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Biomedical subjects

M B Shapiro

Publications and source records attributed to M B Shapiro.

At least 19 recordsLinked to original sources
PubMed2000

Respiratory failure. Conventional and high-tech support.

Although significant progress has been made in the treatment of patients with acute lung failure in the critical care setting, the mortality rate from acute lung injury and ARDS is unacceptably high, given the numbers of patients treated for these syndromes each year. The improved understanding of the pathophysiology of respiratory failure from basic science and clinical research is reflected in improved survival rates over the years. Advances in the mechanical ventilator (through microprocessor technology); biosurface technology; liquid ventilation; and, in some cases, returning to so-called "antiquated" practices of patient care (e.g., prone positioning) seem to have had an impact nonetheless. As refinement continues to occur in these areas, morbidity and mortality from lung failure will have a lesser impact on patients as physicians treat the consequences of organ failure in the ICU.

Adult↗
PubMed2000

The injured elderly in the trauma intensive care unit.

The injured elderly patient in the ICU presents many challenges. Demographic changes in western society will dramatically increase the patient population in question, and new, older, subsets are growing. The association of severe injury, preinjury comorbidity, and the aging process narrows the ability of the patient to respond to the stress of injury. When compared with younger patients, the elderly have greater mortality, morbidity, and higher costs. Age alone, however, does not predict outcome. Although aggressive or maximally supportive care is advocated, controlled data supporting this approach are lacking. Significant economic, sociologic, and ethical issues confront the care providers in almost every case. Continued and heightened study of all aspects of our injured elders focusing on the determinants of outcome is required. A realistic appraisal of the limitations of care and a reassessment of the financial implications of providing extended care are critical to the continuing ability to respond to this growing need.

Adult↗
PubMed2000

Surgical airway management in the intensive care unit.

Despite having been a known surgical procedure for over 5000 years, the specifics of how, when, and why to perform a surgical airway are still debated. With new procedures, equipment, and techniques, operative airway management is becoming more complex. New methods of surgical airway management have to be evaluated against the gold standard, which will always be the open tracheostomy performed in the operating room. Unlike Dr. Jackson in 1909, surgeons today have to evaluate these new procedures not only by their efficacy but also by their cost effectiveness.

Airway Obstruction↗
PubMed2000

Blunt splenic injury in adults: Multi-institutional Study of the Eastern Association for the Surgery of Trauma.

BACKGROUND: Nonoperative management of blunt injury to the spleen in adults has been applied with increasing frequency. However, the criteria for nonoperative management are controversial. The purpose of this multi-institutional study was to determine which factors predict successful observation of blunt splenic injury in adults. METHODS: A total of 1,488 adults (>15 years of age) with blunt splenic injury from 27 trauma centers in 1997 were studied through the Multi-institutional Trials Committee of the Eastern Association for the Surgery of Trauma. Statistical analysis was performed with analysis of variance and extended chi2 test. Data are expressed as mean +/- SD; a value of p < 0.05 was considered significant. RESULTS: A total of 38.5 % of patients went directly to the operating room (group I); 61.5% of patients were admitted with planned nonoperative management. Of the patients admitted with planned observation, 10.8% failed and required laparotomy; 82.1% of patients with an Injury Severity Score (ISS) < 15 and 46.6% of patients with ISS > 15 were successfully observed. Frequency of immediate operation correlated with American Association for the Surgery of Trauma (AAST) grades of splenic injury: I (23.9%), II (22.4%), III (38.1%), IV (73.7%), and V (94.9%) (p < 0.05). Of patients initially managed nonoperatively, the failure rate increased significantly by AAST grade of splenic injury: I (4.8%), II (9.5%), III (19.6%), IV (33.3%), and V (75.0%) (p < 0.05). A total of 60.9% of the patients failed nonoperative management within 24 hours of admission; 8% failed 9 days or later after injury. Laparotomy was ultimately performed in 19.9% of patients with small hemoperitoneum, 49.4% of patients with moderate hemoperitoneum, and 72.6% of patients with large hemoperitoneum. CONCLUSION: In this multicenter study, 38.5% of adults with blunt splenic injury went directly to laparotomy. Ultimately, 54.8% of patients were successfully managed nonoperatively; the failure rate of planned observation was 10.8%, with 60.9% of failures occurring in the first 24 hours. Successful nonoperative management was associated with higher blood pressure and hematocrit, and less severe injury based on ISS, Glasgow Coma Scale, grade of splenic injury, and quantity of hemoperitoneum.

Adult↗
PubMed2000

Control variables in mechanical muscle models: a mini-review and a new model.

A new mechanical model of isolated muscle is proposed in which spring with variable slack length is the force-generating element. Based on the review of experimental studies in isolated muscle, it is suggested that spring slack length Xo is the control variable in the model and is a function of motor unit firing rate. In the presence of sensory feedback, the Sliding Spring model is equivalent to the Rack and Pinion model. However, sensory feedback is essential in the Rack and Pinion model but complementary in the Sliding Spring model. How the new control variable in the model of isolated muscle affects the interpretation of control processes up the motor system hierarchy is discussed in light of certain controversies associated with the Lambda and Alpha models of control of movement. It is argued that the Sliding Spring model of isolated muscle can be used as a basis for developing models of control of movement.

Biomechanical Phenomena↗
PubMed2000

Cerebral metabolic response to passive audiovisual stimulation in patients with Alzheimer's disease and healthy volunteers assessed by PET.

UNLABELLED: Alzheimer's disease is associated with reductions in resting-state brain metabolism, as measured by PET, progressing with dementia severity. The purpose of this study was to see to what extent brain regions with reduced resting-state metabolic rates in Alzheimer patients could be activated by a passive audiovisual stimulation test and to compare the result with activation in age-matched healthy volunteers. The extent of activation in Alzheimer's disease is considered to reflect the integrity of synaptic function, or inherent viability, and the potential responsiveness of the Alzheimer brain to drug therapy. METHODS: Regional cerebral metabolic rates for glucose (rCMRglc, in mg/ 100 g tissue/min) were measured in the resting state (eyes and ears covered) and during passive audiovisual stimulation (watching a movie) in 15 otherwise healthy Alzheimer patients of differing dementia severity (Mattis Dementia Rating Scale score, 23-128) and in 14 age-matched healthy volunteers (score, 141 +/- 3) using PET with 2 sequential injections of FDG. RESULTS: In the volunteers, audiovisual stimulation caused significant rCMRglc increases in visual and auditory cortical areas but significant decreases in frontal areas. In the mildly demented patients, rCMRglc responses were within 2 SDs of the mean in volunteers. However, the magnitude of the rCMRglc responses during stimulation declined significantly with dementia severity in the right occipitotemporal, right and left occipital association, and left calcarine cortical regions. CONCLUSION: Functional brain responsiveness, evaluated by a passive audiovisual stimulation paradigm with PET, is within normal limits in mildly demented Alzheimer patients but fails with worsening dementia severity. Declining responsiveness may account for the limited success of neurotransmitter replacement therapy in Alzheimer patients with moderate-to-severe dementia.

Acoustic Stimulation↗
PubMed1999

Time course and temporal order of changes in movement kinematics during learning of fast and accurate elbow flexions.

Learning of a motor task, such as making accurate goal-directed movements, is associated with a number of changes in limb kinematics and in the EMG activity that produces the movement. Some of these changes include increases in movement velocity, improvements in end-point accuracy, and the development of a biphasic/triphasic EMG pattern for fast movements. One question that has remained unanswered is whether the time course of the learning-related changes in movement parameters is similar for all parameters. The present paper focuses on this question and presents evidence that different parameters evolve with a specific temporal order. Neurologically normal subjects were trained to make horizontal, planar movements of the elbow that were both fast and accurate. The performance of the subjects was monitored over the course of 400 movements made during experiments lasting approximately 1.5 h. We measured time-related parameters (duration of acceleration, duration of deceleration, and movement duration) and amplitude-related parameters (peak acceleration, peak deceleration, peak velocity), as well as movement distance. In addition, each subject's reaction time and EMG activity was monitored. We found that reaction time was the parameter that changed the fastest and that reached a steady baseline earliest. Time-related parameters decreased at a somewhat slower rate and plateaued next. Amplitude-related parameters were slowest in reaching steady-state values. In subjects making the fastest movements, a triphasic EMG patterns was observed to develop. Our findings reveal that movement parameters change with different time courses during the process of motor learning. The results are discussed in terms of the neural substrates that may be responsible for the differences in this aspect of motor learning and skill acquisition.

Adult↗
PubMed1998

The efficacy of SimulVue and Unilens RGP aspheric bifocal contact lenses in the treatment of esotropia associated with a high accommodative convergence/accommodation ratio.

PURPOSE: This was a prospective study assessing the efficacy of the SimulVue bifocal contact lens and the Unilens RGP aspheric multifocal contact lens (Unilens, Largo, Fla.) in the treatment of high accommodative convergence/accommodation (AC/A) esotropia in an adolescent and postadolescent population. METHODS: Those patients meeting the inclusion criteria were fit with contact lenses with use of full cycloplegic refraction and later retested by an examiner masked to the previous binocular status. Particular attention was given to the sensory status and the motor fusion of each patient in their bifocal spectacles and then in their bifocal contact lenses. All patients were followed up for at least 6 months after the contact lenses were fitted. RESULTS: Five of the six patients demonstrated larger angles of esophoria or tropia at near with the contact lenses than with bifocal spectacles. The only patient who maintained excellent stereopsis in bifocal contact lenses was the one who normalized her AC/A ratio during this study and no longer required a bifocal in her spectacle correction for fusion. The two patients who initially had no stereopsis but good alignment in spectacle correction had a large esotropia at near fixation with bifocal contact lenses. CONCLUSIONS: The SimulVue and Unilens RGP aspheric bifocal contact lenses did not adequately treat adolescent patients who had esotropia associated with a high AC/A ratio.

Accommodation, Ocular↗
PubMed1998

Determining anatomic injury with computed tomography in selected torso gunshot wounds.

BACKGROUND: Changes in the management of torso gunshot wounds (TGSWs) have evolved in recent years as a result of differences between military and civilian injuries and increasing interest in avoiding nontherapeutic invasive procedures. The objective of this study was to establish the utility and accuracy of computed tomography (CT) in the evaluation of selected patients with TGSWs. METHODS: Retrospective review for a 6-year period of patients who sustained TGSWs and underwent CT solely for the purpose of trajectory determination. Patients had complete physical examinations and plain radiographic evaluations by a dedicated group of in-house trauma surgeons. When trajectory was indeterminate after evaluation, CT was performed. In some cases, CT was used when trajectory was determined to be intracavitary but organ injury was believed to be unlikely or amenable to nonoperative management. RESULTS: Fifty TGSW patients underwent 52 computed tomographic scans. Abdominal/pelvic CT was performed in 37 patients, and thoracic CT was performed in 15 patients. All patients were stable and none sustained complications attributable to CT or delay in therapy. Twenty of 37 abdominal/pelvic computed tomographic scans excluded transabdominal or pelvic trajectory. Seventeen of 37 scans proved transabdominal or pelvic trajectory; nine laparotomies were performed, and eight patients were observed. Nine of 15 thoracic computed tomographic scans excluded transmediastinal trajectory. Six of 15 scans suggested vascular proximity and prompted further workup, which was positive in two cases. CONCLUSION: CT of selected TGSW patients is safe and may reduce the incidence of invasive diagnostic procedures. A prospective evaluation of CT for TGSW patients is warranted.

Abdominal Injuries↗
PubMed1998

Treatment of brain tumors in children is associated with abnormal MR spectroscopic ratios in brain tissue remote from the tumor site.

PURPOSE: Children who have brain tumors are at risk for a variety of treatment-related sequelae, including neuropsychological and cognitive impairment, neurologic deficits, and neuroendocrinologic disturbances. We sought to determine the value of proton MR spectroscopy in assessing brain tissue remote from the tumor site to ascertain the effects of chemotherapy and radiation treatment in these patients. METHODS: Single-voxel proton MR spectra from 70 patients (111 spectra) and 11 healthy volunteers (11 spectra) were analyzed. NAA/Cr, NAA/Cho, and Cho/Cr ratios based on peak areas were obtained from nonneoplastic regions of the frontal lobe. The relationship between MR spectroscopic ratios and treatment was determined. RESULTS: NAA-containing ratios were decreased in patients as compared with control subjects. The presence of gadolinium-based contrast material did not cause significant changes in the ratios as compared with precontrast data. When chemotherapy was a component of a child's treatment protocol, we found a significant decline in NAA/Cr ratios. Patients who underwent both chemotherapy and radiation therapy showed a trend toward lower NAA-containing ratios if the chemotherapy was administered before the radiation therapy. Patients receiving whole-brain radiation had a trend toward lower NAA-containing ratios than did those who had only focal tumor treatment. CONCLUSION: In children with brain tumors, MR spectroscopy of brain tissue remote from the tumor reveals treatment-related biochemical changes.

Adolescent↗
PubMed1997

Solid viscus injury predicts major hollow viscus injury in blunt abdominal trauma.

BACKGROUND: As nonoperative management of blunt abdominal trauma has become more popular, reliable models for predicting the likelihood of concomitant hollow viscus injury in the hemodynamically stable patient with a solid viscus injury are increasingly important. METHODS: The Pennsylvania Trauma Systems Foundation registry was reviewed for the period from January 1992 to December 1995 for all adult (age > 12 years) patients with blunt trauma and an Abbreviated Injury Scale (AIS) score > or = 2 for a solid viscus (kidney, liver, pancreas, spleen). Patients with an initial systolic blood pressure < 90 mm Hg were excluded. Hollow viscus injuries included only lacerations or perforations of the gallbladder, gastrointestinal tract, or urinary tract. RESULTS: In the 4-year period, 3,089 patients sustained solid viscus injuries, 296 of whom had a hollow viscus injury (9.6%). The mean age was 35.6 years, mean Injury Severity Score was 22.2, and mean Revised Trauma Score was 7.3; 63.3% of the patients were male. A solitary solid viscus injury occurred in 2,437 patients (79%), 177 of whom (7.3%) had a hollow viscus injury. The frequency of hollow viscus injury increased with the number of solid organs injured: 15.4% of patients with two solid viscus injuries (n = 547) and 34.4% of patients with three solid viscus injuries (n = 96) suffered a concomitant hollow viscus injury (p < 0.001 vs. one organ). A hollow viscus injury was 2.3 times more likely for two solid viscus injuries and 6.7 times more likely for three solid viscus injuries compared with a solitary solid viscus injury. For solitary solid viscus injury, the frequency of hollow viscus injury varied little with increasing AIS score (AIS score 2, 6.6%; AIS score 3, 8.2%; AIS score 4, 9.2%; AIS score 5, 6.2%) (p = 0.27 between groups), suggesting that the incidence of hollow viscus injury is related more to the number of solid visceral injuries than the severity of individual organ injury. Also, when the sum of the AIS scores for solid viscus injuries was <6, the mean rate of hollow viscus injury was 7.8%. This increased to 22.8% when the sum of the AIS scores for solid viscus injury was > or =6 (p < 0.001). A pancreatic injury in combination with any other solid viscus injury had a rate of hollow viscus injury of >33%. CONCLUSION: A model of organ injury scaling predicted hollow viscus injury. Multiple solid viscus injuries, particularly pancreatic, or abdominal solid viscus injuries with an AIS score > or = 6, were predictive of hollow viscus injury. Identification of these injury patterns should prompt consideration for early operative intervention.

Abbreviated Injury Scale↗
PubMed1996

Effect of stimulation in the ventral intermediate nucleus of the thalamus on limb control in Parkinson's disease: a case study.

This study focuses on upper extremity strength and movement control in a patient with Parkinson's disease who had stimulating electrodes surgically implanted in the ventral intermediate nucleus (VIM) of the left thalamus. We examined torque generation and control of movement distance in single degree-of-freedom elbow movements under three different stimulation conditions: (a) no stimulation, (b) high stimulation, in which tremor was minimized but there was also tingling and perceived weakness, and (c) moderate stimulation, in which tremor was partially reduced, but there was also a subjective sense of increased strength compared with the high-stimulation condition. The patient's ability to generate both steady torque and rapid movements was poorest with no stimulation. The patient generated the largest torques with moderate stimulation and performed the fastest movements with high stimulation. However, even with tremor minimized, the patient's electromyogram (EMG) burst patterns were not typical of those of neurologically healthy subjects, although the movements were clearly improved.

Elbow↗
PubMed1995

Feedforward postural adjustments in a simple two-joint synergy in patients with Parkinson's disease.

Patients with Parkinson's disease, age-matched controls and young control subjects performed discrete elbow or wrist movements in a sagittal plane under the instruction to move one of the joints "as fast as possible." Relative stability of the other, postural joint was comparable in all 3 groups, while movement time was the highest in the patients and the lowest in young controls. Typically, EMG patterns in both muscle pairs acting at the joints demonstrated a commonly observed "tri-phasic" pattern. A cross-correlation analysis of the EMGs confirmed virtually simultaneous bursts in the wrist and elbow flexors and in the wrist and elbow extensors. In all 3 groups, there were no signs of anticipatory activation of postural muscles in about 90% of movements. We consider postural anticipation not a separate process, but a separate peripheral pattern of a single control process that may involve a number of joints and muscles. We conclude that the postural deficits in Parkinson's disease are not related to a basic deficit in the ability to generate feedforward postural adjustments but to other factors that may include the specificity of maintaining the vertical posture in the field of gravity.

Aged↗
PubMed1995

Emergency cricothyrotomy: a reassessment.

The Medical College of Georgia Level I Trauma Center admitted 5603 adult trauma patients from January 1, 1989 through June 30, 1993. Cricothyrotomy was required in 66 of 525 patients who required emergency airway control but could not be intubated nonsurgically in an expeditious manner. There were three major complications (thyroid cartilage laceration, significant hemorrhage, and failure to obtain a surgical airway) involving two patients, but each resolved without sequelae. Twenty-six patients with cricothyrotomy survived their hospital course, of which seven had decannulation of the cricothyrotomy without further airway procedures, and 19 had conversion to tracheostomy. No patient had clinically significant morbidity from the cricothyrotomy, whether with or without a subsequent tracheostomy. Surgical cricothyrotomy remains an important technique with low morbidity for selected trauma victims needing emergency airway control.

Adult↗
PubMed1994

Visual disturbances associated with oval-optic poly(methyl methacrylate) and round-optic silicone intraocular lenses.

A prospective, randomized, double-masked clinical trial of 182 patients compared the frequency of visual disturbances associated with two small incision intraocular lenses (IOLs): the Alcon MZ20BD 5 mm x 6 mm oval-optic poly(methyl methacrylate) (PMMA) IOL and the STAAR AQ1016 round-optic silicone IOL. The samples were similar at baseline. There were no significant differences in visual acuity, mean keratometric cylinder, or surgically induced cylinder between the two groups postoperatively. Patients completed a satisfaction questionnaire and visual symptom inventory of ten items three months postoperatively. Those with the oval-optic PMMA IOL reported significantly more visual symptoms than those with the round-optic silicone IOL (P = .03). The oval-optic group reported three symptoms more frequently: reflections, halos or rings around lights, and objects at arm's length appearing blurry (P < or = .010). The status of the fellow eye (cataract or pseudophakic) did not differ by randomization group, and the distribution of visual symptoms did not differ by status of the fellow eye. Frequency and severity of visual complaints were modest overall; only 1% in each group was unsatisfied with the visual results.

Adult↗