A comparison of two silicone-reinforced tracheal tubes with different bevels for use with the intubating laryngeal mask.

Seventy consecutive patients were randomly allocated for intubation through the intubating laryngeal mask airway using a straight reinforced silicone tracheal tube with either a conventional or a modified bevel. The conventional bevel was firm, wedge-shaped and with a leading edge at the side. The modified bevel was soft, hemispherical and with a leading edge in the midline. The intubating laryngeal mask position was adjusted until optimal ventilation was obtained and intubation was attempted using the randomised device. If tactile resistance was felt, a predetermined sequence of adjusting manoeuvres were utilised before a subsequent attempt. The first-attempt successful intubation rate with the conventional bevel was 23/37 (62%) and with the modified bevel was 28/33 (85%). The second-attempt successful intubation rate for the conventional bevel was 12/37 (32%) and for the modified bevel was 4/33 (12%). Intubation failed after three attempts for one patient in each group. Fewer overall intubation attempts were required with the modified bevel (p = 0.033). We conclude that intubation success rates through the intubating laryngeal mask with a straight silicone-reinforced tube are higher with a soft, hemispherical bevel with a leading edge in the midline compared with the firm, wedge-shaped bevel with a leading edge at the side.

[A multicenter study for evaluating a new intubating laryngeal mask airway].

A multicenter study was performed to evaluate the success of endotracheal intubation using an intubating laryngeal mask (ILM, Fastrach) in patients in ASA status I or II, aged 20 years or more, who underwent general anesthesia. A total of 191 patients were studied, and 24 of them were estimated difficult to intubate by the ordinary method with laryngoscope. Endotracheal intubation was successfully performed through ILM in 162 of the 191 (success rate of 84.8%). The mean time required for intubation in these successful cases was 19.1 seconds. The success rate did not depend on the clinical experience of anesthesiologists, and the individual success rate was improved as they became more experienced. Of the 24 patients who had been estimated difficult to intubate with laryngoscope, 23 were successfully intubated with success rate of 95.8%. In summary, endotracheal intubation through ILM was easy regardless of the anesthesiologist's experience, and seemed to be valuable for patients who were difficult to intubate.

Tracheal intubation through the intubating laryngeal mask airway (LMA-Fastrach) in patients with difficult airways.

The intubating laryngeal mask airway was used in 31 adult patients in whom tracheal intubation was known or suspected to be difficult. The intubating laryngeal mask airway was successfully inserted in 30 patients and provided a clinically patent airway. In the remaining one patient it was impossible to insert the device correctly. Tracheal intubation through the device was successful in 28 of 30 patients (93%). These results suggest that the intubating laryngeal mask airway has a potential role for tracheal intubation in adult patients with difficult airways.

[A reliable method for internal jugular vein catheterization for neonates and infants using a small-caliber Doppler probe].

Eighteen neonates and infants scheduled for cardiac surgery, ranging from 1 to 42 months in ages and from 1.9 to 14.6 kg in weight, were placed in supine position under general anesthesia. The neck was moderately extended with the head turned to the left. The pathways of the right carotid artery and the internal jugular vein (IJV) were located with a Doppler probe (2.0 mm in diameter, HAYASHI Electric, TOKYO) using 10 MHz ultrasound wave. The pathways of the vessels were drawn on the skin surface and the IJV was cannulated with a 24-gauge catheter over needle (Neophron, Ohmeda, USA) along the drawn pathway. A 0.015-inch guidewire was passed through the 24-guage catheter, and a central venous catheter was placed in the IJV employing to the Seldinger method. In 16 out of 18 patients the pathways of the IJV was clearly differentiated from that of the carotid artery and the catheterization was successful without any undesirable events. In the remaining 2 patients the left IJV was catherized using the same method. No complications related to the catheterization were observed. Our catheterization method is thought to be highly reliable and safe in small pediatric patients.

[Combined spinal-epidural anesthesia for intra-abdominal gynecological surgeries].

Forty-five patients scheduled for intra-abdominal gynecological surgeries, ranging in age from 30 to 60 years, were anesthetized with combined spinal-epidural (CSE) method using combined spinal-epidural needles inserted at the L2-3 interspace. Ten minutes after intrathecal administration of 0.4% isobaric tetracaine solution (2.5 ml) the upper level of analgesia was examined by pin prick method and the patients were divided into the group A (N = 7; anesthetic level > or = Th7), B (N = 7; Th8-10) and C (N = 31; Th11-L1) according to their anesthetic levels. Target anesthetic level (Th4-7) was obtained in group B by peridural administration of 2% mepivacaine in a dose of 5 ml and the surgery was performed. However, in group C, mepivacaine 7 ml was insufficient to obtain the target anesthetic level and additional mepivacaine was necessary for the surgery. In group A, no mepivacaine was used in the first hour of the surgery. In all patients, except one in group C, in whom general anesthesia was used after insufficient segmental analgesia, anesthesia was maintained by the CSE technique. We concluded that adequate anesthetic level for the intra-abdominal surgery can be obtained by intrathecal isobaric tetracaine administration combined with peridural mepivacaine of a dose calculated according to the anesthetic level ten minutes after the spinal block.

Correct positioning of the epiglottis for application of the Brain laryngeal mask airway.

Positioning of the epiglottis when the Brain laryngeal mask airway is in place was studied in 20 adult patients, using a new technique of insertion. The laryngeal mask was inserted when the anterior displacement of the mandible extended the epiglottis, thereby the providing an excellent airway in all patients. In 10 out of these 20 patients, the conventional technique of insertion revealed an incomplete extension of the epiglottis, and inadequate opening of the laryngeal inlet. It was concluded that the anterior displacement of the mandible during insertion of the laryngeal mask enhances the opening of the larynx, the result being an excellent airway.

[Pathway of the radial artery located with a small-caliber Doppler probe for arterial cannulation in pediatric patients].

The pathway of the radial artery of 23 patients, ranging in age from 17 days to 10 years, was located with a small-caliber Doppler probe, 1.5 mm in diameter, and the artery was punctured along the pathway traced on the skin surface. In all patients the arterial pathway, including its branch and diameter, was shown clearly. In 11 patients, ranging in weight from 5 to 24 kg, the artery was greater than 0.5 mm in diameter and was cannulated easily. In another 4 patients, all less than 3 kg in weight, the artery under the thin skin layer was cannulated successfully in three of them. However, among the remaining 8 patients, ranging in weight from 3 to 5 kg, cannulation was successful in only two cases. The thick tissue layer, including the skin and the subcutaneous layer over the small artery, was thought to interfere with the accurate location of the artery in the other six patients. Nevertheless, the arterial pathway traced on the skin surface facilitated successful percutaneous cannulation by another method in these six. Visualization of the arterial pathway by the small-caliber Doppler probe was thought to be helpful for percutaneous cannulation, with or without another cannulation method.

[Severe bronchospasm induced by extracorporeal circulation for cardiac surgery].

Cardiac surgery was performed on a 50-yr-old man suffering from mitral valve stenosis. He has no history of allergic disease or bronchial asthma. Mitral valve was replaced uneventfully under extracorporeal circulation, and ventilation with pure oxygen was tried. But the lung was so stiff that the bag of anesthetic circuit could not be squeezed by hand. Fiberoptic bronchoscopy revealed no obstruction in endotracheal tube or bronchial tree. A presumptive diagnosis of severe bronchospasm was made, and partial extracorporeal circulation was maintained. Soon after aggressive bronchodilator therapy, there was noticeable improvement in pulmonary compliance, and the patient was removed from bypass uneventfully. No further recurrence of bronchospasm was seen in the intra- or postoperative period. Although the exact causes for bronchospasm in our case are not clear, we concluded that severe bronchospasm was induced by extracorporeal circulation. Possible etiologies and the management of patients with this problem are reviewed.

[Transvenous monitoring of left atrial and central venous pressure with a double-lumen catheter].

We developed a new method to monitor left atrial pressure in the patients undergoing open heart surgery. The advantages of our method are 1) freedom from complications relating its removal (eg. bleeding) because of its transvenous insertion, and 2) simultaneous monitoring of both right and left atrial pressures by a single catheter. We designed to place the second port of a two-lumen central venous catheter 5 or 7 cm proximal to the tip. The catheter is inserted into the right atrium before surgery and the tip is advanced in the left atrium through the foramen ovale intraoperatively. We used this catheter in 16 infants and children, and found that effective hemodynamic monitoring was obtained without any complications. We recommend this method for the postoperative management of open heart surgery in the pediatric patients.

Trans-septal left atrial catheterisation.

A newly designed 4 FG double-lumen catheter with the second port located either 5 or 7 cm proximal to the tip was tested in five children undergoing open heart surgery. The catheter was inserted percutaneously and initially positioned in the superior vena cava, right atrium or inferior vena cava. During cardiopulmonary bypass, the tip of the catheter was repositioned manually in the left atrium across the interatrial septum. In all patients, left atrial pressure was monitored successfully while central venous pressure was monitored with the second port positioned in the superior vena cava. Removal of the catheter from the left atrium was easily performed and caused no problems.

[A case report of a burn produced by the probe of a pulse oximeter].

We experienced a case of burn produced by the pulse oximeter probe at the finger of a patient. Patient was a 75-year old man scheduled to transurethral prostatectomy. The pulse oximeter probe made by Physio-Control Co. was attached at his finger and was connected to a pulse oximeter manufactured by Ohmeda Co. Soon after the start of Spo2 measurement the anesthetist became aware of abnormal heating of the probe and removed it immediately. But unfortunately a small thermal injury was formed at patient's finger. Abnormally excessive current went through the detector diode and heated the finger probe. Attention to correct connection between the pulse oximeter probe and the finger is necessary before use.

Distribution of hypobaric tetracaine within cerebrospinal fluid in a spinal canal model.

We studied the distribution of hypobaric tetracaine within cerebrospinal fluid (CSF) using a spinal canal model to examine the spread of a hypobaric anesthetic solution during spinal anesthesia. In our study, 0.2% tetracaine colored with methylene blue was observed to migrate upwards rapidly and spread horizontally in the upper portion of the model placed horizontally and filled with CSF which was collected from several neurosurgical patients. The boundary between the hypobaric solution and CSF could be clearly identified. These results suggest that the hypobaric tetracaine will distribute in the upper portion of the spinal canal during spinal anesthesia. It can be used to produce unilateral spinal blockade in the lateral decubitus position despite a small difference in specific gravity between the hypobaric anesthetic and CSF. In addition, the fact that the hypobaric solution showed a rapid horizontal spread suggests that correct positioning both during and following administration of the anesthetic is important to control the level of anesthesia.

[Effect of midazolam as a premedicant].

A new benzodiazepine-type drug, midazolam, was administered intramuscularly as a premedicant to 155 patients aged from 16 to 81 years with ASA status 1 or 2. The hypnotic action and the effect on the upper airway tract of midazolam were evaluated. Hypnosis appeared 5 minutes after the administration of midazolam, reached its plateau after 20 minutes and started to decline after 30 minutes. The hypnotic effect showed dose-dependent increase in doses ranging from 0.05 to 0.20 mg.kg-1. No age-dependent differences in hypnosis were observed except for teenage group which showed stronger hypnosis than the other age groups. There was no problem on the upper airway tract for all age groups at the dosage of 0.05 mg.kg-1, but in the patients over 40 years increasing dosage tended to obstruct the upper airway tract. Along with the appearance of hypnosis, cough and breath holding, suggesting retention and aspiration of saliva, were observed. The appropriate dosage of midazolam for premedication was considered to be 0.05 mg.kg-1.

[Spinal anesthesia of only one lower extremity with hypobaric tetracaine].

For spinal anesthesia of only one lower extremity, effect factors, assumed to influence the level of anesthesia including the degree of head-down position of the patients during injection, the volume of the drug and the rate of its injection, are studied using 0.2% hypobaric tetracaine solution in water. Seventy-two patients having the surgery of one lower extremity were divided into 7 groups according to the difference in the degree of head-down position (0, 2 and 5 degrees), in the volume (3, 5 and 7 ml) and the rate (0.2, 0.1 and 0.05 ml.s-1) of injection of tetracaine solution. Patients, in lateral position with the operative side up during injection and 20 minutes after injection, were checked for the level of hypesthesia and analgesia on both operative side and non-operative side. Except 2 groups of the patients who were in horizontal position during injection or who are injected with 7 ml of tetracaine solution all at once, the upper level of analgesia in the operative side is well controlled at T10, although in some patients the additional injection of small amount of tetracaine solution was needed. In these patients, the analgesic level in the non-operative side is restricted within S level, and HR and BP changes were very slight. The rate of injection had no effect on the analgesic level on both operative side and non-operative side.