Using the Perc Rule

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1.Use of the PERC (Pulmonary Embolism Rule-out Criteria) rule can significantly decrease work-up for pulmonary embolism.
To apply this rule, the clinician must first use clinical gestalt to classify the patient as low risk. The PERC rule, which consists of eight clinical criteria including history, physical and vital signs, can then be used. If both of these criteria are met, then there is less than a 2 percent risk that this patient has a PE and no further work-up is needed.

 
Top Headlines in Clinical Emergency Medicine 
 Abstracted from EM:RAP by Chris Feier, MD
 
1.Use of the PERC (Pulmonary Embolism Rule-out Criteria) rule can significantly decrease work-up for pulmonary embolism.
To apply this rule, the clinician must first use clinical gestalt to classify the patient as low risk. The PERC rule, which consists of eight clinical criteria including history, physical and vital signs, can then be used. If both of these criteria are met, then there is less than a 2 percent risk that this patient has a PE and no further work-up is needed.
 
PERC Rule
Age < 50 years
Pulse < 100 bpm
SaO2 > 94%
No unilateral leg swelling
No hemoptysis
No recent trauma or surgery
No prior PE or DVT
No hormone use

2.Norepinephrine is the vasopressor of choice for septic shock.
Studies have shown significant benefits over dopamine including improved splanchnic blood flow, better achievement of hemodynamic goals, and increased likelihood to survive hospital stay if given norepinephrine. Vasopressin as a low dose background agent has also been shown to have beneficial effects when used with a primary vasopressor such as norepinephrine.

3.Bedside Echo can alter management in patients with shock secondary to TCA overdose.
Tricyclic antidepressants block reuptake of norepinephrine thereby causing depressed myocardial contractility and decreased systemic vascular resistance. A quick bedside echo to determine left ventricular function can determine if the patient is in shock from the depressed myocardium or from peripheral vasodilation. In the case of cardiogenic shock, the vasopressor of choice would be dobutamine to increase cardiac contractility and perfusion. On the other hand, if the echo showed grossly normal cardiac function but an empty heart chamber, fluid resuscitation and norepinephrine would be the treatment of choice.

4.The Primary treatment for anaphylaxis is IM Epinephrine.
The therapeutic algorithm for anaphylaxis should begin with epinephrine 0.3-0.5 mg IM, which can be repeated every 5-15 minutes. The intramuscular route has been shown to have better absorption and more rapid peak plasma concentrations than the subcutaneous route and is therefore the route of choice. If the patient is still in extremis, then a diluted solution of epinephrine 0.1mg should be given intravenously. Extreme caution should be used when giving epinephrine intravenously as most adverse effects are from this route.

5.Anaphylactic symptoms may recur up to 72 hours after the initial event.

The disposition of the patient with anaphylaxis that improves after treatment poses a difficult problem to the emergency physician. Anaphylaxis shows a biphasic form in as high as 20% of patients in some series, and has recurred in patients that initially presented to the Emergency Department with stable vital signs. Admission or an Observation Unit would not be an unreasonable disposition for these patients, especially those that exhibited high risk features.

 

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