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Biomedical subjects

I Koga

Publications and source records attributed to I Koga.

At least 19 recordsLinked to original sources
PubMed2002

Sigmoid colonic reflectance pulse oximetry and tonometry in a porcine experimental hypoperfusion shock model.

BACKGROUND: The objective of the present study was to determine if colonic endoluminal mucosal oxygen saturation, as determined by reflectance pulse oximetry, is an appropriate method to monitor colonic ischemia produced by a gradual partial constriction of the aorta in a porcine experimental model. METHODS: Piglets were anesthetized and mechanically ventilated. A Nellcor RS-10 reflectance pulse oximeter probe was attached to a Foley balloon catheter and passed transanally to record the oxygen saturation of the sigmoid colonic mucosa. For comparison, a tonometry catheter was introduced into the sigmoid colon. Hypoperfusion shock was induced by partial gradual constriction of the aorta. The same measurements but no intervention was performed in the control group. RESULTS: During one-third reduction of the aortic blood flow, the plethysmographic signal disappeared suddenly and the sigmoid colonic mucosa oxygen saturation (ScO2) measurements showed zero in seven out of the eight pigs. During two-thirds flow reduction, no plethysmographic signals were observed in any of the piglets. During the reperfusion period, ScO2 measurements with a good plethysmographic signal were obtained immediately after complete release of the aortic constriction in all pigs. Significantly decreased intramucosal pH and increased difference between the arterial and regional PCO2 (PCO2 gap) were observed during two-thirds blood flow reduction. CONCLUSION: In contrast to the results of previous investigations, the sigmoid colonic pulse oximetry was not useful because the method proved to be overly sensitive and non-linear in relation to regional blood flow.

Animals↗
PubMed2000

Influence of segmental spinal cord perfusion on intrathecal oxygen tension during experimental thoracic aortic crossclamping.

PURPOSE: The purpose of this study was to evaluate the possibility of identifying alterations in blood supply to the spinal cord during thoracic aortic crossclamping. METHODS: In 17 pigs, a multiparameter PO(2), PCO(2,) and pH sensor was introduced into the intrathecal space for continuous monitoring of cerebrospinal fluid (CSF) oxygenation during aortic crossclamping. An epidural laser Doppler probe was used to measure spinal cord flux. After insertion of an aortic shunt from the left subclavian to the left iliac artery and interruption of the right subclavian and lumbar arteries (L2-L5), the thoracic aorta just distal to the left subclavian artery was clamped for 60 minutes. By placement of the distal aortic crossclamping below the level of L1 in group A (n = 9 animals), perfusion of only the abdominal visceral arteries was maintained. In group B (n = 8 animals), the distal aortic crossclamping was above the level of T12, and thus some spinal cord perfusion was maintained through the aortic shunt. RESULTS: The significant decrease in CSF PO(2) was observed within 3 minutes after the placement of the proximal aortic crossclamping and was normalized in all animals after establishment of the shunt flow. In group A, distal aortic crossclamping caused a decrease in CSF PO(2) with at least 50% of the preclamping values within 3 minutes. The mean CSF PO(2) of 2.99 +/- 0.70 kPa at 60 minutes of distal aortic crossclamping in group B was significantly higher than in group A (0.11 +/- 0.11 kPa; P <. 001). In group A, PCO(2) measurements showed no significant changes in 3 minutes after distal aortic crossclamping but revealed significantly higher values at 30 and 60 minutes compared with group B. Spinal cord flux values showed similar changes as CSF PO(2) during the whole experiment in both groups. CONCLUSION: In this experimental model of aortic crossclamping, continuous CSF oxygen tension monitoring allows rapid detection of alterations in spinal cord circulation.

Animals↗
PubMed2000

Intraperitoneal tonometry for detection of regional enteric ischaemia.

BACKGROUND: The objective of this study was to test the hypothesis that intraperitoneal tonometry can be a specific monitor for ischaemia in the small intestine. METHODS: Twelve pigs were anaesthetized and mechanically ventilated. The celiac artery (CA), the superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA) were identified. Tonometry catheters were positioned intraperitoneally at three different locations where blood supply varied. One at a time of the mesenteric arteries was occluded, producing regional ischaemia in different splanchnic organs. RESULTS: Regional PCO2 (Pr CO2) increased significantly in the intestinal region, in the small intestine, only during the SMA clamping. In the epigastric region, i.e. in the space between the liver and the stomach, PrCO2 increased significantly only during CA clamping. CONCLUSION: Intraperitoneal tonometry in the intestinal region can be a specific monitor of ischaemia in the small intestine. INVESTIGATION: The care and handling of the animals was in accordance with legislation by the Swedish Board of Agriculture.

Anesthesia↗
PubMed2000

A new method of intrathecal PO2, PCO2, and pH measurements for continuous monitoring of spinal cord ischemia during thoracic aortic clamping in pigs.

BACKGROUND: Impaired spinal cord circulation during thoracic aortic clamping may result in paraplegia. Reliable and fast responding methods for intraoperative monitoring are needed to facilitate the evaluation of protective measures and efficiency of revascularization. METHODS: In 11 pigs, a multiparameter PO2, PCO2, and pH sensor (Paratrend 7, Biomedical Sensors Ltd, United Kingdom) was introduced into the intrathecal space for continuous monitoring of cerebrospinal fluid (CSF) oxygenation during thoracic aortic cross-clamping (AXC) distal to the left subclavian artery. A laser-Doppler probe was inserted into the epidural space for simultaneous measurements of spinal cord flux. Registrations were made before and 30 minutes after clamping and 30 and 60 minutes after declamping. The same measuring points were used for systemic hemodynamic and metabolic data acquisition. RESULTS: The mean CSF PO2 readings of 41 mm Hg (5.5 kPa) at baseline decreased within 3 minutes to 5 mm Hg (0.7 kPa) during AXC (P < .01). Spinal cord flux measurement responded immediately in the same way to AXC. Both methods indicated normalization of circulation during declamping. Significant (P < .01) changes were also observed in the CSF metabolic parameters PCO2 and pH. CONCLUSIONS: In this experimental model of spinal ischemia by AXC, online monitoring of intrathecal PO2, PCO2, and pH showed significant changes and correlated well with epidural laser-Doppler flowmetry (P < .01).

Animals↗
PubMed1999

Intraperitoneal and sigmoid colon tonometry in porcine hypoperfusion and endotoxin shock models.

BACKGROUND: The objective of the present study was to assess the accuracy of an air tonometry device in vivo within a wide range of regional carbon dioxide tension (PrCO2) values by using saline tonometry as the standard and to investigate the possibilities to monitor perfusion of the intestine by tonometry in the intraperitoneal cavity. METHODS: Piglets were anesthetized and mechanically ventilated. A pair of tonometry catheters was placed in the sigmoid colon, while another pair was placed intraperitoneally in the right lower quadrant of the abdomen. Air tonometric regional PCO2 (aPrCO2) was measured every 15 min intraperitoneally and every 20 min in the sigmoid colon. Saline tonometric measurements were made every 30 min and steady-state values (ssPrCO2) were derived. Hypoperfusion shock was induced by graded constriction of the aorta. Endotoxin shock was induced by administration of lipopolysaccharide (LPS). RESULTS: The obtained average PrCO2 (=matched (aPrCO2+ ssPrCO2)/2) values ranged from 5.1 kPa to 14.7 kPa. Regional air PCO2 (aPrCO2) and steady-state saline PCO2 (ssPrCO2) exhibited a strong positive linear relationship (r=0.959). The 95% confidence interval of the mean of dPrCO2 (=aPrCO2-ssPrCO2) was 0.31-0.46 kPa. Intraperitoneal tonometric PrCO2 was lower than intraluminal PrCO2 in the sigmoid colon, and was also more sensitive to circulatory changes than sigmoid colon PrCO2. CONCLUSION: The regional air PCO2 (aPrCO2) showed good agreement with the steady-state saline regional PCO2 (ssPrCO2). Intraperitoneal measurements may be an alternative method of monitoring intestinal perfusion after abdominal surgery.

Air↗
PubMed1997

Involvement of the alpha2-adrenergic system in polydipsia in schizophrenic patients: a pilot study.

Animal studies have suggested the involvement of the adrenergic system in drinking behavior. The present study investigated the involvement of the alpha2-adrenergic system in the polydipsia of patients with chronic schizophrenia by use of an alpha2 agonist and an antagonist. Four patients with schizophrenic disorders accompanied by intermittent hyponatremia and polydipsia were the subjects of, and completed, this study. Drinking behavior was assessed by calculating the percent of maximum weight gain [PMWG: (maximum diurnal weight - standard weight) x 100/standard weight]. Standard weight was defined as body weight after 8 h of water restriction. Clonidine (75, 150, and 225 mg/day) increased the PMWG in a dose-dependent manner in the four subjects. In contrast, in three of the subjects, mianserin (30, 60, and 90 mg/day) decreased PMWG, and the severe polydipsia disappeared almost completely. These findings indicate clearly that the alpha2-adrenergic system is involved in the drinking behavior of schizophrenic patients. Mianserin appears to be clinically useful in treating such patients with polydipsia.

Adrenergic alpha-Agonists↗
PubMed1997

Life-threatening dysphagia following prolonged neuroleptic therapy.

We report the cases of two patients with complaints of dysphagia following long-term neuroleptic therapy. Esophageal contrast radiography revealed that one patient suffered disruption of the normal swallowing activity of the pharyngoesophagus due to tardive dyskinesia. Her dysphagia disappeared following changes in her neuroleptic medications and the administration of clonazepam. The other patient demonstrated severe rabbit syndrome involving the glossopharynx. This 3-Hz rhythmic movement disorder resolved following injection of an anticholinergic agent. Thereafter, the addition of oral trihexyphenidyl to her medication regimen improved her dysphagia. It should be emphasized that the differential diagnosis of neuroleptic-associated dysphagia subtypes is important because therapeutic strategies differ depending on the subtype of this life-threatening illness.

Antipsychotic Agents↗
PubMed1997

Transient and intermittent oral dyskinesia appearing in a young woman ten days after neuroleptic treatment.

A 22-year-old woman was admitted to our hospital because she showed psychomotor excitement and signs of schizophrenia following psychological stress. Nine days after neuroleptic medication, she could not eat and exhibited high fever, diaphoresis, excessive salivation, and severe extrapyramidal signs with cogwheel rigidity and resting tremor of the upper extremities. The next day, bucco-linguomasticatory dyskinesia, which is quite similar to tardive dyskinesia, appeared. The dyskinesia lasted intermittently for 6 days. The present case shows that buccolingual dyskinesia can occur even after early neuroleptic exposure in certain patients.

Adult↗
PubMed1996

Involvement of the endogenous opioid system in the drinking behavior of schizophrenic patients displaying self-induced water intoxication: a double-blind controlled study with naloxone.

Previously we found significant suppression of polydipsia in a schizophrenic patient with PIP syndrome (psychosis, intermittent hyponatremia, and polydipsia). Suppression was obtained with a small dose of naloxone injected once every 2 weeks in long-term repeated studies. We attempted to confirm the effect of naloxone on PIP syndrome by using a double-blind controlled study. The body weights of eight schizophrenic inpatients with PIP syndrome were checked five times daily, and the maximum weight gain during 1 day was chosen as an index of their polydipsia. Naloxone (0.6 mg in three divided doses) or placebo (saline) injection was given once every 2 weeks three times. Assignment to either the naloxone or placebo series was done randomly in a double-blind, crossover design. Naloxone decreased the maximum weight gain per day significantly in five cases. However, naloxone also increased weight gain significantly in three cases. There was no correlation of the weight-increasing effect of naloxone with the duration and intensity of excessive drinking. Our findings showed that the endogenous opioid system might be related to compulsive drinking behavior in the PIP syndrome and that opioid antagonists such as naloxone or naltrexone could be useful in the therapy of PIP syndrome.

Adult↗
PubMed1996

Prevalence of and risk factors for respiratory dyskinesia.

We explored the prevalence of respiratory dyskinesia (RD), diagnosed objectively using a spirograph, and the major risk factors for tardive dyskinesia (TD) and RD. A total of 258 inpatients treated with neuroleptics was interviewed, and TD was evaluated using the Abnormal Involuntary Movement Scale (AIMS). Movement of the chest and respiratory regularity were assessed on clinical examination. Spirographs of patients with suspected RD were recorded, and RD was diagnosed based on spirographic data and the concurrence of two investigators. The prevalence of TD in this study was 22.1% (57 of 258). Aging and organic brain damage (OBD) were confirmed as risk factors; female gender, mood disorders, and the duration of neuroleptic exposure were not. Ten of 28 patients suspected of having RD were diagnosed with RD on the basis of persistent respiratory irregularities without other physiologic causes. The overall prevalence of RD was 3.9% (10 of 258) and was 17.5% (10 of 57) among the TD patient population. Four of these patients complained of dyspnea, and three demonstrated grunting. RD was more highly associated with aging and OBD than with TD itself. The identification of risk factors for RD is not only helpful in planning prophylactic strategies, but also facilitates the understanding of the pathogenesis of this syndrome.

Adult↗
PubMed1994

Naloxone attenuates drinking behavior in psychiatric patients displaying self-induced water intoxication.

1. The present study was performed to examine the effect of naloxone on drinking behavior in three schizophrenic inpatients with psychosis, intermittent hyponatremia, and polydipsia. 2. Their body weight were checked five times daily and the maximum weight gain during a day was chosen as an index of their polydipsia. 3. After control recording for six weeks, a daily naloxone (0.6 mg) injection series was performed once every two weeks for three series (six weeks). Withdrawal of this drug for six weeks resulted in weight gain recovering to control level. 4. The present study showed that naloxone seems to be a potential treatment for psychiatric patients displaying self-induced water intoxication and that endogenous opioid systems are involved in the compulsive drinking behavior of this syndrome.

Drinking Behavior↗
PubMed1992

Naloxone attenuates drinking behavior in a schizophrenic patient displaying self-induced water intoxication.

This study was performed to examine the effect of naloxone on drinking behavior in a schizophrenic inpatient with psychosis, intermittent hyponatremia, and polydipsia (PIP syndrome). His body weight was checked five times daily, and the maximum and minimum weight gains during a day were chosen as an index of polydipsia. Both daily (0.6 mg) and repeated (0.6 mg for 6 days) injections of naloxone suppressed his weight gain significantly for 2 weeks. Withdrawal of the drug for 4 weeks resulted in weight gain recovering to control level. Thereafter, a second trial was performed to examine the long-term effect of this treatment. A daily naloxone (0.6 mg) injection series was performed once every 2 weeks for six series (12 weeks). This drug regimen also suppressed his weight gain in a continuous fashion. The study showed that naloxone seems to be a potential treatment for PIP syndrome and that endogenous opioid systems play a part in the compulsive drinking behavior of the PIP syndrome.

Drinking Behavior↗
PubMed1992

Distinguishing acute and tardive akathisia by monitoring microvibration: a pilot study.

One acute and one tardive akathisia patients, respectively, and 10 neuroleptic-treated schizophrenic patients were injected with biperiden 5 mg or saline and the response to anticholinergics was monitored by microvibration (MV) as an indicator of muscle tonus. These data were subjected to the Fast Fourier Transform and an averaged power spectrum was computed. The biperiden injection markedly reduced the power spectral values of MV in acute akathisia. In contrast with acute akathisia, the biperiden injection significantly increased the power spectral values of MV in tardive akathisia. The subjective feelings of akathisia patients were parallel to the power spectral values of MV. Control patients were not affected by such treatment. The present findings show that the subjective symptoms of akathisia can be well defined by the objective, differential response to anticholinergics in a manner similar to the visible extrapyramidal symptoms (dystonia, dyskinesia) induced by neuroleptics.

Acute Disease↗
PubMed1992

Respiratory dyskinesia: a variety of clinical forms differentially diagnosed by using a spirograph.

Four cases of respiratory dyskinesia were investigated by using a spirograph before and after biperiden injection. The abnormal respiratory patterns in four cases appeared to be in two types and these abnormalities were abolished after biperiden injection. The present study showed that respiratory dyskinesia could be defined more clearly by using a spirograph and these results are useful for the diagnosis of patients with respiratory discomfort while undergoing neuroleptic drug treatment.

Adult↗
PubMed1991

Evidence for a direct adverse reaction of neuroleptics in self-induced water intoxication of psychiatric patients.

A mentally retarded patient who developed polydipsia and hyponatremia following the long-term use of neuroleptics is described. Before the investigation, he was treated with a combination of five drugs: diazepam, propericiazine, carbamazepine, lithium carbonate and trihexyphenidyl. The treatment was switched to diazepam alone; to propericiazine, trihexyphenidyl and diazepam; to carbamazepine and diazepam; and finally to lithium carbonate with diazepam. Under the five drug treatment protocols, his weight gains during the day were monitored, every day as an index of the water he drank in the day time. The combination of the five drugs caused the greatest weight differences per day and the other drug regimens, except diazepam alone, seemed to increase the weight differences to some extent. These findings indicate that a drug combination such as the neuroleptics, lithium and carbamazepine used for emotional stabilization must be carefully monitored to avoid the induction of compulsive drinking.

Adult↗
PubMed1990

Chronic treatment with talipexole dihydrochloride on abnormal involuntary movement in humans.

Two cases of severe dystonia and dyskinesia were treated with talipexole, a dopamine autoreceptor agonist, and the metabolites of dopamine, norepinephrine, and serotonin in cerebrospinal fluid (CSF) were determined. Despite significant reductions in these metabolites in CSF, behavioral amelioration of these cases could not be observed. The present findings argue for further studies to explore the clinical usefulness of dopaminergic agonists such as talipexole.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Treatment of tardive akathisia with clonidine.

Two cases of tardive akathisia, which were misdiagnosed as anxiety originating from a schizophrenic disorder, had been treated with anxiolytics in addition to neuroleptics and anticholinergics. The diagnoses were changed to tardive akathisia, the anticholinergics were discontinued, and the patients were treated with clonidine successfully. In view of the similar effects of clonidine and anticholinergics, the pathophysiology of tardive akathisia must be very similar to that of tardive dyskinesia.

Adult↗