Jason W. Custer

Diagnostic errors in the intensive care unit: a systematic review of autopsy studies

Context Misdiagnoses may be an underappreciated cause of preventable morbidity and mortality in the intensive care unit (ICU). Their prevalence, nature, and impact remain largely unknown. Objectives To determine whether potentially fatal ICU misdiagnoses would be more common than in the general inpatient population (∼5%), and would involve more infections or vascular events. Data sources Systematic review of studies identified by electronic (MEDLINE, etc.) and manual searches (references in eligible articles) without language restriction (1966 through 2011). Study selection and data abstraction Observational studies examining autopsy-confirmed diagnostic errors in the adult ICU were included. Studies analysing misdiagnosis of one specific disease were excluded. Study results (autopsy rate, misdiagnosis prevalence, Goldman error class, diseases misdiagnosed) were abstracted and descriptive statistics calculated. We modelled the prevalence of Class I (potentially lethal) misdiagnoses as a non-linear function of the autopsy rate. Results Of 276 screened abstracts, 31 studies describing 5863 autopsies (median rate 43%) were analysed. The prevalence of misdiagnoses ranged from 5.5%–100% with 28% of autopsies reporting at least one misdiagnosis and 8% identifying a Class I diagnostic error. The projected prevalence of Class I misdiagnoses for a hypothetical autopsy rate of 100% was 6.3% (95% CI 4.0% to 7.5%). Vascular events and infections were the leading lethal misdiagnoses (41% each). The most common individual Class I misdiagnoses were PE, MI, pneumonia, and aspergillosis. Conclusions Our data suggest that as many as 40 500 adult patients in an ICU in USA may die with an ICU misdiagnoses annually. Despite this, diagnostic errors receive relatively little attention and research funding. Future studies should seek to prospectively measure the prevalence and impact of diagnostic errors and potential strategies to reduce them.

A multicenter outcomes analysis of children with severe viral respiratory infection due to human metapneumovirus.

Objective: To investigate the impact of human metapneumovirus on morbidity and mortality outcomes in children with severe viral respiratory infection. Design: Retrospective cohort study. Setting: ICU, either PICU or cardiac ICU, at three urban academic tertiary care children’s hospitals. Patients: All patients admitted to an ICU with laboratory-confirmed human metapneumovirus infection between January 2010 and June 2011. Interventions: We captured demographic and clinical data and analyzed associated morbidity and mortality outcomes. Measurements and Main Results: There were 111 patients with laboratory-confirmed human metapneumovirus admitted to an ICU at one of the three participating institutions during the period of study. The median hospital length of stay was 7 days (interquartile range 4–18 days) and median ICU length of stay was 4 days (interquartile range 1–10 days). Ten patients (9%) did not survive to discharge. Predisposing factors associated with increased mortality included female gender (p = 0.002), presence of a chronic medical condition (p = 0.04), and hospital acquisition of human metapneumovirus infection (p = 0.006). Adjusting for female gender, chronic medical conditions, hospital acquisition of infection and severity of illness score, logistic regression analysis demonstrated that female gender, hospital acquisition of infection, and chronic medical conditions each independently increased the odds of mortality (odds ratios 14.8, 10.7, and 12.7, respectively). Conclusions: Analysis of our results suggests that there is substantial morbidity and mortality associated with severe viral respiratory infection due to human metapneumovirus in children. Female gender, hospital acquisition of human metapneumovirus infection, and presence of chronic medical conditions each independently increases mortality. The burden of illness from human metapneumovirus on the ICU in terms of resource utilization may be considerable.

Redistribution of pulmonary blood flow impacts thermodilution-based extravascular lung water measurements in a model of acute lung injury

Background:Studies using transthoracic thermodilution have demonstrated increased extravascular lung water (EVLW) measurements attributed to progression of edema and flooding during sepsis and acute lung injury. The authors hypothesized that redistribution of pulmonary blood flow can cause increased apparent EVLW secondary to increased perfusion of thermally silent tissue, not increased lung edema. Methods:Anesthetized, mechanically ventilated canines were instrumented with PiCCO® (Pulsion Medical, Munich, Germany) catheters and underwent lung injury by repetitive saline lavage. Hemodynamic and respiratory physiologic data were recorded. After stabilized lung injury, endotoxin was administered to inactivate hypoxic pulmonary vasoconstriction. Computed tomographic imaging was performed to quantify in vivo lung volume, total tissue (fluid) and air content, and regional distribution of blood flow. Results:Lavage injury caused an increase in airway pressures and decreased arterial oxygen content with minimal hemodynamic effects. EVLW and shunt fraction increased after injury and then markedly after endotoxin administration. Computed tomographic measurements quantified an endotoxin-induced increase in pulmonary blood flow to poorly aerated regions with no change in total lung tissue volume. Conclusions:The abrupt increase in EVLW and shunt fraction after endotoxin administration is consistent with inactivation of hypoxic pulmonary vasoconstriction and increased perfusion to already flooded lung regions that were previously thermally silent. Computed tomographic studies further demonstrate in vivo alterations in regional blood flow (but not lung water) and account for these alterations in shunt fraction and EVLW.

A qualitative study of expert and team cognition on complex patients in the pediatric intensive care unit.

Objectives: To understand expert and team cognition of complex patients in the pediatric intensive care unit through the use of cognitive task analysis. Design: Qualitative study with semistructured interviews. Setting: Academic medical center pediatric intensive care unit. Participants: Physicians, nurses, and nurse practitioners. Interventions: None. Measurements and Main Results: Semistructured interviews were conducted with members of the critical care team involved with the care of seven complex patients. Interviews were transcribed and themes were identified based on grounded theory and further divided into categories. A focus group of critical care team members further refined and validated the findings. From the interviews, 177 verbal fragments were sorted into 11 themes. Four broad thematic categories were identified and a cognitive framework for the care of complex patients was formulated. We found that at the center of this framework, critical care teams attempt to create and share mental models of their patients. These mental models serve as the framework for delivery of longitudinal care across handovers and shift changes. The analysis revealed that this process is limited by a number of factors such that team members utilize a variety of techniques to overcome these limitations and develop more complete and shared mental models. Conclusions: An inadequately developed or inadequately shared mental model is a substantial cognitive limitation for expert and team cognition in the complex environment of the pediatric intensive care unit. Providers utilize techniques that may avoid or decrease the variable interpretations of patient condition that would otherwise impair mental model formation and sharing. Future studies should be designed to enhance mental model formation and communication in the pediatric intensive care unit and other environments that deal with complex patients.

Diagnostic errors in the pediatric and neonatal ICU: A systematic review

Objective: Diagnostic errors lead to preventable hospital morbidity and mortality. ICU patients may be at particularly high risk for misdiagnosis. Little is known about misdiagnosis in pediatrics, including PICU and neonatal ICU. We sought to assess diagnostic errors in PICU and neonatal ICU settings by systematic review. Data Sources: We searched PubMed, Embase, CINAHL, and Cochrane. Study Selection: We identified observational studies reporting autopsy-confirmed diagnostic errors in PICU or neonatal ICU using standard Goldman criteria. Data Extraction: We abstracted patient characteristics, diagnostic error description, rates and error classes using standard Goldman criteria for autopsy misdiagnoses and calculated descriptive statistics. Data Synthesis: We screened 329 citations, examined 79 full-text articles, and included 13 studies (seven PICU; six neonatal ICU). The PICU studies examined a total of 1,063 deaths and 498 autopsies. Neonatal ICU studies examined a total of 2,124 neonatal deaths and 1,259 autopsies. Major diagnostic errors were found in 19.6% of autopsied PICU and neonatal ICU deaths (class I, 4.5%; class II, 15.1%). Class I (potentially lethal) misdiagnoses in the PICU (43% infections, 37% vascular) and neonatal ICU (62% infections, 21% congenital/metabolic) differed slightly. Although missed infections were most common in both settings, missed vascular events were more common in the PICU and missed congenital conditions in the neonatal ICU. Conclusion: Diagnostic errors in PICU/neonatal ICU populations are most commonly due to infection. Further research is needed to better quantify pediatric intensive care–related misdiagnosis and to define potential strategies to reduce their frequency or mitigate misdiagnosis-related harm.

ABC-SBAR training improves simulated critical patient hand-off by pediatric interns.

Objectives This study was done to assess whether a modified “ABC-SBAR” mnemonic (airway, breathing, circulation followed by situation, background, assessment, and recommendation) improves hand-offs by pediatric interns in a simulated critical patient scenario. Methods Each of 26 interns reviewed a scenario involving a decompensating pediatric patient and gave a simulated hand-off to a responder. They received a didactic session on ABC-SBAR, then performed a second hand-off using another scenario. Two blinded reviewers assessed 52 video-recorded hand-offs for inclusion, order, and elapsed time to essential hand-off information using a scoring tool. Results Mean score of hand-offs increased after ABC-SBAR training (preintervention: 3.1/10 vs postintervention: 7.8/10, P < 0.001). In hand-offs after ABC-SBAR training, the reason for the emergency call was more often prioritized before background information (preintervention: 4% vs postintervention: 81%, P < 0.001) and stated earlier (elapsed time preintervention: 19 seconds vs postintervention: 7 seconds, P < 0.001). Hand-offs including an airway or breathing assessment increased after training (preintervention: 35% vs postintervention: 85%, P = 0.001), and this information was also stated earlier (preintervention: 25 seconds vs postintervention: 5 seconds, P < 0.001). Total hand-off duration was increased (preintervention: 29 seconds vs postintervention: 36 seconds, P = 0.004). Conclusions Unstructured hand-off by interns in a simulated patient emergency emphasizes background information, leaving essential information (such as reason for the call and ABCs) delayed or omitted. ABC-SBAR was associated with improved inclusion and timeliness of essential information in simulated critical patient hand-offs by pediatric interns; however, hand-off duration was increased. Further studies are needed to elucidate optimal hand-off in an emergency situation.

real-time forecasting of pediatric intensive care unit length of stay using computerized provider orders

Objective:To develop a model to produce real-time, updated forecasts of patients’ intensive care unit length of stay using naturally generated provider orders. The model was designed to be integrated within a computerized decision support system to improve patient flow management. Design:Retrospective cohort study. Setting:Twenty-six bed pediatric intensive care unit within an urban, academic children’s hospital using a computerized order entry system. Patients:A total of 2,178 consecutive pediatric intensive care unit admissions during a 16-month time period. Measurements and Main Results:We obtained unit length of stay measurements, time-stamped provider orders, age, admission source, and readmission status. A joint discrete-time logistic regression model was developed to produce probabilistic length of stay forecasts from continuously updated provider orders. Accuracy was assessed by comparing forecasted expected discharge time with observed discharge time, rank probability scoring, and calibration curves. Cross-validation procedures were conducted. The distribution of length of stay was heavily right-skewed with a mean of 3.5 days (95% confidence interval 0.3–19.1). Provider orders were predictive of length of stay in real-time accurately forecasting discharge within a 12-hr window: 46% for patients within 1 day of discharge, 34% for patients within 2 days of discharge, and 27% for patients within 3 days of discharge. The forecast model incorporating predictive orders demonstrated significant improvements in accuracy compared with forecasts based solely on empirical and temporal information. Seventeen predictive orders were found, grouped by medication, ventilation, laboratory, diet, activity, foreign body, and extracorporeal membrane oxygenation. Conclusions:Provider orders reflect dynamic changes in patients’ conditions, making them useful for real-time length of stay prediction and patient flow management. Patients’ length of stay represent a major source of variability in intensive care unit resource utilization and if accurately predicted and communicated, may lead to proactive bed management with more efficient patient flow.

Total and Regional Lung Volume changes during High-Frequency Oscillatory Ventilation (HFOV) of the normal lung

The effect of high-frequency oscillatory ventilation (HFOV) settings on the distribution of lung volume (V(L)) with changes in mean airway pressure (Paw), frequency (f(R)) and tidal volume (V(T)) remains controversial. We used computer tomographic (CT) imaging to quantify the distribution of V(L) during HFOV compared to static continuous positive airway pressure (CPAP). In anesthetized, supine canines, CT imaging of the entire lung was performed during CPAP and HFOV at Paw of 5, 12.5 and 20 cm H(2)O, f(R)=5, 10, 15 Hz. We found small, statistically significant decreases compared with CPAP in total and regional V(L) during HFOV that were greatest at lower f(R) and Paw. Apex and base sub-volumes underwent changes comparable to the lung overall. Increases in f(R) were accompanied by increases in Pa(O)(2). These finding provide additional insight into the impact of HFOV settings on the distribution of V(L) and suggest that there is low risk of occult regional over-distention during HFOV in normal lungs.

A multicenter outcomes analysis of children with severe rhino/enteroviral respiratory infection.

Objectives: To investigate the impact of human rhino/enteroviruses on morbidity and mortality outcomes in children with severe viral respiratory infection. Design: Retrospective cohort study. Setting: The ICU, either PICU or cardiac ICU, at three urban academic tertiary-care children’s hospitals. Patients: All patients with laboratory-confirmed human rhino/enteroviruses infection between January 2010 and June 2011. Interventions: We captured demographic and clinical data and analyzed associated morbidity and mortality outcomes. Measurements and Main Results: There were 519 patients included in our analysis. The median patient age was 2.7 years. The median hospital and ICU lengths of stay were 4 days and 2 days, respectively. Thirty-four percent of patients had a history of asthma, and 25% of patients had a chronic medical condition other than asthma. Thirty-two percent of patients required mechanical ventilation. Eleven patients (2.1%) did not survive to hospital discharge. The rate of viral coinfection was 12.5% and was not associated with mortality. Predisposing factors associated with increased mortality included immunocompromised state (p < 0.001), ICU admission severity of illness score (p < 0.001), and bacterial coinfection (p = 0.003). Conclusions: There is substantial morbidity associated with severe respiratory infection due to human rhino/enteroviruses in children. Mortality was less severe than reported in other respiratory viruses such as influenza and respiratory syncytial virus. The burden of illness from human rhino/enteroviruses in the ICU in terms of resource utilization may be considerable.

High-Flow Nasal Cannula Utilization in Pediatric Critical Care.

BACKGROUND: High-flow nasal cannula (HFNC) is increasingly utilized in pediatrics, delivering humidified air and oxygen for respiratory conditions causing hypoxia and distress. In the neonatal ICU, it has been associated with better tolerance, lower complications, and lower cost. Few data exist regarding indications for use and the epidemiology of disease/pathology that warrants HFNC in the pediatric ICU. METHODS: This study is a retrospective cohort study of patients admitted to a tertiary childrens hospital pediatric ICU and placed on HFNC from October 1, 2011 to October 31, 2013. Descriptive statistics were used to describe demographics and utilization data. t test comparisons were used for comparison data. RESULTS: Over the enrollment study period, 620 subjects with HFNC were managed, which represented 27% of total ICU admissions. The average age was 3.74 y (range 0–18.1 y), and subjects were 44% female and 65% African American. Reported primary indications for the utilization of HFNC were status asthmaticus (24%), status asthmaticus with pneumonia (17%), and bronchiolitis (16%). Of the subjects admitted with a primary diagnosis of status asthmaticus, 41% required management with terbutaline. Respiratory viral infections were detected by polymerase chain reaction in 334 subjects managed with HFNC (53.8%) and included 260 subjects testing positive for rhinovirus/enterovirus. When compared with all other respiratory viral illness, subjects with rhinovirus/enterovirus required a higher peak flow (14.9 L vs 13.1 L, P = .01); however, this was an older population, and peak oxygen concentration did not differ between the 2 groups (49.8% vs 47.1%, P = .25). HFNC was used as postextubation support in 16% of the subjects. Of the 63 subjects with congenital heart disease, 92% of the utilization was postextubation. CONCLUSIONS: HFNC was utilized in 27% of all pediatric ICU admissions for a wide range of indications. Development of protocols for the initiation, escalation, and weaning of HFNC would optimize the utilization.