Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content ++Table Graphic Jump Location|Download (.pdf)|PrintTidal volume (VT)Initially choose 8–10 mL/kg IBWAvoid high volumes to prevent barotrauma↑VT = ↑ MV and ↓ Paco2 and ↑ pHIf ARDS/ALI is present, use 6 mL/kg IBWRespiratory rate (RR)12–14 breaths/min usually adequate↑ RR = ↑ MV and ↓ Paco2 and ↑ pH, but beyond a certain point, dead space ventilation and risk of breath stackingFraction of inspired oxygen (FiO2)Start at 1.0 and taper down quickly to achieve a goal Pao2 of >60 mm Hg and O2 saturation of >90%Inspiratory flowUsually 40–60 L/min↑ Flow = ↓ inspiratory time and ↑ expiratory time, thus ↓ I:E ratioUseful in obstructive airways disease to decrease auto-PEEP, be careful though about the increase in peak airway pressurePositive end-expiratory pressure (PEEP)Typically set at 5 cm H2O↑ PEEP (up to 20–24 cm H2O) = ↑ oxygenation in ALI/ARDSMay lead to decreased venous return/hypotension, increased plateau pressure/barotrauma, may increase ICP (in theory) IBW, ideal body weight; ARDS, acute respiratory distress syndrome; ALI, acute lung injury; I:E ratio, inspiratory to expiratory ratio; ICP, intracranial pressure. ++ Trigger: What signals the ventilator to initiate the inspiration? Time or patient effort (pressure or flow)Target (limit): What limits/governs the airflow during inspiration? Pressure or flow or volume (not time)Termination (cycle): What signals the ventilator to stop the inspiration? Time or pressure or flow or volume ++ Mandatory—The machine triggers and/or cycles the breathSpontaneous—Patient triggered and cycled (the patient determines the VT); may be assisted or unassistedAssisted—The patient triggers the spontaneous breath and the machine does at least some of the work. The airway pressure rises above the baseline pressure (e.g., pressure support ventilation) ++ ++ Volume-cycled ventilation: Controlled mechanical ventilation (CMV)—rarely used nowadays in the ICU Time triggered, preset RR and VT, the patient cannot trigger any extra breathsThe patient should be heavily sedated/paralyzedAssist control/volume control (AC/VC)—most common mode Time and patient triggered, preset RR and VT. Patients can trigger additional set tidal volumes; they do not necessarily need to be sedated or paralyzed. Beware of hyperventilation and respiratory alkalosis.Intermittent mandatory ventilation (IMV)/synchronized intermittent mandatory ventilation (SIMV)—may also be used as a weaning mode (not routinely used today, may actually prolong the weaning process) IMV: time-triggered mandatory breaths, preset RR and VT. In between breaths, the patient can take additional spontaneous assisted breaths with a chosen pressure support (the VT varies with the effort).May lead to breath stacking (mandatory breath on top of a spontaneous breath).SIMV: similar to IMV, but the mandatory breaths are machine (time) or patient triggered, providing synchrony with the patient's effort and eliminating breath stacking. ++ Flow-cycled ventilation: Pressure support ... Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.