The Role of GABA Receptor Agonists in Anesthesia and Sedation.

GABA (γ-aminobutyric acid) receptors, of which there are two types, are involved in inhibitory synapses within the central nervous system. The GABAA receptor (GABAAR) has a central role in modern anesthesia and sedation practice, which is evident from the high proportion of agents that target the GABAAR. Many GABAAR agonists are used in anesthesia practice and sedation, including propofol, etomidate, methohexital, thiopental, isoflurane, sevoflurane, and desflurane. There are advantages and disadvantages to each GABAAR agonist currently in clinical use. With increasing knowledge regarding the pharmacology of GABAAR agonists, however, newer sedative agents have been developed which employ 'soft pharmacology', a term used to describe the pharmacology of agents whereby their chemical configuration allows rapid metabolism into inactive metabolites after the desired therapeutic effect(s) has occurred. These newer 'soft' GABAAR agonists may well approach ideal sedative agents, as they can offer well-controlled, titratable activity and ultrashort action. This review provides an overview of the role that GABAAR agonists currently play in sedation and anesthesia, in addition to discussing the future role of novel GABAAR agonists in anesthesia and sedation.

Enhanced recovery after bariatric surgery.

PURPOSE OF REVIEW: Enhanced recovery after surgery (ERAS) methodology has demonstrated consistent benefits in patients undergoing colorectal, urological and thoracic surgeries. Principles of these protocols and their advantages are expected to extend into other surgical specialties such as bariatric surgery. In this review, we summarize the components of ERAS protocols for bariatric surgery and present the evidence on the emerging role of ERAS principles in obese patients. RECENT FINDINGS: Many recent trials have evaluated ERAS protocols for bariatric surgery. Most of these protocols originate from modifications within the individual hospital-based conventional perioperative care strategies. Studies demonstrate that 'ERAS based' care requires evidence-based modifications in all preoperative, intraoperative and postoperative phase. Despite a lack of standardization in protocols at present, benefits such as decreased length of hospital stay, rapid patient turnover, shorter operating room times and lower healthcare costs have been well demonstrated repeatedly. SUMMARY: ERAS for bariatric surgery is in its early phase. Nevertheless, literature supports its role in improving perioperative outcomes compared with conventional care in this scenario. Evidence-based protocols, multidisciplinary teamwork and meticulous audit seem to be the key factors for success in ERAS methodology.

Epidural chloroprocaine bolus in emergency cesarean section-lessons learned from a near mishap.

Administration of a large bolus of epidural chloroprocaine to hasten the spread of anesthesia is an accepted practice during emergency cesarean section. Occasionally, this practice can result in a very high block that can compromise patient's safety. We describe a case of epidural chloroprocaine administration in a 4 point position resulting in a high dermatomal block requiring respiratory assistance. Events surrounding the case are discussed, with a view to warn the reader about the pitfalls of such a practice.

Use of computer-assisted drug therapy outside the operating room.

PURPOSE OF REVIEW: The number of procedures performed in the out-of-operating room setting under sedation has increased many fold in recent years. Sedation techniques aim to achieve rapid patient turnover through the use of short-acting drugs with minimal residual side-effects (mainly propofol and opioids). Even for common procedures, the practice of sedation delivery varies widely among providers. Computer-based sedation models have the potential to assist sedation providers and offer a more consistent and safer sedation experience for patients. RECENT FINDINGS: Target-controlled infusions using propofol and other short-acting opioids for sedation have shown promising results in terms of increasing patient safety and allowing for more rapid wake-up times. Target-controlled infusion systems with real-time patient monitoring can titrate drug doses automatically to maintain optimal depth of sedation. The best recent example of this is the propofol-based Sedasys sedation system. Sedasys redefined individualized sedation by the addition of an automated clinical parameter that monitors depth of sedation. However, because of poor adoption and cost issues, it has been recently withdrawn by the manufacturer. SUMMARY: Present automated drug delivery systems can assist in the provision of sedation for out-of-operating room procedures but cannot substitute for anesthesia providers. Use of the available technology has the potential to improve patient outcomes, decrease provider workload, and have a long-term economic impact on anesthesia care delivery outside of the operating room.

Anesthesia for Advanced Bronchoscopic Procedures: State-of-the-Art Review.

The bronchoscopic procedures have seen a remarkable increase in both numbers and complexity. Although many anesthesia providers have kept pace with the challenge, the practice is varied and frequently suboptimal. Shared airway during bronchoscopy poses unique challenges. The available reviews have tried to address this lacuna; however, these have frequently dealt with the technical aspects of bronchoscopy than anesthetic challenges. The present review provides evidence-based management insights into anesthesia for bronchoscopy-both flexible and rigid. A systematic approach toward pre-procedural evaluation and risk stratification is presented. The possible anatomical and physiological factors that can influence the outcomes are discussed. Pharmacological principles guiding sedation levels and appropriate selection of sedatives form the crux of safe anesthetic management. The newer and safer drugs that can have potential role in anesthesia for bronchoscopy in the near future are discussed. Ventilatory strategies during bronchoscopy for prevention of hypoxia and hypercarbia are emphasized.

Changing trends of hemodynamic monitoring in ICU - from invasive to non-invasive methods: Are we there yet?

Hemodynamic monitoring in the form of invasive arterial, central venous pressure and pulmonary capillary wedge pressure monitoring may be required in seriously ill Intensive care unit patients, in patients undergoing surgeries involving gross hemodynamic changes and in patients undergoing cardiac surgeries. These techniques are considered the gold standards of hemodynamic monitoring but are associated with their inherent risks. A number of non-invasive techniques based on various physical principles are under investigation at present. The goal is to not only avoid the risk of invasive intervention, but also to match the gold standard set by them as far as possible. Techniques based on photoplethysmography, arterial tonometry and pulse transit time analysis have come up for continuous arterial pressure monitoring. Of these the first has been studied most extensively and validated, however it has been shown to be substandard in patients with gross hemodynamic instability. The other two still need further evaluation. While the non-invasive methods for arterial blood pressure monitoring are based on diverse technologies, those for measurement of central venous and pulmonary pressures are mostly based on imaging techniques such as echocardiography, Doppler ultrasound, computed tomography scan and chest X ray. Most of these techniques are based on measurement of the dimensions of the great veins. This makes them operator and observer dependent. However, studies done till now have revealed adequate inter-observer agreement. These techniques are still in their incipience and although initial studies are encouraging, further research is needed on this front.

Aprepitant's prophylactic efficacy in decreasing postoperative nausea and vomiting in morbidly obese patients undergoing bariatric surgery.

BACKGROUND: Postoperative nausea and vomiting is a major cause of patient dissatisfaction towards surgery. For bariatric surgery, increased vomiting/retching is detrimental to surgical anastomosis. The present study evaluated the efficacy of aprepitant (neurokinin-1 inhibitor) as a prophylactic antiemetic in morbidly obese patients for laparoscopic bariatric surgery. METHODS: After institutional review board approval, 125 morbidly obese patients were recruited into this double-blind placebo-controlled trial. On random division, the patients received a tablet of aprepitant (80 mg) in group A, or a similar-appearing placebo in group P, an hour prior to surgery. All patients received intravenous ondansetron (4 mg) intraoperatively. Postoperatively, the patients were evaluated for nausea and vomiting by a blinded evaluator at 30 min, 1, 2, 6, 24, 48, and 72 h. RESULTS: Both groups were evenly distributed for age, body mass index, type, and length of surgery. Cumulative incidence of vomiting at 72 h was significantly lower in group A (3%) compared to group P (15%; p = 0.021). Odds ratio for vomiting in group P compared to group A was 5.47 times. On Kaplan-Meier plot, time to first vomiting was also significantly delayed in group A (p = 0.019). A higher number of patients showed complete absence of nausea or vomiting in group A compared to group P (42.18 vs. 36.67%). On the other hand, nausea scores were unaffected by aprepitant, and no significant difference between groups was found at any of the measured time points. CONCLUSIONS: In morbidly obese patients undergoing laparoscopic bariatric surgery, addition of aprepitant to ondansetron can significantly delay vomiting episodes simultaneously lowering the incidence of postoperative vomiting.

Anesthesia for gastrointestinal endoscopy in patients with left ventricular assist devices: initial experience with 68 procedures.

AIMS AND OBJECTIVES: Continuous flow left ventricular assist devices (LVAD) have emerged as a reliable treatment option for heart failure. Because of bleeding secondary to anticoagulation, these patients present frequently for gastrointestinal (GI) endoscopy. The presently available literature on perioperative management of these patients is extremely limited and is primarily based upon theoretical principles. MATERIALS AND METHODS: Perioperative records of patients with LVAD undergoing (GI) endoscopy between 2008 and 2012 were reviewed. Patient, device and procedure specific information was analyzed. RESULTS: A total of 105 LVADs were implanted, and 68 procedures were performed in 39 patients. The most common indication was GI bleed (48/68), with yearly risk of 8.57% per patient. A total of 63 procedures were performed under deep sedation, with five procedures requiring general anesthesia. Intra-procedure hypotension was managed by fluids and (or) vasopressors/inotropes (phenylephrine, ephedrine or milrinone) guided by plethysmographic waveform, non-invasive blood pressure (NIBP) and LVADs pulsatility index (for HeartMate II)/flow pulsatility (for HeartWare). No patient required invasive monitoring and both NIBP and pulse oximeter could be reliably used for monitoring (and guided management) in all patients due to the presence of native heart's pulsatile output. CONCLUSION: In the presence of residual heart function, with optimal device settings, non-invasive hemodynamic monitoring can be reliably used in these patients while undergoing GI endoscopy under general anesthesia or monitored anesthesia care. Transient hypotensive episodes respond well to fluids/vasopressors without the need of increasing device speed that can be detrimental.

Outpatient endoscopic retrograde cholangiopancreatography: Safety and efficacy of anesthetic management with a natural airway in 653 consecutive procedures.

BACKGROUND: Endoscopic retrograde cholangiopancreatography (ERCP) is a unique diagnostic and therapeutic procedure performed in high risk patients in prone/semi-prone position. Propofol based deep sedation has emerged as the method of choice however, the ability to predict possible complications is yet un-explored. AIMS: The present study aimed to evaluate known high risk-factors for general anesthesia (American Society of Anesthesiologists (ASA) status, body mass index (BMI), and Mallampati class) for their ability to affect outcomes in ERCP patients. STUDY DESIGN: Retrospective data of 653 patients who underwent ERCP during a period of 26 months at university hospital of Pennsylvania was reviewed. Patient-specific and procedure specific data was extracted. Desaturation was defined by fall of pulse oximeter saturation below 95% and its relation to patient specific high risk-factors was analyzed. RESULTS: Only 45 patients had transient de-saturation below 95% without any residual sequlae. No statistically significant relation between desaturation episodes and patients higher ASA status or BMI or modified Mallampati (MMP) class was found. Despite 60% patients being ASA III/IV none required emergency intubation or procedural interruption. Optimal oxygenation and airway patency was maintained with high degree of success using simple airway maneuvers or conduit devices (nasal/oral trumpet) with oxygen supplementation in all patients. CONCLUSIONS: Unlike general anesthesia, pre-operative patient ASA status, higher MMP or increasing BMI does not bear relation with likelihood of patients desaturating during ERCP. In presence of vigilant apnea monitoring and careful dose titration of maintenance anesthetics with airway conduits, general anesthesia, emergency intubations, and procedure interruptions can be avoided.

Anesthesia for ERCP: Impact of Anesthesiologist's Experience on Outcome and Cost.

The present study evaluates the effect of anesthesiologist's experience in providing deep sedation for endoscopic retrograde cholangiopancreatography (ERCP) on cost and safety. Methodology. Perioperative records of 1167 patients who underwent ERCP were divided on the basis of anesthesiologist assisting these procedures either on regular basis (Group R) or on ad hoc basis (Group N). Comparisons were made for anesthesia times, complication rates, and airway interventions. Results. Across all American Society of Anesthesiologists (ASA) Classes, regular anesthesiologists were more efficient (overall mean anesthesia time in Group R was 24.82 ± 12.96 versus 48.63 ± 21.53 minutes in Group N). Within Group R, anesthesia times across all ASA classes were comparable. In Group N, anesthesia times for higher ASA status patients were significantly longer (ASA IV, 64.62 ± 35.78 versus ASA I, 45.88 ± 11.19 minutes). Intubation rates (0.76% versus 12.8%) and median minimal oxygen saturation (100% versus 97.01%) were significantly higher in Group R. Had Group R anesthesiologists performed all procedures, the hospital could have saved US $ 758536 (based upon operating room time costs). Conclusion. Experience in providing deep sedation improved patient safety and decreased the operating room turnaround time, thereby lowering operating room costs associated with these procedures.