Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 7  |  Issue : 1  |  Page : 76-79

Difficult weaning from mechanical ventilation in the pediatric ICU


Department of Pediatrics, Zagazig University, Zagazig, Egypt

Date of Submission04-Aug-2013
Date of Acceptance15-Sep-2013
Date of Web Publication31-May-2014

Correspondence Address:
Mohamed Abdo
MD, Department of Pediatrics, Zagazig University, Gezeret Alsaada post office, Sharkia governerate, Zagazig
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-7934.128423

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  Abstract 

Background
Respiratory disorders are the main cause of respiratory failure in children. Insufficient alveolar ventilation results in hypoxemia and hypercapnia, which contribute to further depression of ventilation, resulting in respiratory failure. Although most patients wean from mechanical ventilation with little difficulty, some patients are unable to maintain sustained efforts of breathing for long periods and develop signs of fatigue. A failed weaning is defined as either the failure of spontaneous breathing trial or the need for reintubation within 48 h after extubation.
Objective
This study was undertaken to identify the causes of difficult weaning from mechanical ventilation and predict the variables responsible for this difficulty.
Participants and methods
A prospective study was performed on 100 children, comprising 59 boys and 41 girls. Their ages ranged between 2 months and 10 years. All the children were subjected to a detailed medical history taking, clinical examination, and laboratory investigations (complete blood count, serum electrolytes, and arterial blood gas). Patients were selected to participate in this study on the basis of the inclusion and exclusion criteria.
Statistical analysis
The Mann-Whitney U-test and the χ2 -test were used for statistical analysis.
Results
Among the 100 studied patients, 86 (86%) succeeded in being weaned from mechanical ventilation, whereas the remaining 14 patients (14%) failed to wean. This group included nine children who experienced difficulty in weaning and five children with prolonged weaning. Patients who were successfully weaned spent statistically less time on mechanical ventilation, had lower PaCO 2 , and lower bicarbonate level compared with patients who failed to wean (P = 0.002, 0.001, 0.04, respectively). There was no association between clinical diagnosis, hematological parameters, serum electrolytes, and weaning success.
Conclusion
We conclude that patients who were successfully weaned were statistically older, spent less time on mechanical ventilation, had lower PaCO 2 and FiO 2 , and lower bicarbonate level compared with those who failed to be weaned. We did not find a significant relation between the clinical diagnosis, hematological parameters, serum electrolytes, and weaning success.

Keywords: Difficult weaning, mechanical ventilation, spontaneous breathing trial


How to cite this article:
Abdo M, Talat MA, Zamzam SM. Difficult weaning from mechanical ventilation in the pediatric ICU. Ain-Shams J Anaesthesiol 2014;7:76-9

How to cite this URL:
Abdo M, Talat MA, Zamzam SM. Difficult weaning from mechanical ventilation in the pediatric ICU. Ain-Shams J Anaesthesiol [serial online] 2014 [cited 2021 Oct 25];7:76-9. Available from: http://www.asja.eg.net/text.asp?2014/7/1/76/128423


  Introduction Top


Respiratory disorders are the main cause of respiratory failure in children. Insufficient alveolar ventilation results in hypoxemia and hypercapnia, which contribute to further depression of ventilation causing respiratory failure. The average pediatric ICU has about 30% (range 20-64%) of its patients mechanically ventilated for a mean of 5-6 days [1]. Although mechanical ventilation is often life saving, it can be associated with complications such as ventilator-induced lung injury, nosocomial pneumonia, and cardiovascular instability from positive pressure ventilation [2],[3].

Although most patients wean from mechanical ventilation with little difficulty, some patients are unable to maintain sustained efforts of breathing for long periods and develop signs of fatigue. A failed weaning is defined as either the failure of a spontaneous breathing trial (SBT) or the need for reintubation within 48 h after extubation [4]. Failure of SBT is defined by: (a) objective indices of failure, such as tachypnea, tachycardia, hypertension or hypotension, acidosis, hypoxemia, and arrhythmia; and (b) subjective indices such as agitation, distress, depressed mental status, diaphoresis, and evidence of increasing respiratory effort [5]. A failed weaning trial may induce significant cardiopulmonary distress and requires re-establishing the patient by ventilation support without delay [6].


  Objective Top


This study was undertaken to identify the causes of difficult weaning from mechanical ventilation and predict the variables responsible for this difficulty.


  Participants and methods Top


Study population and sample size

This prospective study was performed on 100 children and comprised 59 boys and 41 girls. The results were calculated using the EPI-INFO 6 (By CDC, Atlanta, Georgia, USA) statistical package with the prevalence rate of extubation failure of 47%, as reported by Esteban et al. [7] in their study on 893 patients admitted to the pediatric ICU at the children's Hospital, Zagazig University, Egypt, in the year 2010-2011 at 95% confidence level and 80% power. The ages of the patients in this study ranged between 2 months and 13 years. These children had been admitted to the pediatric ICU at the children's Hospital, Zagazig University, Egypt, during the period from October 2011 to February 2013. All children included in this study were subjected to the following: careful history taking, clinical examination, and routine laboratory investigations (complete blood count, serum electrolytes, and arterial blood gas). Patients were selected to participate in this study on the basis of the following criteria:

  1. Inclusion criteria : on mechanical ventilation for 24 h or more and ready to undergo extubation according to the eligibility criteria on the basis of the judgment of the attending physician.
  2. Exclusion criteria : having undergone a tracheostomy, having neuromuscular disease, being of an estimated gestational age less than 37 weeks, and presence of known upper airway obstruction.


According to the results of the weaning trials, the patients were divided into three groups [8]:

  1. The simple weaning group : This group comprised patients tolerant to the first SBT and who were successfully extubated.
  2. The difficult weaning group : This group comprised patients who failed to tolerate the first SBT, could be successfully weaned only after three SBTs, or who required up to 7 days from the first SBT to be successfully weaned.
  3. The prolonged weaning group : This group comprised patients who had failed at least three SBTs or who required more than 7 days from the first SBT to be successfully weaned.


SBT is a standardized direct assessment of the ability of a patient to tolerate unassisted breathing.

Eligibility criteria comprising clearly defined clinical parameters were used to determine whether the patient could undergo a SBT. These criteria included:

  1. Improvement or resolution of the underlying cause of acute respiratory failure.
  2. Adequate gas exchange indicated by a PaO 2 level greater than 60 mmHg while breathing with FiO 2 concentration of 0.4 or lower with no need for increased ventilator support in the previous 24 h.
  3. Core body temperature lower than 38.5 C.
  4. Alert mental status after removal of sedative agents.
  5. Hemoglobin level greater than 10 g/dl.


The duration of SBT is commonly limited to a minimum of 30 min and a maximum of 2 h.

Tolerance of spontaneous breathing trial

Poor tolerance to SBT is determined by standardized criteria that include the following:

  1. Respiratory rate greater than the 90th percentile for age.
  2. Signs of increased respiratory work.
  3. Diaphoresis.
  4. Heart rate greater than the 90th percentile for age.
  5. Change in mental status.
  6. Blood pressure less than the third percentile for age.
  7. Pulse oximetry less than 90%.
  8. PaCO 2 greater than 50 mmHg or arterial pH less than 7.30.


Failure of SBT is defined by objective and subjective indices of failure and extubation failure is defined as the need to reinsert an artificial airway within 48 h following a planned removal of the endotracheal tube [9].

Statistical analysis

The data of the study were statistically analyzed by the statistical program for social science, version 15 (SPSS Inc., IBM, Chicago, USA). Data were expressed in the form of mean and SD or as count and percentage. Numerical data were compared using the Mann-Whitney U-test, whereas categorical data were compared using the χ2 -test. A P-value less than 0.05 was considered statistically significant.


  Results Top


Among the 100 studied patients, 86 (86%) succeeded in being weaned from mechanical ventilation, whereas the remaining 14 patients (14%) failed to wean. This group included nine children who experienced difficulty in weaning and five children with prolonged weaning. The relation of weaning success to demographic characteristics, duration of mechanical ventilation, and clinical and laboratory parameters is presented in [Table 1] and [Table 2].{Table 1}{Table 2}

[Table 1] shows that patients with successful weaning were statistically older and spent less time on mechanical ventilation compared with those who failed weaning.

[Table 2] shows that FiO 2 , PaCO 2 , and HCO 3 could predict weaning success in the studied patients.


  Discussion Top


Weaning of patients from mechanical ventilation should be planned according to clearly defined clinical and physiological criteria. It is important to assess the different factors that may predict the outcome of weaning. This will be useful to shorten the duration of mechanical ventilation, reduce the risk of reintubation, improve the outcome, and provide clearer weaning guidelines [9].

Hence, the present study aimed at identifying the causes of difficult weaning from mechanical ventilation and predict the variables responsible for this difficulty.

This study was performed on 100 children, comprising 59 boys and 41 girls. Their ages ranged between 2 months and 13 years with a mean age of 22.6 ± 37.2 months.

Among the 100 studied patients, 86 (86%) succeeded in being weaned from mechanical ventilation, whereas the remaining 14 patients (14%) failed to wean. This group included nine children who experienced difficulty in weaning and five children with prolonged weaning.

The figure of 14% for extubation failure lies midway between the 10.0% rate found by Kurachek et al. [10], who aimed to determine the rate of extubation failure, risk factors, and consequences of extubation failure in 2794 patients in pediatric ICUs, and the 20.0% rate found by Randolph et al. [11]. It was also very close to the rate found by Johnston et al. [12],[13] who evaluated the demographic characteristics, mechanical ventilation parameters, and blood gas values as predictors of extubation failure in 40 infants with severe acute broncholitis and reported an extubation failure rate of 15%. However, the rate of failure may be as high as 29% among higher risk infants and children [9].

In a recent study, a failure rate of 38.7% was reported in a series of 202 critically ill pediatric patients who received mechanical ventilation [14].

As regards the relation of weaning to demographic characteristics, the present study has revealed that patients with successful weaning were statistically older (and consequently heavier) than those who failed weaning. This is in accordance with the findings of Kurachek et al. [11].

In addition, Fontela et al. [15] found that extubation failure was associated with younger age in their study on 124 children who were mechanically ventilated for longer than 12 h.

In addition, in the study by Baisch et al. [16] extubation failure patients were younger (median age of 6.5 vs. 21.3 months) in the studied group of 130 children.

With respect to the relation between weaning success and the underlying clinical diagnosis, the present study did not find a significant relation between weaning success and the underlying clinical diagnosis, which was in agreement with the study by Chavez et al. [17] who assessed the value of an SBT in predicting extubation success in 70 ICU children. However, this contradicts the results of Kurachek et al. [10] who concluded that chronic respiratory disorders and chronic neurological conditions are predictors of weaning failure. This may be explained by the different spectrum of clinical diagnoses involved in their study.

Considering the link between weaning success and duration of mechanical ventilation the present study has revealed that patients with successful weaning spent statistically shorter time on mechanical ventilation compared with those who failed weaning. This in harmony with the results of Edmunds et al. [18] who found that a higher incidence of extubation failure was associated with longer duration of ventilation. However, we did not find any significant association between hematological parameters, serum electrolytes, and weaning success.

The present study also investigated the relationship between respiratory parameters and weaning success. It was found that patients with failed to be weaned had statistically higher PaCO 2 . This is in agreement with the study by Thiagarajan et al. [19] who found that successfully extubated patients had lower PaCO 2 . Moreover, Bilan et al. [14] noted that hypercapnia (PaCO 2 > 50 mmHg) was seen to be the most common cause of extubation failure.

In addition, FiO 2 was significantly higher in patients with extubation failure. This is in accordance with the study by Khan et al. [20] who reported FiO 2 increase as a predictor of extubation failure. This study found that patients with successful weaning had significantly lower bicarbonate levels compared with those who failed weaning. This is in accordance with Wu et al. [21] who concluded that serum bicarbonate level less than 30 mmol/l is an independent predictor of extubation success.


  Conclusion Top


We conclude that patients who were successfully weaned were statistically older, spent less time on mechanical ventilation, had lower PaCO 2 and FiO 2 , and lower bicarbonate level compared with those who failed weaning. We did not find a significant relation between clinical diagnosis, hematological parameters, serum electrolytes, and weaning success.


  Acknowledgements Top


Conflicts of interest

None declared.

 
  References Top

1.Khemani RG, Markovitz BP, Curley MAQ. Epidemiologic factors of mechanically ventilated PICU patients in United States. Pediatr Crit Care Med 1991; 8:A39.  Back to cited text no. 1
    
2.Fagan JY, Chastre J, Domaet Y. Nosocomial pneumonia in patients receiving continuous mechanical ventilation. Am Rev Respir Dis 1989; 139:877-884.  Back to cited text no. 2
    
3.Pinsky MR. Breathing as exercise: the cardiovascular response to weaning from mechanical ventilation. Intensive Care Med 2000; 26:1164-1166.  Back to cited text no. 3
    
4.Esteban A, Frutos F, Tobin NU. Comparison of four methods of weaning patients from mechanical ventilation. N Eng J Med 1995; 16:573-577.  Back to cited text no. 4
    
5.Vallverdu I, Calaf N, Subirana M, Net A, Benito S, Mancebo J. Clinical characteristics, respiratory functional parameter and outcome of atom-hour T-piece trial in patients weaning from mechanical ventilation. Am J Respir Crit Care Med 1998; 158:1855-1862.  Back to cited text no. 5
    
6.Jubran A, Tobin MJ. Pathophysiologic basis of acute respiratory distress in patients who fail a trial of weaning from mechanical ventilation. Am J Respir Crit Care Med 1997; 155:906-916.  Back to cited text no. 6
    
7.Esteban A, Frutos-Vivar F, Ferguson ND, Arabi Y, Apezteguνa C, Gonzαlez M, et al. Noninvasive positive-pressure ventilation for respiratory failure after extubation. N Engl J Med 2004; 350:2452-2460.  Back to cited text no. 7
    
8.Wratney AT, Cheifetz IM. Extubation criteria in infant and children. Respir Care Clin N Am 2006; 12:469-481.  Back to cited text no. 8
    
9. 9 Schindler MB. Prediction of ventilation weaning outcome: children are not little adults. Crit Care Med 2005; 8:A39.  Back to cited text no. 9
    
10.10 Kurachek SC, Newth CJ, Quasney MW, Rice T, Sachdeva RC, Patel NR, et al. Extubation failure in pediatric intensive care: A multiple- center study of risk factors and outcomes. Crit Care Med 2003; 31:2657-2664.  Back to cited text no. 10
    
11.11 Randolph AG, Forbes PW, Gedeit RG, Arnold JH, Wetzel RC, Luckett PM, et al. Effect on mechanical ventilator weaning protocols on respiratory outcomes in infants and children; a randomized controlled trial. JAMA 2002; 288:2561-2568.  Back to cited text no. 11
    
12.12 Johnston C, de Carvalho WB, Piva J, Garcia PC, Fonseca MC. Risk factors for extubation failure in infants with severe acute bronchiolitis. Respir Care 2010; 55:328-333.  Back to cited text no. 12
    
13.13 Boles JM, Bion J, Connors A, et al. Weaning from mechanical ventilation. Euro Respir J 2007; 29:1033-1056.  Back to cited text no. 13
    
14.14 Bilan N, Shava SH, Ghaffari SH. Survey of factors effective on outcome of weaning from mechanical ventilation. Pak J Biol Sci 2009; 12:83-86.  Back to cited text no. 14
    
15.15 Fontela PS, Piva JP, Garcia PC, Bered PL, Zilles K, et al. Risk factors for extubation failure in mechanically ventilated pediatric patients. Pediatr Crit Care Med 2005; 6:166-170.  Back to cited text no. 15
    
16.16 Baisch SD, Wheeler WB, Kurachek SC, Cornfield DN, et al. Extubation failure in pediatric intensive care incidence and outcomes. Pediatr Crit Care Med 2005; 6:312-318.  Back to cited text no. 16
    
17.17 Chavez A, dela Cruz R, Zaritsky A. Spontaneous breathing trial predicts successful extubation in infants and children. Pediatr Crit Care Med 2006; 7:324-328.  Back to cited text no. 17
    
18.18 Edmunds S, Weiss I, Harrison R. Extubation failure in large pediatric ICU population. Chest 2001; 119:897-900.  Back to cited text no. 18
    
19.19 Thiagarajan RR, Bratton SL, Martin LD, Brogan TV, Taylor D. Predictors of successful extubation in children. Am J Respir Crit Care Med 1999; 160:1562-1566.  Back to cited text no. 19
    
20.20 Khan N, Brown A, Venkataraman ST. Predictors of extubation success and failure in. mechanically ventilated infants and children. Crit Care Med 1996; 24:1568-1579.  Back to cited text no. 20
    
21.21 Wu JY, Kuo PH, Fan PC, Wu HD, Shih FY, Yang PC. The role of non-invasive ventilation and factors predicting extubation outcome in myasthenic crisis. Neurocrit Care 2009; 10:35.  Back to cited text no. 21
    



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  Introduction
  Objective
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