Delayed Awakening From Anesthesia - An Overview

What Is Delayed Awakening From Anesthesia?

Recovery after general anesthesia is defined as a condition of consciousness in which a patient awakens or becomes aroused and aware of their surroundings and identity. In the majority of instances, this occurs shortly after the conclusion of anesthesia; however, when it occurs later, it offers a diagnostic problem and maybe a dangerous occurrence.

What Factors Contribute to a Delayed Recovery of Consciousness?

Pharmacological

• Overdose - Too much medication administered, or if the patient is very sensitive. Patients who are weak, slim, or elderly require lower doses than fit, normal-sized people. In renal or hepatic failure, medication metabolism is delayed, and lesser doses may be required. Certain agents may be more sensitive under certain circumstances.

• Type and Duration of Anesthesia - The speed of emergence of inhalational anesthetic drugs is closely linked to alveolar ventilation. Delays in emergence are often caused by hypoventilation. Faster emergence is inversely related to blood gas solubility, with less soluble substances like nitrous oxide and halothane being removed faster than ether. When anesthesia is prolonged, emergence affects total tissue uptake.

• Gaseous Anesthetics - Volatile anesthesia emerges after alveolar hypoventilation. Volatile anesthetics with a greater blood–gas partition coefficient are taken up more into the pulmonary circulation, delaying anesthesia recovery.

• Opioids - Opioids are drugs that are commonly used for pain management. Opioids can cause respiratory depression-induced hypercarbia or sedation.

• Neuromuscular Blockers - Neuromuscular blockers, often known as neuromuscular blocking agents, are pharmacological substances that selectively block neurological communication. Anesthesia-induced consciousness is unaffected by neuromuscular drugs. Neuromuscular blocks can mimic delayed consciousness recovery. Impaired ventilatory response to hypoxia caused by residual paralysis can delay awareness.

• Anticholinergic Syndrome - The central anticholinergic syndrome is caused by several drugs. Coma and stupor may postpone anesthesia emergence. Peripheral symptoms include dry mouth, tachycardia, and urine retention.

Metabolic Causes

• Glycemic Condition -The brain is an essential glucose consumer; hence, hypoglycemia can cause a delayed recovery from anesthesia. Infants, diabetics (especially those on insulin or oral hypoglycemic medicines), patients with hepatic failure or excessive alcohol use/abuse, and starved individuals are at risk of hypoglycemia. Hyperglycemia may delay anesthetic recovery. Diabetics who have stressful surgery or get I.V. steroids under general anesthesia may be in danger.

• Hyponatremia or Hypernatremia - Hyponatremia is a medical condition characterized by a lower-than-normal concentration of sodium. Surgery or anesthesia can cause hyponatremia.

• Hypothermia - All general anesthetics lower body temperature dose-dependently. Hypothermia lowers brain activity, medication metabolism, and minimum alveolar concentration. Patients getting general anesthesia for more than 30 minutes should have their temperature checked and recorded.

What Are the Risk Factors for Delayed Conscious Recovery?

Age Factor

• Aging influences the absorption, distribution, and metabolism due to the accumulation of organ system deficiencies.

• There is a likelihood of a prolonged time for restoration of consciousness following general anesthesia in older or weak patients who are more sensitive to medicines typically used during general anesthesia, such as intravenous (administration refers to the delivery of substances directly into the veins) and inhalational (process or action related to breathing) anesthetic agent.

• The causes are diverse and include a decline in CNS (central nervous system) function resulting in greater responsiveness to CNS-acting medicines, alterations in body composition with decreased muscular mass, an increase in fat tissue, and a decrease in total body water.

• Aging also affects renal (kidney) and hepatic metabolism, which may impair renal and hepatic clearance and, consequently, the duration of action of medicines depending on these excretion pathways.

Physical Constitution - The constitution of the body can significantly influence the rate of recovery following general anesthesia. As the majority of pharmacological doses should be based on lean body mass, increasing body fat in obese patients may necessitate the administration of substantially greater doses to achieve the same highest concentration compared to individuals with less body fat.

Comorbidities - Preexisting comorbidities may delay the restoration of consciousness following anesthesia.

• Pulmonary Condition - Respiratory comorbidity, either linked to brain function, neuromuscular function, or pulmonary, might increase the likelihood of a delayed restoration of consciousness following anesthesia due to hypoxia, hypercarbia, or delayed removal of inhaled drugs. This is exacerbated by medications known to decrease minute volume, including opioids and inhaled anesthetics. As a consequence of elevated lung water and reduced cardiac output, congestive heart failure can impede the elimination of anesthetic drugs.

• Hepatic Condition - Acute and chronic hepatic illness can significantly change the pharmacokinetics of several anesthetic medications and, if doses are not adjusted correctly, can increase the likelihood of delayed emergence. The risk of opioid buildup is increased in individuals with liver cirrhosis due to decreased hepatic blood flow, decreased extraction ratios, decreased plasma protein binding, and increased distribution volumes.

• Renal Condition - Acute and chronic renal impairment affects the pharmacokinetics of several drugs used during general anesthesia, hence increasing the risk of delayed return to consciousness. In hepatic illness, failing to adjust medicine dosages correctly may increase the duration of the therapeutic effect. Individuals who have renal impairment take a lower dose of thiopental due to decreased plasma binding affinity and greater volume of distribution.

• Other Conditions - Hypothyroidism has multisystem consequences, including decreased spontaneous minute breathing, decreased plasma volume, hyponatremia, and poor hepatic drug metabolism, all of which can raise the likelihood of delayed return of consciousness following anesthesia. Myxoedema coma is a known cause of the prolonged return of consciousness, and subclinical hypothyroidism has also been documented to manifest as a prolonged restoration of consciousness after anesthesia.

What Is the Measure to Improve the Condition?

• Monitoring- Due to the difficulties of forecasting the incidence and its many etiologies, accurate intraoperative monitoring methods and an adequate operational strategy like hypothermia prevention are essential for prevention. Intraoperative neuromuscular monitoring is crucial, while brain monitoring of anesthesia through processed EEG-based devices can be useful in the awakening phase, but a difficult-to-quantify disturbance presumably caused by subcorticality. Regulations of the sleep-wake cycle can impact the dependability of systems during an AE.

• Initial Assessment - The individual is intubated, mechanical breathing, oxygenation, and maintaining sustainability are treated. This initial assessment must involve body temperature verification. Protect airways and assess awareness of delayed waking. The causes must also be considered.

• Physical Examination - It evaluates spontaneous ventilation, pupil size (although numerous drugs may impact pupillary reactions, spontaneous or provoked movements, cough and gag reflexes, and responsiveness to external stimuli, including verbal input and tactile stimulation. Regional ischemia may cause localized symptoms or decerebration on the neurological exam.

• Reassess the Medical History - This includes older age, body habits, history of hypertension, prior psychological illnesses, neurologic conditions such as seizures or cerebral vascular abnormalities, and unusual neurologic disorders. This rapidity includes previous heart and pulmonary disease, renal or hepatic disease, subclinical or clinical hypothyroidism, and metabolic changes. Herbal drugs are used two to three weeks before surgery.

• Review the Anesthetic Record - Drug administration, general anesthesia, and unexpected intraoperative events must be assessed. Although women recover faster than men, men may experience longer awakenings.

Conclusion

An extended period of unconsciousness following anesthesia is a substantial challenge for anesthesiologists, who must act quickly to investigate potential causes and begin treatment for the patient. A patient's risk of a delayed return to consciousness can be affected by several patient-related, pharmaceutical, and surgical variables; nevertheless, once the condition has been identified, the vast majority of instances can be treated very quickly. After the problem has formed, it can be helpful to conduct a comprehensive investigation of the possible causes to facilitate the rapid settlement of the issue. In exceedingly unusual cases, a diagnostic expansion may be necessary since the primary issue of the condition may be serious brain damage, which is extremely rare.