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Biomedical subjects

K Amaha

Publications and source records attributed to K Amaha.

At least 19 recordsLinked to original sources
PubMed1995

Amrinone improves contractility of fatigued diaphragm in dogs.

The effects of amrinone, a bipyridine derivative, on diaphragmatic contractility and fatigue were examined in 36 anaesthetized, mechanically ventilated dogs divided into four groups. In Group Ia (n = 8), dogs without diaphragmatic fatigue were given a bolus injection (0.75 mg.kg-1) followed by continuous infusion (10 micrograms.kg-1.min-1) of amrinone iv. In Group Ib (n = 8), animals without fatigue received infusion only of maintenance fluid. In Group IIa (n = 10) and Group IIb (n = 10), diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20 Hz applied for 30 min. After producing fatigue, amrinone (0.75 mg.kg-1 loading dose plus 10 micrograms.kg-1.min-1 maintenance dose) iv were administered in Group IIa. Only maintenance fluids were administered in Group IIb during this period. Diaphragmatic contractility was assessed in each group by measuring transdiaphragmatic pressure (Pdi). Compared with Group Ib, Pdi at any stimuli in Group Ia did not differ. After producing fatigue, in Group IIa and Group IIb, Pdi decreased at low-frequency (10-30 Hz) stimulation (P < 0.05), whereas no change in Pdi was observed at high-frequency (50-100 Hz) stimulation. In Group IIa, Pdi to each stimulus increased during amrinone infusion compared with Group IIb (p < 0.05). In Group IIb, the speed of recovery from fatigue was relatively slower at low-frequency stimulation. The integrated diaphragmatic electric activity (Edi) did not change throughout the experiment. These results indicate that amrinone improves contractility in the fatigued diaphragm.

Amrinone↗
PubMed1995

Post-tetanic burst: a new monitoring method for intense neuromuscular block.

A new stimulation pattern for evaluation of intense neuromuscular block (post-tetanic burst (PTB)) was compared with post-tetanic twitch (PTT) during spontaneous recovery from vecuronium-induced neuromuscular block. Thirty adult patients were allocated to two equal groups and we measured times from administration of vecuronium 0.1 mg kg-1 to return of PTB and PTT responses, and evoked responses to PTB and PTT stimuli. For PTB stimulation, a 50-Hz tetanus was applied at 50 mA for 5 s, and after a pause of 3 s, a 50-Hz burst stimulation was applied, consisting of three impulses at 50 mA. PTB stimuli were delivered every 5 min. Similarly, PTT consisted of a tetanus, a 3-s pause and one single twitch stimulation repeated every 5 min. Time to return of the PTB response was significantly shorter than that of PTT (mean 23.7 (SD 7.9) compared with 30.7 (7.0) min) (P = 0.0160), although evoked responses to PTB did not differ significantly from those of PTT throughout recovery from vecuronium-induced neuromuscular block. This study suggested that PTB was more sensitive in evaluating intense neuromuscular block than PTT.

Adult↗
PubMed1995

Effects of nitric oxide synthase inhibitor on hemodynamic change and O2 delivery in septic dogs.

To elucidate the role of nitric oxide (NO) in septic shock, we measured hemodynamic and pulmonary gas changes in anesthetized dogs after intravenous administration of bacterial lipopolysaccharide (LPS) with or without NO synthase inhibitor, NG-nitro-L-arginine (L-NNA). Infusion of LPS (250 ng.kg-1.min-1) for 2 h decreased mean arterial pressure over 1-4 h. Although L-NNA (10 mg/kg) blocked LPS-induced hypotension, it decreased cardiac index, oxygen delivery index, arterial pH, and arterial PO2 and increased systemic vascular resistance index in the presence or absence of LPS. Administration of NG-nitro-D-arginine (D-NNA, 10 mg/kg) alone caused fewer hemodynamic effects (increased systemic vascular resistance index and decreased cardiac index) than L-NNA alone. Our study provides evidence that L-NNA prevents endotoxin-induced hypotension but decreases cardiac output and oxygen delivery, effects that may, in part, be due to a nonspecific NO synthase-independent event. Thus clinical use of NO synthase inhibitors for the treatment of septic shock should be cautiously considered.

Amino Acid Oxidoreductases↗
PubMed1994

Usefulness of central venous oxygen saturation monitoring during cardiopulmonary resuscitation. A comparative case study with end-tidal carbon dioxide monitoring.

The usefulness of continuous monitoring of central venous oxygen saturation (ScvO2) in comparison with the capnogram during cardiopulmonary resuscitation (CPR) was demonstrated in a cardiac arrest patient. ScvO2 and end-tidal carbon dioxide (ETCO2) decreased following cessation of chest compression or increased during recovery of systemic circulation. During the complete stasis of systemic circulation, when defibrillation was done, ScvO2 did not change, while ETCO2 gradually decreased. However the larger decrease in ScvO2 temporally occurred when chest compression was resumed. And also the ScvO2 monitoring had great advantage to detecting peripheral tissue oxygenation. ScvO2 seems to be no less accurate and reliable monitoring than the capnogram during CPR procedures. Since the capnogram is non-invasively and easily used in cardiac arrest patients, ScvO2 monitoring combined with the capnogram is a more preferable method for assessing the efficacy of ongoing CPR.

Blood Gas Analysis↗
PubMed1994

Cutaneous iontophoretic application of condensed lidocaine.

The purpose of this study was to determine whether iontophoretic application of high concentrations of lidocaine, with the same current, would produce cutaneous local anaesthesia rapidly enough for clinical practice. Twenty healthy volunteers, 17 male and three female, were selected for study. After five-minute or ten-minute iontophoresis using lidocaine 4, 10, 20, 30, 50%, we assessed the response to pin prick with a 27-gauge sterile needle inserted to the depth of 2 mm at five random locations in the iontophoretically-stimulated area. Also, plasma lidocaine concentrations were measured in the venous blood samples which had been taken from three male subjects, at 3, 10, and 30 min after iontophoresis with lidocaine 50%. The pain score after five-minute iontophoresis was higher than that after ten-minute iontophoresis, using each concentration of lidocaine (P < 0.001), whereas the pain scores had no correlation with lidocaine concentration within five-minute and ten-minute iontophoresis groups, respectively (P: NS). On the other hand, plasma lidocaine concentration was < 1.0 micrograms.ml-1 in all samples. No side effects other than erythema were observed after iontophoresis using high concentrations of lidocaine up to 50%. These results showed that by increasing the lidocaine concentration of the applied solution up to 50%, the application time of iontophoresis cannot be reduced from ten to five minutes without losing analgesic effect, although iontophoresis itself can be performed with safety.

Administration, Cutaneous↗
PubMed1994

Post-tetanic count and single twitch height at the onset of reflex movement after administration of vecuronium under different types of anaesthesia.

We have studied post-tetanic count (PTC) and single twitch height at the onset of reflex movement to carinal stimulation after administration of vecuronium with five different types of anaesthesia. Seventy-five adult patients were allocated randomly to five groups of 15 patients each, to receive one of the following anaesthetics: neuroleptanaesthesia (fentanyl and droperidol) or 1 MAC of either halothane, isoflurane, enflurane or sevoflurane with 66% nitrous oxide in oxygen. During spontaneous recovery from vecuronium-induced neuromuscular block, the carina was stimulated with a suction catheter every 150 s. Single twitch heights at the onset of reflex movement were similar (2.0-2.7% of control values) between the five groups. In contrast, PTC at the onset of reflex movement to carinal stimulation differed (7.4-17.0) between groups.

Adult↗
PubMed1994

Effect of tetanic stimulation on subsequent train-of-four responses at various levels of vecuronium-induced neuromuscular block.

Tetanic stimulation influences subsequent neuromuscular responses. In addition, the tetanus-induced changes in neuromuscular responses differ according to the level of neuromuscular block at which tetanic stimulation is delivered. We studied the tetanus-induced effect on subsequent train-of-four (TOF) responses at various levels of vecuronium-induced neuromuscular block in 45 anaesthetized patients. Tetanic stimulation was applied when a twitch height of T1 returned to 25%, 50% and 75% of its control twitch height (T0) (groups 1, 2 and 3, respectively) after administration of vecuronium 0.1 mg kg-1. Maximum post-tetanic percentage increases in TOF responses in groups 1, 2 and 3 were 257 (SD 119)%, 107 (75)% and 68 (54)% for T1/T0 (P < 0.001 for group 1 vs 2; P < 0.001 for group 1 vs 3) and 535 (259)%, 421 (213)% and 292 (171)% for T4/T1 (P < 0.01 for group 1 vs 3), respectively. Durations of post-tetanic increases in TOF responses in groups 1, 2, and 3 were 52 (19) s, 37 (14) s and 32 (13) s for T1/T0 (P < 0.05 for group 1 vs 2; P < 0.01 for group 1 vs 3) and 53 (17) s, 46 (15) s and 35 (12) s for T4/T1 (P < 0.05 for group 1 vs 3), respectively. These data suggest that the tetanus-induced effect on subsequent TOF is more apparent and lasts longer at greater degrees than at lesser degrees of neuromuscular block.

Adult↗
PubMed1994

Effects of TNF-alpha on hemodynamic changes and circulating endothelium-derived vasoactive factors in dogs.

To elucidate the relation of tumor necrosis factor-alpha (TNF-alpha)-induced hemodynamic change to endothelium-derived vasoactive factors, we simultaneously measured hemodynamic parameters and circulating endothelin (ET)-1, ET-3, nitrite/nitrate (NOx), and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) in anesthetized dogs following administration of TNF-alpha with or without NG-nitro-L-arginine (L-NNA), a nitric oxide (NO) synthase inhibitor, and indomethacin, a cyclooxygenase inhibitor. Natural human TNF-alpha (10 micrograms/kg, n = 5) with or without L-NNA (1 mg/kg, n = 5) or indomethacin (2 mg/kg, n = 5) was administered intravenously as a bolus, while administration of vehicle served as control (n = 5). After administration of TNF-alpha, mean arterial pressure and cardiac index significantly decreased, whereas systemic (SVRI) and pulmonary (PVRI) vascular resistance index increased. Plasma levels of ET-1, ET-3, NOx, and 6-keto-PGF1 alpha significantly (P < 0.01) increased at 1 h. L-NNA or indomethacin blocked TNF-alpha-induced hypotension and remarkably increased SVRI but did not affect decreased cardiac index. Our data suggest that endogenous ET-1 may partly contribute to TNF-alpha-induced increases in SVRI and PVRI, against which ET-3, NO, and prostacyclin may function as compensatory vasodilators.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

[Effects of pressure support ventilation (PSV) or PSV+PEEP on the respiratory function during general anesthesia under spontaneous ventilation].

This study was performed to examine the hypothesis that PSV with PEEP compared to spontaneous breathing with a circle anesthesia system may have beneficial effects on gas exchange and work of breathing during inhalational anesthesia. Nine patients (age; 58 +/- 20 yr) scheduled to receive general anesthesia for orthopedic (n = 3) or ENT (n = 6) surgery were randomly assigned in a triple cross-over manner to breathe with a standard anesthesia circle system, 5 cmH2O PSV, and 5 cm H2O PSV above 5 cmH2O PEEP. General anesthesia was induced with thiamylal (5 mg.kg-1) and succinylcholine (1 mg.kg-1), followed by tracheal intubation. General inhalation anesthesia was maintained with 1% isoflurane and nitrous oxide in 40% oxygen. Patients were permitted to breathe spontaneously. A BiPAP-S Ventilatory Support System was connected to a standard anesthesia machine instead of a reservoir bag to deliver PSV or PSV with PEEP. Respiratory parameters were measured with a C-P 100 Pulmonary Monitor. After breathing for 20 minutes with the assigned mode, measurements and blood gas sampling were performed. Statistical analysis was performed with ANOVA. There were no statistical differences in PaO2 within the three groups (table). PaCO2 was lower during PSV+PEEP, but the difference was not significant. This level of PSV or PSV with PEEP may have little beneficial effects on gas exchange in our study condition. The mean WOBp was smaller in the PSV with PEEP group but the difference was not statistically significant.

Adult↗
PubMed1992

Sternocleidomastoid muscle contractility at different levels of isoflurane anaesthesia in humans.

We have measured force-frequency curves of the sternocleidomastoid muscle in six patients at three different levels of isoflurane anaesthesia (1.0, 1.4 and 1.8 MAC). Spontaneous ventilation was suppressed by mild hypocapnia induced by mechanical ventilation. An anterior force vector of the sternocleidomastoid muscle was measured during isometric contraction induced by supramaximal electrical stimulation at 20, 50 and 100 Hz to the i.m. accessory nerves of the muscle. The force response at 20 Hz and 50 Hz did not change with an increase in isoflurane concentration, but it decreased at 100 Hz as isoflurane concentration increased. The reduction in the force at 100 Hz may be caused mainly by impaired neuromuscular transmission.

Adolescent↗
PubMed1992

Plasma alpha-human atrial natriuretic peptide concentration in patients with acute lung injury.

To elucidate the pathophysiologic role of alpha-human atrial natriuretic peptide (alpha-hANP) in acute lung injury, plasma alpha-hANP concentrations were measured in 15 patients with severe lung injury, and the relationships of plasma alpha-hANP levels to the severity of lung injury, diuresis/natriuresis, and fluid balance were examined. The mean concentrations of plasma alpha-hANP (188.0 +/- 94.6 pg/ml) in patients with severe lung injury at the entry into the study were significantly (p less than 0.001) higher than those in normal subjects (31.7 +/- 12.0 pg/ml). Plasma alpha-hANP levels decreased in parallel with the improvement of lung injury in nine of 15 patients, whereas they changed little, if any, in the patients who did not recover. Plasma alpha-hANP concentrations correlated positively with urine volume, urinary sodium excretion, and excreted fraction of filtered sodium, but they correlated negatively with fluid balance at the onset of the disease as well as during the clinical course. It is suggested that elevation of circulatory alpha-hANP may reflect an adaptative mechanism to remove excessive fluid retention and reduce pulmonary hypertension for acute lung injury.

Acute Disease↗
PubMed1992

[Anesthetic management of a patient with right ventricular myxoma].

Right ventricular myxoma in a 79 year old male, whose pulmonary trunk was obstructed by the myxoma, was reported. Myxoma of the heart is rare, and especially right ventricular myxoma is rare. Myxomas of the heart have been reported by thirty-seven authors, but right ventricular myxoma has been reported by only one author. Anesthesia for the removal of right ventricular myxoma must be carried out carefully, because some critical troubles may happen during anesthesia for the resection of the right ventricular myxoma. Particularly, occlusion of the pulmonary artery is the most dangerous complication.

Aged↗
PubMed1991

Haemodynamic changes during the apnoea test for diagnosis of brain death.

Haemodynamic responses to the apnoea test for the diagnosis of brain death were investigated in nine patients with severe head injury or cerebrovascular disease. To prove apnoea, the ventilator was disconnected for ten minutes and oxygen was insufflated to avoid hypoxaemia. No respiratory movement was seen in any patient. Ten minutes after disconnecting the ventilator, PaCO2 was increased to 78 +/- 3 mmHg and pH was reduced to 7.17 +/- 0.02. Adequate oxygenation was maintained in all patients. Cardiac output increased from 4.8 +/- 0.7 to 5.7 +/- 0.8 L.min-1 (P less than 0.05), and mean pulmonary artery pressure increased from 11 +/- 1 to 17 +/- 2 mmHg (P less than 0.01). However, mean arterial pressure, heart rate, pulmonary artery wedge pressure and right atrial pressure did not change. Plasma catecholamines were measured in three patients. Plasma norepinephrine concentrations increased in all three patients but the changes in plasma epinephrine were minimal. These circulatory responses to acute hypercapnia were less than those reported in awake volunteers and in patients during general anaesthesia. However, since plasma norepinephrine concentration increased during the test, some sympathoadrenal response, probably of spinal origin, was present, and may have prevented the direct depressant circulatory effects of acute hypercapnia. In conclusion, the apnoea test did not produce haemodynamic disturbances when respiratory acidosis was limited to a pH 7.17 +/- 0.02 and PaCO2 60-80 mmHg.

Adult↗
PubMed1991

Anaesthesia for Treacher Collins syndrome using a laryngeal mask airway.

Patients with Treacher Collins syndrome pose a serious problem to anaesthetists in maintaining their airway because of retrognathia. Two patients with Treacher Collins syndrome undergoing tympanoplasty are reported in whom a laryngeal mask was used in place of an endotracheal tube for airway maintenance.

Anesthesia, Inhalation↗
PubMed1991

[Diaphragmatic fatigue and its recovery are influenced by markedly decreased cardiac output: possible involvement of neuromuscular junction].

Effects of highly decreased cardiac output on the development and recovery of diaphragmatic fatigue were studied in dogs. The fatigue was induced by supramaximal electrical stimulation (20 Hz) of phrenic nerves for 30 minutes. Cardiac output was reduced during this period to 30% of control value by mechanically obstructing inferior vena cava with a balloon in animals with lowered cardiac output group (lowered Qt group). Cardiac output was maintained at normal value throughout the experiment in animals of the other group (control group). The animals were observed for recovery for 60 minutes after induction of the fatigue. The standardized transdiaphragmatic pressure (Pdi/Pdi 100) and integrated electromyographic activity (Edi/Edi 100) elicited by electrical test stimuli (20, 100 Hz) were significantly lower in lowered Qt group (P less than 0.01) during entire fatigue and recovery period. The decrease of Pdi/Pdi 100 and Edi/Edi 100 at high frequency test stimuli (100 Hz) was observed only in lowered Qt group. These results suggest that when cardiac output is severely decreased the diaphragm is more susceptible to fatigue, and that this may be caused by a failure of neuromuscular junction as well as by an impaired excitation-contraction coupling.

Animals↗
PubMed1990

Serum diatrizoate level during intraoperative cholangiography in patients without choledochal obstructions.

To assess the degree of regurgitation of contrast media during intraoperative cholangiography, serum diatrizoate levels were measured in 15 patients without demonstrable bile duct obstructions. The maximum pressure achieved during the injection was measured in seven cases and ranged from 13 to 39 cm H2O (average 21.7 +/- 9.3 cm H2O). Only two of the 15 patients studied had detected serum diatrizoate (in one patient 7-14 micrograms I/ml and the other patient 119-200 micrograms I/ml) after completion of the injection. The data suggest that regurgitation of contrast media into the blood during intraoperative cholangiography does not depend solely on injection pressure. Moreover the data suggest that in order to prevent adverse reactions to accidental intravenous contrast administration nonionic contrast media should be used in most, if not all, radiographic studies as some contrast media reaches the bloodstream.

Cholangiography↗