Hypothermia, Alpha Stat, and pH Stat Overview

These flashcards cover essential vocabulary and concepts related to hypothermia, Alpha Stat, pH Stat, and their physiological impacts.

Hypothermia

A medical condition characterized by an abnormally low body temperature.

Mild Hypothermia

Defined as a body temperature between 32-37°C.

Moderate Hypothermia

Defined as a body temperature between 28-31°C.

Deep Hypothermia

Defined as a body temperature between 18-28°C.

Profound Hypothermia

Defined as a body temperature between 0-18°C.

Prolonged ACT

An increase in activated clotting time due to inadequate heparinization during cardiopulmonary bypass.

Cardiopulmonary Bypass (CPB) Contraindications

Asphyxia and patient temperature below 15°C are contraindications for CPB in cases of accidental hypothermia.

CO2 and Hypothermia

Carbon dioxide levels decrease with the presence of hypothermia.

SVR and Hypothermia

Systemic vascular resistance increases due to increased blood viscosity during hypothermia.

Cardiac Index in Hypothermia

Cardiac index is appropriately decreased during induced hypothermia.

Autoregulation Shutdown Temperature

Autoregulation of blood flow ceases at temperatures between 20-22°C.

Rewarming Metabolism

Metabolism assists in rewarming at temperatures of 32°C and above.

Heart Fibrillation Temperature

The heart begins to fibrillate at a temperature of 32°C.

Temperature and CO2 Solubility

Decreased temperature increases the solubility coefficient of CO2 in plasma.

Temperature and Metabolism

An increase in temperature leads to an increase in metabolic rate.

Metabolism Decrease with Temperature

Metabolism decreases by 7% for every 1°C change and 50% with a 7°C change.

Oxygen Demand at 37°C

The heart has increased oxygen demand and works more at 37°C.

Water Exposure Temperature of 18°C

Use a temperature gradient of 8-10 degrees when a patient falls into water at this temperature.

Gaseous Micro Emboli

Maintaining an 8-10 degree temperature gradient reduces the risk of gaseous micro emboli.

Alpha Stat

Maintains alkalosis and is kept at a target temperature of 37°C.

pH Stat

Utilizes CO2 for cerebral vasodilation and is temperature corrected.

pH Stat Conditions

If a patient is at 28°C, CO2 levels will be high and pH levels low if not temperature corrected.

Alpha Stat and pH Stat

Alpha stat maintains constant pH while pH stat is temperature corrected.

Alpha Stat Measurement

The measurements for alpha stat are taken at 37°C.

Poikilotherms

Organisms that cannot regulate body temperature except through behavioral means.

Cooling and Rewarming Recommendations

Use pH stat during initial cooling and alpha stat during rewarming for brain protection.

Metabolic Rate Change with Cooling

The metabolic rate decreases by 7% for each degree Celsius cooled.

Safe Circulatory Arrest Time

The safest circulatory arrest time at a temperature of 18°C is 60 minutes.

Viscosity and Temperature

Viscosity of blood increases as temperature decreases.

Oxygen Saturation and Temperature

Oxygen saturation increases with decreased temperature due to increased affinity of hemoglobin.

Blood Cooling Effects

Blood cooled from 37°C increases solubility of CO2 and decreases PaCO2.

Risks of Inadequate Warming

Hypothermic patients are prone to cardiac arrhythmias if not adequately warmed.

Heparin Elimination and Hypothermia

Hypothermia has a general effect of delayed elimination of heparin.

Potassium and Hypothermia

A drop in potassium levels during hypothermia is associated with increased uptake by cells.

Q10 Definition

The change in metabolic reaction rate for every 10 degree temperature change.

Nasopharyngeal Temperature Correlation

Nasopharyngeal temperature best correlates with brain temperature.

Cooling Rate Risks

Cooling too fast can lead to intervascular aggregation at 1°C per minute.

Warming Risks

Warming too quickly or continued shivering can lead to electrolyte shifts and arrhythmias.

Chemotherapeutic Perfusion Temperature

Recommended to maintain between 38-41°C.

Celsius to Fahrenheit Conversion

To convert Celsius to Fahrenheit use the formula °C * 1.8 + 32.00.