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Biomedical subjects

K Amaha

Publications and source records attributed to K Amaha.

At least 73 records · Page 4Linked to original sources
PubMed1994

Middle cerebral arterial blood flow velocity increases during laparoscopic cholecystectomy.

The effects of intraperitoneal CO2 insufflation on middle cerebral arterial blood flow velocity were evaluated in 10 patients undergoing laparoscopic cholecystectomy under general anesthesia with nitrous oxide, oxygen, and isoflurane. Blood flow velocity was measured using transcranial Doppler ultrasonography. During CO2 insufflation, Paco2 and the end-tidal CO2 concentration (PETCO2) increased significantly compared with the preinsufflation baseline value (P < 0.01) while ventilation was kept constant. Cerebral blood flow velocity also increased significantly in comparison with the baseline value (P < 0.01). These values still exceeded baseline values 10 min after deflation of the peritoneal cavity. A significant positive correlation was observed between blood flow velocity and Paco2 (P < 0.001). Our results suggest that intraperitoneal CO2 insufflation during laparoscopic cholecystectomy increases cerebral blood flow and that this is probably due to an increased Paco2.

Adult↗
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↗
PubMed1994

[Response to a questionnaire on DNR-order from 307 trustee members of Japanese Medical Societies].

A questionnaire on the use of DNR-order was conducted on 427 trustee members of Japan Society of Reanimatology, Intensive Care Medicine and Anesthesiology with responses from 307 or 71.9%. The results of the questionnaire are as follows: DNR-order is unnecessary, 2.9%. Necessary depending on the situation, 96.7%. Here dying in dignity was the main reason for necessity of DNR-order and ethical, legal and technical problems were the reasons cited for objection. Patients' will is indispensable for DNR-order, 11.4%. Patients' will is not indispensable, 84.9%. Quality and quantity of treatment after the decision of DNR-order should not be limited or withdrawn, 21.2%. Should be withdrawn except for respirator, 60.6%. The percentage of those who had carried out a DNR-order was 69.1% (most of them more than once), but half of them did not describe the order on the chart. A guideline for a DNR-order by scientific societies and/or governmental policy for a DNR-order should be made and publicized not only for the benefit of the patients and their families but also for physicians themselves.

Adult↗
PubMed1993

Contractility of fatigued diaphragm is improved by dobutamine.

The effects of dobutamine (DOB) on diaphragmatic fatigue were examined in 20 anaesthetized, mechanically ventilated dogs. Animals were divided into two groups: the DOB group (n = 10) and the control group (n = 10). Diaphragmatic fatigue was induced by intermittent supramaximal electric stimulation applied to bilateral phrenic nerves at a frequency of 20 Hz for 30 min. Diaphragmatic contractility was assessed with transdiaphragmatic pressure (Pdi). After diaphragmatic fatigue, Pdi decreased at low-frequency (20 Hz) stimulation (P < 0.05), whereas the decrease was minimal at high-frequency (100 Hz) stimulation. In the DOB group, after producing fatigue, the continuous administration of 10 micrograms.kg-1.min-1 dobutamine iv for 30 min produced an increased Pdi at both frequencies of stimulation (P < 0.05). The Pdi returned to pre-fatigue values after cessation of dobutamine administration. In the control group, the speed of recovery from fatigue was much slower at low-frequency stimulation. The integrated diaphragmatic electric activity (Edi) in the two groups did not change throughout the experiment at any frequency of stimulation. We conclude that dobutamine improves contractility in fatigued diaphragm.

Animals↗
PubMed1993

Recoveries of post-tetanic twitch and train-of-four responses after administration of vecuronium with different inhalation anaesthetics and neuroleptanaesthesia.

We have studied recovery of post-tetanic twitch (PTT) and train-of-four (TOF) responses after administration of vecuronium in 100 patients under different inhalation anaesthetics and neuroleptanaesthesia. Patients were allocated randomly to five groups of 20 patients each to receive: neuroleptanaesthesia (droperidol and fentanyl), halothane, isoflurane, enflurane or sevoflurane (1 MAC in nitrous oxide and oxygen). The times from initial administration of vecuronium 0.2 mg kg-1 to the first appearances of T1, T2, T3 and T4 differed significantly between groups. However, the intervals to the first appearance of PTT1, PTT10 and PTT20 did not differ significantly between groups.

Adult↗
PubMed1993

Relationship between post-tetanic twitch and single twitch response after administration of vecuronium.

We have studied the relationship between post-tetanic twitch (PTT) and single twitch response after administration of vecuronium 0.2 mg kg-1 in 100 patients during neuroleptanaesthesia (NLA) (droperidol and fentanyl) and during anaesthesia with halothane, isoflurane, enflurane or sevoflurane (1 MAC in nitrous oxide and oxygen). Intervals from PTT1 to single twitch, and post-tetanic-count (PTC) (number of PTT responses) at the onset of single twitch were determined electromyographically. These intervals in the isoflurane, enflurane and sevoflurane groups differed from those in NLA and halothane groups. PTC in the isoflurane, enflurane and sevoflurane groups differed from those in the NLA group, and PTC in the sevoflurane group significantly from those in the NLA and halothane groups. These results are consistent with the view that PTT reflects prejunctional block, whilst the single twitch response is indicative of postjunctional block.

Adult↗
PubMed1993

Circulating endothelin-1 concentrations in acute respiratory failure.

To elucidate the pathophysiologic role of endogenous endothelin (ET)-1 in acute respiratory failure, we measured plasma immunoreactive ET-1 levels in 13 patients with acute respiratory failure, and compared those with hemodynamic and respiratory parameters. The mean plasma ET-1 levels (10.7 +/- 5.0 pg/ml) in 13 patients with acute respiratory failure at the time of hospital admission were about sevenfold greater than those of healthy subjects (1.5 +/- 0.5 pg/ml, n = 16). Plasma ET-1 levels positively correlated with right atrial pressure (r = 0.626), systolic pulmonary arterial pressure (r = 0.726), mean pulmonary arterial pressure (r = 0.591), and the resistance ratio (pulmonary vascular resistance/systemic vascular resistance) (r = 0.658). They also showed correlations with peak airway pressure (r = 0.588), mean airway pressure (r = 0.607), and airway resistance (r = 0.756). Stepwise multiple regression analysis confirmed the significance of these observations. Our data suggest that raised circulating ET-1 levels may partly contribute to the development of pulmonary vasoconstriction and bronchoconstriction associated with acute respiratory failure.

Acute Disease↗
PubMed1993

[Anesthetic management of a patient with a history of right upper lobectomy for esophageal resection via left thoracotomy].

We anesthetized a patient for esophageal resection in a right lateral decubitus position, because of his right pleural adhesion after lobectomy for tuberculosis. Although hypoxemia was expected on left lung compression during the surgery, oxygenation was not compromised. A good ventilation/perfusion relationship might have been maintained in both the right and left lungs during the procedure.

Anesthesia, Epidural↗
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 cardiac output.

The effects of cardiac output (Qt) on diaphragmatic blood flow (Qdi) and diaphragmatic fatigue and its recovery were studied in dogs. Qdi was estimated by measurement of the left inferior phrenic arterial blood flow (QdiL). There was a significant positive correlation between % Qt and % QdiL. Transdiaphragmatic pressure (Pdi) was significantly smaller in the lowered Qt group than the control at the end of fatigue, and the speed of recovery from the fatigue was also significantly slower in the lowered Qt group. It is concluded that Qt was considered to play an important role in the pathogenesis of diaphragmatic fatigue and its recovery in the mechanically ventilated dogs.

Journal Article↗
PubMed1991

A close relationship between post-tetanic twitch and train-of-four responses during neuromuscular blockade by vecuronium.

The relationship between post-tetanic twitch (PTT) and train-of-four (TOF) responses after intravenous administration of vecuronium were studied using EMG in 20 patients under nitrous oxide and enflurane anesthesia. After the initial dose (0.2 mg.kg(-1)) of vecuronium, the detectable first twitch of PTT (PTT(1)) always preceded that of TOF (TOF(1)) with the mean time interval of 10.7 +/- 2.6 min. The post-tetanic count (PTC) which coincided with the first appearance of TOF(1) was 9.4 +/- 2.6. After the appearance of TOF(1), the magnitude of TOF(1) was almost identical to that of PTC(10) until full recovery from neuromuscular blockade was observed, whether the supplemental doses of vecuronium (0.03-0.04 mg.kg(-1) i.v.) were administered or not. The magnitude of TOF(2) was slightly lower than that of PTC(20). These results suggest that there is a close relationship between these two types of response, and by evaluating not only PTC but also the magnitude of each PTT, the recovery of TOF responses can be predicted and its extent be estimated fairly accurately.

Journal Article↗