Preoperative Toxicological Screening on Perioperative Anesthetic Management

The Middle East and North Africa (MENA) region has experienced a particularly rapid increase in obesity prevalence over recent decades, with some countries reporting rates exceeding 35% among adults. This trend is attributed to rapid urbanization, economic development, adoption of Western dietary patterns, and reduced physical activity. The high prevalence of obesity in the MENA region has created an urgent need for effective treatment strategies, including metabolic bariatric surgery (MBS).

MBS has established itself as the most effective long-term treatment for severe obesity, offering substantial and sustained weight loss along with resolution of obesity-related medical problems. The field has evolved significantly over the past decades, with procedures such as laparoscopic sleeve gastrectomy (LSG), Roux-en-Y gastric bypass (RYGB), and one-anastomosis gastric bypass (OAGB) becoming standard treatments for patients with severe obesity. These procedures not only achieve significant weight reduction but also provide remarkable improvements in type 2 diabetes, hypertension, dyslipidemia, and other obesity-related conditions.

The success of MBS depends on careful patient selection, thorough preoperative evaluation, and appropriate perioperative management. Substance use has become an important consideration among the factors influencing surgical outcomes. Substance use can affect wound healing and adherence to postoperative care protocols, potentially compromising surgical outcomes.

Managing anesthesia for obesity surgery in patients with substance abuse disorders presents a complex array of challenges. Obesity complicates airway management, alters pharmacokinetics and dynamics, demanding careful drug dosing and vigilant cardiopulmonary monitoring. Furthermore, chronic opioid users exhibit exaggerated pain, requiring dose modifications perioperatively but escalating risks of respiratory depression and postoperative hyperalgesia or withdrawal. Cocaine and amphetamine abuse increase the risks of arrhythmias, hypertension, myocardial ischemia, and unpredictable interactions with anesthetic agents. There is a necessity for multidisciplinary comprehensive perioperative optimization, including addiction consultation, careful substance withdrawal management, individualized anesthetic and surgical plans, multimodal analgesia, and extended postoperative monitoring for the possibility of respiratory complications and acute withdrawal symptoms.

A recent study by Chao et al. examined the association between toxicology positivity and outcomes in MBS patients in a retrospective review of 1,057 patients who underwent laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass. They found that 12.7% of patients had positive toxicology testing, with benzodiazepines (5.6%), opiates (3.5%), and cotinine (2.0%) being the most common substances detected. Their study did not find significant associations between toxicology positivity and preoperative length of time, 30-day complications, readmissions, or one-year weight loss.

In a cross-sectional study of elective surgery patients, Amin et al. found a strong positive correlation between toxicological screening drug detection and propofol induction dose, pain scores, and hospital stay. Similar findings were reported by Clavijo et al. in a prospective observational pilot study of patients undergoing spine surgery. They found inconsistencies between self-reporting and toxicological screening test results in 88% of patients, with significant correlations between polypharmacy and increased anesthesia requirements.

The MENA region provides unique challenges concerning substance use assessment owing to cultural, religious, and legal factors that may impact disclosure. Substance use is often stigmatized and criminalized in many MENA countries, potentially leading to underreporting during clinical evaluations. Epidemiological statistics show that drug usage patterns in the MENA region deviate from worldwide trends, with specific concerns about tramadol, cannabis, and prescription drugs. Tobacco usage remains prevalent throughout the area, with worries raised regarding the use of traditional medicines such as khat in certain regions. These drug use patterns have significant consequences for surgical patients because they may influence perioperative treatment, anesthetic requirements, and postoperative recovery. The stigmatization and underreporting of drug addiction in the MENA region highlights the importance of objective assessment methods, such as toxicological screening, to identify patients who may require modified perioperative management for patient safety and optimal care delivery.

The role of preoperative toxicological screening has been the subject of increasing research interest, particularly in procedures requiring careful perioperative management and in areas of uncertainty about patients' substance use disclosure. Despite the growing body of literature on this topic, there remains a gap in knowledge regarding the specific impact of preoperative substance use on outcomes following MBS, particularly in the MENA region, where substance use patterns and disclosure behaviors may differ from Western populations. This prospective observational study addressed this gap by evaluating the association between preoperative toxicological screening results and their impact on perioperative anesthetic management and short-term outcomes following MBS in Egypt.

Inclusion criteria

• adult patients (≥18 years) with obesity who were scheduled to undergo primary MBS, including laparoscopic sleeve gastrectomy (LSG), Roux-en-Y gastric bypass (RYGB), or one-anastomosis gastric bypass (OAGB)
• Patient selection followed the 2022 American Society for Metabolic and Bariatric Surgery (ASMBS) and International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) guidelines for MBS

Exclusion criteria

• previous bariatric or major abdominal surgery
• emergency procedures
• chronic pain syndromes
• severe psychiatric illness
• patient refusal that would impair informed consent or compliance with study protocols
• inability to complete follow-up assessments