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Comparison of the LoTrach and the Portex Soft Seal cuff: tracheal wall pressure and fluid leakage in a benchtop study and a clinical study

Introduction

The objective of the study is to demonstrate two methods of measuring tracheal wall pressure (in vitro and in patients), with the LoTrach (LVLP) cuff and with conventional high-volume low-pressure (HVLP) cuffs. The LoTrach (VTSL, Singapore) is a new tracheal tube designed for use for mechanical ventilation in the critically ill. The LoTrach has been shown to prevent the ubiquitous problem of micro-aspiration of secretions associated with conventional HVLP cuffs [1]. Aspiration prevention is achieved by the properties of the LoTrach's low-volume low-pressure (LVLP) cuff, and these have been previously described [1, 2]. It is important that, alongside achieving aspiration prevention, there is also tracheal wall pressure control. The LoTrach LVLP cuff is calibrated such that the sum of the elastic forces within the cuff remain constant throughout the inflation profile. Thus, at the working intra-cuff pressure of 80 cmH2O, only a consistent and acceptable 30 cmH2O is transmitted to the tracheal wall [2].

Methods

Benchtop model

Four tracheal tubes (8 mm internal diameter) were studied; the LoTrach, Portex SoftSeal, Microcuff and Mallincrokdt HiLo Evac. The model trachea had an internal diameter of 2.4 cm and the cuff was inflated with a Tracoe constant pressure device. The cuff was overpressured while fluid was instilled above the cuff to a height of 50 cm. The stopwatch was started as the pressure was reduced to the test pressure of 30 cmH2O. The rate of fall of the resulting column of fluid was then measured.

Clinical study

Intubated patients underwent a staged recruitment manoeuvre while the intracuff pressure was maintained with a Tracoe cuff inflator. The PEEP was set to 15 cmH2O and then increased in 5 cmH2O increments every 5 seconds until 40 cmH2O was achieved. A second observer auscultated the anterior neck and the pressure at which air leak was heard was recorded. Two tubes were studied; LoTrach (at 80 cmH2O intracuff pressure = 30 cmH2O calculated wall pressure) and Portex Soft Seal (30 cmH2O).

Results

Conventional HVLP cuffs do not prevent leakage of fluid past the cuff, hence the negative slope on the graphs. The LoTrach cuff does not leak and therefore the line is horizontal (see Figure 1). The clinical study shows that both the LoTrach and Portex cuffs demonstrate a gross air leak at equal and acceptable tracheal wall pressures at 33.4 and 29.7 cmH2O, respectively (see Table 1).

Figure 1
figure1

abstract

Table 1 abstract

Conclusion

In the benchtop model, the LoTrach LVLP cuff demonstrates an acceptable wall pressure of 30 cmH2O (at an intracuff pressure of 80 cmH2O), while achieving the prevention of leakage of fluid past the cuff. The clinical study demonstrates that the tracheal wall pressure was both acceptable and equal for both the Portex HVLP and the LoTrach LVLP cuffs. The LoTrach prevents micro-aspiration in the benchtop model with acceptable tracheal wall pressures in both the benchtop and clinical studies.

References

  1. 1.

    Young PJ, Pakeerathan S, Blunt MC, Subramanya S: A low-volume, low-pressure tracheal tube cuff reduces pulmonary aspiration. Crit Care Med 2006, 34: 632-639. 10.1097/01.CCM.0000201406.57821.5B

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  2. 2.

    Young PJ, Young WH: Inflation of a pressure-limited cuff inside a model trachea. Med Eng Phys 2003, 25: 465-473. 10.1016/S1350-4533(02)00252-7

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Evans, L., Blunt, M., Arunachalam, C. et al. Comparison of the LoTrach and the Portex Soft Seal cuff: tracheal wall pressure and fluid leakage in a benchtop study and a clinical study. Crit Care 11, P215 (2007). https://doi.org/10.1186/cc5375

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Keywords

  • Tracheal Tube
  • Wall Pressure
  • Recruitment Manoeuvre
  • Tracheal Wall
  • Anterior Neck