Intern Report Case Discussion 1.2

intern-report

Presented by Jeff McMenomy, MD

History of Present Illness:
A 75-year-old woman is brought to the Emergency Department by EMS. Her family states the patient complained of gradually worsening generalized weakness and decreased responsiveness over the course of the previous week.  They also state that she is “not being herself”.  EMS noted the patient to be minimally responsive, bradycardic, and hypotensive en route to the hospital.

PMHx: hypertension
PSHx: unknown
FHx: unknown
SocHx: unknown
Allergies: codeine, penicillin
Medications: unknown

Physical Exam

Vitals: T 36.2 C, HR 40, BP 86/43, RR 18, O2 97% on 15 L nonrebreather
Gen: obtunded, oriented x 1, responds to name but not oriented to place or time
HEENT: NC/AT, PERRL, EOMI, no conjunctival pallor, TMs clear b/l, mucous membranes dry, no tonsillar exudates or erythema, + gag reflex
Neck: supple, FROM, no JVD, trachea midline, no cervical LAN
Heart: bradycardic, regular rhythm, no murmurs, rubs, or gallops.
Lungs: clear to auscultation b/l in all fields, no wheezes/rales/rhonchi, normal respiratory effort
Abdomen: soft, nontender, nondistended, bowel sounds normoactive, no rebound/masses/guarding
Vascular: capillary refill 3 seconds, pulses thready but palpable in all four extremities.
Neuro: responds to her name, follows commands. Eyes open spontaneously.  Tongue and uvula are midline.  Moving all four extremities.
Skin: + mild diaphoresis, no rashes

Electrocardiogram:

ecg1

QUESTIONS:

1. Given this patient’s overall clinical picture, what would be the most appropriate initial course of action?

A.   Place patient on a monitor, establish IV access, and administer 0.5 mg doses of atropine while preparing for transcutaneous pacing.

B.   Place patient on a monitor, establish IV access, and administer 325 mg of aspirin, 0.4 mg nitroglycerin sublingual, and morphine at 0.1 mg/kg.

C.   Place patient on a monitor, establish IV access, and administer CPR while preparing a cardiac defibrillator.

D.   Place patient on a monitor, establish IV access, and administer adenosine 6 mg rapid IV push.

E.   Place patient on a monitor, establish IV access, and administer a one liter fluid bolus of normal saline

___
2. Electrical capture by transcutaneous pacing is confirmed by which of the following?

A.   A p-wave, QRS complex, and t-wave showing a first-degree heart block pattern

B.   A pacing spike followed by a p-wave, QRS complex, and t wave all of normal morphology

C.   A return to normal rate with no change in rhythm

D.   A return to normal sinus rhythm with normal rate

E.   A widened QRS after each pacing spike

___

3. Which of the following statements regarding cardiac pacing is true?

A.   Although alternative approaches are acceptable, the femoral vein is the preferred site of percutaneous access for placement of the transvenous pacer.

B.  Hypothermia is a relative contraindication to transvenous pacing.

C.  Second degree heart block type I (Wenckebach)  is among the indications for transvenous pacing.

D.  Transvenous pacing is underutilized in traumatic cardiac arrest and evidence suggests that it may be beneficial in some cases

E.  When compared with the blind insertion technique, ECG-guided transvenous pacer insertion has been shown to be faster.

Discussion

A 75-year-old female presented to the emergency department with hypotention and bradycardia.  ACLS guidelines for symptomatic bradycardia were initiated including IV fluid resuscitation, administration of repeat doses of atropine 0.5mg IVP and placement of transcutaneous pacer.  Her HR remained below 60 bpm with these interventions and therefore transcutaneous pacing was initiated.  Her condition was refractory to transcutaneous pacing as well and so a transvenous pacer was placed.

The right internal jugular was chosen as the site to place the transvenous pacer.  The patient was draped in a sterile fashion and ultrasound guidance was used to obtain percutaneous access of the right internal jugular vein.  After inserting of the transvenous pacing catheter the catheter balloon was inflated and the catheter was floated down the internal jugular vein with ECG-guidance to the superior vena cava, into the right atrium.  Pacing was confirmed by an ECG pattern of an electrical spike followed by a wide QRS complex (see illustration below). After placement of this pacer, the heart was paced at a rate of 60 bpm.  Check out this review article on transcutaneous pacing.

pic

When a patient presents with bradycardia one must first determine if emergent intervention is warranted.  A small percentage of the population has a physiological heart rate of less than 60 bpm.  This patient, in contrast, was having generalized weakness and decreased responsiveness and therefore symptomatic bradycardia.  According to ACLS guidelines, hypotension is one of the “signs or symptoms of poor perfusion caused by the bradycardia.”  Atropine administration, transcutaneous pacing, and later transvenous pacing were all employed to stabilize this patient.  She eventually achieved stability with transcutaneous pacing.

These interventions were administered emergently before any laboratory results had returned.  Laboratory results indicated that electrolyte imbalances and dehydration were contributing factors.  The patient was admitted to the MICU and was eventually discharged after correction of her electrolyte abnormalities and dehydration.

When one is presented with a medical code situation in the emergency department whose conditions fit the criteria for one of the ACLS algorithms, the steps for the appropriate algorithm must be followed emergently.  The underlying cause will often not be apparent at initial presentation to the emergency department.  And once it is discovered it must be addressed.

ANSWERS

1.  The correct answer is A, “Place patient on a monitor, establish IV access, and administer 0.5 mg doses of atropine while preparing for transcutaneous pacing.”  The patient’s ECG shows a junctional bradycardia.  Proper treatment of this patient requires following ACLS guidelines for symptomatic bradycardia.  Current ACLS guidelines for intervention in bradycardia are for patients who have “signs or symptoms of poor perfusion caused by the bradycardia.”  Treatment includes administration of atropine 0.5 mg IV while preparing for transcutaneous pacing.  Atropine may be repeated to a total of 3 mg, otherwise the patient is at risk for anticholinergic toxicity.  Epinephrine and dopamine may also be considered.  If the patient’s condition is refractory to medical management, transcutaneous pacing, followed by  transvenous pacing may be indicated.

(B) is incorrect because it specifies the proper treatment indicated in the ACLS algorithm for acute coronary syndrome, not for symptomatic bradycardia.  Although ACS may be on this patient’s initial list of differential diagnoses, her condition should be treated immediately as symptomatic bradycardia.  If during the course of treatment the patient’s clinical picture begins to exhibit signs or symptoms more specific to ACS, then this patient may need to be treated with aspirin, nitroglycerine, and morphine.

(C) is incorrect because this patient has palpable pulses and CPR is only indicated in patients who are pulseless.  Asynchronous cardioversion is indicated only in pulseless patients and synchronized cardioversion is indicated in certain cases of tachycardia with pulses.  Neither form of cardioversion is indicated in bradycardia.

Administration of adenosine is indicated in the stable patient who is suspected to have a supraventricular tachycardia (AVnRT and AVRT). Answer choice (D), therefore, is incorrect.

Although a fluid bolus is often indicated in hypotension, it is not part of the symptomatic bradycardia treatment algorithm and therefore (E) is incorrect.  This patient’s hypotension may be thought of as a clinical sign of “poor perfusion caused by the bradycardia”  And improving the bradycardia will likely result in an improved blood pressure.  Nonetheless, fluids should be started to augment the patient’s blood pressure.

2.  The correct answer is E, “A widened QRS after each pacing spike.”  Under physiologic conditions, the ventricles of the heart are depolarized rapidly by the rapid progression of an electrical current through the His-Purkinje system, causing the QRS complex to take on a narrow appearance.  When the heart is paced from an external pacing source, such as and artificial pacer, ventricular depolarization takes more time, causing the QRS complex to take on a wide appearance.  The initiation of the electrical impulse by the pacemaker itself can be seen on the ECG as a very narrow spike.

An electrical impulse that begins at the SA node and progresses down all of the heart’s physiological pathways would be required to produce a P-wave, QRS complex, and T-wave of normal morphology, or to produce a pattern consistent with first-degree heart block.  Transcutaneous cardiac pacing does not begin at the SA node and does not progress in this manner.  Answer choices A and B, therefore, are incorrect.

Transcutaneous pacing therapeutically changes the cardiac rate and it also changes the rhythm so that the ECG shows pacing spikes followed by wide QRS complexes when capture is achieved.  Therefore C and D are both incorrect answers.

3.  The correct answer is: B, “Hypothermia is a relative contraindication to transvenous pacing.”  Introducing a transvenous pacer into a patient who is hypothermic has a theoretical potential of causing the patient to have a terminal dysrhythmia.  Hypothermia, therefore, is considered a relative contraindication to transvenous pacing.  Hypothermic patients should be warmed according to standard hypothermic care.

When placing a transcutaneous pacer, either the right internal jugular vein or the left subclavian vein should be considered first as they have been shown to have “the highest rates of proper placement in code situations” (Harrigan et al).  Answer choice A, therefore, is incorrect.  The femoral approach may be indicated in the coagulopathic patient.

Although electronic cardiac pacing may be considered in advanced forms of AV nodal block, second degree heart block type I (Wenckebach) is relatively benign and an invasive procedural is generally not warranted.  Answer choice C, therefore, is incorrect.

Answer choice D is incorrect because cardiac pacing is not indicated in traumatic cardiac arrest.

Although there are advantages to the ECG-guided technique for transvenous pacer insertion, speed is not one of them.  The blind technique is, in fact, faster, making answer choice E incorrect.

References
Harrigan RA, Chan TC, Moonblatt S, Vilke GM, Ufberg JW. Temporary Transvenous pacemaker placement in the emergency department. J Emerg Med 2007;32: 105-11.

This case discussion presented by Jeff McMenomy, MD.

One Response

  1. Strong Work Jazzy.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: