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Biomedical subjects

S T Ho

Publications and source records attributed to S T Ho.

At least 127 records · Page 7Linked to original sources
PubMed1993

[Correlation between tyndallometry with the "laser flare cell meter" in vivo and biochemical protein determination in human aqueous humor].

INTRODUCTION: The laser flare-cell meter allows noninvasive measurement of aqueous flare in humans. In vitro studies have shown good correlations between flare values and albumin concentrations. In this study, we compared aqueous flare values and aqueous protein concentrations in living human eyes. PATIENTS AND METHODS: We measured aqueous flare and the total aqueous protein concentration in 52 eyes of 52 patients (age 58.4 +/- 18.8 years) that underwent cataract extraction (22 eyes) or trabeculectomy (30 eyes). Before surgery, aqueous flare was determined with the laser flare-cell meter (Kowa FC-1000). During surgery, 50 microliters of primary aqueous humor was aspired, and total aqueous protein concentration was performed using a modified Pierce-BCA assay. Linear regression analysis was calculated. RESULTS: There was a high correlation between aqueous flare values and total aqueous protein concentration (y = 0.52x + 0.15, r = 0.98, p < 0.00001). This correlation was observed both in eyes with and without cataract. CONCLUSION: Our results indicate that aqueous flare values as determined with the laser flare-cell meter reflect the true aqueous protein concentration quite accurately. Lens opacities appear not to significantly alter the results of aqueous flare measurements. As expected by theoretical assumptions, flare measurements overestimate aqueous protein concentrations in eyes with severely impaired blood-aqueous barriers because, according to Rayleigh's law, larger protein molecules cause more light scattering. However, transformation and expression of flare values as "albumin concentration equivalents" according to in vitro-calibration may still be useful, especially if the results of different instruments are to be compared.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Evaluation of gastric emptying in severe, burn-injured patients.

OBJECTIVE: The aim of this study was to evaluate the possible effect of a severe burn on gastric emptying by determining the absorption kinetics of orally administered acetaminophen. DESIGN: A prospective, controlled study. SETTING: A ten-bed burn center in a 1,300-bed university hospital. PATIENTS: Ten adult patients suffering from second-degree burn involving > 20% of total body surface area and 20 normal, healthy volunteers who acted as controls. INTERVENTIONS: Patients received routine treatment such as nutritional support and cimetidine. However, opiates were stopped for at least 12 hrs before the start of the study, and nonsteroidal anti-inflammatory drugs as alternatives were used. After an 8-hr fast, the subjects ingested 0.5 g acetaminophen with 200 mL of water. The plasma concentrations of acetaminophen were determined by high-performance liquid chromatography, and the absorption kinetics was estimated from determination of time to reach the maximum plasma concentration, the maximum plasma concentration, and the area under the plasma concentration-time curve. MEASUREMENTS AND MAIN RESULTS: The mean time for reaching the maximum plasma concentration was 33 +/- 24 (SD) mins in patients and 39 +/- 24 mins in the healthy volunteers. The mean area under the plasma concentration-time curve from time 0 to 120 mins and the mean maximum plasma concentration were 556 +/- 190 micrograms/mL/min and 9.5 +/- 3.5 micrograms/mL in patients, and 539 +/- 131 micrograms/mL/min and 7.8 +/- 2.8 micrograms/mL in volunteers, respectively. There was no statistical difference between groups in the time to reach the maximum plasma concentration, the area under the plasma concentration-time curve from time 0 to 120 mins, and the maximum plasma concentration. The time for reaching the maximum plasma concentration was not correlated with the severity of the burn (% area of burn) and the duration of healing (days) after burn. CONCLUSIONS: We conclude that severe burn injury does not affect the kinetics of gastric emptying, and that 200 mL of water ingested 2 hrs before anesthesia is quite safe in severely burned patients. Also, the absorption kinetics of acetaminophen was not altered by burn injury.

Absorption↗
PubMed1993

Reinduction of the hypnotic effects of thiopental with NSAIDs by decreasing thiopental plasma protein binding in humans.

The effects of 14 non-steroidal anti-inflammatory drugs (NSAIDs)--naproxen, ibuprofen, mefenamic acid, ketoprofen, indomethacin, fenoprofen, diclofenac sodium, aspirin, salicylic acid, piroxicam, sulindac, fenbufen, flurbiprofen and benzydamine, on the plasma protein binding of thiopental and the clinical consequences of such interactions were studied. Four of them, naproxen, ibuprofen, salicylic acid and aspirin, very significantly decreased the protein binding of thiopental in vitro in human plasma (P < 0.005). Structurally, they were salicylates and propionic acid derivatives among the six classes of NSAIDs studied. The aspirin study demonstrated that the protein-displacing phenomenon was temperature-dependent, and concentration-dependent. Clinically, aspirin administered intravenously resulted in a significant increase in the percentage of plasma free thiopental from 16.01 +/- 3.59% to 22.27 +/- 3.96% (P < 0.001, n = 10) in patients undergoing surgery, and resulted in three of seven patients sleeping again during recovery from thiopental-induced anesthesia. Although the effect of chronic use of NSAIDs before anesthesia is uncertain, studies should be carried out to find out if naproxen, ibuprofen, and aspirin influence the depth of anesthesia, time of recovery and duration of action of thiopental.

Adult↗
PubMed1993

[Total intravenous anesthesia with O2 mask in transthoracic endoscopic sympathectomy for palmar hyperhidrosis].

Using non-invasive monitors (such as blood pressure, O2 saturation, end-tidal CO2 pressure monitors and electrocardiograms), the application of total intravenous anesthesia with O2 mask in transthoracic endoscopic sympathectomy was evaluated. A total of 198 palmar hyperhidrosis patients were studied. In the study, the durations of surgery were 5-15 min (mean 8 min) with anesthesia duration of 8-20 min (mean 12 min), respectively. The cardiovascular system was quite stable during operation, with systolic blood pressures of 90-165 mmHg (mean 132 mmHg), diastolic blood pressures of 50-106 mmHg (mean 92 mmHg) and heart rates of 56-130 beats/min (mean 104 beats/min). The respiratory function was maintained within a safety range with O2 saturation of 95-100% (mean 99%) and end-tidal CO2 pressure of 32-40 mmHg (mean 36 mmHg). After surgery, the major discomfort was chest pain (132/198), but this could be improved with intravenous analgesics. Patients' consciousness returned within 1-3 min. After ensuring their general condition was stable, patients were discharged within 24 hr. Preliminary study showed that total intravenous anesthesia plus muscle relaxant, with O2 mask and assisted ventilation, could serve as a safe and simple anesthesia for palmar hyperhidrosis patients who received transthoracic endoscopic sympathectomy.

Adolescent↗
PubMed1992

Relationship between cardiovascular functions and ionic hypocalcemia induced by citrate infusion in anhepatic swines: CaCl2 therapy in severe ionic hypocalcemia.

Baseline and serial values of serum [Ca++], [K+], [Na+], arterial blood gas tensions, acid-base status, temperature and hemodynamic functions were measured during infusion of citrate-phosphate-dextrose (CPD) solution (0.35 ml.kg-1 x min-1) in anhepatic pigs of three randomized groups. Thirteen pigs (group I) continued to receive intravenous infusion of CPD solution until cardiac arrest. When mean arterial pressure (MAP) decreased to about 50 mmHg (group II, n = 7), or 40 mmHg (group III, n = 7) infusion of CPD solution was discontinued, and pigs received CaCl2 (20 mg/kg) intravenously. Serial (1, 4, 8, and 12 min after CaCl2 administration) values of all the above variables and serum citrate at baseline and lowest [Ca++] were measured. After hepatectomy and venovenous bypass, cardiac output (CO) decreased 30%. When ionic hypocalcemia was above 0.7 mM, there was no significant change of cardiovascular functions. When [Ca++] was between 0.34-0.7 mM, there were linear relationships between [Ca++] and CO, systemic vascular resistance (SVR) and MAP, respectively. When [Ca++] was below 0.34 mM, cardiovascular functions decreased abruptly, and the pigs died at [Ca++] of 0.26 +/- 0.06 mM. When [Ca++] decreased to 0.36 +/- 0.06 mM and MAP to 50 +/- 4 mmHg, most hemodynamic functions could be reversed by calcium therapy. However, when [Ca++] decreased to 0.33 +/- 0.05 mM and MAP to 40 +/- 2 mmHg, hemodynamic functions could not be reversed by calcium therapy alone.

Animals↗
PubMed1992

Different sensory blockade of interscalene versus axillary approach of brachial plexus block.

We examined results of brachial plexus block in 31 young male patients who underwent upper extremity surgical procedures. Interscalene block was performed using a paresthesia technique in 13 patients and axillary block, using the perivascular technique, in 18 patients. In both groups, 30 ml 1.5% lidocaine with 1:200,000 epinephrine was injected. Sensory blockade was evaluated at 5 min and 15 min after injection, determined by pinprick. Results showed that the interscalene technique preferentially blocked the cephalad nerves while the axillary technique produced similar block of both cephalad and caudal nerves of the brachial plexus. Difference between groups was statistically significant, suggesting that the extent of nerve block depends on the technique of approach per se. The difference in patterns of nerve blocked by either technique could be due to the access of local anesthetic to the different components of plexus in the sheath.

Adult↗
PubMed1992

Partially endothelium-dependent relaxing effect of ketamine on the canine basilar artery in vitro.

The influence of the endothelium on the vasodilator effect of ketamine and its possible mechanism of action on intracellular calcium levels were investigated. We conducted experiments in vitro on canine basilar arteries precontracted with 5-HT and with potassium at high concentrations. Ketamine (10(-6) to 10(-3) M), added cumulatively, relaxed both 5-HT and high-K(+)-induced contraction of basilar arteries (with or without endothelium) in a dose-dependent manner. The ED50s of ketamine for relaxation of 5-HT and high-K(+)-induced contraction for intact endothelium were 3 x 10(-4) M and 6 x 10(-4) M, respectively, and for denuded preparations, 7 x 10(-4) M and 15 x 10(-4) M, respectively. Methylene blue, which blocks the release and/or the effect of endothelium derived relaxing factor, significantly attenuated the relaxation effect of ketamine on the basilar artery. Our results indicate that the endothelium may be responsible for a part of the vasodilator effect of ketamine. We also examined the effect of pretreatment of basilar artery with ketamine (5 x 10(-4) M) on intracellular calcium levels when contraction was induced by 5-HT or by high K+ concentrations. Ketamine significantly inhibited the phase of the contraction induced by high K+. Thus, the vasodilator effect of ketamine may be mediated by inhibition of calcium influx and by the release of EDRF.

Animals↗
PubMed1992

[Comparison of anesthetic morbidity and mortality before and after the implementation of quality assurance in Tri-Service General Hospital].

The desire to improve anesthetic outcome is a cornerstone in modern anesthesia. There are many means to reach this goal, such as enforcement in personal training, elevation of monitoring standards, constant vigilance and stern quality assurance (QA). The department of Anesthesiology, Tri-Service General Hospital, has adopted the QA program and implemented it since March 1, 1990. Because there were no significant differences in terms of personnel training, monitoring standards and types of anesthesia and surgery before and after the application of QA program, we investigated the effects of QA on anesthetic major morbidity and coma/mortality. We analyzed the anesthetic results obtained in two separate periods respectively spanning from Jan. 1, 1989 to Dec. 31, 1989 and from Mar. 1, 1990 to Feb. 28, 1991. During the first two months of 1990, the department's personnel were trained to be familiar with the QA program. We compared the anesthetic major morbidity and coma/mortality of one year before the implementation of QA with those in a one-year period after its implementation. Before and after enforcement of QA, there were no significant differences (p greater than 0.05) regarding major morbidity and coma/mortality, but the rates of anesthetic complications were lower after the practice of QA program. Since the functions of QA was aimed at alerting the anesthetic personnel to keep constant vigilance over the act of anesthesia, QA in theory could reduce anesthetic accidents and mishaps related jointly to surgery and anesthesia. The reason why QA did not decrease anesthetic major morbidity and coma/mortality in this study may be due to limited number of anesthesia in relatively short period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Determination of buprenorphine by high-performance liquid chromatography with fluorescence detection: application to human and rabbit pharmacokinetic studies.

A rapid, sensitive, precise and accurate high-performance liquid chromatographic assay with fluorescence detection was developed for the determination of buprenorphine in human, rabbit, pig and dog plasma. It is comprised of only a one-step extraction procedure with hexane-isoamyl alcohol at pH 9.25 and reversed-phase chromatography on a muPorasil column. The recoveries of buprenorphine and nalbuphine (internal standard) were greater than 90%. Calibration graphs were linear over the concentration range 3-300 ng/ml with a coefficient of variation, both within-day and between-day, of less than 9% at any level. The limit of detection was 1.0 ng/ml of plasma based on a signal-to-noise ratio of 3. Eight other clinically used narcotics were investigated to check for potential interferences and their analytical conditions. The possible decomposed compounds of buprenorphine were also checked for the specificity of this assay. The method has been successfully applied to the stability and pharmacokinetic studies of buprenorphine. Buprenorphine in plasma did not decompose significantly at -20 degrees C for four weeks. Pharmacokinetic application in six rabbits and a surgical patient revealed that buprenorphine followed a linear three-compartment model with two distribution phases. The two distribution and elimination half-lives and the clearance of buprenorphine were 1.32, 24.8 and 230 min and 224 ml/min in human plasma, and 0.94, 12.5 and 232 min and 30 ml/min in rabbit plasma.

Animals↗
PubMed1991

Effects of temperature on cutaneous microcirculation in vibration syndrome.

In order to clarify the role of cold on the cutaneous microcirculation in vibration syndrome, groups of rabbits vibrated at 4 degrees and room temperature served as the subjects of this study. A cold provocation test, capillary microscopy, and laser-Doppler flowmetry were used to evaluate the microcirculations of the test rabbits. The results indicated that vibration-induced impairment of the microcirculation was more prominent in the 4 degrees vibration group than in the room temperature group. The severities of the microcirculatory disturbances were dose-effect correlated. Vibration induced not only functional disturbances but also structural destruction of the capillaries. Furthermore cold temperatures enhanced these abnormalities of the blood vessels.

Animals↗
PubMed1991

Interactions of adenosine and vecuronium in neuromuscular blockade in cats.

The effect of adenosine on the neuromuscular blockade induced by vecuronium and the capacity of neostigmine to reverse this combined blockade were studied in 30 cats on a standard sciatic nerve--tibialis anterior muscle preparation. Adenosine infused to 6 cats at a constant rate (3.9 +/- 1.1 mg/kg/min) to produce a stable 50% reduction of the mean arterial pressure did not affect neuromuscular transmission. At the same 50% reduction of the mean arterial pressure by adenosine or sodium nitroprusside infusion in another 15 cats, adenosine (n = 9) significantly potentiated vecuronium-induced neuromuscular blockade, but sodium nitroprusside (n = 6) did not. Neostigmine antagonized the neuromuscular blockade of similar degrees produced either by the combination of adenosine with vecuronium in the above 9 cats or by vecuronium alone in the remaining 9 cats. There was no significant difference in the doses of neostigmine given. Because no potentiation was found at the same level of hypotension induced by sodium nitroprusside, the potentiation effect of adenosine on neuromuscular blockade is not likely to be due to the hypotensive effect of adenosine, but may be due to impairment, by adenosine, of acetylcholine release from motor nerve endings. We conclude that adenosine potentiates neuromuscular blockade by vecuronium and that neostigmine can be expected to reverse this combined blockade.

Adenosine↗
PubMed1991

Determination of vecuronium in blood by HPLC with UV and electrochemical detection: a pilot study in man.

Vecuronium bromide is a non-depolarizing neuromuscular blocking agent with a rather low therapeutic level. Rapid, sensitive, and selective determination of vecuronium bromide in human blood or plasma was essential for pharmacokinetic study. We developed such a method using HPLC with electrochemical detection. Samples were first acidified, followed by a one-step liquid-liquid extraction. Tubocurarine, which has a structure similar to that of vecuronium, was used as the internal standard. The electrochemical detector, Ag/AgCl electrodes, was operated by setting the working electrodes, W1 and W2, at +0.65 V and +1.05 V, respectively. When vecuronium blood concentration was plotted versus peak area ratios (PAR) of vecuronium over tubocurarine, a linear relationship was observed over the range of 25 ng/mL to 500 ng/mL with a correlation coefficient greater than 0.997. Clinically possible sources of interference, such as atropine, apresoline, droperidol, fentanyl, labetalol, thiopentone, atracurium, and valium, were examined and none showed interference in the assay of vecuronium and tubocurarine. This method has been successfully applied in a preliminary study of the pharmacokinetics of vecuronium in a patient undergoing surgery. The low detection limit of this method in the patient was 3 ng/mL.

Chromatography, High Pressure Liquid↗
PubMed1991

[Effect of succinylcholine on recovery of atracurium-induced neuromuscular blockade].

If muscle relaxation is inadequate at the end of surgery, a transient increase in neuromuscular (NM) blockade should be needed to facilitate closure. Succinylcholine is the only agent of short duration available currently and could be used in the just mentioned circumstance. Therefore, the study was designed to investigate the effects of succinylcholine on the recovery of atracurium-induced NM blockade. Sixty-four female patients who underwent elective surgery under general anesthesia were allocated into 6 groups. Before anesthesia, no patient had received drugs which affect NM transmission. In all patients anesthesia was induced with thiopental, diazepam and fentanyl and maintained with 50% nitrous oxide in oxygen and 0.5-1.5% isoflurane. During anesthesia, blood pressure and electrocardiogram were monitored and end-tidal CO2 was maintained at 30-40 mmHg. Control records of the integrated electromyography responded to train-of-four supramaximal stimulation using a Datex Relaxograph were obtained after induction of anesthesia before a block was produced with an initial dose of succinylcholine 1.0 mg in group I (n = 8) or atracurium 0.4 mg/kg in groups II-VI. On first twitch (T1) recovering to 50% of control, 0.4 mg/kg, 0.6 mg/kg, 0.8 mg/kg, 1.0 mg/kg and 1.2 mg/kg of succinylcholine were given in groups II (n = 11), III (n = 14), IV (n = 11), V (n = 10), VI (n = 10) respectively. It was seen that succinylcholine 0.4 mg/kg antagonized NM blockade by atracurium but at 0.6 mg/kg, 0.8 mg/kg, 1.0 mg/kg, 1.2 mg/kg it enhanced that.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effect of physostigmine on the loss of consciousness induced by midazolam, etomidate and althesin.

The effect of physostigmine, a cholinesterase inhibitor, on the loss of consciousness induced by three different intravenous induction anesthetics, namely midazolam, etomidate and althesin at ED50, was studied in three comparable groups of patients. Ten min before induction, the first and second groups received physostigmine 8 micrograms/kg and 16 micrograms/kg, respectively, and the third group received 2 ml of saline solution. Physostigmine 16 micrograms/kg resulted in a significant decrease in the percentage of unconscious patients with midazolam (from 50% to 10%), but it did not modify the incidence with etomidate or althesin. Physostigmine at doses of 8 micrograms/kg and 16 micrograms/kg could cause 6.7% and 10% nausea, respectively. Although the mechanism of the drug interaction of physostigmine and midazolam is unclear, physostigmine could be used clinically to reverse post-anesthetic somnolence induced by midazolam.

Adult↗
PubMed1991

[The study of cancer pain and its correlates].

From August 1989 to December 1990, we collected 1523 cases of malignancy at Tri-service General Hospital (TSGH), and 470 cases (30.9%) of these malignancy had pain complaint. Moreover, we found that 68.1% (79/116 cases) of malignancy with bony metastasis had pain complaint. These informations were obtained from medical records. By counting the site of these 1523 cases, the leading sites in sequence were lung (207 cases), stomach (164 cases), cervix uteri (132 cases), breast (117 cases) and colon (91 cases). Regarding the incidence of cancer pain among these malignancy, bone cancer had the highest incidence (75.0%), followed by tongue (66.7%), brain (65.7%), liver (62.3%) and pancreas (60.0%). There was no difference of the incidence of cancer pain between male and female. The incidences of cancer pain in different age groups were different; the young patients had higher incidence than elderly patients. The analgesics for cancer pain used most frequently by physicians at TSGH were nonsteroid anti-inflammatory drugs and meperidine. Although the therapeutic management of cancer pain has been advancedly developed, we found that the treatments of cancer pain by physicians at TSGH were not aggressive enough. Therefore, promotion of the concept in advanced pain control and techniques is our important task in the near future.

Adult↗
PubMed1991

[Rediffusion system and cuff pressure of Brandt's endotracheal tube].

During anesthesia increase of the endotracheal cuff pressure might be caused by anesthetic gases used, especially nitrous oxide (N2O), which easily diffuses into the cuff. In 1983, Brandt developed a blocking system which is called Rediffusion System. The principle of Rediffusion System is to make use of an enlarged pilot balloon to facilitate the removal of nitrous oxide which has diffused into the cuff during anesthesia. This study was designed to test and verify the function of Brandt tube's Rediffusion System during anesthesia using nitrous oxide as an anesthetic. Twenty four patients (age 19-82 yr; ASA physical status I-III) who underwent surgery under general anesthesia were allocated into three groups. For endotracheal intubation, in group I (n = 11) and group II (n = 5), Mallinckrodt Brandt tubes respective of internal diameter (ID) = 7 mm and ID = 8 mm were used, and in group III (n = 8) Portex Blue-line tubes with ID = 7 mm was used. Anesthesia was maintained with N2O, isoflurane, and oxygen and the FiN2O was kept around 50%. The cuff pressure was measured at the intervals of 30 min for 3 h. There were no significant differences of initial cuff volumes between group I and group II, but the initial cuff volumes of Portex blue-line tube were significantly larger than Brandt tubes at desired pressure level. Cuff pressures increased as the duration of anesthesia lengthened in all types of endotracheal tubes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗