PubMed Health⌕ Search

Biomedical subjects

J A Katz

Publications and source records attributed to J A Katz.

At least 19 recordsLinked to original sources
PubMed1994

Safety and cost effectiveness of early hospital discharge of lower risk children with cancer admitted for fever and neutropenia.

BACKGROUND: Standard treatment for fever during periods of chemotherapy-induced neutropenia includes hospitalization and administration of intravenous antibiotics until the patient is afebrile and no longer neutropenic. This study prospectively evaluates the safety and cost-effectiveness of early discharge of selected low risk children before recovery from neutropenia. METHODS: We studied 74 children with cancer during 131 consecutive admissions for fever during a period of neutropenia. All patients initially were hospitalized and received broad-spectrum antibiotics. Intravenous antibiotic therapy was discontinued, and the patients promptly were discharged even if they had an absolute neutrophil count (ANC) of less than 500 cells/mm3 as long as they were afebrile, appeared clinically well, had negative cultures, exhibited control of local infection, and showed hematologic evidence of bone marrow recovery. RESULTS: Intravenous antibiotics were discontinued in 82 cases (63%) before recovery of the ANC to more than 500 cells/mm3, and 78 patients were discharged immediately. None of 70 patients discharged while neutropenic but exhibiting a rising ANC at the time of discharge developed recurrent fever and required readmission. Thirty of these children had an improving localized infection when intravenous antibiotics were discontinued and completed a course of oral antibiotics at home. The estimated mean savings in hospital charges due to early discharge was $5058 per patient. CONCLUSIONS: Low risk children with cancer who are hospitalized and treated for fever and neutropenia but appear clinically well may have intravenous antibiotics discontinued and be discharged safely irrespective of the ANC, as long as their granulocyte count is rising. This approach shortens hospital stays and results in considerable cost savings.

Adolescent↗
PubMed1994

Thermoregulatory and anesthetic-induced alterations in the differences among femoral, radial, and oscillometric blood pressures.

BACKGROUND: A decrease in radial artery blood pressure relative to central arterial blood pressure is commonly associated with the rewarming phase of cardiopulmonary bypass. Decreased hand vascular resistance has been suggested as a possible mechanism. Although decreased blood viscosity due to hemodilution may contribute to decreased hand vascular resistance, thermoregulatory vascular responses to core hyperthermia also may be important. METHODS: Seven healthy volunteers were studied. Volunteers first were cooled until thermoregulatory vasoconstriction was evident. Next, each was warmed until intense sweating developed. After a cool-down period, general anesthesia was induced with propofol and N2O. Femoral artery pressure (a surrogate for central arterial pressure) and radial artery and oscillometric (brachial artery) pressures were compared during each of six defined thermoregulatory and anesthetic study conditions. To determine the effect of hand vascular resistance on blood pressure differences, measurements were compared before and after occlusion of hand blood flow. Upper-extremity blood flow was evaluated by forearm and fingertip plethysmography and laser Doppler flowmetry. RESULTS: Forearm, fingertip, and cutaneous blood flow increased significantly during warming and were maximal during intense sweating. During thermoregulatory vasoconstriction, femoral, radial, and oscillometric mean blood pressures were similar. In contrast, radial artery mean pressure was 5 +/- 1 mmHg less than femoral artery mean pressure and 12 +/- 8 mmHg less than oscillometric mean pressure during intense sweating. Hand compression reduced these differences. The contour of the radial artery pressure waveform was dramatically altered by thermoregulatory and anesthetic conditions. Radial artery systolic pressure exceeded both femoral artery and oscillometric systolic pressures during vasoconstriction but was less than these during intense sweating. Hand compression reestablished the exaggerated radial artery systolic pressure during all study conditions. CONCLUSIONS: Thermoregulatory and anesthetic-induced alterations in upper-extremity blood flow substantially influence the relations among femoral artery, radial artery, and oscillometric blood pressure measurements.

Adult↗
PubMed1994

The effects of azidothymidine therapy on pseudocholinesterase concentrations in asymptomatic HIV-positive patients.

The purpose of this study was to determine if a correlation exists between long-term azidothymidine (AZT) therapy and low pseudocholinesterase concentrations in patients who are infected with the human immunodeficiency virus (HIV). A pilot study was conducted of 10 patients infected with HIV, 5 of whom were receiving AZT. Laboratory tests, including complete blood count (CBC), liver function tests, helper/inducer T lymphocyte numbers (CD4), serum dibucaine numbers, and serum pseudocholinesterase concentrations were examined. Control and study subjects both exhibited normal dibucaine numbers, but the pseudocholinesterase concentrations were significantly lower in the group that was not receiving AZT relative to the AZT treatment group. However, only two patients, neither of whom were receiving AZT, demonstrated low or borderline low pseudocholinesterase concentrations according to laboratory criteria. It is possible that pseudocholinesterase synthesis is significantly inhibited by the HIV disease process and that treatment with AZT partly reverses the inhibition. Associated variables contributing to low pseudocholinesterase concentrations in the HIV-positive patient are explored.

Adult↗
PubMed1992

Value of C-reactive protein determination in the initial diagnostic evaluation of the febrile, neutropenic child with cancer.

We studied prospectively the value of administration C-reactive protein (CRP) in the diagnostic evaluation of the child with cancer hospitalized for fever and neutropenia. During a 7-month period 74 patients with malignant disease had 122 hospital admissions because of fever and neutropenia. All patients had a serum CRP obtained 8 to 24 hours after the onset of fever as part of their initial evaluation. There was a borderline correlation between serum CRP concentration and temperature at admission (P = 0.06). Patients with fever without an identifiable source had significantly lower CRP concentrations compared with those having focal or microbiologically documented infection (34.9 +/- 6 vs. 70.2 +/- 12 mg/liter; P = 0.0005). Twelve patients had positive blood cultures, 5 of which were coagulase-negative staphylococci considered to be central venous catheter-related infection or colonization. CRP concentrations were significantly lower in these 5 patients compared with the 7 patients with septicemia caused by other organisms (21 +/- 9 vs. 113 +/- 23 mg/liter; P = 0.01). In distinguishing between septicemic and nonsepticemic children, serum CRP was found to have excellent sensitivity and negative predictive value at concentration limits of 20, 50 and 100 mg/liter. However, both specificity and positive predictive value were low at these respective levels, thus limiting the overall utility of serum CRP in the initial empiric management of the febrile, neutropenic child with cancer.

Adolescent↗
PubMed1992

Design and evaluation of a sensory feedback system that provides grasping pressure in a myoelectric hand.

Providing accurate sensory information to the individual with a myoelectric limb is of great importance for improving device use in a wide variety of tasks. A number of feedback systems presently being investigated rely on either vibrotactile or electrotactile skin stimulation, which does not provide sensory patterns similar to those in a natural grasping hand. A prototype system was developed to enhance sensory information transfer by using a technique in which the feedback modality (pressure) was the same as the grasping pressure. The present study compared the developed system (pressure) with vibrotactile feedback, vision, and compounds of these three modes. It was found that the pressure-pressure concept reduced grasping pressure replication errors and error variability.

Adult↗
PubMed1991

The yield of routine chest radiography in children with cancer hospitalized for fever and neutropenia.

A routine admission chest radiograph (CXR) in pediatric patients with cancer who are admitted to the hospital for fever and neutropenia has been advised because the signs and symptoms of pneumonia may be absent. The authors studied 131 consecutive patient admissions for fever and neutropenia to evaluate the diagnostic yield of routine CXR. All patients had a complete history, physical examination, complete blood count, blood culture, urinalysis, urine culture, and CXR. Patients routinely started ceftazidime monotherapy. Results of the CXR were correlated with the presence or absence of signs and symptoms of respiratory disease. Of 128 CXR results, 26 (20%) were abnormal (13 with known malignant disease, 2 with atelectasis, 3 with peribronchial cuffing, and 8 with pneumonia [6%]). Three patients with pneumonia were asymptomatic. Therefore, only 3 of 128 patients (2.3%) had pneumonia on CXR not suspected by physical examination. None would have had initial therapy modified based on the CXR finding alone. The authors concluded that the incidence of pneumonia in a child with fever and neutropenia is low and that routine CXR at diagnostic evaluation is unnecessary in the asymptomatic ambulatory patient.

Adolescent↗
PubMed1991

Cytogenetic features of childhood acute lymphoblastic leukemia. A concordance study and a Pediatric Oncology Group study.

Cytogenetic analysis yields important objective information that has been shown to correlate with both patient response to therapeutic intervention and patient survival. Bone marrow samples are submitted to a common reference laboratory for cytogenetic analysis from children with newly diagnosed acute lymphoblastic leukemia (ALL) registered on frontline Pediatric Oncology Group (POG) therapeutic studies (classification 8600 series). A portion of the sample from the Texas Children's Hospital (Houston, TX) a POG affiliate, was also submitted to a local cytogenetics laboratory for analysis. This study retrospectively compares karyotypic data and methods from the Laboratory of Medical Genetics, University of Alabama at Birmingham (reference laboratory) with those of the Kleberg Cytogenetics Laboratory at the Baylor College of Medicine (local laboratory) over a 35-month period to evaluate the effect of differences in specimen procurement, handling, and laboratory methodology on yield of cytogenetic information. Each laboratory was able to identify clonal abnormalities in 72% of cases examined during the last year of the study. When these data were combined, the overall detection rate of clonal abnormalities was 87.5%. Utilizing the same bone marrow aspirate from 73 children, this study demonstrates that cytogenetic methodology significantly affects the yield of identifiable clonal abnormalities, while variables such as overnight shipping have no discernable effect. This study also supports the contention that central laboratory testing effectively yields information critical to ongoing large-scale research endeavors.

Adolescent↗
PubMed1990

Typhlitis. An 18-year experience and postmortem review.

A review of pediatric autopsy results at the Texas Children's Hospital, Baylor College of Medicine from 1970 through 1987 was conducted. Thirty-three cases of typhlitis were identified in patients with acute leukemia and two cases each in patients with lymphoblastic lymphoma and aplastic anemia. Patients ranged in age from 10 months to 17 years. Fifty-seven percent were male and 43% were female. All were myelosuppressed. A postmortem incidence rate of 24% was determined for patients with acute leukemia. Common symptoms included abdominal pain and distention in 78% of patients and acute lower gastrointestinal bleeding in 35%. Abdominal radiographs varied in spectrum from a nonspecific bowel gas pattern to frank right colonic pneumatosis intestinalis. Thirty-three patients received chemotherapy within 30 days before onset of abdominal symptoms. All patients were febrile (greater than 38.5 degrees C), and 33 received broad-spectrum antibiotics. Three patients received amphotericin B. Premortem, 84% of organisms cultured from blood were bacterial whereas 16% were fungal. Fungal pathogens accounted for 53% of new microorganisms seen at autopsy. Postmortem examination showed typhlitis in the following anatomic distributions: (1) confined to the cecum; (2) involving the cecum and ileum; (3) involving the cecum, ileum, and ascending colon; or (4) involving the cecum, with sporadic ulcers throughout the intestine. This review includes clinical and postmortem features of typhlitis and current strategies for diagnosis and management.

Adolescent↗
PubMed1990

Pharmacodynamics and pharmacokinetics of epidural ropivacaine in humans.

The purpose of this study was to characterize the pharmacodynamics and pharmacokinetics of three concentrations of the new long-acting amide local anesthetic, ropivacaine, given epidurally in 15 physical status ASA I or II patients for elective lower-extremity orthopedic procedures using a nonrandomized open-label design. Three groups of five patients each received either 0.5%, 0.75%, or 1.0% ropivacaine. Upper and lower levels of analgesia to pinprick were determined at frequent intervals until normal sensation had completely returned. Motor blockade was assessed by use of a modified Bromage scale after each determination of level of analgesia. Fifteen venous blood samples were collected over 12 h after ropivacaine injection. Pharmacokinetic parameters were derived using serum concentration-time data. No significant differences were found between the three groups in terms of onset or recovery of motor and sensory blockade. Median maximum thoracic levels of analgesia achieved were 8, 6, and 5 for the 0.5%, 0.75%, and 1.0% groups, respectively, and occurred at 29 +/- 11, 37 +/- 21, and 30 +/- 9 min. Respective times to two-segment regression were 2.8 +/- 1.0, 3.0 +/- 0.5, and 2.9 +/- 0.6 h. Total durations of sensory blockade were 5.4 +/- 0.7, 6.5 +/- 0.4, and 6.8 +/- 0.8 h, respectively. No statistically significant differences were noted between the three groups in terms of clearance (CL). The mean residence time (MRT) was significantly longer for the 0.5% group when compared with the 1% group. The peak concentration (Cmax) for the 0.5% group was found to be significantly lower than for either the 0.75% or 1% groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Factors affecting perioperative pulmonary function in acute respiratory failure.

To determine the magnitude, duration, and associated factors of perioperative changes in pulmonary function, we retrospectively reviewed the medical records of 145 patients who required preoperative mechanical ventilation for acute respiratory failure before undergoing 200 surgical procedures. Patients were grouped into five pulmonary diagnostic categories: (1) adult respiratory distress syndrome (ARDS) (n = 49); (2) pneumonia (n = 20); (3) atelectasis (n = 65); (4) congestive heart failure (n = 11); and (5) acute ventilatory failure (n = 55). Sixty patients underwent intra-abdominal surgery, 135 patients required surgery on the periphery, and five patients had a thoracotomy. For all patients, PaO2/FIO2 declined significantly from 321 mm Hg (mean) preoperatively to 258 mm Hg intraoperatively, and shunt fraction (Qs/QT) increased from 0.16 to 0.23 without a significant change in PaCO2. The magnitude of the increase in Qs/QT did not differ among pulmonary diagnostic groups. Preoperatively, patients undergoing laparotomy had lower PaO2/FIO2 (278 vs 340) and higher Qs/QT (0.19 vs 0.14) than patients requiring surgery on the periphery. Intraoperatively, Qs/QT increased more during abdominal procedures than during peripheral procedures. Intraoperative hypoxemia (PaO2/FIO2 less than 80 mm Hg) occurred during 13 procedures. Hypoxemic patients had a mean increase in Qs/QT of 0.20 (0.25 preoperatively to 0.45 intraoperatively), and a significant increase in PaCO2 from 38 mm Hg to 45 mm Hg intraoperatively). In general, these patients had ARDS (n = 10), sepsis (n = 10), a laparotomy (n = 9), and intraoperative mechanical ventilation via the Ohio Anesthesia ventilator (n = 8), a commonly used operating room ventilator. Their preoperative peak airway pressure (54 cm H2O) and minute ventilation (20 L/min) requirements exceeded the capabilities of the Ohio Anesthesia ventilator and likely contributed to impaired gas exchange intraoperatively. Within the first several hours postoperatively, PaO2/FIO2 recovered to preoperative levels in all patients, even in those who had severe intraoperative hypoxemia develop and who underwent laparotomy. We conclude that most patients with acute respiratory failure receiving preoperative mechanical ventilation experienced mild-to-moderate deterioration in intraoperative pulmonary oxygen exchange that rapidly returned to preoperative levels after surgery. We recommend that necessary surgery not be postponed by concern that pulmonary function will be worsened by surgery and anesthesia.

Acute Disease↗
PubMed1989

Relationship between human development and disappearance of unusually large von Willebrand factor multimers from plasma.

von Willebrand factor (vWF) multimers were examined in fetal, umbilical cord, and neonatal platelet-poor plasma (PPP) specimens. Sixty-five of 65 (100%) fetal PPP samples aged less than 35 weeks and seven of ten (70%) fetal samples aged greater than 35 weeks had unusually large vWF (ULvWF) multimers. Thirty of 46 (65%) cord PPP samples from neonates ranging in gestational age from 34 to 41 weeks had ULvWF. There was no significant relationship between either gestational age at time of delivery or birth weight and likelihood of finding ULvWF multimers in cord PPP samples. No maternal PPP sample contained ULvWF multimers. Serial heelstick samples from 16 preterm and term neonates were analyzed for 8 weeks. ULvWF multimers disappeared from the PPP of ten of the neonates during this time. The PPP of four neonates had vWF patterns similar to those in normal adult PPP throughout the sampling period. The ULvWF multimeric forms of fetal and neonatal PPP samples were similar to those constitutively released from endothelial cells. They were not as slowly migrating in a very porous 0.5% agarose gel system as the ULvWF multimers released from Weibel-Palade bodies in response to the calcium ionophore A23187. A vWF protomer was present in 97% of fetal samples, 83% of cord blood specimens, and 11% of neonatal heelstick samples, but was not found in any maternal sample. These results indicate that control mechanisms operative in older children and adults to prevent circulation of ULvWF multimers and vWF protomeric forms are normally acquired late in uterine life or during the neonatal period. ULvWF multimers, which are normal components of fetal, most cord, and some neonatal plasma samples, may contribute to in utero and postnatal hemostasis.

Autoradiography↗
PubMed1989

Dose-response relationships of doxacurium chloride in humans during anesthesia with nitrous oxide and fentanyl, enflurane, isoflurane, or halothane.

In a two-part study, the dose-response relationships of doxacurium chloride (BW A938U) were evaluated during general anesthesia maintained with commonly used anesthetic techniques. In part 1, cumulative dose-response methodology was used to establish the ED95 of doxacurium in 36 patients receiving 70% nitrous oxide and fentanyl, or 50% nitrous oxide and either 1.26% enflurane, 0.84% isoflurane, or 0.57% halothane anesthesia. Mechanomyographic response to train-of-four stimulation was used to monitor neuromuscular blockade. The peak effect of doxacurium following each 5 micrograms/kg incremental dose was noted and a log-probit dose-response curve was constructed for each individual patient. The median ED50s were 11 micrograms/kg, 6 micrograms/kg, 8 micrograms/kg, and 8 micrograms/kg for patients receiving fentanyl, enflurane, isoflurane, or halothane anesthesia, respectively. The median ED95s were 24 micrograms/kg, 14 micrograms/kg, 16 micrograms/kg, and 19 micrograms/kg for patients receiving fentanyl, enflurane, isoflurane, and halothane anesthesia, respectively. In part 2, 72 additional patients received a rapid single injection of the ED95 (n = 36) or 2 X ED95 (n = 36) of doxacurium appropriate for the administered anesthetic as estimated from part one of the study. Peak effects of the ED95 given as single injections correlated well with the results in part 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Mivacurium-induced neuromuscular blockade following single bolus doses and with continuous infusion during either balanced or enflurane anesthesia.

Mivacurium chloride (BW B1090U) was administered to 72 patients during their elective surgery. The eight groups (nine subjects per cell) in the 2 x 2 x 2 study design differed in three factors: the size of the mivacurium bolus dose administered, whether or not this dose was followed by an infusion of mivacurium, and in the technique used for the maintenance of anesthesia. Four groups received a single bolus dose of mivacurium, 0.15 mg/kg, and the remaining four groups received mivacurium, 0.25 mg/kg, administered iv in 15 s. Precisely 2 min later, tracheal intubation was attempted. Conditions were judged to be good or excellent on most occasions, but intubation was not possible for two of the patients in the low-dose and one in the high-dose groups. Four groups, two at each bolus dose, received no additional mivacurium: there was a dose-dependent decrease in the rate of spontaneous recovery following the bolus dose. The other subdivision of groups was the use of either barbiturate-nitrous oxide-narcotic (balanced) anesthesia, or enflurane-nitrous oxide anesthesia; the anesthetic technique did not affect the pattern of spontaneous recovery from either bolus dose. Four groups, again two at each bolus dose, subsequently received an infusion of mivacurium, adjusted to depress the twitch response by approximately 95%. Infusion rates averaged 6.0 micrograms.kg-1.min-1 in the groups receiving balanced anesthesia and 4.2 micrograms.kg-1.min-1 for those receiving enflurane anesthesia. Recovery following administration by infusion was slower than that observed following a bolus dose of mivacurium, 0.15 mg/kg but did not differ between the anesthetic groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Perioperative pulmonary function in acute respiratory failure: effect of ventilator type and gas mixture.

Whether maintaining pulmonary nitrogenation and/or a stable ventilatory pattern during surgery would minimize changes in perioperative pulmonary function in two groups of patients with acute respiratory failure (ARF) whose lungs were being mechanically ventilated was examined. Group 1 (n = 39 cases) (inspired oxygen fraction [FIO2] less than or equal to 0.5, minute ventilation less than or equal to 15 l/min, peak inspiratory pressure less than or equal to 50 cmH2O, positive end-expiratory pressure [PEEP] less than or equal to 10 cmH2O) were assigned randomly to one of four intraoperative ventilator-gas mixture (FIO2 approximately 0.5) combinations: 1) Siemens 900C ventilator, N2/O2; 2) Siemens 900C ventilator, N2O/O2; 3) Ohio anesthesia ventilator, N2/O2; or 4) Ohio anesthesia ventilator, N2O/O2. Group 2 (n = 15 cases) (ventilatory requirements exceeding any of those in Group 1) had their lungs ventilated intraoperatively with the Siemens 900C ventilator and a gas mixture determined by their anesthesiologist (FIO2 approximately 0.6-1.0). In patients whose lungs were ventilated with the Ohio N2O/O2 combination, PaO2/FIO2 decreased significantly (P less than 0.05) from 358 +/- 93 mmHg (mean +/- SD) preoperatively to 282 +/- 77 mmHg intraoperatively. The level of PEEP increased significantly from 5 +/- 3 cmH2O preoperatively to 9 +/- 4 cmH2O intraoperatively (P less than 0.05). In patients whose lungs were ventilated with the Ohio N2/O2 combination, PaO2/FIO2 decreased significantly from 270 +/- 86 mmHg preoperatively to 174 +/- 74 mmHg intraoperatively. These variables did not change significantly in patients ventilated with the Siemens ventilator (groups 1 and 2). Pulmonary oxygen gas exchange returned to preoperative values by the first hour postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗