Postanesthetic Shivering - Clinical Impact and Treatment

Introduction

Postanesthetic shivering is a common yet important phenomenon in the world of medical operations and anesthesia. This unusual physiological reaction, characterized by uncontrollable trembling and shivering, can happen after operations and treatments requiring anesthesia. Postanesthetic shivering, though commonly dismissed as just a side effect, requires more consideration due to its possible effects on patient comfort, healing, and overall results.

What Is Postoperative Shivering?

The involuntary and rhythmic muscular activity that takes place during the early phases of recovery following anesthesia is referred to as postoperative shivering (PS). Rapid muscular contractions in the face, jaw, head, or other regions that continue for more than 15 seconds are known as shivering. The postanesthesia care unit commonly witnesses the phenomenon of postoperative shivering. It has been observed that postoperative shivering affects 20 to 70 percent of patients after general anesthesia, making it a common anesthetic complication.

What Are the Clinical Impacts of Postoperative Shivering?

• Uncomfortable Feelings and Anxiety:

  • Shivering during the recovery phase can be more uncomfortable than the actual surgery pain.

  • The chilly sensation felt during shivering is often quite uncomfortable for patients as they are still in the recovery phase.

  • PS is often disturbing for women who are into labor or have just delivered. It makes them anxious.

• Effect on Postoperative Recovery:

  • Surgery-related discomfort might be made worse by shivering, which can stretch surgical wounds.

  • Raises intraocular and intracranial pressures and hinders monitoring methods.

• Physiological Effects:

  • Increases cardiac output, heart rate, and arterial pressure by increasing oxygen consumption.

  • It produces carbon dioxide, and releases catecholamines (hormones produced by the adrenal glands. Dopamine, norepinephrine, and epinephrine are the three primary catecholamine subtypes and cause lactic acidosis.

  • The heat produced by metabolism can increase by as much as 600 percent.

• Hypoxemia and Oxygen Consumption:

  • The amount of oxygen consumed during shivering rises by 300 percent to 400 percent.

  • There is an increased risk of postoperative critical ischemia due to hypoxemia.

What Are the Effects Caused by Postanesthetic Shivering?

• Adrenergic Activities: Shivering can cause an increase in sympathetic and adrenergic activity, which can cause myocardial ischemia and other organ dysfunctions.

• Organ Dysfunction: Sympathetic hyperactivity brought on by shivering may cause organ dysfunction, especially myocardial ischemia.

• Postoperative Complications: Shivering has been connected to surgical problems, including infection, discomfort, and bleeding, which can make recovery time longer.

• Delayed Wound Healing: Shivering may cause a wound to take longer to heal, lengthening the patient's stay in the hospital.

• Metabolic Demands: Increased metabolic demands brought on by shivering present problems for individuals with intrapulmonary shunts, fixed cardiac output, or low respiratory reserve.

• Individuals Who Are Elderly: Shivering is uncommon in elderly individuals because normal thermoregulatory regulation is impaired with advancing age. When compared to younger patients, elderly and weak individuals have fewer severe unfavorable effects due to decreased shivering intensity.

What Is the Treatment of Postanesthetic Shivering?

• Non-Pharmacological Therapy: There have been reviews of several anti-shivering drugs. The negative effects of drugs, however, restrict their use in many therapeutic contexts. Pharmacotherapy can obstruct neurologic tests, impair clinical anesthesia recovery, and perhaps have an impact on hemodynamic and neurologic conditions. As a result, non-pharmacologic anti-shivering techniques are frequently utilized in place of drugs.

  • The mechanism of action of non-pharmacological therapy is either to keep or raise body temperature beyond the shivering threshold or to block the central shivering reaction via heated skin sensory input.

  • Active cutaneous warming strategies, as mentioned below, are used to effectively control perioperative and induced hypothermia shivering:

    • Electric heating.

    • Forced-air systems.

    • Radiant heating.

  • Approaches for passive cutaneous warming, such as cotton blankets and elastic bandages, are not very effective.

  • Based on the research that is currently available, body core warming techniques like hot fluid and heated air give little benefit.

  • Active cutaneous warming includes increasing the body's internal heat content to reduce the transmission of heat from the core to the periphery and minimize radiant heat loss. This all-encompassing strategy efficiently controls thermoregulatory shivering. The input from cutaneous thermoreceptors, which accounts for around 20 percent of the total shivering response, is also interfered with by surface warming. While raising the surrounding temperature can help reduce shivering, it is insufficient on its own.

• Pharmacological Therapy: A complex system, including thermal receptors (temperature sensors), the spinal cord, the brain stem, the frontal region of the brain called the anterior hypothalamus, and the outer layer of the brain known as the cerebral cortex, meticulously regulates the body's temperature. A variety of medications, including opioids, alpha 2-agonists, anticholinergics, central nervous system stimulants, and corticosteroids, are used in the prevention and treatment of post-anesthetic shivering.

  • Highly Effective Antishivering Medications:

    • Centrally Acting Analgesics: Tramadol.

    • Opioid Receptor Agonists: Meperidine, Fentanyl.

    • Cholinesterase Inhibitors: Physostigmine.

    • N-methyl-D-aspartate (NMDA) Receptor Antagonists: Ketamine and Magnesium sulfate.

  • Relatively Less Effective Antishivering Medications:

    • Alpha 2-Central Agonists: Clonidine, Dexmedetomidine.

    • Antiserotonergic Agents: Ondansetron.

    • Anti-inflammatory Drugs: Dexamethasone.

• The effectiveness of drugs that affect the thermoregulatory loop at several levels is often higher. Multiple modes of action are common in highly effective classes. Opioid agonists and NMDA antagonists are more effective than drugs that just affect a specific function or the peripheral nervous system.

Conclusion

In conclusion, postanesthetic shivering is a common physiological reaction that might happen following anesthesia and surgery. Although the specific underlying mechanisms are not entirely known, they are impacted by things like the patient's ability to regulate their body temperature; the anesthetics used, and the surgical operation itself. Patients who have postanesthetic shivering may feel uncomfortable and distressed, which might result in consequences including higher oxygen use, a slower rate of recovery, and general unhappiness with the surgical procedure. Healthcare professionals must keep a close eye on patients who are showing symptoms of post-anesthetic shivering and take aggressive measures to treat this problem. Healthcare professionals may lessen the effects of postanesthetic shivering and help their patients recover more quickly by using a mix of prophylactic measures and focused treatments.