Waking up During Surgery - Chances, Risks, and Prevention

Introduction

Waking up during surgery is also called anesthesia awareness. It leads to an unintentional recall of events during an intra-operative procedure. It leaves a deep psychological impact on a patient. It usually happens due to an inadequate depth of anesthesia.

What Are the Chances of Waking up During Surgery?

The incidence is rare. It occurs in one or two out of 1000 individuals receiving general anesthesia (GA). However, it is a serious adverse event in which patients may have vague dreams, difficulty breathing, pain during surgery, and dreams of impending death. Patients even claim to remember the conversations during surgery.

What Are the Risk Factors of Waking up During Surgery?

The risk factors have yet to be fully discovered. However, some potential factors are listed below.

1. Anesthesia-Related: Various anesthesia techniques can be considered risk factors.

• Neuromuscular Blockade (NMB): (NMB) accounts for most of the reported anesthesia awareness cases. NMB blocks the nerve impulses to muscles. It results in paralysis as patient movement is blocked. This patient's experience of muscle paralysis is new and dreadful.

• Total Intravenous Anaesthesia (TIVA): TIVA is the IV- intravenous injection (into the vein) of anesthetic agents for general anesthesia. The contributing factors to anesthesia awareness during TIVA are problems in IV agent delivery. An example is the failure of apt drug delivery from a peripheral (arm, leg) intravenous administration site due to an obscured view. Technical difficulties in anesthetic delivery are another reason. An infusion programming pump delivers anesthetic drugs. An error in the pump programming is a factor.

• Inhalational Anesthesia: Anesthesia vaporizer is an equipment to deliver anesthetic gas. Failure to turn on or refill a vaporizer is an error. There can also be an inherent problem in the machine.

2. Surgery-Related: Emergency surgery poses a high risk for anesthesia awareness. It is especially true in trauma and emergency cesarian section (C-section) surgery. Therefore, a decreased anesthetic dose is required in these procedures.

• In an emergency trauma setting, excessive blood loss is inevitable. Blood loss leads to a decrease in blood pressure that causes inadequate blood flow to all organs, also called hemodynamic instability. Hence, such an event prevents a deeper level of anesthesia.

• Emergency C-section also results in a scenario where general anesthesia is sometimes intentionally withheld. It is because general anesthetics can cross the placental barrier and cause a circulatory and respiratory upset in the baby. Hence, lighter anesthesia is given.

• Cardiopulmonary bypass (CPB) and open heart surgery are other surgeries with an increased risk.

3. Patient-Related: Various patient-related factors are described.

• Genetic resistance has been reported to increase the risk of intra-operative awareness.

• Long-term abuse of alcohol, opioids, and benzodiazepines increase the anesthetic requirement. Hence, incomplete information about the patient with substance abuse can be risky.

• There are three phases of anesthesia: induction, maintenance, and recovery. Anesthesia awareness has been reported to be most common during the induction and recovery phase. Airway placement is technique-sensitive in inhalational anesthesia. It is particularly difficult in obese patients. Hence, they are at greater risk due to a delay in the delivery of the anesthetic agent.

• Chronic heart condition patients are also a high-risk category due to the anesthetic dose reduction strategies to maintain hemodynamic function.

What Are the Effects of Waking up During Surgery on Patients?

The effects of anesthesia awareness are profound.

1. Effects On Patients - Anesthetic awareness is linked to psychological consequences. The acute aftereffects are sleep disturbances, flashbacks, and nightmares. Long-term psychological effects are depression and anxiety. These are known to affect about 33 % of the patients with anesthesia awareness. In addition, post-traumatic stress disorder (PTSD) occurs in some patients. It consists of repeated nightmares, anxiety, and irritability.
2. Medicolegal Implications - Among many other reasons, anesthesiologists are legally implicated in anesthesia awareness. Therefore, an anesthesiologist must be aware of certain signs during surgery, including sweating, eye tearing, a rise in blood pressure, and pupillary light reflex.

How Can Anesthesia Awareness Be Prevented?

Several steps are recommended to prevent anesthesia awareness. Some important measures are given below.

1. Preinduction Steps: A thorough history is of paramount importance. It includes the patient’s medical history, allergies, substance abuse, and prior history of surgery.

• Premedication: The preventive administration of benzodiazepines (BZDs) during cardiac, trauma, and emergency procedures is beneficial. However, the BZD administration might lead to a delayed recovery.

• Careful Checking of Anesthesia Delivery System: The functioning of infusion pumps, vaporizers, intravenous lines, and gas flow systems should be meticulously done. Regular maintenance and calibration are essential.

2. Intraoperative Monitoring: It is difficult to assess anesthesia awareness during the intraoperative period. Proper clinical techniques, conventional monitoring, and brain function monitors can reduce the risk.

• Clinical Techniques: These include checking for movement, command response, respiratory rate, and eye response.

• Monitoring Systems: Electrocardiography (ECG), heart rate, blood pressure, end-tidal anesthetic analysis, and capnography are some monitoring systems. End-tidal anesthesia is a clinical predictor for anesthesia recovery. It is used in inhalational anesthesia. Capnography measures respiratory gases. Constant monitoring prevents hypoxia (low blood oxygen level). Guedel has laid out the stages of anesthesia. Reaching stage III is mandatory before commencing surgery.

• Brain Electrical Activity Monitoring: Many devices are designed to record brain activity during anesthesia. The bispectral index (BIS) monitoring involves placing four electrodes on the forehead. Brain activity is checked through electroencephalography (EEG). Data are displayed on a screen as numbers. The values range from 0 to 100. A value of 0 represents no brain activity. On the other hand, 100 denotes an awake state. A value of 40 to 60 shows proper general anesthesia. Therefore, a value under 60 decreases the risk of anesthesia awareness. BIS also determines the electromyographic (assesses a muscle response) activity of the frontalis muscle.

3. Postoperative Steps: Many patients do not report the event voluntarily. Hence, a structured interview must be conducted for such patients at several intervals. An open-ended discussion with the patient’s perspective is important. The immediate postoperative interview should occur in front of the surgeons and anesthesiologists. Counseling must be offered to patients suffering from anesthesia awareness.

Conclusion

There is no gold standard in monitoring patient awareness during surgery. However, the incorporation of a few measures can decrease the incidence. Still, intraoperative awareness is a distressing complication for the patient. Therefore, an interprofessional team of anesthesiologists, nurses, and surgeons must understand the associated risk factors. Also, psychological counseling and support should be offered if a patient experiences this phenomenon.