Overview of Ventilator Modes VC - Volume Control (a.k.a. assist control volume) -

Mechanical Ventilation: The Basics In the most basic sense, ventilator modes are defined by their control variable and settings. Breaths are triggered (started) and cycled (ended) by specific parameters, which are determined by the mode. While there are many modes to choose from, we will review the most basic below. Assist Control / Volume Control (AC/VC): • Delivers mandatory breaths at a fixed rate with a set volume (control) and allows spontaneous breaths to be triggered, but will assist those breaths with the full set volume as well (assist). • Volume Cycled, Delivers volume until set volume goal is reached • Volume: 6-8 cc/kg IBW, RR: depends on pt/scenario, PEEP: ARDSnet PEEP ladder, FiO2: goal spO2 > 88% Assist Control / Pressure Control (AC/PC): • Delivers mandatory breaths at a fixed rate with a set pressure for a set inspiratory time (control) and allows spontaneous breaths to be triggered, but will assist those breaths with the full set pressure and i-time as well (assist). • Time Cycled, Delivers set pressure for set inspiratory time (i-time) • PC: adjust to achieve Vte, RR: depends on pt/scenario, PEEP: ARDSnet PEEP ladder, FiO2: goal spO2 > 88% Pressure Support Ventilation (PSV): • Often, a "weaning" mode. Unlike in AC modes, in PSV all breaths are spontaneous with pressure to support the breath, but not "control" it (no mandated volume or i-time). • Flow Cycled, Delivers pressure support until flow has reached 25% of its peak • PS: 0-8, if in an SBT, RR: spontaneous, PEEP: 5-8, FiO2: goal spO2 > 88% Dr. Meredith Greer @EmmGeezee #MechanicalVentilation #Basics #Modes #Comparison #management #criticalcare

Ventilator Basics - Waveforms for Types of Breaths - Volume Control - Volume Assist - Pressure Control - Pressure Assist - Pressure Support #Ventilator #Waveforms #Breaths #diagnosis #pulmonary #mechanical #ventilation

Simplifying Mechanical Ventilation - Modes of Mechanical Ventilation - Comparison Table You now know many modes whether you realize it or not just by knowing the breath types (Controlled, Assisted, Supported) and how the breaths are delivered (Volume or Pressure). #Management #CriticalCare #Modes #Mechanical #Ventilation #Variables #Breaths #Comparison #Table #Volume #Pressure #Support #RebelEM #AssistControl

Volume Assist/Control Mechanical Ventilation How does this mode work? • Delivers a set volume of air with each breath; patient triggered breaths are identical to machine triggered breaths • Time and patient triggered, volume cycled, volume limited mode When should I use this mode? • Ensures that a patient receives a minimum MV • This is a good general-purpose mode; good for providing Lung Protective Ventilation (LPV) • PRVC mav have lower peak pressures; pressure modes may be more comfortable for select patients What do I need to monitor? • Need to make sure the peak pressure and plateau pressure do not exceed safe limits. • You will also need to monitor MV. If the patient is triggering excessively (or auto-triggering), they can become alkalemic. Choosing Initial Settings: • RR - Try to match the persons initial minute ventilation by selecting a rate to match their pre-intubation MV needs. • TV- Use 8cc/kg PBW and adjust as needed. For patients with ARDS (or at high risk) consider starting at 6cc/kg PBW. • Start with low PEEP and high Fi02 and wean to maintain SpO2 goal (typically > 90%). - Nick Mark MD @nickmmark #volume #assistcontrol #mechanical #ventilation #AC #criticalcare #pulmonary

(S)CMV - Synchronized Controlled Mechanical Ventilation Summary Most Similar to "AC/VC" Basic Set Parameters: 1) Rate 2) Tidal Volume 3) PEEP 4) FiO2 What's Happening: - The ventilator will deliver breaths of the set volume at a set rate. - If the patient initiates a breath the ventilator will deliver the full set volume. Best for: - ARDS & patients that are sedated or inactive Downside: - Uncomfortable for patients with respiratory drive (pt/vent asynchrony) - May result in hyperventilation in patients with respiratory drive. Advanced Parameters: - Can adjust I:E time, patient trigger type & sensitivity, flow pattern. Casey Albin, MD @caseyalbin #SCMV #Synchronized #Controlled #Mechanical #Ventilation #management #pulmonary

Basics of Mechanical Ventilation M. Daniyal Hashmi, MD @MDaniyalHashmi1 #Ventilator #Modes #Ventilation #CriticalCare #Management #Mechanical #Basics

APVcmv - Adaptive Pressure Ventilation - Controlled Mechanical Ventilation Summary Most Similar to PRVC - Pressure Regulated Volume Control Basic Set Parameters: 1) Rate 2) Target Tidal Volume 3) PEEP 4) FiO2 What's Happening - The ventilator adapts to the exhaled volume and in doing so assesses plateau pressure and static compliance. - The vent finds the correct pressure to deliver the desired volume. Baseline pressure is constant Best for: - Passive or partially active patients - The more work the patient does the less support it gets from the ventilator. - May be more comfortable for patients Downside: - May be uncomfortable for patients with a strong resp drive or neurogenic breathing patterns - Active patients may get more than set target minute ventilation (hyperventilate) Troubleshooting - If hyper/hypo-ventilating: - Confirm the height/ IBW are correct as the target tidal volume may be too high / too low (respectively) - Can adjust the I:E ratio, patient trigger and sensitivity, rise time Assess: Pressures generated by vent to hit the target volume Casey Albin, MD @caseyalbin #APVcmv #APV #Adaptive #Pressure #Mechanical #Ventilation #management #pulmonary

An Introduction to Mechanical Ventilation: This is a simplification of the general principles underlying the most common ventilator modes. For more detail, see the articles cited in the reference #Management #EM #PCC #Mechanical #Ventilation #Control #Variable #Breath #Sequence #Overview #Ddxof

ASV - Adaptive Support Ventilation Summary Basic Set Parameters: 1) Target MV (80-120%) 2) PEEP 3) FiO2 What's Happening: - Input height (IBW) to determine ideal minute ventilation. The vent attempts to achieve this MV w/ lowest amount of work by optimizing 1) Pinsp (pressure with each breath) 2) Rate, which depends on the # of breaths the patient initiates. - Patients can be almost completely dependent to completely spontaneous. Best for: - Patients with some respiratory drive - Patients with no significant pulmonary pathology Downside: - While a "weaning" mode, it's hard to know exactly how reliant the patient is on the vent. - Limited control. Not ideal for patients with ARDS, COPD, asthma or other sig pulm pathology Troubleshooting: - Confirm the patients height and IBW are entered correctly. - Decreasing the % of predicted needed MV can mitigate hyperventilation but if <80% choose different mode - If pt apneic on SBT after being on ASV, it's like they were hyperventilated Assess: - No. of spontaneous breaths - Degree of support for delivered breaths Casey Albin, MD @caseyalbin #ASV #Adaptive #Support #Mechanical #Ventilation #pulmonary

Work Shifting - Mechanical Ventilation Why the new term: Synchrony issues, by definition, have to do with timing. Thus, "flow asynchrony" is a misnomer. During inspiration (i.e, the period between trigger and cycle) the main issues are not related to timing but to work of breathing. Work Shifting: When Pvent and Pmus are active together, some portion of the total work is done by the ventilator and some by the patient. Explained: We use pressure, Pvent and Pmus, to demonstrate the relation between the mode of ventilation and the patient. See next page graph. It is the same relationship for pressure as for work. However the term work is more accurate. We can calculate work from the equation of motion. The units are joules or joules per unit of tidal volume (J/L). We described a Work Shift Index to quantify the amount of work shifted from the ventilator to the patient. Here depicted: If patient is on CPAP, with no ventilator assistance, the work by the ventilator W vent is zero and all the work is done by the patient W thus a Work Shifting Index, WS/ = 100%. See graphic for VC-CMVs and Pmus interactions Dr. Eduardo Mireles-Cabodevila @emireles_c #WorkShifting #Mechanical #Ventilation #Troubleshooting #diagnosis #criticalcare #pulmonary