Slow, big breaths ain’t what the doctor’s ordering

This is part of a recurring series examining landmark articles in Emergency Medicine, in the style of ALiEM’s 52 Articles.

Discussing:  The Acute Respiratory Distress Syndrome Network. “Ventilation with Lower Tidal Volumes as Compared with Traditional Tidal Volumes for Acute Lung Injury and the Acute Respiratory Distress Syndrome” N Eng J Med, May 2000; 342(18): 1301-08

Main Points

This landmark study was stopped early! It determined that in patients with acute respiratory distress syndrome (ARDS) who are treated with lower tidal volumes than those treated with traditional volumes:

  1. Mortality is decreased by 31.0% vs 39.8% (P = 0.007)
  2. Breathing without assistance increases by the 28th day by 65.7% vs 55.0%
  3. The number of ventilator free days increases by 12 ± 11 vs 10 ± 11. days (P = 0.007)

ARDS is a life-threatening condition for which the mortality was quoted in this study to be approximately 40 to 50 percent.  (To be blunt, any study that uses death as its primary outcome is looking at a very ill cohort.) 

Much has been learned about the pathophysiology of ARDS, but very little headway has been made in the treatment of it. The authors of this study looked at adjusting ventilatory tidal volume and plateau pressures for treatment for ARDS.  The authors also measured plasma interleukin-6 in the first 204 of 234 patients as a measure of lung inflammation. The results were significantly in favor of the lower tidal volume group.  

Details

This was a prospective, randomized controlled study that assorted 861 patients into two groups.  Patients were randomly selected to be treated with tradition ventilation treatments, initial tidal volumes of 12 ml per kilogram of predicted body weight and a plateau pressure of 50 cm of water or less, versus lower tidal volumes of 6 ml per kilogram of predicted body weight and a plateau pressure of 30 cm of water or less.

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Think pulmonary embolism and you may find it….

This is part of a recurring series examining landmark articles in Emergency Medicine, in the style of ALiEM’s 52 Articles.

Discussing:  “Prospective Multicenter Evaluation of the Pulmonary Embolism Rule-out Criteria.” (J Thromb Haemost 2008;  Kline JA et al.)

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boringem.org

Main Points

  1. Pulmonary Embolism Rule-out Criteria (PERC):
  • age < 50,
  • heart rate < 100 bpm
  • SaO2 < 95%
  • no hemoptysis
  • no estrogen use
  • no surgery/trauma requiring hospitalization within 4 weeks
  • no unilateral leg swelling
  • no prior venous thromboembolism

2) PERC in combination with clinical gestalt for low suspicion of pulmonary embolism (PE) reduces the probability of venous thromboembolism (VTE) to below 2%.

Background

Chest pain is the most common emergency department chief complaint.  The differential diagnosis is vast, and includes high acuity conditions (such as myocardial infarction, aortic aneurysm, and pulmonary embolism) down to low acuity conditions (such as reflux, muscle strain and anxiety.)  Pulmonary embolism is one of the high risk clinical conditions that should not be missed. However, determining which patient should or should not be worked up for pulmonary embolism can be difficult.   Continue reading

Of course the patient’s blue…that’s why I’m intubating.

 

Discussing: “Preoxygenation, Reoxygenation, and Delayed Sequence Intubation in the Emergency Department” (Weingart SD, J Emerg Med. 2010 Apr 7)

Main Points:

  1. Patients requiring intubation should be classified by oxygenation saturation as low risk, high risk and apneic.  
  2. Reservoir face masks with oxygen set at the highest rate possible are the recommended sources of high FiO2 during preoxygenation.  
  3. All patients, if possible, should be intubated with the head-elevated position to increase safe apnea time.
  4. Consider using CPAP masks, noninvasive positive pressure ventilation or PEEP valves on a bag-valve mask in patients who cannot achieve oxygen saturations greater than 93%-95%
  5. Rocuronium may provide a longer duration of a safe apneic period in patients with a high risk of desaturation.
  6. A nasal cannula set at 15 L/minute is effective at providing oxygenation during the apneic period.

Background:

Intubation is a vital procedure to the Emergency Physician.  Yet there is more to it than just placing an endotracheal tube.  There is the setup, positioning, oxygenation, sedation, checking tube placement, and more.  On top of this, there is the underlying illness to consider.  The truth is, the majority of patients intubated in the Emergency Department (ED) are sick.  Something is very physiologically wrong, and they are not maintaining adequate oxygenation.  It becomes your job to do this for them.  The authors in this article did an extensive literature review on pre-intubation and peri-intubation techniques which reduce the risk of hypoxia in the adult patient requiring intubation in the ED.   Continue reading