Critical Care Medicine. Fluid leakage around tracheal tubes with different cuffs in ICU patients. Original Articles - Clinical Investigations

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1 Fluid leakage around tracheal tubes with different cuffs in ICU patients Journal: Manuscript ID: Manuscript Type: Date Submitted by the Author: draft Original Articles - Clinical Investigations n/a Complete List of Authors: Lucangelo, Umberto; Cattinara Hospital, Periopertive Medicine. Intensive Care and Emergency Zin, Walter; Federal University of Rio de Janeiro, Carlos Chagas Filho Institute of Biophysics Antonaglia, Vittorio; Cattinara Hospital, Periopertive Medicine. Intensive Care and Emergency Petrucci, Lara; Cattinara Hospital, Periopertive Medicine. Intensive Care and Emergency Viviani, Marino; Cattinara Hospital, Periopertive Medicine. Intensive Care and Emergency Giovanni, Buscema; Cattinara Hospital, Periopertive Medicine. Intensive Care and Emergency Borelli, Massimo; University of Trieste, Department of Mathematics and Computer Science Berlot, Giorgio; Cattinara Hospital, Periopertive Medicine. Intensive Care and Emergency Key Words: tracheal tube, microinhalation, ventilator-associated pneumonia, positive end-expiratory pressure, ; volume-controlled mechanical ventilation, bronchoscopy, Evans blue

2 Page of 0 Fluid leakage around tracheal tubes with different cuffs in ICU patients Umberto Lucangelo, MD; Walter A. Zin*, MD, DSc; Vittorio Antonaglia, MD; Lara Petrucci, MD; Marino Viviani, MD; Giovanni Buschema, MD; Massimo Borelli #, Giorgio Berlot, MD Department of Perioperative Medicine, Intensive Care and Emergency, Cattinara Hospital, Trieste University School of Medicine, Strada di Fiume, I- Trieste, # Department of Mathematics and Computer Science, University of Trieste, Italy and *Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Ilha do Fundao, -00 Corresponding author: Rio de Janeiro RJ, Brazil Umberto Lucangelo Dipartimento di Medicina Perioperatoria, Terapia Intensiva ed Emergenza Ospedale di Cattinara, Strada di Fiume I- Trieste Italy Phone: FAX: u.lucangelo@fmc.units.it Reprints will not be ordered Financial Support. Department of Perioperative Medicine, Intensive Care and Emergency, Cattinara Hospital, Trieste University School of Medicine, Trieste, Italy Key words: tracheal tube; microinhalation; ventilator-associated pneumonia; positive endexpiratory pressure; volume-controlled mechanical ventilation; bronchoscopy; Evans blue

3 Page of 0 Abstract Objective: To test the leakage of fluid around cuffs of different tracheal tubes in mechanically ventilated patients and in a benchtop model. Design: Randomized clinical trial and experimental in vitro study. Setting: General Intensive Care Unit, University Hospital. Patients: Forty patients recovering in the ICU were ventilated in volume-controlled mode. Twenty patients were randomly intubated with Hi-Lo tubes (HL group) whereas the remaining subjects were intubated with SealGuard tubes (SG group). Interventions: Immediately after intubation and cuff inflation with cm H O Evans blue was applied onto the cephalad surface of the tracheal tube cuff. A -cm H O PEEP was used during the first hours of stay and thereafter it was removed. Bronchoscopy verified whether the dye leaked around the cuff. The experiment lasted hours. Leakage was also tested in vitro with the same tracheal tubes. Measurements and Main Results: At,, and thereafter on an hourly basis until hrs bronchoscopy tested the presence of dye on the trachea caudad to the cuff. On the th hour patients of HL group failed the test. One hr after PEEP removal all subjects in group HL exhibited a dyed lower trachea. On the other hand, one patient in group SG presented a leak at the th hr and at the th hr of them were still sealed. In vitro the same level of PEEP delayed the passage of dye around the cuff; after min PEEP was removed and in 0 min all dye leaked. Longitudinal and oblique folds could clearly be seen on the Hi-Lo tube. Conclusions: Five cm H O PEEP was effective in delaying the passage of fluid around the cuffs of tracheal tubes both in vivo and in vitro. SealGuard tube proved to be more resistant to leakage than Hi-Lo.

4 Page of 0 It has been demonstrated that high-volume low-pressure tracheal tubes (HVLP) do not avoid the contamination of the lower airway by secretions leaking from the subglottis and above (, ). This finding owes to the longitudinal folds within the cuff wall that occur on its inflation within the trachea even if adequate pressure (- cm H O) is used (, ). Contamination of the lower airways may ensue and promote ventilator associated pneumonia (VAP) (-). VAP is a very important cause of prolongation of stay and death in the ICU. Silent aspiration of upper airway secretions has been reported in patients undergoing general anesthesia (, ) and in the intensive care unit (-). In addition, interesting in vitro models have been employed to demonstrate that even under favorable conditions leakage can still be detected (-). However, it was minimized with HVLP tubes, thus implying that the material used in the cuffs and their shape may be of paramount importance in determining whether microinhalation will take place. The use of positive end-expiratory pressure (PEEP) may also contribute to seal the leakage (). Thus, the aims of this study were: a) to evaluate for hrs the possible occurrence of leakage around cuffs made of PVC or polyurethane inflated with cm H O in ICU patients, and b) use in vitro measurements to identify the possible causes for the leakage. MATERIALS AND METHODS Patients and design of the study. Forty consecutive adult patients admitted to the ICU of Cattinara Hospital from January to October 0 that required immediate orotracheal intubation and mechanical ventilation because of deterioration of consciousness state (Glasgow Coma Scale ) were studied in the semirecumbent position (- o ). The exclusion criteria were COPD, active pneumonia, previous surgery of the upper airway or

5 Page of 0 larynx, obesity, or other causes that increased abdominal pressure or jeopardized normal chest wall function. The patients were randomly divided into two groups of patients each at admission by a physician unaware of the study: those intubated with Hi-Lo tracheal tubes (Mallinckrodt Medical, Cornamady, Athione County, Ireland) and those receiving SealGuard tubes (Mallinckrodt Medical, Cornamady, Athione County, Ireland), groups HL and SG respectively. Before intubation propofol ( mg/kg BW) and succinylcholine chloride ( mg/kg BW) were injected intravenously if required. All patients were mechanically ventilated in volume-control mode with a 0 Puritan- Bennett ventilator (Puritan-Bennett Corporation, Carlsbad, CA, USA) with tidal volume of - ml/kg and respiratory rate (- bpm) to maintain normocapnia, and cm H O of positive end-expiratory pressure (PEEP) were immediately applied. Tracheal tube size was chosen following the Higenbottam-Payene equation () and the cuff was inflated with air to a pressure of cm H O, as checked out with an aneroid manometer (Mallinckrodt Medical, Cornamady, Athione County, Ireland). A careful aspiration of upper and lower airways secretions ensued. One ml of Evans blue diluted in ml of saline solution (NaCl.%) were then carefully placed on the top of the cuff. One and hrs after intubation fiber optic bronchoscopy was performed to detect the possible presence of blue dye in the trachea, according to the modified Evans blue dye test (MEBDT), as recently reevaluated (). Thereafter PEEP was removed and bronchoscopy performed on an hourly basis until hrs after intubation. If at any occasion a blue spot was seen on the trachea caudad to the tube s tip, the leakage was confirmed and the experiment finished. In all instances the bronchoscope tip was never introduced below the tube s distal end. Mouth and tracheal secretions were not aspirated during the whole experiment.

6 Page of 0 The investigation was approved by the local Ethics Committee, and informed consent was obtained from each patient s next of kin. Statistical analysis. Statistical analysis was performed by the open source statistical package R (). Likelihood ratio test was used to assess significance in Cox regression model analysis (, ) and logrank test was used to assess difference in survival analysis between the two groups of tracheal tubes (). In vitro study. Two 00-ml pyrex measuring cylinders (internal diameter =. cm) served as a vertical trachea model. One was intubated with a size. (i.d.) Hi-Lo tracheal tube (Mallinckrodt Medical, Cornamady, Athione County, Ireland) and the other with a size. (i.d.) SafeGuard tube (Mallinckrodt Medical, Cornamady, Athione County, Ireland). The same pressure ( cm H O) was simultaneously applied to both cuffs via a Y tube connected to an aneroid manometer (Mallinckrodt Medical, Cornamady, Athione County, Ireland). Through the tubes a cm H O CPAP/PEEP was concomitantly applied to both measuring cylinders by means of a -L syringe. One ml of Evans blue diluted in ml of saline solution (NaCl.%) was added to the top of each cuff. After min CPAP/PEEP was removed. Fluid leakage past tube cuffs was looked for. The study lasted min. The experiment was repeated twice with new tubes of each kind. RESULTS Table shows the anthropometric and functional characteristics of our patients at admission to the ICU. The two groups presented similar average values of height, weight and age. In the HL group patients received size. tubes and were intubated with size tubes, whereas in the SG the respective data were 0 and 0.

7 Page of 0 Figure shows that at the th hour after intubation dye was detected for the first time in the lower trachea of patients of the HL group (figure ). At this time PEEP was removed. One hour afterwards all the patients of the HL group presented fluid leakage around the tracheal tube cuff. At the th hr the first patient of the SG group showed dye in the lower trachea. At the end of the experiment ( hrs) patients of this group still depicted sealed tracheal cuffs (figure ). Evidence about the statistically significant difference in global behavior between the two groups of patients was assessed by the logrank test ( z = -., P < 0 - ). Figure depicts the two tubes [Hi-Lo (on the left) and SealGaurd (on the right)] with inflated cuffs ( cm H O) inside measuring cylinders (CPAP/PEEP below the cuffs = cm H O) right after the application of Evans blue on the top of the cuffs. While the SealGaurd tube presented a clear cuff sealed against the tube wall, the other one showed longitudinal and oblique folds within the cuff wall clearly dyed in blue. At 0 min after the removal of CPAP/PEEP ( min after the application of Evans blue on the top of the cuffs) all liquid had passed around the cuff of the Hi-Lo tube and the folds are very well defined, whereas no fluid leaked around the SealGuard cuff (figure ). The same results were found in the second identical experiment. DISCUSSION The leakage of fluid past tracheal tube cuffs still represents a potential hazard for intubated patients. Different cuff shapes and materials have been continuously developed, together with other measures such as recumbent position of the thorax and continuous subglottic aspiration (, ). However, the solution still remains to be provided.

8 Page of 0 In benchtop models the use of positive pressure simulating the use of PEEP or CPAP has been proved to minimize the microinhalation of liquid around the tube cuff (, ). Different cuff inflation pressures have also been tested and low pressures, such as 0 cm H O, resulted in a significant leakage (). Thus, we aimed to test in intubated and mechanically ventilated patients using high-volume low-pressure tracheal tubes the possible contribution of PEEP to minimize the passage of fluid into the trachea. The same tubes were also tested in vitro to provide experimental support to the in vivo results. Two tubes were randomly tested in two similar groups of patients each. Those belonging to the HL group were intubated with a Hi-Lo tracheal tube (Mallinckrodt Medical, Cornamady, Athione County, Ireland), whose cuff is made of PVC, whereas those in SG group received a SafeGuard tube (Mallinckrodt Medical, Cornamady, Athione County, Ireland) with a polyurethane cuff. The tube size for each patient was adequately calculated according to their individual anthropometric data (). To our knowledge no long-duration study has been recently done in patients to address the occurrence of leakage of fluid past the tracheal tube with either PVC or polyurethane cuffs. During the first hours of the study our patients were ventilated with a PEEP of cm H O and two patients of the HL group failed (figure ). PEEP was then removed and the remaining patients of this group presented a blue spot on the trachea one hour later. In the SG group, however, the first patient failed on the th hr after intubation and on the th hr three cases were still sealed. Lower tracheal aspiration did not collect blue secretions in these patients. The two groups were significantly different in global behavior (logrank test, P < 0 - ). We stress that although PEEP was removed during the experiment, this factor can be considered as a time-dependent covariate in a Cox regression analysis framework. Studying the maximal model (i.e., time dependency and PEEP included as a covariate) and simplifying from not significant interactions, a minimal adequate model can be fitted to the data and a hypothesis

9 Page of 0 test confirming the former significant difference between groups can be checked (Likelihood ratio test statistics. on degree of freedom, Weibull distributed, P = 0). There is only one study in the literature () comparing the sealing properties of cuffs made out of polyurethane and PVC. The latter, in fact, was the Hi-Lo one also used in the present investigation. The authors applied methylene blue on top of the cuffs one hour prior to extubation and immediately after removal of the tube they performed a bronchoscopy to investigate the presence of blue dye on the lower trachea. They also found that the polyurethane cuff provided a better sealing than the PVC one (0% vs..% seepage, respectively). This result is in line with ours: at hrs under PEEP 0% of the patients in HL group resulted positive to the MEBDT against 0% in the other group. It should be stressed that Petring et al () did not use PEEP in their study. Another work demonstrated in humans that high-volume low-pressure cuffs tended to be superior regarding cuff seal in comparison with other designs () although controversial results can also be found in the literature (). Finally, it must be pointed out that theoretically spontaneous breathing and tracheal aspiration may lower the pressure in the cuff, thus increasing leakage around it. Many studies addressed the sealing properties of the tracheal tube cuff. Some authors, using pig or model tracheas, compared Hi-Lo tubes with other tubes and concluded that the former avoided seepage around the cuffs to a larger extent than the others (,, ). These studies, however, did not take into consideration the pressure beyond the cuffs, although they verified the effects of different pressures inside the cuffs and the time required for the leakage to occur. No polyurethane cuff has been tested in vitro so far. Considering the data gathered from our patients we decided to analyze a benchtop model in which a cm H O PEEP and PVC and polyurethane cuffs could be tested under a cuff inflation pressure equal to cm H O. The same types of tubes used in our clinical study were used, but only tube size. was employed. The geometric characteristics of the Hi-Lo

10 Page of 0 cuffs (inflation pressure of cm H O) resting on the bench were: length =. cm, circumference = 0 cm, volume = ml, diameter =. cm, spindle-like shape; SealGuard cuffs: length =. cm, circumference =. cm, volume = ml,, diameter =. cm, cylindrical. In fact the shape of the tubes has been reported as playing a role in the tube sealing properties (). In the present case, SealGuard cuffs were longer and narrower than the Hi-Lo cuff; both were wider than the trachea. Additionally, the former is made of polyurethane while the latter uses PVC. The former is more pliable and more rubberlike than the latter, which may improve its ability to better avoid seepage. In humans (without PEEP) the polyurethane tube proved to better seal the trachea in a time span of hrs (). To our knowledge ours is the first in vitro study comparing the sealing properties of these two tubes. Taking into consideration the use of CPAP/PEEP, it has been reported that cm H O CPAP/PEEP delays the leakage in model trachea () and silicone tube () preparations. We used measuring cylinders (i.d. =. cm) to simulate the trachea and only a small ( mm H O) head of pressure above the cuff (fig. ) to minimize gravitational forces, as reported by Young et al (). Qualitatively our results resemble those of Janson and Poulton (): they reported a smaller leakage and a longer time to seepage when CPAP/PEEP was applied to their model (size. HVLP Mallickrodt tube). In our case, with PEEP no leakage was detected in both tubes until min had elapsed, although the longitudinal and oblique folds found in the Hi-Lo tube displayed colored liquid (fig. ). Additionally we noted tiny bubbles moving proximally through the folds in the Hi-Lo tubes, which possibly reflects the pneumatic effect generated by the higher pressure distal to the cuff. When CPAP/PEEP was nil they () found a shorter average time ( min) before leakage than in the presence of PEEP ( min). We found that 0 min after PEEP removal all liquid ( ml) had passed around the cuff of the Hi-Lo tube, whereas the SealGard retained the dye above the cuff (fig. ).

11 Page 0 of 0 Thus the present in vitro observations support our clinical findings. In conclusion, the use of cm H O PEEP improved the sealing around high-volume low-pressure cuffs, specially in the polyurethane one.

12 Page of 0 Acknowledgements Dr. W.A. Zin is a researcher of the Brazilian National Council for Scientific and Technological Deveolpment (CNPq/MCT), Brazil, and a Visiting Professor at the School of Critical Care, Facoltà di Medicina, Università degli Studi di Trieste, Italy.

13 Page of 0 REFERENCES. Pavlin EG, Van Nimwegard D, Horbein TF: Failure of a high-compliance low-pressure cuff to prevent aspiration. Anestehsiology ; :-. MacRae W, Wallace P: Aspiration around high-volume low-pressure endotracheal cuff. Br Med J ; :. Seegobin RD, Van Hasselt GL: Endotracheal cuff pressure and tracheal mucosal blood flow: endoscopic study of effects of four large volume cuffs. Br Med J ; :-. Cook D, De Jonghe B, Brochard L et al: Influence of airway management of ventilatorassociated pneumonia. JAMA ; :-. Cook D, Walter SD, Cook RJ et al: Incidence of and risk factors for ventilator-associated pneumonia in critically ill patients. Ann Intern Med ; :-. Heyland DK, Cook DJ, Griffith L et al: The attributable morbidity and mortality of ventilator-associated pneumonia in the critically ill patient. Am J Respir Crit Care Med ; :-. Bernard WN, Cottrell JE, Sivakumaran C et al: Adjustment of intracuff pressure to prevent aspiration. Anesthesiology ; :-. Petring OU, Adelhøj B, Jensen BN; Prevention of silent aspiration due to leaks around cuffs of endotracheal tubes. Anesteshia Analg ; :-0. Browning DH, Graves SA: Incidence of aspiration with endotracheal tubes in children. J Pediatr ; 0:- 0. McCleave DJ, Fisher M: Efficacy of high volume low pressure cuffs in preventing aspiration. Anaesth Intensive Care ; :-. Spray SB, Zuidema GD, Cameron JL: Aspiration pneumonia. Am J Surg ; :0-0. Young PJ, Rollinson M, Downward G, et al: Leakage of fluid past the tracheal tube cuff in

14 Page of 0 a benchtop model. Br J Anaesth ; :-. Young PJ, Blunt MC: Compliance characteristics of the Portex Soft Seal Cuff improves seal against leakage of fluid in a pig trachea model. Crit Care ; :-. Dullenkopf A, Gerber A, Weiss M: Fluid leakage past tracheal tube cuffs: evaluation of the new Microcuff endotracheal tube. J Intensive Care Med 0; :-.Higenbottam T, Payne J; Glottis narrowing in lung diseaese. AM Rev Respir Dis ; :-. Belafsky PC, Blumenfeld L, LePage A et al: The accuracy of the modified Evans blue dye test in predicting aspiration. Laryngoscope 0; :-. R Development Core Team. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN , URL 0. Vittinghoff E, Glidden DV, Shibolski SC et al: Regression Methods in Biostatistics: Linear, Logistic, Survival, and Repeated Measures Models. Springer, New York, 0. Crawley MJ: Statistics: an Introduction Using R. John Wiley & Sons Ltd, Chichester, 0. Glantz SA: Primer of Biostatistics. The McGraw-Hill Companies, New York, 0. Torres A, Serra-Batlles J, Ros E et al: Pulmonary aspiration of gastric content in patients receiving mechanical ventilation: The effect of body position. Ann Intern Med ; :0-. Janson BA, Poulton TJ: Does PEEP reduce the incidence of aspiration around endotracheal tubes? Can Anesth Soc J ; :-. Hahnel J, Treiber H, Konrad F et al: Vergleich verschiedener Endotrachealtuben. Trachealabdichtung, Spitzenzentrierung, und Inzidenz postoperativer Halsbeschwerden. Anaesthesist ; :-

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16 Page of 0 Table. Anthropometric data, clinical variables and causes for admission in ICU HL SG Number of patients Age, yrs.±..±. Height, cm.±..±. Weight, kg.±0..±. Tube size., mm i.d. 0 Tube size, mm i.d. 0 VT, ml ± ± RR, min.±..±. Subaracniodal Hemorrhage Cerebral neoplasia Mean and SD values where applicable. HL, group of patients intubated with Hi-Lo tracheal tube; SG, group of patients intubated with SealGurd tracheal tube (Mallinckrodt Medical, Cornamady, Athlone Country, Ireland both groups); VT, tidal volume; RR, respiratory rate; i.d., internal diameter.

17 Page of 0 LEGENDS FOR THE FIGURES Figure. Survival time plot of the percentage of leaking tubes as a function of time after intubation. Broken lines represent patients intubated with Hi-Lo tracheal tubes and solid lines pertain to those that received SealGuard tubes. The first leakage was detected in two patients of the Hi-Lo group at the th hour. PEEP ( cm H O) was then removed. One hour afterwards all the Hi-Lo patients presented fluid leakage past the cuffs. In the SG group the first microinhalation was detected at the th hr and at the end of the experiment ( hrs) patients were still sealed. There was a statistically significant difference in global behavior between the two groups of patients (P < 0 - ). Figure. Bronchoscopic image of the lower trachea and main bronchi in a patient presenting fluid leakage past the tracheal tube cuff as represented by the blue dye on the right. Figure. Two tracheal tubes (Hi-Lo on the left and SealGaurd on the right) with inflated cuffs ( cm H O) inside measuring cylinders (PEEP = cm H O) right after the application of Evans blue on the top of the cuffs. One can easily note dyed longitudinal folds within the cuff wall on the left tube. Figure. Two tracheal tubes (Hi-Lo on the left and SealGaurd on the right) with inflated cuffs ( cm H O) inside measuring cylinders (PEEP = cm H O) 0 min after the removal of PEEP ( min after the application of Evans blue on the top of the cuffs). One can easily note dyed longitudinal folds within the cuff wall on the left tube. All liquid passed around the left cuff. On the other hand no fluid leakage is seen on the SealGuard tube.

18 Page of 0 Figure. Survival time plot of the percentage of leaking tubes as a function of time after intubation. Broken lines represent patients intubated with Hi-Lo tracheal tubes and solid lines pertain to those that received SealGuard tubes. The first leakage was detected in two patients of the Hi-Lo group at the th hour. PEEP ( cm H O) was then removed. One hour afterwards all the Hi-Lo patients presented fluid leakage past the cuffs. In the SG group the first microinhalation was detected at the th hr and at the end of the experiment ( hrs) patients were still sealed. There was a statistically significant difference in global behavior between the two groups of patients (P < 0 - ).

19 Page of 0 Figure. Bronchoscopic image of the lower trachea and main bronchi in a patient presenting fluid leakage past the tracheal tube cuff as represented by the blue dye on the right.

20 Page of 0 Figure. Two tracheal tubes (Hi-Lo on the left and SealGaurd on the right) with inflated cuffs ( cm H O) inside measuring cylinders (PEEP = cm H O) right after the application of Evans blue on the top of the cuffs. One can easily note dyed longitudinal folds within the cuff wall on the left tube.

21 Page of 0 Figure. Two tracheal tubes (Hi-Lo on the left and SealGaurd on the right) with inflated cuffs ( cm H O) inside measuring cylinders (PEEP = cm H O) 0 min after the removal of PEEP ( min after the application of Evans blue on the top of the cuffs). One can easily note dyed longitudinal folds within the cuff wall on the left tube. All liquid passed around the left cuff. On the other hand no fluid leakage is seen on the SealGuard tube.