High intraabdominal pressure: effects on clinical parameters and lung pathology in baboons (Papio cynocephalus and Papio anubis)

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.

Partial amniotic carbon dioxide insufflation for fetal surgery

Partial amniotic carbon dioxide insufflation (PACI) involves insufflating the amniotic sac with carbon dioxide (CO₂ ) and, in some cases, draining some of the amniotic fluid. The creation of a gaseous intra-amniotic compartment improves visualization, even in the presence of limited bleeding, and creates the work space required for complex fetoscopic procedures. Clinically, PACI is mostly used to perform fetoscopic myelomeningocele (MMC) repair, enabling a minimally invasive alternative to open fetal surgery. However, evidence of the fetal safety of PACI is limited. Previous animal experiments in sheep demonstrate that PACI induces fetal hypercapnia and acidosis with largely unknown short and longer term implications. In this review, we examine the literature for the physiological effects of intrauterine insufflation pressure, duration, humidity, and the role of maternal hyperventilation on fetal physiology and well-being.

Variations of renal tissue oxygenation during abdominal compartment syndrome and sepsis

PURPOSE

This experimental study was designed to evaluate the renal tissue oxygenation under the coexistence of abdominal compartment syndrome and sepsis.

MATERIAL AND METHODS

Fourteen non-breed dogs were divided into two groups: the control group (8) and the study group (6). Sepsis was established with intravenous endotoxin infusion at 100μg/kg for over 30min. Insufflation of CO₂ in the peritoneal cavity was used for the increase in intra-abdominal pressure (IAP). A special catheter placed and fixed in the renal cortex at a depth of 3mm from the renal capsule was used for the measurement of renal tissue oxygenation.

RESULTS

Study parameters were recorded at the starting phase, at IAP of 15mmHg and 30mmHg and after decompression of the abdomen in the control group, and at the same intervals plus the induction of sepsis, prior to increasing abdominal pressure, in the study group. With the elevation of the IAP a reduction of renal tissue oxygenation presents itself, which is more pronounced in the presence of sepsis, especially for IAP over 15mmHg. Like other parameters, after abdominal decompression the renal tissue oxygenation returns to the initial levels, independently of sepsis.

CONCLUSIONS

The afferent arterioles vasoconstriction, which takes place during sepsis, and the intra-renal shunt, which occurs and leads to blood diversion to the medulla from the renal cortex due to the combination of intra-abdominal hypertension (IAH) and sepsis, seem to explain this finding.

Baboon model for the study of endometriosis

Endometriosis is a benign, estrogen-dependent disease and is now recognized as an enigmatic disease owing to its various clinical manifestations and locations. The lack of a reliable and specific method for the early detection of endometriosis often results in delayed diagnosis. So far, research has born inadequate findings regarding understanding the basic etiology or pathophysiology of endometriosis. Animal models that accurately represent the cellular and molecular changes associated with the initiation and progression of human endometriosis have significant potential to facilitate the development of better methods for the early detection and treatment of endometriosis. A number of animal model systems have been developed for the study of this disease. These models replicate many of the known salient features of human endometriosis. This review provides an insight into the use of the baboon model for studies focused on understanding human endometriosis.

Future directions in endometriosis research

Future research in endometriosis must focus on pathogenesis studies in the baboon model, the early interactions between endometrial and peritoneal cells in the pelvic cavity at the time of menstruation, and potential differences between eutopic endometrium and myometrium in women with and without endometriosis. More integration is needed between the areas of epidemiology and genetics. Pelvic inflammation in women with endometriosis could be the target for new diagnostic and therapeutic approaches. Important questions remain regarding the relationship between endometriosis and environmental factors. Systemic and extrapelvic manifestations of endometriosis must be analyzed carefully, and better tools are needed to measure quality of life in women with chronic pain caused by endometriosis. Most current evidence supports a causal relationship between endometriosis and subfertility, and the spontaneous progressive nature of endometriosis has been demonstrated in 30% to 60% of patients. Recurrence of endometriosis after classic medical and surgical therapy is a major and underestimated problem, especially in women with advanced disease. Integrated clinical and research teams are needed that combine expert medical, surgical, and holistic care with state-of-the-art research expertise in immunology, endocrinology, and genetics to discover new diagnostic methods and medical treatments for endometriosis.

A modified baboon model for endometriosis

Endometriosis is one of the most common causes of infertility and chronic pelvic pain and affects 1 in 10 women in the reproductive-age group. Although existence of this disease has been known for over 100 years, our current knowledge of its pathogenesis, the pathophysiology of related infertility, and its spontaneous evolution is limited. Several reasons contribute to our lack of knowledge, the most critical being the difficulty in carrying out objective long-term studies in women. Thus, we and others have developed the baboon as an appropriate nonhuman primate to study the etiology of this disease. We suggested that endometriosis develops in two distinct phases. Phase I is invasive and dependent on ovarian steroids. Phase II, which is the active phase of the disease, is characterized by endogenous estrogen biosynthesis. Following inoculation with menstrual endometrial tissues in two consecutive menstrual cycles, baboons develop lesions that are similar to those seen in humans. Laparoscopy at 1, 4, and 10 months revealed a preponderance of red raised nodules at the first month, while both red lesions and reddish-blue proliferative endometriotic lesions were evident at 4 and 10 months. The presence of glandular tissue and stromal fibroblasts in these lesions was confirmed by histology. Lesions obtained at 1 and 4 months expressed estrogen receptor beta (ERbeta), matrix metalloproteinase-7 (MMP-7), and vascular endothelial growth factor (VEGF) predominantly. However, aromatase expression was only readily evident at 10 months, although some lesions obtained at 4 months expressed low levels of aromatase. Therefore, our preliminary data suggest that endometriosis can be artificially induced in baboons, and the role of exogenous and endogenous estradiol in proliferation, angiogenesis, and immune modulations can now be evaluated in a potentially systemic manner.

Induced abdominal compartment syndrome increases intracranial pressure in neurotrauma patients: a prospective study

OBJECTIVE

To evaluate the effect of a stepwise increase in intra-abdominal pressure (IAP) on intracranial pressure (ICP) and to further define the pressure transmission characteristics of different body compartments.

DESIGN

A prospective, nonrandomized study.

SETTING

A multidisciplinary intensive care unit at a university medical center.

PATIENTS

Fifteen patients with moderate-to-severe head injury.

INTERVENTIONS

All patients were studied after the initial stabilization and resolution of intracranial hypertension. Measurements were carried out before and 20 mins after IAP was increased by positioning a soft, 15-L water bag on the patient's abdomen.

MEASUREMENTS AND MAIN RESULTS

Placing weights upon the abdomen generated a significant increase in IAP, which rose from 4.7 +/- 2.9 to 15.5 +/- 4.1 mm Hg (p <.001). The rise in IAP caused concomitant and rapid increases in central venous pressure (from 6.2 +/- 2.4 to 10.4 +/- 2.9 mm Hg; p <.001), internal jugular pressure (from 11.9 +/- 3.2 to 14.3 +/- 2.4 mm Hg; p <.001), and ICP (from 12.0 +/- 4.2 to 15.5 +/- 4.4 mm Hg; p <.001). Thoracic transmural pressure, calculated as the difference between central venous pressure and esophageal pressure, remained constant during the protocol. Respiratory system compliance decreased from 58.9 +/- 9.8 to 44.9 +/- 9.4 mL/cm H2O (p <.001) in all patients because of decreased chest wall compliance. The mean arterial pressure increased from 94 +/- 11 to 100 +/- 13 mm Hg (p <.01), which allowed the maintenance of a stable cerebral perfusion pressure (82.4 +/- 10.3 vs. 84.7 +/- 11.5 mm Hg; p = NS) despite the ICP increase.

CONCLUSIONS

Increased IAP causes a significant rise in ICP in head trauma patients. This effect seems to be the result of an increase in intrathoracic pressure, which causes a functional obstruction to cerebral venous outflow. Routine assessment of IAP may help clinicians to identify remediable causes of increased ICP. Caution should be used when applying laparoscopic techniques in neurotrauma patients.

Clinical relevance of the baboon as a model for the study of endometriosis

OBJECTIVE

To review the value of the baboon as a model for the study of endometriosis.

DATA IDENTIFICATION AND SELECTION

Studies performed at the Institute of Primate Research in Nairobi, Kenya (1990-1994), and published in peer-reviewed journals.

RESULT(S)

Spontaneous endometriosis was found in about 25% of the baboons, and its prevalence increased with the duration of captivity. The laparoscopic appearance, pelvic localization, and microscopic aspects of the disease were similar to endometriosis in women. Microscopic endometriosis in macroscopically normal peritoneum was rare. Sampson's hypothesis (i.e., retrograde menstruation causes endometriosis) was supported by the increased incidence of retrograde menstruation in baboons with spontaneous endometriosis, the observation that cervical occlusion could cause retrograde menstruation and endometriosis, and the finding that intrapelvic injection of menstrual endometrium caused experimental moderate to severe endometriosis similar to the spontaneous disease. During follow-up of more than 2 years, endometriosis in baboons appeared to be a progressive disease, with active remodeling between several types of lesions. Progression was stimulated by high-dose immunosuppression. Fertility was normal in baboons with minimal disease but was reduced in baboons with mild, moderate, or severe endometriosis, possibly related to an increased incidence and recurrence of the luteinized unruptured follicle syndrome.

CONCLUSION(S)

The baboon is a good model for the study of endometriosis.