1. Michel Boivin

2.  Review basics of mechanical ventilation  Compare different modes of mechanical ventilation  Determinants of oxygenation and ventilation  Lung protective ventilation  Liberation from mech vent.

3.  1. Protect airway  2. Ventilate (clear CO2)  3. Oxygenate  4. Because the ED were bored

4.  “Servo i” brand ventilator  Now actually owned by Maquet  Being phased out

5.  Puritan-Bennett 840  Soon to be replaced by the 960  Not as good at APRV as Servo I  In MICU

6.  Currently some in TSI  Will be in MICU soon  Not too different from 840  Better at APRV/ Bivent

7.  Patient comes to the ED with an overdose of benzos and is intubated for airway protection, was ventilating and oxygenating fine. We will chose initial settings. What mode will improve this patients outcome?  A) Pressure-Targeted SIMV  B) Pressure – Targeted A/C  C) Volume Targeted SIMV  D) Volume Targeted A/C  E) Pressure Support  F) APRV / Bivent  G) Automode  H) PRVC

9.  Both Timed modes, you will get a set number of breaths (the set rate)  When you trigger more breaths than the set rate in A/C mode you get more of the same breaths (Volume or Pressure Targeted)  In SIMV when you exceed the set rate you get pressure support breaths.  It makes no sense to get 2 different types of breaths and studies have shown SIMV weaning prolongs mechanical ventilation

10.  Can’t have one without the other  If you control pressure volume is variable

12. Volume You set: – Tidal volume -In our ventilators we set inspiratory time which determines flow rate. Delivery of the breath stops when set volume delivered (termination signal) - Airway pressure may vary with effort, lung mechanics Pressure You set: – Inspiratory Pressure (deltaP) Flow rate goes to maximum flow until set pressure is reached. - Inspiratory time is also set by the user and determines cycling. Volume may vary depending on effort and lung mechanics

13.  Flow curve is decelerating; flow goes in until set pressure is reached..  The Pressure vs. Time curve exhibits a square pattern  The Volume vs. Time curve shows an initial sharp rise due to higher flow. However, the slope then tapers, indicating lesser amount of volume

14.  Flow set to deliver set volume, flow curve is square indicating that flow goes in to set volume.  Guaranteed minute ventilation by setting tidal volume.

15.  All breaths are spontaneous, none are mandatory  The level of pressure supporting every spontaneous patient effort is set Breath is supported until flow decreases to approximately 25% of peak value.   Volume of each breath is variable  Comfortable mode for alert patient  Rate and tidal volume are not guaranteed and patient must have sufficient respiratory drive.  Can be used as part of spontaneous breathing trial as part of extubation process to overcome resistance of ETT.

16.  The RT is pretty excited about it.  New modes are mostly to sell ventilators.  Few studies show any outcome differences yet…

17.  Basically if volume and pressure mode had a baby  Basically makes alarms go off less often

18.  Proportional assist Ventilation (PAV)  Adaptive support ventilation  NAVA

19. Jet VentilationAPRV – Bilevel - Bivent  More used in pediatrics  Mode when conventional ventilation fails  Large randomized trials show no improvements in adults in ARDS, possibly worse.  Accepted use is failure of conventional ventilation in ARDS

20.  Don’t be misled!  Rarely is the solution to a patient having a problem tolerating the ventilator solved by changing the mode.

21.  What is the next question you need to ask to set up the ventilator?

22.  8 ml/ kg a good place to start  Almost all patients who are intubated are at risk for ARDS.  All patients with ARDS or at Risk for ARDS should be weaned down to 6 ml/ kg.  Get a tidal volume calculator

23.  You have set the tidal volume what initial rate will you choose? ◦ What is the dead-space ◦ What is the metabolic rate ◦ What is the serum bicarb ◦ If all of these are normal what rate will you choose

24.  Referred to wasted ventilation  Can be anatomic or physiologic  Means you have to breathe more to maintain same arterial pCO2  Means you need to set a higher rate

25. Metabolic rateAcidosis  If your metabolic rate is increased you will consume more O2 and produce more CO2 therefore need more minute ventilation  Fever and shivering most relevant causes in icu patients  If you need to compensate for a metabolic acidosis you need to set a higher rate to achieve a compensatory pco2

26.  Normal lungs, no acidosis: Rate 12  Severe acidosis, severe lung problem : Rate 24-30  In between Rate 20.  And … get a blood gas in 30 minutes.

27.  You set the rate to 20 and the tidal volume to 500. You get the ABG back in 30 minutes and it shows:  pH 7.60 pCO2 20 pO2 350 and Bicarb 24  What adjustment should you make?  A) rate to 10  B) rate to 18  C) rate to 40  D) Change tidal volume to 250  E) Change tidal volume to 700

28. To increase ventilation, increase rate, increase PIP, increase inspiratory time MINUTE VENTILATION = RATE x TIDAL VOLUME (Rate1 x Vt 1) x PCO2 1 = (Rate 2 x Vt 2) x PCO2 2 Or New Rate= Rate old x Vt old x PCO2 old/Vt new x PCO2 new

29. (Rate1 x Vt 1) x PCO2 1 = (Rate 2 x Vt 2) x PCO2 2 Or New Rate= Rate old x Vt old x PCO2 old/Vt new x PCO2 new  Our new rate = 20 X 500 X 20 / (40 X 500)  New rate = 10

30.  There is no limit on the number of blood gases you are allowed to obtain.

31.  What should you do? A) Reduce tidal volume B) Increase RR C) Increase PEEP D) Increase i-time E) Switch to bivent

32.  Patient’s ideal body weight is 62kg  Initial starting volume is 8 ml/kg - 500  This is titrated down within 2h to 6 ml/kg  6 ml/kg is 373 for this patient, 6 ml/kg

33.  Mild : P/F ratio 200-300  Moderate ARDS : P/F ratio <200  Severe ARDS : P/F ratio <125-150  What is the P/F ratio of a floor patient on 4l nasal cannula and with a pO2 of 65mmHG. (fiO2 for 4l NC is ~ 0.33)  Whoa…

34.  Your patient with ARDS is being ventilated at 6 ml/kg in volume- targeted assist / control mode. The RT tells you the peak pressure is 50 cmH2O.  What do you do next? ◦ A) Reduce Vt to 5 ml /kg ◦ B) Change to Pressure –Targeted Assist Control ◦ C) Create diversion / hide in broom closet ◦ D) Check plateau pressure

35.  Is close to the pressure the Alveolus “feels”  Correlates with barotrauma (loosely)  Should be kept under 30 cm/H20 in ARDS

36. Amato et al.,NEJM 2015

37.  You get called by nurse that patient is on Vt 6ml/kg, PEEP 10 and Fio2 70% and their O2 saturation is 88%, when it was 93 %  What do you do?  A) Increase PEEP  B) Increase FiO2  C) Diurese patient  D) Change to Bivent  E) Get a CXR

39.  Diffuse lung disease responds to increased airway pressure including CHF and ARDS.  Focal lung diseases (atelectasis, consolidation) generally do not.  Hypoxia from R-L shunting, pulmonary embolism also is not responsive to pressure.

40.  Increase oxygenation by: 1. Increase FIO2 2.Recruiting alveoli with positive end- expiratory pressure

41.  Pressure maintained in airways at end of exhalation  Total PEEP = extrinsic + intrinsic PEEP  Amount of intrinsic peep can be measured by occluding expiratory circuit on ventilator; this is your ‘auto-peep’  Increasing PEEP maintains further lung inflation, preventing collapse of alveoli  Useful in ARDS

43.  ARDS –Discussed  Obstructive lung disease – May need more time to exhale.

45.  1. Ventilators cause lung injury especially with high volume or pressure  2. Studies show that almost any intervention that reduces time on ventilator improves survival. (sedation studies etc…)

46. Exclusion Criteria for Daily Sedation Awakening Trial Patients with FiO2 > 60- 80 Peep >15 Continuous neuromuscular blockade Open chest Active myocardial ischemia Increased intracranial pressure Significant vasopressor use

47.  All patients that qualify should get spontaneous awakening trial.  If they meet criteria patients should get spontaneous breathing trials…  Spontaneous breathing trials can be done with either T piece or pressure support

48.  Patient gets SAT  If they pass they get SBT  If they pass SBT and are appropriate for extubation then they are extubated  Failed SBT=  RR/ Vt ratio >105 on PS 0 or 5  Develop Chest pain, ST changes or pulmonary edema  Develop severe agitation

49.  Characteristics of Breath: 1. 3 T’s: Target, Trigger, Termination 2. Common breath types: Assisted or Supported  Vent modes: Assist control, SIMV, Spontaneous / PSV

52.  problem with airways resistance.  obstruction of the tracheal tube, airway obstruction from secretions, and acute bronchospasm.  airways suctioning is indicated to clear secretions, followed by an aerosolized bronchodilator treatment if necessary.  Cough, biting, fighting

54.  Can be caused by a decrease in distensibility of the lungs and chest wall.  pneumothorax, lobar atelectasis, acute pulmonary edema, and worsening pneumonia or ARDS.  increased abdominal pressure can also decrease the distensibility of the thorax (tense ascites).  A patient with obstructive lung disease who becomes tachypneic can develop auto-PEEP, and this increases the peak and plateau pressures as well

55.  Set low PEEP and “high PEEP” (P-high, P low) plateau levels  Patient takes spontaneous breaths, which can be pressure supported  Duration of low PEEP and high PEEP (Thigh, T low) can be time-based or synchronized with patient effort

56.  Pressure targeted ventilation with long inspiratory time, and very brief expiratory time  Exhalation to a set PEEP of zero, though PEEP likely much higher as a result of intrinsic auto PEEP that develops from short exhalation.  In some settings APRV = BiLevel ventilation with a very long inspiratory time (high PEEP)and a very short expiratory time (low PEEP) (i.e. < 0.8 sec) to very low PEEP level (i.e. 0-5 cmH2O)

57.  Decrease T High Shorter T High means more release/min. No shorter than 3 seconds Example: T High 5 sec. = 12 releases/min T High 4 sec = 15 releases/min  Increase P High to increase  P and volume exchange. (2-3 cm H 2 O/change) Monitor Vt PIP (best below 30 cm H 2 O)  Check T low; if possible, increase T low to allow more time for “exhalation”  Increase T high (fewer releases/min)  Slowly! In increments of 0.5 to 2.0 sec.  Decrease P High to lower  P monitor oxygenation and avoid derecruitment  It may be better to accept hypercapnia than to reduce P high so much that oxygenation decreases

58.  Thought is that maintaining inspiration for long time helps open alveoli for ventilation  Less precise control of Vt – easy to > 6 ml/kg  Difficult to control minute ventilation  High Phigh can be deleterious for preload dependent patients

59.  Ventilator induced lung injury  Barotrauma  Dynamic hyperinflation/Auto peep  Ventilator associated pneumonia

60.  Normally, expiratory flow returns to the baseline prior to the next breath.  If expiratory flow does not return to the zero line and the subsequent inspiration begins below the baseline, auto-PEEP or air trapping is present.  Auto PEEP may result from inadequate expiratory time, too high of respiratory rate, long inspiratory time  Can be fixed by increasing inspiratory flow rate, decrease inspiratory time, to allow for longer exhalation.

61.  Bronchospasm, mucous plugging, airway inflammation increase airflow obstruction  Patients need prolonged time for exhalation  Dynamic hyperinflation can cause barotrauma and cardiovascular collapse, which is caused by intrinsic peep and elevated plateau pressures  Decrease respiratory rate, lower tidal volumes; allow permissive hypercapnia.  Can also increase inspiratory flow rate

62.  Ventilator, Tubing, Endotracheal Tube – Ventilator malfunction – Disconnection – Obstructed ETT or cuff leak – Insufficient rate, flow, pressure, other  Patient – Pain, anxiety, delirium, dyspnea – Cardiac ischemia, shock – Hypoxemia – Barotrauma

63. References 1. Esteban A, Frutos F, Tobin MJ, et al: A comparison of four methods of weaning patients from mechanical ventilation. N Engl J Med1995, 332:345–350. 2. Girard, T et al. (2008) Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): a randomised control trial. The Lancet. 371:126-34 3.Kollef, M et al.(1998) The Use of Continuous IV Sedation is Associated with Prolongation of Mechanical Ventilation. Chest. 114; 541-548 4. Girard, T and Ely, W. 2008. Weaning from Mechanical Ventilation. Chest PCCSU Oct 2008 5. Nava S, Ambrosino N, Clini E, et al: Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due tochronic obstructive pulmonary disease. Ann Intern Med 1998, 128:721–728. 6. Girault C, Daudenthu n I, Chevron V, et al: Noninvasive ventilation as a systematic extubation and weaning technique in acute-on chronic respiratory failure. A prospective, randomized controlled study. Am J Respir Crit Care Med 1999, 160:86–92. 7.Brochard L, Rauss A, Benito S, et al: Comparison of three methods of gradual withdrawal from ventilatory support during weaning from mechanical ventilation. Am J Respir Crit Care Med 1994, 150:896–903 8. Hess, Dean. Ventilator Modes Used in Weaning. Chest 2001;120;474S-476S