The era of ambulatory anesthesia started around 1970. In the pioneering years, almost all the patients were American Society of Anesthesiology (ASA) 1 or 2 status. Ambulatory surgery gained rapid popularity, and the number of ambulatory surgery centers has increased tenfold in the last 30 years and the growth is continuing. In many countries, the goal is to have more than 60% of surgical procedures performed on an ambulatory basis. This section of ambulatory anesthesia tries to focus on several issues which are still debated and need some highlights
Due to the rapid growth of ambulatory anesthesia, ASA 3 patients with several comorbidities and even ASA 4 patients are treated in ambulatory centers. Michael Walsh (pp. 659–666) addresses this issue. Frailty which can be defined as ‘decreased physiologic reserves’ is an important concept to evaluate the risk and outcomes. It seems important to evaluate the frail patients, as frail patients show a significant increased the rate of same-day cancellation and the risk of complications even for common ambulatory procedures. However, identification of frail patients remains time consuming and labor intensive. Moreover, management of high-risk ambulatory patients requires specific management peroperatively and postoperatively.
To improve the delivery of care in the perioperative period, neuromonitoring including monitoring of depth of anesthesia and tissue/brain oxygenation (SbO2) can be routinely used. On the contrary, Goldstein et al. (pp. 667–672) highlight the lack of well designed clinical trials demonstrating that the routine use of neuromonitors in an ambulatory setting can induce cost savings of a decrease in morbidity and mortality. The authors consider that it is actually difficult to conclude that processed electroencephalogram (EEG) should be routine in all cases, but its uses remain strongly recommendable: total intravenous anesthesia when neuromuscular blocking agents are used, as there is a significant increase in the incidence of awareness with recall in these cases. Selective use could also be useful in the elderly to titrate anesthetic agents and avoid drug overdose. On the other hand, up to now, there is no evidence for the authors that the routine use of cerebral oximetry even in patients at risk (shoulder surgery, cervical spine surgery) is beneficial.
Although there are not many anesthetic drugs currently under investigation, Barends et al. (pp. 673–678) present the results of ongoing research to find the ideal presentation of sedative. Continuous administration of propofol, including target-controlled infusion, is widely used particularly in Europe in ambulatory surgery as it offers several advantages such as amiability, predicted recovery and less nausea and vomiting. One of the main issues is the choice of the pharmacokinetic model to improve accuracy of propofol predicted concentration. A new model developed by Eleveld et al. including age, weight, height, sex and presence or absence of concomitant anesthetic drugs. The model could be useful in clinical practice, as predicted propofol concentrations using this model match well with recommendations for all age groups for both anesthesia and sedation. The use of ketamine for procedural sedation remains discussed. Although the use of ketofol, a mixture of propofol ans (es-) ketamine, has been proposed for sedation, Barends et al. insist on the lack of scientific evidence about its advantages in clinical practice. Although dexmedetomidine, an alpha-2 agonist, is now available for procedural sedation in Europe, its use is limited by cardiovascular effects, mainly because hypotension could last for several hours after cessation of infusion. Therefore, there is a need for a new pharmacokinetic/pharmacodynamic (PKPD) model which may allow better control of dexmedetomidine administration targeting optimal sedation. The only new drug under current investigation is a benzodiazepine: remimazolam.
Rebound pain is becoming a major issue as it can delay discharge of the patient. Patricia Lavand’homme (pp.679–684) publishes an interesting review on this controversial issue. By definition, rebound pain is a very severe pain appearing when peripheral nerve block wears off, usually it does not respond to intravenous opioids administration. Although there is a lack of large prospective studies, it postoperative incidence could reach 40%. The prevention of such a complication remains controversial. However, the use of oral multimodal analgesics before the peripheral nerve block wears off could be one of the answers; education of the patient to prevent or minimize its occurrence could also be of importance. As pointed by the author, in 2018, rebound pain represents a challenge as an opportunity to improve quality of ambulatory anesthesia. Another response could be the development of new opioids drugs delivery. Iskander and Gan (pp. 685–692) present in this issue some fascinating new methods of drug delivery which could be valuable in the ambulatory setting. Nanoparticles and depot delivery system technologies could be used to control the release and thereby increase the specificity and duration of action of local anesthetics. These new formulations could improve postoperative analgesia with less toxicity and prevent in some case rebound pain. Several techniques for delivery of local anesthetics including liposomal bupivacaine, SABER-bupivacaine, bupivacaine in a collagen matrix and HTX-011, a mixture of bupivacaine and meloxicam are currently under investigation. Tapentadol belongs to a new class of μ-receptor agonist that acts synergistically at the μ-opioid receptor and noradrenaline reuptake inhibitor. First studies in humans have shown that it could provide efficient analgesia with a reduced rate of nausea and vomiting. Oliceridine acts at the μ-receptor via preferential G-protein pathway, a mechanism of action that could avoid side effects. Its main interest would be the reduction of side effects such as nausea, vomiting but also respiratory depression. As suggested, alternate routes of administration, including sufentanil microtablets, could be an interesting option as it does not rely on intravenous access and has the potential to prevent issues related to abuse and overdose which remain a major health problem in USA.
The prevalence of obesity continues to rise worldwide. Mark Skues (pp. 693–699) highlight the need for mandatory multidisciplinary preoperative assessment when ambulatory surgery is planned for obese patients. Moreover, additional specific equipment are required both in the ward and operating theater. Obstructive sleep apnea (OSA) disorder can be a major problem, not only in obese patients, when ambulatory surgery is needed. This issue is addressed by Nagappa et al. (pp. 700–706)They recommend using a screening tool for OSA as part of mandatory preoperative evaluation to stratify patients at risk. The authors highlight the bidirectional relationship between OSA and difficult airway which contributes to a high rate of adverse respiratory events. Chronic intermittent hypoxia and sleep fragmentation in obese patients may cause upregulation of μ opioid receptors which results in increased sensitivity and hyperalgesia. Therefore, postoperative continuous monitory is strongly recommended for high-risk OSA patients receiving opioids. Of course, regional anesthesia is an interesting option for these patients, and several publications demonstrate that neuraxial anesthesia or peripheral nerve block is associated with decreased risk of respiratory complications.
Finally, Young et al. (pp. 707–712) make a focus on the rate of complications in the office-based surgical (OBS) settings. The majority of procedures include plastic surgery with a few reports on vascular and dental surgery. There is still a lack of large multicenter studies; however, the rate of recently published complications in OBS appears to be similar or better than previously published studies. It is likely that there is an effect of procedure location. This could be explained by the presence of an anesthesiologist in the setting, the available monitors or the number of procedures.
In conclusion, this edition of Current Opinion in Anesthesiology shows that there have been several improvements over the last 10 years, but there is still some room for quality improvement and optimization of the ambulatory pathway.
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