Hyperkalaemia and potassium binders: Retrospective observational analysis looking at the efficacy and cost effectiveness of calcium polystyrene sulfonate and sodium zirconium cyclosilicate.

WHAT IS KNOWN AND OBJECTIVE: Hyperkalaemia is a common medical emergency in patients admitted to hospital. There is a limited evidence base supporting some of the commonly applied treatment strategies. Although, NICE has recommended the use of sodium zirconium cyclosilicate (SZC) (TA599) and patiromer (TA623) in both acute and chronic hyperkalaemia, there is a limited evidence base for their use in acute hyperkalaemia in the hospital setting, particularly when compared to the present standard of care calcium polystyrene sulfonate (CPS). METHODS: A retrospective review of the electronic patient record system across our hospital over a 6-month period identified 138 patients who received either SZC (65 patients) or CPS (73 patients) to manage hyperkalaemia, investigating their efficacy and cost effectiveness. Results were analysed using simple descriptive statistics. Based on the results a naïve cost comparison between the two drugs was made. RESULTS AND DISCUSSION: CPS and SZC both effectively reduced plasm potassium concentrations in patients with hyperkalaemia (6.07 and 6.03 mmol/L respectively) by 1.17 mmol/L and 1.24 mmol/L taking a similar amount of time to work (2.97 days vs. 3 days). The principle causes of hyperkalaemia identified were acute kidney injury, medication, and chronic kidney disease. Cost comparison analysis which took into account raw product price and time needed to dispense medications revealed that CPS has slightly better cost effectiveness compared to SZC albeit at a cost of increased staff input. WHAT IS NEW AND CONCLUSION: Both CPS and SZC were equally effective at lowering acutely raised potassium concentrations. The cost difference between the two products appears to be small. Claims regarding the benefits of newer agents over older established medications need to be properly explored in randomized trials rather than being based on small scale non-comparative studies.

Study of the Q branch structure of the 14N and 15N isotopologues of the ν4 band of ammonia using frequency chirped quantum cascade lasers.

Intrapulse quantum cascade (QC) laser spectrometers are able to produce both saturation and molecular alignment of a gas sample owing to the rapid sweep of the radiation through the absorption features. In the QC lasers used to study the (14)N and (15)N isotopologues of the ν4 band of ammonia centered near 1625 cm(-1), the variation of the chirp rate during the scan is very large, from ca. 85 to ca. 15 MHz ns(-1). In the rapid chirp zone the collisional interaction time of the laser radiation with the gas molecules is short, and large rapid passage effects are seen, whereas at the slow chirp end the line shape resembles that of a Doppler broadened line. The total scan range of the QC laser of ca. 10 cm(-1) is sufficient to allow the spectra of both isotopologues to be recorded and the rapid and slow interactions with the laser radiation to be seen. The rapid passage effects are enhanced by the use of an off axis Herriott cell with an effective path length of 62 m, which allows a buildup of polarization to occur. The effective resolution of the chirped QC laser is ca. 0.012 cm(-1) full width at half-maximum in the 1625 cm(-1) region. The results of these experiments are compared with those of other studies of the ν4 band of ammonia carried out using Fourier transform and Laser Stark spectroscopy. They also demonstrate the versatility of the down chirped QC laser for investigating collisional effects in low pressure gases using long absorbing path lengths.

The ac Stark effect in nitric oxide induced by rapidly swept continuous wave quantum cascade lasers.

A large ac Stark effect has been observed when nitric oxide, at low pressure in a long optical path (100 m) Herriot cell, is subjected to infrared radiation from a rapidly swept, continuous wave infrared quantum cascade laser. As the frequency sweep rate of the laser is increased, an emission signal induced by rapid passage occurs after the laser frequency has passed through the resonance of 1-0 R(11.5)(3/2 /)molecular absorption line. At very high sweep rates a laser field-induced splitting of the absorptive part of the signal is observed, due to the ac Stark effect. This splitting is related to the Autler-Townes mixing of the e, f lambda doublet components of the 1-0 R(11.5)(3/2) transition, which lie under the Doppler broadened envelope.

Observation of infrared free-induction decay and optical nutation signals from nitrous oxide using a current modulated quantum cascade laser.

Free induction decay (FID), optical nutation, and rapid passage induced signals in nitrous oxide, under both optically thin and optically thick conditions, have been observed using a rapid current pulse modulation, or chirp, applied to the slow current ramp of a quantum cascade (QC) laser. The variation in optical depth was achieved by increasing the pressure of nitrous oxide in a long path length multipass absorption cell. This allows the variation of optical depth to be achieved over a range of low gas pressures. Since, even at the highest gas pressure used in the cell, the chirp rate of the QC laser is faster than the collisional reorientation time of the molecules, there is minimal collisional damping, allowing a large macroscopic polarization of the molecular dipoles to develop. This is referred to as rapid passage induced polarization. The resultant FID signals are enhanced due to the constructive interference between the field within the gas generated by the slow ramp of the laser (pump), and that of the fast chirp of the laser (probe) signal generated by pulse modulation of the continuously operating QC laser. The FID signals obtained at large optical depth have not been observed previously in the mid-infrared regions, and unusual oscillatory signals have been observed at the highest gas pressures used.

Sub-Doppler spectra of infrared hyperfine transitions of nitric oxide using a pulse modulated quantum cascade laser: rapid passage, free induction decay, and the ac Stark effect.

Using a low power, rapid (nsec) pulse-modulated quantum cascade (QC) laser, collective coherent effects in the 5 µm spectrum of nitric oxide have been demonstrated by the observation of sub-Doppler hyperfine splitting and also Autler-Townes splitting of Doppler broadened lines. For nitrous oxide, experiments and model calculations have demonstrated that two main effects occur with pulse-modulated (chirped) quantum cascade lasers: free induction decay signals, and signals induced by rapid passage during the laser chirp. In the open shell molecule, NO, in which both Λ-doubling splitting and hyperfine structure occur, laser field-induced coupling between the hyperfine levels of the two Λ-doublet components can induce a large ac Stark effect. This may be observed as sub-Doppler structure, field-induced splittings, or Autler-Townes splitting of a Doppler broadened line. These represent an extension of the types of behaviour observed in the closed shell molecule nitrous oxide, using the same apparatus, when probed with an 8 µm QC laser.

What influences prescribing decisions in a multimorbidity and polypharmacy context on the acute medical unit? An interprofessional, qualitative study.

RATIONALE, AIMS AND OBJECTIVES: The primary aim of the study was to understand the mindset of doctors and pharmacists, as they embark upon prescribing in a multimorbidity and polypharmacy context during routine practice at a hospital acute admissions unit. The study also aimed to evaluate to what extent attitudes, embedded within real-life decision-making scenarios, relate to existing theory and models of prescribing decisions. METHODS: Anonymized case studies were identified from the medical notes of patients aged 65 and over with conditions likely to be associated with multimorbidity, medication issues and polypharmacy: namely: fall, urinary tract infection, confusion or lower respiratory tract infection. A total of 39 doctors based on the acute medical admissions unit and 9 pharmacists were recruited to one of three focus groups. Patient case-studies provided the context for discussion from which verbatim transcripts were thematically analyzed using an interpretative, qualitative approach. Sub-themes were matched to Murshid and Mohaidin's proposed model of physician prescribing decisions. RESULTS: Seven principal themes were identified that were associated with prescribing decisions on the acute medical unit, namely, "patient characteristics," "drug characteristics," "pharmacist factors," "trustworthiness," "reliability of medication history," "competing priorities" and "responsibilities of prescribers." CONCLUSION: Prescribing decisions on the acute medical admissions unit were influenced by a variety of factors, some of which have already been acknowledged within existing theories and models. The findings provisionally offer new insights, which, subject to confirmation by further research, bring to light three attitudinal characteristics that may impact negatively upon the quality of prescribing decisions. These include, first, how perceived poor reliability of medication history may result in information gaps that compromise prescribing decisions; second, how competing priorities restrict doctors' aptitude to conduct a review of medication and finally, how doctors may rationalize the assignment of medication review to the GP.

An investigation of collisional processes in a Dicke narrowed transition of water vapor in the 7.8 microm spectral region by frequency down-chirped quantum cascade laser spectroscopy.

Information about intermolecular potentials is usually obtained through the analysis of the absorption line shapes recorded in the frequency domain. This approach is also adopted to study the effects of motional narrowing and speed dependence of the pressure broadening coefficients. On the other hand, time domain measurements are directly related to molecular collisions and are therefore frequently employed to study molecular relaxation rates, as well as the effects of velocity changing collisions and the speed dependence of the absorption cross sections. Intrapulse quantum cascade laser spectrometers are able to produce both saturation and molecular alignment of the gas sample. This is due to the rapid sweep of the radiation through the absorption features. In the present work the frequency down-chirped radiation emitted by an intrapulsed quantum cascade laser operating near 7.8 mum is employed to investigate the collisional relaxation processes, and the collisional narrowing, in the 15(0,15)<--16(1,16) and 15(1,15)<--16(0,16) doublet in the water vapor nu(2) band. The effects of He, Ne, Ar, N(2), and CO(2) as collisional partners are investigated. The experimental results clearly indicate the dependence of the collisional cross sections upon the chirp rate. They also demonstrate that by using different chirp rates it is possible to gain information about the intermolecular processes driving the molecular collisions and the related energy transfer.

Time dependent measurements of nitrous oxide and carbon dioxide collisional relaxation processes by a frequency down-chirped quantum cascade laser: rapid passage signals and the time dependence of collisional processes.

Intrapulse quantum cascade laser spectrometers are able to produce both saturation and molecular alignment of the gas sample. This is due to the rapid sweep of the radiation through the absorption features. The intrapulse time domain spectra closely resemble those recorded in coherent optical nutation experiments. In the present paper, the frequency down-chirped technique is employed to investigate the nitrous oxide-foreign gas collisions. We have demonstrated that the measurements may be characterized by the induced polarization dominated and collision dominated measurement limits. The first of these is directly related to the time dependence of the long range collision cross sections. Among the collisional partners considered, carbon dioxide shows a very unusual behavior of rapid polarization damping, resulting in the production of symmetrical line shapes at very low gas buffer pressures. In the collision dominated regime, the pressure broadening parameters, which we have derived, are comparable at slow chirp rates, with those derived from other experimental methods. By comparing the pressure broadening coefficients of Ar, N(2), and CO(2) with those of He, making use of the chirp rate independence of the pressure broadening by helium, we have shown that at higher chirp rates there is clear evidence of the chirp-rate dependence of the pressure broadening parameters of N(2) and CO(2).

Nitrous oxide-induced toxic leukoencephalopathy.

Toxic leukoencephalopathy (TL) is characterised by an insult to the myelin of the cerebral white manner which can be attributed to a number of offending agents, including drugs of abuse. We report a case of a fit and well young man presenting to hospital with an altered mental state. It was subsequently determined that the patient inhaled a significant volume of nitrous oxide recreationally. Nitrous oxide is easily accessible and the second most consumed drug among young adolescents (16-24 years old). Following extensive investigations and brain imaging, the patient was subsequently diagnosed with TL. After a prolonged hospital admission, he went on to make a complete neurological recovery.

The relationship between antemortem and postmortem morphine concentrations.

Context of the Article: An important forensic problem is whether the presence of a drug such as morphine caused or contributed to a death or was merely incidental. The reliance that can be based on postmortem drug concentrations remains controversial. To investigate this further we obtained antemortem and postmortem samples of individuals admitted to hospital who were receiving morphine and who died in hospital.Methods: Eleven subjects were recruited. Samples were sent for analysis for free and total morphine concentrations.Results: The median difference (postmortem - antemortem) free morphine concentration was 25.5 (range 0 to +126) µg/L, p < .01; the mean difference between postmortem and antemortem total morphine concentration was 34.5 (range -225 to 342) µg/L (not significant).Discussion: Our study supports previous investigators who note that there is an inconstant and sometimes tenuous relationship between ante- and postmortem morphine concentrations.

Femtosecond synchronously mode-locked vertical-external cavity surface-emitting laser.

The behavior of a room temperature synchronously mode-locked vertical-external cavity surface-emitting laser (VECSEL) operating at 980 nm is reported. The laser performance was found to be qualitatively the same for different pump pulse duration (3.6 ps and 70 fs). The pulse duration of the laser is limited by strong self-phase modulation to around 10-40 ps. By compressing the strongly chirped pulses generated directly from the laser, ultrashort pulses with duration of around 200 fs with maximum peak powers of 1.3 kW at 80 MHz were obtained. Multiple pulsing of the laser was observed and the effects of cavity length detuning on pulse width and spectral bandwidth have been investigated.

Carbon dioxide poisoning.

Carbon dioxide is a physiologically important gas, produced by the body as a result of cellular metabolism. It is widely used in the food industry in the carbonation of beverages, in fire extinguishers as an 'inerting' agent and in the chemical industry. Its main mode of action is as an asphyxiant, although it also exerts toxic effects at cellular level. At low concentrations, gaseous carbon dioxide appears to have little toxicological effect. At higher concentrations it leads to an increased respiratory rate, tachycardia, cardiac arrhythmias and impaired consciousness. Concentrations >10% may cause convulsions, coma and death. Solid carbon dioxide may cause burns following direct contact. If it is warmed rapidly, large amounts of carbon dioxide are generated, which can be dangerous, particularly within confined areas. The management of carbon dioxide poisoning requires the immediate removal of the casualty from the toxic environment, the administration of oxygen and appropriate supportive care. In severe cases, assisted ventilation may be required. Dry ice burns are treated similarly to other cryogenic burns, requiring thawing of the tissue and suitable analgesia. Healing may be delayed and surgical intervention may be required in severe cases.

The use of levomepromazine in Hyperemesis Gravidarum resistant to drug therapy--a case series.

Hyperemesis Gravidarum (HG) is a potentially serious complication of early pregnancy, which may rarely be severe enough to warrant termination of pregnancy. HG requires prompt treatment with intravenous fluids, thiamine supplementation and appropriate anti-emetic therapy. Anti-histamines such as promethazine are favoured as first-line agents, with prochlorperazine being used as a second-line drug. However, there is no clear data as to the most appropriate drug if these are ineffective. A case series of six women who presented with HG resistant to drug treatment is described. In these cases, levomepromazine 6.25mg tds was used to control HG. Five pregnancies progressed leading to live born infants with no evidence of congenital anomaly. One pregnancy resulted in an intra-uterine death with no external or ultrasound evidence of congenital anomaly. The role of phenothiazines in the pharmacological management of HG is discussed.

Anti-oxidative properties of beta-blockers and angiotensin-converting enzyme inhibitors in congestive heart failure.

BACKGROUND: Chronic elevation of plasma catecholamines and sympathetic stimulation in chronic heart failure (CHF) leads to increased production of free radicals, and so possibly to endothelial damage/dysfunction and atheroma formation. Abnormal oxidative stress may therefore be related to some of the high mortality and morbidity in CHF. The objective of the present prospective open study was to compare the effects of beta-blockers and ACE inhibitors in relation to oxidative stress and endothelial damage in CHF. METHODS: We studied 66 outpatients with CHF: 46 patients were established on an ACE inhibitor and were then started on a beta-blocker, and 20 patients not previously on ACE-inhibitors were started on lisinopril. Baseline levels of the measured parameters were compared to 22 healthy control subjects. Serum lipid hydroperoxides (LHP) and total antioxidant capacity (TAC) were determined as indices of oxidative damage and antioxidant defence, and plasma von Willebrand factor (vWf) as an index of endothelial damage/dysfunction. RESULTS: Baseline indices for the measures of oxidative damage and endothelial function in the 66 CHF patients were significantly higher than healthy control subjects [median LHP 7.5 (5.9-12.6) vs. 4.8 micromol/l, P=0.0022; TAC 428 (365-567) vs. 336 Trollox Eq. Units, P=0.0005; mean vWf 134+/-27 vs. 89+/-23 IU/dl, P<0.0001]. Following 3 months of maintenance therapy with beta-blockers, there was significant reduction in LHP levels, but not TAC or vWf. ACE inhibitor therapy also significantly reduced vWf levels, but failed to have any statistically significant effects on LHP or TAC. CONCLUSION: This pilot study suggests that oxidative stress in CHF may be due to increased free radical production or inefficient free radical clearance by scavengers. beta-Blockers, but not ACE inhibitors, reduced lipid peroxidation in patients with CHF. No relation was demonstrated between a reduction in oxidative damage and endothelial damage/dysfunction.

Delivering outpatient antibiotic therapy (OPAT) in an Acute Medical Unit.

Outpatient antibiotic therapy (OPAT) is being developed and practised in an increasing number of acute hospitals within the United Kingdom. This article is a review of the OPAT service delivered by a large inner city hospital over the last two years. The service demonstrates the key elements of OPAT demonstrating different delivery models, aspects of patient selection, spectrum of infections treated, choice and delivery of antimicrobials, efficacy, patient safety, outcomes, and the cost-effectiveness of this programme.

Recurrent Kikuchi-Fujimoto disease.

We report the case of a 27-year-old, UK-born, Asian woman who suffered a rare recurrence of Kikuchi-Fujimoto disease. She presented with tender lymphadenopathy of the neck, fever and a prodrome of flu-like symptoms. She had a past medical history of biopsy-proven Kikuchi-Fujimoto disease of her right axilla 2 years earlier, which required no treatment. Following her repeat admission, a cervical lymph node biopsy confirmed a diagnosis of recurrent Kikuchi-Fujimoto disease. She did not improve despite treatment with paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs). She was started on high-dose prednisolone and her symptoms, pyrexia, and inflammatory markers settled within 24 h. She continually improved and the prednisolone was slowly reduced over 9 months. Kikuchi-Fujimoto is a rare, benign, self-limiting disease that presents with lymphadenopathy and fever. It rarely reoccurs. The severity, recurrence and the different body site make this an unusual case.

Bupropion toxicokinetic: a case report.

CONTEXT: The toxicokinetics of sustained-release bupropion are not well described. CASE: A 23-year-old Caucasian male took an overdose of 5,700 mg of sustained release bupropion with no co-ingestant. Venous serum samples were assayed for bupropion concentrations over the next 5 days. The peak concentration was 1.114 mg/L. The observed T(max) was found to be 8.25 h, the calculated alpha half-life 10.9 h (+/-SE of 4.47%), and the calculated beta half-life 19.8 h (+/-SE 12.62%). The alpha half-life and T(max) differ significantly from those seen in therapeutic doses. DISCUSSION: Bezoar formation may underlie these differences. Interventions which reduce the absorption of sustained release bupropion may be effective in overdose.

Out-patient detection of deep vein thrombosis using a combination of risk scoring and strain-gauge-plethysmography: a follow-up study.

Patients are frequently referred to hospital for exclusion of deep vein thrombosis (DVT); however, the diagnosis is only confirmed in 12% of those undergoing investigation. An effective strategy is required, which minimises the number of negative investigations, while safely excluding or confirming the diagnosis. This study investigates the combination of clinical risk scoring and strain-gauge plethysmography in the initial assessment of patients with suspected DVT. A survey was conducted of 1300 patients referred with suspected DVT over the course of a year. The results of this investigation were comparable to previous clinical trials and supports the use of strain-gauge plethysmography combined with clinical risk score in a busy acute medical unit.