Mechanical ventilation (main): Difference between revisions

Revision as of 20:59, 22 July 2011

Modes

CPAP

needs spont breathing pt
not for fatiguing pt
no back up rate

CONTROL MODE

only in OR
machine initiates and delivers breath
fixed rate and TV

ASSIST CONTROL (AC)

preset rate and TV
pt able to trigger additional breaths

SYNCH INTERM MANDATORY VENT (SIMV)

preset rate and TV synch to pt effort
for each additional breath triggered by pt- vent delivers variable TV depending on pt effort and condition of lung
because of pt effort- not recommended for tired or septic pt

PRESSURE SUPP0RT

use with SIMV or PEEP- not AC
preset boost during inspiration of spont gen breath

MODES

A/C = Assist Control

(helps instigated breaths, extra breaths all of set TV)
delivers preset breaths (full assisted tidal volume) in coordination with the respiratory effort
spontaneous breathing (above rate) is not allowed
beneficial for patients requiring a high minute-ventilation (reduces oxygen consumption and CO2 production of the respiratory muscles)
may worsen obstructive airway disease by air trapping or breath stacking

SIMV = Synchronous Intermittent Mandatory Ventilation

(senses not to give with breathing if present, extra breaths of pt's TV)
preset breaths in coordination with the respiratory effort
spontaneous breathing allowed between breaths
synchronization attempts to limit the barotrauma by not delivering a breath when already maximally inhaled (vs. IMV)

PS = Pressure Support

(controls via pressure, good if pressures getting too high)
limits barotrauma and decreases the work of breathing in the spontaneously breathing patient
level of pressure set (not TV) to assist spontaneous efforts
most ventilators allow back-up respiratory rate (in case of apnea)
mode of choice in patients whose respiratory failure is not severe and who have an adequate respiratory drive (improved patient comfort, reduced cardiovascular effects, reduced risk of barotrauma, and improved distribution of gas)

^For the paralyzed patient, there is no difference in minute-ventilation or airway pressures between A/C and SIMV

@@ Line 22: / Line 22: @@
 * use with SIMV or PEEP- not AC
 * preset boost during inspiration of spont gen breath
+==MODES==
+===A/C = Assist Control===
+#(helps instigated breaths, extra breaths all of set TV)
+#delivers preset breaths (full assisted tidal volume) in coordination with the respiratory effort
+#spontaneous breathing (above rate) is not allowed
+#beneficial for patients requiring a high minute-ventilation (reduces oxygen consumption and CO2 production of the respiratory muscles)
+#may worsen obstructive airway disease by air trapping or breath stacking
+===SIMV = Synchronous Intermittent Mandatory Ventilation===
+#(senses not to give with breathing if present, extra breaths of pt's TV)
+#preset breaths in coordination with the respiratory effort
+#spontaneous breathing allowed between breaths
+#synchronization attempts to limit the barotrauma by not delivering a breath when already maximally inhaled (vs. IMV)
+===PS = Pressure Support===
+#(controls via pressure, good if pressures getting too high)
+#limits barotrauma and decreases the work of breathing in the spontaneously breathing patient
+#level of pressure set (not TV) to assist spontaneous efforts
+#most ventilators allow back-up respiratory rate (in case of apnea)
+#mode of choice in patients whose respiratory failure is not severe and who have an adequate respiratory drive (improved patient comfort, reduced cardiovascular effects, reduced risk of barotrauma, and improved distribution of gas)
+^For the paralyzed patient, there is no difference in minute-ventilation or airway pressures between A/C and SIMV
 ==See Also==