Authors: Mashour GA, Hudetz AG.
A very elegant review on the controversy of the precise mechanisms of anesthetic-induced unconsciousness and how levels and contents of consciousness interact to generate subjective experience and what this implies for the mechanisms of anesthetic-induced unconsciousness.
This is a retrospective, single institution study, based in the analysis of more than 70000 procedures. A total of 163 adverse events were reported including 13 cases of cardiac arrest. The analysis shows that propofol anesthesia was associated with more incidence of adverse events than midazolam-fentanyl combined. It might look controversial although several factors still need to be considered.
Another successful application of dexmedetomidine as a sedative agent in the clinical setting, in this case for awake craniotomies. Dexmedetomidine exhibits similar efficacy as the combination of propofol and remifentanil but with a significantly less number of respiratory depression related events.
Some years ago a multicenter clinical trial (MENDS) was conducted to evaluate optimal sedation in the critical care setting based on possible effects of the drugs used on patient’s outcomes. They concluded that dexmedetomidine was superior to benzodiacepines in several aspects like length of ICU stay or duration of mechanical ventilation amongst others (Pandharipande PP, JAMA 2007). The present manuscript reports how three different sedation agents, benzodiacepines, propofol or dexmedetomidine, might impact patient outcomes on a sample of more than 9000 episodes of mechanical ventilation in the ICU. Even though the three arms of the study (benzodiazepine, propofol and dexmedetomidine) are not equally represented, with significantly less number of patients in the dexmedetomidine group it is clear that legth of stay was longer in the benzodiacepine group. Also patients sedated with dexmedetomidne had shorter stay in the ICU than propofol. Further detailed studies should be published comparing propofol and dexmedetomidine.
The present systematic review focuses on an interesting aspect: how to measure the outcomes of clinical trials involving procedural sedation. Out of more than 4000 titles regarding different aspects of procedural sedation the authors read in a detailed and critical manner 245 to learn about the different scoring systems and domain explored. After their thorough review the authors conclude that there is room to improve how clinicians measure sedation and that the best approach to come up with an optimal sedation measurement system, including patient reported outcomes, should be undertaken by multidisciplinary teams.
Morbidly obese patients have been increasing its presence in the operating room as patients because of surgical treatment of its condition. These kinds of patients require often critical care and pose several problems related to their management. Sedation technique is one of the aspects that should be considered because of characteristics. The recommended review points out some important points that should be taken care of when dealing with morbidly obese patients in the critical care setting.
The work presented by Borrat et al wants to define safe sedation and analgesia guidelines in this case for upper gastrointestinal endoscopy. One of the most stressful moments for the patient is introduction of the endoscopy tube through the mouth and pharynx. Using a sequential statistical approach the concetrations associated with a probability of 0.5 or 0.9 of avoding gag response are estimated and could be used as a starting point for any combination of sedation and analgesia in this situation.
Optogenetics has transformed research in the understanding on how neural circuits work. The ability to estimulate single neurons enables the investigators to learn how can influence a predetermined behavior or response. In the present paper Luis de Lecea and his research group proposes a framework to investigate all the circuitry involved in the sleep-wake transitions using the stimulation of single neurons. It is through the knowledge of these mechanisms that we might be able to know how similar or different sedation techniques could be as compared to physiologic sleep and to test if the use of specific drugs to induce sedation might have the same beneficial effects as physiologic sleep.
The authors perform a meta-analysis to explore the safety of sedation provided by anesthesiologists or non-anesthesiologists to patients undergoing gastrointestinal endoscopic procedures. No differences were detected between the incidence of desaturation or in the need of airway intervention between both groups. Satisfaction of gastroenterologists and patients was in favor of anesthesiologists. Important limitations like no control for hemodynamics or other aspects like recovery could be studied based on the data collected. Their conclusions might raise some debate in a topic that is controversial by nature.
Dexmedetomidine activates mechanisms of similar nature to those activated for natural sleep induction after sleep deprivation. Using animal models including those with a selective knockdown of 2A adrenergic receptors of the locus ceruleus, the study demonstrates that to induce its sedative effect dexmedetomidine engages neuronal systems involved in natural sleep pathways, which are different to the mechanisms involved in the induction of general anesthesia.