Effects of Crystalloid versus Colloid and the α-2 Agonist Brimonidine versus Placebo on Intraocular Pressure during Prone Spine Surgery: A Factorial Randomized Trial

• Published in: Anesthesiology (Philadelphia) 2012-04, Vol.116 (4), p.807-815
• Main Authors: FARAG, Ehab, SESSLER, Daniel I, KOVACI, Bledar, LU WANG, MASCHA, Edward J, BELL, Gordon, KALFAS, Lain, ROCKWOOD, Edward, KURZ, Andrea
• Format: Article
• Language: English
• Subjects: Adrenergic alpha-2 Receptor Agonists - administration & dosage; Adrenergic alpha-2 Receptor Agonists - chemistry; Adult; Aged; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Brimonidine Tartrate; Chemistry, Pharmaceutical; Colloids - administration & dosage; Colloids - chemistry; Female; Humans; Intraocular Pressure - drug effects; Intraocular Pressure - physiology; Intraoperative Care - methods; Isotonic Solutions - administration & dosage; Isotonic Solutions - chemistry; Male; Medical sciences; Middle Aged; Prone Position - physiology; Quinoxalines - administration & dosage; Quinoxalines - chemistry; Spinal Cord Diseases - drug therapy; Spinal Cord Diseases - surgery; Treatment Outcome
• ISSN: 0003-3022; 1528-1175
• DOI: 10.1097/ALN.0b013e3182475c10

Volume replacement with colloid solution and topical α-2 agonists may each moderate the progressive increase in intraocular pressure (IOP) during prone surgery. The authors tested the hypotheses that during prolonged prone surgery, IOP increases less with goal-directed intravenous administration of 5% albumin than with goal-directed administration of lactated Ringer's solution, and with topical α-2 agonist brimonidine than with placebo eye drops. Patients having complex prone spine surgery were factorially randomized to albumin and topical placebo (n = 15); albumin and topical brimonidine (n = 16); lactated Ringer's solution and topical placebo (n = 13); and lactated Ringer's solution and topical brimonidine (n = 16). IOP was measured with a pneumotonometer. The primary outcome was time-weighted average intraoperative IOP. Prone positioning increased IOP a mean ± SD of 12 ± 6 mmHg. IOP increased to 38 ± 10 mmHg at the end of anesthesia (approximately 5.5 h). Time- weighted average intraoperative IOP in the brimonidine group was 4 (95% CI: 1, 8) mmHg lower than in the placebo group (P = 0.023), but no different in the crystalloid and albumin groups (mean difference (95% CI) of -2 (-5, 2) mmHg (P = 0.34). There was no interaction between the two randomized factors. Brimonidine slightly reduced the primary outcome of intraoperative time-weighted average IOP, whereas there was no significant difference between goal-directed albumin or crystalloid administration. Brimonidine thus helps reduce IOP during spine surgery, but maintaining adequate blood pressure might play a more important role.