Effects of propofol on intraocular pressure in premedicated and nonpremedicated dogs with and without glaucoma

Effects of propofol alone or in combination with ketamine on intraocular pressure in unpremedicated dogs

OBJECTIVE

To determine the effects of propofol (P) alone and in combination with ketamine (KP) at ratios of 1:1, 1:2, and 1:3 on intraocular pressure (IOP) in unpremedicated dogs.

ANIMALS STUDIED

A total of 28 cross-bred healthy dogs.

PROCEDURES

Dogs were randomly assigned to one of four groups (n = 7 per group) to receive intravenous P or KP at 1:1, 1:2, and 1:3 ratios, respectively. The infusion was administered at 0.6 mg/kg/min for 60 min. IOP, cardiorespiratory variables, rectal temperature (RT), and pedal reflex were recorded every 5 min for 60 min, starting from baseline (BL).

RESULTS

There was a statistically significant increase in IOP in all groups: P (p = .011), KP 1:1 (p = .003), KP 1:2 (p = .023), and KP 1:3 (p = .008). The IOP increase was less pronounced in the KP 1:2 group and was only significant (p = .023) at T45 compared with BL. A significant correlation was observed between IOP and SpO2 in P (r = -.215, p = .02), KP 1:2 (r = -.579, p < .01), and KP 1:3 (r = -.402, p < .01) groups. IOP significantly increased due to decreased SpO2 below 86.5% (p < .05).

CONCLUSIONS

Propofol alone and in combination with ketamine may increase preexisting IOP in unpremedicated dogs. SpO2 levels below 86.5% may trigger an increase in IOP. Administering KP in a 1:2 ratio at an infusion rate of 0.6 mg/kg/min does not significantly alter IOP for under 45 min in unpremedicated dogs with sufficient oxygenation.

Influence of ketamine, propofol or isoflurane on intraocular pressure, heart rate and blood pressure in healthy dogs premedicated with medetomidine and midazolam

BACKGROUND

According to the findings of several studies, sedatives and anaesthetics have different effects on the functioning of the cardiovascular system and intraocular pressure (IOP). For accurate diagnosis, treatment and surgery with minimal complications, it is necessary to be aware of the effects of sedatives and anaesthetics on the cardiovascular system and IOP.

OBJECTIVES

The aim of this study was to evaluate the effects of sedatives (medetomidine and midazolam) and anaesthetics (ketamine, propofol and isoflurane) on IOP, heart rate (HR) and blood pressure in dogs.

METHODS

In this study, 10 dogs participated in three treatments using a randomised cross-over design, with a 1-week washout period between each treatment. Dogs in all treatments were premedicated with medetomidine and midazolam. Anaesthesia was induced using ketamine, propofol, or isoflurane and maintained for 60 min with the appropriate doses of each drug. The cardiovascular variables (heart rate, and systolic, diastolic and mean arterial pressures) and IOP were measured at different timepoints: before premedication (baseline values, T-Bas), 15 min after medetomidine administration (T-Med), 20 min after midazolam administration (T-Mid) and at 15 (T-15), 30 (T-30), 45 (T-45) and 60 (T-60) min after anaesthesia induction.

RESULTS

Medetomidine significantly reduced the IOP and HR and did not significantly change the mean arterial pressure (MAP). Midazolam significantly reduced the IOP while did not significantly change the HR and MAP. Ketamine and isoflurane significantly increased the IOP and HR while did not significantly change the MAP. Propofol significantly increased the HR, but did not cause significant changes in IOP and MAP.

CONCLUSIONS

Considering that anaesthetics are typically administered in conjunction with pre-anaesthetic drugs, the increases in IOP induced by ketamine and isoflurane are not important, as the IOP did not exceed the baseline values. However, further studies are required to investigate these effects in patients with elevated IOP.

Effects of tiletamine-zolazepam vs. propofol on peri-induction intraocular pressure in dogs: A randomized, masked crossover study

Introduction

Anesthesia induction agents have the potential to cause severe ocular side effects, resulting in lasting damage to the eye.

Objectives

The purpose of this study is to determine the effects of tiletamine-zolazepam on IOP compared to propofol when they are used as an induction agent in normal healthy dogs.

Methods

Twenty healthy adult client owned dogs weighing 22.2 ± 7.6 kg were selected for the study. In a randomized order, all dogs received tiletamine-zolazepam 5 mg/kg IV or propofol 8 mg/kg IV titrated to effect without premedication. Washout between each treatment was at least seven days. IOP measurements were obtained at four time points: baseline, post-induction, post-intubation, and after recovery using applanation tonometry. No additional procedures were performed. After normality of the data was determined, a linear mixed model was built with time, eye, treatment and all interactions of those variables as fixed effects and subject as a random effect.

Results

There was no significant difference for age, body weight, drug dose, baseline IOP, and recovery IOP between treatments. Average IOP measurements remained within the normal range of 15-25 mmHg at these time points. However, IOP was significantly less elevated by the tiletamine-zolazepam treatment vs. propofol at the post-induction (mean difference: -4.7 ± 4.6 [95%CI -6.8 to -2.5]) and the post-intubation (mean difference: -4.4 ± 4.6 [95%CI -6.5 to -2.2]) time points.

Clinical significance

Dogs receiving tiletamine-zolazepam for anesthetic induction had a significantly less elevated IOP at induction and intubation compared to dogs receiving propofol.

Intraocular pressure and cardiovascular effects of dexmedetomidine premedication and tiletamine-zolazepam for anesthetic induction in dogs

Background and Aim

The effect of anesthetic drugs on intraocular pressure (IOP) is an important concern in ophthalmic surgery. The impact of dexmedetomidine (DEX) combined with tiletamine-zolazepam on IOP is scarcely studied. This study aimed to evaluate IOP and cardiovascular effects in dogs after premedication with 5 μg/kg (DEX5) or 10 μg/kg (DEX10) of intramuscular DEX followed by intravenous tiletamine-zolazepam administration for induction of anesthesia in healthy dogs.

Materials and Methods

Eighteen dogs, American Society of Anesthesiologists I or II, without ocular abnormality were investigated. All dogs were randomly divided into the DEX5 (n = 9) and DEX10 groups (n = 9). The IOP, heart rate (HR), systolic blood pressure (SBP), oxygen saturation, and sedation scale were measured before premedication (baseline), after premedication at 5, 10, 15, and 20 min, after tiletamine-zolazepam administration, after endotracheal intubation, and post-operative.

Results

There were no significant differences between the groups at any time point. The DEX5 and DEX10 groups had significantly decreased HR values at 10 min compared with baseline. The IOP at 20 min was significantly lower compared to the baseline in the DEX10 group. Moreover, the DEX10 group showed increased IOP, HR, SBP, and sedation scale values after induction and intubation compared with 20 min, but these values did not differ significantly from baseline. All parameters of both groups did not change significantly between post-operative and baseline.

Conclusion

Intramuscular DEX (10 μg/kg) is an appropriate premedication in ophthalmic examination or surgical procedures. Moreover, it could be combined with tiletamine-zolazepam for generalized anesthesia in dogs with an ophthalmic problem, as it had no clinically significant effects on IOP or cardiovascular values.

Morphometrical analysis of the canine choroid in relation to age and sex using spectral domain optical coherence tomography

This study determined the choroidal thickness of senior (SN, n = 24) and middle-aged (MA, n = 17) healthy, mixed-breed mesocephalic dogs, both males (M) and females (F), using spectral domain optical coherence tomography (SD-OCT). The dogs were divided into two groups for examination: MA dogs (4-7 years old; 6 M, 11 F) and SN dogs (8-13 years old; 12 M, 12 F). Choroidal thickness of the dogs was investigated using SD-OCT radial and linear scans. The software of the device allowed determination of the exact measurement location on the choroid. Measurements of the choroid were taken manually using the SD-OCT calliper function at distances of 5,000-6,000 μm (dorsal and ventral) and 4,000-7,000 μm (nasal and temporal) from the optic disc. Mean (µm ± SD) (MA, SN) dorsal (188 ± 28, 184 ± 33), ventral (116 ± 23, 111 ± 16), temporal (152 ± 31, 151 ± 26), and nasal (135 ± 27, 132 ± 18) choroidal thicknesses demonstrated significant differences (P < 0.02-0.001) between all areas within each group. The choroid was thickest in the dorsal region and thinnest in the ventral region. There were no significant differences based on age. Mean (µm ± SD) (M, F) dorsal (181 ± 32, 190 ± 30), ventral (117 ± 16, 11 ± 21), temporal (150 ± 26, 153 ± 30), and nasal (128 ± 20, 138 ± 23) choroidal thicknesses demonstrated significant differences (P < 0.05) between dorsal and nasal regions. The choroidal thickness in dogs depends on the area assessed independently of their age and sex.

Intraocular pressure and pupil diameter in healthy cats anesthetized with isoflurane and pre-medicated with isolated acepromazine or in combination with tramadol

ABSTRACT The objective of this study was to determine changes on intraocular pressure (IOP) and pupil diameter (PD) in healthy cats anesthetized with isoflurane, and premedicated with acepromazine alone or in combination with tramadol. Thirty cats were allocated in two groups (n=15/each) and were treated with acepromazine (AG) or acepromazine/tramadol (ATG). PD and IOP were assessed before and following 30 (PM1), and 40 minutes (PM2) of treatments. Anesthesia was induced with propofol, and IOP and DP were recorded (A10) at 10 minute intervals until the end of anesthesia (A40). IOP decreased in AG and ATG, when comparing baseline with PM1. IOP decreased only in AG, in comparisons between baseline and PM2. During anesthesia, IOP did not change within and between groups. Comparisons between baseline with those recorded at PM1 and 2 showed that PD increased in the ATG. During anesthesia, PD decreased significantly in AG and ATG. Both protocols maintained the IOP within the reference range to perform corneal or intraocular surgery in healthy cats but did not sustain pre-anesthetic pupil dilation observed in ATG.

A systematic review of the effects of injectable sedative and anesthetic drugs and inhalant anesthetics on intraocular pressure in the dog

OBJECTIVE

The purpose of this systematic review was to summarize the results of studies that have determined the effect of injectable and inhalant drugs used in anesthesia on intraocular pressure (IOP) in dogs.

DATABASES USED

A comprehensive search of research literature was performed without language restriction. The search utilized the PubMed, CAB Abstracts and the University of Georgia's Galileo electronic databases using a combination of free text terms 'Ophthalmology', 'Intraocular Pressure', 'Anesthetic', 'Anesthesia', 'Canine' or 'Dog'. The time frame searched was from 1970 to October 2018. Any published research paper that dealt with sedatives or anesthetics administered systemically and the canine eye was evaluated.

CONCLUSIONS

The effects of many anesthetic drugs in dogs with ocular pathology are largely unknown. Many anesthetic drugs do not induce clinically relevant changes in IOP in dogs with normal eyes, although some studies demonstrated results with statistically significant changes. The dose, route of administration, experimental conditions, drug combinations, timing of measurements, measurement technology and setting or individual animal characteristics may all produce some heterogeneity in results from multiple studies.

Treatment of canine postoperative ocular hypertension with combined latanoprost 0.005% and atropine 1% ophthalmic solutions

OBJECTIVE

To compare the effects of topical 0.005% latanoprost (L) vs combined 0.005% latanoprost and 1% atropine (LA) on control of postoperative ocular hypertension (POH), development of posterior synechiae formation, pupil size, and blindness after phacoemulsification surgery in dogs.

ANIMAL STUDIED

Dogs with postoperative ocular hypertension were included in the study: L-group, latanoprost (eight dogs, 14 eyes) and LA-group, latanoprost and atropine (nine dogs, 15 eyes).

PROCEDURES

Complete ophthalmic examinations including tonometry were performed at 1, 7, and 21 days following phacoemulsification.

RESULTS

No significant differences were found between the measured intraocular pressure (IOP) at days 1 and 7 postphacoemulsification surgery in the L-group and the LA-group (P = 0.26 [14.12 ± 1.76 mmHg vs 16.96 ± 1.68 mmHg] and P = 0.71 [15.45 ± 1.43 mmHg vs 16.20 ± 1.36 mmHg], respectively). No significant differences were found between pupil sizes at day 7 for the two groups (P = 0.25 [13.83% vs 24.77%]). No significant differences were found between odds of posterior synechiae formation at day 21 (P = 0.92) with a probability ± SE for L-group vs LA-group at 0.27 ± 0.14 vs 0.25 ± 0.13. No significant differences were found in odds of postoperative blindness between groups (P = 0.58) with a probability ± SE of 0.21 ± 0.11 vs 0.13 ± 0.09, respectively for L and LA.

CONCLUSIONS

Combined topical latanoprost and atropine in dogs maintains normal postoperative IOPs but does not seem to cause increased mydriasis compared to latanoprost alone.