Identification of robust focus measure functions for the automated capturing of focused images from Ziehl-Neelsen stained sputum smear microscopy slide.

Capturing of the best-focused image using focus measure function (FMF) from a stack of images acquired at different focus distances is a crucial step in automatic microscopy development. Detection of bacilli present in Ziehl-Neelsen (ZN) stained sputum smears conventional microscope (CM) images is critical to disease diagnosis. Studies have revealed that the performances of FMFs are sensitive to image contents and background noise. In this article, 24 diverse FMFs were implemented on 31 stacks of CM's field of view images acquired from three different microscopes to determine the best-focused one. Seven FMFs achieved the accuracies of greater than 90%. Accuracy, focus error, and false maxima were calculated for each FMF, and overall score and ranking were also calculated for better interpretation. Preprocessing techniques such as filtering and image distortions (noise, contrast, saturation, illumination, etc.) were performed to evaluate the robustness of every FMF. Gaussian derivative, steerable filters, Tenengrad, and Hemli and Scherer's mean FMFs were identified as the most robust and accurate functions with the accuracy >90%. These FMFs have a relatively less focus error and false maxima rate. Full widths at half maximum of these four FMFs were also computed to determine their efficacy for the optimization process. These four FMFs can be implemented for automated capturing of the image from ZN-stained sputum smear slide. Gaussian derivative FMF can also be used effectively for both CM and fluorescence microscope's field of view image stacks to determine the best-focused one from each stack. © 2017 International Society for Advancement of Cytometry.

MMed cohort supervision: A path out of the swamp?

The authors present the case for collaborative cohort supervision (CCM), including both master's students and novice supervisors, as a possible way to rapidly increase the number of supervisors needed to address the recent implementation of a compulsory research component to specialist registration with the Health Professions Council of South Africa. Different models of CCM are discussed and possible pitfalls highlighted.

The research component of specialist registration--a question of alligators and swamps? A personal view.

The recent implementation of the research requirement for specialist registration presents difficulties with regard to the provision of research supervision, particularly in those medical schools that previously followed the path of qualification via the Colleges of Medicine of South Africa examinations. The differences between the requirements for research supervision as stated in the Health Professions Council of South Africa memorandum and those of the Committee for Higher Education are causing disparities between medical schools similar to those that led to the memorandum in the first place. While the research component of specialist training can only improve the quality of both patient care and academic endeavour, it requires an enormous investment of time on the part of both the specialist trainees and their supervisors. In order to deal with this, specific issues outlined in the article need to be addressed.

Anaesthesia and analgesia for the critically ill parturient.

Anaesthetic and analgesic techniques in the critically ill are determined largely by the nature of the presenting illness. The commonest conditions likely to present as life-threatening emergencies are pre-eclampsia, obstetric haemorrhage, cardiac disease and severe sepsis. Issues dictating choice of anaesthetic technique are the patient's ability to maintain her airway, coagulation status, intravascular volume and haemodynamic dependence upon sympathetic drive, and requirements for ventilatory support and intensive care. Fetal well-being is an issue in the antepartum period, uteroplacental blood flow should be maintained and hypotension avoided. Maternal survival takes priority, however, and occasionally general anaesthetic techniques must be used which lead to neonatal respiratory depression and requirement for ventilatory support. Anaesthesia itself is associated with known hazards. The risks of each technique must be balanced against possible benefits in the context of the presenting illness.

Mivacurium for caesarean section in hypertensive parturients receiving magnesium sulphate therapy.

The interaction between mivacurium and magnesium sulphate was investigated in a group of parturients undergoing caesarean section under general anaesthesia. Thirty parturients were studied; 10 normotensive controls (group NT), 10 hypertensive controls (group HT) and 10 hypertensives who received magnesium sulphate (group HTM). At induction group HT received 30 microg/kg of alfentanil and group HTM 10 microg/kg of alfentanil and 30 or 60 mg/kg of magnesium sulphate. Neuromuscular function was monitored by electromyography. Mivacurium 0.15 mg/kg was given after 60% recovery of T1 following succinylcholine. Magnesium concentrations and plasma cholinesterase activity were significantly elevated in group HTM (1.57 +/- 0.53 mmol/1 and 4.60 +/- 1.27 kU/1) compared with group HT (0.71 +/- 0.18 mmol/1 and 3.44 +/- 0.97 kU/1) and group NT (0.60 +/- 0.07 mmol/1 and 2.86 +/- 0.82 kU/1) (P < 0.005). Time to maximal recovery, and time from 25-75% of maximal recovery from mivacurium, were significantly prolonged in group HTM (60.9 +/- 15.3 min and 16.8 +/- 5.6 min) compared with group HT (34.9 +/- 7.6 min and 7.6 +/- 3.6 min) and group NT (37.4 +/- 14.4 min and 8.5 +/- 3.4 min) (P < 0.01). Time to 25% recovery was prolonged in group HTM (35.1 +/- 7.4 min) compared with the other two groups (HT: 21.6 +/- 6.4 min and NT: 22.8 +/- 10.2 min) (P < 0.01). Whilst the duration of action of mivacurium, determined by electromyography, is prolonged by subtherapeutic serum magnesium concentrations, of the available non-depolarizing relaxants mivacurium would seem to be most appropriate for caesarean section.

Can pulse oximetry detect raised intracompartmental pressure?

Pulse oximetry has been advocated as a simple noninvasive investigation of vascular compromise. Its usefulness in aiding diagnosis of microvascular compromise in a developing compartment syndrome is questioned. This study investigates the reproducibility of pulse oximetry and the effect on arterial haemoglobin saturation of raising limb intracompartmental pressure by compression bandaging. In 32 out of 50 normal subjects there was a difference in percentage saturation between right and left arms, with a 2% difference in 6 people (12%). Percentage saturation fell significantly at average bandage pressures of 80 mmHg (P < 0.0001) and 60 mmHg (P < 0.001). At clinically relevant pressures, the test had a sensitivity of 40.4%. With a greater than 50% risk of a false-negative result, pulse oximetry is not an appropriate additional investigation in the detection of raised intracompartmental pressure.

Municipal solid waste stabilisation by leachate recirculation.

The purpose of this study is to determine the impact of leachate recirculation on stabilisation of municipal solid wastes. The study was carried out by using two lab-scale landfill bioreactors containing approximately 10 kg of waste each, in order to follow waste degradation over 16 weeks of time period. The main difference between anaerobic recirculated and without recirculation bioreactors options is determined in leachate quality. Leachate quality is regularly measured by the means of pH, electrical conductivity, calcium, magnesium, total kjeldahl nitrogen, phosphate and chemical oxygen demand (COD). It has been observed that leachate recirculation is more effective on anaerobic degradation of solid waste than non-recirculated degradation. The leachate recirculated bioreactor appears to be the more effective option in the removal of COD by 89.93% and stabilisation of pH at 7.5. After 16 weeks of anaerobic degradation, waste stabilization seemed to have reached for the recirculated bioreactor. Therefore, further studies are required to determine the optimum operational conditions for leachate recirculation rates, also with the operational costs of recirculation for solid waste stabilisation.

'But it's just a spinal': combating increasing rates of maternal death related to spinal anaesthesia.

The number of women dying as a result of spinal anaesthesia during caesarean section in South Africa is steadily increasing in the triennial reports of the National Committee on Confidential Enquiry into Maternal Deaths (NCCEMD). This article postulates some of the reasons behind this phenomenon. The concern is raised that spinal anaesthesia is being undertaken inappropriately by poorly trained practitioners. A case is made for the rigorous application of known safety standards and for doctors to be appropriately trained in anaesthesia and to be solely responsible for the care of the mother during caesarean section. The need for doctors to be trained and prepared to administer general anaesthesia when required is noted.

First principles based design and experimental evidence for a ZnO-based ferromagnet at room temperature.

The introduction of ferromagnetic order in ZnO results in a transparent piezoelectric ferromagnet and further expands its already wide range of applications into the emerging field of spintronics. Through an analysis of density functional calculations we determine the nature of magnetic interactions for transition metals doped ZnO and develop a physical picture based on hybridization, superexchange, and double exchange that captures chemical trends. We identify a crucial role of defects in the observed weak and preparation sensitive ferromagnetism in ZnO:Mn and ZnO:Co. We predict and explain co-doping of Li and Zn interstitials to both yield ferromagnetism in ZnO:Co, in contrast with earlier insights, and verify it experimentally.

Epidural compared with general anaesthesia for caesarean delivery in conscious women with eclampsia.

OBJECTIVE: To compare retrospectively the outcome of caesarean section under epidural anaesthesia with that of general anaesthesia in "stable" women with eclampsia. DESIGN: Retrospective review. METHOD: Over the five-year study period, there were 533 women with eclampsia and of these 66 women (12.4%), fulfilled the criteria of being 'stable'. Of the 66 women, 37 received epidural, 27 general, and 2 spinal anaesthesia. RESULTS: There were no major complications with either general or epidural anaesthesia. Epidural anaesthesia was associated with higher one-minute Apgar scores. CONCLUSION: This study indicates that both maternal and neonatal outcomes are not affected adversely by the use of epidural anaesthesia in selected cases of eclampsia.

Effects of alfentanil and fentanyl on induction of anaesthesia in patients with severe pregnancy-induced hypertension.

Forty patients with severe pregnancy-induced hypertension presenting for Caesarean section under general anaesthesia were allocated randomly to receive either fentanyl 2.5 micrograms kg-1 or alfentanil 10 micrograms kg-1 as part of the anaesthetic induction sequence. In all patients, the cardiovascular response to tracheal intubation was measured. Both drugs attenuated the response equally but did not abolish it in all patients. Alfentanil 10 micrograms kg-1 is a suitable alternative to fentanyl 2.5 micrograms kg-1 for patients with pregnancy-induced hypertension.

A laboratory assessment of oxygen delivery from a portable chemical generator.

A simple portable chemical oxygen generator was tested in the laboratory. The device is designed for use by the public as an oxygen supply until an emergency team arrives with appropriate oxygen cylinders. The generator was found to supply a mean (SD) flow of oxygen of 3.6 (0.01) l.min-1 for 12.5 (range 12.4-12.6)min. The mean (SD) total volume of oxygen produced was 47(0.17) l. The supplied oxygen mask was a variable performance type with the problems and limitations inherent in this design; an oxygen flow of 8 l.min-1 is required to provide 40% oxygen and most of the oxygen is wasted and not available to the patient. This poses a serious limitation to any device which has a limited capability (in flow and/or total volume) for producing oxygen.

Intravenous administration of the proton pump inhibitor omeprazole reduces the risk of acid aspiration at emergency cesarean section.

This study documented gastric pH and volume, and the number of patients at risk for acid aspiration of gastric contents, in a group of mothers undergoing emergency cesarean section under general anesthesia. Patients were randomized in a double-blind fashion to receive omeprazole 40 mg intravenously or placebo at the time of decision to proceed to cesarean section. In addition, all patients received 10 mg intravenous metoclopramide and 30 mL of 0.3 M sodium citrate. Aspiration of gastric contents was undertaken immediately after endotracheal intubation (PI) and before tracheal extubation (PE). Patients with both pH < 3.5 and volume > 25 mL were deemed to be at risk of acid aspiration should regurgitation occur. Only cases where the study-drug-to-PI-aspiration interval was > 30 min were evaluated. There were 282 patients in the study group and 259 in the control group. PI, 11 patients (4.25%; 95% confidence interval [CI] 1.79-6.71) were at risk in the control group compared with 4 (1.42%; 95% CI 0.04-2.8) in the study group (P = 0.045). The omeprazole-to-PI-aspiration interval in these four cases was < or = 40 min. PE, 19 (7.3%; 95% CI 4.17-10.51) patients were at risk in the control group compared with 2 (0.7%; 95% CI 0-1.69) in the study group (P < 0.0001). Mean pH in patients receiving omeprazole was significantly higher (P < 0.001) than in the control group. Gastric volumes were significantly lower in the omeprazole group compared with the control group at both PI (P = 0.006) and PE (P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Laboratory assessment of a user-assembled oxygen generation kit.

A laboratory assessment was made of a user-assembled oxygen generation kit designed for use in medical emergencies in the community. Twenty-five kits were studied at five different water temperatures and the rate of oxygen generation and its concentration were measured. The apparatus produced a mean (SD) oxygen volume of 37 (1.98) l which was not affected by the starting water temperature. The mean (SD) rate of flow varied from 2.2 (0.04) l.min-1 at 16 degrees C to 10.3 (2.74) l.min-1 at 40 degrees C but the duration of flow varied inversely. Oxygenation concentrations ranging from 30-51% were produced at starting water temperatures from 22 degrees C-40 degrees C, respectively.

Intravenous ranitidine reduces the risk of acid aspiration of gastric contents at emergency cesarean section.

This study documented gastric pH and volume and the number of patients at risk of acid aspiration of gastric contents in a group of mothers undergoing emergency cesarean section under general anesthesia. Patients were randomized in a double-blind fashion to receive ranitidine, 50 mg intravenously, or placebo at the time of decision to proceed to cesarean section. In addition, all patients received 30 mL of 0.3 M sodium citrate on entry into the operating room. Aspiration of gastric contents was undertaken immediately after endotracheal intubation (PI) and before tracheal extubation. Patients with both pH < 3.5 and volume > 25 mL were deemed to be at risk of acid aspiration should regurgitation occur. Postintubation, 12 patients (4%) were at risk in the citrate-alone group and 7 patients (2.3%) were at risk in the ranitidine/citrate group (not significant). Preextubation, 17 patients (5.6%) were at risk in the citrate-alone group and 1 patient (0.3%) was at risk in the ranitidine/citrate group (P < 0.05). PI pH in patients receiving ranitidine/citrate (mean 5.2, SD 0.8) was significantly higher than in patients receiving citrate alone (mean 4.9, SD 1.1). None of the patients who received ranitidine more than 30 min before the PI sample were at risk compared to 6 (3.2%) in the citrate alone group (P = 0.05). We conclude that 50 mg of intravenous ranitidine given at the time of decision to proceed to cesarean section reduces the risk of acid aspiration provided that at least 30 min have elapsed from injection to induction of anesthesia.

Expectant management of early onset of severe pre-eclampsia in Durban.

Fifty patients with severe pre-eclampsia who presented before 32 weeks' gestation were managed conservatively (sedation, bed rest, antihypertensive therapy and intensive fetal and maternal monitoring) until intervention was indicated. Twelve patients presented before 26 weeks of pregnancy and there were no fetal survivors in this group; 23 presented between 26 and 29 weeks and 8(34,8%) of the babies in this group survived. The rate of perinatal loss in those presenting between 30 and 32 weeks was 26,6% (N = 4). Patients who had a history of a hypertensive disorder in their previous pregnancy(ies) had a higher perinatal mortality rate; 23 such mothers experienced 16 perinatal losses compared with 27 mothers who had no such history and who had only 8 perinatal losses. There was 1 maternal death, there were 2 cases of eclampsia, 3 of pulmonary oedema, 4 of abruptio placentae and 1 case of renal failure; 2 patients had disseminated intravascular coagulation. The local indigent and underprivileged black population have a more aggressive form of early onset of severe pre-eclampsia than that reported for other population groups. The high maternal complication rate of 30,8% and the low fetal survival rate before 26 weeks indicate that there is no place in our setting for expectant management of severe pre-eclampsia in patients presenting before 26 weeks. This applies particularly to those with a previous history of hypertension in pregnancy.

Leg elevation and wrapping in the prevention of hypotension following spinal anaesthesia for elective caesarean section.

Ninety-seven parturients undergoing elective Caesarean section were allocated randomly to have their legs elevated to approximately 30 degrees on pillows or elevated and wrapped with elasticated Esmarch bandages or neither (controls) following spinal anaesthesia. All patients received intravenous crystalloid (20 ml.kg-1 over 20 min) prior to spinal injection and were placed in the left lateral tilt position. Significant hypotension was treated with intravenous ephedrine in 5 mg bolus doses. Leg wrapping resulted in a significant reduction in the incidence of postspinal hypotension in comparison to the control group (18% compared to 53%, p = 0.004). This represents a five-fold reduction in the likelihood of postspinal hypotension (odds ratio 5.3, 95% CI 1.7-16.3). Leg elevation alone did not significantly reduce the incidence of hypotension (39%). There was no significant difference in the time of onset of hypotension between the groups. For those patients requiring ephedrine, there was no significant difference in mean dose requirements between the groups. The use of leg compression immediately postspinal provides a simple means of reducing the accompanying hypotension and should be used more widely.

Relative risk analysis of factors associated with difficult intubation in obstetric anesthesia.

Difficult tracheal intubation, often unexpected, has been identified as the commonest contributory factor to anesthetic-related maternal death. The ability to predict such cases preoperatively would be of great value. Preoperative airway assessment and potential risk factors for difficult tracheal intubation were recorded in 1,500 patients undergoing emergency and elective cesarean section under general anesthesia. Airway assessment using a modified Mallampati test recorded oropharyngeal structures visible upon maximal mouth opening. Potential risk factors documented were obesity; short neck; missing, protruding, or single maxillary incisors; receding mandible; facial edema; and swollen tongue. Subsequent to induction of anesthesia, the view at laryngoscopy and difficulty at intubation were graded. There was a significant (P less than 0.001) correlation between the oropharyngeal structures seen and both the veiw at laryngoscopy and difficulty at intubation. Univariate analysis demonstrated a significant association between difficult intubation and short neck (P less than 0.001), obesity (P less than 0.0001), missing maxillary incisors (P less than 0.02), protruding maxillary incisors (P less than 0.001), single maxillary incisor (P less than 0.0001), and receding mandible (P less than 0.003). Neither facial edema (P = 0.414) nor swollen tongue (P = 0.141) were found to be associated with difficult intubation. Multivariate analysis removed obesity and missing and single maxillary incisors as risk factors. Obesity was eliminated because of its strong association with short neck. The probability of experiencing a difficult intubation for various combinations of risk factors was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid administration of crystalloid preload does not decrease the incidence of hypotension after spinal anaesthesia for elective caesarean section.

Twenty parturients undergoing elective Caesarean section were allocated randomly to receive crystalloid preload 20 ml kg-1 over either 20 min or 10 min before spinal anaesthesia. Significant hypotension (systolic arterial pressure less than 100 mm Hg and less than 80% of baseline value) occurred in six of the 10 patients in the 20-min preload group and seven of 10 patients in the 10-min preload group (ns). Both groups had a significant (P less than 0.05) increase in central venous pressure during the preload period. The mean central venous pressure in the 10-min group was 11.9 mm Hg (range 6-19 mm Hg), which was significantly greater (P less than 0.05) than that in the 20-min group (mean 7.3 mm Hg, range 2-13 mm Hg). Three patients in the 10-min group had clinically unacceptable increases in central venous pressure. This study has demonstrated that rapid administration of crystalloid preload before spinal anaesthesia did not decrease the incidence or severity of hypotension, and questions the role of crystalloid preload.

Acute spinal cord injury in pregnancy: an illustrative case and literature review.

Acute trauma is not all that uncommon in pregnancy. It accounts for 15% of non-obstetric maternal deaths. Moreover, about 15% of acute spinal cord injuries involve young women of childbearing age (Gilson et al., 1995). Most of the existing literature on spinal cord injury in pregnancy is concerned with the management of patients with pre-existing lesions; very few articles deal with acute injuries. We report the management of a case of acute spinal cord injury in the third trimester of pregnancy and review the major clinical issues associated with such cases.