Automation of Weaning in Children

as a surrogate for blood gas PCO2, to decrease or increase ventilatory support. IntelliVent® also uses SpO2 to decrease or increase PEEP and FiO2. The two ECPs were studied in children during the weaning phase and the first clinical studies are promising. However, further clinical trials are needed to better assess the efficacy and tolerance of these two ECPs in children and to develop ECP that are dedicated to all ages including neonates.

61.1 Introduction

Discontinuing mechanical ventilation as soon as it is no longer needed is crucial in preventing respiratory and prolonged sedation complications. The weaning process is described in a previous chapter (see section on weaning Part XXII) and can be summarised in six steps according to the sixth international consensus conference on intensive care medicine (Boles et al. 2007) including (1) suspicion that weaning may be possible, (2) assessment of readiness to wean, (3) spontaneous breathing trial (SBT) performed, (4) SBT passed, (5) extubation and (6) assessment of successful or failure of extubation (Fig. 61.1). Between each steps mechanical ventilation has to be adapted to reach the next step until no ventilator support is needed anymore. At present, two explicit computerised protocols on weaning children from mechanical ventilation are implemented in commercialised ventilators. This chapter describes these two explicit computerised protocols: Smartcare/PS® by Draeger Medical (Germany) and IntelliVent® by Hamilton Medical (Switzerland).
A187909_1_En_61_Fig1_HTML.jpg
Fig. 61.1
Schematic representation of the different steps during weaning from mechanical ventilation in children

61.2 SmartCare/PS®: Draeger Medical

SmartCare/PS®—PS stands for pressure support—is an autopiloting, knowledge-based software application that provides an ECP for the automated control of pressure support ventilation. This ECP manages, without the need of caregivers intervention but under their supervision, the four following therapeutic procedures: (1) automatic adaptation of the pressure support level to keep the patient inside a “zone of respiratory comfort”, i.e. normal ventilation (see below); (2) a strategy to gradually and progressively decrease the level of pressure support level; (3) an automated SBT when the patient reaches a minimum ventilatory support; and (4) a recommendation of separation from the ventilator when the SBT is successfully passed (Table 61.1).
Table 61.1
Characteristics of the SmartCare/PS® Draeger Medical and IntelliVent® Hamilton Medical explicit computerised protocols
Characteristics
SmartCare/PS®
IntelliVent®
Mode of ventilation
PS
ASV
Body weight range for use (kg)
≥15
≥7
Weaning steps managed (see Fig. 61.1)
2–4
1–4
Primary goal of the ECP
Wean patient while maintained innormal ventilation (see Table 61.2)
To maintain in a normal $$ {\mathrm{ET}}_{{\mathrm{PCO}}_2} $$ , RR and SpO2 ranges
Initial settings
IBW, humidification system, medical history
IBW, medical history
Setting modification displayed but needcaregiver prescription (open loop)
No
Yes
Input data
2min V t, 2minRR, $$ {}_{2 \min }{\mathrm{ET}}_{{\mathrm{PCO}}_2} $$ , PEEP, PS level, ventilator messages
RR, $$ {\mathrm{ET}}_{{\mathrm{PCO}}_2} $$ , SpO2
Rules displayed to caregivers when applied
No
±
Output data
Parameter display, e.g. PS level
MV, PEEP, FiO2
Therapeutic messages “SBTsuccessful”
SBT duration
SBT
Yes
Yes
SBT duration
1–2 h according to initial PS level(Jouvet et al. 2007)
Adjustable
Recommendation of separation from the ventilator
Yes
No
PS pressure support, ASV adaptive support ventilation, IBW ideal body weight for height, V t tidal volume, RR respiratory rate, $$ {\mathrm{ET}}_{{\mathrm{PCO}}_2} $$ end-tidal PCO2, SpO 2 pulse oxygen saturation, 2min V t , 2min RR or $$ {}_{2 min}\mathrm{E}{\mathrm{T}}_{{\mathrm{PCO}}_2} $$ mean value on 2 min of V t, RR or $$ {\mathrm{ET}}_{{\mathrm{PCO}}_2} $$ , MV minute volume, PEEP positive end-expiratory pressure, FiO 2 inspired fraction of oxygen, PIP positive inspiratory pressure, SBT spontaneous breathing trial
SmartCare/PS® is available on Draeger’s Evita XL and the latest generation of Draeger Medical ventilators: Evita Infinity V500. It is applicable in two applications that slightly differ: (a) for patients with ideal body weight (IBW) between 15 kg and 35 kg as well as for (b) patients with IBW between 36 kg and 200 kg. The ECP comprises of the three different phases “adaptation”, “observation” and “maintain” to perform ventilation procedures (1) to (4). It will also manage patient instabilities, e.g. transient tachypnoea, and it can cope with certain patient care situations like suctioning and pauses during specialised therapeutic situations like nebulisations or during specific ventilator alarm.

61.2.1 Basics of SmartCare/PS®

61.2.1.1 Initiation of SmartCare/PS®

Initiating SmartCare/PS® is recommended when a child, with IBW greater than 15 kg, fulfils ready-to-wean criteria that were used in two prospective clinical studies (Jouvet et al. 2007; Jouvet et al. 2010a). These weaning criteria are as follows:
  • The attending physician evaluates that the patient is able to breathe spontaneously or the patient is already breathing spontaneously.
  • No significant vasopressors or inotropic medications, excluding digoxin or low-dose dopamine (≤5 μg/kg/min).
  • Slight or no endotracheal tube gas leakage ([V ti−V te]/V ti ≤20 %).
  • Mechanical ventilation with a plateau pressure above PEEP ≤25 cmH2O.
  • PEEP ≤8 cmH2O.
  • FiO2 ≤60 % with SpO2 ≥95 %.
  • Pressure support test passed. During the pressure support test, the patient is mechanically ventilated in pressure support mode for 30 min, with a level of pressure support set to ±5 cmH2O of the current plateau pressure. The pressure support test is stopped before 30 min if the patient shows evidence of respiratory distress (respiratory rate below 10 breaths per min or above 40 breaths per minute and FiO2 >60 % in order to obtain a SpO2 ≥95 %). The test is passed when, after 30 min, the patient remains stable with a respiratory rate between 10 and 40 breaths per min, an expiratory tidal volume higher than 6 ml/kg and SpO2 ≥95 % with FiO2 ≤0.6.
When the child fulfils all the above mentioned criteria, IBW, which is also a surrogate for lung volume (see chapter on explicit computerised protocols), is prescribed on the ventilator by the user. The next step is to prescribe the humidification system and the medical history (presence or not of neurologic disorders or COPD) if the child’s IBW is above 35 kg. These user-given settings will determine certain thresholds and specific rules of the ECP (Table 61.2).
Table 61.2
Normal ventilation definition in SmartCare/PS®
Definition
Parameters value
IBW ≤35 kg
35 kg <IBW ≤55 kg
IBW >55 kg
Normal ventilation:
RR low (bpm)
18
10–15
10–15
RR low ≤ RR < RR high
RR high (bpm)
40
20–40
20–40
34 for COPD & neurological disorders
34 for COPD & neurological disorders
V T low ≤ V T
V t low
6 ml/kg
250 ml
300 ml
$$ {\mathrm{ET}}_{{\mathrm{PCO}}_2} $$  <  $$ {\mathrm{ET}}_{{\mathrm{PCO}}_2} $$ high
$$ {\mathrm{ET}}_{{\mathrm{PCO}}_2} $$ (mmHg)
55
45–65
45–65
65 for COPD
65 for COPD
RR max (bpm)
50
36
36
IBW ideal body weight, COPD chronic obstructive pulmonary disease

61.2.1.2 Primary Goal: To Safely Maintain the Child in a Zone of Respiratory Comfort (Normal Ventilation)

In contrast to conventional ventilation modes, SmartCare/PS® continuously adapts the pressure support level to maintain normal ventilation. Normal ventilation corresponds to a respiratory pattern that is determined by lower and upper thresholds of tidal volume, respiratory rate and $$ {\mathrm{ET}}_{{\mathrm{PCO}}_2} $$ (Table 61.2). In turn, these thresholds are defined within acceptable limits as reported by a large panel of paediatric intensivists (Santschi et al. 2007). To keep the patient in normal ventilation, the pressure support level is increased or decreased according to the implemented rules of the knowledge base that represents the ECP (Fig. 61.2) (Mersmann 2009).
A187909_1_En_61_Fig2_HTML.jpg
Fig. 61.2
Classification of ventilation by SmartCare/PS® Draeger Medical. Pressure support level is modified according to values of tidal values (below Vtlow: panel a, above Vtlow: panel b), respiratory rate and end-tidal PCO2 at 2–5 min intervals (SmartCare waits 2 min for the next “Classification of Ventilation” if PS was not changed and waits 5 min if PS was changed (either by SmartCare or by the user))

61.2.1.3 Weaning of Ventilatory Support

When the child remains in normal ventilation for a predefined period of time (60, 30 and finally 15 min), the PS level is gradually decreased (Jouvet et al. 2007), which is called a regular weaning step. During the entire execution of the ECP, duration of stability and duration of instabilities are balanced and taken into account when assessing the patient’s needs. When the patient’s respiratory pattern is outside the limits of normal ventilation, an instability is noted. A maximum of two instabilities will be tolerated by SmartCare/PS® before the pressure level will be increased.

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  3. Airway Humidification
  4. Automation of ALI/ARDS Ventilation in Children

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Sep 26, 2016 | Posted by in PEDIATRICS | Comments Off on Automation of Weaning in Children

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