Atypical Clinical Presentation of Hypothermia Induced by Intrathecal Morphine in a Patient Who Underwent Total Knee Arthroplasty Under Spinal Anesthesia: A Case Report

This case report describes a 62-year-old male who experienced paradoxical hypothermia following an elective total knee replacement (TKR) performed under spinal anesthesia with intrathecal morphine administration. The patient presented with significant hypothermia, defined as a body temperature below 35°C, approximately 45 minutes following the administration of anesthesia. The condition demonstrated resistance to conventional rewarming techniques. This condition required symptomatic treatment, leading to the administration of naloxone. After receiving two doses of naloxone, the patient's temperature stabilized, and they experienced a reduction in diaphoresis, improved alertness, and less nausea. Given the scarce documentation on non-obstetric paradoxical hypothermic reactions to intrathecal morphine, this case highlights the critical need for careful temperature monitoring when administering spinal anesthesia with intrathecal opioids. Additionally, it highlights the unusual symptoms of hypothermia that can hinder diagnosis and treatment, stressing the need for increased awareness among anesthesiologists to achieve the best possible patient outcomes.