Description

Welcome to PICU Doc On Call, A Podcast Dedicated to Current and Aspiring Intensivists.

I'm Pradip Kamat

and I'm Rahul Damania and we are coming to you from Children's Healthcare of Atlanta - Emory University School of Medicine.

Welcome to our PICU Mini-Series Episode a 10 month old who is intubated for acute respiratory failure secondary to RSV bronchiolitis.

Here's the case:

A 10-month-old full-term infant girl old is intubated for acute respiratory failure secondary to RSV bronchiolitis. Patient was brought to the ED by parents on day 3 of her illness with h/o cough, congestion and worsening respiratory distress. She has had increasing WOB and grunting. After assessment in the ED where the patient had a brief trial of HFNC, she was intubated with a 4.0 ETT due to persistent hypoxemia. Pertinently, her viral panel was positive for RSV, and the patient was transferred to the PICU. In the PICU, patient was ventilated using PRVC: Set TV of 90cc (patient is 11KG), PEEP 6, PS 10, and FIO2 40%. Throughout her course, she was mechanically ventilated and sedated for about a week. She required a continuous infusion of rocuronium due to decreased lung compliance and high peak pressures. Patient weaned on her ventilator settings by ICU day 7 and the decision to move towards extubation was made.

To summarize key elements from this case, this patient has:

• 10 month old with acute respiratory failure secondary to RSV infection and with a secondary bacterial infection due to H.Influenza.
• Had about a six day course on the ventilator requiring sedation and NMB
• and now we are at the discussion of extubation readiness.Rahul, do you mind summarizing the patient's peri-extubation course?

Sure Pradip, so on day 6 of hospitalization our patient was weaned to low mechanical ventilator settings. The chest radiograph, which initially showed evidence of interstitial pneumonitis and atelectasis now improved and the patient had improved secretion burden. The patient was on ceftriaxone throughout the hospital course as her ETT cx with which grew Hemophilus Influenzae.

• What about the patient's neurological status?
• The patient was initially on fentanyl, dexmedetomidine and a rocuronium infusion — a day prior to considering extubation, the patient was off of the continuous rocuronium infusion oxygenating and ventilating well. The patient prior to extubation was wide awake and appropriate during the morning sedation holiday.
• Any other important clinical markers?
• Yes, the patient's clinical exam including lung exam was reassuring. The patient underwent a pressure support trial PEEP 5, CPAP 10 and had a normal respiratory effort with exhaled of about 5 mL/kg. The RT, however mentioned that the patient did not have a "leak" when performing the leak test. The finally the patient was given a few doses of furosemide for diuresis prior to extubation.
• Awesome, today's episode we really want to focus on extubation readiness however prior to this discussion, can we take a step back and talk about some red-flag symptoms which led to intubation for this patient?
• This patient had severe respiratory distress which progressed to failure.
• The tachypnea, decreased mentation, and grunting were key signs that the patient was progressing to endotracheal intubation.
• Grunting is important to highlight as this refers to the child generating auto-PEEP to combat the atelectasis present in bronchiolitis.
• Remember that a child's chest wall has a high compliance and a decreased propensity for outward elastic recoil — this in essence reduces FRC and thus there is a more balance towards the inward recoil of the long (closing capacity). The highly compliant chest wall and the natural inward recoil of the infant lung creates a propensity towards atelectasis and subsequent impairments in breathing. Low FRC can also create increase PVR which can thus imbalance optimal cardiopulmonary interactions.

OK let's transition to our topic of discussion by a quick summary:

• A 10 month old after 6 days of MV is now ready for extubation.
• Let's start with a short multiple choice question:
• In children deemed ready for extubation by clinicians, which of the following is most likely to be associated with reintubation?
• A) High breath by breath variability
• B) Failed Pressure Support trial
• C) Duration of mechanical ventilation
• D) No leak around the ETT prior to extubation
• Correct answer is A. Pediatric extubation failure rate ranges from 2-20%. Although extubation failure is usually multifactorial, High respiratory variability during spontaneous breathing trials is independently associated with extubation failure in children.
• A recent paper by Kelby et al in CCM 2020-found that after controlling for confounding variables such as age and neurologic diagnosis, reported that both coefficient of variation of respiratory rate and decreased maximal change in airway pressure generated during airway occlusion had almost 3-fold higher risk of extubation failure. When this subset of children developed post-extubation upper airway obstruction, reintubation rates were greater than 30%.
• What about the other factors we had in our answer choices like the Pressure Support Trial?
• Children fail PS trial for variety of reasons including ETT size, sedation, to name a few. Khemani and colleagues (Intensive Care Med. 2016 Aug; 42(8):1214-22)reported that regardless of endotracheal tube size, pressure support during extubation readiness tests significantly underestimates post-extubation effort of breathing.
• Further, A 2009 paper by Newth et al (Pediatr Crit Care Med. 2009 Jan;10(1):1-11.) reported in systematic review of weaning and extubation for pediatric patients on mechanical ventilation, that extubation failure bore little relationship to the duration of MV.
• I think it is important to highlight that though we frequently perform PS trials, we should assess other factors such as primary reason for extubation being reversed, secretions, and even neuromuscular components - extubation does not just refer to lungs being ready to have less support!
• Yes Rahul, absolutely agree — I do want to mention A controversial topic has always been the utility of measuring a leak pressure around the ETT to predict upper airway obstruction. A study by Khemani et al (Am J Respir Crit care 2016 Jan 15;193(2):198-209) reported the risk factors independently associated with subglottic UAO, included low cuff leak volume or high preextubation leak pressure, poor sedation, and preexisting UAO (P < 0.04) for cuffed ETTs; and age (range, 1 mo to 5 yr) for uncuffed ETTs (P < 0.04). For uncuffed ETTs, the presence or absence of preextubation leak was not associated with subglottic UAO.
• Lets summarize - upper airway obstruction involves checking if there is flow (in the form of pressure) surrounding the ETT — key point younger patients (1 mo to 5 yr old) with uncuffed tubes have risk to develop UAO peri-extubation.
• An older study by Wratney et al (Pediatr Crit Care Med. 2008 Sep;9(5):490-6) had previously reported that an endotracheal tube air leak pressure >/=30 cm H2O measured in the non-nparalyzed patient before extubation or for the duration of mechanical ventilation was common and did not predict an increased risk for extubation failure. The authors in that study concluded that- Pediatric patients who are clinically identified as candidates for an extubation trial but do not have an endotracheal tube air leak may successfully tolerate removal of the endotracheal tube.
• This suggests that having a leak may not be necessary for a patient to successfully extubate.
• So Rahul for our listeners What are factors associated with extubation failure?
• Thats an excellent question. Factors correlated with an increased risk of extubation failure include a longer duration of sedative use, younger age, higher complexity of medical conditions, and diaphragmatic dysfunction. The most common reported cause of extubation failure in pediatric patients is upper-airway obstruction, with other causes that include respiratory insufficiency, muscular weakness, cardiac dysfunction, and neurologic impairment. Duration of MV, PRISM III score did not predict extubation in a multivariable analysis reported by Krasinkiewicz et al (Respiratory Care April 2021 Vol 66 No 4).

Pradip, What are the main barriers to extubation in pediatrics?

Thats an excellent question Rahul. One study published in Respiratory Care in` 2021 Vol 66 No 4) reported that in patients who had their passed the extubation readiness test, most common reason for holding off extubation was a planned procedure, neurologic diagnosis/status of the patient, and no leak around the ETT, other factors included high ventilator rates and over sedation, hemodynamic instability, fluid status etc.

I think it is important for us to truly consider procedures or imaging which are planned to play a factor in our timeline for extubation readiness - this mitigates the risk for re-intubation - which is especially important in children with difficult airways!

Rahul: how do majority of children's hospitals perform extubation readiness test prior to extubation?

• I think Pradip there is considerable variation in the methodology of ERT. Some common practices which I have noted as a fellow include: A daily spontaneous breathing trial performed probably early in the am (~4am) by the RTs. As long as patient didn't require any procedure (imaging or surgery), hemodynamically stable, patient spontaneously breathing, FIO2 < 50% (some use 40%),...