Pneumoperitoneum during laparoscopic bariatric surgery induces carbon dioxide absorption and may lead to perioperative alterations in acid-base balance. Serum bicarbonate (HCO₃-) plays a central role in metabolic compensation; however, the clinical relevance of perioperative bicarbonate changes remains insufficiently defined.

This prospective observational study aims to evaluate the association between pneumoperitoneum duration and perioperative serum bicarbonate change (ΔHCO₃-), and to investigate whether ΔHCO₃- is associated with early discharge readiness at 48 hours (DR-48) following laparoscopic bariatric surgery. Patients undergoing laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass will be enrolled consecutively. No alteration of routine clinical care will occur.

Inclusion Criteria:

• Adults aged ≥18 years
• ASA physical status I-III
• Scheduled for elective laparoscopic bariatric surgery (laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass)
• Provided written informed consent

Exclusion Criteria:

• Age <18 years
• ASA physical status IV or higher
• Chronic obstructive pulmonary disease (COPD), asthma, or other severe chronic respiratory disease
• Known chronic metabolic acidosis or renal failure
• Major intraoperative complications (e.g., severe bleeding, conversion to open surgery)
• Postoperative reoperation, intensive care requirement, or complications preventing standard recovery evaluation

Adult patients undergoing elective laparoscopic bariatric surgery (laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass) at a single tertiary care center. Participants will be enrolled consecutively and followed prospectively to assess perioperative serum bicarbonate changes and early discharge readiness without altering routine clinical management.