David J. Wallace

Prophylactic red-cell transfusions in pregnant patients with sickle cell disease. A randomized cooperative study.

Prophylactic blood transfusion has come to be regarded as necessary in the treatment of patients with sickle cell disease during pregnancy. Because of the risks associated with blood products and reports of successful outcomes without the use of blood transfusion, we conducted a prospective randomized controlled study of this issue. Seventy-two pregnant patients with sickle cell anemia were randomly assigned to one of two treatment groups: 36 received prophylactic transfusions of frozen red cells, and 36 received red-cell transfusions only for medical or obstetric emergencies. Twenty-eight patients with sickle cell anemia who did not qualify for randomization (mainly because they had other medical disorders), 66 with sickle cell-hemoglobin C disease, and 23 with sickle cell-beta-thalassemia were also followed and received transfusions only for emergencies. There was no significant difference in perinatal outcome between the offspring of mothers with sickle cell disease who were assigned to treatment with prophylactic transfusions and those who were not (15 vs. 5 percent). The occurrence of a perinatal death in a previous pregnancy and the presence of twins in the present pregnancy were two major risk factors for an unfavorable outcome; when they were present, perinatal mortality was 50 percent. Perinatal mortality was somewhat higher in the two groups that were randomized than in the three groups that were not. Prophylactic transfusion significantly reduced the incidence of painful crises of sickle cell disease (P less than 0.01) and substantially reduced the cumulative incidence of other complications of this disorder (P = 0.07). Other medical and obstetric complications occurred with nearly equal frequency in the two randomized groups. Increases in costs, the number of hospitalizations, and the risk of alloimmunization were disadvantages of prophylactic transfusion. We conclude that the omission of prophylactic red-cell transfusion will not harm pregnant patients with sickle cell disease or their offspring.

Nighttime Intensivist Staffing and Mortality among Critically Ill Patients

BACKGROUND Hospitals are increasingly adopting 24-hour intensivist physician staffing as a strategy to improve intensive care unit (ICU) outcomes. However, the degree to which nighttime intensivists are associated with improvements in the quality of ICU care is unknown. METHODS We conducted a retrospective cohort study involving ICUs that participated in the Acute Physiology and Chronic Health Evaluation (APACHE) clinical information system from 2009 through 2010, linking a survey of ICU staffing practices with patient-level outcomes data from adult ICU admissions. Multivariate models were used to assess the relationship between nighttime intensivist staffing and in-hospital mortality among ICU patients, with adjustment for daytime intensivist staffing, severity of illness, and case mix. We conducted a confirmatory analysis in a second, population-based cohort of hospitals in Pennsylvania from which less detailed data were available. RESULTS The analysis with the use of the APACHE database included 65,752 patients admitted to 49 ICUs in 25 hospitals. In ICUs with low-intensity daytime staffing, nighttime intensivist staffing was associated with a reduction in risk-adjusted in-hospital mortality (adjusted odds ratio for death, 0.62; P=0.04). Among ICUs with high-intensity daytime staffing, nighttime intensivist staffing conferred no benefit with respect to risk-adjusted in-hospital mortality (odds ratio, 1.08; P=0.78). In the verification cohort, there was a similar relationship among daytime staffing, nighttime staffing, and in-hospital mortality. The interaction between nighttime staffing and daytime staffing was not significant (P=0.18), yet the direction of the findings were similar to those in the APACHE cohort. CONCLUSIONS The addition of nighttime intensivist staffing to a low-intensity daytime staffing model was associated with reduced mortality. However, a reduction in mortality was not seen in ICUs with high-intensity daytime staffing. (Funded by the National Heart, Lung, and Blood Institute.).

The utility of base deficit and arterial lactate in differentiating major from minor injury in trauma patients with normal vital signs

OBJECTIVES Early recognition and treatment of hemorrhagic shock after trauma limits multi-organ failure and mortality. Traditional vital signs (VS) although specific are not highly sensitive for hemorrhage detection. Metabolic parameters such as lactate and base deficit (BD) are highly sensitive indicators of blood loss by measuring tissue perfusion. Does adding information from BD and lactate to traditional VS improve the identification of trauma patients with major injuries? METHODS We conducted a retrospective study of a prospectively collected database at a Level I trauma center from January 2003 to September 2005. Patients >13 years, suspected of having significant injury by mechanism, were included. Abnormal VS were defined by heart rate >100 beats/min or systolic blood pressure <90 mmHg. Metabolic parameters from initial arterial blood gas were measured in all patients, abnormal defined by BD >-2.0 mMol/L or lactate >2.2 mMol/L. Our outcome variable, major injury, was defined as any trauma patient who received a blood transfusion, or dropped their hematocrit >10 points in the first 24 h, or had an Injury Severity Score (ISS) >15. RESULTS 1435 patients were enrolled, 242 (17%) had major injuries. Abnormal VS alone had a sensitivity of 40.9% (95% CI, 34.7-47.1%) for identifying major injury patients. When abnormal metabolic parameters were added, major injury detection increased significantly to a sensitivity of 76.4% (95% CI, 71.1-81.8%). CONCLUSIONS The addition of BD and lactate to triage vital signs increases the ability to distinguish major from minor injury.

Inferior Vena Cava Percentage Collapse During Respiration Is Affected by the Sampling Location: An Ultrasound Study in Healthy Volunteers

OBJECTIVES Physicians are unable to reliably determine intravascular volume status through the clinical examination. Respiratory variation in the diameter of the inferior vena cava (IVC) has been investigated as a noninvasive marker of intravascular volume status; however, there has been a lack of standardization across investigations. The authors evaluated three locations along the IVC to determine if there is clinical equivalence of the respiratory percent collapse at these sites. The objective of this study was to determine the importance of location when measuring the IVC diameter during quiet respiration. METHODS Measurements of the IVC were obtained during quiet passive respiration in supine healthy volunteers. All images were recorded in B-mode, with cine-loop adjustments in real time, to ensure that maximum and minimum IVC dimensions were obtained. One-way repeated-measures analysis of variance (ANOVA) was used for comparison of IVC measurement sites. RESULTS The mean (+/-SD) percentage collapse was 20% (+/-16%) at the level of the diaphragm, 30% (+/-21%) at the level of the hepatic vein inlet, and 35% (+/-22%) at the level of the left renal vein. ANOVA revealed a significant overall effect for location of measurement, with F(2,35) = 6.00 and p = 0.006. Contrasts showed that the diaphragm percentage collapse was significantly smaller than the hepatic (F(1,36) = 5.14; p = 0.03) or renal caval index (F(1,36) = 11.85; p = 0.002). CONCLUSIONS Measurements of respiratory variation in IVC collapse in healthy volunteers are equivalent at the level of the left renal vein and at 2 cm caudal to the hepatic vein inlet. Measurements taken at the junction of the right atrium and IVC are not equivalent to the other sites; clinicians should avoid measuring percentage collapse of the IVC at this location.

Critical Care Bed Growth in the United States. A Comparison of Regional and National Trends

RATIONALE Although the number of intensive care unit (ICU) beds in the United States is increasing, it is unknown whether this trend is consistent across all regions. OBJECTIVES We sought to better characterize regional variation in ICU bed changes over time and identify regional characteristics associated with these changes. METHODS We used data from the Centers for Medicare and Medicaid Services and the U.S. Census to summarize the numbers of hospitals, hospital beds, ICU beds, and ICU occupancy at the level of Dartmouth Atlas hospital referral region from 2000 to 2009. We categorized regions into quartiles of bed change over the study interval and examined the relationship between change categories, regional characteristics, and population characteristics over time. MEASUREMENTS AND MAIN RESULTS From 2000 to 2009 the national number of ICU beds increased 15%, from 67,579 to 77,809, mirroring population. However, there was substantial regional variation in absolute changes (median, +16 ICU beds; interquartile range, -3 to +51) and population-adjusted changes (median, +0.9 ICU beds per 100,000; interquartile range, -3.8 to +5.9), with 25.0% of regions accounting for 74.8% of overall growth. At baseline, regions with increasing numbers of ICU beds had larger populations, lower ICU beds per 100,000 capita, higher average ICU occupancy, and greater market competition as measured by the Herfindahl-Hirschman Index (P < 0.001 for all comparisons). CONCLUSIONS National trends in ICU bed growth are not uniformly reflected at the regional level, with most growth occurring in a small number of highly populated regions.

Adoption of ICU telemedicine in the United States.

Objective:ICU telemedicine is a novel approach for providing critical care services from a distance. We sought to study the extent of use and patterns of adoption of this technology in U.S. ICUs. Design:Retrospective study combining a systematic listing of ICU telemedicine installations with hospital characteristic data from the Centers for Medicare and Medicaid Services. We examined adoption over time and compared hospital characteristics between facilities that have adopted ICU telemedicine and those that have not. Setting:U.S. ICUs. Setting:U.S. hospitals from 2002 to 2010. Interventions:None. Measurements and Main Results:The number of hospitals using ICU telemedicine increased from 16 (0.4% of total) to 213 (4.6% of total) between 2003 and 2010. The number of ICU beds covered by telemedicine increased from 598 (0.9% of total) to 5,799 (7.9% of total). The average annual rate of ICU bed coverage growth was 101% per year in the first four study years but slowed to 8.1% per year over the last four study years (p < 0.001 for difference in linear trend). Compared with non-adopting hospitals, hospitals adopting ICU telemedicine were more likely to be large (percentage with > 400 beds: 11.1% vs 3.7%, p < 0.001), teaching (percentage with resident coverage: 31.4% vs 21.9%, p = 0.003), and urban (percentage located in metropolitan statistical areas with more than 1 million residents: 45.3% vs 30.1%, p < 0.001). Conclusions:ICU telemedicine adoption was initially rapid but recently slowed. Efforts are needed to uncover the barriers to future growth, particularly regarding the optimal strategy for using this technology most effectively and efficiently.

The Volume-Outcome Relationship in Critical Care

OBJECTIVE The purpose of this study was to systematically review the research on volume and outcome relationships in critical care. METHODS From January 1, 2001, to April 30, 2014, MEDLINE and EMBASE were searched for studies assessing the relationship between admission volume and clinical outcomes in critical illness. Bibliographies were reviewed to identify other articles of interest, and experts were contacted about missing or unpublished studies. Of 127 studies reviewed, 46 met inclusion criteria, covering seven clinical conditions. Two investigators independently reviewed each article using a standardized form to abstract information on key study characteristics and results. RESULTS Overall, 29 of the studies (63%) reported a statistically significant association between higher admission volume and improved outcomes. The magnitude of the association (mortality OR between the lowest vs highest stratum of volume centers), as well as the thresholds used to characterize high volume, varied across clinical conditions. Critically ill patients with cardiovascular (n = 7, OR = 1.49 [1.11-2.00]), respiratory (n = 12, OR = 1.20 [1.04-1.38]), severe sepsis (n = 4, OR = 1.17 [1.03-1.33]), hepato-GI (n = 3, OR = 1.30 [1.08-1.78]), neurologic (n = 3, OR = 1.38 [1.22-1.57]), and postoperative admission diagnoses (n = 3, OR = 2.95 [1.05-8.30]) were more likely to benefit from admission to higher-volume centers compared with lower-volume centers. Studies that controlled for ICU or hospital organizational factors were less likely to find a significant volume-outcome relationship than studies that did not control for these factors. CONCLUSIONS Critically ill patients generally benefit from care in high-volume centers, with more substantial benefits in selected high-risk conditions. This relationship may in part be mediated by specific ICU and hospital organizational factors.

Nurse Practitioner/Physician Assistant Staffing and Critical Care Mortality

BACKGROUND ICUs are increasingly staffed with nurse practitioners/physician assistants (NPs/PAs), but it is unclear how NPs/PAs influence quality of care. We examined the association between NP/PA staffing and in-hospital mortality for patients in the ICU. METHODS We used retrospective cohort data from the 2009 to 2010 APACHE (Acute Physiology and Chronic Health Evaluation) clinical information system and an ICU-level survey. We included patients aged ≥ 17 years admitted to one of 29 adult medical and mixed medical/surgical ICUs in 22 US hospitals. Because this survey could not assign NPs/PAs to individual patients, the primary exposure was admission to an ICU where NPs/PAs participated in patient care. The primary outcome was patient-level in-hospital mortality. We used multivariable relative risk regression to examine the effect of NPs/PAs on in-hospital mortality, accounting for differences in case mix, ICU characteristics, and clustering of patients within ICUs. We also examined this relationship in the following subgroups: patients on mechanical ventilation, patients with the highest quartile of Acute Physiology Score (> 55), and ICUs with low-intensity physician staffing and with physician trainees. RESULTS Twenty-one ICUs (72.4%) reported NP/PA participation in direct patient care. Patients in ICUs with NPs/PAs had lower mean Acute Physiology Scores (42.4 vs 46.7, P < .001) and mechanical ventilation rates (38.8% vs 44.2%, P < .001) than ICUs without NPs/PAs. Unadjusted and risk-adjusted mortality was similar between groups (adjusted relative risk, 1.10; 95% CI, 0.92-1.31). This result was consistent in all examined subgroups. CONCLUSIONS NPs/PAs appear to be a safe adjunct to the ICU team. The findings support NP/PA management of critically ill patients.

Nighttime intensivist staffing and the timing of death among ICU decedents: a retrospective cohort study.

IntroductionIntensive care units (ICUs) are increasingly adopting 24-hour intensivist physician staffing. Although nighttime intensivist staffing does not consistently reduce mortality, it may affect other outcomes such as the quality of end-of-life care.MethodsWe conducted a retrospective cohort study of ICU decedents using the 2009–2010 Acute Physiology and Chronic Health Evaluation clinical information system linked to a survey of ICU staffing practices. We restricted the analysis to ICUs with high-intensity daytime staffing, in which the addition of nighttime staffing does not influence mortality. We used multivariable regression to assess the relationship between nighttime intensivist staffing and two separate outcomes potentially related to the quality of end-of-life care: time from ICU admission to death and death at night.ResultsOf 30,456 patients admitted to 27 high-intensity daytime staffed ICUs, 3,553 died in the hospital within 30 days. After adjustment for potential confounders, admission to an ICU with nighttime intensivist staffing was associated with a shorter duration between ICU admission and death (adjusted difference: –2.5 days, 95% CI -3.5 to -1.5, p-value < 0.001) and a decreased odds of nighttime death (adjusted odds ratio: 0.75, 95% CI 0.60 to 0.94, p-value 0.011) compared to admission to an ICU without nighttime intensivist staffing.ConclusionsAmong ICU decedents, nighttime intensivist staffing is associated with reduced time between ICU admission and death and reduced odds of nighttime death.

Geographic Access to High Capability Severe Acute Respiratory Failure Centers in the United States

Objective Optimal care of adults with severe acute respiratory failure requires specific resources and expertise. We sought to measure geographic access to these centers in the United States. Design Cross-sectional analysis of geographic access to high capability severe acute respiratory failure centers in the United States. We defined high capability centers using two criteria: (1) provision of adult extracorporeal membrane oxygenation (ECMO), based on either 2008–2013 Extracorporeal Life Support Organization reporting or provision of ECMO to 2010 Medicare beneficiaries; or (2) high annual hospital mechanical ventilation volume, based 2010 Medicare claims. Setting Nonfederal acute care hospitals in the United States. Measurements and Main Results We defined geographic access as the percentage of the state, region and national population with either direct or hospital-transferred access within one or two hours by air or ground transport. Of 4,822 acute care hospitals, 148 hospitals met our ECMO criteria and 447 hospitals met our mechanical ventilation criteria. Geographic access varied substantially across states and regions in the United States, depending on center criteria. Without interhospital transfer, an estimated 58.5% of the national adult population had geographic access to hospitals performing ECMO and 79.0% had geographic access to hospitals performing a high annual volume of mechanical ventilation. With interhospital transfer and under ideal circumstances, an estimated 96.4% of the national adult population had geographic access to hospitals performing ECMO and 98.6% had geographic access to hospitals performing a high annual volume of mechanical ventilation. However, this degree of geographic access required substantial interhospital transfer of patients, including up to two hours by air. Conclusions Geographic access to high capability severe acute respiratory failure centers varies widely across states and regions in the United States. Adequate referral center access in the case of disasters and pandemics will depend highly on local and regional care coordination across political boundaries.