**7. Pitfalls to avoid**

Anytime the words propofol and ketamine are used, readers too often think ketofol, the admixture of the two agents in the same syringe [22]. There are many permutations of the ideal ratio of propofol to ketamine. Mixing the two agents makes it very difficult, if not impossible, to differentiate when adequate hypnosis occurs as well as when midbrain NMDA receptor saturation occurs. "Goldilocks" anesthesia provides numerically reproducible propofol levels to define adequate hypnosis as well as the absence of EMG spikes with local anesthesia injection to define midbrain NMDA receptor saturation (**Table 5**).

Propofol ketamine is like the martini cocktail wherein the propofol is the 'vodka' and the ketamine is the 'olive.' Ketofol is when the propofol in mixed with the ketamine. These are two very different approaches that should never be confused with one another. **Do not mix propofol with ketamine.**

Propofol hypnosis is protective of ketamine hallucinations [13]. **Do not give ketamine before propofol hypnosis.** Bolus propofol induction will not provide a stable CNS propofol level to protect against ketamine hallucinations. Do not induce with 1–2 mg/kg propofol boluses.

Propofol at BIS < 75 with baseline EMG is a numerically reproducible protection against ketamine hallucinations. **Do not give ketamine if BIS > 75 or EMG is not at baseline.**

**Adequate local analgesia is critical** to minimizing or eliminating the need for postoperative opioid pain rescue. Do not fail to have the surgeon reinject the immediate area of dissection when patient movement occurs *without* EMG spike and BIS < 75. More propofol or ketamine is an inadequate response for patient movement at BIS < 75 with baseline EMG. Adding opioids instead of more local analgesia is not only inadequate to correctly deal with insufficient local analgesia but also increases the probability of PONV.

Aggregate ketamine doses >200 mg is associated with prolonged emergence. **Do not exceed 200 mg ketamine or give ketamine in the last 20 minutes** of the case or use ketamine in cases less than 20 minutes. Spontaneous ventilation is a prized safety feature of "Goldilocks" anesthesia. **Do not introduce an MH trigger like SCH to treat laryngospasm.** Because of the

Do not give ketamine before propofol.

Do not bolus propofol for induction. Incrementally induce.

Do not give ketamine at BIS > 75.

Only after the patient's propofol level has stabilized should the 50 mg ketamine, **independent of body weight**, be given, **3 minutes prior** to local analgesia injection. Any patient movement accompanied with an EMG spike during injection must be given more propofol to drive the EMG spike back to the baseline. As little as repeated 100 mcg/kg propofol boluses or as much as 200–400 mcg/kg propofol boluses may be required. An upward basal rate should be consid-

The surgeon should inject as much of the proposed surgical field(s) with the initial ketamine dose whenever possible. Review of 1000 patient records demonstrated 80% were performed with one or two 50 mg ketamine doses. **Aggregate ketamine doses greater than 200 mg were associated with prolonged emergence**. Many surgeons are concerned that the lidocaine or epinephrine effect will not last if a lengthy procedure is contemplated. Long experience with Klein's ultradilute solution [21] has shown that concern is unwarranted even in 6-hour cases. Ketamine is to facilitate a painless injection of **'virgin' surgical fields** and is not necessary for

The traditional crowing sound of incompletely closed vocal cords is rarely seen with "Goldilocks" anesthesia. The type of laryngospasm is characterized by complete vocal cord closure. The only prodrome is a cough or a sneeze. The **traditional remedies** of anterior jaw thrust and positive pressure ventilation are **ineffective** in dealing with ketamine-associated laryngospasm. The author has consistently been successful treating this type of laryngospasm with IV lidocaine 1 mg/lb or 2 mg/kg given STAT whenever a cough or sneeze is observed.

Spontaneous ventilation preservation is a hallmark of successful "Goldilocks" anesthesia. The use of succinylcholine (SCh) will produce a patient with very painful postoperative muscle pains. SCh is not recommended as it is an MH trigger as opposed to nontriggering propofol or ketamine. Nondepolarizing rocuronium in small doses is a possibility but also defeats the value of spontaneous ventilation even with its short duration of action. Propofol elevates the lidocaine seizure threshold. The author has not observed lidocaine-induced seizures when treating laryngospasm with IV lidocaine. However, in *extremely* rare cases, severe bradycardia, even asystole, may be seen with multiple IV lidocaine injections. Preemptive lidocaine should be considered optional. Consider deepening propofol level after 2–3 lidocaine doses

Anytime the words propofol and ketamine are used, readers too often think ketofol, the admixture of the two agents in the same syringe [22]. There are many permutations of the ideal ratio of propofol to ketamine. Mixing the two agents makes it very difficult, if not impossible, to differentiate when adequate hypnosis occurs as well as when midbrain NMDA receptor

ered to maintain the patient's propofol level at 60 < BIS < 75 *with* baseline EMG.

reinjections when needed.

50 Anesthesia Topics for Plastic and Reconstructive Surgery

are required to break the laryngospasm.

**7. Pitfalls to avoid**

**6. Laryngospasm**

Do not fail to provide adequate local analgesia.

Do not give opioids in lieu of adequate local analgesia.

Do not give ketamine in lieu of adequate local analgesia.

Do not exceed an aggregate ketamine dose >200 mg.

Do not give ketamine in the last 20 minutes of a case or for cases <20 minutes duration.

Do not paralyze instead of using lidocaine to break laryngospasm.

Do not use succinylcholine instead of lidocaine to treat laryngospasm.

**Table 5.** Pitfalls to avoid.

Do not mix propofol and ketamine. Titrate separately to define goals of adequate hypnosis and midbrain NMDA saturation.

subsequent need to support ventilation, rocuronium is not preferred over IV lidocaine even though postoperative muscle pain will not result from its use.

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