Biomedical subjects
N Soni
Publications and source records attributed to N Soni.
C-reactive protein as an indicator of resolution of sepsis in the intensive care unit.
OBJECTIVE: To investigate the value of decreasing plasma C-reactive protein (CRP) concentrations as an indicator or resolution of microbiologically-proven sepsis. DESIGN: Retrospective analysis of CRP concentrations measured during episodes of microbiologically-proven sepsis. A receiver-operating characteristic (ROC) curve was used to assess the usefulness of CRP as a test for resolution of sepsis. SETTING: The intensive care unit (ICU) of a teaching hospital. PATIENTS AND PARTICIPANTS: 32 episodes of microbiologically-proven sepsis occurring in 18 patients were followed from diagnosis until resolution. MEASUREMENTS AND RESULTS: Daily routine observations and blood testing were performed prospectively. The daily presence or absence of systemic inflammatory response syndrome (SIRS) was prospectively determined according to standard definitions. Concentrations of CRP were analysed retrospectively once the patients had left the ICU. A decrease in CRP by 25% or more from the previous day's level was a good indicator of resolution of sepsis, with a sensitivity of 97%, specificity of 95% and predictive value of 97%. In 13 cases (46%), a decrease in CRP preceded clinical resolution of sepsis; this was more likely to occur in patients with less severe sepsis than in those with severe sepsis or septic shock. CONCLUSION: Daily measurement of CRP is useful for monitoring the course of microbiologically-proven sepsis in ICU patients, and may be used to indicate successful treatment.
Oxygen uptake during rebreathing in a Mapleson A system.
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In vitro effects of HA-1A (Centoxin) on cytokine production in whole blood from intensive care unit patients.
The cytokines interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF alpha) have been implicated in the pathophysiology of sepsis and the systemic inflammatory response syndrome (SIRS). The anti-endotoxin antibody, HA-1A (Centoxin), introduced as a treatment for sepsis, was withdrawn because of possible toxicity in some patients. There has been little investigation of the effects of HA-1A on cytokine production. Sixty-one whole blood samples from 15 intensive care unit (ICU) patients with SIRS were incubated for 24 h with HA-1A and concentrations of cytokines determined. Concentrations of IL-6 exceeded those in samples incubated without HA-1A by more than 25% in five patients, of whom four died. One death occurred among 10 patients for whom IL-6 concentrations did not increase (P = 0.03). Incubation with HA-1A did not increase concentrations of IL-1 beta or TNF alpha. HA-1A did not affect cytokine production in whole blood from healthy subjects. HA-1A may induce IL-6 production in whole blood from some ICU patients and this response is associated with increased mortality. Immune therapies for treatment of sepsis and SIRS require careful evaluation of their ability to affect cytokine production, before they are introduced for general use.
Physiological scoring systems and audit.
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Endotoxin antibody for sepsis in infants.
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A high flow semi-open system for preoxygenation: an evaluation.
We have compared an alternative breathing system for preoxygenation comprising a Hudson face mask with high oxygen inflow (48 litre min-1) and a Mapleson A breathing system (100 ml kg-1 min-1). The study consisted of two parts: the first involved adult volunteers (10 male, seven female) and the second part used a lung model for spontaneous ventilation with a sinusoidal ventilatory wave pattern. In the volunteers, preoxygenation was achieved at mean times of 138 (SD 31.3) s and 164 (SD 36.7) s with the high flow semi-open and Mapleson A systems, respectively. In the lung model, at peak inspiratory flow rates of 30 and 40 litre min-1, the preoxygenation times were 139 and 120 s, respectively, with the semi-open system and 167 and 156 s with the Mapleson A system. The high flow semi-open system may be an alternative for current techniques, provided peak inspiratory flows are not excessive.
Nitrous oxide administration using commonly available oxygen therapy devices.
Administration of nitrous oxide is useful for providing sedation and analgesia. The therapeutic range for nitrous oxide is 20-30%. Several oxygen treatment devices have been used for administering nitrous oxide, but little is known about the concentrations of nitrous oxide and oxygen delivered to the trachea. We have studied this, using an analogue lung model, with several oxygen therapy devices. With a 1:1 nitrous oxide-oxygen mixture in the primary flow for all systems, end-expired nitrous oxide concentrations varied between 6.5% and 34.3%. Therapeutic concentrations were produced using the Hudson (nominal oxygen concentration 60%) fixed-performance mask, the variable performance Hudson mask at 4 litre min-1, the MC masks at 4 and 6 litre min-1 and the nasal prongs at 6 and 8 litre min-1. Simultaneous end-expired oxygen concentrations for all devices tested were within a safe range.
Colloid solutions in the critically ill. A randomised comparison of albumin and polygeline. 1. Outcome and duration of stay in the intensive care unit.
All patients admitted to an Intensive Care Unit were randomised to receive all volume replacement fluid as either human albumin solution or a synthetic colloid. A total of 475 patients were admitted during the study period. Patients' age, sex, APACHE score and calculated risk of death were assessed on admission. Outcome was assessed as length of Intensive Care stay and mortality. There was no difference between the groups. Subgroups of patients with APACHE score greater than 10, calculated risk of death greater than 50% and length of stay greater than 5 days were also evaluated but not significant differences were found between treatment groups. The use of albumin rather than 3.5% polygeline for volume replacement in the Intensive Care Unit has no influence on outcome.
Colloid solutions in the critically ill. A randomised comparison of albumin and polygeline 2. Serum albumin concentration and incidences of pulmonary oedema and acute renal failure.
All patients admitted to an Intensive Care Unit were assigned randomly to one of two groups, A and B. Group A received colloid volume replacement as 4.5% albumin whilst group B received a synthetic colloid, polygeline. This study describes the changes in serum albumin concentration in survivors and nonsurvivors in the two groups during their stay in the Intensive Care Unit. The incidences of renal failure and pulmonary oedema were also assessed. Serum albumin concentration decreased in all nonsurvivors. In survivors the serum albumin concentration decreased to a greater extent in the synthetic colloid group than in the albumin group. Despite the differences in serum albumin concentration there were no significant differences between the groups in the incidences of pulmonary oedema or renal failure.
An evaluation of oxygen delivery using nasal prongs.
Oxygen delivery using nasal prongs was assessed using a lung model for spontaneous ventilation. The analogue lung was attached to a manikin, which provided a model of the 'face and pharynx' to which the nasal prongs were applied. Oxygen concentrations were measured in the model trachea at varying fresh gas inflow and peak inspiratory flows. The study demonstrated enormous variability in the both the peak-inspired (26.3-90.0%) and end-expired concentrations (25.2-78.6%) of oxygen delivered to the trachea. There was a regular relationship between the ratio of peak inspiratory flows, expressed over fresh gas inflow and the end-expired oxygen concentrations which could allow estimation of inspired oxygen concentration.
Pre-oxygenation: the Hudson mask as an alternative technique.
The use of a simple oxygen facemask (Hudson) with high oxygen inflow (48 l.min-1) was investigated as a technique for pre-oxygenation, comparing it with the Magill system (oxygen flow: 100 ml.kg-1.min-1). One hundred and thirty-eight patients scheduled for elective gynaecological and orthopaedic surgery were studied: group 1, Hudson mask and group 2, Magill system (ASA 1-2, n = 107); group 3, Hudson mask and group 4, Magill system (ASA 3, n = 30). Pre-oxygenation was assessed by measuring the times to 97%, 95% and 93% arterial desaturation (finger pulse oximetry) following 3 min of pre-oxygenation. The times taken to achieve these end-points in all the study groups suggest that the Hudson mask offers an alternative technique for pre-oxygenation.
Rebreathing and the Humphrey ADE breathing system.
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Nitrous oxide-oxygen analgesia: the performance of the MC mask delivery system.
Nitrous oxide administration via an oxygen facemask such as the Mary Catterall (MC) is an accepted technique for supplementing regional anaesthesia. This study assessed the range of nitrous oxide and oxygen concentrations delivered to the trachea using a mechanical lung model. The inspired concentrations of these two gases were determined by the total fresh gas inflow rates, their concentrations in the fresh gas mixture and the peak inspiratory flow rate of the analogue lung. A 1:1 nitrous oxide-oxygen mixture in the fresh gas with an inflow rate of 4-6 l/min is recommended to ensure adequate oxygen delivery into the trachea as well as achieving the therapeutic concentrations of nitrous oxide (20-30%).
Septic atrial thrombus. A complication of central venous catheterisation.
A 77-year-old man underwent repair of a vesicocolic fistula following which he had a protracted stay in the intensive care unit due to recurrent septicaemia, which was initially caused by bowel anastomosis breakdown. Management included central venous cannulation and pulmonary artery catheter monitoring. A septic, mobile right atrial thrombus developed, which was successfully treated. The literature on this condition is reviewed.
C-reactive protein as a diagnostic test of sepsis in the critically ill.
Changes in the plasma concentration of C-reactive protein were assessed as a diagnostic test for sepsis in critically ill patients. Forty-nine episodes of secondary sepsis were identified in 31 patients. In 43 out of the 49 episodes there was a 25% or greater change in the concentration of C-reactive protein on the day that sepsis was diagnosed but in six episodes of sepsis the change was less than 25%. A 25% rise in the plasma concentration of C-reactive protein in the absence of other non-infective causes of a raised C-reactive protein, such as inflammation, tissue injury or surgery, is highly suggestive of infection, but failure of the C-reactive protein to rise does not eliminate a diagnosis of sepsis.
Plasma neopterin as an adjunct to C-reactive protein in assessment of infection.
C-reactive protein (CRP) concentrations are increased in plasma in people with inflammatory conditions and bacterial infections. Plasma neopterin concentrations are increased in people with bacterial septicemias, viral infections, and graft vs host disease. Plasma concentrations of CRP and neopterin were measured daily in 21 bone-marrow transplant (BMT) patients, 64 patients in intensive-care units (ICU), and 12 patients with squamous cell carcinoma of the head and neck (HN). In the BMT patients, plasma neopterin measurements in addition to CRP measurements allowed infectious episodes to be distinguished from graft vs host disease. In the ICU patients, increased concentrations of CRP were not specific for infection and the additional plasma neopterin measurements did not improve this specificity. In all three patient groups, the derivation of a neopterin/CRP ratio was of no clinical use. These three groups of patients showed patterns of CRP and neopterin concentrations characteristic of their underlying diseases, the BMT patients with the immunological activation of graft vs host disease showed predominantly increased concentrations of plasma neopterin, ICU patients with infectious and inflammatory conditions had increased concentrations of both CRP and neopterin in plasma, and the HN group with localized inflammation showed increased plasma concentrations of CRP without increases in neopterin.
The Bain, ADE, and Enclosed Magill breathing systems. A comparative study during controlled ventilation.
The Enclosed Magill, Humphrey ADE and the Bain breathing systems are all used for controlled ventilation of the lungs. This study compares the three systems in vitro with a lung model and in clinical practice. No difference was observed, with ventilatory variables commonly used in clinical practice, between the Bain and the ADE, while significantly lower end-tidal carbon dioxide values were observed with the Enclosed Magill (about 7%). Lower fresh gas flows can be used under these circumstances to maintain normocapnia with the Enclosed Magill than either the Bain or the Humphrey ADE.