|Year : 2021 | Volume
| Issue : 3 | Page : 117-118
The real test of spontaneous breathing trials: Getting children to spontaneously breathe earlier!
Garrett Keim1, Vijay Srinivasan2
1 Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA
2 Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia; Department of Anesthesiology, Critical Care and Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
|Date of Submission||31-Mar-2021|
|Date of Acceptance||06-Apr-2021|
|Date of Web Publication||21-May-2021|
Dr. Vijay Srinivasan
Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Keim G, Srinivasan V. The real test of spontaneous breathing trials: Getting children to spontaneously breathe earlier!. J Pediatr Crit Care 2021;8:117-8
|How to cite this URL:|
Keim G, Srinivasan V. The real test of spontaneous breathing trials: Getting children to spontaneously breathe earlier!. J Pediatr Crit Care [serial online] 2021 [cited 2023 Jun 2];8:117-8. Available from: http://www.jpcc.org.in/text.asp?2021/8/3/117/316598
The consummate question that practitioners face when liberating an intubated child from invasive mechanical ventilation is: When is the right time to trial extubation? A multitude of factors, both subjective and objective, contribute to this challenging decision. The mental status of the patient is a key determinant of successful extubation, and mental status may often fluctuate, especially in the presence of sedative medications that are being titrated. Even in the case of quantifiable factors such as the presence of a leak around the endotracheal tube, endotracheal tube suctioning requirements, and inspired concentrations of oxygen delivered, consensus on what is appropriate is lacking and published evidence is scant. Despite the seeming complexity involved in deciding when to extubate, extubation failure in children is relatively uncommon with a reported rate of only 6.2% in a large multi-institutional study. The most common reason for extubation failure in this study was upper airway obstruction. Notably, extubation failure can occur even when a leak test demonstrates adequate endotracheal cuff leak. Nevertheless, improving extubation practices is an important area of investigation with the potential to enhance care around this critical event during recovery from critical illness in children.
Spontaneous breathing trials (SBT) are commonly employed by practitioners as a test of extubation readiness. SBTs aim to simulate the postextubation environment and serve to gauge respiratory effort that can be expected after extubation. Previously published survey data has shown that 95% of pediatric critical care practitioners utilize continuous positive airway pressure (CPAP) with pressure support (PS) as their preferred mode of SBT, with the use of CPAP alone being much less common. The addition of PS is often touted as a strategy to overcome the resistance from small diameter endotracheal tubes in children, but this practice may be rather fallacious and unnecessary. Resistance at the level of the endotracheal tube depends on airflow rate through the tube, and airflow rates in intubated children have been shown to be sufficiently low enough to avoid causing endotracheal tube resistance. In a previous study, Khemani et al. used pressure-rate products as a surrogate for breathing effort. This seminal work demonstrated that both CPAP/PS and CPAP via endotracheal tube before extubation resulted in lower pressure-rate products, or to put it more simply, these modalities required less effort from the child, compared to spontaneous breathing after extubation.
In this issue of the Journal of Pediatric Critical Care, Bairwa et al. reported the results of a single-center, unblinded, randomized control trial of SBT using CPAP alone versus T-piece with a primary outcome of extubation failure (defined as the need for reintubation within 48 h of extubation). The authors enrolled a total of 60 children and randomized 30 to each group. Demographically, the groups were similar without differences in age, biologic sex, indication for mechanical ventilation, or duration of ventilation between the two groups. There was no difference in the primary outcome of extubation failure with four reintubations occurring in each group. In this study, respiratory distress as determined by the authors was the cause of extubation failure in one child in the CPAP SBT group and two children in the T-piece SBT group. There were no statistically significant differences in secondary outcomes including the requirement for postextubation noninvasive positive pressure ventilation or high-flow nasal cannula therapy, duration of any oxygen therapy, and intensive care length of stay between the two SBT groups.
The key strength of this study is that it is one of the first pediatric studies to compare SBT utilizing CPAP alone versus T-piece. The randomized design successfully achieved the balance of key demographic factors. The authors also nicely characterized changes in vital signs and arterial blood gas parameters for both groups during SBT. However, measures of the severity of illness were not included in the study and may be an important potential confounder. In addition, the authors do not address the question of whether the lack of CPAP in the T-piece only SBT group may have led to the loss of end-expiratory lung volume, especially in younger children. The key limitation of this study is the small sample size and lack of adequate power to draw any meaningful conclusion about the primary outcome. Simulations of sample size requirements show that even if T-piece SBT optimistically reduced extubation failure by 40%, based on the rate of extubation failure seen in this study (13%), an excess of 1000 participants would need to be enrolled and randomized to have an adequately powered study. This is a herculean task even for a large multi-center trial and very unlikely to be feasible.
Perhaps, the question that we should really be asking is: Is there a point to performing SBT in children? Can we really improve significantly from an already low extubation failure rate of 6%? In theory, SBT is at best testing the work of breathing in a patient following extubation. With the addition of this report, multiple studies have now tested CPAP/PS, CPAP alone or T-piece for SBT without reporting immediate adverse events as long as patients are monitored and SBT failure criteria are clearly outlined. Data from adult surgical intensive care suggest that daily SBT with extubation after a successful SBT shortened duration of mechanical ventilation without necessarily altering extubation failure rates. Although earlier extubation has the potential to increase extubation failure rates, the question of which is the best approach to SBT then becomes a more realistic and pertinent question for us to investigate if practitioners use SBT to predict extubation readiness rather than extubation failure. We suggest that this is the direction that we should be moving toward when we discuss the future of assessing extubation readiness. Perhaps, the real test of SBT is to get children breathing spontaneously earlier…
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