Akinori Takeuchi

Effect of mild hypothermia on the expression of aquaporin family in cultured rat astrocytes under hypoxic condition

Aquaporins (AQPs) are a family of water-selective transporting proteins with homology to the major intrinsic protein (MIP) of lens, that increase plasma membrane water permeability in secretory and absorptive cells. In this study, we investigated the effect of mild hypothermia on the expression of AQP4, AQP5 and AQP9 in rat astrocytes cultured under hypoxic conditions. At 37 degrees C, a marked decrease in the expression of AQP4, AQP5 and AQP9 mRNAs was observed. However, at 32 degrees C (mild hypothermia), the expression of AQP5 mRNA was restored to its basal level. Interestingly, under mild hypothermia AQP4 mRNA expression transiently decreased and then increased about two-fold; while AQP9 mRNA expression decreased the same as at 37 degrees C. The changes in the expression of AQP4 and AQP9 proteins were confirmed by Western blot analysis. The restoration of the AQP4 and AQP5 expression at 32 degrees C from the hypoxia-induced decrease at 37 degrees C may play an important role in the reduction of brain edema under hypothermic conditions.

Skin-traction method prevents the collapse of the internal jugular vein caused by an ultrasound probe in real-time ultrasound-assisted guidance

PurposeReal-time ultrasound-assisted guidance for catheterization of the internal jugular vein (IJV) is known to be useful, especially for a small-sized vein, which is difficult to catheterize. However, one of the problems with real-time ultrasound-assisted guidance is that the ultrasound probe itself can collapse the vein. We have developed a novel “skintraction method (STM)”, in which the puncture point of the skin over the IJV is stretched upwards with several pieces of surgical tape in the cephalad and caudal directions with the aim being to facilitate catheterization of the IJV. We examined whether this method increased the compressive force required to collapse the IJV.MethodsIn ten volunteers, the compressive force required to collapse the right IJV, and the cross-sectional area and anteroposterior and transverse diameters of the IJV were measured with ultrasound imaging in the supine position (SP) with or without the STM or in the Trendelenburg position of 10° head-down (TP) without the STM.ResultsThe compressive force to required to collapse the vein was increased significantly with the STM, while the crosssectional area and anteroposterior diameter of the vein in the SP with STM were similar to those in the TP without the STM.ConclusionWith the STM, not only the cross-sectional area but also the compressive force required to collapse the IJV increased. Thus, the STM may facilitate real-time ultrasoundassisted guidance for catheterization of the IJV by maintaining the cross-sectional area of the vein during the guidance.

Inadvertent intrathecal cannulation in an infant, demonstrated by three-dimensional computed tomography: a rare complication of internal jugular vein catheterization.

We describe a case of inadvertent intrathecal cannulation with a central venous catheter in an infant, confirmed by three-dimensional computed tomography, which clearly demonstrated the track of the catheter. We believe that this complication could have been related to two major factors: depth of needle insertion and penetration of the vein by a straight-tip guidewire. To avoid this complication, the depth of needle insertion must be carefully checked, a “J”-tipped rather than a straight-tipped guidewire should be used, and puncture should be guided by ultrasound.

Postextubation airway management with nasal continuous positive airway pressure in a child with Down syndrome

We describe our experience with use of variable-flow nasal continuous positive airway pressure (NCPAP) to manage postextubation stridor in a 31-month-old child with Down syndrome (DS). Although it has been recognized that children with DS tend to develop obstruction of the upper airway postoperatively, little is known concerning appropriate management of this situation. Although there are surprisingly few reports of use of variable-flow NCPAP for children older than preterm infants, we successfully treated postextubation ventilatory complications by providing variable-flow NCPAP without complications such as pneumothorax.

Cardiac output increases the rate of carbon monoxide elimination in hyperpneic but not normally ventilated dogs.

PurposeThe very high solubility of carbon monoxide (CO) in blood suggests that its elimination depends predominantly on ventilation and not perfusion. Nevertheless, hyperventilation is not used for CO elimination because of the adverse effects of hypocapnia. With isocapnic hyperpnea (IH), ventilation can be increased considerably without hypocapnia. This raises the issue of whether CO elimination is limited by perfusion during IH. We studied the effect of increasing cardiac output on t1/2, the half-time of decline of blood carboxyhemoglobin concentration ([COHb]), during normal ventilation (NV) and during IH.MethodsAfter ethics approval was received, 13 pentobarbital-anesthetized ventilated dogs were exposed to CO to increase their [COHb]. They were then ventilated with NV or IH. At each level of ventilation, dogs were randomly assigned to treatment with dobutamine (to increase cardiac output) or to no dobutamine treatment. After the return of [COHb] to control levels, each dog was re-exposed to CO and treated with the same ventilatory mode, but the alternative inotropic treatment.ResultsGas exchange, [COHb], and hemodynamic measures were recorded during the study. Cardiac index values in the IH group were 4.1 ± 0.5 and 8.2 ± 1.2 l·min−1·m−2 without and with dobutamine infusion, respectively. Dobutamine infusion was associated with a reduction in t1/2 from 20.3 ± 3.6 to 16.9 ± 2.4 min (P = 0.005) in the IH group, but no change in the NV group.ConclusionThese findings suggest that CO elimination during IH treatment is limited at least partly by pulmonary blood flow and may therefore be further augmented by increasing cardiac output.

Before-after study of a restricted fluid infusion strategy for management of donor hepatectomy for living-donor liver transplantation

PurposeIntraoperative fluid infusion strategy remains controversial. Many animal model studies have shown that restricted fluid infusion reduces blood loss, though reports on this topic in humans are rare. The purpose of this study was to determine the effects on volume of blood loss of a restricted fluid infusion strategy for hepatectomy in donors for livingdonor liver transplantation.MethodsA before-after study design was used with prospective consecutive data collection. A total of 22 patients who underwent living-donor hepatectomy were enrolled. Eleven patients who were managed before the implementation of restricted-volume fluid administration comprised the standard-volume group, and 11 who were evaluated after the implementation of the restricted-volume infusion strategy comprised the restricted-volume group. In the standard-volume group, the donors were given 10 ml·kg−1·h−1 of lactated Ringer’s solution and additional plasma expander corresponding to blood loss. In the restricted-volume group, the donors received 5 ml·kg−1·h−1 of lactated Ringer’s solution until the resection of the hepatic graft, followed by 15 ml·kg−1·h−1 of lactated Ringer’s solution after the completion of resection until the end of the operation.ResultsIntraoperative blood loss was less in the restricted-volume group (445 ± 193 ml) than in the standard-volume group (1331 ± 602 ml; P < 0.01). Intraoperative fluid infusion was also less in the restricted-volume group (4130 ± 563 ml) than in the standard-volume group (5634 ± 1260 ml; P < 0.01). There were no differences in length of hospital stay or side effects between the two groups.ConclusionOur restricted-volume strategy reduced blood loss and had no adverse effects during living-donor hepatectomy.

A simple, lightweight CPAP-delivery device, composed of a three-way stopcock, for the nondependent lung

AbstractPurposeWe aimed to introduce a simple, lightweight continuous positive airway pressure (CPAP)-delivery device for the nondependent lung during one-lung ventilation, to investigate how the type of three-way stopcocks, and the compliance and resistance of a test lung affect the relationship between the oxygen flow rate and CPAP level produced, and to examine how the device works in a clinical setting.MethodsIn the test lung study, the bronchial blocker of a Univent tube was connected to a test lung. The effects of oxygen-flow rate, types of three-way stopcocks, and compliance and resistance of the test lung on the CPAP levels were studied. In the clinical study, the lightweight device was used to treat hypoxia in seven patients during one-lung ventilation with the bronchial blocker.ResultsIn the test lung study, the CPAP level produced by the device was proportional to the oxygen-flow rate, dependent on the type of three-way stopcock used, and independent of the compliance or resistance of the test lung. There was no discrepancy between the plateau pressures of the test lung and the monitoring port of an additional stopcock at any degree of compliance or resistance of the test lung at any oxygen-flow rate. Therefore, the relationship between the oxygen-flow rate and CPAP level can be ensured in advance before application to the lung, with an additional three-way stopcock of which the distal end is occluded. In the clinical study, peripheral oxygen sataration

A simple "new" method to accelerate clearance of carbon monoxide.

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