A Pilot Crossover Study in Healthy Volunteers to Assess the Effect of Acetazolamide on Intraocular Pressure After Being in the Trendelenburg Position.
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 9
- 主要终点
- Comparison of IOP pressure during Trendelenburg position after placebo and acetazolamide at each given time point outlined in methods.
研究概览
简要总结
Perioperative vision loss following laparoscopic colorectal surgery is rare but has been reported. Studies show Trendelenburg positioning during surgery can produce a significant rise in the IOP, and this rise is thought to be a possible factor. Acetazolamide decreases IOP by reducing the formation of aqueous humour.
Aims:
To investigate if acetazolamide reduces the IOP rise resulting from Trendelenburg positioning.
Methods:
A randomised cross-over blinded pilot study. Nine healthy volunteers were randomised to start with the placebo or Acetazolamide with a 5 days' washout period. Baseline IOP was measured on both days. After 1.5 hours of taking the medication, volunteers lay head-down at 17 degrees' for 4 hours and IOP measurements repeated. This reading was subtracted from the baseline to give a 'change in IOP'.
详细描述
Background:
Laparoscopic (keyhole) bowel surgery often requires positioning patients on the operating table in very steeply angled positions for up to four or more hours. There have been case reports of patients suffering cognitive impairment after surgery with long periods of Trendelenburg (person is lying flat at an incline where their head lies lower than their feet) positioning.
Evidence from other fields of surgery suggests that "head-down" positions can produce a significant rise in the intraocular pressure. Transient vision problems and loss of sight has been reported following surgery is rare instances, including one case after laparoscopic colorectal resection. The cause of this is not fully understood, but rises in intraocular pressure (IOP) has been suggested as a possible factor. This may be particularly relevant in patients who have pre-existing high baseline IOP as a result of glaucoma. Studies looking at the effect of Trendelenburg positioning have shown that there is an increase in IOP. This study is to assess the effect of acetazolamide on the IOP rise after being placed in the Trendelenburg position. Acetazolamide is a carbonic anhydrase inhibitor which is used to treat glaucoma. The drug works by decreasing aqueous humour formation. It can be given as eye drops (but the absorption of this is variable and therefore so is the effect), orally and intravenously. The oral dose can be given as a one off dose or a divided dose. Maximum onset of IOP reduction occurs 2 to 5 hours after taking an oral dose and duration is 6-8 hours.
Aims:
This study aims to investigate the effect of acetazolamide on the IOP rise whilst in the Trendelenburg position.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Prevention
- 盲法
- Triple (Participant, Investigator, Outcomes Assessor)
盲法说明
Placebo and Acetazolamide tablets were placed into capsules that were the same by the Pharmacy department. A separate investigator generated a randomisation list for 11 volunteers to decide if a placebo or acetazolamide will be taken on Day 1. They then created envelopes with the corresponding medication in Day 1 and the other in Day 2 and these were marked as Volunteer 1, 2, 3 etc. The randomisation list was sealed and kept with each investigator so they could be accessed if required due to any adverse events.
The volunteers will be recruited and both the investigators and the volunteers were blinded to what was received on each study day.
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Healthy volunteers aged 18 and over
排除标准
- •Pregnancy
- •Breast Feeding
- •Hepatic impairment
- •Patients with pre-existing conditions affecting IOP regulation eg Glaucoma, previous eye surgery
- •Regular medication affecting IOP
- •Under the age of 18
- •Refusal to give written informed consent
研究组 & 干预措施
Placebo and Trendelenburg Position
Volunteers received placebo medication and placed in Trendelenburg.
IOP will be measured. Participants will then be administered with a placebo and after 2.5 hours will be placed in 17 degrees head-down position for a minimum of 1 hour and maximum 4 hours. Repeat IOP measure will be taken whilst still in the Trendelenburg position after 5 mins and then every 30 minutes.
干预措施: Placebo (Drug)
Placebo and Trendelenburg Position
Volunteers received placebo medication and placed in Trendelenburg.
IOP will be measured. Participants will then be administered with a placebo and after 2.5 hours will be placed in 17 degrees head-down position for a minimum of 1 hour and maximum 4 hours. Repeat IOP measure will be taken whilst still in the Trendelenburg position after 5 mins and then every 30 minutes.
干预措施: Trendelenburg Position (Other)
Acetazolamide and Trendelenburg Position
Volunteer given acetazolomide and placed in Trendelenburg position and IOP measured.
IOP will be measured. Participants will then be administered with acetazolamide and after 2.5 hours placed in 17 degrees head-down position for a minimum of 1 hour and maximum 4 hours. Repeat IOP measure will be taken whilst still in the Trendelenburg position after 5 mins and then every 30 minutes.
干预措施: Acetazolamide (Drug)
Acetazolamide and Trendelenburg Position
Volunteer given acetazolomide and placed in Trendelenburg position and IOP measured.
IOP will be measured. Participants will then be administered with acetazolamide and after 2.5 hours placed in 17 degrees head-down position for a minimum of 1 hour and maximum 4 hours. Repeat IOP measure will be taken whilst still in the Trendelenburg position after 5 mins and then every 30 minutes.
干预措施: Trendelenburg Position (Other)
结局指标
主要结局
Comparison of IOP pressure during Trendelenburg position after placebo and acetazolamide at each given time point outlined in methods.
时间窗: 6 days. 2 Days involved in study (6 hours each) and a minimum of 5 days between study days to allow 'wash-out period' of drug.
IOP measurements will be taken at each described time point on both study days and the difference in IOP measurement after acetazolamide will be compared to those after placebo.
次要结局
未报告次要终点