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Mech vent chap 41
WillWallace Mech Vent chapt 41
| Question | Answer |
|---|---|
| What is respiratory failure | inability of heart and lungs to provide adequate tissue oxygenation or removal of CO2 |
| Hypoxemic resp failure | PaO2 <60 on RA, regardless of CO2 |
| Hypercarbic resp failure | aka ventilatory failure or pump failure, PaCO2 >50 |
| disease states that can result in respiratory failure | acute resp fail; post op complications, sepsis, heart failure, pneumonia, trauma, ARDS, aspiration, COPD exacerbation, coma, neuromuscular |
| clinical symptoms of respiratory failure | restless, tachycardia, head ache, hypotension, poor chest expansion, confusion, cyanosis, depressed respiration |
| what are the most common causes of vent support | >WOB and muscle fatigue |
| what are the critical values for initiating vent support in a pt with decreased ventilation | PaCO2 >50 w/PH <7.2 |
| what are the critical values for initiating vent support in a pt with hypoxemia | PaO2 <50-60 on 40-50%, A-a (on 100%) >350, PaO2/FIO2 <200 |
| What are the critical values for initiating vent support in a pt with inadequate lung expansion | VT <500 mL/kg (norm 5-8), VC <10mL/kg (norm 65-75), RR >35 (norm 12-20) |
| what are the critical values for initiating vent support in a pt w/decreased muscle strength (tired) | MIP >-20cmH20 (norm -80-100), VC <10mL/kg (norm 65-75), MVV <2xVE (norm 120-180L/min) |
| what are the critical values for initiating vent support in a pt w/>WOB | VE >10 (norm 5-6), VD/VT >.6 (norm .25-.40) |
| what is impending ventilatory failure | severe air hunger, resp rate >35, diaphorisis, use of accessory muscles, w/normal or near normal ABG (or prior to ABG if condition is progressing) |
| critical values or indications of impending ventilitory failure | severe air hunger-RR>35, diaphorisis, use of accessory muscles, for neuromuscular-VC <1L or MIP <-20 to-30 |
| what is refractory hypoxemia | >PaO2 of less than 10 after increasing FIO2 by 20%, inadequate arterial oxygenation w/acceptable FIO2, PaO2 <60 (SaO2 <90) w/FIO2 >40-50%, P/F <300 ALI, P/F <200 ARDS. |
| Clinical values for ALI | P/F <300 w/bilateral infiltrates |
| clinical values for ARDS | P/F <200 w/bilateral infiltrates and Pul Cap Wedge press <18 |
| What is CPAP | spontaneous breathing with an elevated baseline pressure, small alveolar press to spont breathing pts on I and E to increase alv press, causes alveolar recruiting, benefit is lower FIO2 to maintain PaO2 |
| what are the indications for CPAP | refractory hypoxemia (PaO2 <60 on FIO2 >40-50%) with adequate ventilitory status (PaCO2 <45, PH 7.35-7.35) and to reduce the WOB in severe CHF. |
| What are the most common reasons for initiating vent support | BIG 4-APNEA, ACUTE VENT FAILURE (>CO2 W/PH <7.2), IMPENDING VENT FAILURE (RR >35 AND “CLINICAL PRESENTATION), SEVERE O2 PROBLEM (SHUNT, DIFFUSION DEFECT) |
| Goals of mechanical ventilation | 1-support and manipulate gas exchange (alv vent CO2 & PH), 2-increase lung volume (end inspiratory-end expiratory inflation and FRC), 3-reduce or manipulate WOB, 4-minimize cardiovascular involvement |
| What are the objectives of mechanical ventilation | reverse-hypoxemia, acute resp acidosis and ventilatory muscle fatigue, to relieve resp distress, prevent or reverse atelectasis, allow for sedation and neuromuscular blockade, < O2 consumption, maintain or improve CO, <ICP, stabilize chest |
| Common initial settings for VT are | ACNN- ARDS (4)6-8, COPD 8-10, Normal 10-12, Neuro 12-15 (all are based on IBW, ideal body weight) |
| Common initial setting for RR are | ACNN- ARDS 12-15, COPD 10-12, Normal 10-12, Neuro 8-10 (all are based on IBW) |
| Common initial ventilator setting for normal lung are | VT 10-12 mL/kg (can go to 15 for big person), RR 10-12 (can go down to 6-10 if VT is increased for big person), Flow is based on Itime, Itime target 1 second, I:E 1:2 or 1:3, mode VC-SIMV, Peep 3-5, FIO2 40-50% (in doubt use 100%) |
| Common initial ventilator settings for ARDS | VT 6-8, RR 12-15 (can go to 30), Flow set to Itime, ITime target is 1.2 seconds, mode VC-CMV, PEEP 5-8, FIO2 100% |
| Common initial ventilator settings for COPD and status asthmaticus | before venting COPD pt always try bilevel or bipap, VT 8-10, RR 10-12, Flow set to IT, IT target .8 to maximize Etime, mode VC-SIMV, FIO2 60-100, peep 3-5 |
| Common initial ventilator settings for Post Op pt | same as norm |
| Common initial ventilator setting for Neuromuscular Diseases | VT 12-15, RR 8-10, Flow/ITime target 1 second, Peep 3-5, FIO2 40-50% |
| Common initial ventilator setting for head injury | same as normal, but may adjust after 24 hours for increased ICP, hyperventilation to target CO2 of 25-30 to reduce ICP (<CO2 will cause vasoconstriction and <blood volume therefore reducing ICP |
| Common initial ventilator setting for Unilateral disease | to prevent ventilation from going only to healthy lung, use Karlan's ETT and add second machine, set one lung to ARDS and good lung to ½ normal settings except RR increase to 12-15 to compensate for smaller VT. Or use HFJV high freq jet vent. |
| Common initial ventilator setting for spinal cord injury | set to normal lung |
| what is a bronchopleural fistula | persistent air leak into the pleural space. Caused by trauma, surgery or invasive procedure like central line or from infections |
| Management of bronchopleural fistula on ventilated pt | assess leak size by measuring inspired versus expired VT, BFV need chest tube, VC not working change to high frequency, also keep PEEP to minimum or 0, and small VT 4-8, may need surgical repair. |
| What is optimal flow | 40-80 L/min, set to meet pt inspiratory demand (so spont breaths will have enough flow and pt will not have to work to hard) |
| Who benefits from higher flows | pts with >RAW like COPD, shorter Itime provides longer Etime to prevent airtrapping |
| Who benefits from lower flows | ARDS, longer IT helps recruiting |
| Constant flow waveform in VC | square or rectangular |
| WHAT IS BEST WAVEFORM FOR ARDS | DECENDING |
| what are the hazards of a short IT (high flow) | higher peak pressures and poor gas distribution |
| what are the hazards of longer IT (slower flows) | increased Paw that can lead to cardio effects, shortens Etime, long ITime can cause airtrapping |
| How do we shorten the Itime on a ventilated pt | increase the flow |
| What are the parameters that must be set on a mech vent | mode, VT, RR, I:E ratio, Flow, VE, PEEP, Trigger/Sensitivity, FIO2, Alarms |
| Setting flow if IT is 1 second (works on all machines except Servo) | F equals VTx60, so for VT of 700cc, if IT is 1 second then .700x60 is a flow of 42L/min |
| Inverse ratioventilatio IRV | IT is longer than ET |
| compication of IRV | MAWP increases significantly, >VD, <Venous return, <CO, >autoPEEP |
| when would an IRV be used | ARDS (rare) |
| Alv VE | VA eq (VT-VD)xRR |
| advantages of NPPV (noninvasive positive pressure ventilation) | avoid intubation and assoc complications, preserves natural defenses, pt comfort, maint speech and swallow, less sedation, intermittent use |
| disadvantages of NPPV | pt cooperation needed, limits acess to airway and suctioning, mask discomfort, air leak, transient hypoxemia from lost mask, bipap limit to 20-30, time consuming |
| who are best pts for NPPV | sleep apnea, acute COPD exacerbation, premature extubation, acute resp failure, CHF |
| conraindications of NPPV | cant tolerate or poor mask fit, secretions, severe hypoxemia, severe acidosis, hypotension, upper aw obstruction, prone to aspirations, need airway protection |
| what is full ventilatory support | mechanical support such that all energy necessary for effective alv vent is provided-key is to set VT and RR to ensure a minimum effective level of alv vent (vt10-12 rr 10-12) |
| Partial ventilatory support | using vent settings that require pt to provide some of the support (simv rates <10) |
| what modes allow for effective spontaneous breathing | SIMV, PSV, VS (volume support), APV (adaptive support) |
| 3 ways to trigger a breath are | time, flow and pressure |
| PC-CSV | pressure controll-cont spontaneous ventilation |
| critical values for specific physiological to initiate vent support | RR>35, VT <300 ml, RSBI >105 (RR/VT), MIP >30cmH2O, VC <1L (15-20mL/kg) |
| ABG consistant to mech vent | PaCO2 >45-50 w/corresponding decrease in Ph, hypoxemia w/supplimental O2, PaO2 <60 w/FIO2 >40-50% |
| initial vent setup decisions | indication, noninvasive/invasive, press/volume, partial/full support, Mode-AC, SIMV w/ or w/o PS, PSV, PSV, PCV, dual control |
Created by:
williamwallace
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