Tracheal intubation

Tracheal intubation is the act of placing a tube into the trachea. The tube enables oxygen delivery and removal of carbon dioxide, while also allowing for the administration of pharmacological agents. Intubation is the most reliable method of maintaining an airway under anaesthesia, and for protection against aspiration of stomach contents. Traditionally, intubation is achieved by direct visualization of the glottis, but now indirect laryngoscopy (via a videolaryngoscope) is a common alternative. Prior to embarking upon intubation, a thorough patient history and examination must be undertaken by the laryngoscopist; equipment must be prepared and checked; a trained assistant present; and an experienced anaesthetist available in case assistance is required. Once the endotracheal tube has been placed, correct positioning must be confirmed via both clinical examination and monitoring, including capnography. Tracheal intubation is a procedure that should only be undertaken by trained operators and is not without risk. It is important to note that it is failure to oxygenate patients rather than failure to intubate that ultimately leads to serious morbidity and mortality. The Difficult Airway Society has produced guidelines on how to manage unanticipated difficulty in tracheal intubation; it is essential that every practitioner trained to intubate patients is familiar with these algorithms and the key principles of safe airway management.     

Design and Performance of Blanket Heat Shields for Neonates

ABSTRACT. Background: Several designs of plastic blanket heat shields are in use. This study was done to compare different designs for their efficiency in reducing heat loss. Methods: Four heat shield designs were tested by sequentially covering each of 14 infants (wt. 640–2030 g) cared for under radiant warmers. The power consumption of the radiant warmers was measured as a surrogate for. heat loss. All designs were tested for a total of 20 min on all infants. Results were calculated as percent change in power consumption from shield to shield. The most efficient design was further modified and evaluated in another group of 14 infants (wt. 700–1180 g). Results: The relative reductions in power consumption were: no shield (control) –0%, a plastic foil over the side rails: –17%, a single layer close to the infant but excluding the head: –34%, the same as double layer –37% and the most efficient one, a single layer covering the whole infant –42%. A modification of this design, tested in the second group of infants, reduced power consumption by 13% (95% CI –5.9/–19.7), ( p < 0.004) when compared to the single layer covering the whole infant. It was tucked under the connecting tubes to the ventilator. It also reduced the risk for displacement and allowed for the endotracheal tube to be suctioned without removing the blanket. Conclusion: Modifications of the design of heat shield blankets for infants resulted in significant increases in efficiency.     

Difficulties with tooth protectors in endotracheal intubation

The suitability of three tooth protectors for routine use during endotracheal intubation was studied in 300 consecutive patients undergoing elective operations under general anaesthesia. The main disadvantages of the protectors were lack of space and the consequent difficulty of guiding the endotracheal tube into the larynx, and poor visibility, especially when the Camo protector was used. These difficulties could be avoided in most cases by cutting off the right angle of the Camo protector. The less experienced anaesthesiologists especially had difficulties with the protectors: 20% of patients in the Camo group were considered impossible to intubate unless the protector was removed. The silicone inlay of the Camo protector melts and becomes adhesive at body temperature, which makes its prolonged use hazardous. Two patients lost a maxillary incisor despite the proper use of a protector (Denex). Thus the use of a tooth protector alone does not guarantee avoidance of dental trauma. Better results could be obtained by improving the design of the protectors and by careful pre-anaesthetic dental examination.     

Endotracheal suctioning causes right upper lobe collapse in intubated children

Objective: Right upper lobe collapse is a common radiographic finding in intubated children. We hypothesized that deep suctioning and uncontrolled negative pressures during endotracheal tube suctioning were significant contributory factors. Methods : The incidence of right upper lobe (RUL) collapse in intubated, ventilated children on a paediatric cardiac intensive care unit was determined over a 3-month period ( n = 102). Graduated suction catheters and suction vacuums of < 165 cm H₂O were then introduced. Another prospective audit was carried out 3 months later ( n = 60). Results : We found that 24% developed RUL collapse and 4 developed an apical pneumothorax. Following the introduction of graduated catheters and controlled vacuums pressures, a significant reduction in the incidence of RUL collapse, to 7%, was observed ( p < 0.05). Conclusions : We conclude that high negative pressure and deep-suctioning causes RUL collapse in children. Any lobar collapse not only prolongs the child's stay in intensive care, but can be associated with further morbidity which may have a serious implication. By improving suctioning technique this morbidity can be significantly reduced.     

An armoured endotracheal tube obstruction in a child

The case of a child whose tracheal tube became obstructed intraoperatively 30 minutes after intubation is reported. It appears that this obstruction was related to the development of bubbles within the walls which expanded upon exposure to nitrous oxide and diffusion of that gas into the bubbles. The authors want to point out the risk of gas diffusion into the walls of the tube and the possibility that repeated sterilization may enhance the development of bubbles. Les auteurs rapportent l’observation d’un enfant de sept mois dont la sonde tracheale s’est obstruée 30 minutes après l’intubation. Cette obstruction était due à l’expansion de bulles incluses dans la paroi du tube après exposition au N₂O et diffusion de celui-ci à l’interieur des bulles. Ils accusent également la stérilisation répétée de la sonde armée (contre l’avis du constructeur) d’avoir favorisé le développement de ces inclusions bulleuses.     

困难气管内插管的预测和处理

目的 探讨对困难气管内插管的预测及处理方法。方法 随机选取各类需行气管内插管麻醉下择期手术患者50例,术前测量IG、Slux,TM,HENE,HFNF、气道分类及声门分级等各项指标,并分析它们在气管插管难度之间的关系。结果 50例患者中,气道分类Ⅳ类者7例,声门分级Ⅲ级者17例,Ⅳ级者1例。17例声门Ⅲ级者以EtCO2引导下口腔盲插法插管成功,1例声门Ⅳ级者以气囊充气鼻腔盲控气管内插管法插管成功。结论 术前评价气管插管难易程度应综合考察各项测量指标,这些指标中又以声门分级最为可靠。     

Monitoring normal and aberrant electrocardiographic activity from an endotracheal tube: Comparison of the surface,esophageal, and tracheal electrocardiograms

Introduction. We designed an endotracheal (ET) tube with orthogonally spaced ECG cuff electrodes. This ET tube was evaluated in dogs and sheep to determine (1) whether ECGs recorded from our tube were sufficient to make accurate clinical decisions concerning heart rate and rhythm; and (2) whether metallic cuff electrodes in direct contact with the trachea could induce mucosal burn injury during episodes of defibrillation.Methods. Using experimental animals, we obtained ECGs from their tracheae and compared our findings with ECGs obtained from surface and esophageal electrodes. The electrical activity of the heart was modified by increasing the depth of anesthesia, occluding the left coronary artery, and administering beta-adrenergic drugs. Before the dogs were euthanized, they were subjected to episodes of transthoracic and intrathoracic defibrillation at energy levels of 200 to 400 J. A postmortem pathological examination of the trachea was performed to determine the incidence of mucosal burn injury.Results. Tracheal electrocardiography provided valid information on heart-rate monitoring and certain morphology profiles. The R-R, PR, QRS, and QT intervals measured from the trachea had a correlation of 1.0, 0.96, 0.83, and 0.98, respectively, when compared with the same intervals obtained from surface electrodes. Two tracheae subjected to intrathoracic defibrillation at >300 J revealed evidence of minor burn injury. Some localized epithelium loss was displayed in all tracheae; we attributed this to tracheal intubation.Conclusion. Tracheal electrocardiography may be useful in trauma patients who require intubation where injury precludes placement of chest ECG electrodes.     

A literature review of the prehospital use of neuromuscular blocking agents by air medical personnel to facilitate endotracheal intubation

Air medical personnel in the United States have used neuromuscular blocking agents to facilitate endotracheal intubation in the field for more than a decade. This literature review examines 15 studies to investigate their experience and explores the following specific areas: the intubation success rate in patients who did or did not receive these agents, the intubation success rate of air medical personnel before and after they incorporated these agents into their practice, the neuromuscular blocking agents and adjunct medications used by air medical personnel, and the disposition of patients who could not be intubated after an agent was given. The data suggest that, overall, air medical personnel use these agents safely and effectively. Suggestions are offered for future studies, including examining ground time when agents are used to facilitate intubation, complications of their use in this setting, and the use of simulators to train personnel in the administration of these medications.     

气管导管位置检测仪的研制

利用Hall传感器设计了一个气管导管位置检测仪来快速检测气管导管的位置.气管插管时,Hall传感器探头固定在病人颈部皮肤上,顶端带有小磁铁的管芯随气管导管一起进入气管中,根据检测到的磁场强度的大小,测量出探头与磁铁间的距离,从而判断出气管导管的位置.经临床测试,该检测仪性能可靠,测量准确,可以用于教学及临床气管插管时气管导管的定位.