Rapid atrial flutter treated with rapid atrial stimulation.
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Atrial Flutter↗
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Atrial electrical remodeling by rapid pacing in the isolated rabbit heart: effects of Ca++ and K+ channel blockade.
INTRODUCTION: Electrical remodeling describes atrial electrophysiologic changes that occur following atrial fibrillation. The mechanism(s) responsible for this phenomenon is not well understood. The purpose of this study was to examine the effects of rapid atrial pacing on atrial action potential duration, conduction time and refractoriness in the isolated rabbit heart. The effects of Ca++ and K+ blockade in this model were also studied. METHODS AND RESULTS: Monophasic action potential recordings were made from 12 epicardial atrial sites in 50 isolated perfused rabbit heart preparations. These recordings were analyzed for activation time (AT), 90% action potential duration (APD) and conduction times (CT) measured at a 250 msec cycle length. Atrial effective refractory periods (ERP) were determined at a 200 msec cycle length. All measurements were made at baseline and repeated after 2 hours of biatrial pacing at 250 msec (control group, n = 10) or 2 hours of rapid biatrial pacing (approximately 80 msec) in 4 groups: rapid pacing alone (rapid pacing group); rapid pacing in the presence of 0.1 mM verapamil (verapamil group) for L-type Ca++ channel blockade; rapid pacing with 1 mM 4-aminopyridine (4-AP group) for K+ channel blockade; and rapid pacing with 50 microM nickel chloride (Ni++ group) for T-type Ca++ channel blockade (n = 10 each group). All baseline and post pacing measurements were taken in the presence of Ca++ or K+ blockers for the respective groups. After rapid atrial pacing alone the average APD shortened by 8.2 +/- 10.4 msec compared to 3.6 +/- 12.5 msec shortening for control group (p = 0.002). The shortening of APD was uniform at all recording sites. For the rapid pacing group, CT was unchanged for right to left atrial conduction but shortened significantly for left to right atrial conduction (26.8 +/- 1.9 msec at baseline to 22.3 +/- 4.1 msec post pacing, p = 0.005). Conduction times were unchanged in the control group. The dispersion of repolarization was unchanged by rapid pacing alone. The decrease in APD from baseline to post rapid pacing was similar to the control group for those hearts treated with verapamil and 4-AP (1.5 +/- 12.3 and 4.7 +/- 10.4 msec, respectively, both p > or = 0.18 vs control group). The decrease in APD was significantly greater for the Ni++ group (11.8 +/- 14.3 msec) than for either the control group or rapid pacing group (both p < or = 0.023). The dispersion of repolarization was increased only in the 4-AP group post rapid pacing (41.7 +/- 6.2 msec at baseline to 53.5 +/- 9.6 msec post pacing, p = 0.01). ERPs were unchanged in any of the 5 groups except for a decrease in left atrial ERP in the Ni++ group after rapid pacing (98 +/- 14 msec at baseline to 88 +/- 8 msec post rapid pacing, p = 0.005). CONCLUSIONS: In the isolated rabbit heart model: 1) atrial APD is shortened after rapid pacing; 2) the shortening of APD is attenuated by verapamil and 4-AP but exaggerated by Ni++; 3) atrial conduction times are shortened in a direction specific manner after rapid pacing; and 4) shortening of ERP in this model is measured only in the presence of Ni++. These findings suggest that both L-type Ca++ and 4-AP sensitive channels may participate in atrial electrical remodeling.
4-Aminopyridine↗
Evaluating the American Academy of Pediatrics diagnostic standard for Streptococcus pyogenes pharyngitis: backup culture versus repeat rapid antigen testing.
OBJECTIVE: The American Academy of Pediatrics recommends that all negative rapid diagnostic tests for Streptococcus pyogenes pharyngitis be backed up by culture, which creates a dilemma for clinicians who must make treatment decisions without complete diagnostic information at the time of visit. The use of a follow-up serial rapid antigen test instead of a follow-up culture would provide a more timely result. METHODS: Two swabs were collected from children who were suspected of having S pyogenes pharyngitis. Each swab was used for a culture and an OSOM Ultra Strep A Test rapid antigen test. The gold standard of comparison was defined as the identification of S pyogenes on either of the 2 culture plates. Three diagnostic strategies were evaluated: a single rapid antigen test, a rapid antigen test with follow-up rapid antigen test (rapid-rapid), and a rapid antigen test with follow-up culture (rapid-culture). RESULTS: A total of 210 (23.7%) of 887 throat cultures with matched data were identified with S pyogenes. A single rapid antigen test had a sensitivity of 87.6% (95% confidence interval [CI]: 83.2%-92.1%), the sensitivity of the rapid-rapid follow-up was 91.4% (95% CI: 87.6%-95.2%), and the sensitivity of the rapid-culture follow-up was 95.7% (95% CI: 93.0%-98.5%), which was significantly higher than the others. As shown in Fig 1, when these test strategies were evaluated on a subgroup with clinical symptoms commonly associated with S pyogenes pharyngitis, the sensitivities all increased and were no longer significantly different. None of the strategies reliably exceeded a 95% sensitivity threshold. CONCLUSIONS: The American Academy of Pediatrics strategy for S pyogenes detection in children with pharyngitis, requiring a backup culture for those with negative antigen tests, was not exceeded by any other test strategy; however, a rapid-rapid diagnostic strategy may approximate it with the use of judicious clinical selection of patients.
Antigens, Bacterial↗
Sensitivity and specificity of rapid HIV testing of pregnant women in India.
OBJECTIVE: Efforts to prevent HIV transmission from mother to infants in settings like India may benefit from the availability of reliable methods for rapid and simple HIV screening. Data from India on the reliability of rapid HIV test kits are limited and there are no data on the use of rapid HIV tests for screening of pregnant women. METHODS: Pregnant women attending an antenatal clinic and delivery room in Pune agreed to participate in an evaluation of five rapid HIV tests, including (a) a saliva brush test (Oraquick HIV-1/2, Orasure Technologies Inc.), (b) a rapid plasma test (Oraquick HIV-1/2) and (c) three rapid finger prick tests (Oraquick HIV-1/2; HIV-1/2 Determine, Abbott; NEVA HIV-1/2 Cadila). Results of the rapid tests were compared with three commercial plasma enzyme immunoassay (EIA) tests (Innotest HIV AB EIA, Lab systems/ELISCAN HIV AB EIA, UBI HIV Ab EIA). RESULTS: Between September 2000 and October 1, 2001, 1258 pregnant women were screened for HIV using these rapid tests. Forty-four (3.49%) of the specimens were HIV-antibody-positive by at least two plasma EIA tests. All of the rapid HIV tests demonstrated excellent specificity (96-100%). The sensitivity of the rapid tests ranged from 75-94%. The combined sensitivity and specificity of a two-step algorithm for rapid HIV testing was excellent for a number of combinations of the five rapid finger stick tests. CONCLUSION: In this relatively low HIV prevalence population of pregnant women in India, the sensitivity of the rapid HIV tests varied, when compared to a dual EIA algorithm. In general, the specificity of all the rapid tests was excellent, with very few false positive HIV tests. Based upon these data, two different rapid HIV tests for screening pregnant women in India would be highly sensitive, with excellent specificity to reliably prevent inappropriate use of antiretroviral therapy for prevention of vertical HIV transmission.
Adult↗
Characterization of rapidly labelled ribonucleic acid in Escherichia coli by deoxyribonucleic acid-ribonucleic acid hybridization.
1. Rapidly labelled RNA from Escherichia coli K 12 was characterized by hybridization to denatured E. coli DNA on cellulose nitrate membrane filters. The experiments were designed to show that, if sufficient denatured DNA is offered in a single challenge, practically all the rapidly labelled RNA will hybridize. With the technique employed, 75-80% hybridization efficiency could be obtained as a maximum. Even if an excess of DNA sites were offered, this value could not be improved upon in any single challenge of rapidly labelled RNA with denatured E. coli DNA. 2. It was confirmed that the hybridization technique can separate the rapidly labelled RNA into two fractions. One of these (30% of the total) was efficiently hybridized with the low DNA/RNA ratio (10:1, w/w) used in tests. The other fraction (70% of the total) was hybridized to DNA at low efficiencies with the DNA/RNA ratio 10:1, and was hybridized progressively more effectively as the amount of denatured DNA was increased. A practical maximum of 80% hybridization of all the rapidly labelled RNA was first achieved at a DNA/RNA ratio 210:1 (+/-10:1). This fraction was fully representative of the rapidly labelled RNA with regard to kind and relative amount of materials hybridized. 3. In competition experiments, where additions were made of unlabelled RNA prepared from E. coli DNA, DNA-dependent RNA polymerase (EC 2.7.7.6) and nucleoside 5'-triphosphates, the rapidly labelled RNA fraction hybridized at a low (10:1) DNA/RNA ratio was shown to be competitive with a product from genes other than those responsible for ribosomal RNA synthesis and thus was presumably messenger RNA. At higher DNA/rapidly labelled RNA ratios (200:1), competition with added unlabelled E. coli ribosomal RNA (without messenger RNA contaminants) lowered the hybridization of the rapidly labelled RNA from its 80% maximum to 23%. This proportion of rapidly labelled RNA was not competitive with E. coli ribosomal RNA even when the latter was in large excess. The ribosomal RNA would also not compete with the 23% rapidly labelled RNA bound to DNA at low DNA/RNA ratios. It was thus demonstrated that the major part of E. coli rapidly labelled RNA (70%) is ribosomal RNA, presumably a precursor to the RNA in mature ribosomes. 4. These studies have shown that, when earlier workers used low DNA/RNA ratios (about 10:1) in the assay of messenger RNA in bacterial rapidly labelled RNA, a reasonable estimate of this fraction was achieved. Criticisms that individual messenger RNA species may be synthesized from single DNA sites in E. coli at rates that lead to low efficiencies of messenger RNA binding at low DNA/RNA ratios are refuted. In accordance with earlier results, estimations of the messenger RNA content of E. coli in both rapidly labelled and randomly labelled RNA show that this fraction is 1.8-1.9% of the total RNA. This shows that, if any messenger RNA of relatively long life exists in E. coli, it does not contribute a measurable weight to that of rapidly labelled messenger RNA.
Carbon Isotopes↗
A single five minute period of rapid atrial pacing fails to limit infarct size in the in situ rabbit heart.
OBJECTIVE: Rapid pacing has been shown to precondition the dog heart against ischaemic dysrhythmia. The aim of this study was to determine whether rapid pacing could also limit infarct size. METHODS: Rabbits (n = 5) were rapidly paced via the left atrium at 420-480 beats.min-1. Five min of rapid pacing and 10 min of recovery in sinus rhythm were followed by 45 min of regional ischaemia and 120 min of reperfusion. Control rabbits (n = 9) were treated identically without prior rapid pacing. Infarct size was determined in both groups using tetrazolium and expressed as a percentage of the area at risk demarcated by fluorescent microspheres. In a separate series of experiments, rapidly paced Langendorff perfused rabbit hearts (n = 9) were used to determine coronary flow under perfusion conditions designed to simulate the in vivo situation during rapid pacing. RESULTS: Rapid pacing caused a fall in systolic pressure from 91.4(SEM 4.5) to 47.0(5.9) mm Hg (p < 0.01) and diastolic pressure from 67.2(2.9) to 23.6(3.2) mm Hg (p < 0.01). Both recovered within 30 s of cessation of pacing. During rapid pacing the action potential duration shortened from 192(13) to 128(5) ms (p = 0.01) and developed electrical alternans (n = 4). Following rapid pacing the ECG showed either ST depression or T wave inversion (n = 4). Despite these profound changes, rapid pacing did not reduce infarct size v control [52.7(4.6)% v 60.8(9.1)% of the area at risk, respectively]. The in vitro experiments estimated that rapid pacing would result in a reduction in coronary flow to 44% of that in sinus rhythm without a significant rise in lactate efflux. CONCLUSIONS: In our model, pretreatment with rapid pacing fails to reduce infarct size. The most likely reason for this is that rapid pacing at a rate of 480 beats.min-1 does not cause myocardial ischaemia of sufficient severity to trigger the preconditioning response.
Action Potentials↗
Rapid freezing injury in red spruce: seasonal changes in sensitivity and effects of temperature range.
On calm, cold days in winter, sun-exposed needles of red spruce (Picea rubens Sarg.) may warm 10 to 20 degrees C above ambient air temperature, and undergo rapid (>/= 1 degrees C min(-1)) fluctuations in temperature as light breezes or passing clouds alter the energy balance of the foliage. It has been proposed that the resulting rapid freeze-thaw cycles (freezing stress) cause a type of winter injury in montane red spruce that is characterized by necrosis of sun-exposed foliage. In autumn and winter, we monitored rapid freezing stress response of needle sections from 10 montane red spruce trees by subjecting needles to rapid freezing over the temperature span typically recorded in the field. In autumn, experimental rapid freezing stress produced severe injury only at temperatures considerably lower than expected for that time of year. In winter, rapid freezing caused occasional, moderate injury in fully hardened foliage of trees susceptible to both slow and rapid freezing. Seasonal changes in sensitivity to rapid and slow freezing were correlated, suggesting that environmental factors that are known to affect sensitivity to slow freezing may also affect sensitivity to rapid freezing. Experimental manipulation of the start and end temperatures of rapid freezing stress events showed that moderate to severe needle injury can occur in susceptible trees at temperature spans slightly more extreme than those typically recorded in the field. The extent of injury was similar at different starting temperatures if rapid freezing occurred over the same temperature span. Year-old foliage was consistently less sensitive to rapid freezing stress than current-year foliage, but some year-old foliage was damaged when the rapid freezing stress regime caused severe injury in current-year foliage. We conclude that rapid freeze-thaw cycles can explain light to moderate injury of current-year foliage, but they do not explain the more severe and widespread pattern of foliar damage that has occurred intermittently over at least the last 18 years.
Journal Article↗
Evaluation of urinary rapid test for Helicobacter pylori in general practice.
There is increasing interest in noninvasive tests for the diagnosis of Helicobacter pylori (H. pylori) infection. One such test, a urine-based rapid test kit (RAPIRUN H. pylori Antibody, Otsuka Pharmaceutical Co., Ltd.) for detection of antibody to H. pylori, has been developed and is considered ideal. In addition to its noninvasiveness and safe handling-due to use of urine as a sample-the assay procedure used for the urinary rapid test is very simple. Only 10-20 minutes are required to complete an assay, and no instruments are needed. The aim of this study was to examine the clinical usefulness of this urine-based rapid test. A total of 189 patients, including 76 patients with gastroduodenal disease, were recruited. A pair of random single-void urine and serum samples was collected from each of the 189 patients, and antibody to H. pylori in the urine and serum samples was measured using the urine-based rapid test kit and three commercially available serum-based ELISA kits. For the patients with gastroduodenal disease, invasive diagnostic methods using endoscopic biopsy specimens such as culture, histology, and rapid urease test were also performed. The sensitivity, specificity, and accuracy of the urinary rapid test were evaluated on the basis of the three serum ELISA results or the invasive diagnostic results. In addition, various urinalyses were performed, and the effects of substances existing in urine on the urinary rapid test results were examined. Of the 189 patients, the urinary rapid test was positive for 110 (58.2%), negative for 78 (41.3%), and invalid for only one patient (0.5%). Based on the three serum-based ELISA results, the sensitivity, specificity, and accuracy of the urinary rapid test were 93.7, 88.9, and 92.2%, respectively. On the basis of the biopsy-based test results, the sensitivity of the urinary rapid test was 100% and its accuracy (95.2%) was equivalent or superior to that of each serum-based ELISA. In addition, no significant differences were observed between groups positive and negative on urinary rapid testing in any urinalysis parameter examined. The novel urinary rapid test kit evaluated in this study enables simple, rapid, and accurate diagnosis of H. pylori infection, and is an ideal test method for point-of-care testing.
Adult↗
A rapid troponin I assay is not optimal for determination of troponin status and prediction of subsequent cardiac events at suspicion of unstable coronary syndromes.
BACKGROUND: Troponin is a specific marker of myocardial damage. For early prediction of coronary events in patients with suspicion of acute coronary syndromes the assay also needs to be highly sensitive. METHODS AND RESULTS: A rapid troponin I assay was performed prior to inclusion in 4447 acute coronary syndrome patients in the GUSTO-IV trial. A quantitative troponin T analysis was later performed on blood samples obtained at randomization by a central laboratory. There was an agreement between the rapid troponin I assay and troponin T (< or =/>0.1 microg/l) in 3596 (80.9%) patients. A positive rapid troponin I was identifying any elevation of troponin T (>0.01 microg/l) in 1990 patients (90.4%) whereas a negative rapid troponin I was corresponding to negative troponin T (< or =0.01 microg/l) in only 1217 patients (54.2%). Patients with a positive versus negative rapid troponin I had an increased risk of death or myocardial infarction at 30 days (9.3 vs. 5.9%; odds ratio, O.R. 1.64; 95% confidence interval, 1.31-2.06). Troponin T elevation (>0.1 microg/l) provided a better (10.5 v. 4.9%, O.R. 2.26; C.I. 1.79-2.85) risk stratification. Regardless of a positive or a negative rapid troponin I, the troponin T result (>0.1 vs. < or =0.1 microg/l) stratified the patients into high and low risk of events at 30 days, (10.3 vs. 5.7%, P=0.002) and (11.5 vs. 4.8%, P<0.001), respectively. CONCLUSION: In a population with non-ST elevation acute coronary syndrome a positive rapid troponin I assay is a specific indicator of troponin elevation and a predictor of early outcome. However, a negative rapid troponin I is not a reliable indicator of the absence of myocardial damage and does not indicate a low risk of subsequent cardiac events. A rapid troponin I assay was performed prior to inclusion in 4447 acute coronary syndrome patients in the GUSTO-IV trial and related to a centrally analyzed quantitative troponin T test. A positive rapid troponin I was well corresponding to any elevation of troponin T (>0.01 microg/l) and predicted an unfavorable outcome at 30 days. However, a negative rapid troponin I was corresponding to troponin T < or =0.01 microg/l in only half of the patients. Troponin T >0.1 microg/l vs. < or =0.1 microg/l provided a better risk stratification than the rapid troponin I result. For patients with troponin T elevation (>0.1 microg/l) the 30 day event rate was high regardless of the rapid troponin I result.
Abciximab↗
Multisite data reanalysis of the validity of rapid cycling as a course modifier for bipolar disorder in DSM-IV.
OBJECTIVE: The validity of rapid cycling as a distinct course modifier for bipolar disorder was assessed by comparing patients with and without a history of rapid cycling (4 or more affective episodes in 12 months) on demographic, clinical, family history, and outcome variables. These data were also used to formulate operational criteria for the modifier. METHOD: Data on subjects with rapid-cycling (N = 120) and nonrapid-cycling (N = 119) bipolar disorder from four sites were pooled and analyzed by using case-control and historical cohort methods. RESULTS: The rapid-cycling group contained more women and more subjects from higher social classes than the nonrapid-cycling group. Family history did not differ between the groups. The diagnosis had predictive validity in that the rapid-cycling patients had more episodes than the nonrapid-cycling patients during prospective follow-up. The relationship between gender and episode frequency supported the validity of the cutoff point of 4-8 episodes per year. The data regarding whether patients with rapid cycling based on truncated episodes more closely resembled rapid-cycling or nonrapid-cycling patients were equivocal. Patients whose only rapid cycling was associated with antidepressants resembled spontaneously rapid-cycling patients, while the majority of spontaneously rapid-cycling patients also had periods of antidepressant-associated rapid cycling. CONCLUSIONS: The validity of rapid cycling as a distinct course modifier for bipolar disorder is supported by differences in gender, prospectively assessed outcome, and perhaps social class between rapid-cycling and nonrapid-cycling patients. The relationship of gender to episode frequency supports the cutoff of 4 or more episodes per year.
Adult↗
A proposed approach to recognise "near-remission" quantitatively without formal joint counts or laboratory tests: a patient self-report questionnaire routine assessment of patient index data (RAPID) score as a guide to a "continuous quality improvement" s.
A proposed approach is presented to recognise a status of "near-remission" in a patient with rheumatoid arthritis (RA) on the basis of patient self-report questionnaire data without formal joint counts or laboratory tests. Indices of patient-reported outcome (PRO) measures distinguish active from control treatments in RA clinical trials at levels similar to American College of Rheumatology (ACR) or disease activity score (DAS) 28 improvement levels. PRO measures on a multidimensional health assessment questionnaire (MDHAQ) can be compiled into a routine assessment of patient index data (RAPID) score. RAPID 3 includes the three PRO measures from the ACR Core Data Set - physical function, pain, and global estimate. RAPID 4 adds a self-report joint count from a rheumatoid arthritis disease activity index (RADAI). RAPID 5 adds a physician estimate of global status. RAPID cores may be classified into four preliminary proposed categories, as "near-remission" (0-1), "low severity" (1.01-2), "moderate severity" (2.01-4), and "high severity" (> 4), analogous to the four categories of the DAS28 of "remission" (< 2.6), as well as "low" (2.6-3.19), "moderate" (3.2-5.1), and "high" (> 5.1) disease activity. RAPID scores are correlated significantly with DAS28 (rho = 0.64-0.67, p < 0.001), and about 75% of patients with DAS < 2.6 have RAPID scores < 2, while about 75% of patients with DAS > 5.1 have RAPID scores > 4. RAPID data are available on one side of one page, and are feasible to collect in standard clinical care. RAPID 3 scores may be calculated in about 10 seconds, and RAPID 4 and RAPID 5 scores in 20 to 30 seconds. RAPID scores every 3 months or more on simple flowsheets can be a basis for a "continuous quality improvement" strategy in standard clinical care to recognise a need for aggressive therapy, an inadequate response to a therapy, and "near- remission" status.
Activities of Daily Living↗
A family history study of rapid-cycling bipolar disorder.
Previous studies have yielded mixed evidence as to whether rapid-cycling bipolar disorder (four or more episodes per year) is associated with a distinctive pattern of patient characteristics and familial aggregation of affective disorder. In this study, Family History Research Diagnostic Criteria (FH-RDC) were used to interview 165 patients with rapid-cycling bipolar disorder, non-rapid-cycling bipolar disorder, or recurrent unipolar depressive disorder about the psychiatric history of 812 adult first-degree relatives. In a validity study, FH-RDC diagnoses were demonstrated to agree reasonably well with best-estimate diagnoses by two psychiatrists/psychologists, based on direct interviews with the Structured Clinical Interview for DSM-III-R. Relatives of patients with recurrent unipolar depression were less likely to have bipolar disorder and more likely to have unipolar depression than were relatives of rapid-cycling or non-rapid-cycling bipolar patients. Rapid-cycling patients were younger and more likely to be female than non-rapid-cycling patients. The relatives of rapid cyclers did not differ significantly from those of non-rapid cyclers in the prevalence of bipolar disorder, unipolar disorder, rapid-cycling bipolar disorder, or substance abuse. However, there were nonsignificant trends for the relatives of rapid-cycling bipolar patients, compared with those of non-rapid-cycling bipolar patients, to have more substance abuse and less bipolar disorder given the presence of affective disorder.
Adult↗
Evaluation of a new reagent strip rapid urease test for detection of Helicobacter pylori infection.
BACKGROUND: Rapid urease tests are commonly used as a convenient method to detect Helicobacter pylori infection. Our previous experiments demonstrated enhanced efficacy of agar gel rapid urease test compared with reagent strip rapid urease tests. We evaluated the efficacy of PyloriTek, a new reagent strip rapid test for detecting H. pylori infection. METHODS: Gastric antral mucosal biopsy specimens were obtained for comparison between agar gel rapid urease tests and PyloriTek (200 specimens). The rapid urease test to be used first was selected randomly. H. pylori status was determined using the Genta stain. Culture was performed to confirm H. pylori status when false rapid urease tests were suspected. RESULTS: One hundred patients were studied; 68 had H. pylori infection. There were two false-negative and one false-positive PyloriTek when scored at 1 hour, compared with only one false-positive and no false-negative tests at 2 hours. With the agar gel rapid urease tests, there were no false-positive tests and 5 false-negative tests when scored at 1 hour, 2 false-negative tests at 12 hours and 1 at 24 hours; there were no false-positive tests. At 1 hour, 3% (95% CI = 1% to 9%) of PyloriTek tests had an erroneous categorization of H. pylori status compared with 5% for the agar gel rapid urease tests (95% CI = 1.6% to 11%) (p > 0.7). CONCLUSION: The new reagent strip rapid urease test, PyloriTek, is rapid and comparable in accuracy to agar gel rapid urease tests for detecting H. pylori Infection.
Adult↗
The disconnected brain stem does not support rapid eye movement sleep rebound following selective deprivation.
STUDY OBJECTIVES: To determine whether the brain stem can independently support the processes of rapid eye movement sleep rebound and pressure that follow deprivation. DESIGN: Cats with a brain-stem separation from the forebrain were compared to intact subjects on their response to rapid eye movement sleep deprivation. PARTICIPANTS: Eight adult mongrel cats of both sexes. INTERVENTIONS: All cats had electrodes implanted for polygraphic recordings, and 4 subjects sustained a mesencephalic transection. Weeks later, a 24-hour undisturbed sleep-wakefulness recording session was performed, and the next day, a similar session started with a 6-hour deprivation period, which was followed by 18 hours of undisturbed sleep. MEASUREMENTS AND RESULTS: Deprivation produced 90.1% and 87.8 % losses of rapid eye movement sleep time in intact and decerebrate cats, respectively. However, no significant changes in non-rapid eye movement sleep, drowsiness, or waking time percentages were seen in either group of animals when comparing the 6-hour time blocks of the deprivation and baseline sessions, indicating selective rapid eye movement sleep deprivation. During the 6-hour block following deprivation, rapid eye movement sleep time increased a significant 34.6% in intact cats while, in contrast, there was no rapid eye movement sleep rebound in decerebrate animals. The number of aborted episodes of rapid eye movement sleep during deprivation exceeded the number of episodes during the same period of the baseline day by 3 and 5 folds in intact and decerebrate cats, respectively, indicating an increase in rapid eye movement sleep pressure. CONCLUSIONS: Rebound in rapid eye movement sleep after deprivation cannot be sustained by the brain stem alone; in contrast, rapid eye movement sleep pressure persisted in the decerebrate cat, demonstrating that this process does not depend on descending forebrain influences. This indicates that rebound and pressure are 2 different components of the recovery process after rapid eye movement sleep deprivation and that, as such, are likely controlled by different mechanisms.
Animals↗
On-site HIV testing in resource-poor settings: is one rapid test enough?
OBJECTIVE: To determine the feasibility, accuracy and cost-effectiveness of a rapid, on-site, HIV testing strategy in a rural hospital, and to assess its impact on test turnaround time and the proportion of patients post-test counselled. DESIGN: Prospective comparison of two testing strategies [double rapid test on-site versus central enzyme-linked immunosorbent assay (ELISA)-based testing], and an economic evaluation. SETTING: Hlabisa Hospital, a rural South African district hospital. PATIENTS: A total of 454 consecutive adult inpatients requiring and consenting to HIV testing as part of their clinical management. MAIN OUTCOME MEASURES: Concordance between rapid tests, and between the rapid and ELISA strategies, test turnaround time, proportion of patients post-test counselled, and cost-effectiveness. RESULTS: HIV seroprevalence was 49.6%. Both rapid tests were concordant in all patients [one-sided 95% confidence interval (CI) of probability, 99.3-100]. The rapid strategy was 100% sensitive (95% CI, 97.9-100) and 99.6% specific (95% CI, 97.2-100) compared with the ELISA strategy. The mean interval between ordering a test and post-test counselling fell from 21 days prior to the introduction of the rapid test strategy to 4.6 days after its introduction (P < 0.00001). The proportion of patients post-test counselled increased to 96% from 17% after the introduction of the rapid test strategy (P < 0.00001). By using a double rapid test strategy the cost per patient post-test counselled was almost halved to US$ 11. Accuracy of the rapid strategy was not substantially increased by performing two tests. CONCLUSION: In high prevalence, resource-poor settings, rapid, on-site HIV testing is feasible, accurate and highly cost-effective, substantially increasing the number of patients post-test counselled. A single rapid test may be sufficient.
AIDS Serodiagnosis↗
Small hemodynamic effect of typical rapid volume infusions in critically ill patients.
OBJECTIVES: To determine what volumes are commonly used for rapid volume infusions in critically ill patients admitted to the intensive care unit (ICU) for > 12 hrs; and to determine the effectiveness of a typical rapid volume infusion in producing hemodynamic change and increasing left ventricular end-diastolic volume. DESIGN: A prospective survey of clinical practice (part 1) and a prospective clinical investigation (part 2). SETTING: Two hospital ICUs (11 and six beds) of which one is university affiliated. PATIENTS: Critically ill patients admitted to the ICU for > 12 hrs. INTERVENTIONS: Infusion of 500 mL of normal saline over 5 to 10 mins. MEASUREMENTS AND MAIN RESULTS: For 1 month, we recorded the volume and composition of all volume infusions given as a rapid bolus in patients admitted to the ICU for > 12 hrs. We then measured the effected the median rapid volume infusion in a subset of 13 patients by measuring hemodynamics (using arterial and pulmonary artery flotation catheters) and left ventricular end-diastolic area (using transgastric short-axis views from transesophageal echocardiograms). During 470 patient days, 159 rapid volume infusions were administered. The average rapid volume infusion administered was 390 +/- 160 mL (median 500; interquartile range 250 to 500). Crystalloid solutions were used for two thirds of the rapid volume infusions and colloid solutions were used for one third of the rapid volume infusions. The rapid volume infusion of 500 mL of saline did not significantly increase mean arterial pressure (78.0 +/- 11.9 to 79.3 +/- 14.6 mm Hg), cardiac index (4.3 +/- 1.7 to 4.6 +/- 1.8 L/min/m2), right atrial pressure (11.1 +/- 3.8 to 12.4 +/- 3.3 mm Hg), left ventricular end-diastolic area (8.6 +/- 1.7 to 9.1 +/- 1.8 cm2/m2), or left ventricular end-systolic area (3.5 +/- 1.5 to 3.6 +/- 1.5 cm2/m2). Pulmonary artery occlusion pressure increased slightly but significantly from 12.9 +/- 3.4 to 14.7 +/- 3.3 mm Hg (p < .05). CONCLUSIONS: After patients are admitted to the ICU for > 12 hrs, rapid volume infusions are common therapeutic interventions but the rapid volume infusions are typically small. The effect of a typical rapid volume infusion on hemodynamics and left ventricular areas in these patients is surprisingly small.
Adult↗
A new protocol for maxillary protraction in cleft patients: repetitive weekly protocol of alternate rapid maxillary expansions and constrictions.
OBJECTIVE: It was hypothesized that, through a repetitive weekly protocol of Alternate Rapid Maxillary Expansions and Constrictions (Alt-RAMEC), the maxilla in cleft patients could be protracted more effectively than with a single course of rapid maxillary expansion (RME). METHODS: Twenty-six consecutive unilateral cleft lip and palate patients at the age of mixed dentition were included in this prospective clinical study. The rapid maxillary expansion group included the first 16 consecutive patients undergoing 1 week of rapid maxillary expansion (1 mm/day) followed by 5 months, 3 weeks of maxillary protraction. The Alternate Rapid Maxillary Expansions and Constrictions group included the next 10 consecutive patients undergoing 9 weeks of Alternate Rapid Maxillary Expansions and Constrictions followed by 3 months, 3 weeks of maxillary protraction. Daily activation of the weekly expansion or constriction was 1.0 mm. Two-hinged expanders and intraoral maxillary protraction springs were used in both groups. Treatment results were evaluated cephalometrically. RESULTS: The amount of maxillary anterior displacement by the 2-hinged expander in the Alternate Rapid Maxillary Expansions and Constrictions group was 3.0 +/- 0.9 mm at A point, significantly greater than the 1.6 +/- 1.0 mm in the rapid maxillary expansion group. The amount of maxillary advancement with intraoral protraction springs in the Alternate Rapid Maxillary Expansions and Constrictions group was 2.9 +/- 1.9 mm at A point, significantly greater than the 0.9 +/- 1.1 mm in the rapid maxillary expansion group. The overall amount of maxillary advancement in the Alternate Rapid Maxillary Expansions and Constrictions group was 5.8 +/- 2.3 mm at A point. This result remained stable, without significant relapse after 2 years. CONCLUSIONS: Maxillary protraction using the 2-hinged expander, a repetitive weekly protocol of Alternate Rapid Maxillary Expansions and Constrictions, and intraoral protraction springs is most effective, with stable results at 2-year follow-up.
Cephalometry↗
Rapid switching of mood in families with multiple cases of bipolar disorder.
BACKGROUND: Heterogeneity within the diagnostic construct of bipolar disorder is most likely an obstacle to discovering its causes. Phenomena in the bipolar spectrum, including rapid cycling, cyclothymia, and affective instability of borderline personality, may be important markers of etiologic heterogeneity. Rapid switching of mood may be central to these phenomena. METHODS: We performed a case-control study, using diagnostic data from a multisite bipolar disorder linkage study, to explore clinical and demographic factors potentially related to rapid switching in bipolar disorder. Participants were 18 years or older and members of a family in which 2 or more first-degree relatives had bipolar disorder. Of 718 individuals interviewed and diagnosed as having bipolar disorder, 603 gave sufficient information about rapid switching and thus constituted the study group (60% female; mean age, 41 years; and mean education level, 13.8 years). RESULTS: Rapid switching of mood was reported by 44% of interviewees and was associated with early age at onset of bipolar disorder, higher risk of anxiety and substance abuse or dependence comorbidity, suicide attempts, antidepressant drug use, and having a relative with rapid switching. CONCLUSIONS: Rapid switching is associated with a complex clinical course of bipolar disorder. These results extend previous associations among rapid switching, anxiety, substance abuse, and early onset of bipolar disorder to a family study population. Rapid switching of mood seems to be the core phenomenon behind several variants of non-DSM-IV rapid cycling, DSM-III-R mixed states, and borderline personality disorder and the link connecting comorbidity, suicide, and early onset of bipolar disorder. Further biological investigation of the rapid-switching phenomenon is justified on epidemiologic grounds.
Adult↗