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Biomedical subjects

S Dohi

Publications and source records attributed to S Dohi.

At least 163 records · Page 9Linked to original sources
PubMed1991

[Venous air embolism following repositioning from sitting to supine].

We have experienced a patient in whom venous air embolism reoccurred, when the patient's position was changed from sitting to supine. A 40 year old male with Arnold-Chiari malformation underwent suboccipital decompression and cervical laminectomy under the sitting position. During surgery, three episodes of venous air embolism were detected by high pitched sound through precordial ultrasound Doppler stethoscope, an abrupt increase in pulmonary arterial pressure, a decrease in end-tidal carbon dioxide concentration; and a small amount of bubbled air was removed from the central venous catheter. At the end of surgery when the patient was turned to supine position, the signs of venous air embolism reappeared and 3 ml of bubbled air was also removed. This case suggests that there is some remaining air in the large veins of the upper part of the body once the air embolism has occurred during sitting position and thus we need to confirm that no air is left in the large veins before repositioning. We should be cautious of reoccurrence of venous air embolism whenever patient's position is changed.

Adult↗
PubMed1991

[Hemodynamic effects of lung inflation during bilateral and single lung ventilation--a clinical investigation].

Hemodynamic changes during positive airway pressure ventilation is well known. To compare changes of hemodynamic variables during one-lung inflation with those during two-lung inflation, we studied the effects of lung inflation on hemodynamic changes in 15 anesthetized patients who were intubated endobronchially. When the airway pressure was increased from 0 cmH2O to 10, 20, 30 cmH2O, systolic pressure decreased gradually and central venous pressure increased during both two-lung and one-lung inflations (P less than 0.05). During one-lung inflation, the decrease in arterial pressure relative to apneic arterial pressure was significantly less than those during two-lung inflation at each level of airway pressure (P less than 0.05). During one-lung inflation, central venous pressure which was higher relative to apneic central venous pressure, and was less than that during two-lung inflation at 30 cmH2O (P less than 0.05). Heart rate was unchanged during both two and one-lung inflations compared with apneic heart rate. We conclude that during one-lung inflation, systolic pressure and central venous pressure are influenced less by the increased airway pressure than during two-lung inflation. The results indicate that during one lung ventilation, lungs inflated with clinically accepted levels of airway pressure do not depress the systemic circulation, but when the airway pressure during one-lung inflation (like a leak test) exceeded over 30 cmH2O, a significant depression of the systemic circulation occurs.

Aged↗
PubMed1991

[Effects of enflurane on the elastic properties of frog skinned skeletal muscle fiber under relaxed and rigor conditions].

We studied the effects of enflurane on the elastic property of the mechanical skinned fiber prepared from M. Semitendinosus of bullfrog. Longitudinal and lateral elastic properties of the skinned fibers were measured under relaxed and rigor conditions to clarify the effects of enflurane on actomyosin complex. Under the rigor condition, enflurane did not change the lateral elasticity of the fibers, but enflurane decreased the longitudinal elasticity. On the other hand, under the relaxed condition, enflurane did not change the elasticity. The results suggest that enflurane probably decreases the force of binding of cross-bridges to actin, which is one of the factors to reduce the maximal force.

Animals↗
PubMed1990

Clinical evaluation of clonidine added to lidocaine solution for epidural anesthesia.

The effects of clonidine added to lidocaine solution used for epidural anesthesia were assessed in 92 women scheduled for surgery and premedicated with diazepam 10 mg po. Patients received 18 ml 2% lidocaine with clonidine 5 micrograms.ml-1 (group C-5, n = 26), with clonidine 10 micrograms.ml-1 (group C-10, n = 20), with epinephrine 5 micrograms.ml-1 (group E, n = 26), or plain (group P, n = 20). No significant difference in the number of segments of analgesia was found at any observation period among the four groups of patients. The decreases in mean blood pressure (BP) observed 20 min after epidural injection in those given clonidine (5 +/- 8% for C-5, 10 +/- 11% for C-10, mean +/- SD) were similar to those given plain lidocaine (7 +/- 12%) but significantly less than those given epinephrine (18 +/- 12%, P less than 0.01 vs. C-5 or P). The response of BP to ephedrine given for restoring BP during anesthesia was not attenuated in patients who received epidural clonidine. Heart rate (HR) decreased significantly in patients given clonidine 10 micrograms.ml-1 (7 +/- 8%, P less than 0.01), but not in those given clonidine 5 micrograms.ml-1, whereas HR increased significantly in those given lidocaine plain or with epinephrine (10 +/- 8% and 28 +/- 14%, respectively, P less than 0.01). The incidence of sinus bradycardia was similar among the four groups of patients. Significant differences were also observed in sedation score between clonidine groups and groups P or E; sedation appeared approximately 10-20 min after epidural injection in both clonidine groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Hemodynamic status susceptible to slowing of heart rate during thermodilution cardiac output determination in anesthetized patients.

To identify hemodynamic variables that might indicate susceptibility to slowing of heart rate (HR) and to mean arterial pressure (MAP) decrease caused by cold injectate during thermodilution (TD) cardiac output determination, we measured hemodynamic variables in 32 anesthetized patients undergoing major surgery. A total of 608 cardiac output determinations were evaluated for any relationship between the magnitude of HR decreases and basal hemodynamic variables. The magnitude of HR decrease was pronounced in low cardiac index (CI), low mean pulmonary artery pressure (MPAP), and high systemic vascular resistance index (SVRI). Although there was some decrease in MAP associated with cold injectate, neither changes in SVRI nor those in the other hemodynamic variables correlated with the decreases in MAP. These results suggest that decreased CI and MPAP associated with elevated SVRI may be more susceptible to slowing of HR during cardiac output determination by TD in anesthetized patients.

Adult↗
PubMed1990

Effects of cocaine on pial arterioles in cats.

We used the closed cranial window technique to observe the responses of pial arterioles to topical application of cocaine in 29 anesthetized cats. Alterations in arteriolar diameter were dependent on the concentration of cocaine applied. Cocaine dissolved in artificial cerebrospinal fluid at concentrations of 10(-8) or 10(-7) M was without effect. Concentrations of 10(-6) and 10(-5) M produced dilation (4.9 +/- 1.5% [mean +/- SEM] and 5.9 +/- 2.0%, respectively) in large arterioles (greater than 100 microns) but no significant change in the diameter of small arterioles (less than 100 microns). A concentration of 10(-4) M dilated both large and small arterioles (20.3 +/- 3.1% and 12.0 +/- 7.1%, respectively). Pretreatment with 1 mg/kg i.v. propranolol blocked the increase in pial arteriolar diameter after application of 10(-4) M cocaine and produced significant vasoconstriction in small arterioles (-8.3 +/- 3.1%). Cocaine produces vasodilation of cat cerebral arterioles. This effect appears to be mediated, at least in part, by mechanisms that depend on stimulation of beta-adrenergic receptors.

Administration, Topical↗
PubMed1990

Biological assessment of the enhancement of tritium excretion by administration of diuretics and excessive water in mice.

This study was undertaken to determine whether or not the administration of diuretics and excess water after tritium exposure would have any positive reducing effect not only on the retention of tritium but also on the radiation damage of hematopoietic tissue in mice. When mice were treated with diuretics and excess water for a few days after injection of tritiated water (HTO), radioactivity within the body fluid and tissues was reduced, and the number of CFU-s, clonability of splenic T cells and proliferative activity assayed by Con-A blastogenesis were increased in comparison with those in the controls. When the mice were injected with a large dose of HTO (811 MBq/mouse) to assay survival, no mice treated with diuretic and excess water died 80 days after injection, while 80% of the controls died during the first month. The final committed dose in the mice treated early with diuretics was calculated to be 60% of that in the controls. These results suggest that treatment with diuretics and excess water is useful for practical purposes when a human is accidentally exposed to tritium.

Animals↗
PubMed1990

[The effects of a small dose of atropine upon sinus bradycardia during spinal anesthesia].

Positive or negative chronotropic effects of atropine and their magnitude are known to be determined by its dose given, concomitant sympathetic tone, and patient's age. Thus, the aim of the present study is to investigate the small effective dose of atropine for acceleration of heart rate in sedated bradycardic patients under spinal anesthesia, and to evaluate the relationship between the heart rate response to atropine and level of analgesia or patient's age. Significant increases in heart rate were observed in patients receiving intravenous atropine 4 micrograms.kg-1 (n = 21) or 6 micrograms.kg-1 (n = 35) except 2 micrograms.kg-1 (n = 18). However, there were wide variations in cardiac responses to atropine among patients in each group. Negative chronotropic responses to atropine were elicited in 10 (56%), 2 (9%), and 1 (3%) of the patients receiving 2 micrograms.kg-1, 4 micrograms.kg-1 and 6 micrograms.kg-1, respectively. Although there was no correlation between the heart rate response to each dose of atropine and the level of spinal anesthesia, the magnitude of positive chronotropic response to atropine of 6 micrograms.kg-1 related inversely with age. The present results suggest that atropine above 4 micrograms.kg-1 is required to accelerate the heart rate in most bradycardic patients under spinal anesthesia irrespective of the level of analgesia. However, it seems appropriate to administer atropine intravenously in a cumulative fashion, because of individual's variability including age in the chronotropic response to atropine.

Adult↗
PubMed1990

[Evaluation of noninvasive monitoring of preoxygenation].

Administration of 100% oxygen before a "rapid-sequence" induction of anesthesia is recommended to prevent hypoxemia during induction. In the present study, we used a laser scattering analyzer to study the effectiveness of nitrogen washout from the lungs with oxygen wash into the lungs under two different preoxygenation regimens; 4 times of maximal breathing of 100% oxygen in one minute and normal tidal breathing of 100% oxygen for 3 minutes. The volunteers were healthy, ASA physical status 1, 22 to 33 years of age (26 +/- 3), 167 +/- 5 cm tall, and weighing 60 +/- 5 kg. Arterial blood saturation measured by a pulse oximeter was 97 while breathing 21% oxygen, and 99% while breathing 100% oxygen. Arterial oxygen tensions were 98 mmHg while breathing 21% oxygen, and over 480 mmHg while breathing 100% oxygen. Arterial carbon dioxide and end tidal carbon dioxide concentrations indicated that 4 time of maximal breathing in a minute leads to hyperventilation. The end-tidal oxygen concentration was not significantly different between before and after oxygen administration in two different regimens. End-tidal nitrogen concentration after tidal volume ventilation was lower than that of 4 breath in a minute. These results indicate that end-tidal nitrogen and oxygen could reflect arterial nitrogen and oxygen tensions during preoxygenation.

Adult↗
PubMed1989

Determination of in vivo and in vitro radiosensitivity of mouse splenic T-lymphocytes using a T-cell cloning technique.

Recently the authors established a method for culturing mouse splenic T-lymphocytes with T-cell growth factor (TCGF) and feeder cells in vitro. Using this method, T-lymphocytes grow for approximately 14 days with population doubling times of 27-29 hr; cloning efficiencies (CEs) of mouse spleen cells ranged from three to twelve percent. Using this colony forming assay, in vivo and in vitro radiosensitivity of mouse splenic T-lymphocytes in the G0 phase and in vitro radiosensitivity of proliferating T-lymphocytes (cycling T-lymphocytes) were examined. For in vitro irradiation, the dose-survival curve of T-lymphocytes in G0 phase gave a D0 value of 0.99 Gy and a Dq value of 0.87 Gy and that of cycling T-lymphocytes gave a D0 value of 1.04 Gy and a Dq value of 0.19 Gy. For in vivo irradiation, the dose-survival curve of T-lymphocytes gave a D0 value of 1.01 Gy and a Dq value of 0.73 Gy. These results suggest that the recovering activity from sublethal damage of G0 T-lymphocytes was more effective than that of cycling T-lymphocytes. Furthermore, this colony forming assay system appears to be very useful for screening the effects of in vivo exposure to toxic and/or mutagenic agents and for comparing the effects of in vivo exposure with those of in vitro exposure to toxic agents as well as radiation.

Animals↗
PubMed1989

Alteration of pulmonary oxygenation by pulmonary artery occluded pressure measurements in mechanically ventilated patients.

A significant decrease in PaO2 occurs in some patients during PAOP measurements. To examine the incidence and the types of patients whose PaO2 decreases during PAOP measurements, we studied the changes of PaO2 in 101 anesthetized, mechanically ventilated adult patients. During a 2-min inflation of a PAC balloon, seven patients (6.9 percent) developed marked decrease in PaO2/FIo2 (more than 100 mm Hg). Neither age nor size of patients, decrease in end-tidal CO2, nor baseline value of PAP correlated with the decreases in PaO2. A decrease in PaO2/FIo2 (more than 50 mm Hg) was observed more frequently in female patients and in patients with cardiac disease, especially those whose PAP values were above normal. Although a significant decrease in PaO2 during PAOP measurements does not appear to occur often, our results suggest that the changes in PaO2 should be evaluated in patients with severely compromised pulmonary oxygenation.

Adult↗
PubMed1989

[An analysis and evaluation of anesthetic consultations for patients undergoing elective surgery].

We reviewed 212 patients whom we consulted before elective surgery concerning their indications of operation and anesthetic risks for the last 18 month periods. Patients' ages were between 6 months to 89 years old, and 46% of the patients consulted were over 60 years of age. Main medical problems related to anesthetic risks included cardiovascular problems (36% of patients), respiratory problems (14%), the abnormality of metabolism or endocrine (8%), hepatic dysfunction (8%), and so on. Most of the patients with ischemic heart disease, hypertension, dysrhythmia, or dysfunction of respiratory system, were over 60 years of age. Those with diabetes mellitus, dysfunction of liver or kidney, or anemia were over 40 years of age. Those with convulsion or congenital heart disease were under 19 years of age. In attempting anesthetic evaluations, patients were assessed according to ASA physical status classification; class I (3%), class II (56%), class III (36%), class IV (5%). Although there was no patient who had intraoperative cardiac arrest or death related to anesthesia, postoperative mortality within 3 months were 19% for ASA class III patients and 60% for class IV. And all ASA IV patients who received their operation died postoperatively. In patients who were classified as ASA III or IV, we feel it is better to add more detailed classification such as Goldman's classification in addition to physical status classification of ASA for preanesthetic assessments of patients, because the majority of patients were elderly with life-threatening complications of cardiovascular and/or respiratory systems.

Anesthesia↗
PubMed1989

[Influence of four opioids on pulmonary oxygenation and naloxone's effects in mechanically ventilated dogs].

In order to examine effects of opioids on pulmonary oxygenation during constant ventilation, we investigated changes in PaO2 following four different opioids and after reversal with naloxone in mechanically ventilated, lightly anesthetized dogs. The systemic administration of morphine 1.0mg.kg-1, buprenorphine 0.03mg.kg-1, butorphanol 0.1mg.kg-1, and cyclazocine 0.05mg.kg-1, did not affect PaO2, although these opioids decreased mean arterial pressure and heart rate significantly. Naloxone 0.04mg.kg-1 after four opioids affected the hemodynamics, significantly, but it did not cause any detrimental effects on pulmonary oxygenation. Although naloxone alone did not affect mean arterial pressure and heart rate at all, subsequent morphine decreased mean arterial pressure and heart rate significantly. Neither naloxone nor subsequent morphine produced any change in PaO2. The results suggest that reversal with naloxone may not cause any significant influences on pulmonary oxygenation in mechanically ventilated and anesthetized patients.

Animals↗
PubMed1989

[The effects of ephedrine and phenylephrine on arterial partial pressure of oxygen].

The changes in arterial partial pressure of oxygen were studied following intravenous injections of either ephedrine, 0.2mg.kg-1, or phenylephrine 2.5 micrograms.kg-1, to restore arterial hypotension. Eighty one adult patients underwent general anesthesia, being mechanically ventilated, were divided into two groups; both lung ventilation group (68 patients) and one lung ventilation group (13). In both lung ventilation group, PaO2/FIO2 changed from 390 +/- 132 to 400 +/- 137 mmHg, and 428 +/- 124 to 438 +/- 136 following administrations of ephedrine and phenylephrine, respectively. The results were not statistically significant. In the one lung ventilation group, PaO2/FIO2 did not change significantly from 190 +/- 45 to 186 +/- 29 with ephedrine and 267 +/- 138 to 317 +/- 230 with phenylephrine. We observed neither arrhythmia, severe hypoxemia, nor decrease in PaO2/FIO2 by more than 100mmHg. These results indicate that with respect to changes in arterial partial pressure of oxygen, the clinical doses of ephedrine and phenylephrine can be safely administered to patients under general anesthesia to restore arterial hypotension.

Adult↗
PubMed1989

Comparison of arterial baroreflex function in humans anesthetized with enflurane or isoflurane.

To compare the depressive effects of isoflurane and enflurane on the arterial baroreflex function, we examined baroreflex control of heart rate during the entire course of clinical anesthesia. Isoflurane and enflurane were found to have similar depressive effects on the baroreflex control of heart rate when used in combination with N2O and O2. Suppression in the baroreflex sensitivity, defined by the slopes of regression line (change in msec of RR interval per mm Hg increase or decrease in systolic blood pressure) was from 7.1 +/- 3.9 to 1.8 +/- 0.7 msec/mm Hg in patients given isoflurane and from 7.8 +/- 4.3 to 3.0 +/- 1.9 msec/mm Hg in those given enflurane when evaluated by a pressor test (bolus IV phenylephrine). The slope of the depressor test (bolus IV nitroglycerin) also decreased from 4.7 +/- 2.8 to 1.9 +/- 1.5 msec/mm Hg with isoflurane and from 5.6 +/- 3.2 to 2.3 +/- 1.2 msec/mm Hg with enflurane. During surgery in which anesthetic concentration invariably needed to be increased, the suppression of the baroreflex sensitivity remained unchanged in both groups of patients. During recovery, the arterial baroreflex function in patients given isoflurane recovered more rapidly than that in patients given enflurane. This difference may be related to a more minor degree of suppression of isoflurane on the autonomic nervous system compared to enflurane.

Adult↗