Question of the Week # 425

425) A 80 day old african american woman with advanced dementia is admitted to the intensive care unit for overwhelming sepsis secondary to a urinary tract infection. At presentation she was hypoxemic and was subsequently, intubated and placed on a ventilator. Blood and urine cultures are obtained and she is started on antibiotics A chest x-ray post-intubation shows endotracheal tube in place and bilateral diffuse alveolar infiltrates. On examination, his pulse is 110/min, Blood pressure is 110/80 mm Hg and respiratory rate is 18/min with the patient on Assist-Control mode on the ventilator. Pulse oximetry reveals 88% on Fio2 90%. Chest examination reveals diffuse crackles. Cardiac examination reveals tachycardia, there is no S3 gallop. Brain natriuretic peptide level is 50 pg/ml . A 2D echocardiogram shows normal left ventricular function with an ejection fraction of 60%. His ventilator settings are as follows : Assist-Control mode; Fio2 ( Fraction of inspired oxygen) : 90%, Respiratory rate : 18/minute, Tidal Volume : 500 ml, PEEP ( Positive End expiatory Pressure) : 5 cm H20 . Arterial blood gas analysis reveals ( on Fio2 70%): pH : 7.36, pCo2 : 45 mmHg, pO2 : 55 mm Hg, Bicarbonate : 23 Meq/L

Which of the following is indicated at this time?

A) Intravenous Furosemide

B) Swan-Ganz Catheter Placement

C) Increase PEEP by 3 cm H20

D) Increase Tidal Volume to 650 ml

E) Increase Fio2 to 100%

18 Responses

  1. C) Increase PEEP by 3 cm H20 -ARDS from sepsis( assuming she does not have CHF from echo, BNP and absence of S3 gallop) If these clues were not there then B) Swan-Ganz Catheter Placement to get PCWP- to make sure she does not have CHF

    • She might still have Diastolic dysfunction with normal EF and no S3 but S4. But BNP is low ruling out CHF- but can u rely on BNP alone?

      • sorry to many buts

      • The picture of sepsis, bilateral cxr infiltrates and po2/fio2 ratio is consistent with ARDS if the infiltrates can not be explained by CHF. A BNP can be elevated in lot of conditions other than CHF – sepsis itself can elevate it therefore, positive predictive value of BNP is low however, it has a very good negative predictive value when it is less than 100 ( A BNP < 100 , 2D echo revealing a good EF excludes CHF as a cause of these b/l infiltrates. Diastolic CHF often is associated with left ventricular hypertrophy and is unlikely to cause such severe infiltrates – even then, BNP would be elevated) . The patient has ARDS and low vT and high PEEP strategy reduces mortality and improves oxygenation. ( In fact , even if this were to be CHF – increasing PEEP is also helpful in CHF along with diuretics) . Swan Ganz catheter insertion has not been shown to reduce mortality in critically ill patients and therefore, it's use has decreased – it is indicated only in cases of complex scenarios where non-invasive clinical methods/ indicators/ tests or procedures have failed to offer any sufficient clues for distinguishing between ARDS vs. CHF

      • I’ve always had this confusion in all the CHF qs , where echo shows LVH , increased EF and presence of S3 gallop. I just assumed u meant eccentric hypertrophy.But it was a lil confusing the first time around.

      • i meant decreased* EF

    • Awesome question!Thank you!

    • C) Increase PEEP by 3 cm H2O. The Patient has ARDS. The best Ventilatory Adjustment to increase her oxygenation are to increase the Fi O2 or increase the PEEP. However FiO2 is not an option because max FiO2 should be set at 60%. It is best to set the mech ventilatory settings of ARDs around 9 H2O. And the tidal vol should be set to the lowest possible value…

  2. C.

  3. awesome!

  4. C


    • Hi Ankit, the patient in the question meets all the criteria for ARDS ( has an underlying cause, bilateral non-chf related CXR infiltrates, pAo2/Fio2 ratio < 200). In ARDS, low VT and High PEEP strategy has been shown to improve oxygenation and reduce mortality. Therefore, the answer is C.
      PEEP will keep the alveoli open at the end of expiration and will keep the alveoli recruited.

      Physiologically "Acute Respiratory Distress Syndrome" has three 'compartments' in the affected lungs: 1) aerated normal lung susceptible to barotrauma induced by inappropriate ventilation 2) air spaces that are filled with exudate and not recruitable 3) areas that are collapsed due to interstitial infiltration and are potentially recruitable. The aim in ARDS is to reduce barotrauma and improve recruitment so as to avoid further damage to lungs and improve oxygenation respectively.

      Recruitment is a ventilation strategy aimed at re-expanding collapsed lung tissue, and then maintaining high PEEP to prevent subsequent 'de-recruitment'. In order to recruit collapsed lung tissue, sufficient pressure must be imposed to exceed the critical opening pressure of the affected lung by strategies such as inverse ratio Pressure controlled ventilation etc . Once the alveoli are opened, high PEEP is applied to prevent them from collapsing again

  6. C-


  8. Good explanation —many thanks.

  9. thank you a lot…

  10. C- increase PEEP➡️➡️ ⬆️ pO2➡️➡️ Oxygen saturation

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