Cardiopulmonary Arrest in Adults

Etiology

There are various causes for cardiopulmonary arrest in adults which varies by age and population. However, patients diagnosed with cardiac disease are more susceptible to having a cardiac arrest. Furthermore, it can be classified into different categories, which include cardiac, respiratory, and traumatic causes. But 75% of cardiac arrest incidents are believed to be due to coronary artery diseases.[2]

Cardiac Causes

Coronary Artery Disease

Coronary artery abnormalities:

• Anomalous coronary artery anatomy.
• Acute lesions (platelet aggregation, plaque fissuring, acute thrombosis).
• Chronic atherosclerosis.
• coronary artery spasm

Myocardial Infarction: 

• Acute
• Healed

Myocardial Hypertrophy

• Secondary
• Hypertrophic cardiomyopathy
  • Nonobstructive
  • Obstructive

Valvular Heart Disease

Infiltrative and Inflammatory Disorders

• Infiltrative diseases
• Noninfectious inflammatory diseases
• Myocarditis

Dilated Cardiomyopathy

Electrophysiologic Abnormalities

Inherited Disorders

• Early repolarization syndrome.  
• Brugada syndrome  
• Short QT syndrome.
• Long QT syndrome.
• Catecholaminergic polymorphic ventricular tachycardia

Heart Failure

• Ejection fraction less than 35%[3]

Congenital disease 

•       Tetralogy of Fallot

Respiratory Causes

• Airway obstruction: 
• Bronchospasm due to (pulmonary edema, pulmonary hemorrhage, and pneumonia)
• Severe asthma or Chronic Obstructive Pulmonary Disease (COPD).
• Pulmonary Embolism
• Respiratory Muscle Weakness: due to spinal cord injury.

Traumatic Causes

Overall, the prevalence of cardiac causes is around 50% to 60%. Whilst, the second most common cause that is respiratory insufficiency is around 15% to 40%.[4]

Epidemiology

Cardiac arrest is divided into out-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA). However, the incidence of cardiopulmonary arrest worldwide is not well described. In the U.S, more than 290,000 IHCA occur in adults annually, whilst 326,000 cases of OHCA among adults occur yearly. Half of these are unwitnessed.[4][5] 

Men and women in middle-age have different susceptibilities to cardiopulmonary arrest; however, the sex differences decrease with increasing age. The difference in risk for cardiopulmonary arrest collateral the variations in age-related risks for other features of coronary heart disease (CHD) between males and females. As the gender gap for signs of coronary heart disease closes in the 6th to 8th decades, the excess risk of arrest in males progressively narrows. In spite of the lower incidence among younger women, CHD risk factors such as diabetes (DM), cigarette smoking, hyperlipidemia, and hypertension (HTN) are very highly influential.

Pathophysiology

Data from postmortem examinations of cardiopulmonary arrest and sudden cardiac death (SCD) victims correlate with the clinical observations on the prevalence of coronary artery disease as the major structural etiologic factor. Higher than 80% of victims have pathologic findings of coronary artery disease. The pathologic description often involves a combination of extensive atherosclerosis of the coronary arteries along with unstable coronary artery lesions, which include various permutations of fissured, eroded, or ruptured plaques; and/or thrombosis. As many as seventy percent of men who die suddenly have preexisting healed myocardial infarctions, whereas only twenty percent have recent acute MIs, in spite of the prevalence of thrombi and unstable plaques.[6]

History and Physical

In numerous patients, warning signs and symptoms may precede a cardiac arrest. Nevertheless, these features are ignored and unrecognized several times because those who survive after experiencing cardiopulmonary arrest, many of them suffer from amnesia while those patients who suffered cardiopulmonary arrest but survived and remember the event reveals that the most common sign was palpitations, shortness of breath, nausea, and chest pain. 

Clinicians examing cardiopulmonary arrest should start head-to-toe assessment immediately which will help to formulate the plan of management. The physical examination will help to diagnose the cardiopulmonary arrest as well as provide the most important information regarding the possible cause and the prognosis. While, the history will help to delineate at what time the event took place, what the victim was doing, and the involvement of drugs. In many cases, the gold standard for diagnosing the cardiopulmonary arrest is the loss of carotid pulse, But, many studies have shown that the rescuers often make a mistake while checking the carotid pulse, whether they are laypersons or the healthcare professionals.[7]

Evaluation

Cardiopulmonary resuscitation should not be interrupted for doing blood or radiological investigation. However, point of care testing, like blood glucose or serum potassium may be done if it doesn't interfere with cardiopulmonary resuscitation efforts. Point of care ultrasound can also be used to evaluate the activity of the heart during cardiopulmonary resuscitation which has proved beneficial in many studies.[8]

Treatment / Management

Five stages in the management of the patient with confirmed cardiopulmonary arrest are: 

1.  Initial evaluation plus Basic Life Support
2.  Defibrillation
3.  Advanced Life Support
4.  Post-resuscitation care
5.  Long-term management

Once the diagnosis of cardiopulmonary arrest is confirmed, then basic life support (BLS) and defibrillation can be carried out by the public, physicians, paramedical personnel, trained laypersons, and nurses. There is an increasing demand for specialized skills such as Advanced Life Support (ALS), post-resuscitation care, and long-term management of post cardiopulmonary arrest patients. The cardiopulmonary arrest could be reversed by two main interventions, i.e., early CPR and early Automated external defibrillation (AED). The first step involves recognition of the cardiopulmonary arrest and the BLS measures. If defibrillation is available for public use, then it should be activated and used if needed. Next, advanced life support (ALS) measures are used, involving IV/IO medication administration. If spontaneous circulation returns, then the case will undergo post-resuscitation care along with subsequent long-term management. The identification of a cardiopulmonary arrest victim includes ensuring that the patient is unresponsive, pulseless, and having abnormal breathing. Once the patient is identified, immediate CPR and activation of the Emergency Medical Services (EMS) should be done promptly. Nowadays, public access to defibrillation has been adding another layer of response.

Initial Evaluation and BLS

Confirming cardiopulmonary arrest need careful examination of the patient's level of consciousness, skin color, breathing movement, and arterial pulse either in the carotid or femoral artery. Just after confirming the arrest, the immediate responsibility of the rescuer is to call Emergency Medical Services and start CPR.

It is essential to diagnose the signs of aspirations of a foreign body in the respiratory tract, which includes severe stridor, dyspnea, suprasternal and intercostal retractions. It is recommended to do the Heimlich maneuver if we are suspecting aspiration.

Maintaining a patent airway is necessary for successful cardiopulmonary resuscitation. Maneuvers like chin lift, head tilt, and jaw thrust can be used to keep the airway patent. Any visible foreign bodies like displaced dentures should be removed from the oropharynx. Ventilatory aids like oropharyngeal airway (OPA) and the nasopharyngeal airway (NPA) may be used if the rescuer is experiencing difficulty in ventilating the patient.[9][10](B2)

The AHA guideline suggested certain recommendation for doing high-quality CPR:[11] (B2)

1. Compression should start within 10 seconds of diagnosing cardiopulmonary arrest.
2. Two breaths to be given after 30 compressions. Excessive ventilation should be avoided.
3. Every effort should be made to reduce the interruption while changing the rescuer or while checking the rhythm.
4. The rate of compression should be between 100 to 120 per minute
5. The depth of compression should be between 2 to 2.4 inches for adults.
6. Adequate time should be given for chest recoil

Automated External Defibrillation

The AEDs are easily handled via nonconventional responders, for instance: ambulance drivers, police officers, firefighters, security guards, and laypersons. Recent studies have suggested that AED use via nonconventional responders could improve the survival rates of cardiopulmonary arrest as the arrival of the ALS team takes time, and early defibrillation by non-conventional responders will not only reduce the time for defibrillation but will also improve patient outcome.

Advanced Cardiac Life Support

Providers can use basic life support along with advanced airway aid and medication like epinephrine and amiodarone for CPR. The advanced airway may include supraglottic airway devices and endotracheal tubes. ACLS team has the further advantage of cardiac rhythm interpretation and using defibrillation when indicated.

ADVANCED CARDIAC LIFE SUPPORT (ACLS) is designed to deliver adequate ventilation, stabilize the blood pressure along with the cardiac output, control cardiac arrhythmias, and restore organ perfusion. Maneuvers needed to accomplish these goals include-

1.  Defibrillation and pacing.
2.  Endotracheal tube intubation and mechanical ventilation
3.  Intravenous line insertion.

The rapidity by which defibrillation is performed is an essential element for improving patient outcomes. The AHA guideline suggested certain recommendation for defibrillation-

1. Cardiopulmonary resuscitation should be carried out whilst the AED is being charged
2. Immediate early defibrillation should be given preference over intubation and intravenous line insertion
3. A defibrillator with a biphasic waveform is preferred over monophasic.
4. Manufacturers recommended energy dose should be used for the first shock. If this is not mentioned, then the maximum dose should be used for defibrillation.
5. Fixed versus escalating energy for subsequent shock should depend on manufacturers' recommendations. If the machine has the capability to escalate the energy, then higher energy should be used for a subsequent shock.
6. A single shock strategy should be preferred to stacked shock.

After failed defibrillation, epinephrine, 1mg I/V, should be given. Furthermore, the dose of this drug may be repeated after periods of three to five minutes. Additionally, vasopressin has been recommended as an alternative.[12]

After 2 or 3 failed attempts, immediate intubation and arterial blood gas analysis should be carried out. Those patients who still remain acidotic even after intubation and successful defibrillation should be given 1 new/ kg of NaHCO3 initially, and further 50 percent of the dose may be repeated after 10 minutes.

Antiarrhythmic therapy with amiodarone may be started after recurrent electrical instability and failed defibrillation. 150 mg amiodarone should be given over 10 minutes, followed by 1 mg/ hr for 6 hours and 0.5 mg/ hour for the next 18 hours. Procainamide is rarely used nowadays. Calcium gluconate is not considered safe, and its use is only reserved for patients having hyperkalemia or have taken a lethal dose of calcium channel blocker.[13]

Postresucitation Care

This phase starts with the successful return of spontaneous circulation. Generally, the Primary ventricular fibrillation after acute myocardial infarction( AMI)  are highly responsive to treatment and are readily controlled while in secondary ventricular fibrillation after AMI, resuscitative efforts are usually less successful, and those patients who are resuscitated successfully, the rate of recurrence of VF is very high. Patient outcome is determined by hemodynamic stability. Asystole, bradyarrhythmias, and PEA are commonly seen in hemodynamically unstable patients.[14]

The outcomes and the clinical picture after In-hospital cardiopulmonary arrest (IHCA) associated with the noncardiac diseases are very poor, and in some successfully resuscitated cases, the post-resuscitation course is controlled by the nature of the underlying illness. Patients with cancer, central nervous system disease, renal failure have a survival rate of less than ten percent after IHCA.

Long-Term Management After The Survival Of OHCA

Patients who survive cardiopulmonary arrest without irreversible damage to the brain must undergo proper investigation in order to know the etiology and definite intervention so that such episodes can be prevented in the future.

Patients with cardiopulmonary arrest due to myocardial ischemia should be managed by surgical, pharmacological ( anti ischemia therapy), and radiological intervention so that long term survival can be improved.

Survivors of cardiopulmonary arrest due to diseases, like hypertrophic cardiomyopathies, rare inherited disorders, right ventricular dysplasia, catecholaminergic polymorphic VT, Brugada syndrome, and long QT syndrome, are the candidates for Implantable cardioverter-defibrillator (ICD).

Differential Diagnosis

Patients with cardiopulmonary arrest will be pulseless and unresponsive. But there are certain conditions having clinical manifestations similar to cardiopulmonary arrest. It includes syncope, seizure, and overdose of certain medications like opioids.[1] We should try to recognize and treat reversible causes of cardiopulmonary arrest commonly referred to as Hs and Ts. It includes-

• Hypovolemia
• Hypoxia
• Hypothermia
• Hypo/hyperkalemia
• Acidosis
• Tension pneumothorax
• Toxic overdose of drugs
• Thromboembolism/pulmonary embolism
• Thrombus/acute myocardial infarction
• Cardiac tamponade

Prognosis

Witnessed cardiopulmonary arrest along with immediate CPR and defibrillation have better patient survival and outcome.[15] Healthy and young patients are more likely to obtain the return of spontaneous circulation as compared to elderly patients with known co-morbidities such as IHD.

Complications

Various complications can occur during cardiopulmonary resuscitation. AED failure is the most common complication. Other complications include the inability to obtain venous access, rib fracture, pneumothorax, pneumomediastinum, hemothorax, lung laceration, pulmonary hemorrhage, injury to the major vessel, and cardiac tamponade.