Tracheal tube cuffs and tracheal dilatation

Comparison of the cuff pressures of a TaperGuard endotracheal tube during ipsilateral and contralateral rotation of the head: A randomized prospective study

BACKGROUND

Maintaining optimal intracuff pressure of the endotracheal tube is important during airway management. Rotation of the head can affect the cuff pressure of the endotracheal tube. We investigated the change in cuff pressure and the degree of tube displacement according to the direction of head rotation (toward the same side vs opposite side of tube fixation) using a TaperGuard endotracheal tube.

METHODS

We conducted a prospective study in 58 patients, aged 18 to 70 years, who underwent tympanomastoidectomy under general anesthesia. TaperGuard endotracheal tube was secured at the corner of the mouth, either on the same side as that of the head rotation (Group S, n = 29) or on the opposite side (Group O, n = 29). After endotracheal intubation, the endotracheal tube cuff pressure was set at 22 cmH2O in the neutral position of the head. The cuff pressure was measured again after lateral rotation of the head and readjusted to 22 cmH2O. In addition, the change in distance from the carina to the tip of the endotracheal tube was measured before and after the change in position. The incidences of cough, sore throat, and hoarseness were assessed at 30 minutes, 6 hours, and 24 hours after surgery.

RESULTS

There were no differences between groups in terms of patient characteristics and duration of anesthesia. The change in cuff pressure after head rotation in Group S (8.07 ± 1.07 cmH2O) was greater than that in Group O (2.24 ± 0.95 cmH2O) (P < .001). In addition, 21 (72.4%) patients in Group S and no patient in Group O had pressures above 30 cmH2O (P < .001). Furthermore, the tube tip moved away from the carina by 8.55 ± 7.01 mm in Group S and by 2.83 ± 4.72 mm in Group O (P < .001).

CONCLUSION

Fixation of the TaperGuard endotracheal tube on the side contralateral to head rotation was associated with a smaller intracuff pressure increase and lesser tube displacement compared to fixation of the tube on the ipsilateral side.

Effect of Lanz Pressure Regulating Valve on Self-sealing Mechanism and Air Leakage Across the Tracheal Tube Cuffs in a Benchtop Model

Background:

The aim of the present study was to investigate the effect of the Lanz system on air sealing by self-inflation in high volume–low pressure (HVLP) tube cuffs.

Methods:

In vitro tracheal air sealing was studied in HVLP tracheal tube cuffs (internal diameter [ID] 8.0 mm) made from polyurethane ([PU] Seal Guard tracheal tube, Covidien, Athlone, Ireland) and from polyvinylchloride ([PVC] HiLo tracheal tube, Covidien) with and without Lanz pressure regulating valve. Tube cuffs were placed in a vertical 22 mm ID artificial trachea and inflated to 5, 10, 15, 20, 25, or 30 cm H2O cuff pressures. Pressure control ventilation with peak inspiratory pressures (PIPs) of 20 or 25 cm H2O was applied and air leakage was assessed spirometrically as the ratio of expiratory to inspiratory tidal volumes. Nonparametric Mann-Whitney test was applied to compare the air leakage with and without Lanz system for both cuff types at each cuff pressure and PIP ( P < .05).

Results:

The PVC tube cuffs with Lanz system resulted in significant air leakage at both 20 and 25 cm H2O PIP as compared to those without the Lanz system, especially at cuff pressures lower than the preset PIP ( P < .05). Although PU tube cuffs with Lanz system showed reduced air sealing when compared with cuffs without Lanz, the difference was not statistically significant.

Conclusion:

Cuff pressure compensation with the Lanz system during cyclic respiratory pressure changes interferes with the self-sealing mechanism in HVLP tube cuffs at cuff pressures lower than PIP level. This results in larger air leak across tube cuffs particularly in tube cuffs made from PVC.

Comparison of air-sealing characteristics of tapered- vs. cylindrical-shaped high-volume, low-pressure tube cuffs

BACKGROUND

This study aimed at comparing air-sealing characteristics of the new tapered-shaped tracheal tube cuffs with cylindrical tube cuffs.

METHODS

Tracheal tubes with tapered-shaped polyurethane (PU) and polyvinyl chloride (PVC) cuffs as well as standard cylindrical-shaped cuffs made of PU and PVC (Covidien, Athlone, Ireland) were investigated. A tracheal model attached to a test lung was intubated, and cuffs were inflated to 10, 15, 20, 25 and 30 cm H(2)O. The test lung was ventilated with intermittent positive pressure ventilation at peak inspiratory pressures (PIPs) of 20 and 25 cm H(2)O. Air leakage was assessed by spirometry and measurement of sevoflurane concentration passing the cuff at the upper cuff border using an anaesthetic gas analyser. Experiments were repeated four times with new tracheal tubes for each run. Statistical comparisons were done using Mann-Whitney U-test with level of significance at P < 0.05.

RESULTS

The tapered-shaped PVC tube cuff demonstrated a significantly lower air leakage determined by spirometry than the cylindrical-shaped cuff at both PIPs (20 and 25 cm H(2)O). Similarly, sevoflurane leakage was less with the tapered PVC cuff particularly at higher cuff pressures. With the PU cuff, reduction in air leakage by a tapered-shaped compared with a cylindrical-shaped tube cuff was not significant.

CONCLUSIONS

A tapered-shaped tube cuff considerably improves air-sealing characteristics of PVC tube cuffs and allows thereby reducing cuff pressure required for sufficient ventilation. In tube cuffs made of PU that exhibits superior sealing characteristics compared with PVC, a tapered shape failed to result in a further reduction of air leakage.

Survey of Cuff Management Practices in Intensive Care Units in Australia and New Zealand

Background Cuff management varies widely in Europe and North America. Little is known about current practice in Australia and New Zealand.

Objective To characterize important aspects of cuff management in intensive care units in Australia and New Zealand to compare with international reports.

Methods A questionnaire was sent to all nurse managers of adult intensive care units in Australia and New Zealand.

Results Survey response was 53% (92/175). After intubation, most units (50/92, 54%) used both minimal occlusive volume technique and cuff pressure measurement; 5 (5.5%) used these methods along with pilot balloon palpation. Twenty units (22%) used cuff pressure measurement exclusively and 16 units (17.5%) used the minimal occlusive volume technique exclusively. Only 1 unit (1%) used the minimal leak technique after intubation. For ongoing management, cuff pressure measurement was the preferred method, used exclusively in 42 units (46%), with the minimal occlusive volume technique used in 40 units (43%; sole method in 6 units [7%]) and palpation in 4 units (4%). In most units (65/92, 71%), cuffs were monitored once per nursing shift. In units using the minimal occlusive volume technique, oropharyngeal suctioning (74%) and semirecumbent positioning (58%) were routinely incorporated; sigh breaths (6%), discontinuation of enteral feeding (10%), and nasogastric tube aspiration (26%) were uncommon. Cuff management protocols (37%) and subglottic suctioning (12%) were used infrequently.

Conclusions Cuff pressure measurement was the preferred method, used exclusively or in combination with other methods. The minimal occlusive volume technique was used more often after intubation than for ongoing management.

Tracheal sealing by auto-inflation in tracheal tube cuffs

BACKGROUND

The purpose of this study was to determine if inspiratory pressure from intermittent positive pressure ventilation may be sufficient to inflate the cuff (thus 'auto-inflation') and thereby seal the trachea.

METHODS

In a laboratory model we investigated the ability of cuffs of seven 5.0 mm internal diameter (ID) tracheal tubes (Sheridan CF, Mallinckrodt Hi-Contour, Mallinckrodt Sealguard, Mallinckrodt Safety-Flex, Portex Soft Seal, Rueschelit Super-Safety Clear and Microcuff PET) to seal the trachea by auto-inflation, i.e. by using the inspiratory pressure to expand and keep open the cuff within the trachea. A mechanical lung connected to a model trachea made from clear, rigid polyvinylchloride (PVC) (12 mm ID) was used to simulate changes in inspiratory pressures. Respirator settings were: fresh gas flow (air) 6 lxmin(-1); positive end-expiratory pressure 5 cmH(2)O; respiratory rate 20 brxmin(-1); I : E ratio = 1 : 2; inspiratory pressure 5, 10, 15, 20, and 25 cmH(2)O. Percentage of expiratory to inspiratory tidal volume (E : I V(t) volume ratio) was calculated.

RESULTS

Using lubricated Mallinckrodt Seal Guard tube cuffs E : I V(t) volume ratio was almost 100% at a peak inspiratory pressure of 10 cmH(2)o whereas in tube cuffs particularly made of PVC an E : I ratio was achieved only at higher inspiratory pressures, if at all.

CONCLUSIONS

Auto-inflation in the Mallinckrodt Seal Guard with high volume-low pressure polyurethane cuff can produce adequate tracheal sealing in the model trachea used. The implication is that such auto-inflation should decrease the risk of tracheal injury from acute or persistent cuff hyperinflation.

Acute tracheal rupture related to endotracheal intubation: case report

Tracheal laceration is a rare complication of endotracheal intubation. We present a case of tracheal laceration after a simple prehospital tracheal intubation in a patient with severe tracheomalacia. The most likely cause of the tracheal injury was massive overinflation of the endotracheal tube cuff and the preexisting tracheal wall weakness. The case illustrates the classic radiologic signs of tracheal laceration, and we review the relevant literature.

Utility of portable chest radiographs as a predictor of endotracheal tube cuff pressure

Increased endotracheal tube cuff pressure causes mucosal ischemia that can lead to necrosis, infection, and, eventually, tracheomalacia or tracheal stenosis. Endotracheally intubated patients frequently undergo portable chest radiography. In this study we explored the relationship of endotracheal tube cuff pressure and the appearance on the tracheal air columns on the portable chest radiograph. We measured the endotracheal tube cuff pressure of intensive care unit patients 124 times immediately before portable chest radiography. On 64 of these radiographs we measured the width of the tracheal air column below the tip of the endotracheal tube and at the maximal diameter of the endotracheal tube balloon. We then analyzed the relationship of cuff pressure to tracheal dilation. The results of ANOVA of tracheal dilation for three groups (safe, borderline, and unsafe cuff pressures) were significant. Large overlapping ranges existed in each group. Regression analysis confirmed a linear relationship between cuff pressure and tracheal dilation (r = 0.435, p < 0.001). Predicted tracheal expansion at 20 mm Hg was a poor screen for endotracheal tube cuff inflation safety; the sensitivity was only 56% and specificity only 71%. The differences in the capacity for tracheal distension between patients make these findings not unexpected. The portable chest radiograph is a poor screening tool for unsafe endotracheal tube cuff pressure.

Effect of tracheal dilatation and rupture on mechanical ventilation using a low-pressure cuff tube

We report the case of a 36-year-old woman who suffered tracheal dilatation and rupture despite careful monitoring of intracuff pressure. Surgical manipulation, postoperative mediastinitis, and bacterial staphylococcal tracheitis may be involved in the development of this complication.

Mechanical ventilation of a patient with decreased lung compliance and tracheal dilatation

Tracheal injury resulting from tracheal intubation is common. Injuries vary in type and severity, from mucosal sloughing to tracheal stenosis and fistula formation. We report a patient with poor lung compliance and massive tracheal dilatation as a result of prolonged mechanical ventilation with high inflation pressure despite the use of a high-volume, low-pressure cuff. To reduce the tracheal dilatation but maintain adequate ventilation and continuous positive airway pressure, we substituted a longer double-cuff tracheotomy appliance and used an automatic intermittent cuff inflator. The problems related to the design of modern tracheal tube cuffs are discussed.

Complications of acute respiratory failure

Acute respiratory failure is frequently fatal. Attempts to decrease mortality must include attention to pulmonary and extrapulmonary complications. Pulmonary complications include pulmonary emboli, barotrauma, fibrosis, and pneumonia. Swan-Ganz catheters, tracheal intubation, and mechanical ventilation can also result in pulmonary complications. Extra-pulmonary complications such as gastrointestinal hemorrhage, renal failure, infection, and thrombocytopenia may increase mortality. Early diagnosis, aggressive treatment, and prophylaxis of complications should increase survival.

Pressures on endotracheal tube cuffs

The general relationships between the pressure inside an endotracheal tube cuff, the pressure exerted by that cuff on the tracheal wall and the airway pressure have been re-examined in a model system. In relatively recent literature, the tracheal wall pressure at a given cuff volume has been calculated as the difference between intracuff pressures at that volume when the cuff is inflated inside the trachea and when it is inflated whilst suspended freely in air. This has been used as a general relationship, as an alternative to direct measurement in real and model tracheas. In this study, the directly measured pressure was not generally equal to the pressure as calculated above.

Tracheo-graft fistulae following pharyngo-laryngo-oesophagectomy. A cause and its prevention

Tracheo-graft fistulae developed in two patients who required intermittent positive pressure ventilation and intubation with conventional cuffed tracheostomy tubes following resection of post-cricoid carcinomata by pharyngolaryngo-oesophagectomy. Pressure necrosis of the posterior tracheal muscle and the anterior wall of the graft occurred as a direct result of compression of these structures between the tracheostomy cannula and air cuff, and the vertebral bodies at the thoracic inlet. This post-operative complication has not been encountered in subsequent resections since the introduction and routine use of a modified cuffed tracheostomy tube. The adjustable neck plate guards against trauma to the tracheostome, inadvertent intubation of one of the major bronchi in each individual patient and the siting of the cuff beyond the thoracic inlet. Unintentional over-inflation of air cuffs remains a hazard whereas only ambient air re-expands the foam cuff. This property of the cuff also ensures against surgical injury to the posterior tracheal wall during the operation. Pressure necrosis of the posterior tracheal wall by the main tracheostomy cannula is minimised by suitably modifying the curvature and length of the cannula for use in patients with end-tracheostomies.