18 results on '"Reichmuth K"'
Search Results
2. A review of the use of high-flow nasal cannula oxygen therapy in hospitalised children at a regional hospital in the Cape Town Metro, South Africa.
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Hoffman, E., Reichmuth, K. L., and Cooke, M. L.
- Published
- 2019
- Full Text
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3. E015 Parental communication-training after early diagnosis of hearing-impairment by UNHS – The concept
- Author
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Reichmuth, K., Embacher, A., Glanemann, R., Matulat, P., and Zehnhoff-Dinnesen, A. am
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- 2011
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4. E016 Parental communication-training after early diagnosis of hearing-impairment by UNHS – First results
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Glanemann, R., Reichmuth, K., Matulat, P., and Zehnhoff-Dinnesen, A. am
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- 2011
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5. E014 PC-BASED Word-Training after pediatric cochlear implantation
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Glanemann, R., Reichmuth, K., Fiori, A., Zehnhoff-Dinnesen, A. am, and Dobel, C.
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- 2011
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6. Older adults with ci: communication skills, social participation and quality of life.
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Hofmann, R., Reichmuth, K., Brinkheetker, S., and am Zehnhoff-Dinnesen, A.
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CONFERENCES & conventions , *COCHLEAR implants , *COMMUNICATIVE competence , *QUALITY of life , *SOCIAL participation - Abstract
Objectives: The success of cochlear implantation in postlingually deafened adults is usually measured by puretone and speech audiometry. However, the WHO states in the ICF that rehabilitation should also be assessed according to individual communication skills, social participation and quality of life. We developed and implemented a questionnaire that focuses on everyday communication and allows comparison between people with normal and impaired hearing. A parallel version for assessment of the CI-users' communication by their significant other was also developed. Additionally, we assessed social participation and quality of life of CI-users before implantation and with 4 months CI experience Sources and methods: In a prospective pilot study, five post-lingually and progressively deafened participants (55-80 yrs) and their significant others answered questionnaires concerning communication behaviour (questionnaire developed by the authors), social and emotional handicap (HHIA, HHIE, HII-SOP) [1-3], and quality of life (AQoL-6D) [4] at two timepoints: before implantation and with 4 months CI experience. Hearing ability was measured using pure-tone and speech audiometry and the SSQ [5]. Five matched normal-hearing participants served as controls. Results: Participants with 4 months CI experience reported fewer misunderstandings, higher communicative success and less communicative effort than before implantation, though they did not reach the level of normal-hearing controls on these measures. CI users still often pretend that they have understood spoken communication and are still dependent on their significant other. They wish for further communicative success and greater independence. Conclusion: Cochlear implantation alone does not lead to normal communication behaviour and social participation. These issues and the role of the significant other should also be focused on in rehabilitation alongside auditory training. Apart from the AQoL-6D the questionnaires used in this study proved to be suitable instruments for documenting the course of rehabilitation. [ABSTRACT FROM AUTHOR]
- Published
- 2018
7. Dialysis for paediatric acute kidney injury in Cape Town, South Africa.
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McCulloch MI, Luyckx VA, Morrow B, Nourse P, Coetzee A, Reddy D, Du Buisson C, Buckley J, Webber I, Numanoglu A, Sinclair G, Nelson C, Salie S, Reichmuth K, and Argent AC
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- Humans, South Africa epidemiology, Retrospective Studies, Child, Preschool, Male, Infant, Female, Child, Adolescent, Renal Dialysis adverse effects, Renal Dialysis methods, Infant, Newborn, Treatment Outcome, Acute Kidney Injury therapy, Acute Kidney Injury mortality, Acute Kidney Injury epidemiology, Peritoneal Dialysis adverse effects, Peritoneal Dialysis methods
- Abstract
Background: Dialysis is lifesaving for acute kidney injury (AKI), but access is poor in less resourced settings. A "peritoneal dialysis (PD) first" policy for paediatric AKI is more feasible than haemodialysis in low-resource settings., Methods: Retrospective review of modalities and outcomes of children dialysed acutely at Red Cross War Memorial Children's Hospital between 1998 and 2020., Results: Of the 593 children with AKI who received dialysis, 463 (78.1%) received PD first. Median age was 9.0 (range 0.03-219.3; IQR 13.0-69.6) months; 57.6% were < 1 year old. Weights ranged from 0.9 to 2.0 kg (median 7.0 kg, IQR 3.0-16.0 kg); 38.6% were < 5 kg. PD was used more in younger children compared to extracorporeal dialysis (ECD), with median ages 6.4 (IQR 0.9-30.4) vs. 73.9 (IQR 17.5-113.9) months, respectively (p = 0.001). PD was performed with Seldinger soft catheters (n = 480/578, 83%), predominantly inserted by paediatricians at the bedside (n = 412/490, 84.1%). Complications occurred in 127/560 (22.7%) children receiving PD. Overall, 314/542 (57.8%) children survived. Survival was significantly lower in neonates (< 1 month old, 47.5%) and infants (1-12 months old, 49.2%) compared with older children (> 1 year old, 70.4%, p < 0.0001). Survival was superior in the ECD (75.4%) than in the PD group (55.6%, p = 0.002)., Conclusions: "PD First for Paediatric AKI" is a valuable therapeutic approach for children with AKI. It is feasible in low-resourced settings where bedside PD catheter insertion can be safely taught and is an acceptable dialysis modality, especially in settings where children with AKI would otherwise not survive., (© 2024. The Author(s).)
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- 2024
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8. Aetiology of pleural effusions in children living in a high TB endemic setting.
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Wordui S, Masu A, Golden L, Chaya S, Reichmuth K, Visagie A, Ayuk A, Owusu SK, Marangu D, Affendi N, Lakhan A, Gray D, Vanker A, Zar HJ, and Zampoli M
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- Humans, Male, Female, Child, Preschool, Child, Cross-Sectional Studies, Infant, South Africa epidemiology, Tuberculosis diagnosis, Tuberculosis complications, Tertiary Care Centers, Endemic Diseases, Pleural Effusion microbiology, Pleural Effusion etiology, Pleural Effusion diagnosis, Polymerase Chain Reaction
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BACKGROUND Confirming the aetiology of pleural effusion in children may be difficult in TB-endemic settings. We investigated the role of polymerase chain reaction (PCR) and routine biochemical tests in discriminating pleural effusion caused by bacteria from other aetiologies.METHODS This is a cross-sectional post-hoc analysis among children with pleural effusion in a tertiary hospital in South Africa, incorporating new data from PCR testing of stored pleural fluid. Aetiological classification was defined by microbiological confirmation.RESULTS Ninety-one children were enrolled; the median age 31 months (IQR 12-102). The aetiology of pleural effusion was 40% (36/91) bacteria, 11% (10/91) TB, 3% (3/91) viruses, 11% (10/91) polymicrobial and 35% (32/91) had no pathogen identified. The most common pathogen was Staphylococcus aureus (27/91, 30%) with similar yields on culture and PCR, followed by Streptococcus pneumoniae (12/91, 13%), detected more commonly by PCR. PCR reduced the number of children with unconfirmed aetiologies from 48 to 32. Characteristics of children with no pathogen most resembled those with TB. Pleural fluid lactate dehydrogenase ≥1,716 U/L best discriminated bacterial pleural effusion from other aetiologies (sensitivity of 86%; specificity 95%). .CONCLUSION PCR improved detection of pathogens and reduced number of children with unconfirmed aetiologies in presumed exudative pleural effusion.- Published
- 2024
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9. Paediatric anaphylaxis in South Africa.
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Chippendale SE, Reichmuth K, Worm M, and Levin M
- Abstract
Introduction: Anaphylaxis is a severe, life-threatening generalized hypersensitivity reaction. While guidelines to reduce the morbidity, risk, and mortality of anaphylaxis are widely available, adherence to these is often suboptimal. We aimed to audit paediatric anaphylaxis at a South African tertiary allergy referral centre, comparing our data to those of the large Network of Severe Allergic Reactions (NORA) registry., Methods: Children treated for severe allergic reactions between January 2014 and August 2016 were identified for screening using ICD-10 coding of all admissions and discharges, pharmacy records of adrenaline autoinjector dispensing, and additional referrals from the allergy department to the study. Screened participants not meeting the inclusion criteria after preliminary questioning and/or folder review were excluded. Data were collected via a standardized questionnaire using direct interviews, and captured on a local web-based registry., Results: Of the 156 episodes analysed, >40% were graded as severe and nearly two-thirds of patients were seen for a recurrent episode. Males, younger children, and individuals of mixed-race ethnicity were more frequently affected. Skin and mucosa were most commonly involved, followed by respiratory and gastrointestinal involvement; cardiovascular and other systemic involvement occurred infrequently. Specific IgE assay was the most frequently requested test. Food-related triggers (peanut, hen's egg, fish, cashew nuts and cows' milk) predominated and decreased with age. Anaphylaxis was strongly correlated with atopic conditions. While prophylactic measures were almost universally instituted, adrenaline was rarely used, by both lay persons and healthcare professionals. Hospital admissions were infrequent, and no deaths were recorded., Conclusion: Management of anaphylaxis can be improved. Specifically, the use of adrenaline prior to hospital arrival remains suboptimal. Ongoing education and training of patients, parents, teachers, and healthcare workers is identified as an area requiring intensification., Competing Interests: None to declare., (© 2022 The Authors.)
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- 2022
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10. A review of the use of high-flow nasal cannula oxygen therapy in hospitalised children at a regional hospital in the Cape Town Metro, South Africa.
- Author
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Hoffman E, Reichmuth KL, and Cooke ML
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- Adolescent, Cannula, Child, Child, Preschool, Continuous Positive Airway Pressure, Female, Hospitalization, Humans, Infant, Infant, Newborn, Male, Oxygen Inhalation Therapy instrumentation, Respiratory Tract Diseases mortality, Retrospective Studies, South Africa, Treatment Outcome, Oxygen Inhalation Therapy methods, Respiratory Tract Diseases therapy
- Abstract
Background: High-flow nasal cannula (HFNC) oxygen is a non-invasive alternative to nasal continuous positive airway pressure (CPAP) therapy for infants and children requiring respiratory support. There is a paucity of data to support its use in children, with no published data from sub-Saharan Africa., Objectives: To describe the outcomes of and adverse events related to HFNC in the first year of its use in a level 2 (L2) general paediatric ward, and to compare these outcomes with those of a historical cohort when this intervention was unavailable., Methods: This retrospective descriptive study included children aged <13 years who received HFNC in the first 12 months after its introduction (HFNC-availability group, n=66). Demographic data, clinical characteristics and outcomes (death, treatment failure, length of HFNC and HFNC-related adverse events) were assessed. A comparative description of children who required transfer to level 3 (L3) for any form of respiratory support (other than the available standard low-flow oxygen) during the 12-month period prior to HFNC availability (pre-HFNC group, n=54) was made. All analyses were performed in the paediatric wards, New Somerset Hospital, Cape Town, South Africa. Outcomes were compared using standard descriptive and comparative statistics., Results: The median age of the cohort was 5 months (interquartile range (IQR) 1.9 - 14.6). Sixteen children (13.3%) were malnourished, 10 (8.3%) were HIV-infected, and 30 (25.0%) had been born prematurely. The most common diagnoses were pneumonia, bronchiolitis and asthma. Asthma, anaemia and cardiac abnormalities were the most prevalent underlying comorbidities. Two children died in each group. All 54 children in the pre-HFNC group were transferred to L3; 38 (70.4%) needed CPAP or invasive ventilation. In the HFNC-availability period, 85 children were assessed as needing more than standard low-flow oxygen therapy: of the 19 immediately transferred to L3, 17 (89.4%) received CPAP or invasive ventilation; of the 66 who received HFNC at L2, 16 (24.2%) subsequently required transfer to L3 for CPAP or invasive ventilation. The median duration of HFNC was 46.3 hours (IQR 19.5 - 93.5) overall, and it was 12 hours (IQR 4 - 28) and 58.5 hours (IQR 39.5 - 106) for those who failed or were successfully managed on HFNC, respectively. No HFNC-related serious adverse events were recorded., Conclusions: HFNC is a safe, effective, feasible option for non-invasive ventilation of children with respiratory illnesses in a resource-limited L2 setting. A greater proportion of children with lower respiratory tract infections in the HFNC-availability group than in the pre-HFNC group required support, but the intervention reduced the bed pressure on L3. Improved ways to identify HFNC failures would be beneficial.
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- 2019
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11. Osmotic induction of placental growth factor in retinal pigment epithelial cells in vitro: contribution of NFAT5 activity.
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Hollborn M, Reichmuth K, Prager P, Wiedemann P, Bringmann A, and Kohen L
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- Adult, Aged, Cell Hypoxia, Cells, Cultured, Female, Gene Expression, Humans, Macular Degeneration metabolism, Macular Degeneration pathology, Male, Middle Aged, Osmolar Concentration, Placenta Growth Factor metabolism, Retinal Pigment Epithelium pathology, Signal Transduction, Transcriptional Activation, Vascular Endothelial Growth Factor A genetics, Vascular Endothelial Growth Factor A metabolism, Epithelial Cells metabolism, Placenta Growth Factor genetics, Transcription Factors physiology
- Abstract
One risk factor of neovascular age-related macular degeneration is systemic hypertension; hypertension is mainly caused by extracellular hyperosmolarity after consumption of dietary salt. In retinal pigment epithelial (RPE) cells, high extracellular osmolarity induces vascular endothelial growth factor (VEGF)-A (Hollborn et al. in Mol Vis 21:360-377, 2015). The aim of the present study was to determine whether extracellular hyperosmolarity and chemical hypoxia trigger the expression of further VEGF family members including placental growth factor (PlGF) in human RPE cells. Hyperosmotic media were made up by addition of 100 mM NaCl or sucrose. Chemical hypoxia was induced by CoCl2. Gene expression was quantified by real-time RT-PCR, and secretion of PlGF-2 was investigated with ELISA. Nuclear factor of activated T cell 5 (NFAT5) was depleted using siRNA. Extracellular hyperosmolarity triggered expression of VEGF-A, VEGF-D, and PlGF genes, and secretion of PlGF-2. Hypoosmolarity decreased PlGF gene expression. Hypoxia induced expression of VEGF-A, VEGF-B, VEGF-D, and PlGF genes. Extracellular hyperosmolarity and hypoxia produced additive PlGF gene expression. Both hyperosmolarity and hypoxia induced expression of KDR and FLT-4 receptor genes, while hyperosmolarity caused neuropilin-2 and hypoxia neuropilin-1 gene expression. The hyperosmotic, but not the hypoxic, PlGF gene expression was in part mediated by NFAT5. The expression of PlGF in RPE cells depends on the extracellular osmolarity. The data suggest that high consumption of dietary salt may exacerbate the angiogenic response of RPE cells in the hypoxic retina via transcriptional activation of various VEGF family member genes.
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- 2016
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12. Responsive parenting intervention after identification of hearing loss by Universal Newborn Hearing Screening: the concept of the Muenster Parental Programme.
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Reichmuth K, Embacher AJ, Matulat P, Am Zehnhoff-Dinnesen A, and Glanemann R
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- Adult, Communication, Deafness congenital, Deafness therapy, Female, Germany, Hearing Loss congenital, Hearing Loss therapy, Hearing Tests, Humans, Infant, Infant, Newborn, Language Development, Male, Neonatal Screening standards, Parent-Child Relations, Program Evaluation, Audiometry standards, Deafness diagnosis, Hearing Loss diagnosis, Parenting, Parents education
- Abstract
Background: Parents of newborns with hearing loss (HL) identified by Universal Newborn Hearing Screening (UNHS) programmes wish for educational support soon after confirmation and for contact with other affected families. Besides pedaudiological care, a high level of family involvement and an early start of educational intervention are the best predictors for successful oral language development in children with HL. The implementation of UNHS has made it necessary to adapt existing intervention concepts for families of children with HL to the needs of preverbal infants. In particular, responsiveness has proven to be a crucial skill of intuitive parental behaviour in early communication between parents and their child. Since infants with HL are being fitted earlier with hearing devices, their chances of learning oral language naturally in daily communication with family members have noticeably improved., Objectives: The Muenster Parental Programme (MPP) aims at empowering parents in communicating with their preverbal child with HL and in (re-)building confidence in their own parental resources. Additionally, it supplies specific information about auditory and language development and enables exchange with other affected parents shortly after the diagnosis., Concept: The MPP is a responsive parenting intervention specific to the needs of parents of infants with HL identified by UNHS or through other indices and testing within the first 18 months of life. It is based on the communication-oriented Natural Auditory Oral Approach and trains parental responsiveness to preverbal (3-18 months) infants with HL. The MPP has been developed for groups of 4-6 families and comprises six group sessions (without infants), two single training sessions with video feedback, and two individual counselling sessions. At the age of 24-30 months, an individual refresher training session is offered to the parents for adapting their responsiveness to the current verbal level of the child via dialogic book reading. The programme also benefits parents of paediatric cochlear implant (CI) candidates preimplantation and postimplantation., Conclusions: The MPP is evidence-based (see Glanemann et al., this volume) and meets the current need for effective family-centred educational intervention after UNHS., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)
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- 2013
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13. Muenster Parental Programme empowers parents in communicating with their infant with hearing loss.
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Glanemann R, Reichmuth K, Matulat P, and Zehnhoff-Dinnesen AA
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- Adult, Cohort Studies, Deafness diagnosis, Deafness therapy, Female, Germany, Hearing Loss therapy, Humans, Infant, Male, Program Development, Program Evaluation, Prospective Studies, Severity of Illness Index, Communication, Early Intervention, Educational organization & administration, Hearing Loss diagnosis, Parent-Child Relations, Parents education
- Abstract
Objective: With the implementation of the Universal Newborn Hearing Screening (UNHS), the age of diagnosis of children with hearing loss (HL) has been steadily declining in the past years. Consequently, there is a need for early educational intervention methods that are suitable for infants at the preverbal level. To meet this need we have developed and evaluated the Muenster Parental Programme (MPP), a responsive parenting programme for parents of children with HL aged 3-18 months. It aims at enhancing the parents' communicative skills towards their child., Methods: The MPP is introduced following confirmation of a HL. Flanked by two individual counselling sessions, the programme comprises six group sessions and two single training sessions with video feedback. The focus of the programme lies in enhancing parents' responsive behaviour and in reducing inappropriate initiative behaviour. The present study involved 29 parents of 24 children aged 6.6 (mean, range: 3-12) months at the outset of the MPP. The children's degree of HL ranged from moderate to profound. Parents of children with unilateral HL and/or risk for an additional developmental delay were included. The prospective study compared parent communication skills of a trained (N = 15) versus a control group (N = 14) before and after the MPP. For this purpose, instances of responsive behaviour to the signals of the child and total time of initiative behaviour within a 4-min video-sample were measured before and after completion of the study in both groups., Results: Trained parents could enhance their responsiveness to vocal and preverbal signals of the child (Wilcoxon test, p = .002) and also their responsiveness to non-verbal signals (Wilcoxon test, p < .001). Moreover, parents reduced their inappropriate initiative behaviour (related t-test, p < .001). Pre-post comparisons in the control group were non-significant., Conclusions: The increased parental responsiveness to infants with HL is of great importance as these early behaviours underlie later acquisition of speech, language, hearing and social communication skills. The MPP constitutes the first evaluated group concept for parents of infants with HL in the German-speaking countries and equally meets the needs of parents and professionals., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)
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- 2013
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14. Antiretroviral regimens containing a single protease inhibitor increase risk of virologic failure in young HIV-infected children.
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Walters E, Reichmuth K, Dramowski A, Marais BJ, Cotton MF, and Rabie H
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- Child, Child, Preschool, Cohort Studies, Female, HIV Infections complications, Humans, Infant, Male, Retrospective Studies, Risk Assessment, Treatment Failure, Tuberculosis complications, Antitubercular Agents administration & dosage, Drug Interactions, HIV Infections drug therapy, HIV Protease Inhibitors administration & dosage, Tuberculosis drug therapy
- Abstract
Rifampin-based tuberculosis treatment can cause subtherapeutic concentrations of protease inhibitors and virologic failure in children receiving antiretroviral therapy. Among 217 children on antiretroviral therapy, tuberculosis cotreatment (in 78) was associated with virologic failure. Ritonavir-based single protease inhibitor antiretroviral therapy regimen predicted virologic failure (adjusted odds ratio 3.7, 95% confidence interval 1.5-8.9, P = 0.004) on multivariate analysis.
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- 2013
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15. Influence of cerebral blood flow on breathing stability.
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Xie A, Skatrud JB, Barczi SR, Reichmuth K, Morgan BJ, Mont S, and Dempsey JA
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- Adolescent, Adult, Blood Flow Velocity drug effects, Carbon Dioxide administration & dosage, Cardiovascular Agents pharmacology, Cerebrovascular Circulation drug effects, Female, Humans, Hypercapnia, Indomethacin pharmacology, Male, Pulmonary Ventilation drug effects, Sleep Apnea Syndromes chemically induced, Young Adult, Brain blood supply, Cerebrovascular Circulation physiology, Pulmonary Ventilation physiology, Sleep Apnea Syndromes physiopathology
- Abstract
Our previous work showed a diminished cerebral blood flow (CBF) response to changes in Pa(CO(2)) in congestive heart failure patients with central sleep apnea compared with those without apnea. Since the regulation of CBF serves to minimize oscillations in H(+) and Pco(2) at the site of the central chemoreceptors, it may play an important role in maintaining breathing stability. We hypothesized that an attenuated cerebrovascular reactivity to changes in Pa(CO(2)) would narrow the difference between the eupneic Pa(CO(2)) and the apneic threshold Pa(CO(2)) (DeltaPa(CO(2))), known as the CO(2) reserve, thereby making the subjects more susceptible to apnea. Accordingly, in seven normal subjects, we used indomethacin (Indo; 100 mg by mouth) sufficient to reduce the CBF response to CO(2) by approximately 25% below control. The CO(2) reserve was estimated during non-rapid eye movement (NREM) sleep. The apnea threshold was determined, both with and without Indo, in NREM sleep, in a random order using a ventilator in pressure support mode to gradually reduce Pa(CO(2)) until apnea occurred. results: Indo significantly reduced the CO(2) reserve required to produce apnea from 6.3 +/- 0.5 to 4.4 +/- 0.7 mmHg (P = 0.01) and increased the slope of the ventilation decrease in response to hypocapnic inhibition below eupnea (control vs. Indo: 1.06 +/- 0.10 vs. 1.61 +/- 0.27 l x min(-1) x mmHg(-1), P < 0.05). We conclude that reductions in the normal cerebral vascular response to hypocapnia will increase the susceptibility to apneas and breathing instability during sleep.
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- 2009
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16. Development and evaluation of the new module 'communication disorders' in medical education.
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Deuster D, am Zehnhoff-Dinnesen A, Schmidt CM, Matulat P, Huebner JR, Reichmuth K, Fiori A, and Knief A
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- Clinical Competence, Female, Germany, Humans, Male, Young Adult, Communication Disorders diagnosis, Curriculum, Education, Medical, Program Development, Program Evaluation methods
- Abstract
Background: Communication disorders are not taught as a self-contained topic in medical education, despite their high incidence and the similarities in the way in which they present clinically., Aims: This article describes the development of an elective subject 'Phoniatrics and Pediatric Audiology' covering five topics: hearing, language, and voice as well as psychometric tests and swallowing, with the objective of teaching a basic knowledge of the anatomy, physiology, and pathophysiology of the hearing and language system as well as symptoms, diagnostics, examination, and therapy of communication disorders. It contains theoretical background, practical exercises, and demonstrations of patient examinations., Methods: After initial modifications to the course, a statistical evaluation of the last two half-years in 2006 was performed., Results: The majority of students believe that the subject will be useful in their subsequent studies (94.2%) and medical practice (51.9%). All students affirmed that their expectations had been met by the course and they would choose it again., Conclusions: Uniting several communication disorders within a self-contained topic provides the opportunity to understand pathophysiological principles, similarities, and differences between normal and impaired function of the hearing and language system and voice production. In the authors' opinion, it is a reasonable inclusion in medical training recognizing the importance of communication in today's service society.
- Published
- 2008
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17. Influence of cerebrovascular function on the hypercapnic ventilatory response in healthy humans.
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Xie A, Skatrud JB, Morgan B, Chenuel B, Khayat R, Reichmuth K, Lin J, and Dempsey JA
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- Adaptation, Physiological, Adolescent, Adult, Blood Flow Velocity, Female, Humans, Male, Reference Values, Brain blood supply, Brain physiopathology, Carbon Dioxide metabolism, Cerebrovascular Circulation, Hypercapnia physiopathology, Respiratory Mechanics, Tidal Volume
- Abstract
An important determinant of [H(+)] in the environment of the central chemoreceptors is cerebral blood flow. Accordingly we hypothesized that a reduction of brain perfusion or a reduced cerebrovascular reactivity to CO(2) would lead to hyperventilation and an increased ventilatory responsiveness to CO(2). We used oral indomethacin to reduce the cerebrovascular reactivity to CO(2) and tested the steady-state hypercapnic ventilatory response to CO(2) in nine normal awake human subjects under normoxia and hyperoxia (50% O(2)). Ninety minutes after indomethacin ingestion, cerebral blood flow velocity (CBFV) in the middle cerebral artery decreased to 77 +/- 5% of the initial value and the average slope of CBFV response to hypercapnia was reduced to 31% of control in normoxia (1.92 versus 0.59 cm(-1) s(-1) mmHg(-1), P < 0.05) and 37% of control in hyperoxia (1.58 versus 0.59 cm(-1) s(-1) mmHg(-1), P < 0.05). Concomitantly, indomethacin administration also caused 40-60% increases in the slope of the mean ventilatory response to CO(2) in both normoxia (1.27 +/- 0.31 versus 1.76 +/- 0.37 l min(-1) mmHg(-1), P < 0.05) and hyperoxia (1.08 +/- 0.22 versus 1.79 +/- 0.37 l min(-1) mmHg(-1), P < 0.05). These correlative findings are consistent with the conclusion that cerebrovascular responsiveness to CO(2) is an important determinant of eupnoeic ventilation and of hypercapnic ventilatory responsiveness in humans, primarily via its effects at the level of the central chemoreceptors.
- Published
- 2006
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18. Mechanisms of the cerebrovascular response to apnoea in humans.
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Przybyłowski T, Bangash MF, Reichmuth K, Morgan BJ, Skatrud JB, and Dempsey JA
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- Adrenergic alpha-Agonists pharmacology, Adult, Apnea diagnostic imaging, Cerebrovascular Circulation drug effects, Female, Ganglionic Blockers pharmacology, Hemodynamics drug effects, Hemodynamics physiology, Humans, Hypercapnia physiopathology, Hyperoxia physiopathology, Hypocapnia physiopathology, Male, Middle Cerebral Artery diagnostic imaging, Middle Cerebral Artery drug effects, Middle Cerebral Artery physiology, Phenylephrine pharmacology, Respiratory Mechanics drug effects, Respiratory Mechanics physiology, Trimethaphan pharmacology, Ultrasonography, Doppler, Apnea physiopathology, Cerebrovascular Circulation physiology
- Abstract
We measured ventilation, arterial O2 saturation, end-tidal CO2 (PET,CO2), blood pressure (intra-arterial catheter or photoelectric plethysmograph), and flow velocity in the middle cerebral artery (CFV) (pulsed Doppler ultrasound) in 17 healthy awake subjects while they performed 20 s breath holds under control conditions and during ganglionic blockade (intravenous trimethaphan, 4.4 +/- 1.1 mg min-1 (mean +/- S.D.)). Under control conditions, breath holding caused increases in PET,CO2 (7 +/- 1 mmHg) and in mean arterial pressure (MAP) (15 +/- 2 mmHg). A transient hyperventilation (PET,CO2 -7 +/- 1 mmHg vs. baseline) occurred post-apnoea. CFV increased during apnoeas (by 42 +/- 3 %) and decreased below baseline (by 20 +/- 2 %) during post-apnoea hyperventilation. In the post-apnoea recovery period, CFV returned to baseline in 45 +/- 4 s. The post-apnoea decrease in CFV did not occur when hyperventilation was prevented. During ganglionic blockade, which abolished the increase in MAP, apnoea-induced increases in CFV were partially attenuated (by 26 +/- 2 %). Increases in PET,CO2 and decreases in oxyhaemoglobin saturation (Sa,O2) (by 2 +/- 1 %) during breath holds were identical in the intact and blocked conditions. Ganglionic blockade had no effect on the slope of the CFV response to hypocapnia but it reduced the CFV response to hypercapnia (by 17 +/- 5 %). We attribute this effect to abolition of the hypercapnia-induced increase in MAP. Peak increases in CFV during 20 s Mueller manoeuvres (40 +/- 3 %) were the same as control breath holds, despite a 15 mmHg initial, transient decrease in MAP. Hyperoxia also had no effect on the apnoea-induced increase in CFV (40 +/- 4 %). We conclude that apnoea-induced fluctuations in CFV were caused primarily by increases and decreases in arterial partial pressure of CO2 (Pa,CO2) and that sympathetic nervous system activity was not required for either the initiation or the maintenance of the cerebrovascular response to hyper- and hypocapnia. Increased MAP or other unknown influences of autonomic activation on the cerebral circulation played a smaller but significant role in the apnoea-induced increase in CFV; however, negative intrathoracic pressure and the small amount of oxyhaemoglobin desaturation caused by 20 s apnoea did not affect CFV.
- Published
- 2003
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