Anesthetic Management in Tracheal Dilatation for Severe Tracheal Stenosis.

We report the anesthetic management of a 65-year-old woman with recurrent, severe tracheal stenosis who underwent tracheal dilatation. She had visited the Department of Respiratory Medicine at our hospital for respiratory distress approximately 20 years ago, and had undergone laser ablation under local anesthesia. Because of recurrence and aggravation of respiratory distress, she now presented at the Department of Thoracic Surgery, and was scheduled for surgery. Percutaneous cardiopulmonary support was prepared, and she was sedated with midazolam and dexmedetomidine. Under bronchoscopic guidance, a 5-mm intubation tube was placed directly above the stenosis site. Laser ablation (by argon plasma coagulation) and balloon dilatation were performed, and the tube was replaced with one with a larger diameter, which was subsequently replaced with another with an even larger diameter. Ultimately, a 7-mm tube was placed beyond the stenosis site, and the operation was completed. After restoration of spontaneous respiration and consciousness, the patient was extubated in the operating room and returned to the intensive care unit. In anesthetic management of patients with tracheal stenosis, treatment of hypoxia is important. In this case, we collaborated with the attending physician, clinical engineers, and operating room nurses throughout, and consequently, were able to perform the operation safely.

Insulin adsorption into porous charged membranes: effect of the electrostatic interaction.

Insulin adsorption into a series of porous charged membranes was investigated by batch adsorption experiments, and the experimental results were analyzed by the homogeneous diffusion model. The membranes used in this study were prepared by pore-surface modification of porous poly(acrylonitrile) (PAN) membranes by grafting with weak acidic and basic functional groups. The amount of insulin adsorbed into the membrane was determined from the material balance of insulin. The insulin partition coefficient K between the membrane and solution was estimated from the equilibrium adsorption amount, and the effective diffusion coefficient D was estimated by matching the model with the experimental data as a fitting parameter. The dependence of K and D on the charge properties of the insulin and membrane is observed and discussed. The partition coefficient K increased when the insulin and the membrane carried opposite charges, on the other hand, the effective diffusion coefficient D was reduced. These results indicate that the electrostatic interaction between the insulin and the membranes played an important role in the insulin adsorption.

Insulin transport across porous charged membranes: Effect of the electrostatic interaction.

Insulin transport phenomena across a series of porous charged membranes were studied at two pH conditions (pH 3.3 and pH 7.4) in this article. The membranes were prepared by pore-surface modification of porous poly(acrylonitrile) (PAN) membranes by grafting with weak acidic and basic functional groups. The insulin partition coefficient K between the membrane and solution was estimated from the equilibrium adsorption amount in the batch adsorption experiment. The insulin effective diffusion coefficient D inside the membrane was determined as a fitting parameter by matching the diffusion model with the experimental data of the diffusion measurement. Both K and D correlated well with the charge properties of the insulin and membrane: when the insulin and membrane carried opposite net charge, the partition coefficient showed relatively larger values, while the effective diffusion coefficient was reduced. The insulin permeability coefficient P obtained from the experimental results agreed with that estimated from the partition coefficient and effective diffusion coefficient. These results suggested that the combined effects of the solubility and diffusivity on the permeability coefficient complicated the relationship between the permeability and the charge properties of the insulin and membrane. Additionally, our calculation supported that insulin permeability was reduced by the boundary layer between the membrane and solution.