Relaxant Effects of Thiopental, Ketamine, and Propofol on Isolated Rat Tracheal smooth Muscle / 대한마취과학회지

BACKGROUND: Intravenous anesthetics may modify airway responsiveness. The author investigated the relaxant effect of thiopental, ketamine, and propofol on isolated rat tracheal smooth muscles. METHODS: The trachea of the rat was dissected and cut into 3-mm rings. The rings were mounted in a water-jacked organ bath filled with Krebs solution aerated with 95% O2 and 5% CO2 at 37degreesC. Thiopental, ketamine, and propofol were given randomly to each ring preconstricted with EC50 of acetylcholine from 10(-6) to 10(-3) M. The relaxation response was the tension during anesthetic equilibration, expressed as a percentage of the tension from EC50 of acetylcholine. RESULTS: Thiopental and propofol (10(-5) to 10(-3) M) relaxed acetylcholine-induced contractions in a dose dependent manner (P < 0.05). Ketamine in doses of 10(-5) and 10(-4) M constricted acetylcholine-induced contractions by 3.2% and 16.5% respectively (P < 0.05). But ketamine in a dose of 10(-3) relaxed acetylcholine-induced contractions by 76.4% (P < 0.05). The relaxation of tracheal smooth muscles was greatest in thiopental, and was least in ketamine (P < 0.05). CONCLUSIONS: All three intravenous anesthetics have an excellent relaxation of tracheal smooth muscles in rats, except in doses of 10(-5) and 10(-4) M of ketamine.

Effects of Ketamine on Carbachol and Epidermal Growth Factor Contraction in Rat Trachea / 대한마취과학회지

BACKGROUND: It is well known that ketamine, a dissociative anesthetic, inhibits smooth muscle contractions induced by high KCl and receptor agonists such as carbachol, histamine and endothelin. It has been reported that the inhibitory effect is mediated by a decrease in Ca2+ influx through the plasma membrane in smooth muscle. However, the mechanism of action for ketamine is not fully understood. In the present study, the effect of ketamine on Ca2+ -dependent and -independent carbachol and epidermal growth factor (EGF) contractions was investigated in rat tracheal smooth muscle. METHODS: Tracheal smooth muscle strips from Sprague-Dawley rats were mounted in an organ bath with physiological salt solution (PSS, pH 7.4, 37oC). When high KCl and carbachol (1, 10 micrometer) induced contraction and verapamil and ketamine attenuated contraction, and when EGF or carbachol alone and EGF plus carbachol in Ca2+ free media induced contration and verapamil and ketamine inhibited contration, the changes in tention of the muscle strips were measured. RESULTS: 1) Ketamine inhibited the contractions stimulated by high KCl (70 mM) and carbachol (1, 10 micrometer) in a concentration-dependent manner. The inhibitory effect was more marked in the 1 micrometer carbachol preparation than in the 10 micrometer carbachol preparation. 2) Although the contraction induced by carbachol (1 micrometer) was attenuated by verapamil (10 micrometer), a voltage-dependent Ca2+ channel blocker, the degree of inhibition was not complete, but only partial. The verapamil-insensitive portion of the contraction induced by carbachol was completely inhibited by the cumulative application of ketamine. 3) EGF (1 mg/ml), a tyrosine kinase-associated growth factor, or carbachol alone did not induce contraction in Ca2+ -free PSS (1 mM EGTA). However EGF plus carbachol contracted tracheal smooth muscle in the Ca2+ -free media and it was completely inhibited by ketamine but not by verapamil. CONCLUSIONS: These results suggest that ketamine inhibits the smooth muscle contraction including both verapamil-sensitive and -insensitive Ca2+ increments and by Ca2+ -independent contraction mechanisms.

Epithelial Modulation on Guinea-pig Tracheal Smooth Muscle Tension to Contractile Agents / 대한마취과학회지

BACKGROUND: Asthma can be described as the hypersensitivity of the airway to various stimuli. Injury to tracheal epithelial cells could be the reason for tracheal hypersensitivity in asthma or upper respiratory infection. This study is based on the hypothesis that the dysfunction of the airway in asthma is caused by epithelial cell injury. METHODS: After isolating guinea-pig tracheal preparations, in order to examine the role of airway epithelium in response to smooth muscle, we measured the contractile responses to acetylcholine, carbachol, and histamine on the isolated epithelium-denuded or epithelium-intact guinea-pig tracheal preparations. When tracheal tones were stabilized, each contractile agent was added cumulatively to the organ baths to obtain concentration-response curves, and ED50 and ED95 were calculated. RESULTS: In both groups, tracheal tones increased in response to contractile agents, in concentration- dependent manners. In comparing both groups, the contractility of denuded trachea was increased by 10 7 and 10 6 M in acetylcholine, and by 10 6 M in histamine significantly. In denuded trachea, ED50 and ED95 increased significantly in response to both acetylcholine and histamine. However, they did not increase in carbachol. CONCLUSIONS: The removal of the epithelium increased the contractile responses to acetylcholine and histamine.

The Inhibitory Effects of Midazolam and Diazepam on Smooth Muscle Tension in Rat Trachea / 대한마취과학회지

BACKGROUND: It has been demonstrated that a group of minor tranquilizers, benzodiazepines, are able to relax airway smooth muscle, but the mechanism by which these agents produce muscle relaxation are not fully understood. This study was undertaken to determine the effects and mechanism of diazepam and midazolam on Ca2+ and K+ channel in isolated rat trachea muscles by measuring isometric tension. METHODS: Our experiment was performed to evaluate the effects of midazolam and diazepam by cumulative administration from 10(-6)M to 3 x 10(-5)M to tracheal smooth muscle contraction which was induced by contractile agonists such as ACh 10(-5)M, carbachol 3 x 10(-7)M, and KCl 40 mM. The effects of midazolam and diazepam were evaluated on Ca2+ and K+ channels by inhibition of contraction using a nonspecfic K+ channel blocker such as tetraethyl ammonium (TEA) elicited by a 2 mM Ca2+ space addition to Ca2+ free on high K+ depolarizing rat tracheal muscle. Also, to elucidate any mechanism involved, the effects of flumazenil (a specific central antagonist of benzodiazepines), propranolol (a beta adrenergic antagonist), and atropine (a muscarinic antagonist) and tracheal epithelium removal were examined. RESULTS: In a concentration-dependent way, both midazolam and diazepam relaxed airway smooth muscle directly and had inhibitory effects on voltage-dependent Ca2+ (VDCC) and K+ channels. CONCLUSIONS: These results suggest that benzodiazepines relax airway smooth muscle, not via a neural pathway or benzodiazepine receptor but through a direct action on Ca2+ and K+channels. Benzodiazepine enhanced K+ conductance, leading to a decrease in VDCC opening, thus reducing Ca2+ through the voltage-dependent Ca2+ channel, in addition to inhibiting of intracellular Ca2+ release.

General Anesthetic Experience of Resection & Anastomosis in a Distal Tracheal Tumor: A case report / 대한마취과학회지

A tracheal mass was detected in a woman who complained progressive cough and dyspnea developed 3 months ago. Tumor was located just 1 cm above carina almost obstructing the tracheal lumen and it was mobile with respiration. Curative tracheal resection & anastomosis was attempted with a right thoracotomy approach. In this patient, complete tracheal obstruction by the mass can occur during the induction of the anesthesia and the pre-resection period; therefore, we made cardiopulmonary bypass available before the induction. We successfully maintained the airway and provided the adequate ventilation during that critical period without using cardiopulmonary bypass. Here we report this case with a literature review.

Effects of Isoflurane and Propofol on Hydrogen Peroxide-Induced Injury of Trachea in Guinea-Pig / 대한마취과학회지

BACKGROUND: Oxygen free radicals are likely to be involved in decreases of the tracheal epithelial barrier function, increases of permeability, and inhibitions of ciliary activity. The present study was undertaken to determine the interaction between isoflurane, propofol and oxidative injury with respect to the contractile force of tracheal smooth muscle in guinea-pig. METHODS: Strips of guinea-pig trachea were suspended in organ chambers, and their isometric tension was recorded by a MacLab. Tissues were allocated to 7 groups (each: n = 10) of control, 2%, 3%, and 4% isoflurane, 25 micrometer, 50 micrometer, and 100 micrometer propofol. All strips were challenged with 10 5 M acetylcholine (ACh) to get maximal contractions and followed washout. All strips were exposed to 10 4 M H2O2 contained modified Krebs solution for 30 minutes after the strips were perfused with each concentration of anesthetics for 20 minutes. After washout of organ chambers and 30 minutes of rest, all strips were contracted with ACh. Several strips were prepared for microscopic evaluation. RESULTS: The contractile heights to H2O2 showed 36.7+/-20.2% of control value in the control group, and there were significant differences between the control and the propofol 100 micrometer group as shown by Tukey test. There were no significant differences in contractile heights to the second ACh in any of the 6 groups except the 100 micrometer propofol group. Microscopic morphological changes were not detected by 1,000 light microscopic evaluation. CONCLUSIONS: We suggest that the contractile heights of strips to H2O2 which were lower in four anesthetic groups than in the control group indicated a counteracting relaxation of smooth muscle caused by anesthetics. We suggest that there might be some functional effects of H2O2 on smooth muscle cells other than epithelial injury and that 100 micrometer propofol might have some protective effects against smooth muscle cell injury from 10- 4 H2O2.

Effects of Isoflurane and Propofol on Hydrogen Peroxide-Induced Injury of Trachea in Guinea-Pig / 대한마취과학회지

BACKGROUND: Oxygen free radicals are likely to be involved in decreases of the tracheal epithelial barrier function, increases of permeability, and inhibitions of ciliary activity. The present study was undertaken to determine the interaction between isoflurane, propofol and oxidative injury with respect to the contractile force of tracheal smooth muscle in guinea-pig. METHODS: Strips of guinea-pig trachea were suspended in organ chambers, and their isometric tension was recorded by a MacLab. Tissues were allocated to 7 groups (each: n = 10) of control, 2%, 3%, and 4% isoflurane, 25 micrometer, 50 micrometer, and 100 micrometer propofol. All strips were challenged with 10 5 M acetylcholine (ACh) to get maximal contractions and followed washout. All strips were exposed to 10 4 M H2O2 contained modified Krebs solution for 30 minutes after the strips were perfused with each concentration of anesthetics for 20 minutes. After washout of organ chambers and 30 minutes of rest, all strips were contracted with ACh. Several strips were prepared for microscopic evaluation. RESULTS: The contractile heights to H2O2 showed 36.7+/-20.2% of control value in the control group, and there were significant differences between the control and the propofol 100 micrometer group as shown by Tukey test. There were no significant differences in contractile heights to the second ACh in any of the 6 groups except the 100 micrometer propofol group. Microscopic morphological changes were not detected by 1,000 light microscopic evaluation. CONCLUSIONS: We suggest that the contractile heights of strips to H2O2 which were lower in four anesthetic groups than in the control group indicated a counteracting relaxation of smooth muscle caused by anesthetics. We suggest that there might be some functional effects of H2O2 on smooth muscle cells other than epithelial injury and that 100 micrometer propofol might have some protective effects against smooth muscle cell injury from 10- 4 H2O2.

Intubating Laryngeal Mask Airway in Difficult Intubation: A case report / 대한마취과학회지

The incidence of difficult laryngoscopy or intubation varies from 1.5% to 13%, and failed intubation has been identified as one of the anesthesia-related causes of death or permanent brain damage. The Intubating Laryngeal Mask Airway (ILMA) is a new modified laryngeal mask with the capability for guided tracheal intubation while maintaining ventilation. The ILMA was designed by Brain to improve blind endotracheal intubation through a laryngeal mask. We report the successful use of this device in two patients with difficult airway during induction of general anesthesia.

Intubating Laryngeal Mask Airway in Difficult Intubation: A case report / 대한마취과학회지

The incidence of difficult laryngoscopy or intubation varies from 1.5% to 13%, and failed intubation has been identified as one of the anesthesia-related causes of death or permanent brain damage. The Intubating Laryngeal Mask Airway (ILMA) is a new modified laryngeal mask with the capability for guided tracheal intubation while maintaining ventilation. The ILMA was designed by Brain to improve blind endotracheal intubation through a laryngeal mask. We report the successful use of this device in two patients with difficult airway during induction of general anesthesia.

The Effects of Vecuronium and Pancuronium on the Tension of the Isolated Rat Tracheal Smooth Muscle / 대한마취과학회지

BACKGROUND: Non-depolarizing muscle relaxants have their muscle relaxing effect by competing with acetylcholine (ACh) at the nicotinic receptor level. What are the effects of such muscle relaxants on the tracheal smooth muscle? This present study was set up to address the question as to how vecuronium and pancuronium influence the tracheal smooth muscle. METHODS: Sixty male Sprague-Dawley rat tracheal smooth muscles were isolated at optimal length for isometric force. The preparations were set up in an organ bath containing Tyrode's solution. And isometric force displacement transducer and physiograph were used to record the change in force. After the equilibration period the preparations were contracted with ACh 10(-5) M and carbachol 3x10(-7)M seperately. The preparations were washed with fresh tyrode's solution and allowed to return passively to resting tone. Then the cumulartive effect of ACh (from 3 10(-7) M through 10(-5) M) and carbachol (CCh, from 10(-8) M through 3 10(-6) M) were produced before and after pretreating the preparation with vecuronium (10(-5) M and 10(-6) M) and pancuronium (10(-5) M and 10(-6) M) respectively. Also, we studied the changes of contraction produced by neostigmine before and after pretreatment with vecuronium (10(-5) M and 3 10(-5) M) and pancuronium (3 10(-6) M and 3 10(-5) M). RESULTS: Vecuronium shifted the ACh dose-response curve of the tracheal contraction to the left (p0.05). CONCLUSIONS: Vecuronium inhibits the ACh hydrolyzing enzyme, especially acetylcholinesterase. Therefore it potentiates ACh contraction in the tracheal smooth muscle, but not the CCh contraction, while pancuronium has a different effect in comparison with vecuronium. That is, at a low concentration it reveals an antagonistic effect on the muscarinic M2 receptor and at a higher concentration it has an antagonistic effect on the muscarinic M3 receptor in the tracheal smooth muscle.

The Effects of Temperature Changes on the Acetylcholine and Neostigmine Induced Contraction of Rabbit Trcheal Smooth Muscle / 대한마취과학회지

BACKGROUND: The body temperature of a patient changes changes during general anesthesia and cholinesterase inhibitor is usually administered at the end of general anesthesia to reverse the neuromuscular blocker effect. We tried to evaluate the effect of temperature changes on the contraction of tracheal smooth muscle induced by acetylcholine (Ach) exogenously administered and neostigmine, cholinesterase inhibitor. METHODS: Isolated tracheal preparations(3 mm wide) of rabbit were mounted in organ baths filled with Tyrode's solution. Cumulative dose responses(isometric contractin) of Ach (10-6, 10-5, 10-4 & 10-3 M) & neostigmine (10-8, 10-7, 10-6, 10-4) at 37oC, 39oC and 27oC were measured with force displacement transducer and pD2 was calculated. RESULTS: Warming from 37oC to 39oC, contraction by Ach weakened significantly and contraction by neostigmine did not change significantly. Cooling from 37oC to 27oC, contraction by Ach were changed significantly and contraction by neostigmine, at low concentration, was inhibited significantly, but at high concentration, was not potentiated significantly. pD2 of Ach did not change significantly by cooling from 37oC to 27oC and decreased significantly by warming from 37oC to 39oC. pD2 of neostigmine was significantly reduced by cooling from 37oC to 27oC and did not change significantly by warming from 37oC to 39oC. CONCLUSIONS: Warming from 37oC to 39oC, the contraction of tracheal smooth muscle induced by Ach was decreased significantly,and cooling from 37oC to 27oC, contraction induced by neostigmine was decreased significantly at low concentration of neostigmine. But it is not sure wheter these effects can be observed in clinical practice when neostigmine is administered to patients,so further study is necessary.

Effects of Ketamine on Intracellular Ca2+ Pooling in Guinea Pig Trachea / 대한마취과학회지

BACKGROUND: The potent bronchodilatory effects of ketamine on airway smooth muscle tone are important in the management of patients with asthma, but its mode of action is unclear. In the present study we evaluated that effects on isolated guinea pig tracheal smooth muscle. METHODS: Changes of isometric contraction of strip were measured. (1) Serial stimulation with acetylcholine(ACh) in Krebs solution or with A23187, nifedipine, ketamine were evaluated. After that, ACh stimulation was induced in Ca2+ free solution. (2) In Ca2+ free solution, ACh contraction was obtained(L1) and emptied by repetitive ACh stimulation. Internal stores were refilled by Ca2+ with ACh stimulation. During the incubation period, A23187, nifedipine, ketamine, cyclopiazonic acid + ketamine was added and tested for their ability to inhibit refilling. Refilling was evaluated by ACh produced contraction (L2) with ratio (L2/L1). (3) Effects of ketamine on the contraction induced by caffeine were also checked. RESULTS: Ketamine inhibited amplitude dose-dependently by successive application of ACh in modified Krebs solution and Ca2+ free solution. Ca2+ influx through voltage gated channels were inhibited with nifedipine but not with A23187. ACh sensitive internal store were different when A23187, nifedipine and ketamine were applied in Ca2+ free solution. Refilling of internal store were potentiated by A23187, but decreased by nifedipine and ketamine. Caffeine produced contractions in the presence of ketamine were not significantly different from control. CONCLUSION: We concluded that the inhibitory effects of ketamine in guinea pig trachea were by acting through voltage and receptor gated channels in dose-depedent manner and these effects may be interferences of intracellular second messengers system.

One Lung Ventilation of Bronchial Trifurcation Patients at the Carina: Two cases report / 대한마취과학회지

Anomalous right upper lobe bronchus takeoff from the trachea has been reported to occur in 1 of 250 otherwise normal patients. Difficulty with double-lumen tube(DLT) placement has been described previously and there are problems with Univent tube with the intention of using the bronchial blocker to achieve right lung collapse in this patient. In two cases, the fiberoptic bronchoscopic examination through Univent tube revealed a trifurcation, rather than the usual bifurcation, at the carina and revealed that the most rightward lumen was the right upper lobe bronchus and the middle lumen was the right middle and lower lobe bronchus. The left lumen was the left main bronchus. So in one case, the Univent tube was withdrawn and DLT was reinserted. In the other case right lung collpase achieved with the inflation of cuff of bronchial blocker. One lung anesthesia was performed without any problem in these two cases.

Metric Study of Upper Airway and Trachea in Nomal Korean Adults uing Fiberoptic Bronchoscopy: Study of endotracheal tube fixation positioning in adults / 대한마취과학회지

BACKGROUND: Neck flexion risks endobroncheal intubation when the tracheal tube is not in the proper position. So accurate knowledge of upper airway length is required to prevent malpositioning of endotracheal tubes. Therefore we evaluated the length of various portions of upper airway in Korean adults (n=500) who had no abnormality of upper airway. METHODS: Five hundred patients, composed of 198 males and 302 females who underwent elective surgery, were included in this study. After endotracheal tube was placed under general anesthesia, we measured the distance from tube machine-end to upper incisor (value 1), from tube machine-end to inferior margin of cricothyroid membrane (value 2), and from tube machine-end to carina (value 3) by means of fiberoptic bronchoscopy. RESULTS: The mean length between upper incisor and inferior margin of cricothyroid membrane (value 2 - value 1) was 12.7 cm in males and 11.6 cm in females, while the mean length between superior margin of cricoid cartilage and carina (value 3 - value 2) was 12.9 cm in males and 11.3 cm in females. So the mean length between upper incisor and the mid portion of trachea was nearly 19.6 cm in males and 17.7 cm in females. CONCLUSIONS: We believe that, based on the findings in this study, the safety length for endotracheal tube fixation is 20 cm in Korean adult males and 18 cm in Korean adult females.