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Biomedical subjects

M M Pollack

Publications and source records attributed to M M Pollack.

At least 19 recordsLinked to original sources
PubMed2001

Long-stay patients in the pediatric intensive care unit.

OBJECTIVE: Length of stay in the pediatric intensive care unit (PICU) is a reflection of patient severity of illness and health status, as well as PICU quality and performance. We determined the clinical profiles and relative resource use of long-stay patients (LSPs) and developed a prediction model to identify LSPs for early quality and cost saving interventions. DESIGN: Nonconcurrent cohort study. SETTING: A total of 16 randomly selected PICUs and 16 volunteer PICUs. PATIENTS: A total of 11,165 consecutive admissions to the 32 PICUs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: LSPs were defined as patients having a length of stay greater than the 95th percentile (>12 days). Logistic regression analysis was used to determine which clinical characteristics, available within the first 24 hrs after admission, were associated with LSPs and to create a predictive algorithm. Overall, LSPs were 4.7% of the population but represented 36.1% of the days of care. Multivariate analysis indicated that the following factors are predictive of long stays: age <12 months, previous ICU admission, emergency admission, no CPR before admission, admission from another ICU or intermediate care unit, chronic care requirements (total parenteral nutrition and tracheostomy), specific diagnoses including acquired cardiac disease, pneumonia, and other respiratory disorders, having never been discharged from the hospital, need for ventilatory support or an intracranial catheter, and a Pediatric Risk of Mortality III score between 10 and 33. The performance of the prediction algorithm in both the training and validation samples for identifying LSPs was good for both discrimination (area under the receiver operating characteristics curve of 0.83 and 0.85, respectively), and calibration (goodness of fit, p = .33 and p = .16, respectively). LSPs comprised from 2.1% to 8.1% of individual ICU patients and occupied from 15.2% to 57.8% of individual ICU bed days. CONCLUSIONS: LSPs have less favorable outcomes and use more resources than non-LSPs. The clinical profile of LSPs includes those who are younger and those that require chronic care devices. A predictive algorithm could help identify patients at high risk of prolonged stays appropriate for specific interventions.

Age Distribution↗
PubMed2000

The impact of prematurity: a perspective of pediatric intensive care units.

OBJECTIVE: To evaluate the relative resource use of pediatric intensive care unit (PICU) patients who had been born prematurely. DESIGN: Nonconcurrent cohort study. SETTING: Consecutive admissions to 16 voluntary PICUs. PATIENTS: A total of 431 formerly premature patients (FPP) and 5,319 nonpremature patients. INTERVENTIONS: None METHODS: Patients with a history of prematurity and a prematurity-related complication or an anatomical deformity were compared for demographic and resource requirements to a group of non-premature patients by a bivariable logistic regression analysis that controlled for age as a co-morbid factor. RESULTS: Compared with other patients, FPP were younger (34.9 +/- 2.2 months vs. 72.4 +/- 1.0 months; p < .001), readmitted to the PICU more often during the same hospitalization (11.1% vs. 5.5%; p < .001), used more chronic technologies (ventilators, gastrostomy tubes, tracheostomy tubes, and parenteral nutrition; 30.3% vs. 5.6%; p < .001), and had longer lengths of stay (5.98 +/-0.59 days vs. 3.56 +/- 0.12 days; p = .004). FPP had significantly higher use of ventilators (45.5% vs. 35.0%; p < .007) and lower use of arterial catheters (27.8% vs. 35.9%, p = .006) and central venous catheters (16.9% vs. 20.9%, p = .026) than nonprematures. The need for other PICU resources, including vasopressors, were similar. CONCLUSIONS: FPP used more chronic and acute care resources than patients who were not prematurely born. Continued improvements in neonatal care will influence change in many aspects of the health care system. This will also affect the delivery of care to the current patient base of the PICU.

Case-Control Studies↗
PubMed2000

Risk assessment and standardized nosocomial infection rate in critically ill children.

OBJECTIVES: To develop and validate a pediatric nosocomial infection risk (PNIR) assessment model, and to compare the daily trends in risk factors between patients with nosocomial infection (cases) and without nosocomial infection (controls) in the pediatric intensive care unit (ICU). DESIGN: Prospective cohort. SETTING: A 16-bed pediatric ICU in an urban, university-affiliated, multidisciplinary, regional referral center. PATIENTS: Patients available for study included consecutive admissions to the unit between May 1, 1992, and April 30, 1993, and between May 9, 1995, and December 11, 1995. Patients from both data collection periods were pooled and randomly divided into training (70%) and validation (30%) samples. MEASUREMENTS AND MAIN RESULTS: In the logistic regression analysis using admission day data, three factors were shown to remain as independent risk factors. Invasive device use, parenteral nutrition, and the interaction between severity of illness-modified Pediatric Risk of Mortality III-24 score and postoperative care were associated with 2, 6, and 1.5 times the risk of developing nosocomial infection, respectively. This PNIR model performed well in both the training and validation samples as indicated by the goodness-of-fit test, which evaluated standardized nosocomial infection rates (observed vs. predicted nosocomial infection rates). The internal validity of the PNIR model was good. In trend analysis, severity of illness and invasive device use appear to have similar trend patterns, during the first week of pediatric ICU stay. There was no difference in any of these risk factors between cases and controls after 7 days of pediatric ICU stay. CONCLUSIONS: The PNIR assessment model incorporates intrinsic factors, such as patient severity of illness, and extrinsic factors contributing to the development of nosocomial infection in this high-risk population. The methodology using intrinsic and extrinsic factors to adjust for nosocomial infections should be taken into consideration when evaluating interhospital comparison of nosocomial infection rates, quality assessment, intervention strategies, and use of treatment modalities.

Child, Preschool↗
PubMed2000

Combining physician's subjective and physiology-based objective mortality risk predictions.

OBJECTIVE: None of the currently available physiology-based mortality risk prediction models incorporate subjective judgements of healthcare professionals, a source of additional information that could improve predictor performance and make such systems more acceptable to healthcare professionals. This study compared the performance of subjective mortality estimates by physicians and nurses with a physiology-based method, the Pediatric Risk of Mortality (PRISM) III. Then, healthcare provider estimates were combined with PRISM III estimates using Bayesian statistics. The performance of the Bayesian model was then compared with the original two predictions. DESIGN: Concurrent cohort study. SETTING: A tertiary pediatric intensive care unit at a university affiliated children's hospital. PATIENTS: Consecutive admissions to the pediatric intensive care unit. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: For each of the 642 consecutive eligible patients, an exact mortality estimate and the degree of certainty (continuous scale from 1 to 5) associated with the estimate was collected from the attending, fellow, resident, and nurse responsible for the patient's care. Bayesian statistics were used to combine the PRISM III and certainty weighted subjective predictions to create a third Bayesian estimate of mortality. PRISM III discriminated survivors from nonsurvivors very well (area under curve [AUC], 0.924) as did the physicians and nurses (AUCs attendings, 0.953; fellows, 0.870; residents, 0.923; nurses, 0.935). Although the AUCs of the healthcare providers were not significantly different from the AUCs of PRISM III, the Bayesian AUCs were higher than both the healthcare providers' AUCs (p < or = .09 for all) and PRISM III AUCs. Similarly, the calibration statistics for the Bayesian estimates were superior to the calibration statistics for both the healthcare providers and PRISM III models. CONCLUSIONS: The results of this study demonstrated that healthcare providers' subjective mortality predictions and PRISM III mortality predictions perform equally well. The Bayesian model that combined provider and PRISM III mortality predictions was more accurate than either provider or PRISM III alone and may be more acceptable to physicians. A methodology using subjective outcome predictions could be more relevant to individual patient decision support.

Adolescent↗
PubMed2000

A comparison of neonatal mortality risk prediction models in very low birth weight infants.

BACKGROUND: Risk-adjusted severity of illness is frequently used in clinical research and quality assessments. Although there are multiple methods designed for neonates, they have been infrequently compared and some have not been assessed in large samples of very low birth weight (VLBW; <1500 g) infants. OBJECTIVES: To test and compare published neonatal mortality prediction models, including Clinical Risk Index for Babies (CRIB), Score for Neonatal Acute Physiology (SNAP), SNAP-Perinatal Extension (SNAP-PE), Neonatal Therapeutic Interventions Scoring System, the National Institute of Child Health and Human Development (NICHD) network model, and other individual admission factors such as birth weight, low Apgar score (<7 at 5 minutes), and small for gestational age status in a cohort of VLBW infants from the Washington, DC area. METHODS: Data were collected on 476 VLBW infants admitted to 8 neonatal intensive care units between October 1994 and February 1997. The calibration (closeness of total observed deaths to the predicted total) of models with published coefficients (SNAP-PE, CRIB, and NICHD) was assessed using the standardized mortality ratio. Discrimination was quantified as the area under the curve (AUC) for the receiver operating characteristic curves. Calibrated models were derived for the current database using logistic regression techniques. Goodness-of-fit of predicted to observed probabilities of death was assessed with the Hosmer-Lemeshow goodness-of-fit test. RESULTS: The calibration of published algorithms applied to our data was poor. The standardized mortality ratios for the NICHD, CRIB, and SNAP-PE models were.65,.56, and.82, respectively. Discrimination of all the models was excellent (range:.863-.930). Surprisingly, birth weight performed much better than in previous analyses, with an AUC of.869. The best models using both 12- and 24-hour postadmission data, significantly outperformed the best model based on birth data only but were not significantly different from each other. The variables in the best model were birth weight, birth weight squared, low 5-minute Apgar score, and SNAP (AUC =.930). CONCLUSION: Published models for severity of illness overpredicted hospital mortality in this set of VLBW infants, indicating a need for frequent recalibration. Discrimination for these severity of illness scores remains excellent. Birth variables should be reevaluated as a method to control for severity of illness in predicting mortality.

Female↗
PubMed1999

Teaching physicians how to break bad news: a 1-day workshop using standardized parents.

OBJECTIVE: To evaluate the effectiveness of a training program using standardized parents (SPs) to improve the performance of pediatric intensive care fellows in communicating bad news to parents. DESIGN: Self-controlled crossover design. SETTING: Tertiary pediatric intensive care unit in a university-affiliated children's hospital. PARTICIPANTS: Seven pediatric intensive care fellows and 4 trained volunteers (2 sets of SPs) participated in the study. METHODS: Two case scenarios of children admitted to the intensive care unit with a near-fatal diagnosis were used for the fellow's interactions with the SPs. The SPs had received 15 hours of training in role playing, performance evaluation, and giving feedback to the physicians. At the end of the first session, SPs provided feedback to the physicians under each of the 5 following categories: communication skills, content issues, support systems, interventions, and parent perceptions. During the second session, the parent meeting was repeated with a new but similar case scenario and a different set of SPs. Both sessions were videotaped, and a rater blinded to the order of the sessions used a weighted scale based on a checklist to score changes in physician performance. RESULTS: The performance by the fellows showed a significant mean (+/-SEM) improvement in scores of 18.1 (+/-5.2) points (P = .007) between the first and the second sessions. Ranking of session scores revealed that physician performance improved significantly during the second session (Wilcoxon signed rank test, P = .002). CONCLUSIONS: To our knowledge this is the first study that demonstrates short-term improvement in physician performance in conveying bad news in a pediatric intensive care setting using SPs in a 1-day workshop.

Adult↗
PubMed1999

Aminophylline in the treatment of fluid overload.

OBJECTIVE: Aminophylline has not been studied as an adjunct diuretic in critically ill children. Our purpose was to evaluate its use in the treatment of fluid overload in these patients. DESIGN: Open, controlled clinical trial. SETTING: Pediatric intensive care unit. PATIENTS: Study subjects ranged from 2-46 months of age, were fluid overloaded, and were receiving a continuous infusion of furosemide (> or =6 mg/kg/day). Patients with hemodynamic instability or liver dysfunction were excluded. INTERVENTIONS: A single dose of aminophylline (6 mg/kg) was given after establishing baseline values. There were no additional diuretics or changes in vasoactive agents during the study. MEASUREMENTS AND MAIN RESULTS: Urine output, creatinine clearance, and sodium and potassium excretion were measured before and after administration of the aminophylline bolus. Heart rate and mean arterial pressure (mm Hg) were recorded hourly. Urine output increased by >80% (p < .01) during the first 2 hrs after administration of the aminophylline bolus and then returned to baseline by 4 to 6 hrs. The change in urine output is consistent with the pharmacokinetics of aminophylline. Heart rate and mean arterial pressure exhibited a change of <10% from baseline. CONCLUSIONS: These results suggest that aminophylline is an effective adjunct to furosemide in increasing diuresis in critically ill children with fluid overload. The increased diuresis can be accomplished without increased risk if drug levels are adequately monitored.

Adjuvants, Pharmaceutic↗
PubMed1999

Prognostication and certainty in the pediatric intensive care unit.

OBJECTIVE: Prognostication is central to developing treatment plans and relaying information to patients, family members, and other health care providers. The degree of confidence or certainty that a health care provider has in his or her mortality risk assessment is also important, because a provider may deliver care differently depending on their assuredness in the assessment. We assessed the performance of nurse and physician mortality risk estimates with and without weighting the estimates with their respective degrees of certainty. METHODS: Subjective mortality risk estimates from critical care attendings (n = 5), critical care fellows (n = 9), pediatric residents (n = 34), and nurses (n = 52) were prospectively collected on at least 94% of 642 eligible, consecutive admissions to a tertiary pediatric intensive care unit (PICU). A measure of certainty (continuous scale from 0 to 5) accompanied each mortality estimate. Estimates were evaluated with 2 x 2 outcome probabilities, the kappa statistic, the area under the receiver operating characteristics curve, and the Hosmer and Lemeshow goodness-of-fit chi(2) statistic. The estimates were then reevaluated after weighting predictions by their respective degree of certainty. RESULTS: Overall, there was a significant difference in the predictive accuracy between groups. The mean mortality predictions from the attendings (6.09%) more closely approximated the true mortality rate (36 deaths, 5.61%) whereas fellows (7.87%), residents (10.00%), and nurses (16.29%) overestimated the mean overall PICU mortality. Attendings were more certain of their predictions (4.27) than the fellows (4.01), nurses (3.79), and residents (3.75). All groups discriminated well (area under receiver operating characteristics curve range, 0.86-0.93). Only PICU attendings and fellows did not significantly differ from ideal calibration (chi(2)). When mortality predictions were weighted with their respective certainties, their performance improved. CONCLUSIONS: The level of medical training correlated with the provider's ability to predict mortality risk. The higher the level of certainty associated with the mortality prediction, the more accurate the prediction; however, high levels of certainty did not guarantee accurate predictions. Measures of certainty should be considered when assessing the performance of mortality risk estimates or other subjective outcome predictions.

Analysis of Variance↗
PubMed1998

Hemodynamic effects of high-frequency oscillatory ventilation in children.

The purpose of this study was to evaluate the acute hemodynamic effects of transitioning a patient from conventional mechanical ventilation (CMV) to high-frequency oscillatory ventilation (HFOV). Our hypothesis was that hemodynamic status would not be adversely affected by such a change. Ten pediatric patients with acute hypoxemic respiratory failure and a thermodilution pulmonary arterial catheter in place were prospectively evaluated on the transition from CMV to HFOV. Hemodynamic and respiratory data were obtained before and within 1 hour of transition to HFOV with a "high-volume" ventilation strategy. On CMV, the mean oxygenation index of the patients was 18+/-4. Despite increases in mean airway pressure and decreases in mean arterial pressure and systemic vascular resistance on HFOV, there was no change in pulmonary circulation variables, cardiac index, or oxygen delivery. We concluded that in pediatric patients with acute respiratory failure and unstable cardiovascular status, the transition from CMV to HFOV was not accompanied by a decrease in cardiac function or oxygen delivery.

Acute Disease↗
PubMed1998

Decision support issues using a physiology based score.

OBJECTIVE: As physiology based assessments of mortality risk become more accurate, their potential utility in clinical decision support and resource rationing decisions increases. Before these prediction models can be used, however, their performance must be statistically evaluated and interpreted in a clinical context. We examine the issues of confidence intervals (as estimates of survival ranges) and confidence levels (as estimates of clinical certainty) by applying Pediatric Risk of Mortality III (PRISM III) in two scenarios: (1) survival prediction for individual patients and (2) resource rationing. DESIGN: A non-concurrent cohort study. SETTING: 32 pediatric intensive care units (PICUs). PATIENTS: 10608 consecutive patients (571 deaths). INTERVENTIONS: None. MEASUREMENTS AND RESULTS: For the individual patient application, we investigated the observed survival rates for patients with low survival predictions and the confidence intervals associated with these predictions. For the resource rationing application, we investigated the maximum error rate of a policy which would limit therapy for patients with scores exceeding a very high threshold. For both applications, we also investigated how the confidence intervals change as the confidence levels change. The observed survival in the PRISM III groups >28, >35, and >42 were 6.3, 5.3, and 0%, with 95% upper confidence interval bounds of 10.5, 13.0, and 13.3%, respectively. Changing the confidence level altered the survival range by more than 300% in the highest risk group, indicating the importance of clinical certainty provisions in prognostic estimates. The maximum error rates for resource allocation decisions were low (e. g., 29 per 100000 at a 95% certainty level), equivalent to many of the risks of daily living. Changes in confidence level had relatively little effect on this result. CONCLUSIONS: Predictions for an individual patient's risk of death with a high PRISM score are statistically not precise by virtue of the small number of patients in these groups and the resulting wide confidence intervals. Clinical certainty (confidence level) issues substantially influence outcome ranges for individual patients, directly affecting the utility of scores for individual patient use. However, sample sizes are sufficient for rationing decisions for many groups with higher certainty levels. Before there can be widespread acceptance of this type of decision support, physicians and families must confront what they believe is adequate certainty.

Algorithms↗
PubMed1998

Length of stay and efficiency in pediatric intensive care units.

OBJECTIVE: Assessment of pediatric intensive care unit (PICU) efficiency with a length of stay prediction model and validation of this assessment by an efficiency measure based on daily use of intensive care unit-specific therapies. DESIGN: Inception cohort study of data acquired between 1989 and 1994. SETTING: Thirty-two PICUs, 16 selected randomly and 16 volunteering. SUBJECTS: Consecutive admissions of 10,658 patients (466 deaths) who stayed at least 2 hours and up to 12 days in the PICU. MEASUREMENTS: Length of stay and its prediction from a model with admission day data (PRISM III-24, diagnostic factors, mechanical ventilation). For validation 11 PICUs recorded each patient's "efficient" days, that is, days when at least one PICU-specific therapy was given. PICU efficiency was computed as either the ratio of the observed efficient days or the days accounted for by the predictor variables to the total care days, and the agreement was assessed by Spearman's rank correlation analysis. RESULTS: The total care days provided by each PICU (n = 32) were well predicted by the length of stay model (r = 0.946). The agreement in 11 validation PICUs between therapy-based efficiency (range 0.30 to 0.67) and predictor-based efficiency (range 0.31 to 0.63) was excellent (rank correlation r = 0.936, p < 0.0001). CONCLUSION: PICU efficiency comparisons with either method are nearly equivalent. Predictor-based efficiency has the advantage that it can be computed from admission day data only.

Cohort Studies↗
PubMed1998

Pediatric risk of admission (PRISA): a measure of severity of illness for assessing the risk of hospitalization from the emergency department.

STUDY OBJECTIVE: The development and validation of a pediatric emergency department severity of illness assessment method, using hospital admission as the primary outcome. METHODS: A random sample of 25% of ED charts from 4 consecutive months in a university-affiliated pediatric hospital was reviewed, after exclusion of children with minor injuries and children triaged to the nonurgent clinic. Sampled data included components of the medical history, physical findings, physiologic variables, diagnoses, and ED therapies. Univariate and multivariate logistic regression analyses, with bootstrapping validation, were performed to develop a bias-corrected model estimating the probability of hospital admission. RESULTS: Of the 2,683 ED patients whose records were reviewed, 643 (24%) were admitted to the hospital. The final model, which yielded a Pediatric Risk of Admission (PRISA) score, included the following: 3 components of the medical history, 3 chronic disease factors, 9 physiologic variables, 2 therapies, and 4 interaction terms. Overall, the number of hospital admissions was well predicted in both the 80% development and 20% validation samples. In the former, 514 admissions were predicted and 514 were observed; in the latter, 126.9 admissions were predicted and 129 were observed. The Hosmer-Lemeshow goodness-of-fit test demonstrated good agreement between observed and expected admissions in consecutive deciles of admission probability; total chi2 was 10.49 (P=.233) for the development sample and 11.85 (P=.222) for the validation sample. The areas under the receiver operating characteristic curves (+/-SE) were .86+/-.011 and .825+/-.024, respectively. As the risk of hospital admission increased, the proportions of patients using unique hospital-based resources and using ICU resources increased, and the proportion of patients dying increased. CONCLUSION: The probability of admission to the hospital can reliably be estimated from data available during the pediatric ED stay. Applications for this method include studies of quality and efficiency of care and measurements of severity of illness.

Adolescent↗
PubMed1998

Decomplexification in critical illness and injury: relationship between heart rate variability, severity of illness, and outcome.

OBJECTIVES: To determine if decomplexification of heart rate dynamics occurs in critically ill and injured pediatric patients. We hypothesized that heart rate power spectra, a measure of heart rate dynamics, would inversely correlate with measures of severity of illness and outcome. DESIGN: A prospective clinical study. SETTING: A 12-bed pediatric intensive care unit (ICU) in a tertiary care children's hospital. PATIENTS: One hundred thirty-five consecutive pediatric ICU admissions. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We compared heart rate power spectra with the Pediatric Risk of Mortality (PRISM) score, the Pediatric Cerebral Performance Category (PCPC), and the Pediatric Overall Performance Category (POPC). We found significant negative correlations between minimum low-frequency and high-frequency heart rate power spectral values recorded during ICU stay and the maximum PRISM score (log low-frequency heart rate power vs. PRISM, r2 = .293, p < .001; and log high-frequency heart rate power vs. PRISM, r2 = .243, p < .001) and outcome at ICU discharge (log low-frequency heart rate power vs. POPC or PCPC, r2 = .429, p < .001; and log high-frequency heart rate power vs. POPC or PCPC, r2 = .271, p < .001). CONCLUSIONS: Our data support the hypothesis that measures of heart rate power spectra are inversely related and negatively correlated to severity of illness and outcome in critically ill and injured children. The phenomenon of decomplexification of physiologic dynamics may have important clinical implications in critical illness and injury.

Adolescent↗
PubMed1998

Increased apnea threshold in a pediatric patient with suspected brain death.

OBJECTIVE: To evaluate the current standards for apnea testing in the evaluation of brain death in children. DESIGN: Case report. SETTING: A tertiary pediatric intensive care unit (ICU). PATIENTS: A single patient admitted to the ICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A formal brain death examination was performed on a 4-yr-old male with a diagnosis of acute pilocytic astrocytoma and global cerebral hypoxic ischemic damage secondary to a cardiorespiratory arrest. The patient fulfilled all criteria for brain death, except the apnea test. An apnea test was performed for 9 mins 23 secs, at which time, spontaneous respiratory effort was noted. The respiratory efforts were initiated with a pH of 7.08 and a PaCO2 of 91 torr (12.1 kPa). CONCLUSION: This case report suggests that current guidelines for apnea testing may lead to erroneous evaluation of medullary-respiratory drive.

Apnea↗