Basic of mechanical ventilation

Basic of mechanical ventilation

1. Dr.Azad A Haleem AL.Mezori MRCPCH,DCH, FIBMS Assistant Professor University Of Duhok College of Medicine Pediatrics Department [email protected] Basics of Mechanical Ventilation

2. Introduction Spontaneous breathing is defined as movement of air into and out of the lungs as a result of work done by an individual’s respiratory muscles. Oxygen  is a drug and should be prescribed with a target saturation range. The air that we breathe contain approximately 21% oxygen.

3. Methods to administer Oxygen Non – Invasive : Invasive: Endotracheal intubation with mechanical ventilation

4. Device of oxygen therapy in PICU

5. DEFINITION OF MECHANICAL VENTILATOR A ventilator is a machine that delivers a flow of gas for a certain amount of time by increasing proximal airway pressure , a process which culminates in a delivered tidal volume through using various modes of ventilation.

6. Goals of Mechanical Ventilation Relieve respiratory distress Decrease work of breathing Improve pulmonary gas exchange Reverse respiratory muscle fatigue Permit lung healing Avoid complications

7. Indications for Mechanical Ventilation Airway Protection: General Anesthesia. Increased Work of Breathing: laryngeal edema, asthma, COPD,cardiogenic or non-cardiogenic pulmonary edema), pulmonary infection, pulmonary hemorrhage &fibrosis. Hypoxemia. Increased Demand: Severe acidosis, pulmonary embolism, severe circulatory shock Alveolar Hypoventilation: Won’t breathe” Apnea , drug-induced sedation, central nervous system disorders, or profound systemic disorders such as circulatory shock and metabolic encephalopathy. “Can’t breathe” Neuromuscular Weakness: Acute: Guillain-Barre syndrome, Chronic: myasthenia gravis, Myopathy.

8. What you need for Mechanical ventilation Prepare and check all equipments for intubation : Cuffed and not cuffed endotracheal tube (in neonates use uncuffed ones) Stylet Laryngoscope with blades Stethoscope Syringe Plaster

9. Size of tube internal diameter Weigth gram Gestational age (weeks) 2.5 Lower 1.000 Lower 28 3.0 1.000 - 2.000 28 - 34 3.5 2.000 - 3.000 34 - 38 3.5 – 4.0 Upper 3.000 Upper 38 SIZE & INSERTION DEPHT OF ENDOTRACHEAL TUBE Weigth Depth (cm) Lower 1.000g 6 cm 1.000 - 2.000g 7 cm 2.000 - 3.000g 8 cm 3.000 - 4.000g 9 cm Upper 4.000g 10cm

10. Patient : Physical examination, Respiratory rate (set, spontaneous), Rib cage-abdominal motion, Work of breathing. Monitoring vital signs and Sp02 ABG: Gas exchange. Mechanical Ventilation Machine: tidal volume, Peak inspiratory pressure, PEEP & waveform. Monitoring during Mechanical Ventilation

11. Screen of Mechanical ventilation

12. What you can control in Mechanical Ventilation Volume V : Tidal volume: how much air would you like to get in and out of patient. Pressure P : how much pressure would you like to give. Rate R.R : how fast would you like the patient to breath? Breath \ min Flow rate F.R : Flow = Volume \ Time. How fast would you like the patient to push the volume in. Oxygen O : how much oxygen would you like to put in. Who is going to control the work is breath? The machine or the patient. Trigger Combination of mentioned factors together will give you selected mode of ventilation.

13. Physiology Airway resistance  refers to the resistive forces encountered during the mechanical respiratory cycle. The normal airway resistance is ≤ 5 cmH2O. Lung compliance  refers to the elasticity of the lungs, or the ease with which they stretch and expand to accommodate a change in volume or pressure. Lungs with a low compliance, stiff” lungs, tend to have difficulty with the inhalation process. An example of poor compliance would be a patient with a restrictive lung disease, such as pulmonary fibrosis. In contrast, highly compliant lungs, or lungs with a low elastic recoil, tend to have more difficulty the exhalation process, as seen in obstructive lung diseases.

14. Pressure Peak Inspiratory Pressure (PIP or Ppeak )  is the maximum pressure in the airways at the end of the inspiratory phase. the PIP is a determined by both airway resistance and compliance . Is the main pressure to deliver the Tidal Volume. By convention, all pressures in mechanical ventilation are reported in “cm H2O.” It is best to target a PIP < 35 cm H2O. Positive End Expiratory Pressure (PEEP)  is the positive pressure that remains at the end of exhalation. This additional applied positive pressure helps prevent atelectasis by preventing the end-expiratory alveolar collapse. PEEP is usually set at 5 cm H2O or greater, as part of the initial ventilator settings.

15. Inspiratory & Expiratory Time Inspiratory time ( iTime )  is the time allotted to deliver the set tidal volume (in volume control settings) or set pressure (in pressure control settings). Expiratory Time ( eTime ) is the time allotted to fully exhale the delivered mechanical breath. I:E ratio, the inspiratory to expiratory ratio, is usually expressed as 1:2, 1:3, etc. The I:E ratio can be set directly, or indirectly on the ventilator by changing the : inspiratory time, the inspiratory flow rate, or the respiratory rate. By convention, decreasing the ratio means increasing the expiratory time. For example, 1:3 is a decrease from 1:2, just like 1/3 is less than 1/2.

16. Flow Peak inspiratory flow  is the rate at which the breath is delivered, expressed in L/min. A common rate is 60 L/min. If you increase the inspiratory flow , the breath is given faster, and that leaves more time for exhalation. Thus, inspiratory flow indirectly changes the I:E ratio.

17. Tidal volume (TV or VT) Tidal volume (TV or VT )  is the volume of gas delivered to the patient with each breath. The tidal volume is best expressed in both milliliters (ex: 450mL) and milliliters/kilogram (ex: 6 mL/kg) of predicted body weight.

18. Respiratory rate & Fraction of inspired oxygen (FiO2) Respiratory rate (RR or f, for “frequency”)  is the mandatory number of breaths delivered by the ventilator per minute.  20-25 per minute for children under 2 years and 15-20 per minute for older children(6). Fraction of inspired oxygen (FiO2)  is a measure of the oxygen delivered by the ventilator during inspiration, expressed at a percentage. Room air contains 21% oxygen. A mechanical ventilator can deliver varying amounts of oxygen, up to 100%.

19. Anatomy of a Breath Breathing is a periodic event, composed of repeated cycles of inspiration and expiration. Each breath, defined as one cycle of inspiration followed by expiration, can be broken down into four components, known as phase variables . Trigger : when inspiration begins Target : how flow is delivered during inspiration Cycle : when inspiration ends Baseline : proximal airway pressure during expiration

20. Trigger The trigger variable determines when to initiate inspiration. Ventilator-triggered breaths use time as the trigger variable. Patient-triggered breaths are initiated by patient respiratory efforts, utilizing pressure or flow for the trigger variable

21. Target The target variable regulates how flow is administered during inspiration. The variables most commonly used for the target include flow and pressure . Note that volume delivered per unit time, which is the definition of flow , is a target variable. high flow rate or low flow rate.

22. Cycle The cycle variable determines when to terminate the inspiratory phase of a breath. The term “to cycle” is synonymous with “to terminate inspiration . ” The variables most commonly used for the cycle include volume, time, and flow .

23. Baseline The baseline variable refers to the proximal airway pressure during the expiratory phase. This pressure can be equal to atmospheric pressure, known as zero end-expiratory pressure (ZEEP), in which the ventilator allows for complete recoil of the lung and chest wall, or it can be held above atmospheric pressure by the ventilator, known as positive end-expiratory pressure ( PEEP )

24. Mode of ventilation Types of mode in general Volume control : set volume and keep an eye on pressure. Pressure control : set pressure and keep an eye on Volume. Another element is that: Continuous : Machine not the patient doing work of breathing. Intermittent : the patient can breath between the breath set.

25. Mode of ventilation

26. Volume-Controlled Ventilation Volume-controlled ventilation, the target is flow , and the cycle is volume . Increasing flow reduces the time required to deliver the set tidal volume, which reduces inspiratory time for each breath. Decreasing inspiratory time for each breath will then increase expiratory time. Ventilator strategies to increase expiratory time in VCV: Decrease respiratory rate Decrease tidal volume Increase flow rate

27. Pressure-Controlled Ventilation In pressure-controlled ventilation, the target is proximal airway pressure , and the cycle is time . Inspiratory time can be directly reduced, leading to an increase in expiratory time. Tidal volume can be reduced by decreasing proximal airway pressure. With decreased tidal volume, less time is needed to fully expire the total administered tidal volume.

28. Ventilator variables

29. PRESSURE CONTROL (PCV) A mandatory amount of preset mechanical breaths at a preset peak inspiratory pressure are triggered and delivered. If the baby does not breaths spontaneously, a mechanical breath is automatically given at a preset rate and pressure. PCV is a very common mode of ventilation in newborn and pediatric patients.

30. Screen of Mechanical ventilation

31. Types of Waveforms Scalars are waveform representations of pressure, flow or volume on the y axis vs time on the x axis Loops are representations of pressure vs volume or flow vs volume

32. An arterial  blood gas  ( ABG )  test

33. Mechanical ventilation in simple way Mode : neonate to infant – PCV Fio2 : 100 PIP : 10 till TV :5-7 cc/Kg not reaching 10 cc/kg PEEP : 3 preterm . term 4-5 ( if O2 low can increase PEEP till 15 but we should give fluid and inotropic drugs if more than 10 ) Ti : preterm: 0.28 – 0.32 – Term: 0.3 – 0.40 ( you can increases ) R.R : 30 Triger : 1

34. An arterial  blood gas  ( ABG )  test ABG: you should know its arterial or venous : (Vein: saturation So2 : less than 90) After 10 to 20 min of intubation do ABG IF PO2 ( arterial: 80 TO 100 & vein 40 normal because you will add 40)LOW: Increase Fio2 then Increase PEEP IF PO2 High more than 100: Decrease FIO2 Till 60 then decrease PEEP PCO2 (Arterial 35 – 45 if venous + 10 ): do washing of Tube then do ABG More than 45: increase R.R if not respond till maximum then increase TV (PIP) if not increase till 8 cc/Kg if not responding (PEEP + PIP NOT MORE THAN 40) then increase Ti if not reduce PEEP bot not becoming Hypoxia. Low PCO2: vise versa is correct PIP and PEEP NOT SAME should be at lest 6 difference Sedation : Medazolam then Fentanyl

35. THANKS FOR YOUR ATTENTION