at: inbox

Emergency Medicine - Cardiopulmonary Emergencies - Fast Facts | NEJM Resident 360

In this section, we cover the following cardiopulmonary emergencies:

• Cardiac Resuscitation and Advanced Cardiovascular Life Support (ACLS)

• Post–Cardiac Arrest Care

• Therapeutic Hypothermia

• Aortic Dissection

• Pulmonary Embolism

• Syncope

Other topics related to cardiopulmonary emergencies are covered in the following rotation guides:

• Acute Coronary Syndrome (STEMI/NSTEMI), Arrhythmias, Congestive Heart Failure, Myocarditis and Pericarditis, Valvular Diseases, Atrial Fibrillation(Cardiology)

• Asthma, Chronic Obstructive Pulmonary Disease (COPD), Interstitial Lung Disease, Pulmonary Hypertension, Anaphylaxis(Allergy/Immunology)

Cardiac Resuscitation and Advanced Cardiovascular Life Support (ACLS)

The American Heart Association (AHA) offers Basic Life Support (BLS) and Advanced Cardiovascular Life Support (ACLS) training for providers or laypersons who could be involved in a resuscitation. The goal of ACLS is to improve outcomes for adult patients through early recognition and intervention in respiratory arrest, cardiac arrest, and life-threatening arrhythmias. Some related ACLS guidelines and links to algorithms are provided below. These guidelines are regularly updated to reflect new evidence and changes in practice.

High-Yield Summary Points:

• Recognize respiratory arrest, cardiac arrest, and life-threatening arrhythmias.

• Know electrocardiogram (ECG) rhythms:

  • sinus rhythm

  • atrial fibrillation

  • atrial flutter

  • supraventricular tachycardia

  • atrioventricular blocks (first degree, second degree type I, second degree type II, and third degree)

  • asystole

  • pulseless electrical activity

  • ventricular tachycardia (VT)

  • ventricular fibrillation (VF)

• Prioritize rapid, full-depth chest compressions.

• Rapidly defibrillate appropriate rhythms.

• Continuously assess effect of interventions.

Preparation for ACLS

All teams have a leader and positions to ensure organization and efficiency. Closed-loop communication is pivotal to this group effort.

Identifying ACS and Stroke

Identifying acute coronary syndrome (ACS) and stroke is an important part of ACLS given that both conditions are associated with high risk of morbidity and mortality. The HEART Score is used to predict risk of major adverse cardiac events, and the NIH Stroke Scale quantifies stroke severity. (For more on these rules, see the Clinical Rules and Guidance section in this rotation guide).

Life-Threatening Arrhythmias

Become familiar with ECG changes associated with the following arrhythmias. These rhythms are unlikely to maintain adequate perfusion leading to cardiac arrest.

Cardiopulmonary Arrest

Cardiac and pulmonary arrest go hand in hand. For airway management, please see the Common Procedures section in this rotation guide. During resuscitation, reassess reversible causes.

Abbreviations: AED indicates automated external defibrillator; ALS, advanced life support; BLS, basic life support; and CPR, cardiopulmonary resuscitation
(Reprinted with permission 2020 American Heart Association Guidelines for CPR & ECC, Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. 2020 American Heart Association, Inc.)

Post–Cardiac Arrest Care

After return of spontaneous circulation (ROSC), focus on identifying the cause of arrest, preserving neurologic function, and treating complications of resuscitation efforts. The recently resuscitated patient has a proclivity to lose vital signs again.

• Recheck vital signs and ECG; consider bedside ultrasound to evaluate cardiac function, volume status, pulmonary edema, and to rule out pneumothorax or pericardial effusion.

• If the patient is intubated, obtain chest radiograph to ensure endotracheal tube placement and double-check ventilator settings to avoid excessive ventilation, high-tidal volume, or hypocarbia.

• Administer intravenous (IV) fluids, blood, or vasopressors as needed to maintain a mean arterial pressure (MAP) of >65 mmHg. Consider placing central line and arterial line.

• Request cardiology consultation, and consider extracorporeal membrane oxygenation (ECMO) for unstable patients.

• Assess and document neurologic status.

• Consider organ donation early in this population at high risk for mortality. Determine if the patient has an advance directive regarding donation, and marshal resources as appropriate.

(Reprinted with permission 2020 American Heart Association Guidelines for CPR & ECC, Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. 2020 American Heart Association, Inc.)

Therapeutic Hypothermia

Targeted temperature management (TTM; therapeutic hypothermia) is artificially induced hypothermia. TTM is used in patients surviving out-of-hospital sudden cardiac arrest to improve rates of long-term neurologically intact survival. The rationale is that hypothermia reduces oxygen demand and the inflammation cascade.

Indications: The American Heart Assciation (AHA) and the European Resuscitation Council (ERC) recommend that comatose adult patients who experience return of spontaneous circulation (ROSC) after cardiac arrest should be treated with TTM and maintained at a constant temperature between 32°C and 36°C during TTM for at least 24 hours. However, the quality of evidence to support these recommendations is low, and as a result, recommendations may change as new evidence emerges.

Contraindications: There are few recognized contraindications to TTM. The ERC suggests that a higher temperature could be targeted in patients with severe cardiovascular impairment at 33 °C.

Procedure

Patients should be cooled to 32°C–36°C (89.6°F–96.8°F) for at least 24 hours. Cooling should be initiated in the emergency department (ED) with cool IV fluids (30 mL/kg of 4°C NaCl via peripheral IV or femoral central line over 30 minutes) or external cooling devices (such as surface-cooling devices or cold packs).

Phases of Hypothermia

BP indicates blood pressure; K+, serum potassium concentrations;  O₂ sat, oxygen saturation; and SBP, systolic blood pressure.
(Source: Therapeutic Hypothermia after Cardiac Arrest, Circulation 2013.)

Note: Institutions usually have their own policies and procedures for therapeutic hypothermia. Be familiar with yours.

Management Considerations

• shivering: occurs in most patients; should be recognized early and treated aggressively with sedatives and analgesics

• • buspirone and meperidine may lower the shivering threshold; chemical paralysis with sedation is most effective

• bradycardia: the most common arrhythmia; treat only if associated with hypotension

• mechanical ventilation goal: arterial oxygen saturation of 94%–96%

• blood glucose: hypothermia decreases insulin secretion and increases insulin resistance, leading to hyperglycemia, which typically does not require treatment until glucose levels exceed 200 mg/mL; measure it hourly to avoid hypoglycemia, especially with intravenous insulin treatment and during rewarming, when glucose levels can drop quickly

• serum potassium levels: may decrease; serum electrolytes should be measured every 4–6 hours; potassium should be maintained at or above 3.5 mEq/L

Aortic Dissection

Aortic dissection is defined as a tear in the layers of the aorta (usually the intima) and results in the creation of a false lumen. Stanford classification type A involves the ascending aorta and is generally managed with surgery; type B involves the descending aorta and is generally managed medically or with endovascular intervention.

The Stanford Classification of Aortic Dissection

Aortic dissection is a diagnostic challenge due to the broad differential diagnosis of chest pain. Untreated mortality is about 1% per hour during the first 2 days, primarily from Type A dissections. About 40% of patients with type A dissection die before medical evaluation.

Classic History

Aortic dissection most often presents as sudden-onset tearing or ripping sensation to the chest or back. Other presentations include neck or jaw pain, altered mental status, stroke symptoms, and flank pain.

Risk Factors

Risk factors for aortic dissection include the following:

• hypertension

• advanced age

• aortic-valve pathology

• connective tissue disease

• substance abuse

• smoking

• history of tuberculosis

• syphilis

• vasculitis

• third-trimester pregnancy

• blunt trauma

• cardiac surgery

• family history of dissection

Physical Exam

Aortic dissection can be associated with the following symptoms:

• aortic regurgitation

• tamponade

• pulse deficit

• hemodynamic instability

• focal neurologic deficit

Diagnosis

• Labs are not very helpful, but obtain blood type and cross-matching for 6 units if high suspicion; consider D-dimer testing (associated with a high negative predictive value, although ACEP does not recommend its use alone for ruling out aortic dissection).

• ECG is nether sensitive nor specific; acute myocardial infarction with ST elevation can occur if dissection is very proximal and involves one or more coronary arteries.

• Chest radiograph can show a widened aortic knob or mediastinum, pleural effusion, left apical pleural cap, indistinct or irregular aortic contour, or tracheal deviation (these findings are not specific).

• Computed tomography with contrast is highly sensitive and specific.

• Ultrasound is also useful to evaluate pericardial effusion and tamponade.

• The type of dissection is important to know since it will determine management.

Management

• Place on cardiac monitor and obtain IV access.

• To reduce aortic wall stress, the heart rate should be reduced to around 60 beats per minute with the use of IV beta-blockade. This can be followed by IV angiotensin-converting enzyme (ACE) inhibitors or other vasodilators to achieve a target systolic blood pressure <120 mmHg.

• Beta-blockers are first-line medication; if contraindicated, nitrates or calcium-channel blockers can be used.

  • Benzodiazepines are first-line treatment for acute cocaine toxicity–related dissection. Theoretically, unopposed alpha stimulation is a concern if beta-blockers are used.

• Do not send an unstable patient to the scanner!

• Treat pain.

• Consult vascular surgery immediately. Cardiac surgery may be needed if injury is proximal and involves the coronary arteries or aortic valve.

• Type A (involves ascending aorta) is associated with aortic rupture, tamponade, acute myocardial infarction (AMI), aortic regurgitation, hemorrhage, and stroke. Surgical intervention is usually indicated.

• Type B (does not involve ascending aorta) is associated with limb/organ ischemia and is usually treated medically or with endovascular intervention (31%).

Pulmonary Embolism

Occlusion of part of the pulmonary arterial tree can cause acute hypoxemia and cardiac strain. Pulmonary embolism (PE) is a pulmonary artery occlusion caused by a clot that traveled from another part of the body, most often the legs. Other sources include upper-extremity deep vein thrombosis (DVT), indwelling catheter, and right-sided heart chamber thrombus.

Risk Factors

• previous PE/DVT

• hypercoagulable state

• oral contraception use

• cancer

• recent surgery or immobilization

• indwelling vascular catheter

• acute medical illness

Classic Symptoms

• dyspnea (acute or subacute)

• pleuritic chest pain

• palpitations

• cough

• hemoptysis

• lower-extremity pain

• syncope

• severe hemodynamic instability

Clinical Signs

• tachypnea (96%)

• rales (59%)

• tachycardia (45%)

• fever (43%)

• lower-extremity edema (25%)

Workup

Clinical decision rules can guide workup using evidence-based decision making. Wells Criteria for PE probability and Pulmonary Embolism Rule Out Criteria (PERC) can be used to guide your workup. For more on these rules, see Clinical Rules and Guidance in this rotation guidein this rotation guide and Venous Thromboembolism (VTE) and Anticoagulation in the Hematology rotation guide.

Management

Manage PE based on clinical presentation. Current efforts in PE management focus on identifying a stable population eligible for discharge on direct oral anticoagulant (DOAC) therapy or parenteral low-molecular-weight (LMW) heparin compounds versus unstable or potentially unstable patients who would benefit from thrombolytic therapy or embolectomy. For more on PE management see Management of Venous Thromboembolism in the Hematology rotation guide.

Syncope

Syncope is a transient loss of consciousness with an inability to maintain postural tone with self-limited recovery. For a small subset of patients this sign can serve as a life-threatening presage, although most causes of syncope are benign.

Differential Diagnosis

Many conditions can cause syncope, as described in the following table:

Conditions That Can Cause Syncope

Organ System	Conditions
Vasomotor/Vascular	Hemorrhage (GI bleed, ruptured ectopic pregnancy); dehydration/hypovolemia; diabetic neuropathy; diuresis; drug-induced orthostasis (e.g., olanzapine, antihypertensives); dysautonomia/postural hypotension; ectopic pregnancy; hypotension; multisystem atrophy; peripheral polyneuropathy; sepsis; subclavian steal; vasodepressor/vasovagal response; vasomotor insufficiency
Cardiac	Aortic dissection; aortic stenosis; bradyarrhythmia (e.g., sick sinus syndrome, sinoatrial block/atrioventricular block/conduction block, sinus pause >3 seconds); tachyarrhythmia (e.g., ventricular tachycardia, torsades de pointes, paroxysmal supraventricular, tachycardia, Wolff–Parkinson–White syndrome); Brugada syndrome; cardiac myxoma; cardiac outflow obstruction; hypertrophic subaortic stenosis; pacemaker malfunction; primary pulmonary hypertension; prolonged QT syndrome; pulmonary embolism; stress-induced (Takotsubo) cardiomyopathy; subclavian steal; tricuspid stenosis
Situational (vasovagal)	Carotid sinus syncope; cough (post-tussive) syncope; fefecation syncope; micturition syncope; postprandial syncope; swallow syncope
Metabolic/Endocrine	Hypothyroidism; hypoxemia; pheochromocytoma
Central Nervous System	Intracranial hemorrhage (subarachnoid hemorrhage, hemorrhagic stroke); hyperventilation syndrome; hydrocephalus; migraine headache; narcolepsy; panic attacks; seizure disorder; stroke; transient ischemic attack; vertebrobasilar insufficiency; vertebral dissection; drug use

High-Yield History

It is important to elicit the following details of the syncope event:

• triggers

• prodromal symptoms

• duration of loss of consciousness

• present symptomatology

• infection symptoms

• antecedent trauma

• family history of sudden death and risk factors for coagulation problems

• ACS and stroke

Exam

• Orthostatic vital signs are useful for drug-induced and vasomotor causes; they correlate poorly with volume status.

• Listen for murmur.

• Seek neurological abnormality regarding intracranial pathology.

• Consider pulmonary embolus and look for signs of DVT.

• Check for pulse asymmetry, which can suggest dissection.

Workup

• Consider obtaining complete blood count (CBC), basic metabolic panel (BMP), D dimer (if Wells score is high), prothrombin time/international normalized ratio (PT/INR), B-type natriuretic peptide (BNP), troponin, toxicology screen, urine analysis (UA), and pregnancy test in women.

• Look for ECG evidence to suggest an underlying cardiac arrhythmia disorder, which can be subtle (e.g., Wolff–Parkinson–White syndrome, Brugada syndrome, prolonged QT, conduction block, left ventricle [LV] hypertrophy, and arrhythmia).

• Consider cardiac ultrasound to assess valves and appropriate contraction or strain.

• Perform pelvic ultrasound in case of concern for ectopic pregnancy.

• Perform lung ultrasound to evaluate for pulmonary edema.

• Obtain chest radiograph to evaluate for infectious disease, wide mediastinum, or a finding suggestive of PE.

• Obtain CT/MRI of the head to rule out stroke or hemorrhage.

• Patients with syncope can have concomitant trauma and may need additional imaging.

Management and Disposition

• The Boston Syncope Rule and the San Francisco Syncope Rule can help you decide an appropriate disposition for your patient. (For more on these rules, see the Clinical Rules and Guidance section in this rotation guide.)

• Treat suspected etiology. Address airway, breathing, and circulation (ABCs) and emergent situations.

• Young patients with reassuring ECG and physical exam do not need labs and may be discharged home with appropriate return instructions.

• Admit high-risk patients for observation and further syncope workup.

inbox