Opioid free. propofol ketamine for ambulatory surgery: the transition from art to science
Ambulatory surgery patients are expected to be discharged to home following their surgery. The three main problems facing their anesthesiologists are 1) delayed emergence, 2) pain, 3) postoperative nausea and vomiting (PONV). The last two problems are well-recognized causes for unintended hospital admissions after day surgery. Ambulatory discharge is predicated on discharge-ready emergence in about an hour following surgery. When patients take longer to emerge, discharge is delayed, increasing nursing hours and decreasing cost-effectiveness. (Patients’ ride delays, while another frustrating problem, are rarely in the purview of the anesthesiologist.)
The patient’s brain cannot respond to information it does not receive. Failure to saturate critical sub-cortical NMDA receptors pre-local anesthetic injection is a major cause of post-operative pain. (1) Following an incremental propofol induction, 50 mg IV ketamine 2-5 minutes pre-injection provides saturation of those NMDA receptors for about 10-20 minutes while the surgeon injects local analgesia (LA).
From March 26, 1992 to December 26, 1998, the technique was qualitative. Glycopyrrolate 0.2 mg IV was given prior to induction. No infusion pump was used. A micro-drip (i.e. 60 gtts . cc-1) IV set was used. A 50 cc IV bag of normal saline or Ringers Lactate into which 50 cc 10 mg . cc-1 propofol was injected. The final propofol concentration was 5 mg . cc.-1 The initial drip rate approximated the patient’s baseline heart rate and adjusted based on response.
Propofol was titrated to the clinical endpoints of loss of lid reflex (LLR) and loss of verbal response (LVR). Incremental propofol induction preserves the muscles responsible for maintaining a patent airway; i.e. genioglossus, orbicularis oris, masseter & temporalis. More than half the patients required only the rhytidectomy position (i.e. chin extended, head lateral) with or without an IV bag under the shoulders to maintain a patent airway. Typical induction times were 2-3 minutes.
SpO2 was maintained between 92-95% with spontaneous ventilation on room air. Oxygen was available but rarely needed to maintain SpO2. Continuous EKG and NIABP was also monitored. Nasal and oral airways, as well as laryngeal mask airways (LMA) were available. Although anesthesia machines were not available, suction, crash carts and defibrillators were. No patients required endotracheal intubation or cardiopulmonary resuscitation.
The use of ketamine without opioids was the basis for the lowest published PONV rate (0.6%) in an Apfel-defined high-risk (i.e. non-smoking, female, PONV history, emetogenic surgery) patient population without anti-emetics. (2) Opioid postoperative rescue was also absent in this portion of the author’s experience. However, there was no objective evidence with which the author could convince the surgeons to re-inject vasoconstricted fields when patients moved during surgery. Adding additional adjuvant drugs that failed to accurately address the issue of inadequate analgesia prolonged patients’ emergence and discharge.