This patient is displaying symptoms consistent with a diagnosis of an acute myocardial infarction. It is important to provide pain relief as soon as possible. One option for pain relief is GTN, which can be taken sublingually or buccally. However, if there is suspicion of an acute myocardial infarction, it is recommended to offer intravenous opioids such as morphine.

Aspirin should be offered to all patients with unstable angina or NSTEMI as soon as possible and should be continued indefinitely, unless there are contraindications such as a bleeding risk or aspirin hypersensitivity. A loading dose of 300 mg should be administered promptly after presentation.

For patients without a high bleeding risk who do not have coronary angiography planned within 24 hours of admission, fondaparinux should be administered. However, for patients who are likely to undergo coronary angiography within 24 hours, unfractionated heparin can be offered as an alternative to fondaparinux. In cases of significant renal impairment (creatinine above 265 micromoles per litre), unfractionated heparin with dose adjustment guided by clotting function monitoring can also be considered as an alternative to fondaparinux.

Routine administration of oxygen is no longer recommended, but it is important to monitor oxygen saturation using pulse oximetry as soon as possible, preferably before hospital admission. Supplemental oxygen should only be offered to individuals with an oxygen saturation (SpO2) of less than 94% who are not at risk of hypercapnic respiratory failure, with a target SpO2 range of 94-98%. For individuals with chronic obstructive pulmonary disease who are at risk of hypercapnic respiratory failure, a target SpO2 range of 88-92% should be aimed for until blood gas analysis is available.

Bivalirudin, a specific and reversible direct thrombin inhibitor (DTI), is recommended by NICE as a possible treatment for adults with STEMI who are undergoing percutaneous coronary intervention.

For more information, please refer to the NICE guidelines on the assessment and diagnosis of chest pain of recent onset.

A summary of the vessels involved in different types of myocardial infarction, along with the corresponding ECG leads and the location of the infarction.

For instance, an anteroseptal infarction involving the left anterior descending artery is indicated by ECG leads V1-V3. Similarly, an anterior infarction involving the left anterior descending artery is indicated by leads V3-V4.

In cases of anterolateral infarctions, both the left anterior descending artery and the left circumflex artery are involved, and this is reflected in ECG leads V5-V6. An extensive anterior infarction involving the left anterior descending artery is indicated by leads V1-V6.

Lateral infarcts involving the left circumflex artery are indicated by leads I, II, aVL, and V6. Inferior infarctions, on the other hand, involve either the right coronary artery (in 80% of cases) or the left circumflex artery (in 20% of cases), and this is shown by leads II, III, and aVF.

In the case of a right ventricular infarction, the right coronary artery is involved, and this is indicated by leads V1 and V4R. Lastly, a posterior infarction involving the right coronary artery is shown by leads V7-V9.

The septum, which is a part of the heart, can be best identified by examining leads V1 and V2. The septum receives its blood supply from the proximal left anterior descending artery (LAD). The LAD is responsible for supplying blood to the anterior myocardium and also contributes to the blood supply of the lateral myocardium. If the LAD becomes blocked, it can result in ST elevation in all the chest leads.

Further Reading:

Acute Coronary Syndromes (ACS) is a term used to describe a group of conditions that involve the sudden reduction or blockage of blood flow to the heart. This can lead to a heart attack or unstable angina. ACS includes ST segment elevation myocardial infarction (STEMI), non-ST segment elevation myocardial infarction (NSTEMI), and unstable angina (UA).

The development of ACS is usually seen in patients who already have underlying coronary heart disease. This disease is characterized by the buildup of fatty plaques in the walls of the coronary arteries, which can gradually narrow the arteries and reduce blood flow to the heart. This can cause chest pain, known as angina, during physical exertion. In some cases, the fatty plaques can rupture, leading to a complete blockage of the artery and a heart attack.

There are both non modifiable and modifiable risk factors for ACS. non modifiable risk factors include increasing age, male gender, and family history. Modifiable risk factors include smoking, diabetes mellitus, hypertension, hypercholesterolemia, and obesity.

The symptoms of ACS typically include chest pain, which is often described as a heavy or constricting sensation in the central or left side of the chest. The pain may also radiate to the jaw or left arm. Other symptoms can include shortness of breath, sweating, and nausea/vomiting. However, it’s important to note that some patients, especially diabetics or the elderly, may not experience chest pain.

The diagnosis of ACS is typically made based on the patient’s history, electrocardiogram (ECG), and blood tests for cardiac enzymes, specifically troponin. The ECG can show changes consistent with a heart attack, such as ST segment elevation or depression, T wave inversion, or the presence of a new left bundle branch block. Elevated troponin levels confirm the diagnosis of a heart attack.

The management of ACS depends on the specific condition and the patient’s risk factors. For STEMI, immediate coronary reperfusion therapy, either through primary percutaneous coronary intervention (PCI) or fibrinolysis, is recommended. In addition to aspirin, a second antiplatelet agent is usually given. For NSTEMI or unstable angina, the treatment approach may involve reperfusion therapy or medical management, depending on the patient’s risk of future cardiovascular events.

Aortic stenosis is a common condition where the valve in the heart becomes narrowed due to the progressive calcification that occurs with age. This typically occurs around the age of 70. Other causes of aortic stenosis include calcification of a congenital bicuspid aortic valve and rheumatic fever.

The symptoms of aortic stenosis can vary but commonly include difficulty breathing during physical activity, fainting, dizziness, chest pain (angina), and in severe cases, sudden death. However, it is also possible for aortic stenosis to be asymptomatic, meaning that there are no noticeable symptoms.

When examining a patient with aortic stenosis, there are several signs that may be present. These include a slow-rising and low-volume pulse, a narrow pulse pressure, a sustained apex beat, a thrill (a vibrating sensation) in the area of the aorta, and an ejection click if the valve is pliable. Additionally, there is typically an ejection systolic murmur, which is a specific type of heart murmur, that can be heard loudest in the aortic area (located at the right sternal edge, 2nd intercostal space) and may radiate to the carotid arteries.

It is important to differentiate aortic stenosis from aortic sclerosis, which is a degeneration of the aortic valve but does not cause obstruction of the left ventricular outflow tract. Aortic sclerosis can be distinguished by the presence of a normal pulse character and the absence of radiation of the murmur.

Acute aortic dissection is characterized by the rapid formation of a false, blood-filled channel within the middle layer of the aorta. It is estimated to occur in 3 out of every 100,000 individuals per year.

Patients with aortic dissection typically experience intense chest pain that spreads to the area between the shoulder blades. The pain is often described as tearing or ripping and may also extend to the neck. Sweating, paleness, and rapid heartbeat are commonly observed at the time of presentation. Other possible symptoms include focal neurological deficits, weak pulses, fainting, and reduced blood flow to organs.

A significant difference in blood pressure between the arms, greater than 20 mmHg, is a highly sensitive indicator. If the dissection extends backward, it can involve the aortic valve, leading to the early diastolic murmur of aortic regurgitation.

Risk factors for aortic dissection include hypertension, atherosclerosis, aortic coarctation, the use of sympathomimetic drugs like cocaine, Marfan syndrome, Ehlers-Danlos syndrome, Turner’s syndrome, tertiary syphilis, and pre-existing aortic aneurysm.

Aortic dissection can be classified according to the Stanford classification system:
– Type A affects the ascending aorta and the arch, accounting for 60% of cases. These cases are typically managed surgically and may result in the blockage of coronary arteries and aortic regurgitation.
– Type B begins distal to the left subclavian artery and accounts for approximately 40% of cases. These cases are usually managed with medication to control blood pressure.

This patient is likely experiencing an acute coronary syndrome, possibly a non-ST-elevation myocardial infarction (NSTEMI) or unstable angina. The troponin test will help confirm the diagnosis. The patient’s ECG showed ST depression in the inferior leads, but this normalized after treatment with GTN and morphine, ruling out a ST-elevation myocardial infarction (STEMI).

Immediate pain relief should be provided. GTN (sublingual or buccal) can be used, but intravenous opioids like morphine should be considered, especially if a heart attack is suspected.

Aspirin should be given to all patients with unstable angina or NSTEMI as soon as possible and continued indefinitely, unless there are contraindications like bleeding risk or aspirin hypersensitivity. A loading dose of 300 mg should be administered right after presentation.

Fondaparinux should be given to patients without a high bleeding risk, unless coronary angiography is planned within 24 hours of admission. Unfractionated heparin can be an alternative to fondaparinux for patients who will undergo coronary angiography within 24 hours. For patients with significant renal impairment, unfractionated heparin can also be considered, with dose adjustment based on clotting function monitoring.

Routine administration of oxygen is no longer recommended, but oxygen saturation should be monitored using pulse oximetry as soon as possible, preferably before hospital admission. Supplemental oxygen should only be offered to individuals with oxygen saturation (SpO2) below 94% who are not at risk of hypercapnic respiratory failure, aiming for a SpO2 of 94-98%. For individuals with chronic obstructive pulmonary disease at risk of hypercapnic respiratory failure, a target SpO2 of 88-92% should be achieved until blood gas analysis is available.

Bivalirudin, a specific and reversible direct thrombin inhibitor (DTI), is recommended by NICE as a possible treatment for adults with STEMI undergoing percutaneous coronary intervention.

For more information, refer to the NICE guidelines on the assessment and diagnosis of chest pain of recent onset.

Aortic dissection is a condition that occurs when the middle layer of the aorta, known as the tunica media, becomes weakened. This weakening leads to the development of cases of aortic dissection.

Further Reading:

Aortic dissection is a life-threatening condition in which blood flows through a tear in the innermost layer of the aorta, creating a false lumen. Prompt treatment is necessary as the mortality rate increases by 1-2% per hour. There are different classifications of aortic dissection, with the majority of cases being proximal. Risk factors for aortic dissection include hypertension, atherosclerosis, connective tissue disorders, family history, and certain medical procedures.

The presentation of aortic dissection typically includes sudden onset sharp chest pain, often described as tearing or ripping. Back pain and abdominal pain are also common, and the pain may radiate to the neck and arms. The clinical picture can vary depending on which aortic branches are affected, and complications such as organ ischemia, limb ischemia, stroke, myocardial infarction, and cardiac tamponade may occur. Common signs and symptoms include a blood pressure differential between limbs, pulse deficit, and a diastolic murmur.

Various investigations can be done to diagnose aortic dissection, including ECG, CXR, and CT with arterial contrast enhancement (CTA). CT is the investigation of choice due to its accuracy in diagnosis and classification. Other imaging techniques such as transoesophageal echocardiography (TOE), magnetic resonance imaging/angiography (MRI/MRA), and digital subtraction angiography (DSA) are less commonly used.

Management of aortic dissection involves pain relief, resuscitation measures, blood pressure control, and referral to a vascular or cardiothoracic team. Opioid analgesia should be given for pain relief, and resuscitation measures such as high flow oxygen and large bore IV access should be performed. Blood pressure control is crucial, and medications such as labetalol may be used to reduce systolic blood pressure. Hypotension carries a poor prognosis and may require careful fluid resuscitation. Treatment options depend on the type of dissection, with type A dissections typically requiring urgent surgery and type B dissections managed by thoracic endovascular aortic repair (TEVAR) and blood pressure control optimization.

Amiodarone is a medication that is recommended to be administered after the third shock in a shockable cardiac arrest (Vf/pVT) while chest compressions are being performed. The prescribed dose is 300 mg, given as an intravenous bolus that is diluted in 5% dextrose to a volume of 20 mL. It is important to note that amiodarone is not suitable for treating PEA or asystole.

In cases where VF/pVT persists after five defibrillation attempts, an additional dose of 150 mg of amiodarone should be given. However, if amiodarone is not available, lidocaine can be used as an alternative. The recommended dose of lidocaine is 1 mg/kg. It is crucial to avoid administering lidocaine if amiodarone has already been given.

Amiodarone is classified as a membrane-stabilizing antiarrhythmic drug. It works by prolonging the duration of the action potential and the refractory period in both the atrial and ventricular myocardium. This medication also slows down atrioventricular conduction and has a similar effect on accessory pathways.

Additionally, amiodarone has a mild negative inotropic action, meaning it weakens the force of heart contractions. It also causes peripheral vasodilation through non-competitive alpha-blocking effects.

It is important to note that while there is no evidence of long-term benefits from using amiodarone, it may improve short-term survival rates, which justifies its continued use.

Dressler’s syndrome is a form of pericarditis that occurs within 2 to 10 weeks following a heart attack or cardiac surgery. It is distinguished by intense chest pain that is usually alleviated by assuming an upright position. Additionally, individuals may experience a mild fever, a pericardial rub, pulsus paradoxus, and indications of right ventricular failure.

The second heart sound (S2) is created by vibrations produced when the aortic and pulmonary valves close. It marks the end of systole. It is normal to hear a split in the sound during inspiration.

A loud S2 can be associated with certain conditions such as systemic hypertension (resulting in a loud A2), pulmonary hypertension (resulting in a loud P2), hyperdynamic states (like tachycardia, fever, or thyrotoxicosis), and atrial septal defect (which causes a loud P2).

On the other hand, a soft S2 can be linked to decreased aortic diastolic pressure (as seen in aortic regurgitation), poorly mobile cusps (such as calcification of the aortic valve), aortic root dilatation, and pulmonary stenosis (which causes a soft P2).

A widely split S2 can occur during deep inspiration, right bundle branch block, prolonged right ventricular systole (seen in conditions like pulmonary stenosis or pulmonary embolism), and severe mitral regurgitation. However, in the case of atrial septal defect, the splitting is fixed and does not vary with respiration.

Reversed splitting of S2, where P2 occurs before A2 (paradoxical splitting), can occur during deep expiration, left bundle branch block, prolonged left ventricular systole (as seen in hypertrophic cardiomyopathy), severe aortic stenosis, and right ventricular pacing.

The timing of the initial rise, peak, and return to normality of various cardiac enzymes can serve as a helpful guide. Creatine kinase, the main cardiac isoenzyme, typically experiences an initial rise within 4-8 hours, reaches its peak at 18 hours, and returns to normal within 2-3 days. Myoglobin, which lacks specificity due to its association with skeletal muscle damage, shows an initial rise within 1-4 hours, peaks at 6-7 hours, and returns to normal within 24 hours. Troponin I, known for its sensitivity and specificity, exhibits an initial rise within 3-12 hours, reaches its peak at 24 hours, and returns to normal within 3-10 days. HFABP, or heart fatty acid binding protein, experiences an initial rise within 1.5 hours, peaks at 5-10 hours, and returns to normal within 24 hours. Lastly, LDH, predominantly found in cardiac muscle, shows an initial rise at 10 hours, peaks at 24-48 hours, and returns to normal within 14 days.

Indications for drug treatment or pacing in patients with bradycardia include shock, syncope, myocardial ischemia, heart failure, and the presence of risk factors for asystole. If any of these adverse features are present, it is important to consider drug treatment or pacing. However, even if none of these adverse features are present, patients may still require drug treatment or pacing if they have risk factors for developing asystole, such as recent asystole, Mobitz II AV block, complete heart block with broad QRS, or a ventricular pause longer than 3 seconds.

Further Reading:

Causes of Bradycardia:
– Physiological: Athletes, sleeping
– Cardiac conduction dysfunction: Atrioventricular block, sinus node disease
– Vasovagal & autonomic mediated: Vasovagal episodes, carotid sinus hypersensitivity
– Hypothermia
– Metabolic & electrolyte disturbances: Hypothyroidism, hyperkalaemia, hypermagnesemia
– Drugs: Beta-blockers, calcium channel blockers, digoxin, amiodarone
– Head injury: Cushing’s response
– Infections: Endocarditis
– Other: Sarcoidosis, amyloidosis

Presenting symptoms of Bradycardia:
– Presyncope (dizziness, lightheadedness)
– Syncope
– Breathlessness
– Weakness
– Chest pain
– Nausea

Management of Bradycardia:
– Assess and monitor for adverse features (shock, syncope, myocardial ischaemia, heart failure)
– Treat reversible causes of bradycardia
– Pharmacological treatment: Atropine is first-line, adrenaline and isoprenaline are second-line
– Transcutaneous pacing if atropine is ineffective
– Other drugs that may be used: Aminophylline, dopamine, glucagon, glycopyrrolate

Bradycardia Algorithm:
– Follow the algorithm for management of bradycardia, which includes assessing and monitoring for adverse features, treating reversible causes, and using appropriate medications or pacing as needed.
https://acls-algorithms.com/wp-content/uploads/2020/12/Website-Bradycardia-Algorithm-Diagram.pdf

This patient has developed a non-ST elevation myocardial infarction (NSTEMI). The electrocardiogram (ECG) reveals widespread ST depression, indicating widespread subendocardial ischemia. Additionally, the troponin test results are positive, indicating myocyte necrosis.

The acute coronary syndromes consist of unstable angina, non-ST elevation myocardial infarction (NSTEMI), and ST-elevation myocardial infarction (STEMI).

Unstable angina is characterized by one or more of the following: angina of effort occurring over a few days with increasing frequency, angina episodes occurring recurrently and predictably without specific provocation, or an unprovoked and prolonged episode of cardiac chest pain. The ECG may show T-wave/ST-segment changes, similar to this case. Cardiac enzymes are typically normal, and the troponin test is negative in unstable angina.

Non-ST elevation myocardial infarction (NSTEMI) typically presents with sustained cardiac chest pain lasting more than 20 minutes. The ECG often shows abnormalities in T-waves or ST-segments. Cardiac enzymes are elevated, and the troponin test is positive.

ST-elevation myocardial infarction (STEMI) usually presents with typical cardiac chest pain suggestive of an acute myocardial infarction. The ECG reveals ST-segment elevation and the development of Q waves. Cardiac enzymes are elevated, and the troponin test is positive.

A summary of the vessels involved in different types of myocardial infarction, along with the corresponding ECG leads and the location of the infarction.

For instance, an anteroseptal infarction involving the left anterior descending artery is indicated by ECG leads V1-V3. Similarly, an anterior infarction involving the left anterior descending artery is indicated by leads V3-V4.

In cases of anterolateral infarctions, both the left anterior descending artery and the left circumflex artery are involved, and this is reflected in ECG leads V5-V6. An extensive anterior infarction involving the left anterior descending artery is indicated by leads V1-V6.

Lateral infarcts involving the left circumflex artery are indicated by leads I, II, aVL, and V6. Inferior infarctions, on the other hand, involve either the right coronary artery (in 80% of cases) or the left circumflex artery (in 20% of cases), and this is shown by leads II, III, and aVF.

In the case of a right ventricular infarction, the right coronary artery is involved, and this is indicated by leads V1 and V4R. Lastly, a posterior infarction involving the right coronary artery is shown by leads V7-V9.

Post myocardial infarction ventricular septal defect (VSD) is a rare but serious complication that occurs when the cardiac wall ruptures. It typically develops 2-3 days after a heart attack, and if left untreated, 85% of patients will die within two months. The murmur associated with VSD is a continuous sound throughout systole, and it is loudest at the lower left sternal edge. A palpable vibration, known as a thrill, is often felt along with the murmur.

Dressler’s syndrome, on the other hand, is a type of pericarditis that occurs 2-10 weeks after a heart attack or cardiac surgery. It is characterized by sharp chest pain that is relieved by sitting forwards. Other signs of Dressler’s syndrome include a rubbing sound heard when listening to the heart, pulsus paradoxus (an abnormal drop in blood pressure during inspiration), and signs of right ventricular failure.

Mitral regurgitation also causes a continuous murmur throughout systole, but it is best heard at the apex of the heart and may radiate to the axilla (armpit).

Tricuspid stenosis, on the other hand, causes an early diastolic murmur that is best heard at the lower left sternal edge during inspiration.

Lastly, mitral stenosis causes a rumbling mid-diastolic murmur that is best heard at the apex of the heart. To listen for this murmur, the patient should be in the left lateral position, and the stethoscope bell should be used during expiration.

One of the clinical features of mitral stenosis is malar flush, which refers to a reddening or flushing of the cheeks. Other clinical features include a mid-late diastolic murmur that is best heard during expiration, a loud S1 heart sound with an opening snap, a low volume pulse, atrial fibrillation, and signs of pulmonary edema such as crepitations or the presence of white or pink frothy sputum.

Further Reading:

Mitral Stenosis:
– Causes: Rheumatic fever, Mucopolysaccharidoses, Carcinoid, Endocardial fibroelastosis
– Features: Mid-late diastolic murmur, loud S1, opening snap, low volume pulse, malar flush, atrial fibrillation, signs of pulmonary edema, tapping apex beat
– Features of severe mitral stenosis: Length of murmur increases, opening snap becomes closer to S2
– Investigation findings: CXR may show left atrial enlargement, echocardiography may show reduced cross-sectional area of the mitral valve

Mitral Regurgitation:
– Causes: Mitral valve prolapse, Myxomatous degeneration, Ischemic heart disease, Rheumatic fever, Connective tissue disorders, Endocarditis, Dilated cardiomyopathy
– Features: pansystolic murmur radiating to left axilla, soft S1, S3, laterally displaced apex beat with heave
– Signs of acute MR: Decompensated congestive heart failure symptoms
– Signs of chronic MR: Leg edema, fatigue, arrhythmia (atrial fibrillation)
– Investigation findings: Doppler echocardiography to detect regurgitant flow and pulmonary hypertension, ECG may show signs of LA enlargement and LV hypertrophy, CXR may show LA and LV enlargement in chronic MR and pulmonary edema in acute MR.

Aortic sclerosis is a condition that occurs when the aortic valve undergoes senile degeneration. Unlike aortic stenosis, it does not result in any obstruction of the left ventricular outflow tract. To differentiate between aortic stenosis and aortic sclerosis, the following can be used:

Feature: Aortic stenosis
– Symptoms: Can be asymptomatic, but may cause angina, breathlessness, and syncope if severe.
– Pulse: Slow rising, low volume pulse.
– Apex beat: Sustained, heaving apex beat.
– Thrill: Palpable thrill in the aortic area can be felt.
– Murmur: Ejection systolic murmur loudest in the aortic area.
– Radiation: Radiates to carotids.

Feature: Aortic sclerosis
– Symptoms: Always asymptomatic.
– Pulse: Normal pulse character.
– Apex beat: Normal apex beat.
– Thrill: No thrill.
– Murmur: Ejection systolic murmur loudest in the aortic area.
– Radiation: No radiation.

Patients with mitral regurgitation can go for extended periods without experiencing any symptoms. They may have a normal exercise tolerance and show no signs of congestive cardiac failure. However, when cardiac failure does occur, patients often complain of breathlessness, especially during physical exertion. They may also experience fatigue, difficulty breathing while lying flat (orthopnoea), and sudden episodes of difficulty breathing at night (paroxysmal nocturnal dyspnoea).

In terms of clinical signs, mitral regurgitation can be identified through various indicators. These include a displaced and volume loaded apex beat, which can be felt during a physical examination. A palpable thrill may also be detected at the apex. Additionally, a pansystolic murmur, which is loudest at the apex and radiates to the axilla, can be heard. This murmur is typically most pronounced when the patient holds their breath during expiration. Furthermore, a soft first heart sound and signs of left ventricular failure may be present.

Hypothermia can cause various changes in an electrocardiogram (ECG). These changes include a slower heart rate (bradycardia), the presence of Osborn waves (also known as J waves), a prolonged PR interval, a widened QRS complex, and a prolonged QT interval. Additionally, shivering artifact, ventricular ectopics (abnormal heartbeats originating from the ventricles), and even cardiac arrest (ventricular tachycardia, ventricular fibrillation, or asystole) may occur.

Further Reading:

Hypothermic cardiac arrest is a rare situation that requires a tailored approach. Resuscitation is typically prolonged, but the prognosis for young, previously healthy individuals can be good. Hypothermic cardiac arrest may be associated with drowning. Hypothermia is defined as a core temperature below 35ºC and can be graded as mild, moderate, severe, or profound based on the core temperature. When the core temperature drops, basal metabolic rate falls and cell signaling between neurons decreases, leading to reduced tissue perfusion. Signs and symptoms of hypothermia progress as the core temperature drops, initially presenting as compensatory increases in heart rate and shivering, but eventually ceasing as the temperature drops into moderate hypothermia territory.

ECG changes associated with hypothermia include bradyarrhythmias, Osborn waves, prolonged PR, QRS, and QT intervals, shivering artifact, ventricular ectopics, and cardiac arrest. When managing hypothermic cardiac arrest, ALS should be initiated as per the standard ALS algorithm, but with modifications. It is important to check for signs of life, re-warm the patient, consider mechanical ventilation due to chest wall stiffness, adjust dosing or withhold drugs due to slowed drug metabolism, and correct electrolyte disturbances. The resuscitation of hypothermic patients is often prolonged and may continue for a number of hours.

Pulse checks during CPR may be difficult due to low blood pressure, and the pulse check is prolonged to 1 minute for this reason. Drug metabolism is slowed in hypothermic patients, leading to a build-up of potentially toxic plasma concentrations of administered drugs. Current guidance advises withholding drugs if the core temperature is below 30ºC and doubling the drug interval at core temperatures between 30 and 35ºC. Electrolyte disturbances are common in hypothermic patients, and it is important to interpret results keeping the setting in mind. Hypoglycemia should be treated, hypokalemia will often correct as the patient re-warms, ABG analyzers may not reflect the reality of the hypothermic patient, and severe hyperkalemia is a poor prognostic indicator.

Different warming measures can be used to increase the core body temperature, including external passive measures such as removal of wet clothes and insulation with blankets, external active measures such as forced heated air or hot-water immersion, and internal active measures such as inhalation of warm air, warmed intravenous fluids, gastric, bladder, peritoneal and/or pleural lavage and high volume renal haemofilter.

The timing of the initial rise, peak, and return to normality of various cardiac enzymes can serve as a helpful guide. Creatine kinase, the main cardiac isoenzyme, typically experiences an initial rise within 4-8 hours, reaches its peak at 18 hours, and returns to normal within 2-3 days. Myoglobin, which lacks specificity due to its association with skeletal muscle damage, shows an initial rise within 1-4 hours, peaks at 6-7 hours, and returns to normal within 24 hours. Troponin I, known for its sensitivity and specificity, exhibits an initial rise within 3-12 hours, reaches its peak at 24 hours, and returns to normal within 3-10 days. HFABP, or heart fatty acid binding protein, experiences an initial rise within 1.5 hours, peaks at 5-10 hours, and returns to normal within 24 hours. Lastly, LDH, predominantly found in cardiac muscle, shows an initial rise at 10 hours, peaks at 24-48 hours, and returns to normal within 14 days.