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Biomedical subjects

H Nieminen

Publications and source records attributed to H Nieminen.

At least 19 recordsLinked to original sources
PubMed2001

Airway pressure release ventilation and prone positioning in severe acute respiratory distress syndrome.

BACKGROUND: Implementation of lung protective strategy in the treatment of severe Acute Respiratory Distress Syndrome (ARDS) has been reported to be associated with improved outcome. To fulfil this approach, sedation, neuromuscular blocking agents and full mechanical ventilatory support are often used in critical failure of gas exchange. CASE REPORT: We present a patient who developed multiple organ failure, including severe ARDS, after severe skin injuries and septic shock. Ventilatory strategy consisted of lung protective approach, permissive hypercapnia and prone positioning. Airway pressure release ventilation (APRV) with the patient's superimposed spontaneous breathing was implemented and maintained, also during prone episodes. Improvement of gas exhange occurred after application of combined use of APRV and prone positioning. CONCLUSION: APRV and maintenance of patients' spontaneous ventilation is feasible during prone positioning, and this approach may have beneficial synergistic effects on gas exhange in patients with severe acute lung injury.

Adolescent↗
PubMed2000

Asymmetry of gait after free flap reconstruction of severe tibial fractures with extensive soft-tissue damage.

Gait patterns of the preferred speed were investigated on 17 patients recovering (9 months-14 years) after reconstruction of severe tibial fractures. A novel data-acquisition system was used to record the plantar pressures as well as electromyographic (EMG) activities during walking. The results indicated incomplete recovery of symmetrical gait patterns. In particular, the duration of the stance phase was shorter on the operated side (mean (SD) 701 (90) ms compared with 765 (128) ms, p < 0.001). The peak pressure points under the foot were different on bilateral comparison, the operated side being regularly higher under the lateral forefoot area. This may imply attempts to reduce the loading of the ankle joint during stance. The pressure distribution models reflected these asymmetrical patterns more specifically than the EMG activities of the lower leg muscles examined.

Adult↗
PubMed1999

Lens autofluorescence and light scatter in relation to the lens opacities classification system, LOCS III.

PURPOSE: To compare values of the human lens autofluorescence and back light scatter measurements with the improved Lens Opacities Classification System, LOCS III. METHODS: We measured autofluorescence and back light scatter of the lens from 122 smoking males aged 57 to 76 years who participated in a cancer prevention study. The retroillumination and slit-lamp photographs of the lenses were graded according to LOCS III by the Center for Ophthalmic Research in Boston. Lens fluorometry was carried out with a previously described technique using blue-green (495 nm/520 nm) autofluorescence range. Interzeag Lens Opacity Meter 701 was used for light scatter measurements. RESULTS: LOCS III nuclear opalescence and color grades were statistically significantly correlated with lens autofluorescence as well as with light scatter values. The lens transmission index of autofluorescence measurements showed the highest correlation with the nuclear color (r = -0.71; p < 0.0001) and the light scatter value with nuclear opalescence (r = 0.64; p < 0.0001). There was no correlation between autofluorescence measurements and LOCS III grades of cortical or posterior subcapsular cataract. A weak relation could be found between the grades of cortical cataract and light scatter values. CONCLUSIONS: The lens fluorometry provides a practical clinical technique to evaluate the yellow coloration and opalescence of the human lens nucleus. It may be a useful additional tool together with a subjective grading system in the follow-up of optical changes occurring in the nuclear region of the lens.

Aged↗
PubMed1999

Free flap reconstructions of 100 tibial fractures.

OBJECTIVE: Reconstructive microsurgery has been part of the treatment for severe tibial fractures for over 20 years. METHODS: In this study, we have analyzed 100 patients with 104 microvascular reconstructions to the lower leg in a 15-year period (1980-1994). Sixty-three of the reconstructions were made during the past 5 years (1990-1994), which means that microvascular reconstruction is increasing as a treatment of severe tibial fractures. RESULTS: Free flap transfer is a safe procedure: the failure rate among the patients studied was 2%, and the amputation rate was 5%. CONCLUSION: In the past 5 years, the flap survival rate and the microvascular free flap operation methods were the same as they were in the 1980s, but the methods for enhancing the fracture union or reconstructing the bone defect has changed.

Adolescent↗
PubMed1998

[Grief among the psychiatric outcare-patients].

The aim of the study is to describe the features of bereavement and the life situation among the bereaved psychiatric outcare-patients. The impact of social support on stress and adaption has been indicated in previous studies. Social support of the patients belongs to the nursing care. The possibilities of the family-centered nursing to support the relatives in bereavement will also be discussed. The sample consisted of new patients' in psychiatric outcare (N = 32). The ground of the need to the care was the dead of their relative. The information has been gathered of the care records and it has been analysed by the content analysis. Following contents have been described: The features of the bereavement and the relations to the relatives. The features of the bereavement consisted of following categories depressive behavior, anxiety, hate and fear, self-destructive behavior and feelings of guilt. Relations to the other relatives consisted of following categories: Rejected by the relatives and disappointed in the relationship. The results indicated, that the patients did not receive social support in their daily life. The family-centered nursing will allow the social support also to the relatives after the dead of the patient.

Ambulatory Care↗
PubMed1997

Influence of lens autofluorescence on retinal nerve fiber layer evaluation.

BACKGROUND: Yellow-brown coloration of the human lens increases with age and is associated with increasing lens autofluorescence. This may interfere with retinal image through scatter and absorption. PATIENTS AND METHODS: We measured the lens autofluorescence (AF) of 30 eyes of 30 healthy subjects and evaluated their retinal nerve fiber layer (RNFL) visibility from fundus photographs. These otherwise healthy eyes showed a varying degree of yellow-brown coloration of the lens. Lens fluorometry was carried out with a previously described technique using blue-green AF range (495 nm/520 nm). RNFL photographs were taken with a Canon CF-60 ZA wide angle camera with blue (495 nm) interference filter and low-sensitivity, high resolution black-and-white film. RESULTS AND CONCLUSION: Lens yellowing expressed here by means of lens autofluorescence measurements, was statistically significantly (r = -0.53, p = 0.0008) correlated with the RNFL visibility score. In stepwise regression analysis adding age to the model including only the maximum AF did not reduce the residual standard deviation statistically significantly (p = 0.1). This suggests that lens yellowing has an effect on RNFL visibility and may be an important confounding factor in clinical RNFL evaluation.

Aged↗
PubMed1997

Fluorometry of the crystalline lens for correcting blue-on-yellow perimetry results.

PURPOSE: Optical and neural sources of short wavelength sensitivity should be separated in the assessment of the results of blue-on-yellow (B/Y) perimetry. It has been shown previously that lens autofluorescence is related directly to lens yellowing and age. The aim of this study was to find out if B/Y perimetry results can be better corrected by using lens fluorometry than by age. METHODS: The authors evaluated one randomly chosen eye of 40 normal subjects and 39 age-matched patients with ocular hypertension and different stages of glaucoma. The authors obtained the mean sensitivity (MS) of the 24-2 B/Y visual fields with a Humphrey perimeter and determined the lens transmission index (LTI) from the ratio between posterior and anterior autofluorescence peaks measured with their fluorometer. A multiple regression analysis was used to evaluate the variability of the B/Y MS by age and LTI in normal subjects. RESULTS: The authors found a statistically highly significant linear correlation of B/Y MS to LTI in healthy subjects (R = 0.83; P < 0.0001). The 95% prediction interval of the normal subjects was determined. The majority of the MS values of the ocular hypertensives were inside the prediction limits, whereas approximately half of the patients (4 of 9) with early glaucoma and the majority of patients (14 of 15) with moderate and advanced glaucoma were below the prediction interval. The residual standard deviation of the B/Y MS with age alone was larger than that with LTI alone in the model (3.66 dB and 3.22 dB, respectively). CONCLUSIONS: The interindividual variation of the lens transmission properties increases with age. The reference level for correcting B/Y perimetry results can be determined more precisely using fluorometry of the lens than with age alone.

Adult↗
PubMed1996

A static shoulder model based on a time-dependent criterion for load sharing between synergistic muscles.

A static shoulder model including a novel muscular synergy principle for computing load sharing between the shoulder muscles is presented. This principle is feasible especially when analysing endurance-type activities. According to the principle, time elapsed from the start of the activity decreases the allowable muscle stress levels on the basis of the stress-endurance time curves of individual muscles. At low load levels the sum of the squared forces is minimized. At higher load levels the increase in the stress levels of individual muscles is counteracted in order to prevent fatigue. In the model the direction of the contact force in the glenohumeral joint is constrained. The stiffness of the shoulder can also be constrained to produce more muscular co-contraction in tasks with high precision demands.

Biomechanical Phenomena↗
PubMed1995

Load-sharing patterns in the shoulder during isometric flexion tasks.

Patterns of load-sharing between the shoulder muscles during isometric flexion tasks were studied by using both a biomechanical shoulder model and electromyographic (EMG) recordings of ten subjects. The effect of changes in several model parameters and shoulder stiffness constraints on the predicted load-sharing patterns were studied, while the arm position, hand load and precision requirements of the tasks were varied. The results calculated using the model were, when compared to the EMG recordings, plausible predicting a high level of synergistic contraction of muscles of the shoulder muscles during flexion tasks. The trends of the model-predicted muscle forces corresponded well to the EMG recordings. At low hand load levels the increasing of the shoulder stiffness strongly increased the muscle force levels, thus increasing also the level of synergistic contraction of muscles. At higher load levels the increase in the muscle forces was not so high, because the model predicted a high level of simultaneous contraction of muscles already at a low level of shoulder stiffness. Cluster analysis of the EMG recordings revealed large inter-individual differences in the load distribution patterns during flexion tasks. The constraint angle of the glenohumeral joint contact force direction was found to be an important model parameter affecting both the predicted forces and the maximum force production ability of the shoulder.

Adult↗
PubMed1995

Muscular synergy in the shoulder during a fatiguing static contraction.

The synergic operation of shoulder muscles during a fatiguing submaximal arm flexion task was studied using both a biomechanical 3-dimensional shoulder model and electromyographic recordings. A new optimization scheme aiming to maximize the task endurance time by constantly regulating the force output of each muscle is utilized in the model. The method can be used to simulate the muscle rotation phenomenon, which has been proposed to occur during an endurance type contraction. The model predictions on the fatigue order of the shoulder muscles were compared to results derived using the median frequencies of the electromyographic signals from nine muscles or muscle parts. In the test performed 10 men held until exhaustion a weight (4 kg) suspended on the wrist with the arm in horizontal flexion. The deltoid, infraspinatus, and supraspinatus muscles were the first to show electromyographic signs of fatigue. The times for detecting electromyographic changes in the trapezius muscle were longer than those in the muscles first showing electromyographic signs of fatigue. The biomechanical model used predicted the upper and lower infraspinatus and the anterior part of the deltoid to be the first to show signs of fatigue during the flexion task. The predictions of the biomechanical model on the order of fatigue of the nine shoulder muscles monitored also using electromyographic recordings corresponded to the electromyographic results. However, the accuracy of this comparison is limited by the fact that the electromyographic recordings did not cover all the muscles used in the model. No clear order was found for the development of electromyographic signs of muscle fatigue. RELEVANCE--:The biomechanical model and the developed optimization methods provide new tools for studying the synergic operation of shoulder muscles during fatiguing contractions. Our results will help in analysing and optimizing shoulder load in problematic functions both of work and leisure activities.

Journal Article↗
PubMed1995

Quantification of the static load component in muscle work using nonlinear filtering of surface EMG.

Prolonged static strain on the muscles of the neck-shoulder region is believed to be linked to the development of musculoskeletal problems. To quantify the static strain on the basis of EMG, the level as well as the duration of the muscle load should be analysed on temporal basis. In this paper, some methods for the temporal analysis of EMG recordings are proposed with an aim of quantifying the long-term static strain on the muscle. The use of nonlinear median prefilters for decomposing the EMG activity according both to amplitude level and duration of the activity at different levels is proposed. The prefiltering methods were also evaluated using laboratory studies. The main aim of the studies was to compare the estimation errors between EMG and force for different types of prefilters especially when the static load component was analysed. The average estimation error for sequences having a duration longer than 1 s was found to be 8% of MVC in the case of trapezius muscle and 14% of MVC in the case of biceps brachii muscle. Linear relation was found on the basis of linear least squares curve fitting to give the largest correlation coefficients between EMG and force, when the static load component was analysed.

Adult↗
PubMed1995

Free flap reconstructions of tibial fractures complicated after internal fixation.

The cases of 15 patients are presented where microvascular soft-tissue reconstructions became necessary after internal fixation of tibial fractures. Primarily, seven of the fractures were closed. Eleven fractures had originally been treated by open reduction and internal fixation using plates and screws, and four by intramedullary nailing. All of the patients suffered from postoperative complications leading to exposure of the bone or fixation material. The internal fixation material was removed and radical revision of dead and infected tissue was carried out in all cases. Soft tissue reconstruction was performed using a free microvascular muscle flap (11 latissimus dorsi, three rectus abdominis, and one gracilis). In eight cases the nonunion of the fracture indicated external fixation. The microvascular reconstruction was successful in all 15 patients. In one case the recurrence of deep infection finally indicated a below-knee amputation. In another case, chronic infection with fistulation recurred postoperatively. After a mean follow-up of 26 months the soft tissue coverage was good in all the remaining 13 cases. All the fractures united. Microvascular free muscle flap reconstruction of the leg is regarded as a reliable method for salvaging legs with large soft-tissue defects or defects in the distal leg. If after internal fixation of the tibial fracture the osteosynthesis material or fracture is exposed, reconstruction of the soft-tissue can successfully be performed by free flap transfer. By radical revision, external fixation, bone grafting, and a free flap the healing of the fracture can be achieved.

Adult↗
PubMed1993

Normalization of electromyogram in the neck-shoulder region.

Linear and curvilinear electromyogram (EMG) normalization methods were compared among ten healthy men during a simulated work cycle demanding attention and static holding of the arm ('Solitaire test'). Maximal voluntary contractions (MVC) and gradually increasing contractions up to 70% of MVC were used for normalization in different arm postures. The test contractions studied included inward and outward rotations, abduction, shoulder elevation, and flexion in different arm positions. The shoulder load moment was calculated for the flexion tests using a simple two-dimensional model. The effect of arm posture on the EMG versus shoulder load moment relationship was studied on the following muscles: supraspinatus, infraspinatus, trapezius (three parts), deltoid (two parts) and pectoralis major. All muscles participated in the MVC tests performed, and its was not possible to suggest a single recommended test for each muscle. Differences in normalized EMG median values ranging up to 30% of MVC were found between linear and curvilinear normalization methods. Short-term repeatability of normalization based on a contraction with gradually increasing force was good. Arm posture affected the relationships between shoulder load moment and EMG activity of all muscles studied. Arm posture did not, however, have a significant effect on the estimated amplitude probability distribution functions during the simulated work task. Therefore, at least for the tasks studied, the principle of normalizing in the middle position of the range of movement was deemed acceptable.

Adult↗
PubMed1993

Autofluorescence in cataractous human lens and its relationship to light scatter.

The autofluorescence profile of the lens was measured from 84 eyes of 84 patients with cortical, nuclear, posterior subcapsular, or mixed lens opacities. Measurements were performed with a fluorometer in the blue-green autofluorescence range (495 nm/520 nm). The mean maximum autofluorescence value differed in every cataract group statistically significantly from that of the age matched controls (p < or = 0.0058). The highest autofluorescence values were measured in nuclear and mixed cataract groups (p < 0.0001) with high and narrow autofluorescence profile. In cortical cataracts the curve was low and flattened and the mean maximum autofluorescence value was lower than in the control eyes (p < 0.0001). The maximum autofluorescence was related to lens coloration as well as to visual acuity only in nuclear cataract. The regression between maximum autofluorescence and light scatter was statistically significant only in the nuclear cataract group (p = 0.0004). Since the autofluorescence profiles differed not only in height but also in width between the cataract groups, various width/maximum autofluorescence ratios were measured. In nuclear and mixed cataract groups the ratio 75% width/maximum autofluorescence was statistically significantly lower than in other groups (p < 0.0001). In cortical cataracts the ratio (50% width - 75% width)/maximum autofluorescence was statistically significantly higher than in other groups (p < 0.0001).

Adult↗
PubMed1993

[Proper study of starting point in scientific philosophy--discussion of viewpoints in scholarly nursing study].

In this article starting points and methodological issues of qualitative research will be examined. Questions of phenomenology, analytic hermeneutics and so called newer hemeneutics are handled. Methodological roots of some Finnish PhD. dissertations will be identified. The main purpose of this paper is to discuss and make some clarification to conceptual diversity in studies using qualitative research methods.

Nursing Research↗
PubMed1991

Lens autofluorescence in healthy individuals.

We measured blue-green autofluorescence (AF, 495 nm/520 nm) of the lens in 43 random eyes of 43 healthy volunteers aged 6-86 years, five in each decade, using an instrument designed by one of us (HN). The instrument generates an autofluorescence profile, which consists of anterior and posterior juxtacortical peaks and a central plateau. The height of the anterior peak was taken as a maximum autofluorescence value and the square root of the ratio between the posterior and the anterior peak was used as a lens transmission index. The coefficient of variation for the measurement technique was 3.9% for maximum autofluorescence and 2.9% for lens transmission index. Both the maximum autofluorescence and the transmission index were highly correlated with age. Statistically over 90% of the variation in maximum autofluorescence values and almost 70% of the variation in transmission could be attributed to age.

Adolescent↗