Suitable office-based procedures range from incision and drainage of abscesses to microlaparoscopies. Very few data are available regarding procedure length and suitability for office-based procedures, but it has been recommended that procedures not exceed 6 hours in duration and be completed by 1,500 hours to allow for recovery time. In addition, when determining the suitability of a procedure, one must consider the possibility of hypothermia, blood loss, and significant fluid shifts.

1. Specific Procedures
   1. Liposuction is the most commonly performed plastic surgery procedure and is accomplished by placing hollow rods into small incisions in the skin and suctioning subcutaneous fat into an aspiration canister.
      1. Superwet and tumescent techniques use large volumes (1–4 mL) of infiltrate solution that consists of 0.9% saline or Ringer's lactate with epinephrine 1:1,000,000 and lidocaine 0.025% to 0.1%. Blood loss is generally 1% of the aspirate with these techniques. The peak serum levels of lidocaine occur 12 to 14 hours after injection.
      2. Liposuction is not a benign procedure and may be associated with morbidity and mortality caused by pulmonary embolism, anesthesia, myocardial infarction, infection, and hemorrhage.
      3. Risk factors include the use of multiliter wetting solution infiltrations, large-volume aspiration causing massive third spacing, multiple concurrent procedures, anesthetic sedative effects yielding hypoventilation, and permissive discharge policies.
   2. Aesthetics. Many facial aesthetic procedures, such as blepharoplasty, rhinoplasty, and meloplasty, are routinely performed in the office setting, usually under varying depths of monitored anesthesia care (MAC) but occasionally under general anesthesia.
      1. Facial plastic procedures that require the use of a laser pose a problem for the use of supplemental nasal oxygen to maintain adequate SpO₂. Any supplemental oxygen must be turned off during periods of laser or electrocautery use about the face.
      2. The avoidance of supplemental oxygen when medically appropriate is ideal.
   3. Breast. Procedures such as breast biopsy or augmentation, implant exchanges, and completion of transverse rectus abdominal muscle flaps may be performed in office settings. It is likely that patients undergoing breast surgery will require antiemetic medication and postoperative analgesics.
   4. Gastrointestinal endoscopy includes esophageal, gastric, and duodenal endoscopies and colonoscopies. This patient population tends to be older, with significant comorbid conditions. Insertion of the endoscope can usually be accomplished with sedation using small doses of propofol with or without midazolam.
      1. Colonoscopy is painful secondary to the insertion and manipulation of the endoscope and may be associated with cardiovascular effects, including dysrhythmias, bradycardia, hypotension, hypertension, myocardial infarction, and death.
      2. The gastroenterology community has sought to be able to provide moderate or even deep sedation with propofol without the assistance of an anesthesia professional. (Propofol's package insert states that it may only be administered by individuals who are trained in the administration of drugs that cause deep sedation and general anesthesia.)
   5. Dentistry and Oral and Maxillofacial Surgery. Nitrous oxide has been used for most of the world's office-based dental anesthetics since 1884, when Horace Wells, himself a dentist, had nitrous oxide administered for a wisdom tooth extraction by a colleague. A high level of safety is attributed to the use of pulse oximetry, blood pressure, and ventilation monitoring, as well as administration of supplemental oxygen.
   6. Orthopedics and Podiatry. The orthopedic office provides an excellent location for an anesthesiologist who practices regional anesthesia (intra-articular local anesthesia and MAC, three-in-one block of the lumbar plexus, brachial plexus block, ankle block). Spinal anesthetics in the office-based setting must be of short duration. Lidocaine, which provides reliable short-acting analgesia, may be associated with an increased risk of transient neurologic symptoms in the ambulatory patient population.
   7. Gynecology and Genitourinary. Many procedures, such as dilation and curettage, vasectomy, and cystoscopy, have been performed in the office setting for many years, and recently there has been an increase in more invasive procedures such as mini-laparoscopies, ovum retrieval, prostate biopsies, and lithotripsy, necessitating an anesthesiologist's expertise.
   8. Ophthalmology and Otolaryngology. Topical anesthesia or periorbital and retrobulbar blocks are frequently used to provide analgesia. Supplemental sedation may be required.
   9. Pediatrics. Although no minimum age requirement for a child to undergo an office-based anesthetic has been established, patients older than 6 months of age and with an ASA physical status of 1 or 2 may be reasonable candidates for OBA (dental surgery, lacrimal duct probing, myringotomy) (Table 31-9: Guidelines for the Pediatric Perioperative Anesthesia Environment).

Office-Based Anesthesia

1. Brief Historical Perspective of Office-Based Anesthesia
2. Advantages and Disadvantages
3. Office Safety
4. Patient Selection
5. Surgeon Selection
6. Office Selection and Requirements
7. Procedure Selection
8. Anesthetic Techniques
9. Postanesthesia Care Unit (PACU)
10. Regulations
11. Business and Legal Aspects
12. Conclusions