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Perioperative cardiac arrest: Causes, Management and Prevention

Cardiac arrest on table is a nightmare for the anesthesiologist and the entire surgical team. Knowledge of the patient, predisposing factors, early detection, aggressive resuscitation and post resuscitation care are the key elements leading to a successful outcome and also safeguard the anesthesiologist against medico legal problems in case of adverse outcome.

● Incidence of perioerative cardiac arrest varies with the definition, facilities available and several other factors.
● Closed claim studies, POCA registry and retrospective audit have been the source of data
● Rare and unusual causes and cases of cardiac arrest still continue to occur
● Role of human factors and organizational structure is also being recognized

Perioperative cardiac arrest is unique in that,

● Many cardiac arrests may be preventable
● Often, immediately recognizeds
● Many patients are previously healthy
● Patient might be receiving oxygen supplementation
● Monitoring is available including capnogram and arterial line
● Vascular access present
● Endotracheal tube can be in place
● Effective resuscitation is more likely, in view of the facilities and expertise available

Predisposing factors

● ASA 3 and more physical risk status
● Compromised / obstructed airway, especially infraglottic obstruction
● Emergency surgery
● Massive blood loss before surgery
● Electrolyte disturbances, especially Hyperkalemia
● Predisposition to malignant hyperthermia
● Morbid obesity
● Obstructive sleep apnoea
● Congestive cardiac failure
● Chronic kidney disease
● Stenotic valvular lesions, aortic stenosis being the most important
● Congenital cardiac defects and arrhythmia (eg various types of congenital QT prolongation syndromes)
● Myopathies
● Persistent hypotension
● Prolonged fasting
● Poor functional status preoperatively

Causes of cardiac arrest on table

● Anaphylaxis
● Bupivacaine induced cardio toxicity
● “ Can’t intubate, Can’t ventilate”
● Sedation induced airway obstruction
● Unrecognized esophageal intubation
● Massive pulmonary aspiration
● Tension pneumothorax
● Massive blood loss
● Hyperkalemia due to massive blood transfusion
● Disseminated intravascular coagulation
● Air embolism, amniotic fluid embolism and Pulmonary embolism
● Massive myocardial infarction
● Iatrogenic causes like wrong drug administration, errors in dosage etc
● Malignant hyperthermia
● High spinal

Pre arrest events

● Hypotension
● Arrhythmia, especially ventricular fibrillation
● Progressive hypoxia

Management

● Confirm cardiac arrest: flat line on ECG (rule out artifacts, disconnection- “flat line protocol”) or non shockable rhythms with pulseless electrical activity, absence of carotid pulse for more than 10 sec and loss of arterial waveform.
● Call for help
● Mask ventilation with 100% oxygen, followed by endotracheal intubation if patient not intubated or when cardiac arrest occurs under regional anaesthesia
● Confirm that endotracheal tube is in place and ventilator is working properly
● Defibrillation, if it’s a shockable rhythm or initiate external cardiac compression
● Internal cardiac compression, if surgically feasible
● Identify and treat the cause : in addition to the 5Ts and 5Hs, consider Hypervagal activity, Hyperthermia, pulmonary Hypertension, Q-T prolongation, auto PEEP etc as causes or contributory factors
● Monitor the progress of resuscitation
● Depending on the cause patient may require transvenous pacing, Defibrillation, adrenaline, Intralipid etc. Important causes of perioperative cardiac arrest and specific management issues are discussed below.

A ACLS- Anesthesia Advanced Circulatory Life Support

Available guidelines for cardiopulmonary resuscitation is not tailor made for the preoperative or anesthesia related cardiac arrests. In general, following are the components of management of anesthesia related cardiac arrest or severe circulatory collapse.
● Early recognition
● 100% oxygen
● High quality CPR which includes effective chest compressions (100-120/min), compression : ventilation ratio of 30:2, early endotracheal intubation, avoidance of hyperventilation, tidal volume of approx 7ml/kg
● Monitoring of ETCO2, arterial waveform and central venous pressure are useful to monitor the progress and outcome of resuscitation. ETCO2 of more than 20 mmHg and relaxation pressure on arterial pressure of more than 40 mmHg are reliable indicators of return of spontaneous circulation.

Determinants of outcome

Better outcome

● Previously healthy patients
● Elective surgery
● Non hypoxemic arrest
● Early recognition, early defibrillation
● Drug induced arrest

Poor outcome

● ASA 3 or more
● Significant co morbid conditions
● Persistent hypotension
● Massive myocardial infarction
● Delayed recognition
● Massive blood loss or severe Hypovolemia
● Severe aortic stenosis

Prevention

● Identify high risk patient
● Plan the anaesthesia techniques and drugs properly
● Investigate the patient appropriately in the preoperative period
● Anticipate and manage aggressively preparers situations : arrhythmia ( severe bradycardia, tachycardia, supraventricular tachycardia, atrial fibrillation, ventricular tachycardia etc)
● Supplemental oxygen administration
● Prevention and management of hypotension
● Appropriate patient blood management
● Precautions against local anesthetic toxicity

Part 2 of the same article will contain details about issues in perioperative cardiac arrest under different specific scenarios

Key articles

1) Cardiac arrest due to anesthesia JAMA 1985, 253: 2373-7
2) Intraoperative Cardiac Arrest in Adults Undergoing Noncardiac Surgery : Incidence, Risk factors and Survival Outcome Anesthesiology 11, 2012, volume 117
3) 13 R C 2 Cardiac Arrest in the Operating Room, lecture by Janusz Andrez, European Society of Anesthesia

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