Rheological characteristics of faecal sludge from VIP latrines and implications on pit emptying.

This work aims at characterizing the rheological properties of faecal sludge from Ventilated Improved Pit (VIP) latrines and their implication on pit emptying. Faecal sludge was sampled from 3 pit latrines located in the eThekwini Municipality (Durban, South Africa). Samples were taken at different positions within the pit. For each of the samples, measurements in the rheometer in triplicates were performed in order to determine their rheological properties, and their moisture and ash content were measured also in triplicates. Experiments in the rheometer were performed for samples for which its moisture content was modified. In order to better understand the influence of water addition into the pit. During pit emptying, calculations were carried out from the experimental data, based in the criteria set in the Omni-Ingestor initiative, carried out by the Bill & Melinda Gates Foundation. Faecal sludge exhibited a shear thinning behaviour, i.e. a decrease in viscosity with increasing shear rate, and presented a yield stress comprised between 500 to 1000 Pa. This needs to be surpassed in order to overcome the elastic resistance of the sludge to flow. Similar viscosities were found for the samples from the different pits, irrespective of the position within the pit, except for the sample from the bottom of one of the pits for which it was not possible to induce a flow. This sample had a considerably lower moisture content (67% wet basis) compared to the other samples (around 80% wet basis), probably due to a higher biodegradation as it was the most aged sludge in the pit. According to the experimental results and calculations, the pumping requirements during pit emptying will decrease drastically by increasing the moisture content of the sludge. The addition of water into the pit would then facilitate the pit emptying operation by reducing the head and power required for pumping. However, this practice would require employing considerable amounts of water and handling higher volumes of sludge, which would lead to longer pit emptying times and increase the difficulty of the operation. For example, increasing the moisture content of the sludge from 75 to 90% will reduce the head and power of the pump by a factor 100, but will triplicate the amount of water in the sludge and, consequently, the time for pit emptying. Therefore, a compromise has to be made between increasing the pumping feasibility and adding water to the pit.

'LaDePa' process for the drying and pasteurization of faecal sludge from VIP latrines using infrared radiation.

This paper studies a faecal sludge treatment process, LaDePa (Latrine Dehydration and Pasteurization), which includes: (i) the characterization of the rheological and plastic behaviour of faecal sludge in the feeding section; (ii) the study of the drying and pasteurization performance of the process using a laboratory-scale prototype; and (iii) an evaluation of the processed faecal sludge for reuse in agriculture or as a biofuel. Experiments conducted using a rheometer show that the faecal sludge exhibits shear thinning behaviour, i.e. viscosity decrease with shear rate increase. Plasticity tests in a cone penetrometer showed that the faecal sludge has a more liquid than plastic behaviour, which may affect extrusion quality, unless a plasticizer is added, as sawdust in this study. The extent of drying and pasteurization of the samples was determined based on moisture content and the presence of viable Ascaris eggs respectively. As the intensity of infrared radiation was increased, drying was faster and more efficient in terms of energy consumption. However, the pellets were thermally degraded at temperatures above 200 °C. After processing in the LaDePa, Ascaris eggs were deactivated or severely damaged so that they would be not able to develop. The last part of the study was conducted by determining the content of nutrients (C, N, P, K) and calorific value. The results showed that the processed pellets have suitable characteristics for reuse in agriculture and as a biofuel: similar nutrient content to manure and compost, and similar calorific value to wood. Drying did not affect the nutrient content and calorific value of the dry bone of faecal sludge.

Spontaneous pneumothorax and alpha 1-antitrypsin deficiency.

Spontaneous pneumothorax has been observed in patients with abnormal levels of alpha 1-antitrypsin. We report the case of a young woman with a low level of alpha 1-antitrypsin who presented with recurrent episodes of spontaneous pneumothorax and who required pleuroscopy, apical lung resection, and pleurodesis.

Sarcoidosis after renal transplantation.

This is the case of a 41-year-old renal transplant recipient taking tacrolimus immunosuppressive therapy, who had a large pleural effusion, found on a chest radiograph during the work-up of digital clubbing. The patient had undergone a renal transplant 17 months earlier for end-stage renal disease secondary to immunoglobulin A nephropathy. Analysis of the effusion fluid demonstrated a lymphocytic exudate. Biopsy specimens of pleural and lung tissues showed noncaseating granulomas. Fluid and tissue cultures were negative for viral, fungal, and bacterial pathogens. Diagnosis of sarcoidosis was established by identification of noncaseating granulomas in pleural and lung tissue, the exclusion of other conditions, and rapid resolution of the effusion after the institution of corticosteroid therapy. The patient has remained free of pulmonary symptoms and had normal chest radiographs during the 20-month follow-up period.

Non-invasive mechanical ventilation: the benefits of the BiPAP system.

Many of the complications with endotracheal intubation and invasive mechanical ventilation can be avoided with the use of non-invasive mechanical ventilation (NIMV). This technique has been especially successful in treating patients with acute respiratory failure (ARF). NIMV improves gas exchange, avoids complications caused by endotracheal intubation, and allows patients to talk and take medications orally. This article reviews our experiences treating 27 patients with ARF with a BiPAP (bi-level positive airway pressure) ventilator. This is a portable unit which allows for selection of different modes of ventilation and adjustment of inspiratory and expiratory pressures. Non-invasive mechanical ventilation should be considered in patients presenting with ARF who are hemodynamically stable and in whom spontaneous breathing is preserved.

Postoperative respiratory insufficiency.

Respiratory insufficiency is one of the most common and most serious complications of the postoperative period. Preexisting risk factors include cardiopulmonary disease, significant smoking history, obesity and advanced age. The risk of postoperative respiratory insufficiency is increased in emergency surgical procedures (particularly those related to trauma), procedures involving the chest or upper abdomen and procedures requiring prolonged anesthesia. Postoperatively, prolonged sedation or neuromuscular blockade, cardiovascular instability, respiratory problems and immobilization are important risk factors. Common clinical causes of respiratory insufficiency are atelectasis, aspiration, pulmonary edema and pulmonary embolism. Management strategies are directed at treatment of the cause of the insufficiency and restoration of pulmonary function. All surgical patients should be carefully assessed before surgery, monitored closely during and after the procedure, and aggressively treated to prevent or correct respiratory insufficiency.

Intraocular pressure during mechanical ventilation with different levels of positive end-expiratory pressure.

OBJECTIVE: To determine the effect of positive end-expiratory pressure (PEEP) on intraocular pressure. DESIGN: Prospective, controlled, longitudinal, dual center study. In one group, patients served as their own control. In the second group, isolated determinations of intraocular pressure were made in mechanically ventilated patients receiving PEEP. SETTING: Adult intensive care units of two university hospitals. PATIENTS: Intraocular pressures were measured serially in eight patients during the recovery phase of different clinical conditions and in 22 patients receiving mechanical ventilation with PEEP > or = 10 cm H2O for > 24 hrs. INTERVENTIONS: Group A) In eight patients, a PEEP dose-response curve was established (PEEP 0, 5, 10, 15, and 0 cm H2O every 15 mins). Intraocular pressures were measured at the end of each period. Group B) In 22 patients, measurement of intraocular pressures were done while the patients received mechanical ventilation with PEEP > or = 10 cm H2O for at least > 24 hrs. MEASUREMENTS AND MAIN RESULTS: In both groups, there was a positive correlation between the PEEP level and the central venous pressure (p < .05 in group A, and p < .03 in group B). No relationships between intraocular pressure and PEEP or central venous pressure were observed. However, there was a correlation between intraocular pressure and length of PEEP therapy (p < .03). We found ocular hypertension in only one patient (right eye intraocular pressure = 26 mm Hg; left eye intraocular pressure = 24 mm Hg). CONCLUSIONS: Short-term therapy with PEEP of < or = 15 cm H2O does not present a clinically important significant risk for intraocular pressure increase in a population with normal basal ocular tonometry. During prolonged mechanical ventilation with PEEP, increments in intraocular pressure may occur, but these increments appear to not be of a clinically relevant magnitude.

Understanding circulatory shock. Is it hypovolemic, cardiogenic, or vasogenic?

Circulatory shock comprises a group of complex circulatory syndromes that result from a variety of conditions. It alters the function of most organ systems and has very high mortality. Identification of the type of shock (hypovolemic, cardiogenic, vasogenic, or a combination) and optimal treatment are aided by hemodynamic monitoring, including determination of preload, cardiac output, and systemic vascular resistance. Experimental studies and isolation of bioactive substances have improved understanding of the mechanisms involved in shock. Restoration of intravascular volume, cardiac contractility, and vascular tone and control of the underlying septic process when applicable are the basis of current therapy. Close monitoring and support of the affected organ systems in an intensive care environment facilitate recovery. Encouraging results with new treatments indicate improved chances for a satisfactory outcome in patients with circulatory shock.

Positive-pressure ventilation with positive end-expiratory pressure and atrial natriuretic peptide release.

The effect of positive-pressure ventilation (PPV) with PEEP on the release of alpha-atrial natriuretic peptide (ANP) was investigated in both humans and an experimental model. In the human study, systemic artery blood samples from 22 critically ill patients were analyzed for ANP. Seventeen of these patients received PPV with different levels of PEEP (5 to 15 cm H2O). The remaining five patients were breathing spontaneously (0 PEEP). There was no significant difference in plasma levels of ANP obtained at different levels of PEEP, and no correlation between ANP vs. wedge pressure or CVP was found. For the experimental group, in six dogs a PEEP dose-response curve was established (PEEP 0, 5, 10, 15, 0 cm H2O every 45 min). Blood samples from pulmonary and systemic arteries were obtained for ANP determination, and urine and Na excretion were measured at the end of each period. Neither significant interaction between PEEP and ANP was observed, nor did levels of this peptide correlate with the decrease in cardiac output (p less than .05) and urine output (p less than .05), or with the increase in CVP (p less than .05) observed during PEEP. ANP concentrations in the pulmonary and systemic arteries were similar. In 14 human samples, ANP was determined by radioimmunoassay and radioreceptor assay systems, but the level obtained by both methods did not significantly correlate.(ABSTRACT TRUNCATED AT 250 WORDS)

Beneficial effect of norepinephrine in the treatment of circulatory shock caused by tricyclic antidepressant overdose.

The beneficial effect of dopamine in circulatory shock induced by tricyclic antidepressants (TCA) overdose may be decreased due to compromise of the endogenous stores of norepinephrine caused by TCA. The successful outcome of two cases of TCA overdose complicated by hypotension, unresponsive to an initial treatment with physostigmine fluid challenge and dopamine (greater than 15 micrograms/kg/min) but subsequently responsive to an infusion of norepinephrine is reported.

Long-term survival after endobronchial fire during treatment of severe malignant airway obstruction with the Nd:YAG laser.

We present a case of Nd:YAG laser treatment of nearly total airway obstruction by malignant tumor in which an endobronchial fire occurred. The patient survived without complications of the fire and was followed-up until death over 22 months after the fire. The events leading to the fire are presented and recommendations provided to prevent similar occurrences.

Cardiac arrest after acute hyperphosphatemia.

Symptoms of hyperphosphatemia usually relate to the associated hypocalcemia. In a 33-year-old patient accidental infusion of a bolus of potassium phosphate (5 ml intravenously) was immediately followed by cardiac arrest. During CPR, clinically important hypocalcemia or hyperkalemia was not detected, but serum phosphorus was significantly increased. Because acute phosphate load can precipitate life-threatening cardiac arrhythmias, familiarity with doses and rate of infusion of phosphate is extremely important.

Beneficial effect of thyrotropin-releasing hormone in canine hemorrhagic shock.

The effects of thyrotropin-releasing hormone (TRH) on hemodynamic variables, oxygen delivery (DO2), and oxygen consumption (VO2) variables in canine hemorrhagic shock were studied. Anesthetized adult dogs were bled over 30 min to a mean arterial pressure (MAP) of 50 mm Hg. Shock was maintained at this level for half an hour. The animals were divided alternatively into two groups. In the first group (n = 5) a bolus of TRH (2 mg/kg) was given intravenously. The second group (n = 5) served as control and received equal amounts of D5W. Blood samples were obtained regularly up to 120 minutes after TRH or placebo. Differences in the two groups were statistically tested. After TRH, MAP pressure, cardiac output, and systemic vascular resistance increased significantly. DO2 improved after TRH but VO2 remained unchanged. In all dogs, sequential beta endorphin level were measured and were shown to rise after induction of shock. This data indicates that TRH may be of therapeutic benefit in the treatment of hemorrhagic shock and that beta endorphin may be an important pathophysiologic factor.