Biomedical subjects

H K Kil

Publications and source records attributed to H K Kil.

5 recordsLinked to original sources

PubMed1997

Dexamethasone treatment does not ameliorate subglottic ischemic injury in rabbits.

BACKGROUND: Following tracheal intubation, a small proportion of patients develop laryngeal inflammation or tissue necrosis severe enough to result in clinical symptoms. Although corticosteroids are frequently advocated to prevent such injury, human studies have been inconclusive because of the low incidence of the problem. This study developed a rabbit model of endotracheal tube-induced laryngeal injury to test the hypothesis that a corticosteroid, dexamethasone, could ameliorate the inflammation and necrosis. METHODS: Subglottic injury was induced in 21 anesthetized rabbits by inflating the cuff of an endotracheal tube to 100 mm Hg with the cuff just below the vocal cords. Every 30 min for 2 h, the cuff was deflated, the tube turned 90 degrees, and the cuff then reinflated. After 2 h, the rabbits' tracheas were extubated. Rabbits were divided into two groups: the treatment group received dexamethasone (1 mg/kg) i.v. 1 h prior to extubation with the dose repeated 6 h following extubation; the untreated group received a saline solution placebo. Four additional rabbits were anesthetized for the same period but did not have a tracheal tube inserted. All rabbits were killed 24 h later and the larynxes were harvested. Sections through the larynx at the level of the cricoid cartilage were randomized and submitted blindly to a veterinary pathologist. Larynxes were scored and ranked according to the severity of mucosal inflammation and necrosis, and submucosal hemorrhage, edema, inflammation, and necrosis. Specimens were also evaluated for focal vs diffuse disease. RESULTS: Injured rabbits demonstrated focal to diffuse mucosal and submucosal inflammation and necrosis. Inflammatory exudates were present in sections from most of the injured rabbits and large sections of the larynxes were denuded of epithelium. There were no differences in injury scores between the treated and untreated rabbits. The four uninjured control rabbits had normal larynxes. CONCLUSIONS: Two hours of endotracheal tube cuff inflation to 100 mm Hg causes an inflammatory laryngeal injury. The histologic features of the injury are unaltered by treatment with 2 mg/kg dexamethasone.

Animals↗

PubMed1995

Jet ventilation using fiberoptic bronchoscopes.

A fiberoptic bronchoscope is used to facilitate tracheal intubation in cases of difficult direct laryngoscopy. Occasionally, difficulty is encountered in advancing the endotracheal tube after the fiberoptic bronchoscope has been introduced into the trachea. This study tested the feasibility of providing jet ventilation through the suction channel of the fiberoptic bronchoscope as an interim measure under those or similar circumstances. Three commercial models of fiberoptic bronchoscopes with suction channels of 1.2-, 1.5-, and 2-mm diameter, respectively, were tested in a mechanical test lung at varying compliances and resistances using a jet injector connected to an oxygen source at 50 psi. The fiberoptic bronchoscope with the 2-mm suction channel was also studied in seven adult patients who were anesthetized and paralyzed. Jet ventilation was manually performed at the rate of 12/min for 10 min. In the mechanical test lung, the tidal volumes with 1.2-, 1.5-, and 2-mm suction channels were as follows: 280 mL, 490 mL, and 880 mL, respectively, at a compliance of 50 mL/cm H2O and normal resistance; 260 mL, 470 mL, and 820 mL, respectively, at a compliance of 50 mL/cm H2O and high resistance to simulate bronchospasm; 130 mL, 270 mL, and 890 mL, respectively, at a compliance of 20 mL/cm H2O and normal resistance; 120 mL, 220 mL, and 810 mL, respectively, at a compliance of 20 mL/cm H2O and high resistance. In anesthetized, paralyzed patients, oxygen saturation was 96% or more throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Effects of dexamethasone on laryngeal edema following short-term intubation.

Following short-term intubation for general anesthesia, respiratory difficulty may result from laryngeal or subglottic edema after extubation. We have hypothesized that this problem could be pretreated by administering a high-dose of dexamethasone intravenously before extubation. After glottic injuries were made under direct laryngoscopic view, intubation was performed and maintained for 1 hour in 33 rabbits. The rabbits were divided into 3 groups; dexamethasone (1 mg/kg) was administered to group 1(n=12) immediately after intubation and group 2(n=10) just before extubation; group 3(n=11) received normal saline, just before extubation. After extubation, subglottic excursion pressure was measured for 4 hours. 15 injured rabbit larynges and 3 normal ones were extracted for histologic section. 2 of 12 rabbits in group 1; 3 of 10 in group 2; and 5 of 11 in group 3, showed mild stridor after extubation(p>0.05). All rabbits developed maximum increase in subglottic pressure within 2 hours after extubation. Group 1 and 2 showed less increase in pressure compared to group 3(P<0.05), but here was no statistical difference between group 1 and 2(P>0.05). Histologic sections of the larynges showed less submucosal edema, including other changes in group 1 and 2, than in group 3(P<0.05). In conclusion, administering a high-dose of dexamethasone before extubation, is effective in prophylaxis and treatment of laryngeal injuries following short-term intubation in rabbits. This is especially true in edema.

Animals↗

PubMed1994

Effect of prophylactic bronchodilator treatment on lung resistance after tracheal intubation.

BACKGROUND: After induction of anesthesia, lung resistance increases. We hypothesized that prophylactic bronchodilator treatment before tracheal intubation would result in a lower lung resistance after placement of the endotracheal tube. METHODS: Forty-two adult patients were randomized to receive one of three inhaled medications 1 h before surgery. All patients first underwent pulmonary function tests. Patients then received either inhaled albuterol (360 micrograms) (n = 12), inhaled ipratropium bromide (72 micrograms) (n = 15) or a placebo inhalation (n = 15). Two, 5, and 15 min after tracheal intubation, lung resistance was measured using the method of von Neergard and Wirtz. RESULTS: Patients who received either bronchodilator had significantly lower lung resistance after intubation than those receiving placebo. At 2 min, lung resistances were 12.7 +/- 1.4 cmH2O.l-1.s-1 (mean +/- SEM) for the placebo group, 6.4 +/- 3.1 cmH2O.l-1.s-1 for the ipratropium-treated group (P < 0.05 vs. placebo), and 7.2 +/- 0.8 cmH2O.l-1.s-1 for the albuterol-treated group (P < 0.05 vs. placebo). The differences in lung resistance persisted through the final measurement at 15 min. Three of fifteen placebo-treated patients developed audible wheezing whereas no patients developed wheezing in either bronchodilator-treated group (P < 0.05 by Fisher's exact test). Although smokers and nonsmokers in the placebo group developed similar resistances after intubation, bronchodilator treatment resulted in lower resistance in nonsmokers than in smokers (P < 0.05). CONCLUSIONS: Prophylactic treatment with either an inhaled beta 2-adrenergic agonist or an inhaled cholinergic antagonist produced lower lung resistance after intubation when compared with an inhaled placebo medication. The effect was more pronounced in nonsmokers than in smokers.

Administration, Inhalation↗

PubMed1994

Head position and oral vs nasal route as factors determining endotracheal tube resistance.

STUDY OBJECTIVE: We performed this in vitro study to determine the following: (1) if there is any significant difference in resistance between comparably sized endotracheal tubes (ETTs) in simulated anatomic oral and nasal conformations: (2) if neck flexion would increase the resistance of the ETT; and (3) if a wire-reinforced tube in simulated oral conformation would minimize the resistance increase at bends in the tube. DESIGN: The pressure drops (the change in pressure the flow through the ETT) at the proximal end of three sizes of tubes (6-, 7-, and 8-mm inner diameter) were measured in anatomic conformations at flows ranging from 20 to 100 L/min with the tubes warmed to 37 degrees C. RESULTS: There were no significant differences in pressure drops between comparably sized ETTs in the nasal vs oral conformation at any flow tested. Maximal head flexion produced a small increase in pressure drop for the standard 6-mm ETT but not for the larger tubes. The wire-reinforced tubes, when compared with the standard 7- and 8-mm ETTS, actually had greater pressure drops across the tubes at high flows. CONCLUSIONS: (1) Pressure differences between ETTs in nasal and oral conformations with comparable size and length are insignificant, even at high flow rates. (2) Maximal neck flexion does not deform the tube enough to make a clinically significant difference in resistance in vitro, although the 6-mm ETT had a slightly higher resistance in flexion. (3) A size 7- or 8-mm reinforced ETT has a higher resistance compared with a standard ETT.

Airway Resistance↗