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Biomedical subjects

C M van der Horst

Publications and source records attributed to C M van der Horst.

At least 19 recordsLinked to original sources
PubMed2006

Topical negative pressure therapy in wounds after cardiothoracic surgery: successful experience supported by literature.

BACKGROUND: Patients undergoing cardiothoracic surgery are at substantial risk of developing surgical site infections (SSI). SSI is not only associated with an increased morbidity but also with high mortality. Topical negative pressure therapy (TNP) is a promising method for treating surgical site defects (SSD). In recent years, we have gained a wide experience with TNP in a great variety of SSD. METHODS: We completed a prospective follow-up report of all patients treated with TNP after cardiothoracic surgery at the Academic Medical Centre Amsterdam, a university hospital. A review of the current evidence for TNP in cardiothoracic surgery is presented. RESULTS: Between August 2000 and March 2005, TNP was used in 105 patients in 113 SSD. As we gained more experience, we saw a decline in hospital stay ( P < 0.0001) and duration of TNP therapy. Surgical closure was performed in 62 % of patients using simple surgical (reconstructive) techniques. Therapy-related complications were rare (n = 1). CONCLUSION: Based on clinical findings and supported by the research presented, the treatment modality of choice for SSD after cardiothoracic surgery is TNP.

Aged↗
PubMed2001

Use of magnetic resonance imaging for the evaluation of vascular malformations of the lower extremity.

Vascular malformations are anatomically subdivided according to the predominant channel anomaly into either capillary, arterial, venous, lymphatic, or combinations. They can be further subdivided into high- or low-flow malformations. Any lesion that has an arterial component is considered a high-flow malformation. Once the diagnosis of a vascular malformation is made, it is of paramount importance to define not only the flow characteristics but also the full range of extension, because the prognosis and appropriate treatment vary substantially for each type of anomaly. The two most useful noninvasive imaging techniques for assessing vascular malformations are magnetic resonance imaging (MRI) and ultrasonography. The aim of this review is to give surgeons involved in treating patients with vascular malformations an opportunity to gain some background on MRI scans when assessing vascular malformations. Although MRI is a powerful modality for assessing vascular malformations, we will also discuss some of the limitations of MRI. We further suggest a diagnostic flow chart developed on the basis of MRI features designed to help determine the composition of a vascular birthmark when intervention is anticipated.

Blood Vessels↗
PubMed2001

Magnetic resonance imaging findings of vascular malformations of the lower extremity.

Vascular malformations are congenital lesions resulting from a defect during embryogenesis. Magnetic resonance imaging (MRI) is a very effective method for demonstrating detailed information regarding involved structures, extent, and flow characteristics of vascular malformations. In previous MRI studies, most of the emphasis is laid on the difference between high- and low-flow lesions, whereas little detailed information is available about the extent of local tissue involvement. These additional characteristics may influence the approach in treating these malformations and improve understanding of the pathogenesis. We retrospectively reviewed MRI scans of 40 patients with vascular malformations of the lower extremity. Thirty-four patients had low-flow lesions, and six had high-flow lesions. Of the low-flow lesions, 23 patients (67.6 percent) had muscle infiltration, with four of the six high-flow lesions having muscle infiltration. Nine of the 11 male patients (81.8 percent) with low-flow lesions had associated muscle infiltration, in comparison with 14 of the 23 female patients (60.9 percent) with low-flow lesions (p = 0.206). Eighty percent of the vascular malformations located on the thigh with muscle involvement had involvement of the anterior muscle group, whereas 86.6 percent of the patients with a vascular malformation located on the leg and with associated muscle involvement had at least the posterior muscle group involved (p = 0.0049). Ten patients (25 percent) of the whole group had bone infiltration. Low-flow lesions often had multifocal lesions (20.6 percent), whereas associated muscle atrophy was visible in 10 low-flow lesions and in two high-flow lesions. In low-flow lesions with muscle infiltration (n = 23), 43 percent (n = 10) had associated surrounding muscle atrophy (p = 0.009). Hypertrophy of the subcutaneous tissue was visible in 11 low-flow patients (32.4 percent). The high amount of muscle and bone involvement in vascular malformations of the lower extremity is emphasized with this study. Of particular interest was the difference in affected muscle groups. The angiosome concept is used to explain this preponderance, and we feel the angiosome concept could also be used when assessing possible intervention. The surrounding muscle atrophy and multifocal nature of these anomalies are further important considerations when assessing the possibility of intervention.

Adolescent↗
PubMed2001

Histologic evaluation of skin damage after overlapping and nonoverlapping flashlamp pumped pulsed dye laser pulses: A study on normal human skin as a model for port wine stains.

BACKGROUND AND OBJECTIVE: In the treatment of port wine stains (PWS) with the flashlamp pumped pulsed dye laser (FPPDL), no consensus exists about overlapping of pulses. The advantage of overlapping pulses is homogeneous lightening of the PWS; the risk is redundant tissue damage. The aim of this study was to determine the histopathologic effect on human skin of pulsed dye laser pulses with various degrees of overlap, with normal human skin as a model for PWS. STUDY DESIGN/MATERIALS AND METHODS: Eighteen healthy white volunteers were irradiated with pulsed dye laser pulses with increasing radiant exposure and with different degrees of overlap. Biopsy samples were taken and histologically analysed. RESULTS: Overlapping of pulses on normal human skin enhances depth of vascular damage with approximately 30%. Adjacent pulses also show this effect. We found no histologic signs of serious damage to epidermis or dermal connective tissue by using radiant exposure levels of 6-8 J/cm(2), regardless of pulse application. CONCLUSIONS: Reasoning that the mechanism of tissue injury is comparable for normal and PWS skin, we conclude that it is safe to treat PWS with overlapping FPPDL pulses to achieve homogeneous lightening.

Abdomen↗
PubMed2001

Introduction of the flash-lamp pulsed-dye laser treatment of facial port-wine stains in childhood: A case of health care technology assessment.

BACKGROUND AND OBJECTIVE: Lasers have been used in the treatment of port-wine stains (PWS) for more than 30 years. With the introduction of the flash-lamp pulsed-dye laser (FPDL) it was assumed that infants could be treated safely, effectively, and probably more efficiently. Nowadays, FPDL treatment is an established form of treatment of PWS in childhood. STUDY DESIGN/MATERIALS AND METHODS: On the basis of the iterative Health Care Technology Assessment (HCTA) loop, we examined whether sufficient evidence from evaluations has been present to support the introduction of FPDL treatment for facial PWS at an early age. Such an assessment requires an interdisciplinary approach focusing on aspects of safety, efficacy, effectiveness, quality of life, costs, and the ethical issues of treatment. RESULTS: Assessment of the FPDL in PWS treatment of children did not follow the model of medical innovation and evaluation. Most assessments have been focused on laser applications that were already in clinical use. Efficacy and effectiveness of laser treatment have been the major concern in most assessments. Only a few studies have looked at costs and ethical aspects of treating children. CONCLUSIONS: The introduction and diffusion of the use of the FPDL in the treatment of PWS in childhood were uncontrolled, and the field was not prepared to use this technique properly. We believe that this nonadherence to the iterative HCTA model reflects the gradual way by which innovations find their way into clinical practice.

Adolescent↗
PubMed2001

Prediction of portwine stain clearance and required number of flashlamp pumped pulsed dye laser treatments.

BACKGROUND AND OBJECTIVE: Portwine stain (PWS) response to flashlamp pumped pulsed dye laser (FPPDL) treatment is variable and unpredictable. Our aim was to develop a model to predict treatment outcome and the required number of treatments. STUDY DESIGN/MATERIALS AND METHODS: We hypothesized that PWS clearance decreases exponentially with the number of treatments, as a consequence of the exponential decrease of laser light fluence in human skin. Of 70 patients with a PWS in the head/neck area, the color difference between normal skin and PWS was measured with a chromameter, prior to, and at several stages during FPPDL treatment. Through the obtained values of each of the four color parameters, DeltaL*, Deltaa*, Deltab*, and DeltaE, mono-exponentially decreasing functions were fitted. RESULTS: All four color parameters showed decreasing exponential functions, with decay rates that were not significantly different, and a mean R(2) of 0.6, indicating a reliable fit-quality. CONCLUSIONS: Our model suggests that individual prediction of treatment outcome and the required number of treatments is possible in an early stage of FPPDL treatment of PWS, in theory already after one single laser treatment.

Adolescent↗
PubMed1999

Use of cerebrospinal fluid shunt for the management of elevated intracranial pressure in a patient with active AIDS-related cryptococcal meningitis.

Persistently elevated intracranial pressure (ICP) is one of the most accurate predictors of a poor prognosis in patients with AIDS-related cryptococcal meningitis. We present a severe case of persistent cryptococcal meningitis in a patient with advanced AIDS, complicated by elevation of ICP. A ventriculoperitoneal shunt was placed that successfully lowered the ICP and alleviated the associated symptoms. The elevated ICP secondary to AIDS-related cryptococcal meningitis should be treated aggressively. Despite the risk of shunt complications, cerebrospinal fluid shunts can be considered in these patients if they do not respond to other treatment.

AIDS-Related Opportunistic Infections↗
PubMed1998

Effect of the timing of treatment of port-wine stains with the flash-lamp-pumped pulsed-dye laser.

BACKGROUND: Port-wine stains can be treated with a flash-lamp-pumped pulsed-dye laser, but it is uncertain whether this treatment is more effective if administered early in life, when the skin is thinner and the lesion is smaller. METHODS: We prospectively studied 100 patients with a previously untreated port-wine stain of the head or neck. They were treated with the flash-lamp-pumped pulsed-dye laser and divided into four age groups (0 to 5, 6 to 11, 12 to 17, and 18 to 31 years). The outcome measure was lightening of the port-wine stain (reduction in the difference in color between the skin with the stain and contralateral healthy skin) as measured with a colorimeter after an average of five treatments (range, three to seven) of the entire lesion. RESULTS: Of the 100 patients, 11 could not be included in the analysis because they had received fewer than three or more than seven treatments, had an erroneous base-line color measurement, or were lost to follow-up. The sizes, locations, and colors of the port-wine stains were similar among the groups. When all 89 patients were analyzed together, the average reduction in the difference in color between the skin with the port-wine stain and contralateral healthy skin was 40 percent. The differences between age groups in the average reduction in color differences were not significant (P= 0.26). By the end of the study, only 7 of 89 patients had completed laser therapy, and in no case was clearance complete. Treatment was discontinued in all seven because the last three treatments did not lead to further lightening. CONCLUSIONS: We found no evidence that treatment of port-wine stains with the flash-lamp-pumped pulsed-dye laser in early childhood is more effective than treatment at a later age.

Adolescent↗
PubMed1998

Assessment of clinical outcome after flashlamp pumped pulsed dye laser treatment of portwine stains: a comprehensive questionnaire.

A generally accepted method to assess the clinical outcome of laser treatment of portwine stains is not available. This paper describes the development and evaluation of a comprehensive questionnaire for the assessment of the following portwine stain characteristics: color (hue and lightness), sharpness of boundary, pigmentation, size, shape, skin surface-structure, and hypertrophy of underlying tissue. The questionnaire was applied to photographs of 70 patients with previously untreated portwine stains in the head/neck area. Photographs were taken before treatment and after five treatments of the entire portwine stain with a flashlamp pumped pulsed dye laser. Each photograph was evaluated separately by a panel of five professionals: the treating physician, two plastic surgeons, a dermatologist, and a clinical photographer. Treatment results were assessed by comparing ratings before and after treatment. Agreement among raters was acceptable for all portwine stain characteristics, as was shown by weighted kappa analysis. The reliability of the answers was further improved by taking the average rating of the five panel members. The scores thus obtained were very reliable, with Cronbach alpha coefficients of 0.8 on average. After five treatments of the entire portwine stain, the most considerable changes were measured in the ratings for color (lightening of the stain by 33 percent), boundary (sharpness reduced by 38 percent), and size (13-percent decrease). Using the questionnaire can be helpful in the design of comparative clinical trials on portwine stain treatment and may facilitate comparison of treatment results between different treatment centers and/or different lasers.

Adolescent↗
PubMed1998

Characterization of portwine stain disfigurement.

Portwine stain disfigurement is caused by several factors. To what extent and in which proportion these factors influence the overall perceived disfigurement is incompletely understood. In this study, the contribution of seven portwine stain characteristics to overall portwine stain disfigurement was assessed. Color slides were taken from 90 patients with untreated portwine stains in the head/neck area. From these slides, overall portwine stain disfigurement was judged by a panel of 16 lay persons. The reliability of the average ratings of this panel was established with weighted kappa analysis (kappa = 0.51) and by calculating the Cronbach alpha coefficient (0.99). Using a previously tested multi-item questionnaire, the following portwine stain characteristics were rated quantitatively by a panel of five professionals: color, patchiness, boundary, size, shape, surface structure, and hypertrophy of the underlying tissue. By means of multiple linear regression analysis, the ratings for overall portwine stain disfigurement (panel of lay persons) were compared with the ratings for the individual portwine stain characteristics (panel of professionals). From the results of this analysis, the percentual contribution of each of the characteristics to overall portwine stain disfigurement was calculated. Size turned out to be the most important portwine stain characteristic, being responsible for almost half of the overall disfigurement. Color and boundary are the next two most important characteristics, contributing 18.7 and 12.4 percent, respectively. The other four characteristics together account for 10 percent. In our model, 13 percent of overall portwine stain disfigurement remains unexplained. We expect patient features to account for this. We feel that these results may have consequences for laser treatment of portwine stains. Reducing the size and fading out the boundary of the stain probably reduce overall portwine stain disfigurement more effectively than primarily trying to lighten the often persistent center of the stain.

Adolescent↗
PubMed1997

Treatment of cryptococcal meningitis associated with the acquired immunodeficiency syndrome. National Institute of Allergy and Infectious Diseases Mycoses Study Group and AIDS Clinical Trials Group.

BACKGROUND: Treatment with low-dose amphotericin B (0.4 mg per kilogram of body weight per day) or oral azole therapy in patients with the acquired immunodeficiency syndrome (AIDS) and cryptococcal meningitis has been associated with high mortality and low rates of cerebrospinal fluid sterilization. METHODS: In a double-blind multicenter trial we randomly assigned patients with a first episode of AIDS-associated cryptococcal meningitis to treatment with higher-dose amphotericin B (0.7 mg per kilogram per day) with or without flucytosine (100 mg per kilogram per day) for two weeks (step one), followed by eight weeks of treatment with itraconazole (400 mg per day) or fluconazole (400 mg per day) (step two). Treatment was considered successful if cerebrospinal fluid cultures were negative at 2 and 10 weeks or if the patient was clinically stable at 2 weeks and asymptomatic at 10 weeks. RESULTS: At two weeks, the cerebrospinal fluid cultures were negative in 60 percent of the 202 patients receiving amphotericin B plus flucytosine and in 51 percent of the 179 receiving amphotericin B alone (P=0.06). Elevated intracranial pressure was associated with death in 13 of 14 patients during step one. The clinical outcome did not differ significantly between the two groups. Seventy-two percent of the 151 fluconazole recipients and 60 percent of the 155 itraconazole recipients had negative cultures at 10 weeks (95 percent confidence interval for the difference in percentages, -100 to 21). The proportion of patients who had clinical responses was similar with fluconazole (68 percent) and itraconazole (70 percent). Overall mortality was 5.5 percent in the first two weeks and 3.9 percent in the next eight weeks, with no significant difference between the groups. In a multivariate analysis, the addition of flucytosine during the initial two weeks and treatment with fluconazole for the next eight weeks were independently associated with cerebrospinal fluid sterilization. CONCLUSIONS: For the initial treatment of AIDS-associated cryptococcal meningitis, the use of higher-dose amphotericin B plus flucytosine is associated with an increased rate of cerebrospinal fluid sterilization and decreased mortality at two weeks, as compared with regimens used in previous studies. Although consolidation therapy with fluconazole is associated with a higher rate of cerebrospinal fluid sterilization, itraconazole may be a suitable alternative for patients unable to take fluconazole.

AIDS-Related Opportunistic Infections↗
PubMed1997

Psychosocial adjustment of children and adults with port wine stains.

OBJECTIVES: To assess the impact of a facial port wine stain (PWS) on behavioural problems in children and on health related quality of life in adults applying for laser treatment. DESIGN: A survey by questionnaire of patients with PWS not previously treated. OUTCOME MEASURES: Two standard general instruments and a more specific PWS questionnaire were used. Adolescents and adults (13-31 years) received a short version of the RAND Health Insurance Questionnaire from the Medical Outcome Study (MOS-24). Children's (4-12 years) parents received the Child Behaviour Checklist (CBCL). A specific PWS questionnaire was sent to both age groups. ANALYSIS: The results of the MOS-24 were compared with those of a reference population without chronic illness. Observed behaviour in children was compared with data from a Dutch reference group, from children with constipation and from another group of children with a PWS. RESULTS: 41 MOS-24 and 41 CBCL were returned (91% and 95% response rates, respectively). Adolescents and adults reported little effect on role and social functioning, but showed low scores for mental health, self-perceived health and vitality/health. Children's parents reported no clinically significant problem behaviour (T-score > 70). Adults experienced more negative psychosocial consequences of having a PWS than children (specific PWS questionnaire). CONCLUSIONS: Children with PWS do not show significant problem behaviour. Adolescents and adults reported less vitality/energy than was expected in this age group. Adolescents and adults showed statistically significant negative consequences of their PWS in social contacts compared to children (P < or = 0.01, Mann-Whitney).

Adolescent↗
PubMed1997

Severe life stress as a predictor of early disease progression in HIV infection.

OBJECTIVE: Although there is evidence that stress is associated with alterations in immunity, the role of emotional factors in the onset and course of immune-based diseases such as cancer and AIDS has not been established. This prospective study was designed to test the hypothesis that stressful life events accelerate the course of HIV disease. METHOD: Ninety-three HIV-positive homosexual men who were without clinical symptoms at the time of entry into the study were studied for up to 42 months. Subjects received comprehensive medical, neurological, neuropsychological, and psychiatric assessments every 6 months, including assessment of stressful life events during the preceding 6-month interval. Several statistical approaches were used to assess the relation between stress and disease progression. RESULTS: The time of the first disease progression was analyzed with a proportional hazard survival method, which demonstrated that the more severe the life stress experienced, the greater the risk of early HIV disease progression. Specifically, for every one severe stress per 6-month study interval, the risk of early disease progression was doubled. Among a subset of 66 subjects who had been in the study for at least 24 months, logistic regression analyses showed that higher severe life stress increased the odds of developing HIV disease progression nearly fourfold. the degree of disease progression was also predicted by severe life stress when a proportional odds logistic regression model was used for analysis. CONCLUSIONS: This report presents the first evidence from a prospective research study that severe life event stress is associated with an increased rate of early HIV disease progression.

Adult↗
PubMed1996

Disposition of didanosine in HIV-seropositive patients with normal renal function or chronic renal failure: influence of hemodialysis and continuous ambulatory peritoneal dialysis.

OBJECTIVE: To evaluate the pharmacokinetics of didanosine in patients with normal kidney function or chronic kidney failure. METHODS: Three groups of patients with human immunodeficiency virus (HIV) infection were studied: group I, six men with normal kidney function (creatinine clearance > 90 ml/min/1.73 m2); group II, six men with chronic renal failure maintained on continuous ambulatory peritoneal dialysis (CAPD); and group III, four men and two women with chronic renal failure receiving hemodialysis three times a week. A 300 mg dose of didanosine was administered orally and intravenously according to a two-period randomized crossover design. Patients in group III were studied between hemodialysis sessions during the crossover periods. In addition, patients in group III were studied in a third period after administration of a 300 mg oral dose of didanosine 4 hours before hemodialysis. RESULTS: After intravenous administration in group I, the mean (+/-SD) total clearance (CLT) was 13.0 +/- 1.6 ml/min/kg and the elimination half-life (t 1/2) was 1.56 +/- 0.43 hour. In groups II and III, the CLT decreased significantly to 3.4 +/- 1.2 and 3.2 +/- 1.2 ml/min/kg, respectively, whereas the t1/2 increased to 3.60 +/- 0.82 hours and 3.11 +/- 0.88 hours, respectively. The absolute bioavailability of didanosine in groups I, II, and III was 42% +/- 12%, 52% +/- 6%, and 38% +/- 11%, respectively, and did not differ significantly. CAPD had little effect on the removal of didanosine, whereas approximately 30% of the drug present in the body at the start of dialysis was eliminated by an average 3-hour dialysis session. CONCLUSION: The clearance of didanosine is impaired in patients with chronic renal failure. To compensate, the dose and schedule of administration should be adjusted. It is recommended that one-fourth of the total daily dose of didanosine be administered once a day in this patient population.

Administration, Oral↗
PubMed1995

Transient high titers of HIV-1 in plasma and progression of disease.

Periodic quantitative HIV-1 plasma cultures were performed on 28 seropositive individuals who had CD4 cells < or = 300/mm3 and who were enrolled in three clinical trials testing the efficacy of didanosine versus zidovudine monotherapy. Most plasma cultures were negative or of low titer (1-100 tissue culture infective dose/ml of plasma), but there were 14 instances of high-titered plasma viremia (> or = 1,000 tissue culture infective dose/ml of plasma) seen in 11 individuals. These peaks in plasma culture titers were significantly associated either with rapidly decreasing CD4 cell numbers or with CD4 cells already < 50/mm3. In addition, patients who experienced these episodes of high-titered plasma viremia were more apt to have clinical complaints of fever, rash, flu-like illness, and/or opportunistic infection and also the syncytium-inducing HIV-1 phenotype and progression of disease.

AIDS-Related Opportunistic Infections↗
PubMed1995

Pharmacokinetics and bioavailability of zidovudine and its glucuronidated metabolite in patients with human immunodeficiency virus infection and hepatic disease (AIDS Clinical Trials Group protocol 062).

The pharmacokinetics of zidovudine (ZDV) are established in patients with various stages of human immunodeficiency virus (HIV) disease. This study was conducted to determine the pharmacokinetic parameters of ZDV in patients with asymptomatic HIV infection and liver disease. HIV-infected volunteers with normal renal function were stratified according to the severity of liver disease (seven of eight were classified as mild). Each subject received a single intravenous dose of ZDV (120 mg) on the first day, followed by a single oral dose of ZDV (200 mg) on the second day. Blood samples were obtained over a 8-h collection interval, and concentrations of ZDV and its glucuronidated metabolite (GZDV) were determined by high-performance liquid chromatography. The following pharmacokinetic parameters were obtained after oral administration of ZDV to HIV-infected patients with mild hepatic disease; these values were compared with previously reported data in healthy volunteers. The area under the curve (AUC) (1,670 +/- 192 ng.h/ml), maximum concentration of drug in serum (1,751 +/- 180 ng/ml), and half-life (2.04 +/- 0.38 h) of ZDV were increased, while the apparent oral clearance (1.57 +/- 0.31 liter/h/kg of body weight) was decreased; AUC (7,685 +/- 1,222 ng.h/ml) and maximum concentration of drug in serum (5,220 +/- 1,350 ng/ml) of GZDV and the AUC ratio of GZDV to ZDV (2.79 +/- 0.43) after oral administration were decreased. ZDV absolute bioavailability was 0.75 +/- 0.15 in HIV-infected patients with hepatic disease. Although the ZDV apparent oral clearance was not impaired as significantly as in patients with biopsy-proven cirrhosis, our results suggest that ZDV, could accumulate in HIV-infected patients with mild hepatic disease because of impaired formation of GZDV. Patients with mild hepatic disease may require dosage adjustment to avoid accumulation of ZDV after extended therapy.

Administration, Oral↗