The Role of POCUS in the Process of Weaning from Mechanical Ventilation in children:�Evidence – based and Clinical Application�

Ngô Tiến Đông

PICU, Vietnam National Children's Hospital 

Why?

• No standardised protocols exist to guide weaning from MV
• The failure rate of children weaning: 8–20%
• POCUS
• Safe, effective
• A promising tool to predict successful weaning and extubation: lung ultrasound, airway ultrasound, hemodynamic assessment

2

Weaning from ventilation and extubation

3

• No standardised protocols exist
• A systematic approach: Extubation readiness testing (ERT) and spontaneous breathing trials (SBT)
• Mainly a clinical judgment subjective decision

Egbuta. BJA Education (2022)

​

Predictive indexes for successful weaning from MV

4

Egbuta. BJA Education (2022)

​

The ‘air leak’ test�to predict which patients are at risk for postextubation stridor and extubation failure �

• Increased risk for post-extubation stridor or extubation failure when there is absence of a leak around the ETT or leak at a > 30 cm H2O

Kemper KJ et al. Crit Care Med 1991

• A leak around the ETT at > 20 cm H2O had a sensitivity of 83.3% in predicting post-extubation stridor in patients age > 6 years

Mhanna MJ et al. Crit Care Med 2002

​

• 3 x higher incidence of adverse events in patients without an air leak at 25cmH2O

Suominen Pet al. Paediatr Anaesth 2006;

Ultrasonography becomes useful

• Predicting weaning success: None of optimal indexes.
• 20% of successful SBT patient still require a subsequent re-intubation
• POCUS
• Predict
• Deeper understanding of the root causes behind weaning failure

6

Hemodynamic Assessment through Echo

7

Transmural pressure

Cardiopulmonary interactions

• Increases LV afterload
• Increases transmural pressure
• Increase in the work of breathing 🡪 increased serum catecholamine levels

🡪 Cardiac dysfuntion

Jozwiak. Annals of Intensive Care (2024)

Cardiac dysfunction induced by weaning from MV�

• Weaning-induced pulmonary oedema (WIPO)
• The risk factors: COPD, cardiopathy, obesity, positive fluid balance...
• Left ventricular diastolic and systolic dysfunction: involved in the pathophysiology of WIPO
• Echo: a non-invasive, real-time, useful

8

Egbuta. BJA Education (2022)

​

Parasternal Long Axis View with M mode�

Left ventricular contractility

Fraction shortening (FS)

�

LV FS = (LVIDd - LVIDs) / LVIDd x 100%�LVIDd - left ventricular internal diameter diastolic�LVIDs - left ventricular internal diameter systolic

Left ventricular contractility

Diastolic dysfunction

11

Hemodynamic Assessment through Echo

• Patients with an EF < 35% and an E/e’ ratio > 7.8 were more likely weaning failure

Caille. Crit. Care 2010

• E/e’ cut-off 14.5 weaning failure: specificity of 95.8% and a sensitivity of 75%. Systolic dysfunction had no association with weaning outcomes

Moschietto. Crit. Care 2012

• Failure of weaning was associated worse left diastolic function (E wave, e’ wave, E/e’) and a high E/e’ ratio. No association between left ventricular systolic dysfunction

Sanfilippo. Br. J. Anaesth. 2021

​

12

Lung ultrasound

13

Bedside Lung Ultrasound in Emergency (BLUE) protocol. The total LUS score: 0-36

0

1

2

3

15

16

The best cut-off value of LUS for predicting weaning failure was ≥12 with an AUC of 0.934, sensitivity of 85.7% and a specificity of 81.2% (p < 0.001).

Abdel Rahman. Indian J Pediatr. 2020

Ultrasonographic Assessment of Respiratory Physiotherapy

• No Volume lost, dynamic air bronchogram🡪more likely Pneumonia

specificity of 94% and a positive predictive value of 97% for pneumonia

​

• Volume lost , static air bronchogram --> more likely atelectasis

the absence of dynamic air bronchograms does NOT rule out pneumonia

​

17

Ultrasonographic Assessment of Respiratory Physiotherapy

• Atelectasis 🡪 Physiotherapists 🡪 �LUS to assess the efficacy �of treatment.

​

​

18

Ultrasonographic Assessment of Diaphragmatic Function

• The diaphragm has a significant role in breathing (75% at rest)
• MV can cause diaphragmatic atrophy and dysfunction.
• Diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF): useful in weaning from MV

​

​

19

Gao Y. Front. Pediatr. 2023

Diaphragmatic excursion (DE) measurements

20

21

0-2 years old

2-6 years old

6-12 years old

Chong CY. Med JMalaysia. 2022

22

0-2 years old

2-6 years old

6-12 years old

Chong CY. Med JMalaysia. 2022

23

The optimal threshold of DE

• Abdel Rahman, 1 m to 170 m, n= 106, The best cut-off value of DE ≥6.2 mm , AUC of 0.876, a sensitivity of 87.5% and a specificity of 66.7%

Abdel Rahman . Indian J Pediatr. 2020

• Yao, 1–3 y old, n= 72, the optimal threshold DE ≥ 8.08 mm, the AUC of DE 0.72, the sensitivity 0.55, and the specificity 0.81

Yao. Front. Pediatr.2022

24

Diaphragm Paresis in children

25

• DE ≤4 mm and difference of DE between hemidiaphragms >50%

🡪 decreased or paretic

Diaphragmatic thickening fraction

26

Diaphragmatic thickening fraction

27

Diaphragmatic thickening fraction

28

29

Anita Duyndam, PREPRINT.2023

Age of O-1 y thicker than older

Atrophy diaphragm in MV

• Christie L, 56 patients (median age 17 m, use of neuromuscular blockade infusion (NMB) one third of the patients; DTF at the initial 9.7%; 24 h prior to extubation14.8%.
• NMB 🡪 low dTF, increased the daily atrophy rate
• There was no significant difference in the daily rate of atrophy among subjects exposed to corticosteroids

30

Glau CL, Pediatr Crit Care Med. 2018

Montoro DV, Pediatric Respiratory Reviews. 2021

Cut off of DTF for predicting weaning

• Xue et al, 50 ventilated children between 0 and 18 years old, with a mean age of 3 years

​

​

Abdel Rahman, 160 Ventilated, 1 mo to 170 mo

​

�

Abdel Rahman. Indian J Pediatr.2020

31

Xue Y, BMC Pulm Med. 2019

Cut off of DTF for predicting weaning

Duyndam, 53 patients, with median age 3.0 months

​

​

32

Ultrasound to Predict Post-extubation Stridor

• Post-extubation stridor (PES) :2–15% in critical children 🡪 reintubation
• A few predicted clinical characteristics: the length of the intubation, the number of times it was attempted, and infection
• One of the standard methods for predicting LE is cuff leak test

🡪 However, literature is variable with differing results

33

Bharti B. Inter J Pediatric Otorhinolaryngol. 2016

Jang M. International J Pediatric Otorhinolaryngol. 2018

Jaber S. Intensive Care Med. 2003

(A) Cricothyroid membrane level

Landmark: the Vocal cord, false cords, thyroid cartilage and arytenoids cartilage

​

Assessment of ACWD

35

ACWD = postdeflation air column width − predeflation air column width

36

50 ventilated, median age 4.5 mo, endoscopy for stridor pts after extubated (18%)

How to integrate ultrasound (US) into the process of weaning from mechanical ventilation.

37

38

Conclusion

POCUS can be used in bedside weaning assessments

• Assess diastolic function, left ventricular ejection fraction at high risk of weaning failure
• The LUS in clinical protocols: cut- off value 12
• Cut-off values for successful weaning: DTF > 20-25%, DE > 10 mm.
• Laryngeal air column width ratio (ACWD): reliable method for the prediction of PES

​

39

The Role of POCus in the Process of Weaning from Mechanical Ventilation in children:�Evidence – based and Clinical Application�

Chân thành cám ơn!

​