The whole-cell patch-clamp recording technique was used to measure volume-activated currents in K+-free solutions in RINm5F and HIT-T15 insulinoma cells and in dispersed rat islet cells. Cell swelling, induced by intracellular hypertonicity or extracellular hypotonicity, caused activation of an outwardly rectifying conductance which could be subsequently inactivated by hypertonic extracellular solutions. The conductance required adenosine 5'-triphosphate (ATP) in the pipette solution but was Ca2+ independent. Na+ and Cl- substitution studies suggested that the swelling-activated current is Cl- selective with a halide permeability sequence of Br > Cl > I. The conductance was reversibly inhibited by the anion channel inhibitors 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) and by 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB). Further evidence for a volume-activated anion conductance was provided by studies of volume regulation in insulin-secreting cells. When RINm5F cells were exposed to a hypotonic medium, the initial cell swelling was followed by a regulatory volume decrease (RVD). This RVD response was also inhibited by DIDS and by NPPB. These data therefore provide evidence for a volume-activated anion conductance in insulin-secreting cells which could be involved in the RVD following osmotic stress. A possible role for the conductance in hypotonically induced insulin release is also discussed.

ObjectiveTo determine the prevalence, nature and predictors of prescribing errors (PEs) in three mental health hospitals.SettingInpatient units in three National Health Service (NHS) mental health hospitals in the North West of England.ParticipantsTrained clinical pharmacists prospectively recorded the number of PEs in newly written or omitted prescription items screened during their routine work on 10 data collection days. A multidisciplinary panel reviewed PE data using established methods to confirm (1) the presence of a PE, (2) the type of PE and (3) whether errors were clinically relevant and likely to cause harm.Primary outcome measuresFrequency, nature and predictors of PEs.ResultsOf 4427 screened prescription items, 281 were found to have one or more PEs (error rate 6.3% (95% CI 5.6 to 7.1%)). Multivariate analysis revealed that specialty trainees (OR 1.23 (1.01 to 1.51)) and staff grade psychiatrists (OR 1.50 (1.05 to 2.13)) were more likely to make PEs when compared to foundation year (FY) one doctors, and that specialty trainees and consultant psychiatrists were twice as likely to make clinically relevant PEs (OR 2.61 (2.11 to 3.22) and 2.03 (1.66 to 2.50), respectively) compared to FY one staff. Prescription items screened during the prescription chart rewrite (OR 0.52 (0.33 to 0.82)) or at discharge (OR 0.87 (0.79 to 0.97)) were less likely to be associated with PEs than items assessed during inpatient stay, although they were more likely to be associated with clinically relevant PEs (OR 2.27 (1.72 to 2.99) and 4.23 (3.68 to 4.87), respectively). Prescription items screened at hospital admission were five times more likely (OR 5.39 (2.72 to 10.69)) to be associated with clinically relevant errors than those screened during patient stay.ConclusionsPEs may be more common in mental health hospitals than previously reported and important targets to minimise these errors have been identified.

ObjectiveMedication administration errors (MAEs) are a common risk to patient safety in mental health hospitals, but an absence of in-depth studies to understand the underlying causes of these errors limits the development of effective remedial interventions. This study aimed to investigate the causes of MAEs affecting inpatients in a mental health National Health Service (NHS) hospital in the North West of England.MethodsRegistered and student mental health nurses working in inpatient psychiatric units were identified using a combination of direct advertisement and incident reports and invited to participate in semi-structured interviews utilising the critical incident technique. Interviews were designed to capture the participants’ experiences of inpatient MAEs. All interviews were transcribed verbatim and subject to framework analysis to illuminate the underlying active failures, error/violation-provoking conditions and latent failures according to Reason’s model of accident causation.ResultsA total of 20 participants described 26 MAEs (including 5 near misses) during the interviews. The majority of MAEs were skill-based slips and lapses (n = 16) or mistakes (n = 5), and were caused by a variety of interconnecting error/violation-provoking conditions relating to the patient, medicines used, medicines administration task, health care team, individual nurse and working environment. Some of these local conditions had origins in wider organisational latent failures. Recurrent and influential themes included inadequate staffing levels, unbalanced staff skill mix, interruptions/distractions, concerns with how the medicines administration task was approached and problems with communication.ConclusionsTo our knowledge this is the first published in-depth qualitative study to investigate the underlying causes of specific MAEs in a mental health hospital. Our findings revealed that MAEs may arise due to multiple interacting error and violation provoking conditions and latent ‘system’ failures, which emphasises the complexity of this everyday task facing practitioners in clinical practice. Future research should focus on developing and testing interventions which address key local and wider organisational ‘systems’ failures to reduce error.

A retrospective cohort study, with a mirror-image design, was used to measure inpatient service utilization in 63 consecutive patients started on clozapine from a geographical catchment area compared to a control group matched for previous inpatient service use. An intent-to-treat analysis, including those patients (n = 28) who discontinued clozapine during the study period, showed a significant reduction in number of admissions and total time spent in hospital in the 2 years following clozapine initiation compared to the previous 2 years and to the follow-up period in the control group. This translated into a reduction of 7,300 pounds in hospitalization costs per patient started on clozapine, over the 2-year period. In those patients who continued clozapine treatment for the whole of the 2-year period, there was a two-thirds reduction in number of admissions and total time spent in hospital compared to no change in the clozapine discontinuers. These findings suggest that clozapine is a clinically and cost-effective intervention for severe schizophrenia in routine clinical settings.