Biomaterials have been contributing to clinical medicine as artificial organs, disposable medical devices, and materials for surgical operations, but many problems remain to be solved in regard to the biomaterials currently being used. There are a number of biomaterials that have not yet been applied to medicine although strongly requested by physicians. This review article first describes the minimum requirements for biomaterials, which include biosafety, sterilizability, and biocompatibility. Differences in biocompatibility from the standpoint of biosafety, and the importance of the biocompatibility are stressed. A more detailed overview is provided in regard to currently used artificial tissues and organs, focusing on present problems and future expectations. Approximately 20 artificial tissues and organs are selected. Finally, this article predicts that two major directions of biomaterials research will be medical applications of absorbable biomaterials and tissue engineering. It is pointed out that absorbable materials of higher mechanical strength are needed to promote their surgical applications. The emerging biomaterial field is expected to be tissue engineering that regenerates biological tissues or reconstructs biological organs by using autogeneic, allogeneic, or xenogeneic cells together with biomaterials.

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To investigate cerebral carbon dioxide (CO₂) reactivity in head injured patients, continuous jugular venous oxygen saturation (SjO₂) monitoring with a fiberoptic catheter (Opticath) was performed, and the validity of this method was also evaluated. Thirty-two patients with severe head injuries underwent continuous monitoring of SjO₂ in the intensive care unit. Within 24 hours after head injury, CO₂ reactivity was measured using ventilatory manipulation, and subsequent changes in SjO₂ values were determined. The formula derived from Fick's principle was used to calculate the CO₂ reactivity values. No catheter related complications were observed. In 12 patients, data showed a significant correlation between SjO₂ values obtained by the catheter monitoring system and those measured by Co-oximeter (r²=0.932, p<0.0001). During ventilatory manipulation, changes in SjO₂ were 5.8±3.4% and 8.3±2.7mmHg for arterial CO₂ tension (PaCO₂). CO₂ reactivity was calculated at 1.75±1.16/mmHg of PaCO₂. There was a significant correlation between patient outcome and CO₂ reactivity value. Patients with favorable outcomes (p<0.0001) and with poor outcomes (p<0.0001) had higher reactivity values than those of deceased patients. Also a significant correlation was found between type of intracranial lesion and CO₂ reactivity. Patients with diffuse lesions (p<0.05) had higher reactivity values than those with evacuated mass lesions. Furthermore, CO₂ reactivity measured with SjO₂ values on the monitor presented valid data in the clinical setting. The monitor provided clinical and prognostic information for the management of severe head injury without any significant difficulties.

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The purpose of this study was to assess the diagnostic accuracy of biplane transesophageal echocardiography (TEE) in locating intimal fenestration and side branch involvement in aortic dissection. Sixty-nine patients (39 men and 30 women) aged 41-81 years with proven aortic dissection, who were reffered for surgical therapy, were examined by TEE during the acute phase. The defect's entry site was indentified either as a high velocity color Doppler flow issueing from a false lumen into a true lumen or estimated by the aortic portion where the false lumen flow originated. We attempted to visualize the aortic valves, the coronary areteries and the aortic arch vessels and to examine side branch involvement. Intraoperative inspection of the aorta was performed. The sensitivity of TEE was calculated from the percent of validated true positives. The sensitivities of TEE for an entry site and involvements of aortic valves, coronary arteries and aortic arch vessels were 90%, 85%, 83% and 63%, respectively. TEE is an excellent method for evaluating entry site and side branch involvement except for parts of the aortic arch vessels when acute aortic dissection has occurred.

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The outcomes of 48 patients with hypertensive intracerebellar hemorrhage were investigated. Our series included 13 male and 35 female patients, ranging in age from 44 to 84 years with a mean age of 64.4 years. Of the 48 patients, 22 were treated conservatively and 26 underwent operation: ventricular drainage in 3, suboccipital craniotomy in 10 and stereotactic aspiration surgery (AS) in 13. Kanaya's neurological grade (Grade) on admission was Grade 1 in 10, Grade 2 in 12, Grade 3 in 9, Grade 4a in 5, and Grade 4b or 5 in 12 patients. Conservative treatment was performed in 18 patients at Grades 1 to 4a, of which 17 at Grades 1 to 3 showed good recovery to moderate disability. Fifteen of these 17 patients at Grades 1 or 2 had small hematomas under 10ml. All patients at Grades 4b or 5 showed severe disability, vegetative state or death in outcomes, regardless of the type of treatment. At Grades 1 to 4a, surgical treatment was performed in 18 patients: ventricular drainage in 2, evacuation via suboccipital craniotomy in 4, and AS combined with ventricular drainage in 12 cases. AS was performed by suboccipital trephination using Komai's CT-stereotactic apparatus. AS in the subacute stage was performed in 7 patients atf Grades 1, 2 and 3. The average evacuation rate was 78%, and the symptoms were improved in all patients and resulted in good recovery to moderate disability. In the acute stage, AS was performed within 48 hours of onset in 5 patients at Grades 2 and 3 with aggravating symptoms and at Grade 4a without aggravating symptoms. The average evacuation rate of hematoma was 68% and the symptoms were improved in all patients, and resulted in moderate disability outcomes. To decrease mortality in the acute stage, AS should be appropriately timed to control acute intracranial hypertension by combined ventricular drainage. We conclude that AS for patients at Grade 2 to 4a can provide a good prognoses not only in the subacute, but also in the acute stage of hypertensive intracerebellar hemorrhage.

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The patient was a 31-year-old woman, who was diagnosed as having systemic lupus erythematosus and administered 10mg/day of prednisolone. She was in pregnancy at 38 weeks. She was referred to the department of surgery because of the development of severe abdominal pain with muscle guarding and rebound tenderness. Ultrasonography revealed marked thickening of intestinal walls and a small amount of ascites. An exploratory laparotomy and caesarian section were performed. The operative findings revealed nonbacterial peritonitis with serous ascites and segmental edema of the small bowel, compatible with lupus peritonitis. According to review of the literature, pregnancy might be unlikely to a risk factor for lupus peritonitis. Surgeons should be aware of this condition and determine whether or not the symptoms require surgery without delay, so that both mother and child might not be catastrophic.

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Patients with Bartter's syndrome, which is characterized by hypokalemia, metabolic alkalosis and hyperaldosteronism, rarely develop respiratory disturbances. We report the case of a 37-years-old woman with Bartter's syndrome, who developed respiratory failure due to muscle paralysis, and who required artificial ventilation by tracheal intubation. Although her conscious level cleared at 6 hours after admission, her voluntary ventilation was not recovered due to severe hypokalemia. Several factors such as cessation of oral potassium intake because of persistent unconsciousness induced by administration of a minor tranquilizer, Triazolam, and accidental hypothermia contributed to the hypokalemia. Insulin administration for hyperglycemia might be related to persistent hypokalemia. To normalize the potassium level and to ameliorate the respiratory condition, potassium supplementation, potassium saving diuretics and indometacin administration to inhibit prostaglandin synthesis in the kidneys may be utilized. Clinically it is important to know that a patient with Bartter's syndrome can develop severe hypokalemia and respiratory disturbances, if certain factors of hypokalemia overlap management of Bartter's syndrome.

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