Sugammadex dosing in morbidly obese patients
Sugammadex dose calculated according to IBW is insufficient for reversing both deep and moderate blockades in a considerable number of morbidly obese patients. (Image source: Thinkstock)
Can sugammadex reliably reverse a rocuronium-induced neuromuscular blockade even in morbidly obese patients? If so, how should we calculate the optimal dose to arrive at a safe reversal in these patients who are at risk for postoperative upper airway collapse?
Drug dosing is generally based on the volume of distribution for the loading dose. Muscle relaxants are hydrophilic and their volume of distribution is minimally affected by obesity: their dosage is based on ideal body weight (IBW). In contrast, the loading dose of lipophilic anesthetics is based on total body weight (TBW). Read more…
Is a sevoflurane-based anesthetic safer than a propofol-based anesthetic for patients whose surgery is performed in BCP? (Image source: Thinkstock)
Shoulder surgery is commonly performed in the beach chair position (BCP) because it’s easier to perform it in that manner. In that position, though, patients may be prone to greater risk than if they were supine. Indeed, blood flow to the brain decreases when the head is higher than the heart since gravity affects blood flow. Jugular venous bulb oxygen saturation (SjvO2) and externally placed cerebral oxygen probes indirectly represent cerebral blood flow and cerebral oxygenation. Dr. Kyung Y. Yoo (Professor, Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Chonnam, Gwangju, South Korea) and colleagues, in their article titled “Cerebral Oxygen Saturation Measured by Near-infrared Spectroscopy and Jugular Venous Bulb Oxygen Saturation during Arthroscopic Shoulder Surgery in Beach Chair Position under Sevoflurane-Nitrous Oxide or Propofol-Remifentanil Anesthesia,” compared jugular venous bulb and regional cerebral tissue oxygen saturation in patients who received either sevoflurane or propofol for shoulder surgery in the beach chair position. Read more…
Organ failure rates increased as tidal volume increased. (Image source: Thinkstock)
Most would agree that for patients with acute lung injury, tidal volumes should be low since higher tidal volumes can lead to lung trauma. Ventilation with high tidal volumes has also been shown to be a risk for lung injury. Can tidal volume influence outcome for patients who undergo cardiac surgery? Such patients usually have normal lungs before surgery. Respiratory mechanics are probably little affected during the short period that cardiac surgery patients are ventilated, yet systemic inflammation may be secondary to cardiopulmonary bypass and multiple transfusions, and inappropriately high ventilation may make it worse. Low ventilation, however, may result in atelectasis. In the study “High Tidal Volumes in Mechanically Ventilated Patients Increase Organ Dysfunction after Cardiac Surgery,” Dr. Francois Lellouche (Adjunct Professor, Centre de Recherche de l’Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec) and colleagues hypothesized that higher tidal volumes, delivered after surgery, would increase organ failure. Read more…
What do residents do in their downtime?
Low Activity residents reported significantly more depression, anxiety and stress than Friend-Focused or Family-Focused residents. (Image source: Thinkstock)
Residents have free time? In the article “What Do Residents Do When Not Working or Sleeping? A Multispecialty Survey of 36 Residency Programs,” published in the April 2012 issue of Academic Medicine, Dr. DeWitt C. Baldwin (scholar-in-residence, Education Division, Accreditation Council for Graduate Medical Education, Chicago, Illinois) and coauthors report that depending on the specialty, residents now have about 40 to 50 hours a week that consists of time that is free from clinical duties or sleep. Although the ACGME instituted a strict 80-hour-per-week limit on duty hours in 2003 primarily in an effort to decrease resident fatigue and improve patient safety, the effect on house staff well-being and lifestyle has also been of interest. The authors of this study surveyed 759 first- and second-year residents in 36 residency programs in the US and asked them what they were doing with the available significantly increased nonsleep free time. Read more…
Members of the Currie lab (2010-2011); From left to right: Kevin Currie, Sarah McDavid, Lei Zhu, Rebecca Brindley and Mark Jewell.
The May issue of Anesthesiology includes a research paper from Kevin Currie’s lab in the Department of Anesthesiology, Vanderbilt University School of Medicine, titled “Gabapentin inhibits catecholamine release from adrenal chromaffin cells.” In this “visit to the lab,” we learn more about the research interests of the Currie lab and the approaches used in the current paper.
Research in the Currie lab focuses on regulation of voltage-gated calcium channels and calcium-dependent exocytosis, the fundamental cellular/molecular mechanism underlying synaptic transmission and neuroendocrine hormone release. Primarily we investigate adrenal chromaffin cells that release a complex cocktail of catecholamines and other neuroendocrine hormones to mediate diverse physiological effects, including the sympathoadrenal stress response. Chromaffin cells also provide a versatile model that enables detailed mechanistic insight into stimulus-secretion coupling. Our overall goal is to understand the regulation of calcium channels and transmitter release under physiological conditions, and identify potential therapeutic targets for treatment of nervous and endocrine system disorders in which these finely tuned processes are disrupted. Read more…
Emergence from AZD-3043-induced hypnosis was rapid.
Propanidid is a short-acting hypnotic because of its metabolically labile ester moiety. It was withdrawn from the market because it was formulated in Cremophor EL®, which caused histamine release and adverse hemodynamic changes. AZD-3043 is a chemical analog of propanidid that was designed to be a rapidly metabolized hypnotic, like propranidid, but is formulated in a lipid emulsion, like propofol. In “AZD-3043: A Novel, Metabolically Labile Sedative-Hypnotic Agent with Rapid and Predictable Emergence from Hypnosis,” published online first on 23 April 2012, Dr. Talmage D. Egan (Professor of Anesthesiology, Department of Anesthesiology, University of Utah School of Medicine, Salt Lake City, Utah) and colleagues characterized the pharmacokinetic and pharmacodynamic aspects of AZD-3043. Read more…
Emergence after propofol anesthesia was faster when methylphenidate was added. (Image source: Thinkstock)
In October 2011, based on a study published in Anesthesiology, Page2Anesthesiology described how methylphenidate, or Ritalin®, might decrease emergence time from isoflurane anesthesia. In the article “Active Emergence from Propofol General Anesthesia Is Induced by Methylphenidate,” that appeared in this month’s Anesthesiology, Dr. Ken Solt (Assistant Professor, Department of Anaesthesia, Harvard Medical School; Assistant Anesthetist, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital; and Research Affiliate, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology) and colleagues examine the relationship between methylphenidate and recovery after propofol anesthesia.
Rats received either a bolus dose or continuous infusion with propofol. Some rats had implanted extradural electrodes that were used for electroencephalogram (EEG) experiments. Rats received 8 mg/kg propofol intravenously as a bolus dose. For propofol infusion, the final target concentration of propofol was 0.5 µg/ml above the highest propofol dose where purposeful movements occurred.
Rats who received a propofol bolus took 735 s to emerge, i.e, to regain the righting reflex, vs. 448 s for the animals that received the propofol bolus and 5 mg/kg intravenous methylphenidate. During propofol infusion, after administration of methylphenidate, all rats promptly showed signs of reversal; within 4 min, they had restoration of righting reflex. Using EEG measurements and with higher doses of propofol, methylphenidate administration resulted in an EEG consistent with arousal, though righting reflex was not immediately restored.
As noted in the previous Page2Anesthesiology post, further study is needed in humans. Certainly, patients who take methylphenidate require higher doses of propofol. In the accompanying editorial, “From the Edge of Oblivion: The Dance between Intrinsic Neuronal Currents and Neuronal Connectivity,” Drs. Max Kelz and Jamie Sleigh note that this and other studies “give us some valuable insight into the delicate dance between general anesthetic drugs and the natural wake and sleep systems of the brain.”
Giving risperidone after cardiac surgery only to patients with evidence of delirium avoids using the drug on patients who do not need it: extra cost and possible side effects can be avoided. (Image source: Thinkstock)
Moving forward, it is quite likely that we will see more patients with postoperative delirium. This is because the population is aging, older patients undergo more surgery (particularly cardiac surgery) than their younger counterparts, and delirium is common after cardiac surgery. Last month, Page2Anesthesiology summarized a study that showed the relationship between obstructive sleep apnea and postoperative delirium in patients undergoing elective single knee replacement surgery. Risperidone is used to prevent and treat delirium in patients with schizophrenic disorders. In the study “Early Treatment with Risperidone for Subsyndromal Delirium after On-pump Cardiac Surgery in the Elderly: A Randomized Trial,” published in the May issue of Anesthesiology, Dr. Sameh M. Hakim (Associate Professor, Department of Anesthesiology, Faculty of Medicine, Ain Shams University, Cairo, Egypt) and colleagues studied the relationship between risperidone and postoperative delirium in patients ≥ 65 years after on-pump cardiac surgery. Read more…
Helicopter transportation, based on regression analysis, was associated with a greater change in odds of survival compared to ground transportation. (Image source: Thinkstock)
For me, at least, the hospital’s helicopter looks impressive. We’re able to view it from one of the hallways leading to the OR. Patients like looking at it as they are wheeled into the operating room. Though perhaps an additional benefit is that it feeds into the hospital’s marketing, an important reason the helicopter is there is to transport traumatically injured patients. Does this make a difference? Indeed, transport by helicopter is expensive and its availability is limited. Is ground transportation just as good? Read more…
The May 2012 issue of Anesthesiology has posted. As Editor-in-Chief for the Journal, I am pleased to discuss some of the issue’s highlights for Page2Anesthesiology:
Early Treatment with Risperidone for Subsyndromal Delirium after On-pump Cardiac Surgery in the Elderly: A Randomized Trial and Targeted Prophylaxis of Postoperative Delirium
Active Emergence from Propofol General Anesthesia Is Induced by Methylphenidate and From the Edge of Oblivion: The Dance between Intrinsic Neuronal Currents and Neuronal Connectivity
Objective Assessment of the Immediate Postoperative Analgesia Using Pupillary Reflex Measurement: A Prospective and Observational Study and Pupillometry to Guide Postoperative Analgesia
Optic Nerve Sheath Diameter Used as Ultrasonographic Assessment of the Incidence of Raised Intracranial Pressure in Preeclampsia: A Pilot Study and
Imaging Intracranial Pressure: An Introduction to Ultrasonography of the Optic Nerve Sheath
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