Awareness and Dreaming During Total Intravenous Anesthesia in Outpatients Undergoing Extracorporeal Shockwave Lithotripsy

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  • Topic: Anesthesia, Anesthesia awareness, General anaesthesia
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  • Published : June 19, 2011
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NATIONAL KIDNEY AND TRANSPLANT INSTITUTE
Department of Anesthesiology

TITLE: AWARENESS AND DREAMING DURING
TOTAL INTRAVENOUS ANESTHESIA IN OUTPATIENTS UNDERGOING
EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY:
A PRELIMINARY SURVEY

AUTHOR:Xenia P. David, M.D.
Senior Resident

CO-INVESTIGATORS:Alexander Bautista, M.D.
Junior Resident

Warren Caballa, M.D.
Junior Resident

Ronald Torres, M.D.
Junior Resident

SUPERVISING INVESTIGATOR:Arnold S. Uy, M.D., D.P.B.A.
Consultant
NKTI, Department of Anesthesiology

ENDORSED BY:Jaime G. Velasquez, M.D., D.P.B.A
Chairman
NKTI, Department of Anesthesiology

SPECIALTY/SUBJECT MATTER/CATEGORY OF STUDY: Anesthesia

PRIMARY LOCATION OF THE STUDY: National Kidney and Transplant Institute

FUNDING/SPONSORING AGENCY: National Kidney and Transplant Institute

SUMMARY

The incidence of awareness during anesthesia with postoperative recall is relatively low at 0.13%. However, this may result in posttraumatic stress disorder in the patient, and have in some instances have given rise to litigation. Intraoperative awareness is now a well-recognized complication, and preventing it is one of the anesthesiologist’s top priorities.

The risk of awareness is associated with the use of neuromuscular relaxants, nitrous oxide, and intentionally light anesthesia for cardiac surgeries and emergency operations in trauma patients. Total intravenous anesthesia using the popular anesthetic agent propofol may also result in awareness due to the wide interpatient variability in dosage; the inability to monitor the plasma concentrations of the drug, unlike in inhalational anesthetics; and the agent’s lack of amnestic properties. A large number of patients at this institution undergo propofol anesthesia for extracorporeal shockwave lithotripsy (ESWL), so the potential for awareness during this procedure must not be overlooked.

This preliminary prospective study aimed to determine the incidence of intraprocedural awareness and postprocedural recall in patients undergoing ESWL at the National Kidney and Transplant Institute.

RATIONALE/SIGNIFICANCE OF THE STUDY

The study can provide the background for either maintaining or improving the current anesthetic management provided for patients undergoing ESWL. A high incidence of awareness can indicate the emphasis on the use of other anesthetic agents, or the implementation of a monitoring system for patient awareness.

DEFINITION OF TERMS

Consciousness: a state in which a patient is cognizant of his or her surroundings.[i]

Anesthesia awareness - occurs under general anesthesia when a patient becomes cognizant of some or all events during surgery or a procedure, and has direct recall of those events[ii]

Explicit recall – recall of specific events; conscious memory [iii]

Implicit recall – no recall of specific events but patient’s behavior is modified by memories formed during unconsciousness; unconscious memory [iv]

Dreaming during anesthesia – any recalled experience (excluding awareness) which occurred between induction of anesthesia and the first moment of consciousness upon emergence[v]

REVIEW OF RELATED LITERATURE

Awareness is correlative with consciousness, which goes counter to the concept that anesthesia should induce unconsciousness in the patient.[vi] [vii] It is imperative that any memory of wakefulness be suppressed at the end of the operation.

Incidence of Intraoperative Awareness

Awareness is as old as anesthesia itself. During William Morton’s first demonstration of ether anesthesia, the patient later recalled being awake during the procedure.[viii]

The incidence of awareness in patients undergoing anesthesia is 0.1 to 1.0%, with varying figures from Australia (0.10% in 2000), Sweden (0.16% in 2000), the United States (0.13% in 2003), Thailand (0.08% in 2005), and Spain...
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