Effects of Individualised High Positive End-Expiratory Pressure and Crystalloid Administration on Postoperative Pulmonary Function in Patients Undergoing Robotic-Assisted Radical Prostatectomy: A Prospective Randomised Single-Blinded Pilot Study

OBJECTIVES

Robotic-assisted laparoscopic prostatectomy (RALP) is typically conducted in steep Trendelenburg position (STP). The aim of the study was to evaluate whether crystalloid administration and individual management of positive end-expiratory pressure (PEEP) improve peri- and post-operative pulmonary function in patients undergoing RALP.

DESIGN

Prospective randomised single-centre single-blinded explorative study.

SETTING

Patients were either allocated to a standard PEEP (5 cmH₂O) group or an individualised high PEEP group. Furthermore, each group was divided into a liberal and a restrictive crystalloid group (8 vs. 4 mL/kg/h predicted body weight). Individualised PEEP levels were determined by means of preoperative recruitment manoeuvre and PEEP titration in STP.

PARTICIPANTS

Informed consent was obtained from 98 patients scheduled for elective RALP.

INTERVENTIONS

The following intraoperative parameters were analysed in each of the four study groups: ventilation setting (peak inspiratory pressure [PIP], plateau pressure, driving pressure [P_driv], lung compliance [LC] and mechanical power [MP]) and postoperative pulmonary function (bed-side spirometry). The spirometric parameters Tiffeneau index (FEV₁/FVC ratio) and mean forced expiratory flow (FEF_25-75) were measured pre- and post-operatively. Data are shown as mean ± standard deviation (SD), and groups were compared with ANOVA. A p-value of <0.05 was considered significant.

RESULTS

The two individualised high PEEP groups (mean PEEP 15.5 [±1.71 cmH₂O]) showed intraoperative significantly higher PIP, plateau pressure and MP levels but significantly decreased P_driv and increased LC. On the first and second postoperative day, patients with individualised high PEEP levels had a significantly higher mean Tiffeneau index and FEF_25-75. Perioperative oxygenation and ventilation and postoperative spirometric parameters were not influenced by restrictive or liberal crystalloid infusion in either of the two respective PEEP groups.

CONCLUSIONS

Individualised high PEEP levels (≥14 cmH₂O) during RALP improved intraoperative blood oxygenation and resulted in more lung-protective ventilation. Furthermore, postoperative pulmonary function was improved for up to 48 h after surgery in the sum of the two individualised high PEEP groups. Restrictive crystalloid infusion during RALP seemed to have no effect on peri- and post-operative oxygenation and pulmonary function.

The Impact of Steep Trendelenburg Position on Intraocular Pressure

Intraocular pressure occurring during the Trendelenburg position may be a risk for postoperative visual loss and other ocular complications. Intraocular pressure (IOP) higher than 21 mmHg poses a risk for ocular impairment causing several conditions such as glaucoma, detached retina, and postoperative vision loss. Many factors might play a role in IOP increase, like peak expiratory pressure (PIP), mean arterial blood pressure (MAP), end-tidal CO₂ (ETCO₂) and surgical duration and some others (anaesthetic and neuromuscular blockade depth) contribute by reducing IOP during procedures requiring both pneumoperitoneum and steep Trendelenburg position (25–45° head-down tilt). Despite transient visual field loss after surgery, no signs of ischemia or changes to the retinal nerve fibre layer (RNFL) have been shown after surgery. Over the years, several studies have been conducted to control and prevent IOPs intraoperative increase. Multiple strategies have been proposed by different authors over the years to reduce IOP during laparoscopic procedures, especially those involving steep Trendelenburg positions such as robot-assisted laparoscopic prostatectomy (RALP), and abdominal and pelvic procedures. These strategies included both positional and pharmacological strategies.

Quantitative rise in intraocular pressure in patients undergoing robotic surgery in steep Trendelenburg position: A prospective observational study

BACKGROUND AND AIMS

Raised intraocular pressure (IOP) is one of the known causes of anterior ischemic optic neuropathy. In the case of robotic urological-gynecological surgeries, patient is kept in steep Trendelenburg supine-lithotomy position. Aim of this study was to observe the quantitative rise in IOP in steep Trendelenburg position (>45°) in robotic-assisted prostatectomy and hysterectomy.

MATERIAL AND METHODS

After institutional ethical clearance and written informed consent, 100 patients undergoing robotic surgeries in steep Trendelenburg position were recruited for the study. IOP was measured at different time intervals in steep Trendelenburg position using Schiotz tonometer: Post intubation (T1), post pneumoperitoneum (T2), post steep Trendelenburg (T3), and rest readings were taken 30 min apart. T9 was taken 10 min after patient is made supine and parallel to the ground. Mean arterial pressure (MAP), positive inspiratory pressure (PIP), and end-tidal carbon dioxide (EtCO2) values were recorded at different time points. Descriptive analysis, linear regression analysis, and Freidman's nonparametric tests were used to analyze the results.

RESULTS

Ninety-five patients were included for statistical analysis as five patients were excluded due to intraoperative interventions leading to alteration of results. Mean IOP at T1 was 19.181/18.462 mmHg in L/R eye. A gradual rise in IOP was observed with every time point while patient was in steep Trendelenburg position which reverts back to near normal values once the patient is changed to normal position 21.419/20.671: Left/right eye in mm of Hg. Uni and multiple regression analysis showed insignificant P value, thus no correlation between MAP, PIP, and EtCO2 with IOP.

CONCLUSION

Steep Trendelenburg position for prolong duration leads to significant rise in intraocular pressure.

Ocular parameters before and after steep Trendelenburg positioning for robotic-assisted laparoscopic radical prostatectomy

Purpose

Intraocular pressure (IOP) increases in patients in a steep Trendelenburg position during robotic-assisted laparoscopic radical prostatectomy (RALP). We hypothesized that a steep Trendelenburg position during RALP, an unusual systemic condition involving a transiently increased IOP, may induce ocular pathology that can be detected by detailed evaluations long after the surgery. This study aims to explore ocular structural and functional parameters in patients before and in the long term after the surgery.

Patients and methods

A comparative observational study was performed. A total of 44 eyes of 22 male patients scheduled for RALP at Aichi Medical University from August 2012 to July 2013 were included. Clinical parameters before and after RALP were compared. Perioperative IOP was measured immediately post-induction of anesthesia in the flat supine position (T1), immediately post-steep Trendelenburg position (T2), and prior to returning to a flat supine position while in a steep Trendelenburg position (T3). The thicknesses of the peripapillary retinal nerve fiber layer, ganglion cell complex (GCC), and central fovea were measured with spectral domain optical coherence tomography. Humphrey perimetry was performed before and at 3 and 6 months after surgery.

Results

The average IOPs (mmHg) at each stage were T1=10.4, T2=21.7, and T3=29.6, and differed significantly. The mean visual acuity (logarithm of the minimal angle of resolution), IOP, mean deviation, and pattern standard deviation measured by the Humphrey field analyzer showed no statistically significant difference before and after surgery. The ganglion cell complex and retinal nerve fiber layer thicknesses measured at each location and the central fovea thicknesses measured before and after surgery did not differ significantly.

Conclusion

No significant disorders in ocular structural and functional parameters were found until long after RALP.

Changes in intraocular pressure and optic nerve sheath diameter in patients undergoing robotic-assisted laparoscopic prostatectomy in steep 45° Trendelenburg position

Background

To evaluate changes in intraocular pressure (IOP) and intracerebral pressure (ICP) reflected by the optic nerve sheath diameter (ONSD) in patients undergoing robotic-assisted laparoscopic prostatectomy (RALP) in permanent 45° steep Trendelenburg position (STP).

Methods

Fifty-one patients undergoing RALP under a standardised anaesthesia. IOP was perioperatively measured in awake patients (T0) and IOP and ONSD 20 min after induction of anaesthesia (T1), after insufflation of the abdomen in supine position (T2), after 30 min in STP (T3), when controlling Santorini’s plexus in STP (T4) and before awakening while supine (T5). We investigated the influence of respiratory and circulatory parameters as well as patient-specific and time-dependent factors on IOP and ONSD.

Results

Average IOP values (mmHg) were T0 = 19.9, T1 = 15.9, T2 = 20.1, T3 = 30.7, T4 = 33.9 and T5 = 21.8. IOP was 14.0 ± 7.47 mmHg (mean ± SD) higher at T4 than T0 (p = 0.013). Univariate mixed effects models showed peak inspiratory pressure (PIP) and mean arterial blood pressure (MAP) to be significant predictors for IOP increase. Mean ONSD values (mm) were T1 = 5.88, T2 = 6.08, T3 = 6.07, T4 = 6.04 and T5 = 5.96. The ONSD remained permanently >6.0 mm during RALP. Patients aged <63 years showed a 0.21 mm wider ONSD on average (p = 0.017) and greater variations in diameter than older patients.

Conclusions

The combination of STP and capnoperitoneum during RALP has a pronounced influence on IOP and, to a lesser degree, on ICP. IOP is directly correlated with increasing PIP and MAP. IOP doubled and the ONSD rose to values indicating increased intracranial pressure. Differences in the ONSD were age-related, showing higher output values as well as better autoregulation and compliance in STP for patients aged <63 years. Despite several ocular changes during RALP, visual function was not significantly impaired postoperatively.

Trial registration

Z-2014-0387-6. Registered 8 July 2014.