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Vitish-Sharma, Parveen (2018) The effect of Trendelenburg positioning in laparoscopic colorectal surgery on intraocular pressure and cognitive function. PhD thesis, University of Nottingham.

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Abstract

Trendelenburg positioning is frequently used during laparoscopic surgery particularly when access to the pelvis is required. With improvements in laparoscopic skills, high risk patients and more complex procedures are now frequently being performed laparoscopically. (Improvement, 2016) The aim of this thesis is to investigate the effect of Trendelenburg positioning on intraocular pressure (IOP) and cognitive function.

Chapters 2 and 4 look at the effect of Trendelenburg positioning on IOP. Perioperative vision loss occurs rarely but it is a life changing complication. A rise in IOP is a recognised risk factor for POVL. The incidence of POVL following laparoscopic colorectal surgery has been quoted as 1.24 in 10,000 cases. (Pinkney et al., 2012) Chapter 2 is an observational study during which IOP was monitored during laparoscopic colorectal surgery. This was correlated with the degree of Trendelenburg tilt used during surgery. This study revealed an increase in IOP occurred which was dependent on the degree of Trendelenburg tilt as well as the time spent in this position (Pearson’s correlation coefficient was 0.78). Patients undergoing left-sided colonic resections had a mean maximum IOP rise of 15.2mmHg. Chapter 4 is a follow-on study which looked at acetazolamide as a method of reducing the IOP rise that occurred whilst in the Trendelenburg position. This was a randomised placebo controlled cross-over healthy volunteer study. After 4 hours of Trendelenburg, the mean IOP increase was 3.17mmHg in the placebo group compared to 0.02mmHg in the acetazolamide group (P<0.05). This suggests acetazolamide has a role in reducing the IOP rise that occurs from Trendelenburg positioning.

The second half of this thesis focuses on the effect of Trendelenburg positioning on cognitive function. Post-operative cognitive decline (POCD) is defined as cognitive impairment following surgical intervention. It is associated with increased hospital stay, longer return to work/normal functioning, and in patients with existing cognitive impairment a further decline can result in loss of ability to carry out activities of daily living. (Moller et al., 1998) Chapter 5 is an observational study that explores the incidence of short- or long-term POCD following laparoscopic colorectal surgery. Post-resectional surgery, 55.4% of patients had evidence of POCD on Day 1 and 31.6% at long-term follow-up. On Day 2, 11.6% had POCD following right-sided resection compared to 16.3% in the left-sided resection group. Chapter 6 and 7 look at the effect of Trendelenburg positioning on cognitive function in healthy volunteers.

Chapter 6 assessed changes in brain function using magnetoencephalography and n-back testing as well as looking at MRI structural changes after 2 hours in Trendelenburg position. Although the difference was not statistically significant, there was an increase in brain volume after 2 hours in Trendelenburg compared to pre-Trendelenburg MRI scan suggesting an element of cerebral oedema. Chapter 7 was a volunteer study designed to assess the effect of time spent in Trendelenburg position on cognitive function using cognitive tests (n back, stroop and lexical decision making tasks). This was carried out at regular intervals whilst in the Trendelenburg position and again once the volunteer was placed supine. After 3 hours in the Trendelenburg position, 40% had cognitive decline compared to 26.7% after 30 minutes.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Acheson, Austin Maxwell-Armstrong, Charles
Keywords:	Trendelenburg; POCD; POVL; IOP
Subjects:	W Medicine and related subjects (NLM Classification) > WI Digestive system
Faculties/Schools:	UK Campuses > Faculty of Medicine and Health Sciences > School of Medicine
Item ID:	48966
Depositing User:	Vitish-Sharma, Parveen
Date Deposited:	12 Jul 2018 04:40
Last Modified:	08 May 2020 09:00
URI:	https://eprints.nottingham.ac.uk/id/eprint/48966

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