9 Mechanical Ventilation

Question 1

how to approximate alveolar pressure

Answer 1

measure the plateau pressure with an end inspiratory pause in a passively breathing or paralyzed patient

Question 2

target plateau pressure

Answer 2

less than 30 cm H2O

Question 3

initial settings in pressure control

Answer 3

start with a pressure control of 10 cm H2O above PEEP and adjust pressure up and down to target tidal volume of 6-8 mL/kg ideal body weight

Question 4

remarks for patients who are not intubated for severe hypoxemia or obstructive lung disease

Answer 4

consider transitioning to pressure support (?) after a volume-targeted mode because the former may be more comfortable for the patient

Question 5

remarks on obese patients

Answer 5

obese patients and those with tense abdomen require higher PEEP
start at 8-10 cm H2O

Question 6

remarks on hyperoxia

Answer 6

hyperoxia increases patient mortality in a dose-dependent relationship.
Many recommend titrating the FiO2 to target an O2 saturation of no greater than 96% as soon as the patient recovers from the apneic induction period

Question 7

targets in sedation

Answer 7

target a Richmond Agitation-Sedation Scale (RASS) score of
-2 (awakens and makes eye contact to voice)
to 0 (awake, alert, and calm

Question 8

in patients with bilateral lug disease and at risk for ARDS, and the plateau pressure is above 30 cm H2O, what to do with tidal volume?

Answer 8

the tidal volume should be incrementally decreased by 1 mL/kg to as low as 4 mL/kg

these protective lower tidal volumes may lead to hypercapnea and acidemia although a pH of >7.20 is usually well tolerated

Question 9

other options in those with refractory hypoxemia and criteria for severe ARDS

Answer 9

neuromuscular blockade
prone positioning
pulmonary vasodilators
transfer to an ECMO-capable center

Question 10

remarks on ventilator care bundle

Answer 10

implement it in every patient ASAP. it includes:
-routine measurement of patient height to determine appropriate tidal volume for ventilation
-elevating the head of bed to at least 30 degrees
-decompressing the GI tract
-oral care with chlorhexidine solution

Question 11

remarks on sedation in mechanical ventilation

Answer 11

although often not an ED issue, ending sedation or using sedation holidays allow for more prompt return to spontaneous ventilation

Question 12

maneuvers for obstructive lung disease to prevent lung trapping

Answer 12

increase IFR (inspiratory flow rate)
*typically, it’s 60 LPM
*recommendation in COPD is 80-100 LPM

Question 13

Remarks on PEEP

Answer 13

improvements through increased PEEP are not immediate, so use incremental changes in pEEP of 2 cm H2O every 10-20 minutes rather than rapidly increasing or decreasing because there is potential for unanticipated hemodynamic, intrathoracic, or intrapulmonary changes

Question 14

other remarks in mechanical ventilation

Answer 14

decrease FIO2 quickly to avoid hyperoxia
start VTE prophylaxis approach
adequate sedation
but think early about Sedation holidays and Spontaneous breathing trials in patients expected to be housed in the ED for ≥24 hours

Question 15

ARDS definition

Answer 15

Berlin definition
onset with 1 week of a known clinical insult or new or worsening respiratory symptoms
bilateral opacities on chest imaging not fully explained by lobar/lung collapse or nodule
respiratory failure not fully explained by cardiac failure or volume overload
PF ratio ≤300 mm Hg with PEEP ≥5.0 cm H2O

Question 16

patients with these conditions are at risk for ARDS

Answer 16

pneumonia
sepsis
trauma
pancreatitis
shock state