Comparison of indirect and direct blood pressure measurements in baboons during ketamine anaesthesia

Use of Laryngeal Mask and Anesthetic Management in Hamadryas Baboons (Papio hamadryas) Undergoing Laparoscopic Salpingectomy-A Case Series

The study aims to describe the anesthetic and airway management of baboons (Papio hamadryas) undergoing laparoscopic salpingectomy with a laryngeal mask airway (LMA) device. Eleven baboons received tiletamine-zolazepam and medetomidine; anesthesia was induced with propofol. An LMA was positioned for oxygen and isoflurane administration in spontaneous respiration. Heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), end tidal carbon dioxide (EtCO₂), minute volume (MV), and peripheral hemoglobin oxygen saturation (SpO₂) were recorded before (PREPP) and immediately after abdomen insufflation (PP1), at 10 (PP2), 20 (PP3), and 30 (PP4) minutes during pneumoperitoneum, and after (POSTPP) pneumoperitoneum. The respiratory rate was significantly higher at all times compared to PREPP. The end tidal carbon dioxide concentration was significantly higher at PP2, PP3, PP4, and POSTPP, compared to the previous times. The higher values for RR and EtCO₂ were registered at PP4: 22.7 (95% CI 17.6-27.8) breaths/min and 57.9 (95% CI 51.9-63.8) mmHg, respectively. The minute volume was significantly higher at PP4 and POSTPP compared to the other times. The higher value for MV was registered at POSTPP (269.1 (95% CI 206.1-331.8) mL/kg/min). This protocol is suitable for baboons undergoing laparoscopic salpingectomy. The LMA was easy to insert and allowed for good ventilation, gas exchange, and delivery of the anesthetic in spontaneous breathing baboons.

Blood Pressure Reference Intervals for Ketamine-sedated Rhesus Macaques (Macaca mulatta)

Appropriate calculation and use of reference intervals have widespread clinical and research implications. Unfortunately, reference intervals for blood pressure in one of the most commonly used NHP species, rhesus macaques (Macaca mulatta), have never been calculated. Although anesthetic drugs and noninvasive methods of blood pressure measurement both have known effects on blood pressure values, their use provides the safest, fastest, and most widely used approach to clinical evaluation and blood pressure collection in this species. We analyzed noninvasive blood pressure measurements from 103 healthy, ketamine-sedated, adult (age, 8 to 16 y) rhesus macaques, representing both sexes, with various body condition scores by using 2 types of sphygmomanometers at 3 different anatomic locations. Reference intervals were calculated for each device, in each location, thus establishing normative data beneficial to clinical veterinarians assessing animal health and encouraging researchers to use noninvasive methods. Age, body condition score, sex, type of sphygmomanometer, and location of cuff placement were all found to influence blood pressure measurements significantly, providing important information necessary for the appropriate interpretation of noninvasive blood pressure values in rhesus macaques.

Increased salt sensitivity in offspring of pregnancies complicated by experimental preeclampsia

Preeclampsia is a hypertensive disorder of pregnancy known to increase the risk of cardiovascular disease in mothers and offspring. Offspring exposed to a suboptimal intrauterine environment may experience altered fetal programming and subsequent long-term cardiovascular changes. This study investigated changes in the vascular response in offspring from experimental preeclampsia (EPE) induced by uterine artery ligation, in the absence of fetal growth restriction, compared to normal baboon pregnancies (controls), following a high salt diet challenge. After 1 week of standard diet (containing <1% salt), animals were fed a high salt diet (6%) for 2 weeks. Systolic and diastolic blood pressure (SBP, DBP), aldosterone, renin and creatinine clearance were evaluated in EPE (n = 6, 50% male) and control (n = 6, 50% male) offspring. A repeated measures analysis was performed, and P < 0.05 was considered significant. At baseline, there were no differences between the groups in any parameter (EPE, mean age and weight 3.2 ± 1.2 years, 6.8 ± 1.0 kg, respectively; Control, 2.9 ± 0.8 years, 7.1 ± 1.5 kg). After salt loading the EPE group had significantly higher SBP (92 ± 5 mm Hg) compared to the control group (83 ± 4 mm Hg, P = 0.03). Aldosterone concentration was higher in the EPE group despite the same salt excretion and no difference in renal function. Salt sensitivity may differ in offspring from hypertensive pregnancies due to fetal programming. This could have long-term consequences for cardiovascular health of EPE offspring and further research is required to determine the exact pathological mechanisms.

Diet-induced early-stage atherosclerosis in baboons: Lipoproteins, atherogenesis, and arterial compliance

BACKGROUND

The purpose of this study was to determine whether dietary manipulation can reliably induce early-stage atherosclerosis and clinically relevant changes in vascular function in an established, well-characterized non-human primate model.

METHODS

We fed 112 baboons a high-cholesterol, high-fat challenge diet for two years. We assayed circulating biomarkers of cardiovascular disease (CVD) risk, at 0, 7, and 104 weeks into the challenge; assessed arterial compliance noninvasively at 104 weeks; and measured atherosclerotic lesions in three major arteries at necropsy.

RESULTS

We observed evidence of atherosclerosis in all but one baboon fed the two-year challenge diet. CVD risk biomarkers, the prevalence, size, and complexity of arterial lesions, plus consequent arterial stiffness, were increased in comparison with dietary control animals.

CONCLUSIONS

Feeding baboons a high-cholesterol, high-fat diet for two years reliably induces atherosclerosis, with risk factor profiles, arterial lesions, and changes in vascular function also seen in humans.

A Cross-Sectional Study of Ageing and Cardiovascular Function over the Baboon Lifespan

Background

Ageing is associated with changes at the molecular and cellular level that can alter cardiovascular function and ultimately lead to disease. The baboon is an ideal model for studying ageing due to the similarities in genetic, anatomical, physiological and biochemical characteristics with humans. The aim of this cross-sectional study was to investigate the changes in cardiovascular profile of baboons over the course of their lifespan.

Methods

Data were collected from 109 healthy baboons (Papio hamadryas) at the Australian National Baboon Colony. A linear regression model, adjusting for sex, was used to analyse the association between age and markers of ageing with P < 0.01 considered significant.

Results

Male (n = 49, 1.5–28.5 years) and female (n = 60, 1.8–24.6 years) baboons were included in the study. Age was significantly correlated with systolic (R² = 0.23, P < 0.001) and diastolic blood pressure (R² = 0.44, P < 0.001), with blood pressure increasing with age. Age was also highly correlated with core augmentation index (R² = 0.17, P < 0.001) and core pulse pressure (R² = 0.30, P < 0.001). Creatinine and urea were significantly higher in older animals compared to young animals (P < 0.001 for both). Older animals (>12 years) had significantly shorter telomeres when compared to younger (<3 years) baboons (P = 0.001).

Conclusion

This study is the first to demonstrate that cardiovascular function alters with age in the baboon. This research identifies similarities within cardiovascular parameters between humans and baboon even though the length of life differs between the two species.

Comparison of the effects of ketamine and fentanyl-midazolam-medetomidine for sedation of rhesus macaques (Macaca mulatta)

Background

This study assessed the effects of sedation using a combination of fentanyl, midazolam and medetomidine in comparison to ketamine. Rhesus Macaques (Macaca mulatta), (n = 16, 5 males and 3 females randomly allocated to each treatment group) received either ketamine (KET) (10 mg.kg⁻¹) or fentanyl-midazolam-medetomidine (FMM) (10 μg/kg⁻¹; 0.5 mg.kg⁻¹; 20 μg.kg⁻¹) both IM. Oxygen (100 %) was provided by mask and heart rate, blood pressure, respiratory rate, EtCO₂ and depth of sedation were assessed every 5 min for 20 min. After the last time point, FMM monkeys were reversed with atipamezole-naloxone (0.2 mg.kg⁻¹; 10 μg.kg⁻¹). Recovery was scored using clinical scoring scheme. Differences in physiological parameters and quality of sedation were compared using Area Under the Curve (AUC) method and either Mann-Witney or t-student tests.

Results

Heart rate (beats/min) (Ket = 119 ± 18; FMM = 89 ± 17; p = 0.0066), systolic blood pressure (mmHg) (Ket = 109 ± 10; FMM = 97 ± 10; p = 0.0313), and respiratory rate (breaths/min) (Ket = 39 ± 9; FMM = 29 ± 10; p = 0.0416) were significantly lower in the FMM group. End-tidal CO₂ (mmHg) did not differ between the groups (KET = 33 ± 8; FMM = 42 ± 11; p = 0.0462)_. Although some depression of physiological parameters was seen with FMM, the variables all remained within the normal ranges in both groups. Onset of a sufficient degree of sedation for safe handling was more rapid with ketamine (KET = 2.9 ± 1.4 min; FMM = 7.9 ± 1.2 min; p = 0.0009), but FMM recovery was faster (KET = 21.4 ± 13.4 min; FMM = 9.1 ± 3.6 min; p = 0.0379) and of better quality (KET = 1.3 ± 0.9; FMM = 7.4 ± 1.9; p = 0.0009) most probably because of the effectiveness of the reversal agents used.

Conclusion

FMM provides an easily reversible immobilization with a rapid and good recovery quality and may prove a useful alternative to ketamine.