Biomedical subjects

M Yamakage

Publications and source records attributed to M Yamakage.

64 records · Page 4Linked to original sources

PubMed1993

Inhibitory effects of four inhaled anesthetics on canine tracheal smooth muscle contraction and intracellular Ca2+ concentration.

To clarify the mechanisms by which inhaled anesthetics directly inhibit tracheal smooth muscle contraction, we investigated the effects of these anesthetics on muscle tension and intracellular Ca2+ concentration ([Ca2+]i). Tension was measured using an isometric transducer, and [Ca2+]i was measured using Fura-2, an indicator of [Ca2+]i. Addition of 1 microM carbachol increased muscle tension and [Ca2+]i. All inhaled anesthetics significantly decreased both muscle tension and [Ca2+]i in the following order of inhibitory potency: halothane >> isoflurane > enflurane >> sevoflurane. In the presence of 10 microM verapamil, carbachol moderately increased muscle tension, but induced a transient increase of [Ca2+]i followed by a substantial reduction. Inhaled anesthetics in the presence of both carbachol and verapamil significantly decreased muscle tension without decreasing [Ca2+]i. Potency for suppression of tension under these conditions, which appeared to be independent of [Ca2+]i, was in the order: halothane >> enflurane > or = isoflurane >> sevoflurane. The best correlation we found with a measured reduction of muscle tension independent of [Ca2+]i was with oil/gas partition coefficients (r = -0.88, P < 0.001). In conclusion, inhaled anesthetics inhibit tracheal smooth muscle contraction by at least two mechanisms: 1) reduction of [Ca2+]i and 2) suppression of contractility, independent of [Ca2+]i. The close correlation between the muscle inhibition independent of [Ca2+]i and the oil/gas partition coefficients suggests that one of the major sites of action of inhaled anesthetics is membrane phospholipids.

Anesthetics↗

PubMed1993

[Mechanisms of action of volatile anesthetics on smooth muscle].

The development of intracellular Ca2+ fluorescent indicators and specific enzymatic substances as well as the application of the patch-clamp method have made it possible to clarify the mechanisms of action of volatile anesthetics inhibit smooth muscle contraction in part by decreasing intracellular Ca2+ concentration ([Ca2+]i); this effect is mediated by blocking calcium channels, especially the L-type voltage-operated channel, and by raising the intracellular cyclic AMP and cyclic GMP levels. Volatile anesthetic-induced suppression of smooth muscle contraction is also attributable to mechanisms independent of [Ca2+]i, which involve the depression of Ca2+ sensitization mediated by C kinase.

Anesthesia, Inhalation↗

PubMed1993

[Changes in 3 different kinds of body temperature during CPR for DOA patients].

We monitored 3 different kinds of temperature (the tracheal, forehead deep and rectal) during CPR for 8 DOA patients. The forehead deep temperature rose slowly from room temperature, and gradually reached the tracheal temperature. The rectal temperature, except for 2 cases, almost immediately exhibited a temperature close to the tracheal temperature. In 2 exceptions, the rectal temperature exhibited a much lower value than the other temperature monitors. On the other hand, the tracheal temperature seemed to represent the core temperature in all cases during CPR. In conclusion, the tracheal temperature is useful for the monitoring of the patient's temperature during CPR because it represents the core temperature and endotracheal intubation is essential for CPR.

Adult↗

PubMed1993

[Cerebral blood flow velocity and electroencephalogram for the evaluation of intraoperative brain function during intrathoracic hyperthermia].

It is well known that progressive hyperthermia exerts fatal damage on the human body. However, there have been few reports on the brain function or the means to provide adequate monitoring during hyperthermia. The purpose of this study was to introduce two new devices, the Life Scan electroencephalogram (EEG) Monitor (Neurometrics) and the TC2-64 (EME) transcranial Doppler sonography (TCD), both for monitoring brain function during hyperthermia. The Life Scan uses aperiodic analysis, which maps each waveform in relation to its frequency, amplitude, and time of occurrence rather than averaging a large number of waveforms over a given period. The Life Scan shows 80% of the whole amplitude of each wave as the activity edge (AE). The flow velocity of the middle cerebral artery was measured by TCD during hyperthermia. After the induction of modified neuroleptanesthesia (fentanyl and midazolam), AE was maintained at 11 Hz. With an increase in body temperature, AE gradually showed a trend toward a slow wave, though the slowing of EEG was interrupted when the patient awoke to slight stimulation. Therefore, it is speculated that the slowing of EEG in this case was caused by fentanyl. The mean cerebral blood flow velocity increased slightly from 28 to 32 cm.sec-1 by hyperthermia. It is concluded that the adoption of EEG and TCD was useful in determining the intraoperative cerebral function during hyperthermia.

Brain↗

PubMed1992

Direct inhibitory mechanisms of halothane on canine tracheal smooth muscle contraction.

Halothane directly relaxes airway smooth muscle. To determine the direct inhibitory mechanisms of halothane on canine tracheal smooth muscle contraction, the effects of this anesthetic on the levels of several intracellular second messengers were investigated by measuring intracellular Ca2+ concentration ([Ca2+]i), Ca2+/phospholipid-dependent protein kinase (PKC) translocation, and intracellular cyclic adenosine monophosphate concentration ([cAMP]i). When carbachol (1 microM) was used to increase [Ca2+]i to the same concentration as that induced by high-K+ (72.7 mM), the carbachol-induced contraction was more than twice as great, indicating that carbachol enhances the sensitivity of contractile elements to Ca2+ or activates a Ca(2+)-independent mechanism. Similarly, 12-deoxyphorbol 13-isobutylate, a potent PKC activator, markedly potentiated high-K(+)-induced muscle contraction without an increase of [Ca2+]i. The addition of halothane (0.33, 0.75, 1.15, and 1.47 mM) decreased [Ca2+]i and the muscle tension induced by carbachol. However, the decrease of muscle tension was more marked than that of [Ca2+]i at the higher concentrations. Although [Ca2+]i in the presence of verapamil and carbachol was not affected by halothane, the anesthetic markedly decreased muscle force by decreasing the "Ca2+ sensitization" or the Ca(2+)-independent enhancement of tension observed with carbachol. Halothane (0.75 and 1.47 mM) significantly released the membrane-associated PKC to cytosol, which decreased PKC activity. [cAMP]i of the smooth muscle stimulated by carbachol was moderately but significantly increased by halothane. However, when equivalent relaxation was induced with forskolin, which acts via adenylate cyclase activation, a much higher [cAMP]i was observed, which suggests that halothane acts via an additional pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Changes in ventilatory pattern and arterial oxygen saturation during spinal anaesthesia in man.

Using a respiratory inductive plethysmograph and a pulse oximeter, we investigated the changes in the respiratory pattern and peripheral oxygen saturation (SpO2) of the finger before and during spinal anaesthesia in 20 surgical patients. The rib cage contribution to the tidal volume (%RC) increased significantly from before (20.4 +/- 4.3%) to during spinal anaesthesia (30.4 +/- 4.8%). However, in those patients who fell asleep 60 min after subarachnoid injection of a local anaesthetic, %RC returned to the preanaesthetic value (23.0 +/- 5.9%). Finger SpO2 increased significantly during spinal anaesthesia, but the femoral arterial oxygen saturation did not change. The authors conclude that spinal anaesthesia increases %RC in conscious patients. However, the increment of %RC does not cause a major change in arterial oxygen saturation.

Adult↗

PubMed1992

[Two cases of diffuse pulmonary lymphangiomyomatosis].

We cared 2 patients with diffuse pulmonary lymphangiomyomatosis (LAM) through the perioperative period. LAM is a disease of uncertain origin and poor prognosis because of respiratory failure. Therefore, it is important to provide not only a good anesthetic care but also a good preoperative respiratory care. In the first case (a 35-yr-old woman), an open lung biopsy was performed after dyspnea and sputum had disappeared with preoperative medications of a bronchodilator and some antibiotics. In the second case (a 35-yr-old woman), oophorectomy was performed after FEV1.0% had remarkably increased with preoperative medication of a bronchodilator. Both patients did well through the perioperative period without any trouble or complications, such as pneumonia or severe hypoxemia, presumably owing to our perioperative management system.

Adult↗

PubMed1991

[A case report of monitoring neuromuscular blockade during anesthesia in a patient with facioscapulohumeral muscle dystrophy].

Facioscapulohumeral muscle dystrophy (FSHMD) is characterized by slowly progressive wasting of facial, pectoral and shoulder-girdle muscles that begins in adolescence. A 31 year-old man with FSHMD had dystrophic changes in the deltoid, anterior serratus and pectoralis major muscles but not in the distal muscle of his arms and legs. He underwent an operation for thoraco-scapula fixation under enflurane-nitrous oxide anesthesia with vecuronium 6 mg. At the end of the surgical procedure, the train-of-four (TOF) responses of a thumb and a toe, as measured by using an acceleration transducer, were recorded simultaneously. TOF stimulation in an arm demonstrated an apparent fade phenomenon (TOF; 0.54), while a TOF test in the leg showed complete recovery of the TOF ratio (TOF; 1.0). The patient revealed no clinical signs of residual neuromuscular blockade. It was clear that there was a difference in the degree of neuromuscular block between the arm and the leg in a FSHMD patient. Use of the peripheral nerve stimulator only in the arm may be an unreliable guide to assess neuromuscular block in FSHMD patients. Therefore, two sites should be chosen for monitoring neuromuscular blockade in a FSHMD patient.

Adult↗

PubMed1991

[Utility of Bullard intubating laryngoscope with a special stylet in two cases of difficult tracheal intubation].

The Bullard intubating laryngoscope is useful for cases of difficult tracheal intubation, but a skilled hand is needed to manipulate it. In two cases of difficult tracheal intubation, we used a recently improved Bullard intubating laryngoscope to which a special stylet is attached to introduce an endotracheal tube easily into the larynx. The difficulties of tracheal intubation were caused by micrognathia and trismus in one case and by restriction of neck movement and trismus due to ankylosing spondylitis in the other case. Using the Bullard intubating laryngoscope with the special stylet, intubation was done smoothly in both cases. This improved Bullard intubating laryngoscope is recommended for cases of difficult tracheal intubation.

Adolescent↗

PubMed1990

[The evaluation of tracheal temperature to monitor core temperature in various operations].

Tracheal temperature was evaluated to monitor core temperature during cardiac, upper abdominal and lower abdominal operations. The tracheal temperature was measured by a thermistor attached to the intra-cuff of the tracheal tube. In cardiac surgery, there was a good correlation between tracheal temperature and forehead deep temperature (r = 0.93) before and after cardiopulmonary bypass, and also between tracheal temperature and the temperature of blood from the cardiopulmonary bypass (r = 1.00) during cardiopulmonary bypass. These results indicate that tracheal temperature accurately reflects carotid artery temperature. In upper abdominal operations, the tracheal temperature showed good correlations with forehead core, esophageal, bladder and rectal temperatures (r = 0.81-0.90). On the other hand, bladder and rectal temperatures were different from forehead deep (r = 0.43, 0.55) and tracheal temperatures in lower abdominal operations. These results suggest that the tracheal temperature is valuable to monitor core temperature.

Abdomen↗