Right on track? Performance of satellite telemetry in terrestrial wildlife research.

Satellite telemetry is an increasingly utilized technology in wildlife research, and current devices can track individual animal movements at unprecedented spatial and temporal resolutions. However, as we enter the golden age of satellite telemetry, we need an in-depth understanding of the main technological, species-specific and environmental factors that determine the success and failure of satellite tracking devices across species and habitats. Here, we assess the relative influence of such factors on the ability of satellite telemetry units to provide the expected amount and quality of data by analyzing data from over 3,000 devices deployed on 62 terrestrial species in 167 projects worldwide. We evaluate the success rate in obtaining GPS fixes as well as in transferring these fixes to the user and we evaluate failure rates. Average fix success and data transfer rates were high and were generally better predicted by species and unit characteristics, while environmental characteristics influenced the variability of performance. However, 48% of the unit deployments ended prematurely, half of them due to technical failure. Nonetheless, this study shows that the performance of satellite telemetry applications has shown improvements over time, and based on our findings, we provide further recommendations for both users and manufacturers.

Untangling the roles of fire, grazing and rainfall on small mammal communities in grassland ecosystems.

In grassland systems across the globe, ecologists have been attempting to understand the complex role of fire, grazing and rainfall in creating habitat heterogeneity and the consequences of anthropogenic control of these factors on ecosystem integrity and functioning. Using a South African grassland ecosystem as a model, we investigated the impact of fire and grazing pressure on small mammal communities during three differing periods of a rainfall cycle. Over 2 years, 15,203 trap nights revealed 1598 captures of 11 species (nine rodents, one macroscelid and one insectivore). Results highlighted the importance of the interplay between factors and showed that the role of fire, grazing and rainfall in determining small mammal abundance was species-dependant. While no two species were affected by the same environmental variables, grass cover or height was important to 56% of species. Considered independently, high rainfall had a positive influence on small mammal abundance and diversity, although the lag period in population response was species-specific. High grazing negatively affected overall abundance, but specifically in Mastomys coucha; fire alone had little immediate impact on small mammal diversity. Six months after the fire, vegetation cover had recovered to similar levels as unburned areas, although small mammal diversity and richness were higher in burned areas than unburned areas. Grazing levels influenced the rate of vegetation recovery. In conclusion, low-level grazing and burning can help to maintain small mammal biodiversity, if conducted under appropriate rainfall levels. A too high grazing pressure, combined with fire, and/or fire conducted under drought conditions can have a negative impact on small mammal biodiversity. To maintain small mammal diversity in grassland ecosystems, the combined effects of the previous year's rainfall and existing population level as well as the inhibition of vegetation recovery via grazing pressure need to be taken into consideration before fire management is applied.

The anesthetic management of triplet cesarean delivery: a retrospective case series of maternal outcomes.

UNLABELLED: Spinal anesthesia for the cesarean delivery of triplets is associated with an increased incidence of maternal hypotension and placental hypoperfusion. We performed a retrospective case series analysis between January 1992 and June 2000 to evaluate the effects of regional anesthetic techniques for cesarean delivery in triplet pregnancies on maternal and neonatal outcome. Spinal and epidural anesthesia were compared with respect to intraoperative hemodynamics and neonatal outcomes. Ninety-six triplet pregnancies were delivered by cesarean section, of which 91 received regional anesthesia. A statistically significant decrease in systolic blood pressure was demonstrated immediately after the induction of spinal as compared with epidural anesthesia. The total volume of IV crystalloid used was significantly larger in the Spinal Anesthesia group. The number of patients receiving more than 15 mg of ephedrine and the cumulative dose of ephedrine was significantly larger in the Spinal group compared with the Epidural group. There were no differences in the rate of perioperative complications between the Spinal and Epidural Anesthesia groups. Neonatal Apgar scores were similar in both groups. The data suggest that both epidural and spinal anesthesia for triplet cesarean delivery are safe techniques, but the latter is associated with a larger initial decrease in systolic blood pressure. This decreasing of systolic blood pressure, however, remained within the physiological range and did not seem to be clinically significant. The need for more crystalloid fluids and ephedrine should be anticipated when spinal anesthesia is used for these cases. IMPLICATIONS: A large retrospective case series of the effects of spinal and epidural anesthesia on maternal hemodynamic profile during cesarean delivery for triplet gestation was performed. Our findings suggest that spinal anesthesia results in outcomes comparable to epidural anesthesia for both mother and newborns.

Gasless laparoscopic cholecystectomy in pregnancy.

Although laparoscopic cholecystectomy has become the surgical procedure of choice for most patients with cholecystitis, the safety of carbon dioxide (CO2) pneumoperitoneum during pregnancy has not been fully elucidated. Pregnancy causes many physiologic changes, resulting in compromised cardiac, pulmonary, and metabolic reserves. The use of CO2 pneumoperitoneum during laparoscopy may cause further physiologic stress to both the parturient and the fetus. A case of gasless laparoscopic cholecystectomy is presented. This procedure avoids potential risks of both absorbed CO2 and increased intraabdominal pressure.

The obstetrical anaesthesia assessment clinic: a review of six years experience.

We reviewed the out-patient consultation notes of 136 pregnant women seen at the Ottawa Civic Hospital from 1985 to 1991 to evaluate the efficacy of an Obstetric Anaesthesia Assessment Clinic (OAC). In addition, their anaesthetic records from labour and delivery were reviewed. For each patient the reason for referral was recorded according to the involved organ system. The anaesthetic management at delivery was compared with the proposed anaesthetic plan by the OAC consultant (obstetric anaesthetist). The majority of women 84 (62%) had complaints related to the musculo-skeletal system. In addition, 18 patients were referred because of previous anaesthetic problems, ten with a history of cardiac disease, and eight with neurological disease. Lumbar epidural analgesia (LEA) was a safe and effective choice for parturients with low back pain, history of lumbar fractures or single level discectomies without lumbar fusion. Parturients with posterior instrumentation experienced an increased incidence of inadequate pain relief from LEA. Individualized anaesthetic management plans were executed for parturients with spina bifida occulta, neurological, cardiac, and haematological disease as well as for women, with a history of adverse drug reactions and previous problems with regional or general anaesthesia. It is concluded that the OAC has provided a valuable service to obstetricians and anaesthetists for the anaesthetic management of pregnant women with co-existing disease. The OAC gave an opportunity for patient education regarding anaesthetic options for labour and delivery. The attending anaesthetist was provided with a risk assessment and anaesthetic management plan which was adhered to with only two exceptions. Finally, the obstetrician was given consistent advice regarding anaesthesia management that may affect obstetrical decisions.

Patient-controlled analgesia with epidural meperidine after elective cesarean section.

BACKGROUND AND OBJECTIVES: We report the first controlled analysis of the use of patient-controlled epidural meperidine. This randomized, prospective study compares the efficacy and safety of patient-controlled epidural meperidine to conventional intramuscular meperidine for the management of postoperative pain after elective cesarean delivery. METHODS: After delivery, 60 patients were randomly assigned to receive either conventional intramuscular meperidine therapy or epidural meperidine by a patient-controlled analgesia pump, which was programmed to deliver bolus doses in addition to a continuous background infusion. RESULTS: Patients in the patient-controlled epidural analgesia group used significantly less meperidine in the first 24 hours after surgery (p < 0.05) and had significantly lower visual analog pain scores (p < 0.05) from three hours postoperatively until study completion at 24 hours. Patients in the patient-controlled epidural analgesia group ambulated sooner (19 +/- 7.8 versus 29.2 +/- 2.2 hours, p < 0.005) and cared for their infants earlier (4.6 +/- 0.9 versus 8.1 +/- 6.8 hours, p < 0.05) than patients receiving intramuscular meperidine. One patient developed a respiratory rate of four breaths per minute, 25 minutes after receiving 75 mg epidural meperidine in the operating room. This was treated with intravenous naloxone. No other serious side effects occurred in either group. Both groups were similar with regard to minor intraoperative and postoperative side effects. CONCLUSIONS: Patient-controlled epidural meperidine after cesarean delivery more effectively manages postoperative pain than conventional intramuscular use. The technique is preferred by both patients and nursing staff and can be used in the ward setting with appropriate organization and education. Respiratory depression, if it occurs, should present early after epidural bolus administration.

Early respiratory depression during caesarean section following epidural meperidine.

A case of respiratory depression which occurred following administration of epidural meperidine during Caesarean section is described. Epidural meperidine, 75 mg (10 mg.ml-1) was given after delivery of the infant to provide postoperative analgesia. Oxygen desaturation (SaO2 90%) and a decrease in respiratory rate (4.min-1) were noted 30 min after epidural meperidine was administered. Naloxone, 0.1 mg, was given iv which resulted in prompt improvement in both respiratory rate and oxygen saturation. Vascular absorption of meperidine from the epidural venous plexus is the most probable explanation for this case of early respiratory depression. We recommend a maximum bolus dose of 50 mg of epidural meperidine for pain management after Caesarean section. It is also important to monitor oxygen saturation continuously during the intraoperative period, and to monitor the patient closely in the recovery room for at least one hour for evidence of respiratory depression.

Sacralization of epidural block with repeated doses of 0.25% bupivacaine during labor.

A descriptive analysis of the progression of epidural block with repeated doses of 0.25% bupivacaine was performed, assessing pain relief (visual analog scoring), dermatomal spread of sensory and motor block, and the associated management and outcome of labor. The influence of epinephrine 1:200,000 on these observations was also assessed by the random assignment of study patients into two groups, one receiving 10 ml of 0.25% bupivacaine plain (n = 28) and another group receiving 10 ml of 0.25% bupivacaine with commercially added epinephrine 1:200,000 (n = 27). Only primigravid patients were studied. Data comparisons were considered significant at p less than 0.05. With repeated doses of 0.25% bupivacaine, administered within fixed dosing intervals of 60-90 minutes, there was an increasing spread of sensory block toward sacral dermatomes while the upper level of sensory block did not change. Sacral sensory analgesia was present in only 3.5% of patients after the first dose of bupivacaine but was evident in 63.2% of patients following the fourth epidural injection. A similar increase in the number of patients with significant motor weakness was also seen as the number of top-up doses increased. A comparison of patients receiving plain solutions and epinephrine containing bupivacaine showed similar demographic profiles between the groups. Both groups received a similar dose of bupivacaine and experienced comparable management and outcome of labor. Epinephrine in a 1:200,000 concentration did not influence the changing characteristics of the epidural block over time. The duration of labor was not significantly different between groups (10.3 +/- 5.2 hours for the plain group and 11.0 +/- 4.7 hours for the epinephrine group).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of lidocaine on regional blood flows and cardiac output in the non-stressed and the stressed foetal lamb.

Lidocaine has been used in obstetrical anaesthesia for many years but there are still concerns about possible adverse affects of this drug on the foetus in utero. To examine in greater detail the effects of lidocaine in the foetus, the following two-part study was done. In Part A, seven pregnant ewes were surgically prepared with maternal and foetal arterial and venous catheters. After recovery from surgery lidocaine was infused intravenously, initially into the ewe and then into both ewe and foetus. Blood lidocaine concentrations were monitored and foetal regional blood flows were determined by the radioactive microsphere method. In Part B, 14 ewes were prepared as in Part A with the addition of an inflatable loop around the umbilical cord. During each study the loop was inflated to partially compress the cord and produce foetal acidosis. In all animals this cord compression was maintained for 30 minutes. In seven animals a lidocaine infusion was given, to examine the effect of lidocaine in the acidotic foetus. Organ blood flows were measured and cardiac outputs calculated. The normal foetuses in Part A showed no change in organ blood flow or cardiac output with arterial lidocaine concentrations of 1.5-3.4 mg X ml-1. In the acidotic foetuses, lidocaine concentrations of 1.4-1.5 mg X ml-1 produced a tachycardia and an increase in cerebral blood flow compared to the control acidotic foetuses. There were no other significant changes. We conclude that arterial lidocaine concentrations of less than 3.5 mg X ml-1 do not produce significant alterations in organ blood flow in normal foetal lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Foetal responses to acute haemorrhage under halothane anaesthesia.

The effect of halothane anaesthesia on the foetal responses to acute haemorrhage was studied in chronically prepared ewes. An average of 27.9 ml X kg-1 of foetal blood was withdrawn resulting in an acute 20 per cent decrease in mean arterial pressure which returned toward the control value after 186 seconds. After the blood loss, cardiac output was reduced by 26.1 per cent and heart rate decreased by 26 per cent. Blood flows to the kidneys, placenta and musculoskeletal structures were reduced by 24.7, 38.2 and 35.3 per cent respectively but flow to the brain increased by 30 per cent. Reinfusion of lost blood, corrected flow reductions and the supply to the gastrointestinal organs increased above control values. This study showed that foetal lambs were able to tolerate an acute blood loss under halothane anaesthesia. An adequate perfusion pressure and blood flow to critical organs, such as the brain was maintained by increasing systemic vascular resistance. The compensation, however, was incomplete. Placental blood flow, maternal-foetal gas exchanges, and redistribution of cardiac output away from gastrointestinal tract and skin were impaired.

The uptake of isoflurane by the foetal lamb in utero: effect on regional blood flow.

Because isoflurane has recently been approved for clinical use in anaesthesia, we have studied the effect of this agent in the foetus using the pregnant ewe as an animal model. Eight pregnant ewes of 120-125 days gestation were surgically prepared with indwelling catheters and tracheostomy. Prior to anaesthesia, labelled microspheres were injected into the foetal circulation to determine cardiac output and regional blood flows to all organs. The ewes were anaesthetized with a constant inspired concentration of 2.0 per cent isoflurane in oxygen. Blood samples were drawn to construct an uptake curve for both mother and foetus. At 60 and 96 minutes of anaesthesia, microspheres were injected into the foetal circulation to measure changes in organ blood flow from the control period. Isoflurane crossed the placenta and appeared in the foetal circulation within two minutes. By 96 minutes, maternal and foetal arterial levels were 116.3 +/- 9.9 and 99.3 +/- 9.1 mEq/L (0.98 vol% and 0.75 vol%). There were no significant changes in foetal blood pressure or pulse rate but foetal pH decreased significantly from 7.39 +/- 0.02 to 7.26 +/- 0.2 (mean +/- SEM) and base excess decreased from -1.1 +/- 1.5 to -6.2 +/- 0.7. Foetal cardiac index decreased from 390.8 +/- 26.9 ml X kg-1 X min-1 to 292.0 +/- 13.8 after 96 minutes of anaesthesia. There were no significant changes in any of the maternal cardiovascular or acid-base parameters.

The effect of halothane anaesthesia on the asphyxiated foetal lamb in utero.

In a previous study, we examined the effects of halothane on the normal foetal lamb in utero. The most significant finding was a 33 per cent fall in foetal mean arterial blood pressure (MABP). Cardiac output and placental blood flow were not affected. To determine if the asphyxiated foetus would respond similarly, the following study was performed. Seven pregnant ewes were surgically prepared two days prior to study with maternal and foetal indwelling arterial and venous cannulas. An inflatable occlusion loop was secured around the umbilical cord. On the day of study, a tracheostomy was performed on each ewe. Microspheres were injected into the foetal circulation during the control period. The occlusion loop was inflated to produce foetal asphyxia and microspheres were again injected. The ewe was then anesthetized with halothane; and after 15 minutes, microspheres were injected into the asphyxiated foetus and halothane levels were measured. The asphyxiated foetuses showed a significant rise in MABP, fall in heart rate and fall in cardiac output from control. Blood flow to the brain was significantly increased and flow to the placenta and gut decreased. Exposure of the asphyxiated foetus to halothane resulted in a fall of MABP to control but no significant change in cardiac output or brain blood flow. The mean halothane level in the foetus was 46.0 mg X l-1 or 0.32 vol%. Exposure of the asphyxiated foetus to halothane for 15 minutes does not produce significant further deterioration of the foetal lamb in utero.