Pulmonary Disorders I

Answer: B

According to the Berlin ARDS definition, the category

of acute lung injury was removed in favor of categoriz-

ing the severity of ARDS (Pao2/Fio2 less than 200 mm

Hg) (Answer A is incorrect). Because of the relative dif-

ference in mortality rates, mild and moderate ARDS

cases are less likely to benefit from therapeutic inter-

ventions, given the number needed to treat to show an

effective intervention (Answers C and D are incorrect).

In the trials evaluating prone positioning and cisatracu-

rium, patients with severe ARDS were the most likely

to benefit. Although the criteria used for severe ARDS

in these studies differed from those used in the Berlin

definition (both studies were initiated before publication

of the Berlin ARDS definition), a post hoc analysis shows

a survival benefit in favor of the group with the highest

mortality rate (Answer B is correct).

The Belin definition defines ARDS severity with Pao2/

Fio2 as one element of criteria. Comprehension of sub-

populations of ARDS is essential to apply published

clinical data among various therapies. Although not uni-

versally defined, the most commonly reported inclusion

criteria among landmark ARDS clinical trials (ROSE,

ACURASYS, DEXA-ARDS, etc.) was moderate to

severe ARDS criteria defined as Pao2/Fio2 less than 150

mm Hg (Answer C is correct; Answers A and B are

incorrect). Also, these trials did not define a lower limit of

ARDS severity (e.g., 50–150 mm Hg) as inclusion criteria

(Answer D is incorrect).

Answer: B

The landmark ARDSNet trial evaluating lung protective

mechanical ventilation strategies defined low tidal vol-

umes ranging from 4 to 8 mL/kg using predicted body

weight (also known as ideal body weight (Answer B is

correct). Total body weight may overestimate ventilation

requirements in adult patients with obesity because lung

volume is unrelated to increasing total body weight (i.e.,

lung size remains relatively constant irrespective of adult

body mass) (Answers A, C, and D are incorrect).

Answer: B

This patient has both ARDS and septic shock. In addi-

tion, he has likely had ARDS for less than 48 hours;

therefore, the time to initiation of several treatments is

essential. The patient is actively in shock (as evidenced

by his blood pressure), thus making a fluid-conservative

strategy (CVP less than 4 mm Hg) impossible (Answer

C is incorrect). Because the time to presentation is less

than 48 hours and the patient has severe ARDS, he meets

the criteria for cisatracurium administration and prone

positioning, and a treatment plan should include these

two therapies (Answers A and D are incorrect). A ther-

apy plan should include shock resuscitation (fluid-liberal

strategy, CVP 10–14 mm Hg), lung-protective ventilation

(tidal volume 4–8 mL/kg of ideal body weight), prone

positioning, and cisatracurium administration (Answer B

is correct).

Answer: D

The FACTT Lite approach attempts to simplify fluid

management for implementation among ARDS patients

in clinical practice. The parameters used to determine

clinical course of action (remove fluid with diuretic

administration, administer fluid boluses, or monitor with-

out administration of either therapy) include MAP, urine

output, and CVP (pulmonary arterial occlusion pressure

may be optional based on institutional practices for inva-

sive monitoring). Administering fluids in this patient may

not be the most appropriate approach because MAP, CVP,

and urine output do not suggest hypovolemia (Answer C

is incorrect). Although continuous infusion furosemide

may be an option within this published protocol, it is

important to note that both the suggested rate of infu-

sion and the time to re-evaluate are inconsistent with the

FACTT Lite protocol. Re-evaluation should be relatively

short irrespective of the clinical decision-making (i.e.,

1 or 4 hours) (Answer B is incorrect). It is important to

emphasize that the conservative management approaches

defined in this protocol require the patient achieve a

MAP of 60 mm Hg without any vasoactive support for

at least 12 hours. The short time period since vasopressor

support cessation may be too aggressive to adminis-

ter without demonstrating clinical stable hemodynamic

pressures (Answer A is incorrect). The most appropriate

approach would be monitoring until adequate MAP has

been achieved without vasoactive support for at least 12

hours (Answer D is correct).