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.     

High frequency oscillatory ventilation in children: an overview

The last 30 years, high frequency ventilation (HFV) has found its way from the neonatal to the paediatric and adult ICU. With its small tidal volumes, strict intrathoracic pressure variations and disengagement of ventilation from oxygenation, HFV fits in our insights nowadays in lung protective ventilation. This review provides you with an understanding of the different modes of HFV, gas exchange mechanisms during HFV which uses tidal volumes below dead space volume, and some information on nursing and weaning a child on HFV. Focus will be on the clinical use of high frequency oscillatory ventilation with a practical overview of the strategies used: the high-volume strategy designed to rapidly recruit and maintain optimal lung volume in diffuse alveolar disease and lung haemorrhage, the low volume strategy in airleak, and the open airway strategy in small airway disease where the continuous distending pressure is used to recruit and stent the airways.     

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.     

Unilateral pulmonary oedema due to lung re-expansion following pleurocentesis for spontaneous pneumothorax. The role of non-invasive continuous positive airway pressure ventilation

Re-expansion pulmonary oedema represents a rare complication of treatment of spontaneous pneumothorax with only a few cases documented in the current literature. We present the case of a 47-year-old male who presented a right-sided spontaneous pneumothorax and developed respiratory failure after chest tube drainage. The diagnosis of re-expansion pulmonary oedema was made and he was successfully treated with non-invasive continuous positive airway pressure ventilation. Since pathogenesis of re-expansion unilateral pulmonary oedema differs significantly from that of cardiogenic pulmonary oedema, the role of non-invasive continuous positive airway pressure ventilation is discussed as an additional therapeutic option.     

Recurrent pneumothoraces associated with nocturnal noninvasive ventilation in a patient with muscular dystrophy

Although a common complication of mechanical ventilation in acute respiratory failure, spontaneous pneumothorax has been rarely reported among patients on chronic, intermittent, noninvasive positive pressure support. We report the first case of recurrent pneumothoraces associated with nocturnal bilevel positive airway pressure ventilation via a nasal mask.A 26-year old man with chronic respiratory failure secondary to an unclassified neuromuscular condition suffered four separate episodes of spontaneous pneumothorax over a 12-month period. Two episodes occurred while he was asleep on bilevel positive airway pressure support. He was found to have numerous subpleural blebs, and we propose a mechanism for their development. Following open pleurodesis and blebectomy, the patient has not had another pneumothorax.Given the increasing utilization of chronic nocturnal bilevel positive airway pressure ventilation, we suggest that healthcare providers and patients be made aware of this potentially life-threatening complication.     

Novel in-vitro model to study first responses of airway epithelial cells to allergen and pro-inflammatory stimuli at birth

BackgroundThe airway epithelium is increasingly being implicated in the pathogenesis of asthma. Although believed to be important, little is known about how the neonatal airway epithelial cell (AEC) phenotype impacts on respiratory disease in later life. The aim of this study was to establish a methodology for culturing neonatal nasal AEC and to describe AEC response in vitro.MethodsAECs were sampled from healthy, unsedated infants during the first week of life by brushing both nostrils with an interdental brush. Sampled AECs were used for cytospin preparation or grown to confluence before subculture. Cultured cells were characterised morphologically and by immunocytochemistry. Interleukin-8 concentrations were measured in supernatants from monolayers at rest and after exposure to concentration ranges of interleukin 1β and tumour necrosis factor α or house dust mite extract.FindingsPrimary cultures were successfully established in 109 (92%) of 117 neonates sampled, with 93 (80%) successfully cultured to confluence at third passage. The epithelial lineage of the cells was confirmed by morphological analysis and immunocytochemistry. Constitutive interleukin-8 secretion was observed and was upregulated by both stimuli in a dose dependent manner.InterpretationWe describe a safe, minimally invasive method of culturing AECs from neonates suitable for functional cell analysis and amenable to large population based studies. This novel technique offers a unique opportunity to study naive AECs not yet exposed to the modifying effects of environmental pollutants and viral pathogens and may prove useful in elucidating the early origins of asthma.FundingChief Scientist Office of the Scottish Government.     

机械通气中气道压力增高的原因与防治

目的探讨机械通气患者气道压力增高的原因与防治对策。方法对本科2000年1月～2005年8月收治的112例机械通气病例进行回顾性分析。结果发生气道压力增高49例。其原因包括:气道阻塞31例,支气管痉挛7例,肺水肿5例,单肺通气3例,导管受压2例,气胸1例。结论气道阻塞、支气管痉挛、肺水肿为气道压力增高的主要原因。综合防治措施,可防止气道压力增高的发生,提高救治存活率。     

香烟烟雾提取物对动物气道上皮细胞E钙粘着蛋白表达的影响

目的观察香烟烟雾提取物（ＣＳＥ）对气道上皮细胞（ＡＥＣ）、上皮钙粘附素（ＥＣＤ）表达的影响,探讨其表达变化在吸烟致ＡＥＣ损伤中的作用。方法体外培养小鼠气管环及猪ＡＥＣ,加入一定浓度的ＣＳＥ,应用免疫组化染色和图像分析法检测ＡＥＣ中ＥＣＤ表达的变化。结果正常ＡＥＣ中ＥＣＤ表达于相邻上皮细胞连接处的胞膜上,２０％ＣＳＥ作用１２和２４小时后,膜上ＥＣＤ表达减少,胞浆内表达量分别为正常对照组的１６１和１３２倍（Ｐ均＜００１）,且２４小时表达量为１２小时的１２１倍（Ｐ＜００１）。结论ＣＳＥ使ＡＥＣ中ＥＣＤ膜上表达下调,胞浆内表达增高,该表达变化可能介导了吸烟对ＡＥＣ的损伤作用。     

Chronisch interstitielle Lungenerkrankungen

Acute exacerbation of interstitial pulmonary disease is characterized by a critical deterioration of gas exchange and respiration. In addition to exacerbation of the underlying disease, the causes of the clinical deterioration are primarily acute severe infections, acute pulmonary embolism and the occurrence of pneumothorax. The clinical picture is characterized by increasing respiratory insufficiency which necessitates mechanical respiratory support (non-invasive or invasive). The mortality of ventilated patients with acute deterioration of interstitial pulmonary disease is very high and ranges between 80 and 100 % so that the indications for mechanical respiratory support must be viewed critically. The conditions and performance of mechanical ventilation depend very much on the individual pathophysiological situation and represent a great challenge for intensive care physicians.     

Cardiorespiratory effects of conventional and high frequency ventilation in rabbits with bilateral pneumothoraces and surfactant depleted lungs

We compared high frequency ventilation (HFV) to conventional mechanical ventilation (CMV) under normoxic and normocapnic condition in surfactant depleted rabbits with bilateral pneumothoraces. We hypothesized that lower airway pressures would be required with HFV under these conditions. We applied CMV and HFV in 8 anaesthetized rabbits with a prototype ventilator at frequencies of 30, 100,200, and 300 cycles/min. A positive end-expiratory pressure (PEEP) just below the pressure sufficient to open the air leak from the pneumothoraces was applied at all frequencies. Airway pressures, gas exchange, heart rate, and mean arterial pressure were recorded. Peak airway pressure decreased significantly from 2.50 to 2.10 kPa when the frequency of ventilation was increased from 30 to 300 cycleshnin. There were no significant changes in mean airway pressure, P_ao2arterial pH, heart rate, and mean arterial pressure when HFV was compared to CMV. In conclusion, during HFV peak airway pressures measured at the mouth were decreased. Our ability to maintain adequate gas exchange in the face of ongoing pulmonary air leaks may reflect lower alveolar pressures. Pediatr Pulmonol. 1993; 16:354–357. © 1993 Wiley-Liss, Inc.     

Ventilation induced pneumothorax following resolved empyema

We report a case of pneumothorax as a result of positive pressure ventilation in a child previously treated for empyema. Three months following discharge for successful treatment of empyema our patient received a general anesthetic for an elective MRI of the brain for investigation of nystagmus. During recovery from the anesthetic he developed respiratory distress and was found to have a loculated pneumothorax. We propose that pleural fragility in childhood empyema possibly persists even after clinical resolution and in this case for up to 3 months. The complication of pneumothorax should be considered in all patients receiving positive pressure ventilation following resolved empyema.     

Treatment with Bi-PAP in patients with bilateral diaphragm paralysis

Two patients with bilateral diaphragmatic paralysis are described. The first case occurred secondary to open chest surgery; the second occurred in a polytraumatized patient. Both were successfully treated with intermittent bi-level positive airway pressure (Bi-PAP). Bilateral diaphragmatic paralysis can be related to a variety of processes, although idiopathic forms also occur. Diagnosis can be difficult and should involve a high level of clinical suspicion. Treatment and prognosis are determined by the underlying disease. Some cases may require the establishment of nighttime support ventilation. Techniques for non-invasive ventilatory assistance such as Bi-PAP can improve symptoms markedly and allow patients to live independently.     

Tension pneumoperitoneum associated with a pleural-peritoneal shunt.

The differential diagnosis of pneumoperitoneum is broad. We report a case of tension pneumoperitoneum in a patient on mechanical ventilation with initially unrecognized pneumothorax who had an indwelling pleural-peritoneal shunt. The patient developed ventilatory and hemodynamic collapse as air was diverted from the pleural space into the peritoneal cavity. Subsequent abdominal exploration revealed the source of the intra-abdominal air. Placement of a chest thoracostomy tube and removal of the pleural-peritoneal catheter resulted in significant clinical improvement. We suggest that it is important to recognize that pleural-peritoneal catheters may cause tension pneumoperitoneum without obvious concurrent pneumothorax.     

Barotrauma and hypotension resulting from jet ventilation in critically ill patients

We present the first reports of pneumoperitoneum secondary to jet ventilation, barotrauma secondary to jet ventilation through the suction port of a fiberoptic laryngoscope, and hypotension due to jet ventilation via nasotracheal and orotracheal catheters. We suggest that minimizing airway pressure and using jet catheters with side holes may help decrease the risk of such complications. We cannot, at present, recommend the use of hand-held jet ventilators unless both adequate exhalation space is guaranteed and direct impingement of the catheter's tip on the mucosal surface is avoided.     

Elevated lung volume and alveolar pressure during jet ventilation of rabbits

We measured lung volume, tidal volume, and pressures at the airway opening, trachea, and alveoli during jet ventilation of rabbits at frequencies from 2 to 15 Hz when inspiratory time was varied from 10 to 50% of the ventilator cycle. Lung volume was determined dynamically and was dependent on tidal volume, expiratory duration, and the expiratory time constant of the respiratory system. Tidal volume decreased with increasing frequency and lung volume, and was greater than estimated dead-space volume over most of the frequency range studied. Pressure at the airway opening was not a good estimate of either mean pressure or pressure swings in the alveoli. Tracheal pressure corresponded fairly well to alveolar pressure. Alveolar pressure swings diminished with increasing frequency and decreasing inspiratory duration. In the clinical setting these results mean that measurement of pressures at the airway opening is not an adequate way to monitor patients during jet ventilation. In addition, the clinician must be aware that substantial increases in functional residual capacity may occur during jet ventilation, thereby placing the patient at risk of pneumothorax.     

Idiopathic pulmonary fibrosis: a disorder of epithelial cell dysfunction

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive dyspnea, interstitial infiltrates in lung parenchyma and restriction on pulmonary function testing. IPF is the most common and severe of the idiopathic interstitial pneumonias, with most individuals progressing to respiratory failure. Multiple lines of evidence reveal prominent roles for alveolar epithelial cells (AECs) in disease. The current disease paradigm is that ongoing or repetitive injurious stimuli in the presence of a genetic or acquired dysfunctional type II AEC phenotype results in increased AEC injury/apoptosis, deficiencies in regeneration of normal alveolar structure and aberrant lung repair and fibroblast activation, leading to progressive fibrosis. Although the nature of injurious events and processes involved in aberrant repair of the alveolar epithelium are not well understood, ongoing investigations provide hope to better understand mechanisms by which AECs maintain homeostasis or contribute to fibrosis. These strategies may hold promise for developing novel treatment approaches for IPF.     

A comparison of proximal and distal high-frequency jet ventilation in an experimental animal model

High-frequency jet ventilation using either a proximal or a distal endotracheal injection site through a triple-lumen endotracheal tube was studied in 10 adult cats. The comparative effects on pulmonary gas exchange, tracheal pressure, heart rate, and blood pressure were examined for each injection site at both high (8-12 pounds per square inch [PSI] and low (5-8 PSI) jet-driving pressures in normal and lung-injured cats. Lung injury was created by modification of a surfactant washout technique previously demonstrated in rabbits. Alveolar ventilation (PaCO2) was found to be significantly better with distal than with proximal jet injection under all experimental conditions. At high jet-driving pressures, peak inspiratory pressure was higher in both normal (p = 0.03) and lung-injured cats (p = 0.002) with distal high-frequency jet ventilation. In addition, lung-injured animals were observed to have higher distal mean airway pressures at high jet-driving pressures (p less than 0.01). No differences in oxygenation were found in any circumstances. The results of this animal study suggest that distal high-frequency jet ventilation may be more effective in those situations in which improvement in alveolar ventilation is the major goal and that during proximal high-frequency jet ventilation airway pressures should be monitored as far distally as possible.     

Pressure-controlled versus volume-controlled one-lung ventilation for MIDCAB

One-lung ventilation is limited by hypoventilation and hypoxemia because of increasing airway pressure and intrapulmonary shunt. Previous clinical studies compared pressure-controlled versus volume-controlled ventilation during one-lung ventilation in patients with pre-existing pulmonary disease. We studied 50 patients undergoing thoracotomy and one-lung ventilation because of cardiovascular disease. After two-lung ventilation with volume-controlled ventilation, patients were divided randomly into two groups. In one group, ventilation was switched to pressure-controlled ventilation after starting one-lung ventilation. In the other group, volume-controlled ventilation was continued. Parameters of ventilation, pulmonary function and systemic and pulmonary hemodynamics were recorded. We observed, that peak airway pressure, dead space ventilation and arterial carbon dioxide partial pressure were significantly higher during volume-controlled ventilation. After one-lung ventilation patients with pressure controlled ventilation had lower alveolar-arterial oxygen tension difference and a higher arterial oxygen partial pressure with significant differences for those patients in the intensive care unit. We conclude that pressure-controlled ventilation may be useful to improve gas exchange and alveolar recruitment during one lung ventilation.     

机械通气中人机对抗的防治对策

目的:探讨机械通气患者发生人机对抗的原因和防治对策。方法:对57例人机对抗患者进行回顾性分析。结果:104例机械通气患者中发生人机对抗57例(54.8%),其中死亡3例(5.3%)。其原因包括:气道阻塞30例,支气管痉挛6例,潮气量不足6例,持续高热5例,急性肺水肿4例,单肺通气3例,呼吸机漏气2例,气胸1例。结论:人机对抗的发生均有其诱发因素。气道阻塞、潮气量不足、急性肺水肿等是主要原因。加强气道管理、设置合适的通气量、解除气道痉挛、祛除诱因等综合有效防治措施,可避免和减少人机对抗的发生。     

Der Einflu\ biogener Amine auf die Atmung und den kleinen Kreislauf

The experiments were carried out on 30 dogs. Infusion of acetylcholine in the right atrium and in the truncus bicaroticus did not affect ventilation or pulmonary circulation as long as blood pressure in the systemic circulation remained stable. A short-term effect on ventilation was observed only at the beginning of the injection. In man, inhalation of acetylcholine leads to an irregular obstructive ventilation disturbance with severe impairment of the gas exchange, an increase of the pressure in the arteria pulmonalis and an increase of the ventilation frequency. In all this, pressure in the systemic circulation may be normal. The clinical picture in animals is similar to the one in patients with severe obstructive airway disease. The regulation of the ventilation frequency depends upon the localization of the airway obstruction. Airway obstruction more in the periphery of the airways causes an increase of frequency with increases in dead space ventilation. The increase of the pressure in pulmonary circulation followed the hypoxy and was found not to be directly influenced by acetylcholine. The airway obstruction following acetylcholine inhalation can be reversed in a relatively short period of time. Positive pressure inhalation eliminates such obstructions. The application of acetylcholine did not result in tachyphylaxis in experiments lasting longer than 5 hours. It seems that acetylcholine plays a decisive role in airway obstruction mechanisms in man.