Tip Of Endotracheal Tube Research Articles

Early radiographic signs of tracheal rupture.

Early diagnosis and repair of tracheal rupture are necessary to prevent acute tension pneumothorax, airway obstruction, and chronic tracheal stenosis. Few reliable radiographic signs of tracheal rupture have been proposed. We diagnosed seven cases of tracheal rupture, two related to blunt trauma and five resulting from tracheal intubation. Early radiographic signs included orientation of the distal portion of the endotracheal tube to the right relative to the lumen of the trachea with an overdistended endotracheal balloon cuff, migration of the balloon toward the endotracheal tube tip, and pneumomediastinum and subcutaneous emphysema. In four cases, the overdistended balloon with distal migration preceded the pneumomediastinum by several hours. An overdistended balloon in a patient after tracheal intubation or blunt chest trauma should suggest tracheal rupture.

High-Frequency Ventilation and Tracheal Injuries

Recent reports linking serious tracheal injuries to various forms of high-frequency ventilation prompted this study. We compared the tracheal histopathology seen following standard-frequency, conventional mechanical ventilation with that seen following high-frequency, conventional mechanical ventilation, and two different forms of high-frequency jet ventilation. Twenty-six adult cats were examined. Each was mechanically ventilated for 16 hours. Seven received standard-frequency, conventional mechanical ventilation at 20 breaths per minute. Seven received high-frequency, conventional mechanical ventilation at 150 breaths per minute. Six received high-frequency jet ventilation at 250 breaths per minute via the Instrument Development Corporation VS600 jet ventilator (IDC). Six received high-frequency jet ventilation at 400 breaths per minute via the Bunnell Life Pulse jet ventilator (BLP). A semiquantitative histopathologic scoring system graded tracheal tissue changes. All forms of high-frequency ventilation produced significant inflammation (erosion, necrosis, and polymorphonuclear leukocyte infiltration) in the trachea in the region of the endotracheal tube tip. Conventional mechanical ventilation produced less histopathology than any form of high-frequency ventilation. Of all of the ventilators examined, the BLP, the ventilator operating at the fastest rate, produced the greatest loss of surface cilia and depletion of intracellular mucus. IDC high-frequency jet ventilation and high-frequency, conventional mechanical ventilation produced nearly identical histologic injuries. In this study, significant tracheal damage occurred with all forms of high-frequency ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

1792 TRACHEAL INFLAMMATION AND HIGH-FREQUENCY VENTILATION

Tracheobronchial histopathology following conventional positive-pressure ventilation (CPPV) was compared to that following high-frequency positive-pressure ventilation (HFPPV) and two types of high-frequency jet ventilation. Twenty-six cats were each ventilated for 16 hours. Seven received CPPV via an infant ventilator (Bourns BP200) cycling at 30 bpm. Seven received HFPPV using the same ventilator cycling at 150 bpm. Six received HFJV via an IDC VS600 ventilator (HFJV1) cycling at 250 bpm. Six received HFJV using a Bunnell ventilator (HFJV2) cycling at 400 bpm. A 4-point, 9-variable histologic scoring system graded tissue changes at four levels of the tracheobronchial tree. High-frequency ventilation produced more inflammatory tracheal injury at the endotracheal tube tip when compared to CPPV (P <.05). CPPV produced more histopathology at the carina and brainstem bronchi (P <.05). There were no significant differences in injury patterns produced by HFJV1 or HFPPV; HFJV2 resulted in less lower airway damage than either HFJV1 or HFPPV (P <.05).In this study, high-frequency ventilation produced inflammatory injuries near the endotracheal tube tip. CPPV produced different and greater histopathology distally. These differences suggest that CPPV and high-frequency ventilation have different injury mechanisms. Tracheal inflammation seen with HFPPV suggests that frequency, not ventilator type, may be at least partially responsible for this lesion.

Neonatal High-Frequency Jet Ventilation: Four Years' Experience

During a 4-year period, 34 neonates were treated with high-frequency jet ventilation (HFJV) using two different HFJV systems. Twenty-three of the neonates had severe pulmonary air leaks, five had congenital left-sided diaphragmatic hernias, and six had end-stage respiratory failure without pulmonary air leaks. The two HFJV systems performed similarly in all pathologic conditions. Following HFJV, arterial blood gas values improved in 28 of the 34 patients (82%). Eleven patients (32%) ultimately survived. Of 23 patients with pulmonary air leaks, 17 (74%) improved, nine (39%) survived. One infant with diaphragmatic hernia and one with end-stage respiratory failure survived. Ten of 12 patients (85%) who died following eight or more hours of HFJV had significant tracheal histopathology in the region of the endotracheal tube tip. The lesions ranged from moderate erythema to severe necrotizing tracheobronchitis with total tracheal obstruction. HFJV can be useful in the treatment of severe pulmonary air leaks in neonates and may prove useful in the treatment of congenital diaphragmatic hernias. However, HFJV produces inflammatory injuries in the proximal trachea. More clinical and laboratory studies are needed to define the relative risks and benefits of this new therapy.

LUNG VOLUME, TIDAL VOLUME, AND ALVEOLAR PRESSURE DURING JET VENTILATION

We have measured lung volume (FRC), tidal volume delivered (VT), and alveolar pressures (PA) during jet ventilation of rabbits. The rabbits were ventilated with room air using the Healthdyne jet ventilator at a driving pressure of 4 psi and frequencies from 2 to 15 Hz. The 0.98 mm ID jet cannula was inserted 2 cm into a 3.5 mm endotracheal tube. Pressure was measured in the trachea (Ptr) just distal to the endotracheal tube tip, and in the alveoli. Alveolar pressure was measured by gluing an adapter to the pleural surface which had been exposed through a thoracotomy. After closing the thoracotomy, pleural punctures were made through the adapter and a pressure transducer was inserted. Volume was measured with a pressure plethysmograph. The animals were ventilated at 2, 5, 10 and 15 Hz, with inspiratory times (TI) of 10, 30 and 50%. There was a marked increase in FRC during jet ventilation, to 80% or more of total lung capacity at 50% TI. The increase in FRC was related to mean expiratory flow rate. Mean PA and Ptr were equal and exceeded mean pressure at the airway opening. Tidal volume diminished with increasing frequency, and was greatest at 30% TI at any frequency. VT exceeded estimated dead space below 10 Hz. PA swings were equal to Ptr swings, fell with increasing frequency and were least at 10% TI. We conclude that dangerously large increases in FRC may occur during jet ventilation, and that measurement of pressure at the airway opening is an inadequate means of monitoring airway pressures during jet ventilation. (Supported in part by HL 27372.)

Radiological Evaluation of Patients Receiving Assisted Ventilation

WITH the increasing use of tracheal intubation and mechanical ventilators for respiratory support, both clinician and radiologist are seeing an increased number of portable roentgenograms of patients receiving assisted ventilation. An understanding of the expected radiological appearance and potential complications should help decrease the frequency of iatrogenic problems in these critically ill patients.¹ <h3>Endotracheal Tube</h3> The ideal location for the tip of the endotracheal tube is 5 to 7 cm from the carina. This places the tip midway between the carina and the vocal cords. When the carina is not visible, its position may be approximated from prior portable films or by using the vertebral bodies as reference markers. On 95% of portable roentgenograms, the carina projects over the fifth, sixth, or seventh thoracic vertebral body.¹ Proper positioning of the tube is important because flexion or extension of the neck moves the endotracheal tube tip relative to the

Alteration of endotracheal tube position. Flexion and extension of the neck.

Malposition of the endotracheal tube is a frequent complication in patients being treated for ventilatory failure. It was suspected that motion of the head might alter the position of the tube and result in malposition. Twenty adult patients with ventilatory failure, in tubated with an 8.0-mm endotracheal tube (5 oral and 15 nasal) were studied. The cuff was deflated in 10 of the 20 patients. With the patient in a semierect sitting position, standardized portable anterior-posterior chest roentgenograms were obtained with the neck in flexion, neutral, and hypertension and in 5 of the patients after right lateral head rotation. Movement of the endotracheal tube tip relative to the carina was measured from each roentgenogram. The endotracheal tube moved a similar distance regardless of the route of intubation or the inflation status of the cuff. Therefore, all groups were combined for analysis. The tube moved an average of 1.9 cm toward the carina with flexion from a neutral position, 1.9 cm away from the carina with extension, and 0.7 cm away with lateral head rotation. Malposition of the endotracheal tube may result from changes in head position. To minimize the possible injurious effects of that malposition, we recommend that the tip of the endotracheal tube be placed in the middle third of the trachea with the neck in a neutral position. Finally, knowledge of the head position is crucial to the proper radiographic interpretation of endotracheal tube position.

Proper position of the endotracheal tube tip on chest radiographs

Proper position of the endotracheal tube tip on chest radiographs