Hs and Ts

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The Hs and Ts is a mnemonic used to aid in remembering the possible reversible causes of cardiac arrest.[1] A variety of disease processes can lead to a cardiac arrest; however, they usually boil down to one or more of the "Hs and Ts".[2][3][4]

Hs

Hypovolemia

Hypovolemia is a result of a lack of circulating body fluids, principally blood volume. This is usually (though not exclusively) caused by some form of bleeding, anaphylaxis, or pregnancy with gravid uterus. Peri-arrest treatment includes giving IV fluids and blood transfusions, and controlling the source of any bleeding - by direct pressure for external bleeding, or emergency surgical techniques such as esophageal banding, gastroesophageal balloon tamponade (for treatment of massive gastrointestinal bleeding such as in esophageal varices), resuscitative thoracotomy in cases of penetrating trauma or significant shear forces applied to the chest, or exploratory laparotomy in cases of penetrating trauma, spontaneous rupture of major blood vessels, or rupture of a hollow viscus in the abdomen.[citation needed]

Hypoxia

hyperbaric oxygen may be employed after the patient is stabilized.[citation needed
]

Acidosis

salicylates, ethanol, ethylene glycol and other alcohols, tricyclic antidepressants, isoniazid, or iron sulfate. This can be treated with proper ventilation, good CPR technique, buffers like sodium bicarbonate, and in select cases may require emergent hemodialysis.[citation needed
]

Hyperkalemia or hypokalemia

Hyperkalemia (excess) and hypokalemia (inadequate) potassium can be life-threatening.

A common presentation of hyperkalemia is in the patient with

sodium polystyrene sulfonate enterally, where it will bind potassium in the GI tract.) Severe cases will require emergent hemodialysis.[citation needed
]

The diagnosis of

ischemic heart disease.[citation needed
]

Hypothermia

CPR only is given until the core body temperature reaches 30 degrees Celsius, as defibrillation is ineffective at lower temperatures. Patients have been known to be successfully resuscitated after periods of hours in hypothermia and cardiac arrest, and this has given rise to the often-quoted medical truism, "You're not dead until you're warm and dead."[citation needed
]

Hypoglycemia

There is an unclear association between hypoglycemia and sudden cardiac death. In the NICE-SUGAR trial,[5] moderate and severe hypoglycemia were both associated with increased mortality. However, administration of dextrose is also associated with worse outcomes.[5]

Hypoglycemia was removed from the Hs and Ts by the American Heart Association in their 2010 ACLS update.[6]

Ts

Tablets or toxins

medical records to make sure no interacting drugs were prescribed, or sending blood and urine samples to the toxicology lab for report. Treatment may include specific antidotes, fluids for volume expansion, vasopressors, sodium bicarbonate (for tricyclic antidepressants), glucagon or calcium (for calcium channel blockers), benzodiazepines (for cocaine), or cardiopulmonary bypass. Herbal supplements and over-the-counter medications should also be considered, alongside narcotics.[7]

Cardiac tamponade

In

echocardiogram. This is treated in an emergency by inserting a needle into the pericardium to drain the fluid (pericardiocentesis), or if the fluid is too thick then a subxiphoid window is performed to cut the pericardium and release the fluid.[citation needed
]

Tension pneumothorax

hypoxia, jugular venous distension, hyperresonance to percussion on the affected side, and a tracheal shift away from the affected side. The tracheal shift often requires a chest x-ray to appreciate (although treatment should be initiated prior to obtaining a chest x-ray if this condition is suspected). This is relieved by a needle thoracostomy (inserting a needle catheter) into the 2nd intercostal space at the mid-clavicular line, which relieves the pressure in the pleural cavity.[citation needed] Critical care teams also have the skill to incise the chest in the 5th intercostal space in the mid-axillary line, to evacuate air with a larger breach of the pleura. However, this is associated with a range of potential complications.[8]

Thrombosis (myocardial infarction)

In thrombosis (myocardial infarction), if the patient can be successfully resuscitated, there is a chance that the myocardial infarction can be treated, either with thrombolytic therapy or percutaneous coronary intervention.

Thromboembolism

In

thrombolytics can be attempted, and some specialized centers may perform thrombectomy
, however, prognosis is generally poor.

Trauma

Main article:
Trauma (medicine)

Cardiac arrest can also occur after a hard blow to the chest at a precise moment in the cardiac cycle, which is known as commotio cordis. Other traumatic events such as high speed car crashes can cause sufficient structural damage to induce arrest.

Alternative mnemonic

An alternative, more practical, mnemonic for reversible causes of cardiac arrest is ABCD-Ultrasound:[9]

References

  1. ^ Resuscitation Council UK (2005). Resuscitation Guidelines 2005 London: Resuscitation Council UK.
  2. ISBN 0-87493-341-2
    .
  3. ISBN 0-87493-424-9
    .
  4. ^ "2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care - Part 7.2: Management of Cardiac Arrest." Circulation 2005; 112: IV-58 - IV-66.
  5. ^
    PMID 22992074
    .
  6. ^ "Part 7: Adult Advanced Cardiovascular Life Support – ECC Guidelines". Eccguidelines.heart.org. Retrieved 2018-10-10.
  7. ^ "AED in de buurt van VVE". Aedmaster.nl. Retrieved 2021-04-20.
  8. PMID 34863280
    .
  9. ^
    doi:10.1097/01.EEM.0000758760.12428.35
    .
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