What are 3 pretest probability scoring systems used to evaluate patients with a suspected pulmonary thromboembolism?
Answer
There are 3 validated pretest probability scoring systems that can be used to help clinicians decide who can be sent home, who needs a D-dimer, and who goes straight to CT for suspected PTE.
Wells Criteria
Developed – 1998
Revised – 2000
Simplified – 2001
Geneva Score
Developed – 2001
Revised – 2006
Simplified – 2008
Pulmonary Embolism Rule-Out Criteria (PERC) Score
Developed – 2008
This score is used AFTER the patient is determined to be low-risk using the Well’s or Geneva score. In patients who are low-risk and PERC negative, there is only a 1.6% false-negative rate for missed PTE. Any one of these would deem the patient PERC positive.
Why is this so important?
Although it does help us in deciding who maybe at higher risk of PTE, I personally feel these scoring systems help us document who DOES NOT need work-up. There are quite a few patients who come in with non-specific chest pain or shortness of breath, and you should ALWAYS entertain the idea of PTE in these patients. But, not every single one of these patients need a d-dimer or CTA. Better yet, some of these patients can be discharged home without any investigation if they are low-risk and PERC negative.
Below is an algorithm I modified from Jeff Kline using these clinical decision instruments.
All these images are slides from my talk at the 2015 AAPA Conference
References
Wells PS, Ginsberg JS, Anderson DR. Use of a clinical model for safe management of patients with suspected pulmonary embolism. Annals of Internal Medicine. 1998;129(12):997-1005. [pubmed]
Wells PS, Anderson DR, Rodger M. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer. Thrombosis and Haemostasis. 2000;83(3):416-20. [pubmed]
Wells PS, Anderson DR, Rodger M. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer. Annals of Internal Medicine. 2001;135(2):98-107. [pubmed]
Wicki J, Perneger TV, Junod AF, Bounameaux H, Perrier A. Assessing clinical probability of pulmonary embolism in the emergency ward: a simple score. Archives of Internal Medicine. 2001;161(1):92-7. [pubmed]
Le Gal G, Righini M, Roy PM. Prediction of pulmonary embolism in the emergency department: the revised Geneva score. Annals of Internal Medicine. 2006;144(3):165-71. [pubmed]
Klok FA, Mos IC, Nijkeuter M. Simplification of the revised Geneva score for assessing clinical probability of pulmonary embolism. Archives of Internal Medicine. 2008;168(19):2131-6. [pubmed]
Kline JA, Courtney DM, Kabrhel C. Prospective multicenter evaluation of the pulmonary embolism rule-out criteria. Journal of Thrombosis and Haemostasis. 2008; 6(5):772-80. [pubmed]
This is actually a special episode for the PAINE Podcast as I have the opportunity to do a joint-interview podcast with Chip Lange from TOTAL EM. This was the first time I got to dabble with a conversational-style podcast and I think it went pretty good. Chip and I had a great time doing it and will most definitely be doing more of these in the future.
One of the many saying my Army Airborne Ranger dad has instilled in me growing (and one that I still use today) is the seven “P” approach to accomplishing tasks:
Proper
Planning
and
Preparation
Prevents
Piss
Poor
Performance
What is nice about this saying is that it applies very nicely to the steps of intubation as well.
Prepare
You need to to have everything at the bedside you MIGHT need prior to any intubation attempt. This includes equipment, medications, and any personnel or team members who will assist. If you even suspect this could be a difficult airway, you should have your plan B and plan C options in the room to ward off the evil spirits.
If using video, plug it in and make sure it turns on
Patent IV lines x 2
Suction
Cardiac and pulse oximetry monitor
Bag-valve mask
End-tidal CO2 monitor
Medications
Drawn up and labeled
Concentration read aloud
This also gives you the opportunity to talk with you team about the plan for intubation (how many attempts, progression should plan A, steps of what will happen during the intubation and everyone’s roles during the procedure, etc..), as well as reviewing assisting maneuvers (external laryngeal manipulation, etc.).
Preoxygenate
In order to decrease any deoxygenation-related issues during the intubation attempt, your patient should recieve 100% oxygen at 15 liters per minute through a non-rebreather mask for 3-5 minutes. This will properly de-nitrogenate and super-saturate all the hemoglobin and give you the time you need to visualize and intubate.
Position
“EAR HOLE TO CHEST HOLE”
For ideal visualization, you want to position your patient so that their external auditory meatus lined up to the sternal notch
Premedicate
There are several different medications you can give for premedication purposes to modify the physiologic response during intubation (lidocaine, opiates, atropine, defasculating agents, etc..), but the main one is the sedative. It is generally poor form to paralyze someone before you sedate them. There are several medications you can choose from for sedation in intubation:
Ketamine – 1-2mg/kg IV
My ideal sedative
Etomidate 0.3mg/kg IV
Less hemodynamic compromise
Can cause adrenal suppression
Propofol – 1.5-3mg/kg IV
Can cause hemodynamic instability
Paralyze
There are 2 choices for classes of paralytics:
Depolarizing
Succinylcholine – 1.5-2mg/kg IV
Rapid onset, shortest duration of action
Caution in burn/crush injuries, hyperkalemic patients
Non-Depolarizing
Rocuronium – 1.2mg/kg IV
Vecuronium – 0.3mg/kg IV
Pass The Tube
Once you patient is properly sedative and paralyze, you can proceed to laryngoscopy.
Post-intubation Assessment
Capnography
This is used for confirmation of correct placement of the endotracheal in the trachea and tests for end-tidal CO2. There are 2 main types:
Qualitative
Color change calorimeter
Attaches to end of endotracheal tube and detects CO2 by changes in exhaled pH
GOLD IS GOOD
Quantitative
Continuous Waveform Capnography
Gold standard
Gives you a visual waveform to see if the ventilations are adequate
Securing the Tube
Once you know you are in the right spot and have been confirmed by capnography, you need to secure the tube. There are different ways to achieve and I often defer to the respiratory therapist or nurse on how they want it secured. There are commercial devices that lock the tube in place and secure using velcro straps, all the way to the old standby of adhesive tape. This is a great site that shows several different ways you can secure the endotracheal tube (http://aam.ucsf.edu/article/securing-endotracheal-tube).
Radiography
Chest xray is the gold standard for the radiographical confirmation of endotracheal placement, as well as ensuring the proper depth. The ideal position for the tube depth should be 3-5cm from the carina or at T3-4 position.
Now that the tube is in place, secured, and confirmed, you are done right? WRONG!!! Your patient now has a tube shoved into the tracheal and it is a tad uncomfortable. Postintubation sedation/analgesia is PARAMOUNT for good patient care.
Sedation
Ketamine – 0.1-0.5mg/kg bolus and 0.1-0.5mg/kg/hr infusion
Propofol – 5mcg/kg bolus and 5-50mcg/kg/hr infusion
Midazolam – 0.05mg/kg bolus and 0.025mg/kg/hr infusion
Analgesia
Fentanyl – 2mcg/kg bolus and 1mcg/kg/hr infusion
Hydromorphone – 0.5-1mg/kg bolus and 0.5-3mg/kg/hr infusion
Morphine – 5-10mg/kg bolus and 2-30mg/hr infusion
You should be shooting for a Richmond Agitation Sedation Scale (RASS) of -1 to -3 for adequate sedation following intubation.
Dyspnea is one of the more common complaints that will bring a patient to the ED for evaluation. The most recent data from the CDC shows more than 3.7 million visits to the ED in the United States for shortness of breath alone and more than 11 million for dyspnea-related complaints (cough, chest pain, etc.).
Pathophysiology
There are 3 global processes that have to function in series to prevent a patient from becoming short of breath:
Ventilation
Airflow through the tracheobronchial tree to the terminal alveoli
Ventilation without perfusion = Dead space
Anatomic = trachea, main bronchi
Physiologic = terminal alveoli
Perfusion
Blood flow through the pulmonary arteries to the terminal capillaries
Perfusion without ventilation = Intrapulmonary shunt
Anatomic = right-to-left shunt
Physiologic = terminal alveoli
Gas Exchange
Capillary-alveoli interface to exchange oxygen and carbon dioxide
Determined by arterial-alveoli gradient
5 Main Causes of Hypoxemia
V/Q Mismatch (most common)
PNA, PTE, pulmonary edema, asthma, COPD
Hypoventilation
Drug overdose, neuromuscular disease (GBS, ALS, MG)
Right-to-Left Shunt
Intracardiac
PFO, ASD, VSD
Vascular
PTE, AVM
Alveolar
PNA, atelectasis, pulmonary edema, ARDS
Low Inspired Oxygen
Altitude, fire,
Diffusion Abnormality
COPD, interstitial lung disease
Bedside Evaluation
Vitals
Blood Pressure
Often hypertensive due to stress
Can also be the precipitating factor
Heart Rate
Often tachycardic due to stress and system trying to increase cardiac output for oxygen demand
If bradycardic à think overdose
Respiratory Rate
Will be tachypnic
> 40 bpm is ominous and respiratory failure could be imminent
if bradypnic à think overdose
Temperature
If febrile, then infectious causes go up on differential
Pulse oximetry
Common practice is to give all dyspneic patients oxygen
Lots of research on oxygen in ACS
History
Onset
Severity
Events leading up to this episode
Triggers, compliance with medications
Allergies
Past History
Medical problems, previous episodes
Chest pain
Trauma
Fever
Hemoptysis
Cough
Tobacco history
Medications
Physical Exam
Rapid examination should be performed (often while getting the history) to evaluate for impending respiratory collapse:
Altered mental status
Lethargy to combative
Fatigue of breathing
Audible stridor
Cyanosis
Tripod position
Retractions or accessory muscle use
Fragmented speech
Inability to lie supine
Diaphoresis
Any of the above findings should raise your threshold to intubate.
Once these have been evaluated and ruled-out, you can begin a focused physical exam to address the causes of acute dyspnea:
Petersson J, Glenny RW. Gas exchange and ventilation-perfusion relationships in the lung. The European Respiratory Journal. 2014;44(4):1023-41. [pubmed]
Simon PM, Schwartzstein RM, Weiss JW, Fencl V, Teghtsoonian M, Weinberger SE. Distinguishable types of dyspnea in patients with shortness of breath. The American Review of Respiratory Disease. 1990;142(5):1009-14. [pubmed]
Schneider HG, Lam L, Lokuge A. B-type natriuretic peptide testing, clinical outcomes, and health services use in emergency department patients with dyspnea: a randomized trial. Annals of Internal Medicine. 2099;150(6):365-71. [pubmed]
57-year-old male, with controlled hypertension, presents to emergency department with a 2-hour history of a central, dull, chest pain that does not radiate. He rates it as a 4/10 in severity and denies any aggravating or alleviating factors. He reports some mild nausea and what he reports as “reflux” during this event as well. He denies shortness of breath, vomiting, arm radiation, back radiation, abdominal pain, dizziness, or syncope. His father has HTN, HLP, and had a non-fatal AMI at 62-years-old. He is a never smoker. His BMI is 27.3.
Vital signs show BP-122/82, HR-93, RR-16, O2-100% on room air, and temp-98.0.
Physical exam reveals:
HEENT – NC/AT
Skin – no diaphoresis
Cardiovascular – RRR without M/G/R
Pulmonary – CTA without adventitial breath sounds
Abdomen – S/ND, mild epigastric tenderness to deep palpation
Peripheral Vascular – 2+ pulses throughout
Neuro – A&Ox3, 5/5 strength throughout
EKG is below:
Laboratory Screening:
High-sensitivity troponin (hs-cTnI) – 0.02 ng/dL
CK-MB – 39 U/L
Total CK – 264 U/L
Myoglobin – 22 ng/mL
WHAT WOULD YOU DO NEXT???
Answer:
Discharge home with cardiovascular provocative testing as outpatient.
Why? Low risk HEART score. What is the HEART score? Glad you asked.
The HEART score was first published in 2008 to evaluate occurrence of Major Adverse Cardiac Event (MACE) at 6 weeks. MACE defined in the study was any occurrence of AMI, PCI, CABG, or death. The 5 variables they used are:
R.E.B.E.L EM – A New ED Chest Pain Risk Stratification Score
The HEART score performed better than TIMI and GRACE predicting MACE in acute chest pain patients presenting to the ED.
For our patient, he has a HEART score of 3 (age + history + risk factors). We could have a discussion with him regarding the risk of him having a MACE in the next 6 weeks and the risks/benefits of admission and testing now. Below is a nice patient sheet that the University of Maryland (FEAR THE TURTLE) has developed to help with shared decision making in the ED.
Six AJ, Backus BE, Kelder JC. Chest pain in the emergency room: value of the HEART score. Netherlands Heart Journal. 2008;16(6):191-6. [pubmed]
Backus BE, Six AJ, Kelder JC. A prospective validation of the HEART score for chest pain patients at the emergency department. International Journal of Cardiology. 2013;168(3):2153-8. [pubmed]
So we have interviews all this week for the PA program at UAB and I want to play a little game.
I am curious to see how many applicants follow me on the blog/Twitter/Facebook and rather than flat out ask, I want you to do the following:
Make it a point to come up to me and say “butterscotch“……or tell another faculty member you are interviewing with that you wanted to tell Mr. Maday that “you love Cocoa Puffs, too“.
57-year-old male, with controlled hypertension, presents to emergency department with a 2-hour history of a central, dull, chest pain that does not radiate. He rates it as a 4/10 in severity and denies any aggravating or alleviating factors. He reports some mild nausea and what he reports as “reflux” during this event as well. He denies shortness of breath, vomiting, arm radiation, back radiation, abdominal pain, dizziness, or syncope. His father has HTN, HLP, and had a non-fatal AMI at 62-years-old. He is a never smoker. His BMI is 27.3.
Vital signs show BP-122/82, HR-93, RR-16, O2-100% on room air, and temp-98.0.
Physical exam reveals:
HEENT – NC/AT
Skin – no diaphoresis
Cardiovascular – RRR without M/G/R
Pulmonary – CTA without adventitial breath sounds
Abdomen – S/ND, mild epigastric tenderness to deep palpation
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