Understanding the Risks of Deep Sedation in Medical Procedures

In the past, medical diagnostic and surgical procedures were dreaded because of the unbearable discomfort associated with these clinical processes. Fortunately, thanks to advancements in the medical field, physicians have several ways to guarantee their patient’s comfort during these procedures. One of the common pain control methods physicians use is sedation. Also known as monitored anesthesia care, sedation falls under three main levels: minimal, moderate (conscious), and deep sedation.

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Deep sedation is controlled or monitored unconsciousness or depressed consciousness in which the patient isn’t easily aroused. Patients in deep sedation may experience complete or partial loss of reflexes and an inability to maintain a patent airway independently.

Deep sedation has been successfully effective in 97.8% of patients during endoscopy, dental, and surgery procedures. However, this does not mean that it does not have inherent risks or adverse effects, as evidenced by the remaining 2.2%. Let’s dive in and understand the potential downsides.

Deep Sedation: Adverse Effects

Deep sedation is generally safe, even for patients with certain health concerns or comorbidities. However, like other medical techniques, it can have adverse effects, which may include respiratory complications, delayed emergence, and postprocedural disorientation.

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Potential Respiratory Complications

Respiratory complications are primarily tied to the sedative drugs used, which have been known to suppress the central nervous system depending on the dosage. The greater the dosage of sedatives, the greater the degree of respiratory complications.

Some of the well-documented respiratory complications arising from the use of deep sedation include oxygen desaturation, hypoventilation, reduced respiratory rate, and respiratory depression or arrest. The latter occurs when airway patency is compromised.

Respiratory depression, which increases when a combination or large dose of sedative drugs is used, presents as a decreasing rate and depth of ventilation. This complication arises due to the depression of respiratory control centers, which usually trigger breathing when they sense increased levels of CO² in the blood. All known sedatives have the potential to depress these respiratory control centers, but this is a manageable problem with proper monitoring and the right dosages.

Delayed Emergence From Sedation or Prolonged Recovery

When we talk about procedures requiring deep sedation, another term that crawls up often is emergence. This refers to the gradual gaining of consciousness once the administration of anesthesia has stopped. For most patients, this transition is smooth and flawless. For others, emergence may be delayed, prolonging the recovery process. When this happens, patients may take a long time to regain their cognitive functions, increasing the risk of cognitive impairment.

Patients need to have a steady emergence to be transported out of the OR and into the PACU. Normally, patients should be fully conscious and 100% cognitively capable within ~60 minutes of their last dose of sedatives. However, this duration may vary depending on the dosage and type of medical procedure.

Post-procedural Disorientation or Delirium

Patients who take too long to emerge from deep sedation may experience cognitive dysfunction, abnormal sleep patterns (sleep deprivation), and eventually delirium. Delirium is described as an acute alteration in a person’s cognitive functions. It is characterized by, among other things, thought disorganization and erratic consciousness.

Patients coming out of the OR where anesthesia was administered do require restorative sleep for normal and quick recovery. However, as pointed out, deep sedation may have the undesirable impact of causing abnormal sleep patterns which may deny patients the much-needed restorative sleep.

As common as it may be among patients in the ICU, sleep deprivation is a known risk factor for delirium and prolonged mechanical ventilation. Both of these have been linked to ICU overstay as well as ICU mortality rates. Older patients are at more risk of suffering from delirium, as well as those with a history of drug abuse.

Potential Risks Associated with Deep Sedation

Many complications may occur in the post-anesthesia care unit (PACU). According to the statistics, the three most prevalent complications in the PACU are airway events, hemodynamic instability, and postoperative nausea and vomiting.

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Risk of Overdose

Deep sedation is a delicate and precise technique that requires physicians to be highly experienced and follow the sedation guidelines and dosage strictly. This is why a deep sedation course becomes mandatory for any medical professional specializing in anesthesia administration.

Risk of Hemodynamic Instability

Another risk that physicians should aim to avoid when administering deep sedation is hemodynamic instability. Incidences of hemodynamic instability, especially in post-anesthesia care units, are quite common due to the erratic heartbeat, blood pressure, and cardiac output caused by deep sedation.

Independently, this risk factor has been attributed to long-term patient morbidity as well as prolonged post-care hospital stay. If left untreated, hemodynamic instability can lead to myocardial ischemia, cerebrovascular accident, hemorrhage, and even heart failure.

Risk of Cardiovascular Depression

Cardiovascular depression is another major risk associated with deep sedation. In dental procedures, it may be characterized by fainting or vasovagal syncope — a cardiovascular complication attributed to inadequate oxygen delivery to the brain.

In other procedures involving deep sedation, the risk of cardiovascular complications is a cause of abnormalities in heart rate and blood pressure. These can lead to hypotension and bradycardia.

Hypotension as a risk of deep sedation is usually a result of depressed sympathetic outflow. It becomes a serious concern because the resultant low diastolic blood flow decreases the rate of coronary blood flow. If left unmanaged, hypotension can escalate into reflex tachycardia, which results in an increased demand for myocardial oxygen.

Complications in Patients with Special Healthcare Needs

Patients with special needs provide a challenge to physicians administering deep sedation. This, therefore, requires specialized training and certification to effectively administer sedation medication to patients with special needs — those who are elderly, expectant, or have comorbidities.

Elderly persons are at higher risk of developing cardiovascular, respiratory, delayed emergence, and post-procedural delirium complications more than any other patient group.

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Pregnant women are at risk of low birth weight, as reported in several studies. Patients with comorbidities such as allergic reactions to anesthesia, diabetes, or heart disease are also at a high risk of developing most of the complications associated with deep sedation.

Pregnant women are recommended to wait until the second trimester before they undergo any sedation. If the procedure cannot wait, then the decision to proceed with sedation should be made by a multidisciplinary team of anaesthesiologists, obstetricians, surgeons, and perinatologists.

Conclusion

When administering deep sedation, physicians should educate patients about the potential adverse effects such as respiratory complications, delayed emergence, and post-procedural delirium. What’s more, measures ought to be well laid out and put in place to prevent, counter, or mitigate inherent risks, such as overdose, hemodynamic instability, and cardiovascular depression, among other risks associated with deep sedation that could present dangers to patients with special needs.