Nancy Staats
INTRODUCTION
There are a wide range of procedures being performed—from epidural steroid injections to implantation of spinal cord stimulators. Different procedures may require different levels of and different sedation techniques in order to optimize the outcome and the experience for the patient. Some proponents of using an anesthesiologist for sedation point to an appropriate analgesic experience for the patient, lack of movement, and safety in the operating room. Others are less inclined to utilize an anesthesiologist, citing risk of overuse of sedative medications, sometimes even resulting in spinal cord injury with deep sedation, along with an increased cost of care. When appropriately used, sedation can make the experience safer, more effective, efficient, and more comfortable without jeopardizing patient safety. Clearly if sedation is utilized, it is important to follow safe guidelines. There remain some principles that should be followed in providing sedation when performing interventional procedures.
TYPES OF ANESTHESIA
PREOPERATIVE ASSESSMENT
As with any patient undergoing anesthesia of any kind, patients need an appropriate preoperative assessment, including risk level. While many of the procedures performed by the interventional pain physician may be considered minor, it is important to consider preoperative risk factors. Sicker patients have increased risk, even for a minor procedure. Complete preoperative assessment guidelines are readily available elsewhere they include but are not limited to:
Contrast (possible co-reaction with allergy to shellfish)
Antibiotics
Allergies to anesthetics, egg whites, sulfites
Latex
RELEVANT FACTORS SPECIFIC TO THE CHRONIC PAIN PATIENT
PREOPERATIVE ANTICOAGULANTS
Chronic or acute use of medications that interfere with coagulation—though controversy exists, in general the patient taking NSAIDs or other classes of anti-inflammatory agents, including aspirin, are at low risk. For certain larger procedures, however, a PFA (platelet function assay) may be warranted. Warfarin should be stopped 4 to 5 days before the spinal procedures, and check INR and/or PT/PTT on the day of procedure. For more details, refer to anticoagulation chapter in this book. Weigh risks of stopping the anticoagulants to risks of epidural and/or spinal hematoma. The important factor is communication between the patient, surgeon and the anesthesiologist to decide the appropriate preoperative tests in order to minimize late cancellations.
MULTIPLE ALLERGIES
Multiple allergies (it’s important to inquire about “true” allergies). True allergy to local anesthetics, and particularly the amide local anesthetics, is extremely
Follow the NPO guidelines appropriately and optimally. Our policy is NPO for 8 hours for solids and 4 hours for clear liquids; sips of water or other clear liquid up to 2 hours before is permitted. However, it is anesthesiologist’s responsibility to individualize the anesthetic plan for safety and efficiency.
REALISTIC EXPECTATIONS
Sometimes, the patient states “just put me out, I don’t want to feel a thing!” One must take the time to educate the patient regarding the reasons for the procedure and why their input may be critical to its safety and success. Furthermore, having realistic expectations makes it easier for everyone, and the vast majority of patients will understand when it is explained to them. The patient provides valuable feedback, whether negative (intraneural or intravascular placement) or positive (stimulator in the correct place). Many patients are comforted knowing that they will have someone with them for the entiretime, making sure they are safe, stable, and as comfortable as possible.
DIAGNOSTIC BLOCKS
When performing diagnostic procedures, it is best to avoid opioid analgesics as they can alter the response to the diagnostic test. Diagnostic medial branch facet injections, discography, and diagnostic sympathetic blocks are common examples of such diagnostic procedures. After each block, the interventional pain physician will want to understand the response to the block. For example, if a patient has excellent relief with a medial branch block under most circumstances that may lead to performance of a radio frequency (RF) ablation. For example, if a patient received fentanyl prior to the injection or during the injection, the response is unreliable and may lead to ineffective RF ablation.
INTRAOPERATIVE CARE
Similar to any patient undergoing sedation, the pain patient undergoing an interventional procedure requires continuous monitoring of oxygen saturation, blood pressure, electrocardiogram, and respiratory rate throughout (see Table 11-1). We often give an anxiolytic agent like midazolam immediately upon entering the OR, prior to final positioning. We then explain everything and sedate with propofol to achieve an appropriate level of sedation for the procedure. Opioids may be needed in patients in significant pain prior to the procedure, although they need to be avoided during any diagnostic blocks. It is very important not to over-sedate patients undergoing a cervical block near the spinal cord.
TABLE 11-1. Table of Typical Agents Used for Sedation
POST ANESTHETIC CARE
As with any patient after receiving sedation, patients require appropriate postoperative care. Our policy is the patient cannot drive, use alcohol or sedatives for approximately 24 hours (or at least until the next day, whichever is less) after anesthesia. When light sedation is used prior to diagnostic neural blockade, patients should be monitored after the procedure. Patient should not be discharged without an escort.
Suggested Reading
Manchikanti. Pain Physician. 2011 Jul-Aug;14(4):317-329.
Horlocker TT, Neal JM, Rathmell JP, Reg Anesth Pain Med. 2011 Jan-Feb;36(1):1-3.
Baluga JC. Allergol Immunol. 2002 Jan-Feb;30(1):14-19.
Fuzier R. Pharmacoepidemiolog Drug Saf. 2009 Jul;18(7): 595-601.
Murphy A. Anesth Analg. 2011 Jul;113(1):140-144.
Dewachter P. Curr Opin Anesthesiol. 2011 Jun;24(3):320-325.