Ideal versus corrected body weight for dosage of sugammadex in morbidly obese patients

Anaesthetists' drug dosing practices in class III obese surgical patients: A bi-national survey

Class III obese (body mass index ≥ 40 kg/m2) patients, now regularly encountered clinically, have increased perioperative risks, including potentially from suboptimal drug dosing. However, current dosing guidelines are based on low-level evidence and may not be widely accepted. This study aimed to investigate anaesthetists’ dosing practices for class III obese surgical patients, explore if they had experienced an increased incidence of adverse events potentially related to drug dosing with these patients and assess which resources they consulted for dosing advice in this population. An electronic survey was emailed to 1000 randomly selected members of the Australian and New Zealand College of Anaesthetists. Data were summarised and the Pearson’s χ2 test was used to compare respondents’ genders, geographic locations and seniority designations with the greater Australian and New Zealand College of Anaesthetists’ membership. There were 230 completed responses (response rate 23%). A large proportion (46%–76%) of respondents indicated they dose class III obese patients in keeping with current recommendations; however, substantial heterogeneity in dosing practices was found. Lean body weight was the most frequently used regimen for dosing propofol, non-depolarising muscle relaxants, sugammadex and opioids, whereas total body weight was most frequently used for suxamethonium. Nearly 70% of respondents reported using at least one resource to assist their dosing practices in obesity. Importantly, increased incidences of adverse events in class III obese patients related to drug dosing were commonly experienced by respondents. Until higher-level evidence is available for dosing class III obese patients, anaesthetists should consider current recommendations and exercise increased attention to dosing. Further clinician education may assist in optimising dosing in this patient group.

Sugammadex as a reversal agent for neuromuscular block: an evidence-based review

Sugammadex is the first clinical representative of a new class of drugs called selective relaxant binding agents. It has revolutionized the way anesthesiologists think about drug reversal. Sugammadex selectively binds rocuronium or vecuronium, thereby reversing their neuromuscular blocking action. Due to its 1:1 binding of rocuronium or vecuronium, it is able to reverse any depth of neuromuscular block. So far, it has been approved for use in adult patients and for pediatric patients over 2 years. Since its approval in Europe, Japan, and Australia, further insight on its use in special patient populations and specific diseases have become available. Due to its pharmacodynamic profile, sugammadex, in combination with rocuronium, may have the potential to displace succinylcholine as the "gold standard" muscle relaxant for rapid sequence induction. The use of rocuronium or vecuronium, with the potential of reverse of their action with sugammadex, seems to be safe in patients with impaired neuromuscular transmission, ie, neuromuscular diseases, including myasthenia gravis. Data from long-term use of sugammadex is not yet available. Evidence suggesting an economic advantage of using sugammadex and justifying its relatively high cost for an anesthesia-related drug, is missing.

Anesthetic Pharmacology and the Morbidly Obese Patient

Anesthesiologists are increasingly being faced with treating obese patients. Physiologic and anthropometric associated with obesity-most notably increases in cardiac output, changes in tissue perfusion and increases in total body weight (TBW), lean body weight (LBW), and fat mass affect the pharmacokinetics (PK) of anesthetic agents. In addition, redundancy of airway tissue, obstructive and central sleep apnea and CO2 retention affect the pharmacodynamics (PD) of anesthetics and narrow the therapeutic window of numerous anesthetic drugs. Safe and effective pharmacologic management of the obese patient requires a thorough understanding of how obesity affects the PK and PD of anesthetics.