Tetsuo Takaya

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.

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.