A discrete choice experiment to assess people living with HIV's (PLWHIV's) preferences for GP or HIV clinic appointments

OBJECTIVES

To understand which aspects of general practitioner (GP) and HIV clinic appointments people living with HIV (PLWHIV) most value when seeking advice for new health problems.

METHODS

A discrete choice experiment using a convenience sample of people diagnosed with HIV. Participants were recruited from 14 general HIV clinics in the South East of England between December 2014 and April 2015. ORs were calculated using conditional logit (CLOGIT) and latent class models (LCMs).

RESULTS

A total of 1106 questionnaires were returned. Most participants were male (85%), white (74%) and were men who have sex with men (69%). The CLOGIT analysis showed people particularly valued shorter appointment waiting times (ORs between 1.52 and 3.62, p<0.001 in all instances). The LCM analysis showed there were two distinct classes, with 59% and 41% of respondents likely to be in each. The first class generally preferred GP to HIV clinic appointments and particularly valued 'being seen quickly'. For example, they had strong preferences for shorter appointment waiting times and longer GP opening hours. People in the second class also valued shorter waiting times, but they had a strong general preference for HIV clinic rather than GP appointments.

CONCLUSIONS

PLWHIV value many aspects of care for new health problems, particularly short appointment waiting times. However, they appear split in their general willingness to engage with GPs.

Daytime variability of baroreflex function in patients with obstructive sleep apnoea: implications for hypertension

Obstructive events during sleep in patients with obstructive sleep apnoea (OSA) cause large alterations in blood pressure, and this may lead to changes in baroreflex function with implications for long-term blood pressure control. This study examined the daytime variations in the responses to carotid baroreceptor stimulation in OSA patients. We determined the cardiac and vascular responses every 3 h between 09.00 and 21.00 h in 20 patients with OSA, using graded suctions and pressures applied to a neck collar. These responses were plotted against estimated carotid sinus pressures and, from these plots, baroreflex sensitivities and operating points were taken as the maximal slopes and the corresponding carotid sinus pressures, respectively. We found that at 09.00 h, sensitivity for the control of vascular resistance was at its lowest (--1.2 +/- 0.2% mmHg(-1), compared with --1.9 +/- 0.3% mmHg(-1) at 12.00 h, P < 0.02) and operating point for control of mean arterial pressure was at its highest (101.1 +/- 5.8 mmHg, compared with 94.1 +/- 5.8 mmHg at 12.00 h, P < 0.05). This is in contrast to previous data from normal subjects, in whom sensitivity was highest and operating point lowest at 09.00 h. We suggest that the higher baroreflex sensitivity and lower operating point seen in the mornings in normal subjects may provide a protective mechanism against hypertension and that this protection is absent in patients with OSA. It is possible that the reduced reflex sensitivity and increased operating point in the mornings may actually promote hypertension.

Interaction of chemoreceptor and baroreceptor reflexes by hypoxia and hypercapnia - a mechanism for promoting hypertension in obstructive sleep apnoea

Asphyxia, which occurs during obstructive sleep apnoeic events, alters the baroreceptor reflex and this may lead to hypertension. We have recently reported that breathing an asphyxic gas resets the baroreceptor-vascular resistance reflex towards higher pressures. The present study was designed to determine whether this effect was caused by the reduced oxygen tension, which affects mainly peripheral chemoreceptors, or by the increased carbon dioxide, which acts mainly on central chemoreceptors. We studied 11 healthy volunteer subjects aged between 20 and 55 years old (6 male). The stimulus to the carotid baroreceptors was changed using graded pressures of -40 to +60 mmHg applied to a neck chamber. Responses of vascular resistance were assessed in the forearm from changes in blood pressure (Finapres) divided by brachial blood flow velocity (Doppler) and cardiac responses from the changes in RR interval and heart rate. Stimulus-response curves were defined during (i) air breathing, (ii) hypoxia (12% O(2) in N(2)), and (iii) hypercapnia (5% CO(2) in 95% O(2)). Responses during air breathing were assessed both prior to and after either hypoxia or hypercapnia. We applied a sigmoid function or third order polynomial to the curves and determined the maximal differential (equivalent to peak sensitivity) and the corresponding carotid sinus pressure (equivalent to 'set point'). Hypoxia resulted in an increase in heart rate but no significant change in mean blood pressure or vascular resistance. However, there was an increase in vascular resistance in the post-stimulus period. Hypoxia had no significant effect on baroreflex sensitivity or 'set point' for the control of RR interval, heart rate or mean arterial pressure. Peak sensitivity of the vascular resistance response to baroreceptor stimulation was significantly reduced from -2.5 +/- 0.4 units to -1.4 +/- 0.1 units (P < 0.05) and this was restored in the post-stimulus period to -2.6 +/- 0.5 units. There was no effect on 'set point'. Hypercapnia, on the other hand, resulted in a decrease in heart rate, which remained reduced in the post-stimulus period and significantly increased mean blood pressure. Baseline vascular resistance was significantly increased and then further increased in the post-control period. Like hypoxia, hypercapnia had no effect on baroreflex control of RR interval, heart rate or mean arterial pressure. There was, also no significant change in the sensitivity of the vascular resistance responses, however, 'set point' was significantly increased from 74.7 +/- 4 to 87.0 +/- 2 mmHg (P < 0.02). This was not completely restored to pre-stimulus control levels in the post-stimulus control period (82.2 +/- 3 mmHg). These results suggest that the hypoxic component of asphyxia reduces baroreceptor-vascular resistance reflex sensitivity, whilst the hypercapnic component is responsible for increasing blood pressure and reflex 'set point'. Hypercapnia appears to have a lasting effect after the removal of the stimulus. Thus the effect of both peripheral and central chemoreceptors on baroreflex function may contribute to promoting hypertension in patients with obstructive sleep apnoea.

Effects of simulated obstructive sleep apnoea on the human carotid baroreceptor-vascular resistance reflex

Obstructive sleep apnoea (OSA), which is characterized by periodic inspiratory obstruction, is associated with hypertension and possibly with changes in the baroreceptor reflex. In this investigation we induced changes in inspiratory resistance and in inspiratory oxygen and carbon dioxide content, which simulate some of the changes in OSA, to determine whether this caused changes in the gain or setting of the carotid baroreflex. In eight healthy subjects (aged 21-62 years) we changed the stimulus to carotid baroreceptors, using neck chambers and graded pressures of -40 to +60 mmHg, and assessed vascular resistance responses in the brachial artery from changes in blood pressure (Finapres) divided by brachial artery blood flow velocity (Doppler ultrasound). Stimulus-response curves were defined during (a) sham (no additional stimulus), (b) addition of an inspiratory resistance (inspiratory pressure -10 mmHg), (c) breathing asphyxic gas (12% O(2), 5% CO(2)), and (d) combined resistance and asphyxia. Sigmoid or polynomial functions were applied to the curves and maximum differentials (equivalent to peak gain) and the corresponding carotid pressures (equivalent to 'set point') were determined. The sham test had no effect on either gain or 'set point'. Inspiratory resistance alone had no effect on blood pressure and did not displace the curve. However, it reduced gain from -3.0 +/- 0.6 to -2.1 +/- 0.4 units (P < 0.05). Asphyxia alone did increase blood pressure (+7.0 +/- 1.1 mmHg, P < 0.0005) and displaced the curve to higher pressures by +16.8 +/- 2.1 mmHg (P < 0.0005). However, it did not affect gain. The combination of resistance and asphyxia both reduced gain and displaced the curve to higher pressures. These results suggest that inspiratory resistance and asphyxia cause changes in the baroreceptor reflex which could lead to an increase in blood pressure. These changes, if sustained, could provide a mechanism linking hypertension to obstructive sleep apnoea.

Cardiovascular regulation in the period preceding vasovagal syncope in conscious humans

To study cardiovascular control in the period leading to vasovagal syncope we monitored beat-to-beat blood pressure, heart rate (HR) and forearm blood flow in 14 patients with posturally related syncope, from supine through to tilt-induced pre-syncope. Signals of arterial blood pressure (BP) from a Finapres photoplethysmograph and an electrocardiograph (ECG) were fed into a NeuroScope system for continuous analysis. Non-invasive indices of cardiac vagal tone (CVT) and cardiac sensitivity to baroreflex (CSB) were derived on a beat-to-beat basis from these data. Brachial vascular resistance (VR) was assessed intermittently from brachial blood flow velocity (Doppler ultrasound) divided by mean arterial pressure (MAP). Patients underwent a progressive orthostatic stress test, which continued to pre-syncope and consisted of 20 min head-up tilt (HUT) at 60 deg, 10 min combined HUT and lower body suction (LBNP) at -20 mmHg followed by LBNP at -40 mmHg. Pre-syncope was defined as a fall in BP to below 80 mmHg systolic accompanied by symptoms. Baseline supine values were: MAP (means +/- S.E.M.) 84.9 +/- 3.2 mmHg; HR, 63.9 +/- 3.2 beats min-1; CVT, 10.8 +/- 2.6 (arbitrary units) and CSB, 8.2 +/- 1.6 ms mmHg-1. HUT alone provoked pre-syncope in 30 % of the patients whilst the remaining 70 % required LBNP. The cardiovascular responses leading to pre-syncope can be described in four phases. Phase 1, full compensation: where VR increased by 70.9 +/- 0.9 %, MAP was 89.2 +/- 3.8 mmHg and HR was 74.8 +/- 3.2 beats min-1 but CVT decreased to 3.5 +/- 0.5 units and CSB to 2.7 +/- 0.4 ms mmHg-1. Phase 2, tachycardia: a progressive increase in heart rate peaking at 104.2 +/- 5.1 beats min-1. Phase 3, instability: characterised by oscillations in BP and also often in HR; CVT and CSB also decreased to their lowest levels. Phase 4, pre-syncope: characterised by sudden decreases in arterial blood pressure and heart rate associated with intensification of the symptoms of pre-syncope. This study has given a clearer picture of the cardiovascular events leading up to pre-syncope. However, the mechanisms behind what causes a fully compensated system suddenly to become unstable remain unknown.

Effects of head-up tilting on baroreceptor control in subjects with different tolerances to orthostatic stress

During orthostatic stress, an increase in peripheral vascular resistance normally results in arterial blood pressure being well maintained, despite a decrease in cardiac output. The present study was undertaken to determine whether the sensitivity of the carotid baroreceptor reflex was increased during orthostatic stress and whether failure to develop this increase was associated with poor orthostatic tolerance. Three groups of subjects were studied: asymptomatic controls; patients investigated for suspected posturally related syncope but who had normal responses to an orthostatic stress test (normal patients); and patients who were shown to have low orthostatic tolerance (early fainters). We determined responses of R-R interval and forearm vascular resistance (mean arterial pressure/brachial artery velocity by Doppler ultrasonography) to the loading and unloading of carotid baroreceptors by application of pressures of -30 and +30 mmHg to a chamber fitted over the neck. Responses were determined after 20 min of supine rest and after 10 min of head-up tilt at 60 degrees. Responses of cardiac interval were not significantly different between the three groups, and they were not altered by the postural change. Vascular responses also did not differ between the groups during supine rest. However, in healthy volunteers and in normal patients, responses to both neck suction and pressure were significantly enhanced during head-up tilt. In controls, responses to suction were increased by tilt from 0.04+/-0.1 to -1.01+/-0.2%.mmHg(-1) (means+/-S.E.M.; P<0.001) and those to neck pressure from -0.6+/-0.3 to -3.1+/-1.1%.mmHg(-1) (P<0.05). In the normal patients, the corresponding changes were: during suction, from -0.2+/-0.1 to -0.7+/-0.1%.mmHg(-1) (P<0.05); during pressure, from -0.7+/-0.1 to -1.5+/-0.3%.mmHg(-1) (P<0.05). In contrast, in patients with low orthostatic tolerance, posture had no effect on the reflex (neck suction, from -0.3+/-0.1 to -0.3+/-0.1%.mmHg(-1); neck pressure, from -1.0+/-0.3 to -0.9+/-0.2%.mmHg(-1)). We suggest that an increase in the sensitivity of the carotid baroreceptor/vascular resistance reflex may be important in the maintenance of blood pressure during orthostatic stress, and that failure of this to occur in patients with posturally related syncope may go some way towards explaining their poor orthostatic tolerance.

Carotid baroreceptor reflexes in humans during orthostatic stress

Orthostatic stress, including standing, head-up tilting and lower body suction, results in increases in peripheral vascular resistance but little or no change in mean arterial pressure. This study was undertaken to determine whether the sensitivity of the carotid baroreceptor reflex was enhanced during conditions of decreased venous return. We studied eight healthy subjects and determined responses of pulse interval (ECG) and forearm vascular resistance (mean finger blood pressure divided by Doppler estimate of brachial artery blood velocity) to graded increases and decreases in carotid transmural pressure, effected by a neck suction/pressure device. Responses were determined with and without the application of lower body negative pressure (LBNP) at -40 mmHg. Stimulus-response curves were determined as the responses to graded neck pressure changes and the differential of this provided estimates of reflex sensitivity. Changes in carotid transmural pressure caused graded changes in R-R interval and vascular resistance. The cardiac responses were unaffected by LBNP. Vascular resistance responses, however, were significantly enhanced during LBNP and the peak gain of the reflex was increased from 1.2 +/- 0.3 (mean +/- S.E.M.) to 2.2 +/- 0.3 units (P < 0.05). The increased baroreflex gain may contribute to maintenance of blood pressure during orthostatic stress and limit the pressure decreases during prolonged periods of such stress.

Diagnosis of neonatal pig diarrhea

To be effective, swine practitioners should develop a unit health program. Development should involve unit managers, owners, and employees involved in day-to-day operations. Emphasis on training personnel and management to reduce disease and collection of accurate records is necessary. Routine diagnostics are needed to solve disease problems. Communication with laboratory personnel to ascertain what samples are needed for diagnosis of particular problems cannot be overemphasized. General diagnosis of disease problems outlined by Vinson can be similarly followed within the specifics of diarrheal problems within units. 1. Observe symptoms exhibited by pigs, i.e., huddling, fecal material around perineum, extreme thirst, etc. 2. Evaluate the degree of morbidity and potential production losses. 3. Analyze possible specific causes of symptoms, i.e., environmental cleanliness, affected litter distribution, age of affected neonates, and other populations affected. 4. Examine live animals, i.e., obtain serum samples from a random population, take rectal temperatures of affected neonates, and evaluate fecal pH. 5. Necropsy dead or dying pigs [that] appear to represent the problem. 6. Submit live pigs or appropriate tissues from necropsied pigs to a diagnostic laboratory. 7. Re-evaluate environmental conditions that may be contributing to the problem (remember, unit employees are a part of the pigs' environment). 8. Evaluate management procedures contributing to the disease problem, i.e., lack of adherence to all-in all-out, rapid turn-around decreasing cleaning time etc. Following this format and communicating with diagnosticians should provide for positive results for the producers both entities serve.

Absence of tuberculosis in free-ranging deer in Nebraska

Lymph nodes from 271 white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) in Nebraska (USA) were examined microscopically for tuberculoid lesions. Lymph nodes lesions in at least one node were found in 12 deer. Lesions were examined with Zeihl-Neelson acid fast stains and by polymerase chain reactions using M. bovis specific probes. No evidence of tuberculosis was found. The small granulomatous lesions were likely caused by other bacteria.

In vivo detection of porcine reproductive and respiratory syndrome virus RNA by in situ hybridization at different times postinfection

We studied the distribution of porcine reproductive and respiratory syndrome virus (PRRSV) RNA in tissues by in situ hybridization at different times postinfection (p.i.). The probe used for in situ hybridization was prepared by reverse transcription of PRRSV RNA, followed by PCR amplification of the cDNA. The sequence amplified corresponded to 433 bp from PRRSV open reading frame 7, which is contained in the nucleocapsid protein gene and which is highly conserved in both European and American strains (H. Mardassi, L. Wilson, S. Mounir, and S. Dea, J. Clin. Microbiol. 32:2197-2203, 1994). An immunohistochemical technique was used to detect PRRSV antigen in tissue from virus-infected animals by using a monoclonal antibody specific for the PRRSV nucleocapsid protein (E.A. Nelson, J. Christopher-Hennings, T. Drew, G. Wensvoort, J.E. Collins, and D.A. Benfield, J. Clin. Microbiol. 31:3184-3189, 1993). The detection of PRRSV RNA was conducted in tissues of 6-week-old pigs that had been infected with one of three different field PRRSV isolates and collected at times ranging from 4 to 42 days p.i. Hybridization signals specific for PRRSV RNA were detected in lung, lymphoid tissues, alveolar macrophages (obtained by lavage at the time of necropsy), Peyer's patches, and kidney. The PRRSV-positive cells in these tissues appeared to be predominantly macrophages. In lung tissue we also obtained evidence suggesting the involvement of type II pneumocytes in the replication of PRRSV. During the acute period of infection there was a close correlation between the detection of RNA and the detection of nucleocapsid protein in individual cells. At later times p.i. (28 and 42 days p.i.), instead, more cells containing only PRRSV RNA than those containing PRRSV RNA and also expressing PRRSV nucleocapsid protein were detected. These results suggest that PRRSV RNA might persist in the tissues of infected animals for a longer time than PRRSV antigen expression.

Porcine reproductive and respiratory syndrome: NEB-1 PRRSV infection did not potentiate bacterial pathogens

A 2-phase study was conducted to evaluate the ability of the NEB-1 strain of porcine reproductive and respiratory syndrome virus (PRRSV) to potentiate common bacterial pathogens of swine. In phase I, 25 of 50 4-5-week-old specific-pathogen-free (SPF) pigs were exposed to NEB-1 PRRSV (day 0). Seven days after virus inoculation, 8 groups received 1 of 4 bacterial pathogens: Haemophilus parasuis, Streptococcus suis, Salmonella cholerasuis, and Pasteurella multocida. The ability of NEB-1 PRRSV to produce clinical disease, viremia, neutralizing antibody, gross and microscopic lesions and to potentiate bacterial pathogens was assessed. Response to NEB-1 PRRSV was similar among inoculated pigs; prolonged hyperthermia, lethargy, mild to moderate dyspnea, and cutaneous erythema were consistent clinical signs. No clinical differences were observed in groups after bacterial challenge. Virus was isolated from serum at weekly intervals through the end of the study, and all PRRSV-inoculated pigs had seroconverted by study termination. Two of 5 pigs died in non-PRRSV-inoculated groups challenged with H. parasuis and Streptococcus suis. Mortality in PRRSV-infected pigs was limited to 1 of 5 pigs from the Salmonella cholerasuis-challenged group. Gross lesions were seen in pigs dying after inoculation in H. parasuis- and Streptococcus suis-inoculated groups, in Salmonella cholerasuis- and P. multocida-challenged pigs, and in 1 non-PRRSV-inoculated control pig. Microscopic lesions consisted of mild to moderate proliferative interstitial pneumonia, nonsuppurative myocarditis, lymphoid hyperplasia, and nonsuppurative encephalitis in PRRSV-inoculated pigs. Findings in phase I indicated that NEB-1 PRRSV does not potentiate bacterial disease while inducing consistent clinical signs, viremia, seroconversion, and microscopic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Incarceration of the jejunum in the epiploic foramen of a four month old foal

A 4-month Arabian filly presented for abdominal pain of 30 hours duration was found to have tachycardia, tachypnea, congested mucous membranes and gross abdominal distension. Further examination disclosed gastric reflux and small intestinal distension. Dehydration, prerenal azotemia, electrolyte abnormalities and metabolic alkalemia were observed. There was a progressive nonresponse to analgesic medication and deterioration in the foal's physiologic condition consistent with a small intestinal strangulating obstruction. Surgical exploration was declined. Necropsy examination revealed incarceration of the mid-jejunum in the epiploic foramen with proximal jejunal distension. This case is remarkable as the first report of entrapment of the jejunum in the epiploic foramen of a young foal.