Mamoru Takiguchi

Relationship between aortic-to-radial arterial pressure gradient after cardiopulmonary bypass and changes in arterial elasticity.

Background An aortic-to-radial arterial pressure gradient may develop during and after cardiopulmonary bypass (CPB). The mechanisms of this pressure gradient remain controversial. To clarify the cause of the pressure gradient after CPB, the authors investigated the relationship between the pressure gradient and changes in the pulse wave velocity (PWV) before and after CPB. Methods The pressure gradient from the aorta to the radial artery and a change in PWV were measured with a wire (0.37 mm in diameter) tipped with a miniature pressure transducer in 12 patients undergoing cardiac surgery. The pressure distributions and waveforms were measured and recorded with electrocardiograph. The PWV was calculated by measuring the propagation time between the R wave of the electrocardiograph and the rising point of the arterial pressure waveform at 10-cm intervals. Results After CPB, 7 of 12 patients demonstrated a marked pressure gradient. In these patients, the pressure distribution showed a gradual decrease toward the periphery without a precipitous step-down in pressure at any one specific anatomic location. The PWV decreased as the intraarterial pressure decreased from the aorta to the radial artery, and the relative arterial elasticity decreased linearly toward the periphery. Conclusions The results showed that the decrease in PWV implies a decrease in arterial elasticity, and the decrease in the arterial elasticity correlated with the decrease in intraarterial pressure. These findings demonstrated that a radial artery pressure lower than the aortic pressure after CPB may be due to the decrease in arterial elasticity.

A case of tracheomalacia during isoflurane anesthesia

T racheomalacia is a rare disease. Congenital tracheomalacia manifests itself in infancy and may not resolve as the child grows. Acquired tracheomalacia has been reported sporadically, resulting from trauma (including tracheostomy), tumor, infection, inhalation of chronic irritants, and others (l-5). We present a case of tracheomalacia in a female patient with no respiratory problem. She had difficulty in the expiratory phase of spontaneous respiration during general anesthesia because of an extreme narrowing of the tracheal lumen on each expiration that was confirmed by bronchoscopic study.

The efficiency of beta 2-agonist delivery through tracheal tubes with the metered-dose inhaler: an in vitro study.

AbstractPurpose. To study the delivery efficiency of procaterol aerosols administered through the tracheal tube (ETT) with a metered-dose inhaler (MDI) during apnea. Methods. First, in a normal room air environment (at ambient temperatures of 24° to 26°C), we measured the amount of aerosol delivered through the ETT by comparing the weight of a 2-l bottle before and after firing the MDI directly into the 15-mm adapter of the ETT. The distal half of the ETT was inserted in the bottle. This procedure was repeated using five different ETTs with an internal diameter of 4–8.5 mm. The delivery efficiency was obtained by dividing the amount of aerosol delivered through the ETT by the total aerosol output per MDI puff. Next, we investigated whether the connector attached to the 15-mm ETT adapter could reduce the delivery, by repeating the same procedure with 4-mm and 5-mm ETTs. Finally, we compared the efficiencies of aerosol delivery through the 5-mm ETT and the 7.5-mm ETT in a normal room air environment with results obtained under a humidified condition (100% humid air at 37°C). Results. The percentages of aerosol delivered through the ETTs in a normal room air environment were 40%–60%, except for the 4-mm ETT, for which the percentage was 32.7% ± 6.6% (P < 0.05 vs that with the 5-mm ETT or the 6-mm ETT). A connector attached to the 15-mm ETT adapter significantly decreased the delivery efficiencies (19.0% ± 5.8% vs 32.7% ± 6.6% with the 4-mm ETT, 24.6% ± 11.8% vs 51.7% ± 10.8% in the 5-mm ETT) when compared with those without a connector. The delivery efficiencies under the humidified condition in the 5-mm ETT and the 7.5-mm ETT were 65.5% (P < 0.05) and 89.8% of those in the normal room air environment, respectively. Conclusion. The efficiency of delivery of procaterol aerosol through the ETTs was unexpectedly high (approximately half of the total aerosol output per MDI puff in the 5-mm to 8.5-mm ETTs, and one third of the total aerosol output per MDI puff in the 4-mm ETT). A connector attached to the 15-mm ETT adapter noticeably decreased the delivery efficiency. In the smaller-sized ETT, delivery efficiency was significantly lower under the humidified condition than in the normal room air environment.

One-lung ventilation with the Univent tube in a pediatric patient undergoing video-assisted thoracoscopic surgery

required. In order to obtain a deflated lung for VATS, it was imperative to use an uncuffed Univent tube 8mm in external diameter, because the patient’s tracheal size was 10mm, as observed from the preoperative chest Xray (Fig. 1). No premedication was given. Anesthesia was induced by injecting 60mg of propofol, 25 μg of fentanyl, and 3mg of vecuronium intravenously. A small, uncuffed Univent tube, 3.5 mm in internal diameter was the placed in the trachea (Fig. 2). After induction of general anesthesia, a blocker tube was advanced into the right main bronchus under bronchoscopy, and a blocker balloon was positioned in place to deflate the right lung. A 22-gauge catheter was placed in the left radial artery. General anesthesia was maintained with 40%–100% oxygen and sevoflurane; occasionally, nitrous oxide and intravenous fentanyl (total, 200 μg) were administered. After pressure controlled ventilation (PCV) had been initiated, arterial blood gas analysis under bilateral ventilation showed a pH of 7.385, PaCO2 of 43.7mmHg, and PaO2 of 158mmHg, with a peak airway pressure of 15 cmH2O, FiO2 of 0.4, and ventilation frequency of 10 ·min21. By inflating the blocker cuff, we could block the right bronchus. However, a leak of anesthetic gas around the tracheal tube became obvious at an airway pressure of 18 cmH2O, causing difficulty in maintaining the static airway pressure of 20cmH2O. We expected that the proper levels of PaCO2 and PaO2 could be maintained during one lung anesthesia by increasing the frequency of ventilation. After the posture of the patient had been changed to the lateral position, one-lung anesthesia was initiated, and the fully deflated right lung was provided with a blocker cuff of 2.5ml. However, the leak increased beyond expectation, and the patient developed hypercapnia. The results of arterial blood analysis were pH 7.291, PCO2 66.3mmHg, and PO2 107 mmHg, with PCV peak airway pressure 20 cmH2O, ventilation frequency 15 ·min21, and 100% oxygen. Gauze was packed into the

Hyperpolarizing shift by quinine in the steady-state inactivation curve of delayed rectifier-type potassium current in bullfrog sympathetic neurons

Whole-cell recordings were made from dissociated bullfrog sympathetic neurons to examine the actions of quinine (1-100 microM) on the steady-state activation and inactivation curves of a delayed rectifier-type potassium current (I(K)). Quinine (EC50 approximately 8 microM) caused a hyperpolarizing shift (approximately 31 mV with 30 microM) in the inactivation curve of I(K) without significantly affecting its activation curve. Quinine (20 microM) was without effects on the voltage-dependence of a rapidly-inactivating A-type potassium current (I(A)). It is concluded that quinine can selectively modulate the voltage-dependence of I(K) in amphibian autonomic neurons.

Optimum priming dose of vecuronium for tracheal intubation

To determine the optimum priming dose of vecuronium, we divided 173 surgical patients into five groups according to priming dose (0, 2.5, 5.0, 7.5, and 10 μg·kg−1). For endotracheal intubation, we administered a priming dose of vecuronium, and then after 4 min, the remainder was injected for a total dosage of 0.15 mg·kg−1. Onset time was determined by a 95% depression of twitch height as shown by electromyography (EMG) of the hypothenar muscles. This was measured by repeating the train-of-four (TOF) stimulation. An increased priming dose shortened the onset time; however, this shortening rate diminished when the dosage was above 7.5 μg·kg−1. In the zero priming dose group there was a significant correlation between onset time and age, and between onset time and body mass index (BMI) in women (r=0.62 and −0.45, respectively); however, this correlation was not observed in men. A priming dose of 10 μg·kg−1 showed a decrease of TOF ratio to 95% or less in 1 out of 25 cases. Although one-third of the patients in the 5 and 7.5 μg·kg−1 groups complained of clinical symptoms such as ptosis, this was clinically allowable. We conclude that the optimum priming dose of vecuronium is 7.5 μg·kg−1; however, in obese patients, a smaller dosage would be recommended.

Malignant hyperthermia with normal calcium-induced calcium release rate of sarcoplasmic reticulum in skeletal muscle

tance of suxamethonium 100 mg. Pancuronium was used as an intraoperative muscle relaxant. The surgery lasted approximately 2 h, 30min. His rectal temperature increased from 37.8°C just after the induction of anesthesia to 39°C just before the end of surgery. His temperature increased further after the reversal of the pancuronium with atropine and neostigmine. He became tachypneic and his skin color revealed cyanotic change in the peripheral regions of his extremities and in his lips. His temperature transiently reached 40.5°C, in spite of whole-body cooling carried out with a cooling mat and ethanol evaporation. Analysis of his arterial blood gas revealed pH 6.55, base excess (BE) 29.8mEq/l. He showed almost complete recovery 7h after whole-body cooling and the intravenous administration of bicarbonate (530mEq in total). In the recent series of operations, performed at our institution, an emergency appendectomy operation was performed (first operation) without any problem, with the patient under spinal anesthesia combined with epidural anesthesia. Postoperative pathological examination diagnosed appendicular cancer. Eighteen days after the first operation, right hemicolectomy was performed (second operation). Anesthesia was induced with 120 mg of propofol, after the intravenous administration of dantrolene 60mg, and was maintained with fentanyl, propofol, epidural block, and N2O—O2. His airway was managed with a laryngeal mask. His rectal temperature decreased from 36°C to 35.2°C during the 2-h, 23-min operation. Results for serum electrolytes, serum creatine kinase (CK), arterial blood gas analysis, and urinary analysis were all normal. Two hours after the end of the operation, his temperature had increased to 38.2°C in the intensive care unit (ICU), and this was associated with shivering. Intramuscular sulpyrine and intravenous flurbiprofen decreased his temperature slightly. Sixty milligrams of dantrolene, however, was ineffective. His temperature had gradually returned to normal by day 6 after the operation.

Removal of dried tenacious mucus plug from the trachea of an asthmatic patient with bronchoscopic forceps

We successfully removed a dried tenacious mucus plug from an asthmatic patient with forceps under bronchoscopic visualization. The patient was a 67-year-old man who had been treated with corticosteroids and ~-adrenergic agonists for 6 years for emphysema and fi-equent asthmatic attacks. He was admitted to a hospital because of bronchopneumonia. Twelve days after admission, his condition was complicated by status asthmaticus. He was treated with intravenous aminophylline, subcutaneous epinephrine, and terbutaline without any remarkable improvement. On the 14th day after admission, endotracheal intubation (8.0-mm endotracheal tube) and mechanical ventilation were required because of loss of consciousness. Inhalation of 2% isoflurane in oxygen was started with an anesthesia machine the next day. His asthmatic condition responded well to this therapy, and he became dependent on isofiurane inhalation. An occasional bronchoscopic examination was performed for suction of sputum in the trachea. Meticulous respiratory care was impossible because of the shortage of medical staff and equipment. This resulted in active humidification of airways not being done during the isoflurane inhalation therapy. On the 18th day, when he was transferred to our ICU, the breath sounds were weak and wheezes were heard in all lung fields, particularly in the expiratory phase. A chest radiograph revealed overinflation of both lungs. With the use of a Servo Ventilator (MODEL 900D, Siemens-Elema, SoIna, Sweden) with its own isofturane vaporizer, inhalation of 3% isoflurane in oxygen was started under intermittent positive pressure ventilation (i.e., volumecontrolled ventilation mode) after the administration of muscle relaxant. The expired tidal volume (V~,), expired minute volume (VE), and peak airway pressure (peak P,w) were 230 ml, 3.6 1.min -1, and 60 cmH20 , respectively. The preset inspired minute volume (MV) was 12 1.min -1 at the respination rate of 16. min -z, and the ratio of inspiration to expiration time was 1:1.9 with a working pressure of 60cmH20. The arterial blood gases (ABG) were PO2 270mm Hg, PCO 2 78.2mmHg, pH 7.329, HCO3 41.5 mmol.1 -~, ~and BE +12.4 mmol.l-L This high BE value was considered to be based mainly on renal compensation for chronic respiratory acidosis. Because isofurane did not improve his condition remarkably, enflurane was started at 3%, but there was no further improvement. When airway obstruction was suspected from the clinical signs, we stopped the inhalation of enflurane and decided to perform a bronchoscopic examination to clarify the cause. A dried tenacious mucus plug was identified in the trachea at the tip of the endotracheal tube, occupying 80% or more of the tracheal lumen. After an attempt to aspirate the plug through a flexible fiberoptic bronchoscope failed, it was successfully removed with bronchoscopic forceps. A diffused redness and edema of the bronchial mucous membranes and a small amount of sputum were observed in the bronchi peripheral to the carina. Airway narrowing due to the bronchospasm was, however, not observed, and all orifices of the lobar bronchi were open. Immediately after bronchoscopy, the patients condition remarkably improved. Peak Paw dropped to 40 cmH20 and V• increased to 10 1.min 1. Preset MV was changed to 8 1.min -1. ABG 30 min later were PO 2 165mmHg, PCO2 56.2mmHg, pH 7.437, HCO338.3 mmol.1-1, and BE +12.2mmol.1 1 (FIO2 0.5). VT, VE, and peak Paw were 500 ml, 8 1-min -1, and 25 cmH20, respectively. The inhalation of isoflurane was stopped after 3 hs because of his stable condition. Although weaning from the ventilator was attempted several times, it was not successful because of his insufficient tidal volume. On the 12th day after admission to the ICU he was transferred back to the previous hospital for long-term respiratory care with the ventilator. This case suggests that bronchoscopic examination should be performed as soon as possible in patients whose status asthmaticus is refractory to any bronchodilator and any inhalational anesthetics [1,2]. Bronchial forceps should always be prepared in the ICU to remove such a dried tenacious mucus plug [3,4].

Correlation of the Speed of Onset of the Effective Relaxation with Vecuronium 0.15 mg/kg with Body Mass and the Size of the Priming Dose

It is said that priming technique shortens the onset time of relaxation with vecuronium. However, too large of a priming dose will cause some problems such as heavy eye lids, swallowing impairment and respiratory discomfort. So, we tried to find a optimal dose of vecuronium in priming technique.

Density-modulated t's array, a new technique of processed electroencephalogram, for monitoring the effects of midazolam and nitrous oxide during spinal anesthesia

We have investigated the utility of a new electroencephalogram (EEG) processing system, density-modulated ts array (DTA), which we have installed in a laptop personal computer together with density-modulated spectral array (DSA) for clinical monitoring. Ten patients scheduled for orthopedic operations on the lower extremities were anesthetized with 0.5% bupivacaine intrathecally, 50% nitrous oxide in oxygen by mask, and midazolam at a dose of 0.1 mg/kg intravenously. Immediately following the administration of the drugs, the power at the frequencies between 15 and 20 Hz increased. However, the power at these higher frequencies disappeared gradually and the power in the delta band and the smaller one in the alpha band became predominant. This pattern of dominant-band shift on the DSA and DTA was observed in all the patients. In three of the patients, the sedation level remained stable as judged by the absence of body movement, quiet, regular breathing and stable hemodynamics as well as steady EEG frequency distribution throughout the operations. They awoke from anesthesia rapidly on withdrawal of nitrous oxide, with return of the power at the higher frequencies. In the other seven patients, the power at the higher frequencies suddenly reappeared on the DSA and DTA during operation and slight movements of the head and upper limbs were observed with rises in blood pressure and heart rate. In three of these seven patients, the EEG change notably preceded the physiological activities by a few minutes. On the DTA, the occurrence of any significant clinical phenomenon was displayed in a color representing at value greater than ±3. The DTA, testing power changes in the EEG at each 1-Hz interval for significant difference, permits the visual and quantitative assessment of EEG changes.