Flow Review 2023 PDF Georgia State University
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Uploaded by ErrFreeKazoo
Georgia State University
2023
Prof. Battey-Muse
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Summary
This document is a review of flow, minute ventilation, tidal volume and respiratory rate. It details the various components of a breath, including minute ventilation, tidal volume, respiratory rate, total cycle time, and I:E ratio. It also explains how flow is affected during inspiration and how changes in patient respiratory status impact the components. Useful for respiratory therapy students.
Full Transcript
Georgia State University RT 3111/6111 Flow Review Prof. Battey-Muse Learning Objectives Mathematically define the different components of a breath including Minute Ventilation Tidal Volume Respiratory Rate Total Cycle Time I:E Ratio Explain how flow is affected in eac...
Georgia State University RT 3111/6111 Flow Review Prof. Battey-Muse Learning Objectives Mathematically define the different components of a breath including Minute Ventilation Tidal Volume Respiratory Rate Total Cycle Time I:E Ratio Explain how flow is affected in each phase of inspiration Discuss how changes in equation components are effected by changes in patient respiratory status Minute Ventilation (MV or Ve) Total lung ventilation per minute Adult normal: 6000 – 10000 mL/min (6-10L) Ideal based on patient gender and height Is affected by disease state Different patients can have different “normal” Minute Ventilation (MV or Ve) Minute Ventilation Vt = 500 cc or mL (MV)= RR = 12 bpm 500 mL x 12 bpm = 6000 mL = 6L Tidal Volume (Vt) Vt = 500 mL X RR = 22 bpm 500 mL x 22 bpm = 11000 mL = 11L Rate(RR) Vt = 400 mL RR = 12 bpm 400 mL x 12 bpm = 4800 mL = 4.8 L Tidal Volume (Vt) Total lung ventilation per breath Adult normal: 5 – 7 mL / kg IBW IBW takes height and gender into account Range can differ based on patient age, exertion level, and disease process Tidal Volume (Vt) Tidal Volume (Vt) = Ve = 10 L RR = 14 bpm 10 L / 14 bpm = 714 mL Minute Vent (Ve) Ve = 10L RR = 20 bpm Rate (RR) 10L / 20 bpm = 500 mL Remember: 1L = 1000 mL Respiratory Rate (RR or f) Number of total breath cycles per minute Adult normal: 12 – 18 breaths per minute (bpm) Range can differ based on patient age, exertion level, and disease process Respiratory Rate (RR or f) Respiratory Rate (RR) = Ve = 12 L Vt = 500 mL 12 L / 500 mL = 24 bpm Minute Vent (Ve) Ve = 12 L Vt = 1000 mL Tidal V0lume (Vt) 12 L / 1000mL = 12 bpm Ve = 8 L Vt = 400 mL 8L / 400 mL = 20 bpm Total Cycle Time (TCT) Amount of time needed to complete one cycle of inspiration and expiration Adult normal: 3.3 – 5 seconds Total Cycle Time (TCT) Total Cycle Time (TCT) = RR = 30 bpm 60 s / 30 bpm = 2 s 60 seconds RR = 24 bpm 60 s / 24 bpm = 2.5 s Rate (RR) RR = 15 bpm 60 s / 15 bpm = 4 s Total time of insp + exp Total Cycle Time (TCT) Total Cycle Time (TCT) = Inspiratory Time = percent or portion of TCT spent on inspiration Inspiratory Time + Expiratory Time = percent or portion of TCT spent on Expiratory Time expiration I:E Ratio I:E Ratio 1:2 is a normal I:E ratio for a spontaneously breathing adult Inspiratory Time (I) ^^^ flow demands = shorter : iTime 1:3 or 1:4 = Less time in insp, Expiratory Time (E) more time in exp Minute Ventilation (MV or Ve) Minute Ventilation Vt = 500 cc or mL (MV)= RR = 12 bpm 500 mL x 12 bpm = 6000 mL = 6L Tidal Volume (Vt) Vt = 500 mL X RR = 22 bpm 500 mL x 22 bpm = 11000 mL = 11L Rate(RR) Vt = 400 mL RR = 12 bpm 400 mL x 12 bpm = 4800 mL = 4.8 L 500 mL x 12 bpm = 6000 mL = 6L 500 mL x 22 bpm = 11000 mL = 11L RR = 12 bpm RR = 22 bpm 60 s / 12 bpm = 60 s / 22bpm = 5 seconds TCT 2.73 seconds TCT ~1:2 I:E ~1:2 I:E 1.5 s insp 0.91 s insp 3.5 s exp 1.82 s exp Time Constants Inspiratory time is broken into 5 time constants First 63% of breath is pulled in by the 1st time constant Higher flow needs to be generated by the patient to pull this larger volume Flow > delivers > Volume Assume a 500 mL tidal volume A higher flow is needed to deliver 315 mL vs 10 mL if time remains 1st time constant: constant 315 mL delivered 2nd timeconstant: 3rd time 4th time 5th time constant: 110 mL delivered constant: constant: 10 mL delivered 50 mL 15 mL delivered delivered Flow Peak flow = highest flow utilized to deliver a minute ventilation May be greater than the total Minute Volume Higher flow in the beginning of the breath, lower flow towards the end of the breath Rule of thumb Minute volume x 3 = peak inspiratory flow needed to provide MV At baseline. Are our pts in the hospital at baseline? Pts in distress may need as much as 5 x MV in flow Distress = ^ RR = shorter iTime= more flow needed Air hungry/Flow hungry Questions?
