A hip fracture involves a break in the upper part of the thigh bone (femur), near the hip joint. Delirium, in contrast, is an acute state of confusion characterized by disturbances in attention, awareness, and thinking. Following a hip fracture, delirium is a common and serious complication, with reported incidences ranging from 16% to 62%. This condition significantly affects patient outcomes, leading to longer hospital stays, increased morbidity, and higher mortality rates.
The Body’s Immediate Response
A hip fracture causes intense physical and psychological stress. The severe pain can disorient and affect brain function, triggering the body’s stress response and releasing hormones like cortisol and adrenaline.
These hormones prepare the body for “fight or flight.” While beneficial in short-term emergencies, their prolonged elevation can disrupt brain chemistry and neurological function. This disruption contributes to agitation, lethargy, and confusion, which are characteristic features of delirium.
Impact of Medical Care
Medical interventions for treating a hip fracture can also contribute to delirium. Surgery imposes significant physical stress, leading to a widespread inflammatory response that can affect brain function and worsen confusion.
Anesthesia, whether general or regional, also plays a role. General anesthesia can temporarily alter brain activity, and its effects may linger, causing disorientation and cognitive impairment. Opioid medications, commonly used for pain management, can induce sedation and confusion as side effects, increasing the risk of delirium. Regional nerve blocks have shown promise in reducing opioid use and the incidence of delirium by managing acute pain before surgery.
Underlying Physiological Factors
Beyond immediate trauma and medical interventions, several physiological disruptions contribute to delirium after a hip fracture. Systemic inflammation can directly impair brain function by affecting neurotransmitter systems. Infections are common complications after hip fracture surgery and can exacerbate delirium.
Dehydration and electrolyte imbalances are frequent in hospitalized patients and can disrupt brain cell function, leading to confusion. Significant blood loss from the fracture or surgery can result in anemia, reducing oxygen delivery to the brain and causing cognitive impairment. The unfamiliar and often noisy hospital environment, coupled with frequent interruptions for medical care, can disrupt normal sleep patterns, contributing to disorientation and delirium.
Patient-Specific Risk Factors
Certain patient characteristics increase the likelihood of developing delirium following a hip fracture. Advanced age is a primary factor. Pre-existing cognitive impairment makes individuals susceptible due to a reduced cognitive reserve.
Taking multiple medications, known as polypharmacy, increases the risk due to potential drug interactions and cumulative side effects. A history of previous delirium episodes indicates a heightened vulnerability to future occurrences. Other contributing factors include poor baseline functional status and various co-morbidities, which can further compromise the body’s ability to cope with the stress of a fracture and surgery.