Upper Limit Ventricular Stimulation in Respiratory Rate Responsive Pacing due to Electrocautery

Transient programmed upper limit stimulation (150 bpm) was observed during repetitively utilized electrocautery in the beginning of an open-heart surgical procedure in a patient with a minute ventilation rate responsive ventricular pacemaker. This tachycardia caused severe hemodynamic deterioration, and was also initiated by internal heart massage and manual ventilation. Considering the recommendations of the manufacturer, this series of serious events could have been prevented, when reprogramming to the inhibited mode had been executed in anticipation of the operation.     

Brain tumors and occupational exposures in a cohort of female textile workers in Shanghai, China

OBJECTIVES： This study assessed the associations between brain tumors and specific processes and exposures among female textile workers in Shanghai, China. METHODS： A case-cohort study was conducted that was nested in a cohort of textile workers originally included in a randomized trial of breast self-examination. Incident brain tumor cases （N=114） were identified from 1989 to 1998 from a tumor and death registry operated by the Shanghai Textile Industry Bureau. A subcohort （N=3188）, representing an agestratified random sample of the entire cohort, was selected as a comparison group.     

A review of the Transitional Emergency Nurse Practitioner

Introduction

A retrospective exploratory study was conducted to (i) explore the practice patterns of a Transitional Emergency Nurse Practitioner (TENP) working across two urban Emergency Departments (ED); (ii) identify the demographic characteristics of the TENP patient cohort; and (iii) identify if TENP patients were appropriately and timely managed.

Method

The study was conducted across two hospital sites over two consecutive years for a 3-month period. Data collection occurred during the months of December through to February. TENP patients were identified by hospital electronic medical record and were then grouped into a model that included ‘Fast Track’ or ‘See and Treat’ cohort. The cohorts were then analysed for diagnostic groups, age, sex, length of stay, triage category, and re-presentations.

Results

The TENP worked a total of 600 h (Site 1 252 h; Site 2 348 h) across the study period. The TENP managed a total of 481 patients (262 Site 1; 220 Site 2) during the study period. The majority of patients (412; 84%) were managed in the ‘See and Treat’ cohort (Site 1 246, 94%; Site 2 166, 75%) and 70 patients (16%) were managed in the ‘Fast Track’ cohort (Site 1 16, 4%; Site 2 54, 25%). The median length of stay for TENP managed patients was 143 min, with 96% of patients leaving the ED in less than 8 h. There were no TENP unplanned re-presentations at either site. The TENP managed more male patients across both sites. The majority (75%) of patients the TENP managed had musculoskeletal and/or wound conditions or injuries.

Conclusion

TENP practice across the two Sydney metropolitan ED sites was similar. The model adapted for Tertiary Referral centres was appropriate for smaller urban EDs. The study supports existing evidence of timely and appropriate care being delivered by TENPs across Australian EDs. Given the work practice similarities, the study demonstrates that State and/or National standards and policies could be developed for emergency advanced practice roles.     

Structural abnormalities of ventrolateral and orbitofrontal cortex in patients with familial bipolar disorder

Objectives: Abnormalities of ventral prefrontal function have been widely reported in bipolar disorder, but reports of structural abnormalities in the same region are less consistent. We examined the presence and location of ventral prefrontal abnormalities in a large sample of individuals with bipolar disorder and their relationship to gender, psychotic symptoms, and age. Methods: Structural magnetic resonance imaging brain scans were carried out on 66 individuals with bipolar disorder, type I, and 66 controls. Voxel‐based morphometry was used to examine differences in grey and white matter density between the groups and their relationship with a lifetime occurrence of psychotic symptoms and age. Results: Reductions in grey matter density were seen in the left and right lateral orbital gyri and the right inferior frontal gyrus, while white matter density reductions were seen in the corona radiata and the left temporal stem. In contrast, hallucinations and positive symptoms were associated with grey matter reduction in the left middle temporal gyrus. Age was more strongly associated with the right inferior frontal gyrus grey matter reductions in the bipolar group than in the controls, but not with any other finding. Conclusion: Abnormalities of the ventral prefrontal cortex are likely to be involved in the aetiopathology of bipolar disorder, while hallucinations appear to be more closely associated with temporal lobe abnormality, extending earlier work in schizophrenia. Further prospective studies are required to comprehensively address the trajectory of these findings.     

Donor cell leukemia developing six years after marrow grafting for acute leukemia

A patient who developed recurrent leukemia more than six years after marrow grafting from an HLA-identical same-sex sibling is reported. Difference in DNA restriction fragment length polymorphisms between donor and host demonstrated that the DNA in the recurrent leukemia sample was probably of donor origin. Possible mechanisms that could explain the long latent period between transplantation and expression of leukemic transformation are discussed. We conclude that future cases of late leukemic recurrence after marrow grafting should be studied to determine whether, in contrast to early relapses, late relapses occur in donor cells in most or all instances.     

The mechanism of white cell reduction by synthetic fiber cell filters

The mechanism of white cell (WBC) retention by synthetic fiber-based WBC filters was studied. Filters were made of nonwoven fleece prepared from polyester, surface-modified polyester, or polypropylene fibers. Human platelet concentrates were filtered through experimental filters consisting of 8 to 54 layers of nonwoven fleece with mean pore sizes from 7.3 to 14.2 microns. Filters made of fleece of smaller pore size removed WBCs less effectively than filters with larger-pore fleece. Retention of lymphocytes and granulocytes gradually dropped to 0 percent as increasing loads were applied to the filters. The maximal retention capacity for these cell types (i.e., the number of cells retained when "saturating" numbers of WBCs were applied) was proportional to the number of layers of filter material used. Platelet retention did not correlate with WBC retention. Depth filtration, rather than mechanical sieving, seems to be the principal means of WBC removal by nonwoven fiber filters. A low initial number of WBCs in the component to be filtered is important for successful WBC filtration.     

An inhibitory effect of veratridine during tetanic stimulation of the rat diaphragm

The membrane ‘labilizer’ veratridine (3.7 ± 10^-6 m) which potentiates the contractions at twitch (0.1 Hz) stimulation due to multiple discharges, inhibited the tetanic contractions (50 Hz in 10 s) and the simultaneously recorded electromyogram in a use-dependent way, leading to fading of tetanic tension. The effect was equal during indirect and direct stimulation, and could therefore be localized to the excitable sarcolemma. This was confirmed by intracellular recording of action potentials, showing a marked veratridine-induced fallout of action potentials during continuous 50 Hz stimulation, whereas endplate potentials were unaffected. Accordingly, veratridine probably caused a use-dependent inhibition of the Na⁺ channels of the excitable sarcolemma. The tetanic fade was unaffected by K⁺ depolarization, increased by hyperpolarization in K⁺-free solution, and decreased by high Ca²⁺. All these changes of the ionic concentrations inhibited the twitch potentiating effect of veratridine. Since hyperpolarization and increasing the electric field in the membrane with high Ca^,+ had opposite effects on the tetanic fade, the field change was probably not the cause of the antagonism in high Ca²⁺. Instead, a membrane stabilizing effect of high Ca²⁺ is suggested, since the neutral local anaesthetic benzocaine (1.5 ± 10^-4 m), which is also a membrane stabilizing drug, had the same effects as high Ca²⁺ on the veratridine-induced tetanic fade. The effect of veratrine during tetanic stimulation was partly reversible upon washing. The reversibility was enhanced by high Ca²⁺ or benzocaine.