Lung Protective Ventilation Flashcards
Ptp=
Palv-Ppl
maintain (+) Ptp
increasingly (+)Ppl means increasingly (-) Ptp and favors atelectasis
maintaining a positive trans pulmonary pressure during surgery is dependent n maintaining
alveolar pressure
anesthesia and surgical effects on lungs
loss of muscle tone, cephalic displacement of abdominal contents, alveolar compression
elevated intraabdominal pressure, increased BMI, pneumoperitoneum, trendelenburg
transition from upright to supine decreases FRC by
.8-1L
induction agents reduce FRC by
.4-.5L
total reduction of FRC from supine and induction
1.2-1.5L
if FRC is impinging on closing capacity, atelectasis occurs
factors that contribute to alveolar collapse
position
induction
FiO2 (increased FiO2 is faster resorption behind closed airways)
maintenance (compliance)
emergence (high FiO2 promotes postop atelectasis, absence of CPAP means continued lung collapse)
ventilation induced Lung injury (VILI)
ventilator does not cause injury but the settings of the vent does (increased TV or pressures)
ventilation associated lung injury (VALI)
4 examples
specific to OR setting
volutrauma (damaged endothelium, decreased surfactant, increased cap leak)
barotrauma (damage from postitive pressure)
atelectrauma (repeated collapse and reinflatio of alveoli)
biotrauma (all of these 3 lead to this, inflammatory mediator release. bad cycle)
LPV initial maintenance settings
Low TV 6-8ml/kg IBW minimize FiO2 <30% individualized PEEP: 30% of BMI alveolar recruiemtn maneuvers I:E ratio 1:1.5
LPV emergence settings
FiO2 <80%
positive pressure ventilation, must be greater than closing pressure
elevated HOB to shift diaphragm caudad
Induction Strategies
goal is to attenuate anesthesia related changes
initial FiO2 100%
elevate HOB >30%
tightly sealed face mask- apply CPAP. use APL valve or CPAP mode on vent
OPA or NPA PRN
goals of maintenance anesthesia
restore lung volume with alveolar recruitment maneuver (ARM)
maintain lung volume and minimize atelectasis formation (individualize PEEP)
maximize lung compliance (use lowest possible drivingp pressure)
driving pressure=
Pplat-PEEP
PC-VG and PCV won’t have Pplat so use Pip
compliance =
TV/driving pressure
maintain SpO2 at
> or equal to 94%
purpose of maintenance FiO2 and SpO2
reduce resorption atelectasis, use SpO2:FiO2 curve as monitor to assess if we are maintaining open lung ventilation. SpO2:FiO2 ratio shows you if you’re exceeding critical opening pressure
at 21% if sats are less than 97%
we know greater than 10% intrapulmonary shunt is occurring
alveolar recruitment maneuvers
bag squeezing technique
ARRM through ventilator is ideal aka vital capacity maneuver on vent in CPAP mode
minimum recruitment pressure required for a BMI <30
40cmH2O
minimum recruitment pressure required for a BMI 30-40
40-50cmH2O
minimum recruitment pressure required for a BMI 40-50
50-55cmH2O
minimum recruitment pressure required for a BMI > or equal to 50
50-60cmH2O
initial setting of PEEP and purpose
BMI x .3 (to a max starting PEEP of 15)
purpose is to maintain end expiratory lung volume, reduce atelectasis formation, must be proceeded by ARM so you dont induce barotrauma
I:E ratio for a BMI <45
1:1.5
I:E ratio for a BMI >45
1:1 because they have increased pressure on chest and have faster expiration anyway
I:E ratio purpose
reduce airway pressures, increase homogenous ventilation
emergence goals
maintain open lung throughout emergence
minimize anesthesia induced changes during postop period
emergence FiO2 and purpose
maintain FiO2 less than or equal to 80 throughout
purpose is to reduce atelectasis formation
positive pressures ventilation during emergence
maintain CPAP and PEEP throughout
purpose is to prevent atelectasis formation and maintain open lung state
HOB elevation purpose
decrease chest wall compression and increase lung compliance
concerns for using postop excessive O2 use
activation of ROS
periphrealy/coronary vasoconstriction
decreased CO
absorption atelectasis
pressure volume loop
assessment of driving pressure or pressure required to deliver set volume
want to maximize volume delivered at lowest pressure. widening loop is bad and means downtrending compliance
flow volume loop
representation of expiratory flow. acute angle represents expiratory flow limitation
