Circadian Timing of Spinal Anaesthesia Affects Analgesia and Inflammatory Response in Cesarean Delivery
Evangelia Nikouli *
Department of Anaesthesiology, General Hospital of Komotini, Thrace, Greece.
Nikoleta Koutlaki
Department of Obstetrics and Gynaecology, Faculty of Medicine, Democritus University of Thrace, Greece.
Kostas Anagnostopoulos
Laboratory of Biochemistry, Faculty of Medicine, Democritus University of Thrace, Greece.
Soultania Anna Toubalidou
Faculty of Social, Political and Economic Sciences-Democritus University of Trace, Komotini, Thrace, Greece.
Christina Tsigalou
Laboratory of Hygiene and Environmental Protection, Department of Medicine, Democritus University of Thrace, Greece.
Pelagia Chloropoulou
Department of Anesthesiology, Alexandroupolis University Hospital, Democritus University of Thrace, 68100 Alexandroupolis, Greece.
*Author to whom correspondence should be addressed.
Abstract
Background: The timing of anaesthesia administration may influence both drug efficacy and postoperative recovery, and understanding these temporal variations is essential for optimising anaesthetic management and patient outcomes. In particular, circadian physiology modulates cardiovascular stress responses, immune function, hormonal secretion, and the pharmacokinetics and pharmacodynamics of anaesthetic agents, as well as pain perception, making time of day a potentially important determinant of perioperative outcomes. However, evidence on circadian effects in neuraxial anaesthesia for cesarean delivery remains limited, particularly regarding inflammatory and stress markers, highlighting the need to determine whether anaesthesia administration time affects block characteristics, postoperative pain, and biomarkers such as CRP and cortisol.
Aim: To assess how spinal anaesthesia timing affects block duration, postoperative pain, and CRP and cortisol levels in cesarean deliveries.
Methods: Ninety women were divided into three groups based on spinal anaesthesia timing: Group A (08:00–16:00), Group B (16:00–00:00), and Group C (00:00–08:00). Standardised spinal anaesthesia was administered. Sensory/motor blockade and pain (NRS) were assessed every 10 minutes. Blood samples for CRP and cortisol were collected preoperatively and at 2, 4, 24, and 48 hours postoperatively.
Results: Group C showed shorter sensory and motor blockade than Groups A and B (p<0.05). Time to first analgesic request was longest in Group A, while Group C reported the highest pain scores (p<0.05). CRP levels were significantly higher in Group B vs. Group A at 24 and 48 hours, and vs. Group C at 48 hours (p<0.05). Group B demonstrated the steepest CRP velocity, indicating a more rapid physiological stress response. BMI differences may have influenced biomarker dynamics.
Conclusion: Cesarean sections performed under spinal anaesthesia during the early daytime were associated with prolonged sensory and motor block, lower postoperative pain scores, and a more favourable CRP profile compared with procedures later in the day. In contrast, late‑afternoon and nighttime anaesthesia were linked to shorter block duration, higher pain scores, and increased inflammatory responses, with the most pronounced CRP increase observed in the late‑afternoon group. Distinct BMI–CRP correlation patterns across time groups further indicated that both the timing of spinal anaesthesia and patient characteristics shape the perioperative inflammatory profile. These findings indicate that time of day is a clinically relevant, modifiable factor in neuraxial anaesthesia for cesarean delivery and suggest that scheduling spinal anaesthesia in earlier daytime windows may optimise block quality, postoperative analgesia, and inflammatory response.
Keywords: Circadian rhythms, spinal anaesthesia, local anaesthetics, surgical stress