Gerard W. Ostheimer Lecture 2006: What’s New in Obstetric Anaesthesia? Contributions from the 2005 literature

The Gerard W. Ostheimer lecture is given every year at the annual meeting of the Society for Obstetric Anesthesia and Perinatology by an obstetric anaesthesiologist who has reviewed the scientific literature for the previous calendar year. This article is based on the 2006 Ostheimer lecture and reviews three areas of interest in neonatology: resuscitation of the newborn, neonatal encephalopathy and the influence of epidural analgesia on breastfeeding.

An outbreak of Aspergillus meningitis following spinal anaesthesia for caesarean section in Sri Lanka: a post-tsunami effect?

An outbreak of Aspergillus fumigatus meningitis occurred in 5 women following spinal anaesthesia, performed between 21 June and 17 July 2005 for caesarean section, in Colombo, Sri Lanka. The patients' median age was 27 years. Different teams in 2 maternity hospitals gave spinal anaesthesia. Mean incubation period was 11.2 days. Fever, headache and nuchal rigidity were common presentations. Remittent fever continued despite broad-spectrum intravenous antibiotics. Papilloedema, lateral rectus palsy, cerebral infarction and haemorrhage developed later. Three patients died. Cerebrospinal fluid pleocytosis with low glucose yielded negative PCR for fungi. Fungal cultures subsequently grew Aspergillus fumigatus. A post-mortem of the first patient confirmed Aspergillus meningitis, followed by treatment with amphotericin B and voriconazole, that saved the lives of others. Visual and hearing impairment in one and complete recovery in the other were observed a year after treatment. Examination of unused plastic syringes, needles, cannulae, and ampoules of anaesthetic agents confirmed that 43 syringes from three different manufactures were contaminated with Aspergillus fumigatus. The stores for drugs and devices of the Ministry of Health were examined and found to be full of tsunami donations, while regular procurements of the Ministry were kept in a poorly maintained humid warehouse. Inadequate space for tsunami donations was identified as the most plausible explanation for sub-optimal storage. Withdrawal and incineration of all unused syringes controlled the outbreak. The survival of those aggressively treated for Aspergillus meningitis suggests in hindsight that the availability of diagnostic tests and specific treatment, and early recognition of the outbreak could have saved the lives of victims who died. Early life-threatening side-effects and permanent long term sequelae of antifungal medication stress the need to be cautious with empirical treatment in immuno-competent low-risk individuals.

Paclitaxel induced apoptosis in breast cancer cells requires cell cycle transit but not Cdc2 activity

PURPOSE

Paclitaxel (PTX) is a widely used chemotherapy agent and may cause cell death by apoptosis subsequent to microtubule (MT) disruption. In this paper, we have investigated whether cell cycle transit and or Cdc2 (Cdk1) activity is required for the apoptosis induced by PTX.

METHODS

Cell cycle was analyzed by flow cytometry, Cdc2 was assayed bio chemically. Cdc2 activity was decreased by siRNA and dominant negative (dn) Cdc2 expression. Cells were arrested by chemical or biological inhibitors in a G1 or S phase. Apoptosis was measured by DNA fragmentation and examination of nuclei by microscopy. JNK and AKT activations were assessed as well.

RESULTS

Cell cycle inhibition was highly effective in decreasing PTX induced apoptosis. MT morphology was not altered by these inhibitors. PTX induced JNK activity or AKT mediated BAD phosphorylation was unaffected by cell cycle inhibitors. Abrogation of Cdc 2 activity was without effect on PTX induced apoptosis.

CONCLUSIONS

While cell cycle transit is required for PTX induced apoptosis; Cdc2 activity is not required.

Hemostatic Function in Healthy Pregnant and Preeclamptic Women: An Assessment Using the Platelet Function Analyzer (PFA-100??) and Thromboelastograph??

BACKGROUND

The PFA-100 is a point-of-care platelet function analyzer which measures the speed of formation of a platelet plug in vitro, expressed as closure time (CT) in seconds. This device could potentially be used to assess primary hemostasis prior to regional anesthesia. In this prospective, observational study we sought to establish 95% reference intervals for PFA-100 and Thromboelastograph (TEG) values for our normal pregnant population, before comparing the PFA and TEG in measuring platelet function in preeclamptic and healthy pregnant women at term, using confidence interval analysis and analysis of variance.

METHODS

Routine hematologic and coagulation tests were performed along with von Willebrand Factor, CT, and TEG measurements. Results are expressed as mean (sd).

RESULTS

Increased severity of preeclampsia was associated with increasing prolongation of CT, even in the presence of normal platelet counts. In severe preeclampsia, the PFA-100 CT (mean (sd): 155 (65) s) exceeded the 95% reference interval of the control group (70-139 s). In contrast, TEG maximum amplitude (MA) in severe preeclampsia (mean (sd): 71 (8) mm) remained within the 95% reference interval for MA in normal pregnancy (64-82 mm).

CONCLUSION

We conclude that impairment of primary hemostatic function with increasing severity of preeclampsia was recorded by the PFA-100 but not the TEG.

Suprasternal Doppler Estimation of Cardiac Output: Standard Versus Sequential Combined Spinal Epidural Anesthesia for Cesarean Delivery

BACKGROUND

Sequential (Seq) combined spinal epidural (CSE) may provide better cardiovascular stability than standard (Std) CSE for cesarean delivery. We compared the cardiovascular stability of both techniques using suprasternal Doppler.

METHODS

Healthy women (n = 40) scheduled for elective cesarean delivery were randomized into two groups; Std or Seq CSE. Serial measures of cardiac output indices, including minute distance, stroke distance, stroke volume, peak velocity, and corrected flow time, were recorded before and after intravascular fluid administration and after CSE. Women received either hyperbaric bupivacaine 10 mg (Std) or 5 mg (Seq) with intrathecal fentanyl 15 microg. An epidural top-up with bupivacaine 0.5% w/v (5 mL at 20 min in the Std group and 10 mL at 15 min followed by 5 mL at 25 min in the Seq group) was given if predefined sensory targets were not met. Data were collected every 5 min after intrathecal injection. Hypotension was treated with ephedrine. Statistical analyses included repeated measures analysis of variance, analysis of covariance and Student's t-test. P < 0.05 denoted significance.

RESULTS

Results showed no difference in cardiac output, minute distance, stroke distance, stroke volume, peak velocity, or corrected flow time between groups over the first 20 min after spinal injection. For whole measurement periods, mean lowest values for these same measures showed no group differences.

CONCLUSION

We therefore found no benefit in terms of cardiovascular stability of Seq to Std CSE for elective cesarean delivery in the healthy pregnant population.

Methods of repair for obstetric anal sphincter injury

BACKGROUND

Anal sphincter injury during childbirth - obstetric anal sphincter injuries (OASIS) - is associated with significant maternal morbidity including perineal pain, dyspareunia and anal incontinence. Anal incontinence affects women psychologically and physically. Many do not seek medical attention because of embarrassment. The two recognised methods for the repair of damaged external anal sphincter (EAS): are end-to-end (approximation) repair and overlap repair.

OBJECTIVES

To compare the effectiveness of overlap repair versus end-to-end repair following OASIS in reducing subsequent anal incontinence, perineal pain, dyspareunia and improving quality of life.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 January 2006), MEDLINE (January 1966 to 31 January 2006), EMBASE (January 1974 to 31 January 2006), SciSearch (January 1974 to 31 January 2006) and conference proceedings of obstetrics and gynaecology, surgery and coloproctology.

SELECTION CRITERIA

Randomised controlled trials comparing different techniques of immediate primary repair of EAS following OASIS.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed independently by all authors.

MAIN RESULTS

Three eligible trials, of grade A quality, involving 279 women, were included. There was considerable heterogeneity in the outcome measures, time points and reported results. Meta-analyses showed that there was no statistically significant difference in perineal pain (relative risk (RR) 0.08, 95% confidence interval (CI) 0.00 to 1.45, one trial, 52 women), dyspareunia (RR 0.62, 95% CI 0.11 to 3.39, one trial, 52 women), flatus incontinence (RR 0.93, 95% CI 0.26 to 3.31, one trial, 52 women) and faecal incontinence (RR 0.07, 95% CI 0.00 to 1.21, one trial, 52 women) between the two repair techniques at 12 months but showed a statistically significantly lower incidence in faecal urgency (RR 0.12, 95% CI 0.02 to 0.86, one trial, 52 women) and lower anal incontinence score (weighted mean difference -1.70, 95% CI -3.03 to -0.37) in the overlap group. Overlap technique was also associated with a statistically significant lower risk of deterioration of anal incontinence symptoms over 12 months (RR 0.26, 95% CI 0.09 to 0.79, one trial, 41 women). There was no significant difference in quality of life.

AUTHORS' CONCLUSIONS

The limited data available show that compared to immediate primary end-to-end repair of OASIS, early primary overlap repair appears to be associated with lower risks for faecal urgency and anal incontinence symptoms. As the experience of the surgeon is not addressed in the three studies reviewed, it woudl be inappropriate to recommend one type of repair in favour of another.

The effects of biocides (antiseptics and disinfectants) on the endospores ofRhinosporidium seeberi

No data exists on the activity of biocides (antiseptics and disinfectants) on Rhinosporidium seeberi that causes rhinosporidiosis in humans and animals. On account of the inability to culture R. seeberi, in vitro, dyes were used to assess the morphological integrity and viability of biocide-treated endospores that are considered to be the infective stage of this pathogen. Evan's Blue (EvB) identifies the morphological integrity of the endospores while MTT (3-[4, 5-dimethylthiazol-2yl]-2, 5-diphenyl tetrazolium bromide) identifies metabolic activity through its reduction by cellular dehydrogenases to microscopically visible deposits of insoluble formazan. MTT-negativity has earlier been shown to correlate with absence of growth of yeast and mycelial fungi in culture and could thus indicate the loss of viability of MTT-negative rhinosporidial endospores. Hydrogen peroxide, glutaraldehyde, chloroxylenol, chlorhexidine, cetrimide, thimerosal, 70% ethanol, iodine in 70% ethanol, 10% formalin, povidone-iodine, sodium azide and silver nitrate were tested on freshly-harvested endospores and all biocides caused metabolic inactivation with or without altered structural integrity as shown by absence of MTT-staining after 3, 24 or 36 hour after exposure, while EvB stained only the endospores treated with sodium azide, ethanol, thimerosal, chloroxylenol, glutaraldehyde and hydrogen peroxide. With clinically useful biocides - chlorhexidine, cetrimide-chlorhexidine, 70% ethanol, povidone-iodine and silver nitrate, a total period of exposure of endospores to the biocide, for seven minutes, produced metabolic inactivation of the endospores. Anti-rhinosporidial antiseptics that could be used in surgery on rhinosporidial patients include povidone-iodine in nasal packs for nasal and naso-pharyngeal surgery, chlorhexidine and cetrimide-chlorhexidine on the skin, while povidone-iodine and silver nitrate could have application in ocular rhinosporidiosis.

Computed tomography pseudofractures of the mid face and skull base

Thin-section multislice CT delineates numerous normal skull-base and mid-facial bony discontinuities. These represent sutures, fissures and neurovascular foramina or channels, and should be differentiated from fractures. This pictorial review describes and illustrates the characteristic location and multiplanar CT appearances of these structures. Their clinical significance in terms of pathological processes and surgical planning are discussed.

The Effect of Posture and Baricity on the Spread of Intrathecal Bupivacaine for Elective Cesarean Delivery

Posture and baricity during induction of spinal anesthesia with intrathecal drugs are believed to be important in determining spread within the cerebrospinal fluid. In this double-blind prospective study, 150 patients undergoing elective cesarean delivery were randomized to receive a hyperbaric, isobaric, or hypobaric intrathecal solution of 10 mg bupivacaine during spinal anesthesia induced in either the sitting or right lateral position. After an intrathecal injection using a combined-spinal technique patients were placed in the supine wedged position. We determined the densities of the three intrathecal solutions from a previously validated formula and measured using a DMA-450 density meter. Data collection included sensory level, motor block, episodes of hypotension, and ephedrine use. Statistical analysis included analysis of variance and Cuzick's trend. In the lateral position, baricity had no effect on the spread of sensory levels for bupivacaine compared to the sitting position, where there was a statistically significant difference in spread with the hypobaric solution producing higher levels of analgesia than the hyperbaric solution (P = 0.002). However, the overall differences in maximal spread only differed by one dermatome, with the hyperbaric solution achieving a median maximum sensory level to T3 compared with T2 for the isobaric and hypobaric solutions. Motor block was significantly (P = 0.029) reduced with increasing baricity and this trend was significant (P = 0.033) for the lateral position only. Hypotension incidence and ephedrine use increased with decreasing baricity (P = 0.003 and 0.004 respectively), with the hypobaric sitting group having the most frequent incidence of hypotension (76%) as well as cervical blocks (24%; P = 0.032).

The angiotensin IV/AT4 receptor

The angiotensin AT(4) receptor was originally defined as the specific, high-affinity binding site for the hexapeptide angiotensin IV (Ang IV). Subsequently, the peptide LVV-hemorphin 7 was also demonstrated to be a bioactive ligand of the AT(4) receptor. Central administration of Ang IV, its analogues or LVV-hemorphin 7 markedly enhance learning and memory in normal rodents and reverse memory deficits observed in animal models of amnesia. The AT(4) receptor has a broad distribution and is found in a range of tissues, including the adrenal gland, kidney, lung and heart. In the kidney Ang IV increases renal cortical blood flow and decreases Na(+) transport in isolated renal proximal tubules. The AT(4) receptor has recently been identified as the transmembrane enzyme, insulin-regulated membrane aminopeptidase (IRAP). IRAP is a type II integral membrane spanning protein belonging to the M1 family of aminopeptidases and is predominantly found in GLUT4 vesicles in insulin-responsive cells. Three hypotheses for the memory-potentiating effects of the AT(4) receptor/IRAP ligands, Ang IV and LVV-hemorphin 7, are proposed: (i) acting as potent inhibitors of IRAP, they may prolong the action of endogenous promnestic peptides; (ii) they may modulate glucose uptake by modulating trafficking of GLUT4; (iii) IRAP may act as a receptor, transducing the signal initiated by ligand binding to its C-terminal domain to the intracellular domain that interacts with several cytoplasmic proteins.

Regulation of lipoprotein trafficking in the kidney: role of inflammatory mediators and transcription factors

Inflammation and dyslipidaemia both play important roles in the development of glomerular atherosclerosis in renal diseases. We have demonstrated that inflammatory mediators induced Scr (scavenger receptor) expression and the formation of foam cells, and that AP-1 (activator protein 1)/ets were necessary transcriptional factors for Scr induction in HMCs (human kidney mesangial cells). Most cells are protected from excessive native LDL (low-density lipoprotein) accumulation by tight feedback regulation of the LDLr (LDL receptor). However, we observed that HMCs formed foam cells via the LDLr pathway when incubated with IL-1β (interleukin-1β; 5 ng/ml) and unmodified LDL (200 μg/ml), suggesting that inflammatory mediators may disrupt the cholesterol-mediated feedback regulation. This feedback involves cholesterol-mediated down-regulation of LDLr controlled by SCAP [SREBP (sterol responsive element-binding protein) cleavage-activating protein]. We have also demonstrated that both tumour necrosis factor α and IL-1β increased nuclear SREBP-1 levels by increasing SCAP mRNA expression, even in the presence of a high concentration of LDL. Since intracellular lipid content is governed by both influx and efflux mechanisms, we set out to examine the impact of inflammatory cytokines on cholesterol efflux, a process mediated by the protein ABCA1 (ATP binding cassette A1). IL-1β inhibited [3H]cholesterol efflux from HMCs by inhibition of the peroxisome-proliferator-activated receptor/LXR (liver X receptor)/ABCA1 pathway. Taken together, our results suggest that inflammatory mediators increase lipid accumulation in HMCs not only by promoting increased lipoprotein uptake by Scr and LDLr, but also by inhibiting ABCA1-mediated cholesterol efflux to high-density lipoprotein.

A study of the investigation of death (coroner system) in Sri Lanka

Sri Lanka (Ceylon) inherited the 'coroner system' of investigating death in the early nineteenth century. Unlike in England and Wales, the coroner system in Sri Lanka did not change much in the last century. This study, the first of its kind, was performed for a period of three months in 1995 to analyse the causes and circumstances of deaths reported for inquest, and the number of autopsies performed. Of the 868 cases reported to the Inquirer, the circumstances were not determined in 94 cases at the initial inquest proceedings. Of the other 774 cases, 454 (58.7%) were natural deaths. Autopsies were performed on 44.5% of natural deaths, 58.2% of accidental deaths, 96% of road traffic accidents, 44.9% of suicides and 81.6% of homicides. Coronary heart disease was the leading cause of natural death (33.9%). Head injuries were responsible for 31.8% of accidental deaths while burns accounted for 24.5% of accidental deaths and 46.3% of suicides. There were 38 cases (4.9%) of homicide of which autopsies were performed in 31. There is an urgent need to reform the century-old laws relating to inquest procedures in the country.

Protein kinase-dependent phosphorylation of the Menkes copper P-type ATPase

The Menkes copper-translocating P-type ATPase (ATP7A; MNK) is a key regulator of copper homeostasis in humans. It has a dual role in supplying copper to essential cuproenzymes in the trans-Golgi network (TGN) and effluxing copper from the cell. These functions are achieved through copper-regulated trafficking of MNK between the TGN and the plasma membrane. However, the exact mechanism(s) which regulate the localisation and biochemical functions of MNK are still unknown. Here we investigated copper-dependent phosphorylation of MNK by a putative protein kinase(s). We found that in the presence of elevated copper there was a substantial increase in phosphorylation of the wild-type MNK in vivo. The majority of copper-dependent phosphorylation was on serine residues in two phosphopeptides. In contrast, there was no up-regulation of phosphorylation of a non-trafficking MNK mutant with mutated cytosolic copper-binding sites. Our findings suggest a potentially important role of kinase-dependent phosphorylation in the regulation of function of the MNK protein.

Postural stability following ambulatory regional analgesia for labor

BACKGROUND

The safety of mobilization following low-dose regional analgesia in parturients remains controversial. Previous studies have demonstrated preserved balance function despite clinically elicited sensory deficits. The aim of this study was to use the Balance Master 6.1, a device capable of real-time analysis of ambulation, to score the performance of basic maneuvers following initiation of low-dose combined spinal-epidural analgesia in laboring women compared with pregnant and nonpregnant controls.

METHODS

Using the Balance Master, balance function during the performance of several simple tasks, including walking and standing up from a sitting position, was evaluated in a prospective, controlled, observational study with 50 laboring women after combined spinal-epidural analgesia compared with 50 pregnant and 50 nonpregnant controls.

RESULTS

Nonpregnant women scored significantly better results in 6 of the 13 measured balance function parameters compared with both the combined spinal-epidural and pregnant control groups. Compared with the nonpregnant subjects, the pregnant groups generated less force standing up from the sitting position (P < 0.0001), walked more slowly (P = 0.0067), and took shorter steps (P < 0.0001). They also took longer to step up onto and over a 20-cm-high obstacle (P < 0.0001), and they generated less force while stepping up. Initial spinal analgesia in laboring women did not significantly affect performance in comparison to the pregnant controls. Thirty-four percent of women in the combined spinal-epidural group required supplemental epidural analgesia following the initial spinal injection (n = 17) before testing; they had significantly impaired balance function in four tests compared with those receiving a spinal injection only (n = 33).

CONCLUSIONS

Being pregnant at term significantly affects balance function, although initial low-dose spinal-epidural analgesia does not impair function further. Subsequent supplemental epidural analgesia may have a detrimental effect on balance, but properly designed studies are awaited to confirm this. This study supports the practice of allowing laboring women with initial low-dose spinal-epidural analgesia to ambulate, but indicates that further studies need to be conducted on the effects of subsequent epidural supplementation.

Predicting the density of bupivacaine and bupivacaine-opioid combinations

IMPLICATIONS

Manipulating the density of local anesthetic solutions by using a simple formula may be clinically useful in producing optimal density solutions for spinal anesthesia under a variety of clinical conditions.

Cell-mediated immune responses (CMIR) in human rhinosporidiosis

Cell mediated immune responses (CMIR) to Rhinosporidium seeberi in human patients with rhinosporidiosis have been studied. With immuno-histochemistry, the cell infiltration patterns in rhinosporidial tissues from 7 patients were similar. The mixed cell infiltrate consisted of many plasma cells, fewer CD68+ macrophages, a population of CD3+ T lymphocytes, and CD56/57+ NK lymphocytes which were positive for CD3 as well. CD4+ T helper cells were scarce. CD8+ suppressor/cytotoxic-cytolytic cells were numerous. Most of the CD8+ cells were TIA1+ and therefore of the cytotoxic subtype. CD8+ T cells were not sub-typed according to their cytokine profile; 1L2, IFN-gamma (Tcl); IL4, ILS (Tc2). In lympho-proliferative response (LPR) assays in vitro, lymphocytes from rhinosporidial patients showed stimulatory responses to Con A but lymphocytes from some patients showed significantly diminished responses to rhinosporidial extracts as compared with unstimulated cells or cells stimulated by Con A, indicating suppressor immune responses in rhinosporidiosis. The overall stimulatory responses with Con A suggested that the rhinosporidial lymphocytes were not non-specifically anergic although comparisons of depressed LPR of rhinosporidial lymphocytes from individual patients, to rhinosporidial antigen with those to Con A, did not reveal a clear indication as to whether the depression was antigen specific or non-specific. The intensity of depression of the LPR in rhinosporidial patients bore no relation to the site, duration, or the number of lesions or whether the disease was localized or disseminated. Rhinosporidial extracts showed stimulatory activity on normal control lymphocytes, perhaps indicating mitogenic activity. These results indicate that CMIR develops in human rhinosporidiosis, while suppressed responses are also induced.

Disposition of inhaled mercury vapor in pregnant rats: maternal toxicity and effects on developmental outcome

The disposition and toxicity of inhaled elemental mercury (Hg0) vapor for pregnant Long-Evans rats, and potential adverse effects on reproductive outcome were investigated. Rats were exposed to 0, 1, 2, 4, or 8 mg Hg0/m(3) for 2 h/day from gestation day (GD) 6 through GD 15. Maternal toxicity occurred primarily in rats exposed to 4 and 8 mg/m(3) and was manifested as a concentration-related decrease in body weight gain and mild nephrotoxicity. Control rats gained about 13% of their initial body weight during the 10-day exposure. Rats exposed to 4 mg/m(3) Hg0 gained about 7% less than controls, and rats exposed to 8 mg/m(3) Hg0 lost about 17% of their initial body weight during the 10-day exposure period. Maternal kidney weights were significantly increased in the 4 and 8 mg/m(3) concentration groups, and urinalysis revealed increased levels of protein and alkaline phosphatase activity in urine of all Hg0-exposed rats. Dams exposed to 8 mg/m(3) were euthanized in moribund condition on postnatal day (PND) 1. There was no histopathological evidence of toxicity in maternal lung, liver, or kidney of exposed rats at GD 6, GD 15, or PND 1. The incidence of resorptions was significantly increased, litter size and PND 1 neonatal body weights were significantly decreased only in the 8-mg/m(3) group. Total Hg concentrations in maternal tissues increased with increasing number of exposure days and concentration. In general, approximately 70% of Hg was eliminated from maternal tissues during the week following the last exposure (GD 15 to PND 1). Elimination of Hg from maternal brain and kidney was slower than in other tissues, possibly due to higher levels of metallothionein. Total Hg concentrations in fetal tissues increased with increasing number of exposure days and concentration, demonstrating that a significant amount of Hg crossed the placenta. One week after the last exposure, significant amounts of Hg were still present in brain, liver, and kidney of PND 1 neonates. Metallothionein levels in neonatal tissues were not significantly increased by exposure to 4 mg/m(3) Hg0. The total amount of Hg in neonatal brain (ng/brain) continued to increase after termination of inhalation exposure, suggesting a redistribution of Hg from the dam to neonatal brain. These data demonstrate that inhaled Hg0 vapor is distributed to all maternal and fetal tissues in a dose-dependent manner. Adverse effects of Hg on developmental outcome occurred only at a concentration that caused maternal toxicity.

Primary endodermal sinus (yolk sac) tumour of the liver

Primary endodermal sinus tumour of the liver is an extremely rare neoplasm. A 37-year-old man presented with a mass in the left lobe of the liver and a raised serum alpha-fetoprotein concentration. A left hepatic lobectomy was performed. Histological examination revealed an endodermal sinus tumour of the liver. There was no evidence of an extrahepatic primary source.