APRV Airway pressure release ventilation • ASB Assistedspontaneousbreathing • ASVassisted spontaneous ventilation • ASV Adaptive supportventilation • ASV assisted spontaneous ventilation. • ATC Automatic tube compensation • Automode Automode • BIPAP Bilevel Positive Airway Pressure • CMV Continuous mandatory ventilation • CPAP Continuous positive airway pressure • CPPV Continuous positive pressure ventilation • EPAP Expiratory positive airway pressure • HFV High frequency ventilation • HFFI High frequencyflowinterruption • HFJV High frequencyjetventilation • HFOV High frequencyoscillatoryventilation • HFPPV High frequency positive pressureventilation • ILV Independent lung ventilation • IPAP Inspiratory positive airway pressure • IPPV Intermittent positive pressureventilation • IRV Inversed ratio ventilation • LFPPV Low frequency positive pressure ventilation • MMV Mandatory minute volume • NAVA Neurally Adjusted Ventilatory Assist • NIF Negative inspiratory • NIV Non-invasive ventilation • PAP Positive airway pressure • PAV and PAV+ Proportional assist ventilation and proportional assist ventilation plus • PCMV (P-CMV) Pressure controlled mandatory ventilation • PCV Pressurecontrolledventilationor • PC Pressure control • PEEP Positive end-expiratory pressure • PNPV Positive negative pressure ventilation • PPS Proportional pressure support • PRVC Pressure regulated volume controlledventilation • PSV Pressure Support Ventilationor PS • (S) IMV (Synchronized) intermittent mandatory ventilation • S-CPPV Synchronized continuous positive pressure ventilation • S-IPPV Synchronized intermittent positive pressure ventilation • TNI Therapy with nasal insufflation • VCMV (V-CMV) Volume controlled mandatory ventilation • VCV Volume controlled ventilationor VCVS Volume Support
Concepts and Modes of Mechanical Ventilation Spontaneous Breathing Mechanical Ventilation Pressure CMV Time SIMV Pressure Time Bivent Pressure Time APRV Pressure Time CPAP Pressure Time
Positive Airway Pressure Can Be Either Pressure or Flow Controlled—But Not Both Simultaneously Dependent Variable Set Variable Set Variable Dependent Variable
Volume Ventilation Tidal volume, is not affected by the rapidly changing pulmonary mechanics Compliance Pressure Ventilation:Volume Ventilation: Decreased Tidal VolumeIncreased Pressure Volume Volume Pressure Pressure
Press. Control & Press. Support Variable flow Reduced WOB Max Palveolar = Max Pairway (or less) Palveolar controlled Variable Inspirationtime & pattern (PS) Better with leaks Volume Control Consistent TV changing impedance Auto-PEEP Minimum min. vent. (f x TV) set Variety of flow waves Pressure vs. Volume Ventilation:Advantages
Press. Control & Press. Support Variable tidal volume Too large ortoo small No alarm/limit for excessive TV (except some new gen. vents) Some variablity in max pressures (PC, expir. effort) Volume Control Variable pressures airway alveolar Fixed flow pattern Variable effort = variable work/breath Compressible vol. Leaks = vol. loss Pressure vs. Volume Ventilation:Disadvantages
Combination “Dual Control” Modes Combination or “dual control” modes combine features of pressure and volume targeting to accomplish ventilatory objectives which might remain unmet by either used independently. Combination modes are pressure targeted Partial support is generally provided by pressure support Full support is provided by Pressure Control
Newer Ventilator Dual Modes: Summary: • Combined methods of press. & volume ventilation may replace standard volume ventilation. • Prudent use of high pressure limits (and volume limits if available) and careful monitoring can decrease disadvantages of combined modes. • BiLevel (NPB 840) • Duopap (Hamilton) • APRV (NPB 840, Drager E-4 & E-2 dura) • Pressure targeted strategy & spontanous Breathing • can fit lung protective criteria
Lung protective strategies’ influence on ventilators & modes: • Lung protective strategies may include: • Control of peak alveolar press. (e.g. < 30 H2O)or low TV (e.g. 6 ml/kg IBW) • PEEP above lower inflection point* • Peak pressure below upper inflection point* • * of static compliance curve
New Modes of Mechanical Ventilation: Bi-level ventilation methods • Ventilation methods that allow spontaneous breathing at two airway pressures: • BiPAP (Drager E-4 & E-2 dura) • BiLevel (Respironics) • Duopap (Hamilton)
New Modes of Mechanical Ventilation: Background • Introduction of the microprocessor-controlled ventilator • Better control of flow & exhalation valves • Increased monitoring capabilities • Increased pt-ventilator interaction • “Dual modes” of ventilation introduced From Mosby’s R. C. Equip., 6th ed. 1999.
Spontaneous Breaths Spontaneous Breaths P T Duopap Ventilation • Uses two levels of pressure for two time periods • Mandatory breaths at the higher pressure are time cycled • Spontaneous breaths can be pressure supported From PB product lit.
PEEPHIGH Synchronized Transitions PEEPLOW THIGH P TLOW Synchronized Transitions T Duopap Ventilation • Uses 2 pressure levels for 2 time periods • PEEPlow & PEEPhigh, Thigh and Tlow • Patient triggering & cycling can change phases From PB product lit.
PEEPH PEEPHigh + PS Pressure Support P PEEPL Duopap Ventilation • Pressure support may be applied at both pressures during a spont. breath • If PS is set higher than PEEPH, the PS pressure is applied to a spontaneous effort at upper pressure From PB product lit.
Spontaneous Breaths Pressure Support P T Duopap Ventilation • If PS is set lower than PEEPH, PS is applied to patient efforts at the lower pressure, PEEPL From PB product lit.
Inspiration pressure - pinsp End expiratory pressure - PEEP Decelarating flow Tidal volume - vt BIPAP Biphasic Positive AirwayPressure - pressure controlled mode - mandatory ventilation for patients without spontaneous breathing activities - spontaneous breathing activities are possible Trigger synchronized BIPAP- breath or PS above the CPAP-level or without PS - Settings: FiO2, pinsp, f, tinsp, CPAP (PEEP), PS-level, Ramp - add. settings: ATC, Apnoe ventilation, Flow trigger
APRV (airway pressure release ventilation) • Airway Pressure Release Ventilation • Like BiPAP/BiLevel but time at the lower pressure (“release time”) is usually short, 1-1.5 seconds • Spontaneous breathing still allowed throughout low & high pressures
APRV • Airway Pressure Release Ventilation From Mosby’s R. C. Equip. 6th ed. 1999.
APRV AirwayPressure Release Ventilation - pressure controlled mode - mandatory ventilation for patients without spontaneous breathing activities - spontaneous breathing activities are possible - Settings: FiO2, phigh, plow, thigh, tlow, Ramp - add. settings: ATC, Apnoe ventilation Inspiration pressure - phigh End expiratory pressure - plow
Evidence-based guidelines American college of chest physicians American Association for Respiratory Care American college of emergency physicians American thoracic society Australian and New Zealand intensive care society Society for Critical Care Medicine European society of intensive care medicine European respiratory society ARDS Network
Evidence Base for Newer Modes of Mechanical Ventilation:Background From: Branson & Johanningman, 2004:RC,49:7, 742-760.
Patient Management • Semi recombinant position 450 VAP • Prone Position • Conservative fluid therapy 1 B 1 C 1 B
Weaning Strategy • SBT Grade A • Repeat SBT Grade A • Management of Failed SBT Grade B • Sedation protocols ( continuous or intermittent with daily awakening Grade B • Weaning protocols T pieces or electronic protocols Grade A
Modes allowing Spontaneous Breathing 2 CMV suppress SB activity by hyperventilation, sedation or muscle relaxation. Hyperventilation and respiratory alkalosis result in • decrease of cardiac out put • cerebral vasoconstriction • increased oxygen consumption in tissue • broncho-constriction • significant changes in ventilation/perfusion ratio V/P Hudson L. D., R. S. Hurlow, K. e. Craig, D. 1. Pierson. 1985. Am Rev RespirDis 132:1071-1074 Culpepper J. A., J. E. Rinaldo, R. M. Rogers. 1985. Am Rev RespirDis 132:1075-1077
Modes allowing Spontaneous Breathing 3 In comparison to an initial period of controlled ventilation for 72 hours followed by weaning, maintained SB with APRV/BIPAP is associated with significantly • fewer days on a ventilator, • earlier extubation • shorter stays in the ICU PutensenC., S. Zech , 1. Zinserling. 1998.. Am 1 RespirCrit Care Med 157:A45
Modes allowing Spontaneous Breathing 4 The influence of (CMV), (IMV) and (BiPAP) on duration of intubation and consumption of analgesics and sedatives in adult cardiac surgery. 596 post cardiac-surgery patients. 87 Patients were randomized to the 3 groups Uneven randomization CMV 123 pts, IMV group 431 pts, and biphasic CPAP group only 42 pts. Pts in the biphasic CPAP group had about 3–4 h shorter duration of intubation. Pts in IMVor biphasic CPAP required less sedation and analgesia than CMV Conclusion : maintenance of spontaneous breathing during biphasic CPAP improved patient comfort and thus reduced pain and anxiety. Rathgeber et al, 1997 Eur J Anaesthesiol;14(6):576–582.
Modes allowing Spontaneous Breathing 5 Comparison of ventilatory and hemodynamic effects of BIPAP and SIMV/PSV for postoperative short-term ventilation in patients after coronary artery bypass grafting. 24 patients after CABG no difference in gas exchange or hemodynamic variables. PIP was lower with BIPAP than with SIMV/PSV. Kazmaier S, Rathgeber J, Buhre W, Buscher H, Busch T, Mensching K, Sonntag H Eur J Anaesthesiol 2000;17(10):601–610
Duopap: Proposed advantages • Positive attributes of Duopap: lung protective ventilation • Decelerating variable flow • Spontaneous breathing • Improvement of pulmonary gas exchange • Decrease in the work of breathing Putensen et al 1999, Am 1 Respir Crit Care Med 159:1241-1248 • Improvement in cardiovascular effects and organ perfusion ( kidney, liver and splanchnic area) Hering and Putensen. 2000. Am J Respir Crit Care Med 161:A549 Bonnet et al 1982 . Crit Care Med 15:106-112 • Automatic weaning ??? ASV