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.

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)