Late complications of tracheotomy

Complications of tracheotomy are largely preventable. Although some authors cite these complications as indications for prolonged endotracheal intubation to avoid tracheotomy, others believe that the laryngotracheal complications of prolonged endotracheal intubation warrant early tracheotomy. Obviously, unnecessary tracheotomies should not be performed, and the controversy regarding the timing of conversion of endotracheal intubation to tracheotomy is handled in an earlier article in this issue. We feel, however, that a properly performed tracheotomy has a low incidence of complications that are more easily managed than are the complex laryngotracheal complications of prolonged endotracheal intubation. Significant post-tracheotomy tracheal stenosis occurs in 8% of patients and is secondary to an overly large tracheotomy stoma or damage at the tracheostomy tube cuff site. Stoma stenosis can be minimized by not making an overly large tracheal stoma and by prevention of undue leverage on the tracheostomy tube. Cuff stenosis can be minimized by the use of the high-volume low-pressure cuffs with careful prevention of overdistention of the cuff. Bronchoscopic dilatation, laser resection, and Silastic T-tube placement provide control of the airway until definitive surgical resection and reconstruction can be performed safely. Tracheoesophageal fistula is an uncommon but life-threatening complication that can be prevented by avoiding overdistention of the tracheostomy tube cuff and by avoiding the concomitant use of a stiff nasogastric tube. These patients are best managed conservatively until they are able to be weaned from a ventilator. A single-stage repair of both the esophagus and the trachea should then be done. Tracheoinnominate artery fistula can be avoided by correct placement of the tracheostomy stoma through the second and third tracheal rings rather than lower in the trachea and by avoidance of overinflation of tracheostomy tube cuffs.     

Reduction in tracheal lumen due to endotracheal intubation and its calculated clinical significance

BACKGROUND: The flow in the human trachea is turbulent. Thus, the tracheal resistance (R) and the pressure gradient (DeltaP) required to maintain a given flow across the trachea is inversely related to its radius raised to the fifth power. If the caliber reduction ratio (X) after endotracheal intubation is calculated as X = radius of the endotracheal tube (rETT)/radius of the trachea (rT), then DeltaP and/or R will be increased by (1/X)(5). STUDY OBJECTIVES: To measure the actual ratio between rETT and rT following endotracheal intubation of pediatric patients with respiratory failure and to calculate the resulting increase in the tracheal R and DeltaP for a given inspiratory flow rate. DESIGN: Retrospective chart review. SETTING: Pediatric ICU in a tertiary-care teaching children's medical center. PATIENT ENROLLMENT: Twenty consecutive pediatric patients (mean [+/- SD] age, 6.4 +/- 7.2 years) whose tracheas had been intubated for various causes of respiratory failure, and who had received a CT scan, were included in our study. All patients received an endotracheal tube the size of which was derived from the following formula: (age in years/4) + 4. MEASUREMENTS AND MAIN RESULTS: rT and rETT were measured from CT scan sections at and around the level of the thoracic inlet, and the average values were used to calculate X. These values ranged from 0.33 to 0.65 (mean, 0. 55 +/- 0.8). The factor (1/X)(5) was calculated for each patient and then was multiplied by the known normal value for tracheal R for adolescents and adults (0.07 cm H(2)O/L/s) to obtain the value of R resulting from the artificial airway, (1/X)(5) x 0.07. Our results showed that tracheal R increased due to caliber reduction of the trachea after endotracheal intubation by 33.9 +/- 52.5-fold (range, 8.6- to 255.5-fold). In order to maintain an inspiratory flow of 1 L/s, the value of P for the intubated trachea would increase from 0. 07 cm H(2)O to a mean of 2.4 +/- 3.7 cm H(2)O (range, 0.6 to 18 cm H(2)O). In two of our patients, the rT/rETT ratios were < 0.5 (0.33 and 0.44, respectively); this translated into a more significant increase in the calculated DeltaPs, 18 and 4.2 cm H(2)O, respectively. CONCLUSIONS:: The common value of X due to endotracheal intubation is between 0.5 and 0.6, which in and of itself results in an increase in R across the intubated trachea up to 32-fold. The calculated increase in P as a result of this is between 2 and 3 cm H(2)O for adolescents or young adults. The addition of pressure support of at least 3 cm H(2)O during spontaneous ventilation via an endotracheal tube, which is common practice in pediatric critical care, should alleviate any respiratory distress emanating from the increased R. However, a value for X < 0.5, which was found in 10% of our patients (2 of 20 patients), results in a much higher calculated increase in the pressure gradient and, therefore, a higher level of pressure support is required to overcome this increase.     

Intracuff pressures in endotracheal and tracheostomy tubes. Related cuff physical characteristics

This study compared intracuff pressure (ICP) during mechanical ventilation in a variety of currently used endotracheal (ET) and tracheostomy (trach) tube cuffs and related cuff physical characteristics. Tracheostomy tube physical characteristics were also measured. Variation was observed to exist between "just-seal" inspiratory and end-expiratory intracuff pressure during mechanical ventilation. Cuff diameter, thickness, compliance, geometry (shape), resting volume, and just-seal volume also varied. ICP varied with cuff diameter, thickness, compliance, geometry (shape), and trachea size, as well as tube curve and cuff position in the trachea. Thin, large-diameter, compliant cuffs generally "just seal" with relatively low ICPs. We recommend use of tracheal airways (endotracheal and tracheostomy) fitted with cuffs that seal in patients with low intracuff pressures. We also recommend nonrigid (soft) thermolabile tracheostomy tubes.     

The effect of a gas leak around the endotracheal tube on the mean tracheal pressure during mechanical ventilation

Infants requiring mechanical ventilation are usually intubated with uncuffed endotracheal tubes, which permit gas to leak between the tube and the trachea. This gas leak may alter the mean pressure transmitted to the trachea by changing the pattern of airway flow and modifying the resistive behavior of the endotracheal tube. To test this hypothesis, we measured mean tracheal pressure, gas flow through the endotracheal tube, and resistance of the tube in rabbits ventilated with and without a leak. We also studied the effect of the tube size and the pattern of ventilation on these measurements. We found that a leak reduced the mean tracheal pressure by 15 to 21% with respect to the mean proximal airway pressure. This reduction was caused by an increased difference between inspiratory and expiratory flow through the endotracheal tube, and by the mean expiratory resistance of the tube being lower than its mean inspiratory resistance. The rabbits with smaller tubes had lower mean tracheal pressures. A ventilatory pattern of short inspiratory times and high peak pressures was associated with a proportionally greater decrease in mean tracheal pressure caused by the leak. These findings suggest that the mean proximal airway pressure, measured at the ventilator, may overestimate the mean tracheal pressure in the presence of a gas leak around the tube. Furthermore, the decrease in mean tracheal pressure caused by the leak may decrease oxygenation despite a constant mean proximal airway pressure.     

机械通气时气管套管致气管食管瘘的原因分析和预防措施探讨

目的探讨机械通气患者气管切开套管引起气管食管瘘的原因及其预防措施。方法结合5例气管切开套管导致气管食管瘘的机械通气患者临床资料和相关文献复习,详细分析其病因和预防措施。结果机械通气患者发生气管食管瘘与气囊压力过高、气囊压迫时间过长、呼吸机管道重力压迫气管后壁、套管不稳定活动增多、气管切开破坏了气管的结构和稳定性等因素有关,预防措施主要是常规监测气囊内压、避免压力过高、妥善固定气管套管、减轻呼吸机管道对气管后壁的压迫、躁动病人适当镇静等。结论加强机械通气患者人工气道与气囊的管理,能最大限度减轻气管内膜机械性损伤,降低气管食管瘘的发生率。     

Tracheal rupture and the creation of a false passage after emergency intubation

Endotracheal intubation is a common emergency department procedure with rare but potentially life-threatening complications. A systematic review of the literature demonstrated that all patients with traumatic tracheal rupture after endotracheal intubation could be adequately ventilated despite tracheal perforation. We report an unusual case of tracheal perforation in which the patient could not be effectively ventilated because of the creation of a false passage caused by the endotracheal tube adjacent to the posterior wall of the trachea.     

The effectiveness of hourly cuff deflation in minimizing tracheal damage.

The efficacy of hourly endotracheal tube cuff deflations in minimizing tracheal damage has not been clearly established. Two investigations which specifically address this question arrive at differing conclusions. These investigations fail to report important variables which may have explained the difference in their results. The present study examined the effects of hourly cuff deflations in minimizing tracheal damage in mechanically ventilated, anesthetized dogs over a 72 hour test period. Variables which may influence tracheal damage were measured and reported. Three groups of dogs received either continuous cuff inflation, hourly 5 minute cuff deflations, or a continuous air leak. The air leak group had significanlty less damage than the continuous inflation group (P less than 0.05) and the hourly deflation group (P less than 0.01). There was no significant difference between the continuous inflation group and the 5 minute hourly deflation group.     

Tracheal tear and tension pneumothorax complicating bronchoscopy-guided percutaneous tracheostomy

Percutaneous dilatational tracheostomy (PDT) is a frequently conducted procedure in critically ill patients. Bronchoscopic guidance of PDT is generally recommended to minimize the risk of unintentional tracheal injury. We present a case of tracheal tear and tension pneumothorax, a rare but potentially life-threatening complication, during continuously bronchoscopy-guided PDT. Sealing the large tracheal air fistula with the cuff of an endotracheal tube helped bridge time to definitive surgical repair in our patient. Bronchoscopic guidance may minimize, but cannot completely eliminate, the risk of tracheal injury during PDT.     

Dumon stent placement via endotracheal tube]

We conducted a Dumon stent placement via endotracheal tube for 10 patients with airway stenosis. The conventional endotracheal tube is inserted beyond the stenosis site; this procedure is conducted with the use of a flexible bronchoscope under general anesthesia. The Dumon stent is folded and inserted into the endotracheal tube and is then introduced into the stenosis site with the use of a cylindrical-tipped stainless steel wire as a pusher. Although the Dumon stents were placed using a rigid bronchoscope for the first 7 patients, the present procedure was used for the latest 10 patients. Compared with the rigid bronchoscope technique, this procedure is suitable for the placement of a larger stent for a shorter time. It has the following advantages over the rigid bronchoscope technique: (1) the use of an endotracheal tube and flexible bronchoscope makes the stent placement easier for the practitioner and less stressful for the patient; (2) because of the flexibility of the endotracheal tube, a Dumon stent can be placed easily, even in the left main bronchus or in a markedly shifted trachea or bronchus, and also in a patient who has difficulty in expanding the neck; (3) a stent can be placed safely in a patient with severe tracheal stenosis and orthopnea. The present procedure does, however, have the disadvantage that it is difficult to control the direction of the tip of the endotracheal tube. We concluded that the present procedure could be a useful method for Dumon stent placement.     

Postextubation Obstructive Pseudomembranes: A Case Series and Review of a Rare Complication After Endotracheal Intubation

Endotracheal intubation obviously may be life-saving, but it may also lead to complications, including those related to damage of the airways. Superficial damage of the trachea at the site of the endotracheal cuff may trigger the formation of an obstructive fibrinous tracheal pseudomembrane (OFTP). Shortly after extubation, this clot, consisting of fibrin, leucocytes, and necrotic epithelium, can cause stridor due to adherence to the tracheal wall and obstruction of the airway. In most cases, the lesion is easily removed by rigid or fiberoptic bronchoscopy and virtually never leads to permanent damage. The study consisted of case series and review of the literature. This report describes a series of five adult cases and reviews all 19 other previously described cases. A careful analysis of all reported cases, however, did not highlight a simple predisposing factor or illness. It is important to consider OFTP in the differential diagnosis of stridor and respiratory insufficiency in the postextubation period.     

Iatrogenic pulmonary overpressure accident

An unconscious victim of an overdose was intubated with an endotracheal tube to prevent aspiration. The respiratory therapist deflated the cuff of the endotracheal tube to allow for a retrograde oral air leak and then tightly attached the oxygen tube directly to the endotracheal tube. Seconds later there was a loud pop as the oxygen tube blew off the end of the endotracheal tube. The patient sustained both a hemodynamic and a neurologic decompensation as the result of marked pulmonary overinflation, with bilateral pneumothoraces and probable cerebral and coronary artery air emboli. We present the case in the hope that it will help avoid any such future occurrences.     

Differential effects of continuous versus intermittent suction on tracheal tissue

The purpose of this study was to determine the differential effect of continuous versus intermittent application of negative pressure on tracheal tissue during endotracheal suctioning. The sample consisted of 12 mongrel dogs, randomly assigned to group 1 (N = 5), continuous suction, or group 2 (N = 5), intermittent suction. All animals were orally intubated (40F endotracheal tube). Two control animals were intubated and not suctioned. Animals in group 1 and 2 were suctioned every 15 minutes for 4 hours for a total of 16 suction passes. Endotracheal suctioning was performed by using a 14F suction catheter either continuously (10 seconds) or intermittently (2 seconds with, 1 second without for a total of 10 seconds) at a suction pressure of 200 mm Hg and a suction flow rate of 16 L/min. Tracheal tissue samples were examined for simplified and major simplified damage, ulceration, and ulceration with necrosis. Results indicated that all forms of damage were present with both suctioning techniques. No significant differences were found between group 1 and group 2 (Wilcoxon rank sum) for any of the alterations. Results indicate that both continuous and intermittent application of negative pressure with endotracheal suction produces significant damage to tracheal tissue.     

Percutaneous transtracheal jet ventilation: a safe, quick, and temporary way to provide oxygenation and ventilation when conventional methods are unsuccessful

INTRODUCTION: Percutaneous transtracheal jet ventilation (PTJV) with a large-bore angiocath that is inserted through the cricothyroid membrane can provide immediate oxygenation from a high-pressure (50 lb per square inch) oxygen wall outlet, as well as ventilation by means of manual triggering. The objective of this retrospective study is to highlight the potential benefit of PTJV as a temporary lifesaving procedure during difficult situations when oral endotracheal intubation is unsuccessful and bag-valve-mask ventilation is ineffective for oxygenation during acute respiratory failure. METHODS: The medical records of 29 consecutive patients who required emergent PTJV within the past 4 years were reviewed. PTJV was required because the pulse O(2) saturation could not be maintained at > 90% with bag-mask-valve ventilation and because the airway could not be secured quickly with direct laryngoscopy. RESULTS: The cricothyroid membrane was cannulated successfully in 23 patients. In these patients, pulse O(2) saturation was raised to > 90% and was maintained with PTJV until the airway was secured. All but 3 of the 23 patients were subsequently intubated orally. In one patient, PTJV maintained adequate gas exchange until an emergent tracheostomy was performed. In two patients, airway exchange catheters were inserted into the trachea due to a small glottic aperture. The endotracheal tube was slid over the catheter. In 6 of the 29 patients, there was difficulty inserting a catheter through the cricothyroid membrane or there was inability to insufflate the oxygen with a jet ventilator. There were no immediate fatalities from the use of PTJV. CONCLUSION: Based on the subsequent insertion of an endotracheal tube into the trachea, there were two important benefits in the patients who underwent PTJV successfully. First, PTJV provided effective oxygenation, while allowing adequate time for upper airway visualization and possible suctioning of oropharyngeal secretions. Second, tracheal intubation was subsequently easier, possibly because the high tracheal pressure from the gas insufflation opened the collapsed glottis, making visualization of the glottic aperture better. PTJV is safe and quick in providing immediate oxygenation, and therefore should be considered as an alternative to insistent, multiple intubation attempts, when neither bag-mask-valve ventilation nor endotracheal intubation is feasible in providing adequate gas exchange.     

常规密闭机械通气在全麻下支气管镜介入治疗中的应用研究

目的 通过经气管插管对常规密闭机械通气的健康犬施行支气管镜模拟介入治疗,观察气管镜插入前后呼吸机参数及动脉血气分析的变化情况,以期寻求在常规密闭机械通气的条件下实施支气管镜介入治疗时所需要的适宜的气管通道及呼吸机参数.方法 健康杂种犬10只,全麻和肌松状态下气管插管、常规密闭机械通气,稳定后将直径6.0 mm的支气管镜...     

Endotracheal tube exchangers: should we look for safer alternatives?

Endotracheal tube exchange is considered a simple procedure, performed in cases of endotracheal tube malfunction. It usually involves the use of airway exchange catheters (AECs). The procedure, however, can lead to major complications that require prompt intervention for optimal outcomes. We report on a case of endotracheal tube exchange with AECs complicated by pneumothorax, without evidence of tracheal or bronchial injury demonstrable via bronchoscopy. Increasing rates of AEC-related complications highlight the need for alternative methods to exchange malfunctioning endotracheal tubes safely.     

Massive tracheal necrosis complicating endotracheal intubation

There are significant complications associated with endotracheal intubation. Massive tracheal necrosis secondary to tracheoesophageal space abscess developed in a 71-year-old man during mechanical ventilation. Elevated endotracheal tube cuff pressures, sepsis, hypotension, and other risk factors predispose to this disastrous consequence.     

The esophageal detector device: a rapid and accurate method for assessing tracheal versus esophageal intubation in a porcine model.

STUDY OBJECTIVES: To assess time and accuracy of the esophageal detector device (EDD), disposable end-tidal CO2 monitor (ETCO2), and standard clinical methods for detection of endotracheal tube placement. DESIGN: Prospective, randomized, single-blinded, controlled laboratory investigation. METHODS: Thirty airway managers (physicians, nurse anesthetists, and paramedics) used one pig (Sus scrofa) as the intubated, respiratory depressed/arrest model. INTERVENTIONS: Part 1: A standard 7.5-mm endotracheal tube was placed in either the esophagus or the trachea of the anesthetized swine. Anatomic location was verified by bronchoscopy. Airway managers blinded to the endotracheal tube location were assigned randomly to identify tube position by one of three methods (EDD, ETCO2, or clinical methods). Speed and accuracy of the assessment were recorded. Part 2: A second identical tube was placed, so that both the esophagus and the trachea were intubated; then, the esophageal tube was bag-ventilated for one minute. Each blinded airway manager, using only the EDD, determined placement site of both tubes. RESULTS: Part 1: Mean time to determine tube placement for group A (EDD) was 13.8 seconds; group B (ETCO2), 31.5 seconds; and group C (clinical methods), 39 seconds. Comparison by analysis of variance yielded a value of P less than .001. Both groups A and B were 100% accurate, whereas 30% of the subjects from group C mistakenly assessed an esophageal tube as in the trachea. Part 2: The EDD remained 100% sensitive and specific despite prior ventilation of the esophageal tube. CONCLUSION: In this porcine model, the EDD and ETCO2 were more accurate than clinical methods in determining endotracheal tube placement. The EDD demonstrated a significant time advantage over both ETCO2 and clinical methods. Prior ventilation of the esophageal tube does not interfere with the accuracy of the EDD.     

Effect of cuffed endotracheal tubes on tracheal mucous velocity.

The inflated cuffed endotracheal tube produces a significant depression of tracheal mucous velocity in anesthetized dogs after one hour. This effect occurs with bot low and high compliance cuffs but is not observed with an uncuffed tube. This phenomenon is another factor that must be considered in establishing criteria for the frequency of cuff deflation in patients supported by mechanical ventilators.     

Reflex influences from the extrathoracic trachea during airway occlusion.

We have performed experiments in 26 dogs anesthetized with pentobarbital and fitted with an endotracheal tube. The inflatable cuff of this tube was positioned either at the level of the cricoid cartilage or at the thoracic inlet. In this latter situation the extrathoracic trachea (E.T.T.) is not subjected to any change in transmural pressure both during breathing and airway occlusion. We have compared the inspiratory output in term of the integrated phrenic discharge during airway occlusion at FRC with the tracheal tube positioned at either one of the two levels. In most of the experiments (16 out of 26) the inspiratory output during airway occlusion is significantly greater (157%) when the E.T.T. is not by-passed and this difference disappears after bilateral vagotomy. We interpret these results by the asymmetrical response of the tracheal stretch receptors to positive and negative transmural pressure (Pt); most of these receptors are active at FRC and decrease their activity at low negative Pt, as that attained in the first occluded breath. These results seem to suggest that the reflex influences from the extrathoracic tracheal receptors on the inspiratory output are similar to those originating from the intrathoracic airway stretch receptors.     

Nontypable Haemophilus influenzae nosocomial pulmonary infections in children following intubation

Twenty-nine intubated pediatric patients were prospectively studied to determine whether nontypable Haemophilus influenzae (NTHI) is associated with the development of nosocomial pneumonia. Throat cultures and tracheal Gram stains, leukocyte counts and cultures were obtained immediately following intubation, then serial studies on tracheal secretions were performed. Median patient age was 13 months. One patient had preexisting lung disease and 14 (48%) had pneumonia when intubated. There were five deaths. NTHI was recovered from the initial throat or tracheal culture in seven patients (24%); none developed a nosocomial lower respiratory tract infection. NTHI was not associated with any of three cases of nosocomial pneumonia. Three of 12 NTHI isolates were beta-lactamase producers. Tracheal leukocyte counts and Gram stains were not predictive of pneumonia, either at the time of intubation or subsequently. We conclude that NTHI in the oropharynx or trachea is not predictive of pneumonia among intubated pediatric patients.