Central venous oxygen saturation during high-risk general surgical procedures-relationship to complications and clinical outcomes.

Major non-cardiac surgery is associated with postoperative morbidity, and perioperative central venous oxygen saturation (ScvO2) may be a predictor of morbidity. This pilot study aimed to define intraoperative ScvO2 and to identify factors associated with postoperative complications. ScvO2 (reflection spectrophotometry) was recorded continuously in a convenience sample of adults undergoing high-risk general surgery. Demographics, intraoperative management, surgery duration, postoperative complications and deaths within 28 days were recorded. Data from 51 patients were analysed. Two (4%) died and 24 (47%) had at least one complication (range 1 to 5). The hospital length-of-stay and duration of surgery were longer in those with complications (22.1±6.1 versus 9.6±3.6 days, P >0.0001, and 328±162 minutes versus 241±94 minutes, P=0.02, respectively). Overall, the ScvO2 was 82±8% and ranged from 40% to 97% with 17 (33%) patients having at least one episode of ScvO2 >70%. Hospital length-of-stay (P >0.0001), time ScvO2 >90% (P=0.003), surgery duration (P=0.005) and blood loss (P=0.02) were correlated with the number of complications. Using multivariate analysis, surgery duration (odds ratio 1.008 [95% confidence interval 1.002 to 1.013]; P=0.006) and change in oxygen extraction ratio (O2ER) at the end of surgery compared to the beginning (odds ratio 1.13 [95% confidence interval 1.001 to 1.28]; P=0.04) were independently associated with complications. The surgery duration and an increased O2ER are factors related to the development of postoperative complications.

Sedation and delirium in the intensive care unit: an Australian and New Zealand perspective.

A survey was conducted to determine sedation and delirium practices in Australian and New Zealand intensive care units. The survey was in two parts, comprising an online survey of reported sedation and delirium management (unit survey) and a collection of de-identified data about each patient in a unit at a given time on a specified day (patient snapshot survey). All intensive care units throughout Australia and New Zealand were invited by email to participate in the survey. Twenty-three predominantly metropolitan, level III Australian and New Zealand intensive care units treating adult patients participated. Written sedation policies were in place in 48% of units, while an additional 44% of units reported having informal sedation policies. Seventy percent of units routinely used a sedation scale. In contrast, only 9% of units routinely used a delirium scale. Continuous intravenous infusion is the primary means of patient sedation (74% of units). While 30% of units reported routinely interrupting sedation, only 10% of sedated patients in the snapshot survey had had their sedation interrupted in the preceding 12 hours. Oversedation appears to be common (46% of patients with completed sedation scales). Use of neuromuscular blockade is low (10%) compared to other published studies. Midazolam and propofol were the most frequently used sedatives. The proportion of patients developing delirium was 21% of assessable patients. Failed and self-extubation rates were low: 3.2% and 0.5% respectively. In Australian and New Zealand intensive care units, routine use of sedation scales is common but not universal, while routine delirium assessment is rare. The use of a sedation protocol is valuable and should be encouraged.

Replication of equid herpesvirus-1 (EHV-1) in the testes and epididymides of ponies and venereal shedding of infectious virus.

Six Welsh Mountain pony colts were infected intranasally with the Ab4 isolate of EHV-1. Clinical and virological monitoring demonstrated mild upper respiratory tract disease, with nasal shedding of virus and establishment of a cell-associated viraemia. Detailed pathological examination of the urogenital tract was performed post mortem on days 4-9 post-infection (PI). EHV-1 was isolated from the epididymis on day 8 and the testis on day 9 PI, with viral replication in endothelial cells of these organs and an associated necrotizing vasculitis and thrombosis. Productive viral infection of germinal epithelium was not observed. In a further study, three Welsh Mountain pony stallions were infected intranasally with Ab4, which again resulted in mild upper respiratory tract disease and the establishment of a cell-associated viraemia. Semen samples were collected up to day 60 PI. Two stallions showed a decrease in the proportion of morphologically normal sperm. Significant numbers of inflammatory cells were observed in the sperm-rich fraction of ejaculates collected from one stallion between days 16 and 28 PI; infectious virus was recovered from the semen of this animal between days 17 and 25 PI, after the cessation of viraemia. The affected stallion appeared clinically normal over the period of venereal EHV-1 shedding.

Replication of equid herpesvirus-1 in the vaginal tunics of colts following local inoculation.

Equid herpesvirus-1 (EHV-1; Ab4 isolate) was inoculated unilaterally into the cavum vaginale of four pony colts under general anaesthesia. The animals were monitored daily for evidence of scrotal or testicular swelling and euthanased electively on days 3, 4, 6 and 12 after infection. Detailed pathological examination of the male genital tract was carried out. In animals examined at days 3 and 4 after infection, replication of EHV-1 was detected bilaterally in mesothelial and endothelial cells of the parietal and visceral vaginal tunics. The mesothelial infection had resolved by day 12 after infection, with no evidence of direct extension to deeper genital organs. None of the four colts showed significant scrotal or testicular swelling.

The effects of continuous treatment of stallions with high levels of a potent GnRH analogue.

The effect of long-term treatment of stallions with a powerful gonadotrophin-releasing hormone (GnRH) analogue was investigated. In the first part of the study, 9 sexually mature pony stallions were allocated to 1 of 3 groups, each of which was treated with 240 micrograms or 60 micrograms Buserelin per day administered by subcutaneously sited osmotic pumps or 30-50 micrograms Buserelin per day via solid, slow-release implants injected subcutaneously. Peripheral blood plasma and serum samples were collected frequently and assayed for follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and testosterone. No significant differences were seen between either high of low dose rates: in all treatment groups, serum and plasma concentrations of FSH, LH and testosterone rose sharply following insertion of pumps ofr implant. The levels remained elevated for 3-10 days in most animals, after which they returned to pre-treatment of lower values. In a second experiment, single implants, formulated to deliver 120 micrograms Buserelin per day for 28 days, were injected subcutaneously in to 2 pony stallions on 4 occasions at 5-day intervals. Gonadotrophin and testosterone secretions were temporarily stimulated in response to the first implant, but thereafter returned to pre-treatment or lower levels and showed no further stimulation following injection of subsequent implants. In a third experiment designed to establish the effects on libido and spermatogenesis of chronic treatment with levels of Buserelin (shown previously to depress gonadotrophin concentrations in stallions), 3 fertile pony stallions received subcutaneous implants at 2- to 5-week intervals for 12 months. Three untreated pony stallions acted as controls. Weekly blood samples were collected from both groups to monitor levels of FSH, LH, testosterone and oestrone sulphate. Semen was collected daily for 6-10 days both before treatment and at 3-month intervals thereafter in order to establish daily sperm output (DSO) and assess libido. Gonadotrophin, testosterone and oestrone sulphate levels were all lower in the treated group compared with either pre-treatment or control values. DSO was reduced by at least 50% throughout the treatment period in treated stallions but 7 months after insertion of the last implant it had returned to pre-treatment values. No significant effects on other semen characteristics were noted and there were no noticeable changes in libido of treated animals throughout the period of the experiment.

Variations in structural and functional changes of stallion spermatozoa in response to calcium ionophore A23187.

Three experiments were conducted to assess the structural and functional changes of stallion spermatozoa in response to the calcium ionophore A23187, and to determine individual variation between stallions. In Experiment 1, changes in the acrosome of spermatozoa exposed to 7.14 microM A23187 for fixed times between 0 and 120 min were examined. There was a steady increase with time in the number of spermatozoa undergoing the acrosome reaction although the rate of increase differed between stallions. Sperm motility decreased sharply when incubation was extended beyond 30 min. In Experiment 2, the ability of ionophore-treated spermatozoa to penetrate zona-free hamster eggs was tested. Percent penetration rates were 75, 50, 28, 27 and 15 for the 5 stallions although the number of swollen sperm heads per penetrated egg (1.7-2.5) did not differ significantly between the stallions. In Experiment 3, the ability of stallion spermatozoa to fertilize zona-intact follicular horse eggs matured in vitro was tested. Semen samples from the 2 stallions that provided the highest and lowest percent acrosome-reacted spermatozoa in Experiment 1, and the highest and lowest penetration rates in Experiment 2, were separated from seminal plasma and treated with 5 microM A23187 for 10 min. The spermatozoa were then washed once and co-incubated with the eggs at 38.5 degrees C for 12-16 h. Swollen sperm heads with associated tails from 1 stallion were found in 8 of 46 eggs fixed after 12-16 h incubation, whereas the corresponding figure for the other stallion was 0/30. It was concluded that considerable individual variation occurs between stallions in the morphological and functional changes exhibited by their spermatozoa in response to treatment with ionophore A23187.

Acrosome reaction of stallion spermatozoa evaluated with monoclonal antibody and zona-free hamster eggs.

The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 +/- 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up to 12 hours in TALP medium maintained motility and exhibited a significant progressive loss of acrosomes as detected by immunofluorescence. Alternatively, a similar loss of acrosomes could be induced with calcium ionophore A23187 over a 90 minute incubation. Ultrastructural observations and incubation with zona-free hamster eggs indicated that only with ionophore treatment was immunofluorescent acrosome loss correlated with a physiological acrosome reaction, while prolonged sperm incubation led to degenerative membrane changes. It was concluded that, if carefully validated, immunofluorescent localization of the acrosome of stallion sperm with monoclonal antibody could be used to monitor the acrosome reaction. Furthermore, definitive acrosome visualization would be valuable in assessing semen quality.

In vitro fertilization of horse follicular oocytes matured in vitro.

In vitro fertilizing ability of stallion spermatozoa was assessed using horse follicular oocytes matured in vitro. After collection, stallion spermatozoa were either: 1) washed and incubated in TALP medium with 3 mg/ml bovine serum albumin (BSA) and 10 micrograms/ml heparin for 4h, 2) washed and incubated in TALP with 3 mg/ml BSA for 3 h and cultured for a further 1 h with 1 mM caffeine and 5 mM dbcAMP, 3) washed and incubated in TALP medium with 3 mg/ml BSA at pH 7.9-8.2 for 2-4 h, or 4) diluted and incubated in TALP medium with 10 mg/ml BSA and 7.14 microM calcium ionophore A 23187 for 5-10 min followed by washing. After a given pretreatment, suspensions were diluted into B2 medium to a concentration of 5 x 10(6) sperm/ml and co-incubated with oocytes for 12 h or 24-48 h. In the ionophore-treated group, 18 of 54 oocytes (33%) were fertilized by 12 h, and 11 of 45 (24%) cleaved by 24-48 h. Evidence of fertilization was not found in the oocytes incubated with spermatozoa from other treatment procedures.

Successful transfer of the embryos of Przewalski's horses (Equus przewalskii) and Grant's zebra (E. burchelli) to domestic mares (E. caballus).

Blastocysts were collected non-surgically from 2 Przewalski's horse and 2 Grant's zebra mares and transferred extra-specifically to domestic horse and donkey recipients. Nine Przewalski's horse embryos were transferred surgically, and 2 non-surgically, to domestic Welsh-type pony mares. After surgical transfer, 7 (77.8%) pregnancies were established and 4 foals were born. Twelve Grant's zebra embryos were transferred surgically to 5 pony and 7 domestic donkey recipients respectively and 1 non-surgically to a donkey; 3 (60%) zebra-in-horse pregnancies were established and 2 went to term. Only 2 (28.6%) zebra-in-donkey pregnancies were established but neither went to term, although one zebra foal was aborted alive at Day 292 but failed to survive. No pregnancies resulted from the non-surgical transfers. Measurement of chorionic gonadotrophin concentrations and parental-specific lymphocytotoxic antibodies in the serum of the recipient animals indicated a pronounced maternal immunological response to the extra-specific embryo, but this could not be correlated with success or failure of pregnancy. The results indicate that extra-specific embryo transfer may be a useful aid to breeding exotic equids in captivity.

Extraspecific donkey-in-horse pregnancy as a model of early fetal death.

Transfer of donkey embryos to horse mares provides a useful model of early fetal death. Endometrial cups do not develop in this one type of extraspecific pregnancy and 80% of donkey fetuses are aborted between Days 80 and 100 of gestation in conjunction with abnormal implantation and an intense accumulation of leucocytes in the endometrium of the surrogate mare. Treatment of mares carrying donkey conceptuses with progestagen (allyl trenbolone) or purified horse chorionic gonadotrophin does not prevent abortion. However, passive immunization with serum from mares carrying intraspecific horse fetuses, or active immunization with donkey lymphocytes, causes a marked increase in fetal survival rate and the birth of live foals. Furthermore, both cytotoxic (rejection type) and immunoprotective maternal immune responses to the xenogeneic donkey fetus can be recalled in mares carrying repeated donkey-in-horse pregnancies. We suggest that the endometrial cup reaction in normal equine pregnancy provides a vital and temporally important antigenic stimulus which results in the mare mounting an immunoprotective response towards her allogeneic fetus in utero.

Distribution of spermatozoa in the mare's oviduct.

The morphology of the uterotubal junction (UTJ) and caudal isthmus during the peri-ovulatory period, and the distribution of spermatozoa within the region, were studied in 10 Pony mares. The proximal tip of the uterine horn and caudal 1-2 cm of the isthmus were removed during oestrus or shortly after ovulation from animals mated or artificially inseminated within the previous 24 h. The tissues were incised longitudinally and fixed for scanning electron microscopy. Analysis of micrographs showed deep longitudinal and oedematous folds in the preovulatory samples. After ovulation, much of the folding and oedema disappeared. There was a regional arrangement of ciliated and nonciliated cells and the cilia showed evidence of directional orientation. Occasional spermatozoa were seen in some specimens deep in furrows between folds of the UTJ.

Deep freezing of horse embryos.

Fourteen horse embryos recovered non-surgically on Days 6-8 after ovulation (Day 0) were cooled slowly to - 35 degrees C (7 embryos) or - 40 degrees C (7 embryos) and stored in liquid nitrogen (- 196 degrees C) for 4-98 days. Surgical transfer of the thawed embryos to unmated recipient mares that had ovulated - 2 to + 1 days with respect to the embryo donors resulted initially in the establishment of 4 conceptuses. However, only one mare maintained her pregnancy to term.