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Hemodynamic exercise response in calves with an implantable biventricular centrifugal blood pump.

An implantable biventricular assist device (BVAD) has been developed at Baylor College of Medicine using 2 centrifugal blood pumps. The aim of this study was to investigate the exercise-reflex response during nonpulsatile biventricular assistance and to evaluate to which degree the autoregulation of the system would accommodate the changed hemodynamic situation during physical exercise. The Baylor Gyro PI 710 BVAD has been implanted into 2 calves (strain half-Dexter) in a biventricular bypass fashion with native heart remaining. Allowing a 10 day convalescence, 2 animals were subjected to incremental exercise tests. The speed of the treadmill was increased at zero slope from 0.7 mph to 1.5 mph with increments of 0.2 mph every 3 min. During the exercise the pump flows were maintained at a fixed rate (6.93 +/- 0.01 L/min for the left ventricular assist device and 5.36 +/- 1.44 L/min for the right ventricular assist device). Hemodynamic parameters and pump performance were recorded continuously. The cardiac output (CO) and heart rate (HR) increased significantly during the exercise. CO increased from 11.1 +/- 0.3 to 13.1 +/- 0.4 L/min, and HR increased from 99 +/- 7.1 to 114 +/- 2.8 bpm, respectively. Mean aortic pressure, central venous pressure, and left arterial pressure did not change significantly. Also, no change was observed for the left and right pump flows. This totally implantable BVAD showed excellent long-term performance without any mechanical problems. It is feasible to operate without impairment under physical activity. However, the natural heart dominated the hemodynamic response during exercise under BVAD support. The left and the right pump flows did not increase spontaneously with exercise. We therefore conclude that a servo CO control system is necessary to regulate pump flows even during moderate exercise.

Animals↗

Development of the Baylor Gyro permanently implantable centrifugal blood pump as a biventricular assist device.

The Baylor Gyro permanently implantable centrifugal blood pump (Gyro PI pump) has been under development since 1995 at Baylor College of Medicine. Excellent results were achieved as a left ventricular assist device (LVAD) with survival up to 284 days. Based on these results, we are now focusing on the development of a biventricular assist device (BVAD) system, which requires 2 pumps to be implanted simultaneously in the preperitoneal space. Our hypothesis was that the Gyro PI pump would be an appropriate device for an implantable BVAD system. The Gyro PI 700 pump is fabricated from titanium alloy and has a 25 ml priming volume, pump weight of 204 g, height of 45 mm, and pump diameter of 65 mm. This pump can provide 5 L/min against 100 mm Hg at 2,000 rpm. In this study, 6 half-Dexter healthy calves have been used as the experimental model. The right pump was applied between the infundibular of the right ventricle and the main pulmonary artery. The left pump was applied between the apex of the left ventricle and the thoracic descending aorta. As for anticoagulation, heparin was administered at the first postoperative week and then converted to warfarin sodium from the second week after surgery. Both pump flow rates were controlled maintaining a pulmonary arterial flow of less than 160 ml/kg/min for the sake of avoidance of pulmonary congestion. Blood sampling was done to assess visceral organ function, and the data regarding pump performance were collected. After encountering the endpoint, which the study could not keep for any reasons, necropsy and histopathological examinations were performed. The first 2 cases were terminated within 1 week. Deterioration of the pump flow due to suction phenomenon was recognized in both cases. To avoid the suction phenomenon, a flexible conduit attached on the inlet conduit was designed and implanted. After using the flexible inflow conduit, the required power and the rotational speed were reduced. Furthermore, the suction phenomenon was not observed except for 1 case. There was no deterioration regarding visceral organ function, and pulmonary function was maintained within normal range except for 1 case. Even though the experimental animal survived up to 45 days with the flexible inflow conduit, an increase in power consumption due to thrombus formation behind the impeller became a problem. Lower rotational speed, which was probably produced by the effectiveness of the flexible inflow conduit, was speculated to be one of the reasons. And the minimum range of rotational speed was 1,950 rpm in these 6 BVAD cases and the previous 3 cases of LVAD. In conclusion, 6 cases of BVAD implantation were performed as in vivo animal studies and were observed up to 45 days. The flexible inflow conduit was applied in 4 of 6 cases, and it was effective in avoiding a suction phenomenon. The proper rotational speed of the Gyro PI 700 pump was detected from the viewpoint of antithrombogenicity, which is more than 1,950 rpm.

Animals↗

Extracorporeal membrane oxygenator compatible with centrifugal blood pumps.

Coil-type silicone membrane oxygenators can only be used with roller blood pumps due to the resistance from the high blood flow. Therefore, during extracorporeal membrane oxygenation (ECMO) treatment, the combination of a roller pump and an oxygenator with a high blood flow resistance will induce severe hemolysis, which is a serious problem. A silicone rubber, hollow fiber membrane oxygenator that has a low blood flow resistance was developed and evaluated with centrifugal pumps. During in vitro tests, sufficient gas transfer was demonstrated with a blood flow less than 3 L/min. Blood flow resistance was 18 mm Hg at 1 L/min blood flow. This oxygenator module was combined with the Gyro C1E3 (Kyocera, Japan), and veno-arterial ECMO was established on a Dexter strain calf. An ex vivo experiment was performed for 3 days with stable gas performance and low blood flow resistance. The combination of this oxygenator and centrifugal pump may be advantageous to enhance biocompatibility and have less blood trauma characteristics.

Animals↗

Age and features of movement influence motor overflow.

OBJECTIVES: To measure the magnitude and prevalence of motor overflow to the arm at rest during attempted unilateral arm movements. DESIGN: Cross-sectional assessment. SETTING: Motor physiology laboratory. PARTICIPANTS: Healthy young (n=20) and elderly (n=20) adult subjects. MEASUREMENTS: Surface electromyography (EMG) was obtained from bilateral forearm muscles during performance of 12 different unilateral finger-tapping tasks. RESULTS: For all subjects, faster movement rate (F=2.56-3.30, P<.05), cognitive distraction (F=4.09, P<.05), and fatigue (F=15.15, P<.001) were each associated with a significant increase in the magnitude of EMG in the arm intended to be at rest. In elderly subjects, tapping at maximum rate and fatigue were each associated with a further increase in motor overflow across the midline. In addition, better left hand dexterity correlated with greater motor overflow to the right hand during rapid left hand tapping (r=0.63, P<.005). Prevalence of motor overflow was also higher in older subjects for some tasks, for example during 1 Hz tapping by the right index finger (motor overflow present in 45%, vs 15% young subjects, P<.05). CONCLUSION: Several behavioral variables increase motor overflow across the midline in young and elderly adults. Motor overflow was even greater in elderly subjects with the most demanding tasks and was greater in those with better motor status, suggesting that this form of motor system change is a compensatory event of normal aging rather than age-related dysfunction. The results support the hypotheses that healthy aging is associated with an increase in the degree to which brain function is bilaterally organized.

Adult↗

Effects of upper limb unilateral isometric efforts on postural stabilization in subjects with hemiparesis.

OBJECTIVE: To characterize postural stabilization during a progressive unilateral isometric abduction of the upper limb in a seated position in healthy subjects and subjects with hemiparesis. DESIGN: Convenience sample. SETTING: University secondary care rehabilitation center. PATIENTS: Twelve patients with hemiparesis and 12 subjects without neurologic disorder. INTERVENTIONS: Subjects were seated on a forceplate, with forearms fixed in cuffs mounted on a force transducer. Two trials per side of isometric abduction of arm were conducted. The orthogonal force and torque exerted was measured for each arm. MAIN OUTCOME MEASURES: Forces at the upper limbs and at the seat, global motor performance, spasticity of upper limb, grip force, and dexterity. RESULTS: Results of analyses of variance showed differences in the magnitude of the contralateral limb forces generated by subjects with hemiparesis and healthy subjects (p <.05). Normalized contralateral forces in the nonparetic upper limb associated with paretic isometric efforts were higher than those associated with nonparetic efforts and higher than those associated with efforts in healthy subjects. CONCLUSION: These results suggest that postural stabilization during isometric efforts is impaired in subjects with hemiparesis.

Adult↗

Sensory motor retuning: a behavioral treatment for focal hand dystonia of pianists and guitarists.

OBJECTIVE: To evaluate the long-term effectiveness of sensory motor retuning (SMR), a new treatment for focal hand dystonia in musicians. DESIGN: Prospective case series with an (adventitious) comparison group with 3- to 25-month follow-up in piano and guitar and 0- to 4-month follow-up in flute and oboe players. SETTING: General community in Germany. PARTICIPANTS: Eleven professional musicians. INTERVENTION: Immobilization by splints of 1 or more digits other than the focal dystonic finger. This finger carried out repetitive exercises in coordination with 1 or more of the other digits for 1(1/2) to 2(1/2) hours a day for 8 consecutive days under therapist supervision. The subjects then were instructed to continue practice for 1 hour daily for 1 year. MAIN OUTCOME MEASURES: Spectral analysis of the output of a dexterity-displacement device that continuously recorded digital displacement during finger movements and a dystonia evaluation scale on which patients rated how well they had just performed dystonic movement sequences and repertoire passages. RESULTS: The 3 wind players (adventitious placebo controls) did not improve substantially. However, each pianist and guitarist showed marked and significant improvement in spontaneous repertoire performance without the splint. The first subject is now 25 months posttreatment. CONCLUSIONS: Results suggest that SMR is of value for the treatment of focal hand dystonia in pianists and guitarists.

Adult↗

A model instrument for the documentation of outcome after nerve repair.

We present a new model for documentation and quantification of the functional outcome after nerve repair at the wrist or distal forearm level and a protocol that includes a numerical scoring system. The model, presented here along with validation and reliability test results, supports our hypothesis that the summarized test results reflecting specific functional limitations correlates well with the patient's opinion of the impact of the nerve injury on activities of daily living. Seventy patients with nerve repair were examined using the protocol. Analysis included 3 factors: sensory domain (sensory innervation, tactile agnosis, and finger dexterity), motor domain (motor innervation and grip strength), and pain/discomfort domain (hyperaesthesia and cold intolerance). The analysis explained 73% of the variances of the variables and the variables had a logical distribution between the factors. Analysis of internal consistency demonstrated good homogeneity. A calculated total score correlated strongly with the patients' global estimation of the impact of the injury on activities of daily living and the summary of sensory and pain/discomfort domains correlated significantly with the Medical Research Council S0-S4 scale. The presented model represents a useful new tool for evaluation of the functional outcome after nerve injury and repair.

Adolescent↗

An outcome study of thumb reconstruction using microvascular toe transfer.

The purpose of this study was to evaluate outcomes following microvascular toe to thumb transfer in a cohort study using the Michigan Hand Outcomes Questionnaire, the 36-item Short-Form Health Survey, the Lower Limb Function Questionnaire, and standardized hand function tests. Twenty-one patients who had unilateral, isolated thumb amputations at the metacarpophalangeal joints were studied: 16 patients had toe transfer and 5 patients did not have reconstruction. The mean follow-up period was 7.2 years (range, 3-13 years). Toe transfer patients showed statistically significantly better overall hand function (effect size = 1.4), ADL (effect size = 3.4), work performance (effect size = 2.1), aesthetics (effect size = 1.9), and satisfaction (effect size = 1.1). Functional testing showed that strength and dexterity of the toe transfer hands were comparable to the opposite normal hands. Foot donor site morbidity was minimal. No significant difference was found in the mean Lower Limb Function Questionnaire scores between the toe transfer patients (1.4) and the amputation patients who did not undergo reconstruction (1.6). The results of our study showed that patients with toe transfer have better hand function than patients with thumb amputations at the level of the metacarpophalangeal joints.

Adult↗

Responsiveness of the short form-36, disability of the arm, shoulder, and hand questionnaire, patient-rated wrist evaluation, and physical impairment measurements in evaluating recovery after a distal radius fracture.

We evaluated the responsiveness of patient questionnaires and physical testing in the assessment of recovery after distal radius fracture. Patients (n = 59) were assessed at their baseline clinic visit and again 3 and 6 months after injury. At each visit patients completed a short form-36, Disability of the Arm, Shoulder, and Hand questionnaire, and patient-rated wrist evaluation (PRWE). At 3 and 6 months grip strength, range of motion, and dexterity were analyzed. Standardized response means (SRM) and effects sizes were calculated to indicate responsiveness. The PRWE was the most responsive. Both the PRWE (SRM = 2.27) and the Disability of the Arm, Shoulder, and Hand (SRM = 2.01) questionnaire were more responsive than the short form-36 (SRM = 0.92). The physical component summary score of the short form-36 was similar to that of the physical component subscales. Questionnaires were highly responsive during the 0- to 3-month time period when physical testing could not be performed. Of the physical tests, grip strength was most responsive, followed by range of motion. Responsive patient-rating scales and physical performance evaluations can assist with outcome evaluation of patients with distal radius fracture.

Adolescent↗

Historical perspective of finger joint motion: the hand-me-downs of our predecessors. The Richard J. Smith Memorial Lecture.

Understanding the mechanics of human dexterity requires an appreciation of the kinetic chains that comprise the hand and the intricate interplay of muscles and ligaments that control its movements. Some of the salient contributions to this field are described from a personal point of view in the hope that this perspective will stimulate further understanding of this unique human tool.

Finger Injuries↗

Hematoma and distraction arthroplasty for thumb basal joint osteoarthritis: a prospective, single-surgeon study including outcomes measures.

PURPOSE: Many surgeons have abandoned the simple trapeziectomy as a surgical treatment option for thumb basal joint arthritis secondary to reports of postoperative weakness. The thumb metacarpal subsiding into the trapezial void has been proposed as the causative factor. The goal of the present study was to evaluate the results of trapeziectomy and postoperative K-wire immobilization of the thumb metacarpal in a distracted position without the use of ligament reconstruction or tendon interposition. METHODS: Twenty-six thumbs in 26 patients from a single surgeon's practice were entered into a prospective single-arm study for surgical treatment of peritrapezial arthritis. Treatment consisted of piecemeal excision of the entire trapezium and 5 weeks of K-wire immobilization of the first metacarpal in slight distraction and opposition. No ligament reconstruction or tendon interposition was used. Motion, strength, stress radiographs, standardized dexterity tests, and outcomes questionnaires including the Arthritis Impact Measurement Scales 2 (AIMS2) were evaluated before surgery and 6 and 24 months after surgery. RESULTS: At 6 months 19 of 26 patients (73%) reported complete relief of pain and at 24 months 92% were entirely pain free. Range of motion evaluation showed 24 of 26 thumbs adducted fully into the plane of the palm and 25 of 26 opposed to the fifth metacarpal head. Comparisons between preoperative and 24-month postoperative strength measurements showed an average 47% increase in grip strength, 33% increase in key pinch strength, and a 23% increase in tip pinch strength over preoperative values. AIMS2 data showed postoperative improvement in "hand and finger function" and "arthritis pain" scales. CONCLUSIONS: After trapezial excision K-wire immobilization in a slightly overcorrected position without tissue interposition or ligament reconstruction restores a stable, pain-free thumb that has superior strength and motion compared with published reports of the more complicated interventions.

Aged↗

Cognitive deficits in school-age children with severe short bowel syndrome.

BACKGROUND/PURPOSE: Improved therapies for the management of short bowel syndrome (SBS) have resulted in the prolonged survival of many children. By early childhood, the physiological sequelae of severe SBS include delayed physical development and metabolic imbalances. However, little is known about how SBS affects brain development. Although many parents report school problems, no controlled study has evaluated the integrity of the central nervous system in SBS children. The purpose of this study was to investigate the neuropsychological status of school-aged SBS children to determine if there were characteristic cognitive impairments that might be amenable to early therapeutic intervention. METHODS: SBS children (n = 8; mean age, 116.9 +/- 21 months) were compared with an age-matched cystic fibrosis (CF) control group (n = 8; mean age, 118.1 +/- 14 months). Groups did not differ in age, grade, or absences. Neuropsychological tests with established sensitivity to CNS integrity compared performance over 6 cognitive domains. Emotional status also was measured. Analyses were completed with 2-tailed t tests. RESULTS: Groups did not differ on tests of intellectual ability and emotional function. Language, memory and learning, and problem-solving testing results indicated no significant group differences. However, the SBS group performed more poorly on measures assessing visual-spatial ability, with P values ranging from .002 to .045. In a subset of subjects, we noted significantly slower left-handed, but not right-handed, performance on measures of finger dexterity and psychomotor speed. CONCLUSIONS: Although emotional status did not differ from that of children with CF, SBS patients showed visual-spatial deficits in the company of preserved language, attention and memory, and executive skills. The specificity and consistency of these findings suggests that right hemisphere CNS changes may occur in children with SBS. This unexpected finding, coupled with the indication of left-sided psychomotor slowing in right-handed subjects, raises the possibility that actual brain impairment, rather than developmental delay accompanying slowed physical growth, accounts for these findings. Longitudinal studies are needed to further clarify this issue. The educational significance of the results is discussed.

Child↗

Impulsive Homicide Associated With an Arachnoid Cyst and Unilateral Frontotemporal Cerebral Dysfunction.

A 65-year-old man with no past history of violent or criminal behavior abruptly strangled his wife after she scratched his face during a domestic argument. He appeared emotionally blunted and lacked insight into the motivations for his violent actions. The presence of left-sided cerebral dysfunction was initially suggested by subtly decreased dexterity of his dominant right hand. A magnetic resonance image (MRI) revealed a large arachnoid cyst centered in his left Sylvian fissure that effaced ventral frontal, anterior temporal and insular cortical gyri. The left middle cerebral artery was displaced relative to an earlier study, providing indirect evidence that the cyst had enlarged during his adult life. Neuropsychological testing indicated generally intact cognitive abilities except for mild impairment on tests of prospective memory and executive functions. He was found to have intermittently decreased EEG amplitude in the left fronto-temporal region. Positron emission tomography (PET) revealed significantly reduced resting glucose metabolism in the left frontal and temporal lobes. He was also found to have pathological diminution of autonomic responses to affectively charged visual stimuli, a phenomenon previously reported in patients with ventromedial frontal lobe injury and acquired disturbances of social conduct. In light of these findings, we suggest that his violent behavior represents stimulus-bound aggression, triggered by a novel physical threat and unchecked by learned social restraints owing to the presence of ventral prefrontal dysfunction.

Journal Article↗

Nonsurgical periodontal therapy.

The primary etiology of periodontal disease is bacterial infection. Bacteria exist as a biofilm (plaque) on the tooth and soft-tissue surfaces of the mouth. Biofilm is extremely resistant to antimicrobial activity. To effectively treat periodontal disease, the bacterial load must be reduced to allow healing of the inflamed tissues. Reduction of the bacterial load can be accomplished by surgical methods, nonsurgical methods, or a combination of the two. This article focuses on the nonsurgical treatment of periodontal disease. A thorough oral examination, which includes visual inspection and the use of a periodontal probe, is needed to determine the best therapy. Supragingival cleaning with power and hand scalers is the first step in the therapy process. The next step, subgingival scaling, is necessary to remove bacteria that are in direct contact with the periodontium. Effective subgingival plaque removal is time intensive and requires motivation, manual dexterity, and meticulous technique. Most veterinarians and veterinary technicians lack the training, instruments, and time to remove subgingival plaque effectively. To improve therapeutic results, adjunctive therapy in the form of oral systemic antibiotics or a locally applied doxycycline-containing polymer may be used. The success of periodontal therapy also is dependent on dental home care that takes place after professional treatment. The veterinarian and staff must be willing to educate and reinforce the dental home care efforts of the pet owner.

Animals↗

Why do we speak with the left hemisphere?

Human language tends to be associated with circuitry in the left cerebral hemisphere, regardless of individual hand dominance. This may have resulted from the coevolution of language and dexterous manipulation, specifically the use of the dominant hand to direct forces and point to objects in the environment. Asymmetric manipulation of physical objects reflects a fundamental asymmetry of perceptual-motor brain circuitry, which in turn results from the nature of the mechanical interaction between the organism and its environment. The natural selection of more effective manipulative ability, especially in the form of tool use, strengthened the fundamental organismal asymmetry, leading to distinct handedness and hemispheric dominance for manipulation and language in humans. The related subject of ocular dominance is also discussed.

Animals↗

[Lymphography in childhood (author's transl)].

Fifty-one lymphograms were performed in children; the indications, technique and results are discussed. Indications are the search for retroperitoneal involvement in lymphogranulomatosis, lympho-sarcoma and reticulum cell sarcoma; in the search for metastases from malignant tumours, particularly abdominal neuroblastoma, soft tissue sarcomas of the abdomen and lower extremities, testicular tumours and malignant melanomas and finally, for primary lymph-oedema and lymphangiomas. Technique is the same as for adults, but requires particular manual dexterity. Children under six years require general anaesthesia. Amongst 28 children with malignant lymphomas, pathological changes in the retroperitoneal lymph nodes were found in seven. In six, this resulted in a change of the staging. Five out of 16 lymphograms in children with malignant tumours showed evidence of lymph node metastases. All six lymphangiograms in children with lymphoedema and lymphangiomas were abnormal.

Abdominal Neoplasms↗

[Initial results of treatment with the new AO wrist joint arthrodesis plate].

Although diagnosis and therapeutic options for post-traumatic, idiopathic, and degenerative wrist arthropathies have improved during recent years, total wrist fusion is still frequently regarded as a popular option of treatment. Fourty-one patients underwent wrist arthrodesis between May 1994 and April 1996 using the recently introduced new AO-plate after earlier wrist trauma or Kienböck's disease. Thirty-five patients were examined. The average follow-up time was 15 months. Hand function and active digital range of motion (ADROM) was assessed clinically, grip strength was measured using a Jamar-Dynamometer and the Dexter-Computer-System. Patient's daily activities and general postoperative quality of life were estimated with the new DASH-questionnaire. It can be concluded from our data, that the widely claimed complete pain relief after total wrist fusion does not match reality. Eighty percent of the patients complained about reduction of postoperative quality of life with impaired personal hygiene and functional deficits; however, the majority would undergo the procedure again. Seventy percent of the patients returned to their original occupation. The DASH-questionnaire proved to be a very useful and sensitive tool for evaluating the patient's problems at the upper extremity.

Adult↗

Troubleshooting and managing the difficult airway.

Difficult airways are an inevitable part of the delivery of emergency and critical care. Failure to achieve or restore a patent airway can lead, in a matter of minutes, to hypoxic neurological injury and death in critically ill patients. As with many conditions, the keys to success in a moment of crisis are forethought and preparation. Clinicians should be able to recognize risk factors for difficult airways and plan accordingly. In the face of failed direct laryngoscopy, a variety of rescue techniques are available. Familiarity with many strategies, and practiced dexterity with one or two, should be part of every intensivist's plan for the management of this life-threatening problem.

Journal Article↗