7.7Postoperative Nausea and Vomiting (PONV)

Macario’s study [3] elegantly showed that fear of PONV is the primary concern of patients. The hallmark of a successful office-based practice resides in the combined efforts of the anesthesiologist and surgeon to eliminate this outcome. Friedberg [31] elegantly showed that using a non-opioid propofol/ ketamine technique, the incidence of PONV can be an exceptional, 0.5%.

7.7.1 Risk Factors

A number of studies, including Apfel’s [32], highlight the main risk factors: (1) female, (2) young, (3) nonsmoker, (4) previous history of PONV and or motion sickness, (5) emetogenic procedure (gynecology, laparoscopic, strabismus, facial surgery, (6) duration 2 h or more, (7) opioid exposure, and (8) volatile anesthetic used.

The preoperative assessment, usually a phone call the day before surgery, is vital in determining the patient’s relative risk of PONV and goes a long way to providing reassurance that this issue will be addressed.

Guided by the work of Scuderi and White [33], patients assessed as high risk may benefit by receiving multimodal antiemetic therapy. This focuses on the use of small doses of differing classes of antiemetics so as to target the emesis pathway at different points. Numerous cocktails abound but one which the author has found useful incorporates: droperidol (0.625 mg), dexamethasone 8 mg, given after induction, then granisteron (0.5–1.0 mg) at the conclusion of the procedure.

7.8 Techniques of Sedation

The author has tried all manners of drug combinations with propofol: midazolam, fentanyl, remifentanil, but settled on a simpler non-opioid propofol TCI/midazolam technique.

Deference to such luminaries as Friedberg et al. [34], who have mastered Propofol-Ketamine/BIS/ Monitored Anesthetic Care, producing spectacular results, in particular PONV <1%.

In the resource constrained environment in which the author works, sadly, BIS is not readily available, so ketamine is not routinely used. Traditional teaching may question the use of BIS in spontaneously breathing patients, citing the prime validation for BIS coming from the at-risk paralyzed adult surgical population [16]. Infusing propofol by means of tar- get-controlled plasma or effect site concentration counters the interindividual variability in the way propofol is hydrolyzed in the liver [35]. Admittedly, by not using BIS, the ability to distinguish movement as being spinal cord or brain generated is lost. Usually a further injection of local solves the problem; after all the guiding tenet of the whole technique is reliant upon the surgeon providing adequate local analgesia.

The author’s reluctance to use ketamine without BIS resides in not knowing that a stable hypnotic level of propofol has been achieved. On the downside, ketamine’s effect though relatively short lived, can produce significant cerebral excitation with a concomitant increase in blood pressure and bleeding. Often, this excitation can progress to agitation manifest by additional movement within the surgical field. Table 7.5 outlines the technique.

Table 7.5 Propofol target-controlled infusion (TCI) – Midazolam technique

Clonidine 200 mcg po, 30–60 min prior to surgery (defer if sys BP < 100 mmHg)

Anesthetic room

ss Monitoring: EKG, NIBP, SpO2

ss Intravenous line with appropriate non-return valve

ss Midazolam 2–3 mg, Glycopyrrolate 200 mcg

ss Supplemental oxygen: 2 l/min via nasal prongs

Operating room

ssPropofol TCI: start with plasma conc (Cp = 2.0 mcg/ml) stepwise increments of 0.5 mcg/ml till stable breathing pattern emerges

ssBefore injection of local anesthesia: bolus = 1.0–1.5 mcg/ ml expect some movement

ss Basal Cp = 2.5–3.5 mcg/ml

Prophylactic antibiotics, antiemetics (if high risk), Dexamethasone = 8 mg

Acetaminophen 1 g (intravenously 20 min before end procedure)

Levobupivacaine 0.25% to field (topical or via drains)

7.9 Conclusions

A successful office-based practice is reliant on Propofol Intravenous Anesthesia, avoidance of opioids, minimal airway intervention and enlightened use of local analgesia. Undoubtedly, level-of-consciousness monitoring provides further assurance, making the use of ketamine a more realistic proposition however, with vigilance and attention to detail, a simple and safe technique, as described does afford excellent outcomes for all concerned.

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