Which of the following factors can trigger malignant hyperthermia in susceptible individuals?

Choice A rationale

This statement is incorrect because hyperacute rejection occurs almost immediately, usually within minutes to hours after the graft is vascularized. It does not take several days to develop; that timeframe is more characteristic of acute rejection, which typically occurs within the first few weeks or months. Hyperacute rejection is a rapid and violent immune response that happens while the patient is still in the operating room or very shortly after the surgical procedure is completed.

Choice B rationale

This statement is false because hyperacute rejection is generally irreversible. Once the process begins, the damage to the transplanted organ is so severe and rapid that increasing immunosuppressive medications like corticosteroids or monoclonal antibodies will not save the graft. The only effective treatment for hyperacute rejection is the immediate surgical removal of the transplanted organ to prevent a systemic inflammatory response and further complications for the recipient, who must then return to dialysis.

Choice C rationale

This is the correct statement. Hyperacute rejection is caused by pre-existing recipient antibodies that react against the donor's antigens, specifically the ABO blood group or human leukocyte antigens. This binding triggers the complement system and a massive inflammatory cascade. This leads to widespread endothelial damage, platelet aggregation, and capillary thrombosis within the new organ. The resulting ischemia and necrosis cause the organ to turn blue or mottled almost immediately after blood flow is restored.

Choice D rationale

This statement is inaccurate because the symptoms of hyperacute rejection are immediate rather than occurring within two weeks. While fever and pain at the transplant site can occur, they happen immediately. The two-week timeframe is much more common for acute rejection, which is mediated by T-cells rather than pre-existing antibodies. Hyperacute rejection is now rare due to improved cross-matching techniques that identify these pre-formed antibodies before the transplant surgery is ever performed.

Choice A rationale

This statement is incorrect because hot, dry skin is a hallmark characteristic of heat stroke rather than heat exhaustion. In heat stroke, the body's thermoregulatory mechanisms fail entirely, and the person stops sweating, leading to a dangerous rise in core body temperature, often exceeding 104 degrees Fahrenheit or 40 degrees Celsius. In contrast, patients experiencing heat exhaustion are typically still able to sweat profusely as their body attempts to dissipate heat through the process of evaporation.

Choice B rationale

Heat exhaustion often involves hypotension and tachycardia as the body attempts to compensate for significant fluid and electrolyte loss. Excessive sweating leads to a decrease in intravascular volume, which lowers blood pressure. The heart rate increases as a compensatory mechanism to maintain cardiac output and perfusion to vital organs. These clinical findings are essential for differentiating exhaustion from simpler heat cramps. Understanding these hemodynamics helps the nurse prioritize fluid resuscitation to prevent the progression to life-threatening heat stroke.

Choice C rationale

Altered mental status, confusion, seizures, or coma are definitive characteristics of heat stroke that distinguish it from heat exhaustion. As the core body temperature rises to critical levels, the central nervous system becomes impaired due to thermal injury and cerebral edema. While a person with heat exhaustion may feel weak or dizzy, they generally remain cognitively intact. The presence of neurological dysfunction signifies a medical emergency requiring immediate and aggressive cooling measures to prevent permanent brain damage or multi-organ failure.

Choice D rationale

Excessive sweating and clammy, pale skin are classic signs of heat exhaustion. During this stage, the thermoregulatory system is still functioning but is overwhelmed by the heat load and fluid depletion. The skin feels cool and moist because the body is still pushing blood to the periphery to encourage cooling through sweat. Normal lab parameters for sodium are 135 to 145 mEq/L, and these levels can fluctuate significantly during heat-related illnesses, requiring careful monitoring and replacement during treatment. .