|Year : 2017 | Volume
| Issue : 3 | Page : 142-147
Value of automatic tube compensation in weaning of mechanically ventilated patients in medical ICU
Mohamed Abouzeid1, Ahmed E Kabil MD 2, Ahmed Al-Ashkar1, Hafez Abdel-Hafez1
1 Department of Internal Medicine, Al-Azhar University, Cairo, Egypt
2 Department of Chest Diseases, Al-Azhar University, Cairo, Egypt
|Date of Submission||30-May-2017|
|Date of Acceptance||26-Sep-2017|
|Date of Web Publication||22-Feb-2018|
Ahmed E Kabil
Department of Chest Diseases, Al-Azhar University, Cairo
Source of Support: None, Conflict of Interest: None
Automatic tube compensation (ATC) has been recently introduced to compensate for artificial airway resistance that may be beneficial during spontaneous breathing trials. It has been used as a mode of mechanical ventilation in some newer mechanical ventilators and as an add-on feature for the existing ventilation modes in some other ventilators.
To assess the expected value of ATC in the weaning process.
Patients and methods
A prospective randomized controlled study was conducted at the Medical ICU of Al-Hussein University Hospital, Cairo. Sixty mechanically ventilated patients were included during the period from September 2016 to June 2017. The patients were randomly divided into three groups: 20 patients were weaned by pressure support ventilation (PSV) plus ATC, 20 patients were weaned by PSV alone and 20 patients were weaned by ATC alone. The primary outcome measure was comparison between different groups in weaning outcomes and duration of weaning.
There was no significant difference between the three groups as regards demographic data, cause of admission or baseline characters at the start of randomization. The weaning duration of PSV+ATC group was significantly lower than the other groups. The duration of weaning in the ATC group was lower than that in the PSV group. There was a higher trend towards successful extubation in PSV+ATC group than other groups but without statistically significant difference. Mortality and morbidity were lower in PSV+ATC group than other groups and were lower in the ATC group than the PSV group but without statistically significant difference.
In medical ICU patients, the weaning process can be successfully performed by ATC as an add-on feature to the existing modes or as a separate mode. Duration of weaning, total duration of mechanical ventilation and duration of ICU stay were significantly lower with ATC.
Keywords: automatic tube compensation, medical ICU, pressure support ventilation, weaning
|How to cite this article:|
Abouzeid M, Kabil AE, Al-Ashkar A, Abdel-Hafez H. Value of automatic tube compensation in weaning of mechanically ventilated patients in medical ICU. Al-Azhar Assiut Med J 2017;15:142-7
|How to cite this URL:|
Abouzeid M, Kabil AE, Al-Ashkar A, Abdel-Hafez H. Value of automatic tube compensation in weaning of mechanically ventilated patients in medical ICU. Al-Azhar Assiut Med J [serial online] 2017 [cited 2018 Sep 23];15:142-7. Available from: http://www.azmj.eg.net/text.asp?2017/15/3/142/226047
| Introduction|| |
Weaning is the process of withdrawing mechanical ventilatory support and thus transferring the work of breathing from the ventilator to the patient himself. Weaning is a very critical step in the process of mechanical ventilation and still a great challenge. Weaning prolongation is related to increased mortality and morbidity . With the great advances in technology, new features on ventilators have been developed as automatic tube compensation (ATC) which may be a separate mode or as an add-on to other modes. Small trials have been done to evaluate weaning outcome using either this new mode or an add-on feature to traditional modes with promising results ,,,. With the passage of air through the artificial tube there will be a difference in pressure between the two ends of the tube and the patients’ respiratory system have to compensate for this pressure difference especially with spontaneous breathing trials (SBTs) and weaning. ATC acts by continuous calculations of the pressure difference between the two ends of the tube. This calculation is based on regular measurement of air flow, airway pressure difference (between both ends of the tube) and tube-specific coefficient . ATC works to compensate automatically for the pressure difference across the tube and delivering the exact amount of pressure needed to overcome this resistive load . On the other hand, tube obstructions as a result of secretions or kinking may cause undercompensated tube resistance with this feature ,. In recent studies, ATC has been shown to decrease the work of breathing used to overcome the resistive load of artificial airways more effectively than the traditional methods of weaning. It is assumed that it can mimic spontaneous breathing without the artificial airways, so it can be called (electronic extubation) . It is believed that ATC may decrease the weaning period and increase the probability of successful extubation .
The aim of the study was to evaluate the value of ATC either as a mode ventilation or as an add-on feature to other modes in the process of weaning.
| Patients and methods|| |
This prospective randomized controlled study was conducted from September 2016 to June 2017, in the Medical ICU of Al-Hussein University Hospital, Cairo. The study included 60 mechanically ventilated patients. An informed written consent was taken from a first-degree relative of every patient included in the study and the study was approved by the Ethics Committee for Research of the Faculty of Medicine, Al-Azhar University.
Adult patients who were endotracheally intubated, undergoing mechanical ventilation for at least 24 h and ready for weaning, according to our MICU’s ventilator weaning protocol that follows the current statement of ERS, ATS, ESICM, SCCM and SRLF .
Age less than 18 years, pregnancy, unplanned extubation either during or before the weaning process, death before becoming ready to wean or patients who have completed 7 days of mechanical ventilation without fulfilling the weaning criteria.
Initiation of mechanical ventilation
All included patients were intubated with endotracheal tube size 7–8. Mechanical ventilation was performed using Dräger Evita V300, Drägerwerk AG & Co., Lübeck, Germany. Patients were adjusted on synchronized intermittent mandatory ventilation, volume-controlled mode except for cases with adult respiratory distress syndrome where pressure-controlled ventilation was used with lung protective strategy.
All patients were receiving standard medical therapy. Sedation was achieved with midazolam and adjusted for each patient according to his or her need and stopped when the patient was ready for weaning.
Patients randomization and weaning
Weaning was decided after achievement of the weaning criteria of the guidelines of ERS, ATS, ESICM, SCCM and SRLF . Patients were randomly divided into three groups: group I included 20 patients who were weaned by ATC with pressure support ventilation (PSV+ATC), group II included 20 patients who were weaned by PSV alone, group III included 20 patients who were weaned by ATC alone.
The weaning protocol for the three groups:
Weaning from mechanical ventilation (MV) was decided as early as possible with a daily screen for the assessment of readiness to wean. SBT was performed early in the morning. The SBT was performed with either PSV, ATC or PSV+ATC. In all groups, the ventilator parameters were adjusted as the following: the peak end expiratory pressure at 0–5 cmH2O with FiO2 less than or equal to 0.4. In the PSV+ATC group (20 patient), initial positive pressure support (PS) was set at 15 cmH2O. Patients were extubated at a PS of 8 cmH2O and in the same situation the size of the tube was entered into the ventilator software and inspiratory ATC set at 100%. For the patients weaned by PSV only (20 patients), initial positive PS was set at 15 cmH2O. PS was gradually lowered by 2–4 cmH2O. Extubation was done at a PS of 8 cmH2O (which is suggested to be equal to tube resistance). In the ATC group (20 patients), the size of the tube was entered into the ventilator software and inspiratory ATC set at 100%. PS was adjusted at zero (the type of ventilators used in current study has only ATC as an add-on feature to other modes, so we used PS with ATC and set PS at zero to equal the ATC mode only in other types of ventilators). If the first SBT failed, all subsequent SBTs were done with the same SBT method.
Patients were closely observed during SBT. The signs of successful SBT include a good breathing pattern with patient comfort, successful gas exchange and haemodynamic stability . Failure of SBT was considered with any of the following: increased respiratory rate more than or equal to 35 breaths/min, fall of oxygen saturation to less than 90%, rise of heart rate more than 140 beats/min or a sustained rise or decrease in the heart rate of more than 20% of that before starting SBT. Decreased systolic blood pressure of less than 90 mmHg or rise of more than 180 mmHg, agitation or diaphoresis, hypercapnia with increased level of PaCO2 more than 20% from the previous value or deterioration of the conscious status and psychomotor agitation .
With success of SBT, extubation was done, while with its failure mechanical ventilation (by the previous same mode) was regained.
Weaning success: defined as independence from mechanical ventilation (either invasive or noninvasive) for at least 48 h after extubation. Weaning failure was considered with any one of the following: failure of SBTs for a period that necessitate tracheostomy (once the patient completed 2 weeks of intubation), reintubation and/or resumption of MV within 48 h of extubation, death during the weaning process or within 48 h of extubation .
Length of ICU or hospital stay: the time from admission to the ICU or the hospital until discharge or death. Complications related to MV such as VAP, pneumothorax.
The following data were collected from all groups to be statistically analysed and compared: demographic data (age, sex and BMI), APACHII, haemodynamic parameters (heart rate, respiratory rate and mean arterial blood pressure) before randomization and before successful extubation, ventilator parameters 1 h after randomization and before successful extubation (FiO2, peak airway pressure, tidal volume, RR and minute ventilation) which were considered as the mean of three successive breath cycles at least, arterial blood gases (ABGs) before randomization, 1 h after randomization and before successful extubation, duration of weaning, duration of mechanical ventilation, length of ICU stay, length of hospital stay, complications including VAP, pneumothorax, arrhythmia, and deaths.
The collected data were organized, tabulated and statistically analysed using SPSS software statistical computer package version 16. For qualitative data, frequency and percent of distribution were calculated and for comparison between groups, χ2-test was used. For quantitative data, mean, SD and sometimes, median, minimum and maximum were calculated. The (one-way analysis of variance test) was used for comparison between normally distributed quantitative variables, and when P-value up to 0.05 (Tukey–Kramer test) was used for multiple comparison between groups. Kruskal–Wallis nonparametric test was used for comparison between abnormally distributed quantitative variables, and when P-value up to 0.05, Dunn’s multiple comparisons test was used for multiple comparisons between groups. For interpretation of results, P-value up to 0.05 was considered statistically significant.
| Results|| |
There was no statistically significant difference between the studied groups with regard to age, sex distribution, BMI or APACHII score at admission ([Table 1]).
|Table 1 Demographic data and baseline difference between the studied groups|
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There was no statistically significant difference between the studied groups immediately before weaning trial as regards ABGs and vital signs ([Table 2] and [Table 3]).
Apart from tidal volume and peak inspiratory pressure, there was no statistically significant difference between the ventilatory parameters of the studied groups 1 h after weaning trial ([Table 4],[Table 5],[Table 6]).
|Table 4 Comparison between the ventilatory parameters of studied groups 1 h after weaning trial|
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|Table 5 Comparison between the arterial blood gases parameters of studied groups 1 h after weaning trial|
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| Discussion|| |
ATC is a recently developed mechanical ventilatory support method to overcome endotracheal tube resistance. It is used as a mode of ventilation in some ventilators, while in others it is used as an add-on feature to other modes. PSV is a common mode for weaning from mechanical ventilation. It generates a constant pressure that assists patient effort throughout the inspiratory period ,. In this prospective controlled trial, 60 patients were recruited with the aim of the comparing ATC with PSV in weaning of different diseases. Patients were divided into three groups: group I included 20 patients who were weaned by ATC PSV+ATC; group II included 20 patients who were weaned by PSV alone; group III included 20 patients who were weaned by ATC alone; all patients were ready for weaning after improvement of general conditions and gas exchange. In the present study, there was no statistically significant difference in the age of the studied groups. Also, there was no statistically significant difference in sex distribution and BMI between the studied groups, with predominant male sex in each group.
Moreover, there was no significant difference between the studied groups in mean APACHE II score at the time of ICU admission or because of mechanical ventilation.In addition, there was no statistically significant difference in vital signs and ABGs of the studied groups before starting weaning trial and randomization.
So, there were no significant differences in baseline characteristics between the studied groups. So, we can suggest that the three methods of weaning (PSV+ATC, PSV and ATC) can be conveniently compared with each other as regards weaning progression and outcome and also length of stay, the occurrence of complications and mortality rate .
In the current study, the ventilatory parameters of the studied groups one hour after randomization showed statistically significant decrease in the peak inspiratory pressure and the tidal volume of the PSV+ATC group than other groups. Apart from the peak inspiratory pressure and tidal volume, there was no statistically significant difference between the studied groups of the current study in other ventilatory parameters 1 h after randomization. Moreover, the ABG parameters in the current study showed a statistically insignificant difference between the studied groups 1 h after randomization. These results are consistent with Figueroa-Casas and colleagues who posted that RR/TV ratio and PaO2/FiO2 had no significant difference between the ATC group and the CPAP group. Selek and colleagues reported that there is no significant difference as regards respiratory rat and SaO2 over the course of the study period between ATC and T-piece. On the other hand, Haberthur and colleagues stated that there were significant differences between both groups in respiratory rate, tidal volume and RR/TV ratio .
Before starting weaning in the current study, there was no statistically significant difference between the studied groups in the duration of mechanical ventilation. The weaning duration of the PSV+ATC group was significantly lower than the ATC group and that of the ATC group was lower than the PSV group (but statistically insignificant).
In agreement with our results, Aggarwal and colleagues concluded that the duration of weaning was significantly shorter in the PSV+ATC group than in the PSV group in patients with severe neuroparalytic snake envenomation .
In addition, Figueroa-Casas and colleagues reported a nonsignificant trend towards shorter duration of weaning trials with ATC than PSV .
Moreover, Selek and colleagues found weaning duration to be significantly shorter in ATC versus T-piece.
Despite significant shortening in the duration of mechanical ventilation of PSV+ATC group than ATC and PSV groups in the current study, the length of ICU stay and the duration of hospital stay did not differ significantly among the studied groups.
In the current study, weaning success was achieved in 14 (70%) patients of PSV+ATC group, 13 (65%) patients of ATC group and 12 (60%) patients of the PSV group, without statistically significant difference among the studied groups in the outcome of weaning.
Comparable to the results of the present study, El-Shahat and colleagues who studied 166 mechanically ventilated patients ready for weaning, comparing ATC mode with PSV mode: there was no statistically significant difference between the studied groups in weaning success which was achieved in 69 (78.4%) patients of the PSV group and 69 (88.5%) patients of the ATC group, without statistically significant difference among the studied groups in the outcome of weaning. Also these results were consistent with Haberthur and colleagues and Figueroa-Casas and colleagues, who concluded nearly the same result with different numbers .
Mortality and morbidity were lower in PSV+ATC group than other groups and were lower in the ATC group than in the PSV group. However, there was no statistically significant difference among the studied groups of the current study in the rate of mortality and the complications related to mechanical ventilation. These results are consistent with El-Shahat and colleagues who concluded a nonsignificant decrease in mortality and complications with ATC .
The main limitations of our study are the low number of patients included and it was a single centre study. So large multicentre studies are recommended for further evaluation of ATC either as an add-on feature or as a separate mode in the process of weaning of mechanically ventilated patients.
| Conclusion|| |
According to the current study results, we can conclude that in a medical ICU population, ATC (either as an add-on feature or as a separate mode) was safe, efficient and can be successfully used for weaning. It has a potential benefit in weaning duration, extubation outcome, ICU length of stay, complications and mortality rate. So, ATC may be a valuable add-on feature or mode for use during the process of weaning of mechanically ventilated patients.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]