients (p<0.01 v. the venodilation-visible group), and 4 patients (9.5%) suffered arterial puncture (p<0.01). The overall incidence of arterial puncture was 2.5%. The success rate of cannulation (within four needle passes and no arterial puncture) was 98.1% in the venodilation-visible patients and 73.8% in the others (p<0.01), with the overall success rate of 93%. CONCLUSIONS Respiratory jugular venodilation can be identified in a large proportion of ventilated patients. This experience suggests that respiratory jugular venodilation could be favorably used as the primary landmark for right internal jugular vein puncture in anesthetized patients.