Rabbit model of airway stenosis induced by scraping of the tracheal mucosa

BACKGROUND: Prolonged endotracheal intubation in children often induces intractable airway stenosis. The aim of the present study was to establish a new model of airway stenosis for developing an effective method of treatment. MATERIAL AND METHODS: The rabbit trachea was annularly incised, and the tracheal mucosa was scraped with a nylon brush. The trachea was then closed. Nine days after scraping, the trachea was microscopically examined. RESULTS: All of the examined rabbits showed tracheal stenosis, ranging from 22% to 82% in diameter and from 48% to 97% in cross-sectional area. The stenotic lesion was confined within the scraped region, not including the sutured region. Histologic examination showed inflammation in the stenotic lesion with submucosal hyperplasia caused by proliferation of fibroblasts and thickening of collagen fibers. CONCLUSION: This method can be easily carried out and assures induction of airway stenosis. This model may be useful for developing methods for treating airway stenosis in the early stage.     

Submental intubation in complex craniomaxillofacial trauma

The submental route for endotracheal intubation is an alternative to nasal intubation or tracheostomy in the surgical management of patients with complex craniomaxillofacial injuries. The critical indication for submental intubation is the requirement for intraoperative maxillomandibular fixation (MMF) in the presence of injuries that preclude nasal intubation and in a situation where a tracheostomy is not otherwise required. MMF to re-establish dental occlusion is essential for a normal functional result in dentate patients with fractures involving alveolar segments of the jaws. However, MMF precludes orotracheal intubation. Nasotracheal intubation is often used but is contraindicated in the presence of skull base fractures and will interfere with the access to certain fracture types. A tracheostomy has a high potential complication rate and in many patients, an alternative to the oral airway is not required beyond the perioperative period. A submental intubation has been used in 11 selected cases amongst 190 consecutively treated patients with craniomaxillofacial trauma over a 3-year period. These cases have been retrospectively reviewed and there have been no significant complications. The indications and technique used are described. Submental intubation is a simple and useful technique with low morbidity in selected cases of craniomaxillofacial trauma and the author's clinical experience with this technique is described.     

Value of endotracheal tube safety in laryngeal laser surgery

BACKGROUND AND OBJECTIVES: Due to the increased popularity of laryngeal laser therapy, surgeons and anesthesiologists are inevitably confronted with questions concerning the choice of the most efficient endotracheal tube (ETT) for laryngeal laser surgery, especially with regard to possible endolaryngeal tube fires, or combustions. The purpose of this study was to determine the current practice in endolaryngeal laser surgery in Germany. STUDY DESIGN/MATERIALS AND METHODS: A questionnaire was sent to 152 ENT Departments in Germany, care was taken that the responders could send back the questionnaire anonymously. Among other questions the participants were asked for the number of lasersurgical treatments of the larynx performed in the past, the usual type of ETTs in use, whether other safety precautions were taken during CO2 laser surgery of the larynx and for intraoperative complications like tube ignition, fires or combustions. RESULTS: Eighty six of the 152 addressed ENT departments replied. In laryngeal laser surgery, 59/86 departments regularly use special laser tubes in daily routine (74.5%). In about 20,000 lasersurgical procedures, 15 incidents of ETT fire have been reported. In six of the reported 15 cases a tube fire occurred despite the fact that special laser tubes had been utilized. CONCLUSIONS: The present study could demonstrate that the use of special laser tubes does not necessarily protect against ETT fire. Thus, even when using special laser tubes other safety measures should be taken. In view of the maximum safety for the patient it has to be stated, that the safety during surgery correlates definitely with the experience of the surgeon. The weakest point of ETTs is usually situated in the cuff region.     

A meta-analysis of the effects of various interventions in preventing endotracheal suction-induced hypoxemia

The purpose of this study was to clarify the effects of interventions that were applied to prevent endotracheal suction-induced hypoxia by meta-analysis. To obtain a sample for this meta-analysis, a computerized search was performed through MEDLINE in addition to tracking down additional references cited in bibliographies of past reports. Finally thirty research reports were examined. In terms of the application time of oxygenation, insufflation and preoxygenation were the most prevalently used in the studies. Regarding the methods of oxygenation, the most prevalent technique for oxygenation was hyperoxygenation in combination with hyperinflation. Hyperoxygenation and hyperinflation were most frequently induced by FiO2 of 1 and a 150% tidal volume of three to six breaths, respectively. Suctioning was commonly sustained for <15 seconds using pressures of -80 to -120 mmHg and with size 14 French catheters. Insufflation was less effective than the other methods examined in the present study. From this study, it can be concluded that the interventions that were applied to prevent endotracheal suction-induced hypoxia, regardless of their application times or methods, reduced suction-induced hypoxia significantly.     

F AILED P REHOSPITAL I NTUBATIONS : A N A NALYSIS OF E MERGENCY D EPARTMENT C OURSES AND O UTCOMES

Objective. To examine the reasons for failed prehospital endotracheal intubation (ETI) and to identify how the airway was subsequently managed in the emergency department (ED). Methods. Data were collected from January to December 1998 for a county-wide paramedic system. Failed prehospital ETIs and perceived reasons for failure were identified. Subsequent ED airway management was reviewed. Results. During the study period there were 13,112 patient contacts resulting in ETI attempts on 592 patients, of whom 536 (90.5%) were successfully intubated. Of the 56 failed field intubations, 49 (87.5%) had ED charts available for review. Endotracheal intubation failure was associated with inadequate relaxation in 24 (49%), difficult anatomy in ten (20%), and obstruction in five (10%). Successful ETI was achieved in the ED in 42 cases (86%). Twenty cases (41%) were facilitated by rapid-sequence intubation (RSI) in the ED. For those with incomplete relaxation in the field, 13 of 24 (54%) were intubated in the ED using RSI. Factors associated with the use of ED RSI include attempted prehospital nasotracheal intubation or attempted prehospital midazolam-facilitated intubation (p < 0.001). The predicted need for RSI in this prehospital system is approximately 3.9%. In eight cases, three or more ETI attempts or the use of rescue airways was required in the ED. The predicted minimum incidence of “truly difficult” intubation in this system is approximately 0.8–1.6%. Conclusions. Paramedic intubation failures result from a variety of factors. Less than half of field intubation failures were remedied in the ED by the use of neuromuscular-blocking agents. A similar number were intubated without the use of RSI. A fraction of failed field ETIs may have resulted from inadequate operator training or experience. A small percentage of field patients were “truly difficult” and required advanced resources in the ED to facilitate airway management. Medical directors should be cognizant of the numerous factors affecting intubation performance when designing and implementing approaches to difficult prehospital airways.     

一次性无菌透明贴膜在气管套管封堵时的应用

气管切开是脑外科抢救危急重症患者重要而有效的措施,但长期放置气管套管可引发并发症,气管切开者拔管前一般先行封堵,封堵材料一般有橡皮塞、棉签、一次性输液器茂菲氏滴管[1]等,但消毒灭菌过程繁琐,固定不牢.2009年12月开始我科采用一次性无菌透明贴膜作为气管套管封堵材料,应用效果满意,现报告如下.     

Laser Resistance of Endotracheal Tubes II: ObservedTemperature Rise and Theoretical Explanation

An infrared camera was used to measure the temperature rise which takes place in endotracheal tubes exposed to a 20 W CO₂ laser beam. It was seen that a metallic tube was heated up within 1 s to temperatures of 200–300°C which was very destructive to the PVC conduits inside the tube. A compound tube, on the other hand, reached temperatures of only 60°C at its inner surface after an exposure of 20 s. The experimental results can be explained by a physical model which uses the heat conduction and the heat capacities of both tubes. Whereas heat conduction in the metal tube is isotropic, heat conduction in the compound tube is anisotropic with a high conductivity along the outer surface and a low conductivity to the inside. This anisotropy and the cooling mechanism in the compound tube due to vaporising water are the reason for the high laser resistance of the tube. Paper received 13 June 1997; accepted after revision 16 February 1998.     

小儿腹腔镜疝内环扎术应用氯胺酮异丙酚复合静脉麻醉分析

目的　探讨氯胺酮异丙酚复合静脉麻醉用于小儿腹腔镜疝内环扎术的可行性、安全性、实用性。　方法40例行腹腔镜疝内环扎术患儿 ,随机分为全麻插管组 (A组 2 0例 )和非插管组 (B组 2 0例 ) ,连续监测HR、SBP、DBP、SPO2 ,分时段抽动脉血行血气分析。　结果　两组气腹时HR均增快 ,但无统计学意义 ,放气后逐渐恢复至气腹前水平。B组气腹后 10min ,PaCO2 、HCO3-均明显高于麻醉前 (P <0 .0 5 )但尚在正常范围 ,组间比较亦无明显差异 (P >0 .0 5 ) ;A组气腹后 10min ,PaO2 明显高于麻醉前及B组 (P <0 .0 5 )。　结论　氯胺酮异丙酚复合静脉麻醉在小儿腹腔镜疝内环扎手术中是一种可行的麻醉方法 ,但手术时间如大于 1h仍以气管内插管控制呼吸为宜     

气管内插管和置喉罩应激反应的比较

目的 比较在麻醉诱导后气管内插管和置喉罩对病人的心血管反应和肾素—血管紧张素浓度的变化。方法 选择无心血管疾病 ,ASAI～II级 ,择期全麻手术患者40例 ,按投币法随机分成两组—气管内插管组(T组)和置喉罩组(L组) ,每组20例。气管内插管用喉镜明视插入法 ,喉罩按顺行盲探置入口底。全部病人均于诱导前 (t0)、气管内插管或置喉罩后即刻(t1)、1min(t2)、3min(t3)、5min(t4)测SBP、SDP、HR以及经颈内静脉采血标本2ML。血标本用放射免疫法测血管紧张素II(ATII)浓度、血管紧张素I(ATI)浓度时间变化率。结果 麻醉诱导后SBP、SDP、HR均下降(p<0.05) ,插管或置喉罩后即刻与1min两组比较有显著性意义 ,T组高于L组(p<0.05)。插管或置喉罩后ATII、ATI变化两组比较差别有显著性意义(p<0.05) ,且T组高于L组。结论 置喉罩对病人的应激反应小