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.
Hypoxia Hypoxia is a lack of
oxygen delivery to the
heart, brain and other
vital organs. Rapid assessment of airway patency and respiratory effort must be performed. If the patient is mechanically ventilated, the presence of breath sounds and the proper placement of the endotracheal tube should be verified. Treatment may include providing oxygen, proper ventilation, and good
CPR technique. In cases of
carbon monoxide poisoning or
cyanide poisoning,
hyperbaric oxygen may be employed after the patient is stabilized.
Acidosis Acidosis (
hydrogen cation excess) is an abnormal pH in the body as a result of
lactic acidosis which occurs in prolonged hypoxia and in severe infection,
diabetic ketoacidosis, kidney failure causing
uremia, or ingestion of toxic agents or overdose of pharmacological agents, such as
aspirin and other
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.
Hyperkalemia or hypokalemia Hyperkalemia (excess) and
hypokalemia (inadequate) potassium can be life-threatening. A common presentation of hyperkalemia is in the patient with
end-stage renal disease who has missed a
dialysis appointment and presents with
weakness,
nausea, and broad
QRS complexes on the
electrocardiogram. (Note however that patients with
chronic kidney disease are often more tolerant of high potassium levels as their body often adapts to it.) Several medications, for example the antibiotic
trimethoprim/sulfamethoxazole or an
ACE inhibitor, can also lead to the development of significant hyperkalemia. The electrocardiogram will show tall, peaked T waves (often larger than the R wave) or can degenerate into a sine wave as the QRS complex widens. Immediate initial therapy is the administration of
calcium, either as
calcium gluconate or
calcium chloride. This stabilizes the electrochemical potential of cardiac myocytes, thereby preventing the development of fatal arrhythmias. This is, however, only a temporizing measure. Other temporizing measures may include
nebulized salbutamol, intravenous
insulin (usually given in combination with
glucose), and
sodium bicarbonate which all temporarily drive potassium into the interior of cells. Definitive treatment of hyperkalemia requires actual excretion of potassium, either through urine (which can be facilitated by administration of
loop diuretics such as
furosemide) or in the stool (which is accomplished by giving
sodium polystyrene sulfonate enterally, where it will bind potassium in the GI tract.) Severe cases will require emergent
hemodialysis. The diagnosis of
hypokalemia (not enough
potassium) can be suspected when there is a history of
diarrhoea or
malnutrition. Loop
diuretics may also contribute. The
electrocardiogram may show flattening of T waves and prominent U waves.
Hypokalemia is an important cause of acquired
long QT syndrome, and may predispose the patient to
torsades de pointes.
Digitalis use may increase the risk that
hypokalemia will produce life-threatening
arrhythmias. Hypokalemia is especially dangerous in patients with
ischemic heart disease.
Hypothermia Hypothermia is a low
core body temperature, defined clinically as a temperature of less than 35 degrees Celsius (95 degrees Fahrenheit). The patient is re-warmed either by using a
cardiac bypass or by irrigation of the body cavities (such as thorax, peritoneum, bladder) with warm fluids; or warmed
IV fluids.
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."
Hypoglycemia Hypoglycemia was removed from the Hs and Ts by the American Heart Association in their 2010 ACLS update. The association between hypoglycemia and sudden cardiac death is unclear. Moderate and severe hypoglycemia were both associated with increased mortality; however, giving dextrose is also associated with worse outcomes in one trial. ==Ts==