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Year : 2019  |  Volume : 32  |  Issue : 2  |  Page : 423-429

Noninvasive versus invasive ventilation in weaning of patients with type 2 respiratory failure

1 Department of Anesthesiology and Intensive Care, Faculty of Medicine, Minoufia University, Minoufia, Egypt
2 Department of Chest, Faculty of Medicine, Minoufia University, Minoufia, Egypt
3 Department of Critical Care, Ahmed Maher Teaching Hospital, Minoufia, Egypt

Date of Submission06-Nov-2017
Date of Acceptance17-Dec-2017
Date of Web Publication25-Jun-2019

Correspondence Address:
Mahmoud NZ Ghoneum
Shibin El Kom, Menoufia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mmj.mmj_749_17

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The aim of this study was to investigate noninvasive ventilation (NIV) effectiveness as an early weaning technique in difficult-weaning patients with chronic hypercapnic respiratory failure.
Although invasive ventilation is effective, it is associated with complications like ventilator-associated pneumonia. Ventilator-associated pneumonia has been associated with increased morbidity and mortality. So, minimizing the duration of invasive mechanical support without increasing the risk of adverse events is an important goal. NIV may provide a means of reducing the duration of invasive mechanical support for patients with respiratory failure.
Patients and methods
A prospective, randomized controlled study was conducted on 40 mechanically ventilated patients having chronic obstructive pulmonary disease with acute exacerbation and type 2 respiratory failures. As the patients were considered for weaning, those who failed the spontaneous breathing trial were randomly allocated into two groups each of 20 patients as follows: (1) Group 1: patients were extubated and received NIV. (2) Group 2: patients received invasive ventilation and were gradually weaned.
There was no statistically significant difference between the two groups in invasive ventilation-free days at day 28 (P = 0.885), mechanical ventilation period (P = 0.688), weaning duration in hours (P = 0.578), ICU stay (P = 0.427), and 28-day survival rate (P = 0.518). Although there were a higher number of complications in group 1 compared with group 2, the difference was statistically insignificant.
NIV has no upper hand in weaning of difficult-weaning patients with chronic hypercapnic respiratory failure over invasive ventilation.

Keywords: chronic obstructive pulmonary disease, noninvasive ventilation, survival rate, ventilator weaning

How to cite this article:
Afifi MH, Fathy YI, El_Dahdouh SS, Ghoneum MN. Noninvasive versus invasive ventilation in weaning of patients with type 2 respiratory failure. Menoufia Med J 2019;32:423-9

How to cite this URL:
Afifi MH, Fathy YI, El_Dahdouh SS, Ghoneum MN. Noninvasive versus invasive ventilation in weaning of patients with type 2 respiratory failure. Menoufia Med J [serial online] 2019 [cited 2020 May 27];32:423-9. Available from: http://www.mmj.eg.net/text.asp?2019/32/2/423/260916

  Introduction Top

Chronic obstructive pulmonary disease (COPD) is one of the most common causes of morbidity and mortality worldwide, so many attempts have been made to reach better diagnosis and management modalities in patients with COPD[1].

COPD exacerbation represents a part of the common course of the disease, which is characterized by worsening of the patient's baseline difficulty in breathing, cough, and/or sputum sufficient to intensify management[2].

Mechanical ventilation (MV) because of acute respiratory failure in patients with COPD is associated with high rates of ICU mortality (37–64%)[3].

The reason for increased use of noninvasive ventilation (NIV) is to avoid adverse effects of invasive ventilation in patients with COPD. Although invasive MV is very trustable, effective, and dependable in supporting alveolar ventilation, endotracheal intubation carries common dangerous problems[4],[5].

NIV has advantage of ventilatory support without invading airway by synthetic process (an endotracheal tube or a tracheostomy tube) as it delivers ventilation through an interface facial or a nasal mask[6].

NIV has the advantages of increasing tidal volume, reducing respiratory rate, relaxation of the muscles of respiration, and also hastening of gas exchange[7].

Aiming to decrease invasive ventilation side effects, researchers have studied the NIV as a mode of weaning by replacing invasive support with noninvasive support in patients who are ready to be weaned off but not yet ready for MV to be removed. The incidence of the complication of invasive ventilation compared with noninvasive is decreased owing to many factors[8],[9].

However, with noninvasive weaning (NIV), clinicians must suspect drying of secretions and expect that only partial ventilatory support can be achieved, and also complete safety of airway is not accomplished[10].

The purpose of this study was to further assess the effectiveness of NIV as a new modality for weaning of patients with COPD from MV. Compared with the traditional gradual weaning, NIV was assessed regarding invasive ventilation-free days at day 28, MV period, weaning duration in hours, ICU stay, and 28-day survival.

  Patients and Methods Top

A prospective randomized controlled study was conducted in ICU on 40 MV patients having COPD with acute exacerbation and type 2 respiratory failures from January 2016 to April 2017. Informed consent was obtained from the closest relative of each patient. This study was approved by the research ethics committee, Faculty of Medicine, Quality Assurance Unit.

All ICU patients underwent daily screening during the morning round. A total of 40 patients with COPD with acute exacerbation who were on MV for 48 h or more and failed at 30 min of spontaneous breathing T piece trial (SBT) were included in this study.

Our exclusion criteria were patients with cardiogenic pulmonary edema, pregnancy, relatives or patient's refusal, and also contraindications for using NIV like cardiac or respiratory arrest, severe encephalopathy (Glasgow coma scale <10), active upper gastrointestinal tract bleeding, recent gastric or esophageal surgery, hemodynamic instability or severe arrhythmia, facial surgery or trauma or deformity, severe upper airway obstruction, and inability to cooperate or protect airway (inability to cough or clear respiratory secretions and absence of a gag reflex).

Our inclusion criteria were patients with COPD experiencing acute on top of chronic respiratory failure, age greater than or equal to 18 years, PaCO2 greater than or equal to 50 mmHg at time of intubation, and the period of invasive MV of 48 h or more.

All patients were initially ventilated with control/assist control mode; intubation was done through the orotracheal route. Sedation was used as required. With the endotracheal tube in place, patients were evaluated on a daily basis for readiness to weaning using SBT on T piece.

After the patients underwent SBT and failed, all 40 patients were returned to invasive MV until hemodynamics and arterial blood gas (ABG) parameters returned to values before SBT, and then random allocation of patients was done using opaque sealed envelopes (we made 40 opaque envelopes and wrote in them generated treatment allocation as 20 for noninvasive weaning and 20 for invasive weaning, and then we sealed the envelops. Once a patient was consented to enter a trial, an envelope was opened, and the patient was then offered the allocated treatment regimen) into one of two groups.

Group 1 (20 patients) were extubated and received NIV, using ventilators (Drager EVITA 4 Drägerwerk AG & Co. KGaA, Moislinger Allee 53–55, 23558 Lübeck with dedicated software for NIV application) in pressure support ventilation (PSV) mode. Patients received NIV through an oronasal mask continuously except during meals and for expectoration. As soon as we could reduce the inspiratory positive airway pressure and expiratory positive airway pressure levels to 10 and 5 cm H2O, respectively, with satisfactory ABG parameters, arterial oxygen saturation (SaO2) greater than or equal to 90% on FiO2 40%, and RR less than 30/min, patients were allowed to breathe spontaneously. Weaning from NIV was performed on a daily basis by gradually reducing pressure levels until adequate VT and Ve levels were reached and proper alveolar ventilation can be established. Afterward, NIV was withdrawn and oxygen was administered by venturi mask. When NIV failed, reintubation was done.

Group 2 (20 patients, control group) patients received invasive PSV with an initial level of pressure support to achieve acceptable ABG parameters, RR less than 30/min, and patient's tolerance and comfort. Subsequently, the pressure support was decreased by 2 cm H2O every 4 h with close monitoring for worsening of SaO2 and relative risk (RR). When the pressure support and positive end expiratory pressure reached 10 and 5 cm H2O, respectively, with satisfactory blood gases, stable vitals, SaO2 greater than or equal to 90% on FiO2 40%, RR less than 30/min, and absence of severe dyspnea/depressed sensorium, patients were extubated and allowed to breathe spontaneously on a venturi mask.

Criteria for extubation for both groups were adequate cough reflex and gag reflex, the patient can protect his/her airways, secretions are not copious, done in the morning, and cuff leak greater than 110 ml during assisted controlled ventilation, indicating that the patient is unlikely to develop stridor or airway obstruction after extubation[11].

Patients were immediately reintubated if there was one of the following criteria: cardiac or respiratory arrest, agitation not adequately controlled by sedation, respiratory pauses with loss of consciousness or gasping for air, massive aspiration, persistent inability to remove respiratory secretions, heart rate (HR) below 50 beats/min with loss of alertness, and hemodynamic instability with no response to fluids and vasoactive drugs.

Extubation failure was defined by the inability to sustain spontaneous unassisted breathing for 48 consecutive hours, without developing respiratory failure requiring ventilatory support (either invasive or noninvasive). In addition to reintubation criteria, both groups were monitored for signs of respiratory failure, which are respiratory acidosis [pH (potential of hydrogen) ≤7.35 with PaCO2 (carbon dioxide partial pressure) ≥ accepted value for patients with COPD], arterial O2 saturation by pulse oximetry less than 85%, RR exceeding 30 beats/min, decreased consciousness, agitation, or diaphoresis, respiratory muscle fatigue evidenced by use of accessory muscles of respiration, intercostal spaces retraction, and paradoxical movement of the abdomen.

In the NIV group, if a patient developed respiratory failure after 24 h, we reinstituted the NIV and follow-up him/her for 2 h; if no improvement was seen, we reintubated him, and if improvement was seen, we continue for 4 h.

In the control group, if the patient develops respiratory failure, we will put him/her on NIV and follow up for 2 h. If no improvement was seen, we intubate immediately, and if improvement was seen, we continue NIV for 4 h.

Data collection

Patient data such as age, sex, Acute Physiology and Chronic Health Evaluation (APACHE-II) score on admission, duration of MV (days) before randomization, underlying disease, and cause of MV was collected.

Before SBT, the following measurements were carried out: ABGs; ventilatory parameters such as respiratory rate (f), tidal volume VT, minute ventilation (Ve), peak inspiratory pressure, positive end expiratory pressure, and fraction of inspired oxygen (FiO2); f/VT; HR; systolic blood pressure (SBP); diastolic blood pressure (DBP); and SaO2.

At 1 min and 30 min of spontaneous ventilation trial, the following parameters were measured: f, VT, Ve, rapid shallow breathing index (f/VT), HR, SBP, and DBP. If failure occurred before the 30th minute, f, HR, SpO2, and SBP and DBP were measured at the time of failure. If the patient failed SBT, he/she was included in either group by random assignment. Patients in the experimental group were extubated and placed on NIV, whereas the other patients (the control group) returned to invasive mechanical ventilation (IMV), which was classified as the conventional treatment. The group on NIV (the experimental group) was extubated after having rested in the MV for 30 min in the experimental group. Immediately after tracheal extubation, spontaneous ventilation mode was initiated using a bi-level NIV support unit. Inspiratory positive airway pressure was delivered according to patient tolerance and varied from 10 to 20 cm H2O.

All patients were assessed by the following: ABG analysis (ABG was performed before SBT and at first minute, 30 m of SBT, and before 30 m if failed SBT, and in first, second, fourth, and eighth hour during the weaning process. Arterial blood samples were collected from each patient by the use of disposable sterilized plastic syringe), Glasgow coma scale (it was assessed before SBT as a weaning parameter), the rapid shallow breathing index as a weaning parameter was measured at the start of SBT), duration of weaning in hours (duration started in group one after extubation and receiving NIV, whereas in group 2, after return of ABG to normal values after reconnecting the patients of these group to invasive MV), duration of ICU stay (from the day of admission to the day of discharge from ICU), ICU mortality rate after 28 days, incidence of complication (sepsis, nosocomial pneumonia, and ventilator-associated pneumonia), complications related to mode of ventilation, incidence of tracheostomy, and incidence of septic shock.

Statistical analysis

The collected data were organized, tabulated, and statistically analyzed using SPSS software (statistical package for the social sciences, version 13, SPSS Inc., Chicago, Illinois, USA). For qualitative data, comparison between two groups and more was done using χ2-test, paired t-test, and the mean and SD. Significance was adopted at P value of less than 0.05 for interpretation of results of tests of significance.

  Results Top

A total of 130 patients with COPD with type 2 respiratory failure were admitted in the ICU during the period of study. A total of 30 patients were intubated and MV from the start whereas remaining hundred patients were managed initially with noninvasive positive pressure ventilation. Overall, 65 of them were successfully managed with noninvasive positive pressure ventilation and were not included in our study, whereas the remaining 35 patients were intubated and MV, so a total of 65 patients were intubated and MV. Ten patients died after intubation. Of the remaining 55 patients, 15 patients were excluded from the study after being successfully weaned after SBT, so remaining 40 patients were randomly allocated into the two study groups [Figure 1].
Figure 1: A flow chart showing patients included in this study. MV, mechanical ventilation; NIV, noninvasive ventilation.

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The general demographic data and baseline characteristics (age, sex, and weight) of the enrolled patients in both groups showed no statistical significant difference (P = 0.417, 0.114, and 0.763, respectively). Moreover, APACHE-II on admission showed no significant difference between both groups (P = 0.701) [Table 1].
Table 1: Demographic data of the two groups

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Weaning failure during SBT was 72.7% (40/55). Regarding duration of invasive MV before randomization, there was no significant difference between the two groups (P = 0.138) [Table 2].
Table 2: Duration of invasive mechanical ventilation before randomization

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There was significantly difference between the two groups in comorbidities (in diabetes mellitus and ischemic heart disease). More number of patients in group 1 had diabetes mellitus (P = 0.027(whereas group 2 had more patients with ischemic heart disease (P = 0.018). Other comorbidities such as hypertension, hepatitis c virus, atrial fibrillation, and renal impairment did not show any significant difference (P = 0.311, 0.292, 0.077, and 0.072, respectively) [Table 3].
Table 3: Comorbidities of two groups

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There was no significant difference between the two groups regarding reasons of reintubation (P = 0.406) [Table 4].
Table 4: Reasons for reintubation according to study group

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Although a higher number of complications (septic shock, nosocomial pneumonia, skin necrosis, other complication, and return to MV) were present in group 1 compared with group 2, the difference was statistically insignificant (P = 0.429, 0.429, 0.311, 0.256, and 0.465, respectively). Moreover, the incidence of tracheostomy had no significant difference between the two groups (P = 0.376) [Table 5].
Table 5: Incidence of complication in two groups

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There was no statically significant difference between two groups in invasive ventilation-free days at day 28 MV period, weaning duration in hours, ICU stay, and 28-day survival (P = 0.885, 0.688, 0.578, 0.427, and 0.212, respectively) [Table 6].
Table 6: Outcomes of two groups

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  Discussion Top

In spite of the strong evidence that supports the use of NIV to replace invasive MV to reduce complication of intubation and thus reducing mortality and improving outcome[12],[13],[14],[15], this is more evident in certain patient population, for example, patients with COPD with acute exacerbation, and has been proven by previously conducted randomized controlled trials[12],[16],[17]. However, its use as an alternative for early weaning extubation remains controversial[18].

In the present study, we were not able to find out an advantage of NIV over conventional way of weaning. Both groups were similar regarding 28-day mortality, ICU length of stay, duration of invasive MV, and complications of MV, as there was no statistically significant difference.

Patients of both groups showed statistically insignificant difference in demographic data (age, sex, and weight), APACHE-II score on admission, duration of MV before randomization, and comorbidities.

Weaning failure during SBT was 72.7% (40/55), which is higher than that reported in the literature, which ranged from 35 to 67%[19].

This finding could be explained by the relatively more critical general condition as expressed by high APACHE-II score on admission.

The duration of weaning in hours was less in NIV group compared with invasive group (51 ± 32.6 vs. 55 ± 9.8); however, that difference was statistically insignificant.

In consistence with the present study, Prasad et al.[20], who studied the role of NIV in weaning from MV in patients with COPD in a prospective, randomized, controlled study, where patients (n = 30) were randomized to receive either NIV or PSV as a weaning method from MV, observed no significant statistical difference between the two groups regarding the duration of ventilation, weaning hours, ICU stay, and mortality.

However, in contrast to the present study, some other studies[21],[22],[23] reported shorter duration of weaning when using NIV compared with invasive MV with an expected finding, but Burns KE et al.[23], who randomized 208 intubated patients with COPD into three groups, that is, NIV, conventional invasive group, or extubation followed by standardized oxygen therapy, found that NIV is associated with longer weaning duration compared with invasive group (2.5 vs. 1.5 days), but in line with our study, they found no difference in reintubation rate between the three weaning strategies.

In the present study, the number of complication was less in NIV group; however, the difference was statistically insignificant. The most common complication was nosocomial pneumonia in 20% and septic shock in 20%. Some studies[23],[24],[25] stated that there was significant reduction in complication rate when using NIV for weaning compared with invasive MV. In agreement with our study, Girault et al.[26] reported that there was no difference in complication rate between both NIV and conventional weaning method.

In the present study, NIV group had shorter ICU length (16 ± 5.3 vs. 18.35 ± 10.69), although this difference was not statistically significant. Moreover, in consistence with our study, Girault et al.[18] and Esteban et al.[27] found no difference between two groups in ICU stay; however, Nava S et al.[25], Trevisan et al.[24], and Burns et al.[23]demonstrated appositive effect of NIV on ICU length of stay, as it shortened ICU stay.

We did not observe any reduction in mortality rate, as did Esteban et al.[27] and Girault et al.[18];however, some studies contradicted our result[23].

Limitation of our study is that the sample size was relatively small, no further data were collected after 28 days, and our study was conducted on selected group of patients (patients with COPD). There is a need for further investigation on other patients groups, and cost evaluation should also be included, especially in limited-resource countries like Egypt.

  Conclusion Top

The results of this study failed to find out any advantage of NIV as a weaning modality to replace invasive conventional method. However, further investigations are required with larger sample size with special consideration on cost evaluation.

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Conflicts of interest

There are no conflicts of interest.

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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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