Basics of Paediatric Mechanical Ventilation 

Let me try to answer your question in simple way. In spontaneous breathing, your breathing control centres regulate your RR based on your oxygen and CO2 levels. Its mostly the CO2 that drives your RR. When you intubate an adolescent for ARDS, the primary pathology is low oxygenation due to fluid in alveoli as well as lung interstitium. Since in mechanical ventilation, we take our body’s physiology, we cannot go very aggressively. So you will never start with very high RR, as RR will primarily deal with your CO2 levels and we do go for a bit permissive hypercapnia in our latest protocols. The main modus operandi in ARDS is high PEEP and low tidal volumes (4-6ml/ kg of ideal body weight). You would start with a high FiO2 and simply dial it down till it is maintaining sats of around 95% on natural RR of say between 10-14 breaths per min. You will still keep the I:E ration of 1:2. If increasing CO2 is an issue you can increase RR, as personally i wont risk increasing tidal volumes, but then with increasing RR to blow off CO2, i will increase I:E ratio to 1:3 to allow sufficient time for exhalation to prevent breath stacking and auto PEEP. I hope that clarifies. If you still need clarification, tell me and I will explain in more detail

@@nrkazmi hi.Thx u for the answer..it explains many things.. but I apologize I need to ask you again..If I set the RR to, for example, 15 but the spontaneous RR is 40 , how should I set the Ti and I :E ratio? I mean, if I set the Ti based on RR 15, the set Ti should be around 1.33 (but that Ti will make the monitored I:E ratio to be around 7.8 :1 because the spontaneous RR is 40). So, what should I do to prevent this asynchrony and breath stacking? Thank u

@@latestlatest4760 here in your question, it is not clear that when you say spontaneous RR, do you mean spontaneous RR while being awake without being intubated or do you mean spontaneous RR on mechanical ventilator. Both are different things. When you put a patient on ventilator, depending on the condition, it depends which mode are you going for. The modes that allow for spontaneous breathing are Synchronised mandatory intermittent ventilation which can then be with pressure control or pressure support. If you mean spontaneous RR while not being intubated then it becomes irrelvant when you intubate because then you will go according to body physiological parameters being dictated by your ABGs and clinical features, but if you are referring to spontaneous breaths while being on SIMV, then the spontaneous breaths are supported by pressures, and you dont change any parameters for sponatenous breaths except the amount of pressure which can be set to help push in the breath. Here in such a case your tidal volume, I:E is set for the mandatory breaths that you have set. Lets say your mandatory breaths are 15, then mandatory breaths will be delivered only if the spontaneous RR falls below 15 and then a mandatory breath wil be given according to your set parameters. But if is continously spontaneously breathing at RR of 40, you need to double check, as some pathological process is still going on causing a high RR. SIMV is usually used close to weaning off, when most of the pathological process is cleared up or clearing up. Personally for me a child who is having such a high spontaneous RR on SIMV, i would have to check by setial xrays, or if needed by CT or bronchoscopy to see whats going wrong where. To overcome asynchrony, you wont go for SIMV at an early stage. Such a case would need deep sedation and muscle relaxation and ventilated with CMV till pathological process is cleared up and then you can trial SIMV but spontaneous RR needs to be close to physiological one

@@nrkazmi hi..thx u for another great reply..thanks..sorry for not being clear in my posts. What I meant was if the patient has a high respiratory drive (for example, a severely metabolic acidotic patient with ARDS) and so he is driving the rate on the AC-PC mode very fast (in other words, the Total Resp. rate is high) So, what I was asking actually was whether to set the resp rate on the ventilator near the total Resp rate (so that the patient has an acceptable I:E ratio) or to give a deep sedation/analgetic to such patient while correcting the metab acidosis and ARDS so that the patient can follow our set parameters? Thank you

@@latestlatest4760 i would go for deep sedation and control everything till physiological parameters are more acceptable and then can go to more relaxed modes of ventilation

@Ahsan Beg. Thanks for your comments. I will make a lecture on monitoring ventilators shortly specially how to read scalars and waveforms. In the meanwhile you can watch my other videos on applied aspects of ventilation by visiting these links ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-plQAhNJuQas.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2-IXNLGRauA.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-AcJXCVBitA8.html

I will soon be uploading two more lectures in continuation if this one. For the time being, I have a short video on some quick tips here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-AcJXCVBitA8.html

@@nrkazmi dr when u will upload next lecture please it’s really help full thank you

@@afnan6336 please watch my detailed lecture here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2-IXNLGRauA.html