A Pragmatic Pilot Trial Comparing Patient-Triggered Adaptive Pressure Control to Patient-Triggered Volume Control Ventilation in Critically Ill Adults

BACKGROUND

Patient-triggered adaptive pressure control (APC) continuous mandatory ventilation (CMV) (APC-CMV) has been widely adopted as an alternative ventilator mode to patient-triggered volume control (VC) CMV (VC-CMV). However, the comparative effectiveness of the 2 ventilator modes remains uncertain. We sought to explore clinical and implementation factors pertinent to a future definitive randomized controlled trial assessing APC-CMV versus VC-CMV as an initial ventilator mode strategy. The research objectives in our pilot trial tested clinician adherence and explored clinical outcomes.

METHODS

In a single-center pragmatic sequential cluster crossover pilot trial, we enrolled all eligible adults with acute respiratory failure requiring mechanical ventilation admitted during a 9-week period to the medical ICU. Two-week time epochs were assigned a priori in which subjects received either APC-CMV or VC-CMV The primary outcome of the trial was feasibility, defined as 80% of subjects receiving the assigned mode within 1 h of initiation of ICU ventilation. The secondary outcome was proportion of the first 24 h on the assigned mode. Finally, we surveyed clinician stakeholders to understand potential facilitators and barriers to conducting a definitive randomized trial.

RESULTS

We enrolled 137 subjects who received 152 discreet episodes of mechanical ventilation during time epochs assigned to APC-CMV (n = 61) and VC-CMV (n = 91). One hundred and thirty-one episodes were included in the prespecified primary outcome. One hundred and twenty-six (96%) received the assigned mode within the first hour of ICU admission (60 of 61 subjects assigned APC-CMV and 66 of 70 assigned VC-CMV). VC-CMV subjects spent a lower proportion of first 24 h (84% [95% CI 78-89]) on the assigned mode than APC-CMV recipients (95% [95% CI 91-100]). Mixed-methods analyses identified preconceived perceptions of subject comfort by clinicians and need for real-time education to address this concern.

CONCLUSIONS

In this pilot pragmatic, sequential crossover trial, unit-wide allocation to a ventilator mode was feasible and acceptable to clinicians.

A Survey to Assess Primary Care Physician Awareness of Complications Following Critical Illness

Background: Survivors of critical illness are at risk for post-intensive care syndrome (PICS, comprised of physical dysfunction, cognitive impairment, and neuropsychiatric disorders including anxiety, depression, and post-traumatic stress). Their family members and caregivers are at risk for PICS-F (PICS-family, comprised of anxiety, depression, post-traumatic stress). PICS and PICS-F are increasingly recognized in critical care; however, the awareness among primary providers of the domains and the terms of PICS/PICS-F is unknown. Objectives: To determine current practice patterns and knowledge among primary care physicians in regards to patients recovering from critical illness; to determine barriers to care of post-critically ill patients. Methods: A paper and electronic survey were developed and randomly distributed to a subset of North Carolina primary care physicians. Survey questions consisted of the following domains: demographics, current practice, barriers to providing care, knowledge of common issues/complications following critical illness, and interest in changing care for survivors of critical illness. Results: One hundred and ninety-six surveys were delivered and 77 completed surveys (39% response rate) were analyzed. Respondents confirmed significant barriers to care of post-critically ill patients including lack of awareness of PICS/PICS-F terminology, insufficient time to spend with patients, and inadequate education of patients/families about recovery after critical illness. Fifty-seven percent of respondents thought a specialized transitional post-ICU clinic would be helpful. Sixty-two percent reported feeling comfortable caring for patients after a critical illness and 75% felt they were aware of common problems encountered after critical illness. However, 84% also thought more education about PICS/PICS-F would be helpful as would a list of common problems seen after critical illness (91%). Conclusions: Significant gaps and barriers to providing optimal post-ICU care by PCPs exist. Providers identified time constraints and educational gaps as domains needing attention. Dedicated post-ICU clinics might provide a bridge to transition care post-critical illness back to primary care providers.

A Survey of Implementation of ABCDE Protocols

BACKGROUND

Spontaneous awakening trials (SATs), spontaneous breathing trials (SBTs), delirium assessment/management, early mobility have been termed the ABCDE bundle. The ABCDE bundle has been proven to improve patient outcomes. However, there is often a long gap in dissemination and implementation of evidence-based medicine.

OBJECTIVES

To determine the prevalent implementation of and determinants for ABCDE protocol adoption in Pennsylvania.

METHODS

We developed a survey of ABCDE bundle protocols. We surveyed factors around implementation including written protocol presence, standardized assessments to guide protocols, timing of creation of protocols, and estimated adherence to protocols. We also collected data on factors that might be determinants for protocol adoption including ICU staffing models, hospital and ICU level factors. We validated the survey tool using the Michigan Health and Hospital Association Keystone ICU collaborative. We then administered the validated survey to a leader of the medical ICU or mixed medical-surgical ICU of all Pennsylvania Hospitals. Multivariable logistic and ordinal regression were used to determine associations between ICU staffing models and hospital and ICU level factors with the presence of ABCDE bundle protocols.

RESULTS

In the study cohort of Pennsylvania ICUs (n = 144), we had 100 respondents (69% response). The median number of hospital beds among the respondents was 185 (IQR 111-355) with a median of 14 ICU beds (IQR 10-20). 86% reported spontaneous awakening trial protocols, 60% reported spontaneous breathing trial protocols, 43% reported delirium assessment/management protocols, and 27% reported early mobility protocols. Being a medical ICU compared to a mixed medical-surgical ICU (OR 3.48, 95% CI 1.19-10.21, P = .02) and presence of multidisciplinary rounds (OR 4.97, 95% CI 2.07-11.94, P < .001) were associated with increasing number of ABCDE bundle protocol components.

CONCLUSIONS

Variable implementation of ABCDE bundle protocols was present across Pennsylvania. Team communication is important to implementation of these protocols.

Activity Levels in Survivors of the Intensive Care Unit

OBJECTIVE

Limited data exist on the quantification of activity levels and functional status in critically ill patients as they transition from the intensive care unit (ICU) to the wards and, subsequently, back into the community. The physical activity of critically ill patients from their ICU stay until 7 days after hospital discharge was characterized, as well as correlate physical activity levels with an objective measure of physical function.

METHODS

This prospective observational study of previously independent adults aged 55 or older, undergoing mechanical ventilation for up to 7 days, recruited participants at the time of spontaneous breathing trials or less than 24 hours after extubation. Participants received an accelerometer at enrollment to wear until 1 week after discharge.

RESULTS

Twenty-two participants received accelerometers; 15 were suitable for analysis. Participants had a mean (SD) age of 68 (9.6) years; 47% were female. Mean step counts were 95 (95% CI = 15-173) in the 3 days before ICU discharge, 257 (95% CI = 114-400) before hospital discharge, 1223 (95% CI = 376-2070) in the first 3 days at home, and 1278 (95% CI = 349-2207) between day 4 and 6 post-hospital discharge. Physical activity was significantly higher post- compared with pre-hospital discharge. Short Physical Performance Battery scores were poor at ICU and hospital discharge; however, they correlated moderately with physical activity levels immediately upon return home.

CONCLUSIONS

Physical activity remained low as survivors of critical illness transitioned from ICU to hospital wards, but significantly increased upon return to the community. Despite poor Short Physical Performance Battery scores at both ICU and hospital discharge, participants were significantly more active immediately after discharge than in their last 3 days of hospitalization. This may represent rapid functional improvement or, conversely, constrained physical activity in hospital.

IMPACT

This study highlights the need for further evaluation of physical activity constraints in hospital and ways to augment physical activity and function upon discharge.

LAY SUMMARY

Physical activity (step counts) increased modestly as survivors of critical illness transitioned from ICU to hospital wards, but significantly increased upon return to the community. This study highlights the need for further evaluation of physical activity constraints in the hospital setting and ways to augment physical activity and function postdischarge.

Benefits of Peer Support for Intensive Care Unit Survivors: Sharing Experiences, Care Debriefing, and Altruism

BACKGROUND

After critical illness, patients are often left with impairments in physical, social, emotional, and cognitive functioning. Peer support interventions have been implemented internationally to ameliorate these issues.

OBJECTIVE

To explore what patients believed to be the key mechanisms of effectiveness of peer support programs implemented during critical care recovery.

METHODS

In a secondary analysis of an international qualitative data set, 66 telephone interviews with patients were undertaken across 14 sites in Australia, the United Kingdom, and the United States to understand the effect of peer support during recovery from critical illness. Prevalent themes were documented with framework analysis.

RESULTS

Most patients who had been involved in peer support programs reported benefit. Patients described 3 primary mechanisms: (1) sharing experiences, (2) care debriefing, and (3) altruism.

CONCLUSION

Peer support is a relatively simple intervention that could be implemented to support patients during recovery from critical illness. However, more research is required into how these programs can be implemented in a safe and sustainable way in clinical practice.

Echogenicity Is Related to Skeletal Muscle Strength in Patients With Acute Respiratory Failure

PURPOSE

Patients with acute respiratory failure (ARF) show changes in skeletal muscle structure and strength. The purpose of this study was to examine the relationship between muscle thickness, echogenicity, and strength in patients with ARF.

METHODS

Thirteen (6 females, 7 males) patients with ARF participated in the study. Knee extensor strength was measured via a handheld dynamometer and quadriceps images were obtained via ultrasonography at hospital discharge. The ultrasonograms were used to obtain muscle thickness and both mean ± SD echogenicity of the rectus femoris, vastus lateralis, and vastus medialis. Partial correlations, controlling for age, body mass index, and fluid intake were used to describe the relationships among knee extensor strength and echogenicity and muscle thickness.

RESULTS

Knee extensor strength and vastus lateralis SD echogenicity were significantly correlated when controlling for age, body mass index, and fluid intake (r = 0.69, P = .029). Knee extensor strength and vastus lateralis echogenicity were 19.1 ± 8.0 kg and 19.8 ± 5.4 units, respectively. No other correlations between strength and ultrasound measures were found to be significant.

CONCLUSION

These results show skeletal muscle echogenicity to be significantly correlated with skeletal muscle strength in patients with ARF. As such, it may be useful in identifying muscle weakness in these patients when they are unable or unwilling to perform voluntary strength testing.

Enablers and Barriers to Implementing ICU Follow-Up Clinics and Peer Support Groups Following Critical Illness: The Thrive Collaboratives

OBJECTIVES

Data are lacking regarding implementation of novel strategies such as follow-up clinics and peer support groups, to reduce the burden of postintensive care syndrome. We sought to discover enablers that helped hospital-based clinicians establish post-ICU clinics and peer support programs, and identify barriers that challenged them.

DESIGN

Qualitative inquiry. The Consolidated Framework for Implementation Research was used to organize and analyze data.

SETTING

Two learning collaboratives (ICU follow-up clinics and peer support groups), representing 21 sites, across three continents.

SUBJECTS

Clinicians from 21 sites.

MEASUREMENT AND MAIN RESULTS

Ten enablers and nine barriers to implementation of "ICU follow-up clinics" were described. A key enabler to generate support for clinics was providing insight into the human experience of survivorship, to obtain interest from hospital administrators. Significant barriers included patient and family lack of access to clinics and clinic funding. Nine enablers and five barriers to the implementation of "peer support groups" were identified. Key enablers included developing infrastructure to support successful operationalization of this complex intervention, flexibility about when peer support should be offered, belonging to the international learning collaborative. Significant barriers related to limited attendance by patients and families due to challenges in creating awareness, and uncertainty about who might be appropriate to attend and target in advertising.

CONCLUSIONS

Several enablers and barriers to implementing ICU follow-up clinics and peer support groups should be taken into account and leveraged to improve ICU recovery. Among the most important enablers are motivated clinician leaders who persist to find a path forward despite obstacles.

A randomized pilot study of nitrate supplementation with beetroot juice in acute respiratory failure

Nitrate rich beetroot juice (BRJ) can enhance nitric oxide signaling, leading to improved physical function in healthy and diseased populations, but its safety and biologic efficacy have not been evaluated in a critically ill population. We randomized 22 previously functional acute respiratory failure patients to either BRJ or placebo daily until day 14 or discharge. We measured blood nitrate and nitrite levels and quantified strength and physical function at intensive care unit (ICU) and hospital discharge. Participants were predominantly male (54%), aged 68.5 years with an APACHE III score of 62. BRJ increased plasma nitrate (mean 219.2 μM increase, p = 0.002) and nitrite levels (mean 0.144 μM increase, p = 0.02). We identified no adverse events. The unadjusted and adjusted effect sizes of the intervention on the short physical performance battery were small (d = 0.12 and d = 0.17, respectively). In this pilot trial, administration of BRJ was feasible and safe, increased blood nitrate and nitrate levels, but had a small effect on physical function. Future studies could evaluate the clinical efficacy of BRJ as a therapy to improve physical function in survivors of critical illness.

Implementation of an ICU Recovery Clinic at a Tertiary Care Academic Center

Post-ICU clinics may facilitate the care of survivors of critical illness, but there is a paucity of data describing post-ICU clinic implementation. We sought to describe implementation of our ICU recovery clinic, including an assessment of barriers and facilitators to clinic attendance.

DESIGN

Adults admitted to the medical ICU of a large tertiary care academic hospital with shock and/or respiratory failure requiring mechanical ventilation were screened for participation in a newly formed ICU recovery clinic. Participant selection and attendance rates were tracked. Reasons for nonattendance were assessed by phone call in a subset of patients.

SETTING

A newly formed ICU recovery clinic of a large tertiary care academic hospital.

PATIENTS

All patients admitted to the medical ICU were screened.

INTERVENTIONS

ICU recovery clinic appointments were scheduled for all eligible patients. A subset of nonattenders were called to assess reasons for nonattendance.

MEASUREMENTS AND MAIN RESULTS

Over 2 years, we admitted 5,510 patients to our medical ICU. Three hundred sixty-two were screened into the recovery clinic. One-hundred sixty-six were not scheduled for clinic; major reasons included discharge to hospice/death in the hospital (n = 55) and discharge to a facility (n = 50). One-hundred ninety-six patients were scheduled for a visit and of those, 101 (52%) arrived to clinic. Reasons for nonattendance in a surveyed subset of nonattenders included patient's lack of awareness of the appointment (50%, n = 9/18), financial concerns (17%, n = 3/18), and transportation difficulty (17%, n = 3/18).

CONCLUSIONS

ICU recovery clinics may address the needs of survivors of critical illness. Barriers to clinic attendance include high mortality rates, high rates of clinic appointment cancelations and nonattendance, and discharge to locations such as skilled nursing facilities or long-term acute care hospitals. Improved communication to patients about the role of the clinic may facilitate attendance and minimize canceled appointments.

Association of Hyperchloremia With Unfavorable Clinical Outcomes in Adults With Diabetic Ketoacidosis

OBJECTIVE

Hyperchloremia is associated with worsened outcomes in various clinical situations; however, data are limited in patients with diabetic ketoacidosis (DKA). The purpose of this study was to determine the effect of hyperchloremia on time to DKA resolution.

METHODS

We conducted a retrospective cohort study of adult patients admitted with incident DKA from January 2013 through October 2017 and stratified by the development of hyperchloremia versus maintaining normochloremia. The primary outcome was time to final DKA resolution. Secondary outcomes included time to initial DKA resolution, incidence of acute kidney injury (AKI) on admission, in-hospital development of AKI, and hospital length of stay (LOS).

RESULTS

Of the 102 patients included, 52 developed hyperchloremia. Patients with hyperchloremia had longer times to final DKA resolution compared to those with normochloremia (median 22.3 [interquartile range, IQR, 15.2-36.9] vs 14.2 [IQR 8.8-21.1] hours; P = .001). Time to initial DKA resolution was also longer in patients who developed hyperchloremia compared to those who did not (median 16.3 vs 10.9 hours; P = .024). More patients with hyperchloremia developed in-hospital AKI (26.9% vs 8.0%; P = .01). Median hospital LOS was significantly longer in the hyperchloremia cohort (P < .001). On Cox regression analysis, time to DKA resolution was significantly longer with each 1 mmol/L increase in serum chloride (HR 0.951; P < .001).

CONCLUSION

The presence of hyperchloremia in patients with DKA was associated with increased time to DKA resolution, risk of in-hospital AKI, and hospital LOS. Further evaluation of the avoidance or treatment of hyperchloremia in DKA is needed.

Key mechanisms by which post-ICU activities can improve in-ICU care: results of the international THRIVE collaboratives

Objective

To identify the key mechanisms that clinicians perceive improve care in the intensive care unit (ICU), as a result of their involvement in post-ICU programs.

Methods

Qualitative inquiry via focus groups and interviews with members of the Society of Critical Care Medicine’s THRIVE collaborative sites (follow-up clinics and peer support). Framework analysis was used to synthesize and interpret the data.

Results

Five key mechanisms were identified as drivers of improvement back into the ICU: (1) identifying otherwise unseen targets for ICU quality improvement or education programs—new ideas for quality improvement were generated and greater attention paid to detail in clinical care. (2) Creating a new role for survivors in the ICU—former patients and family members adopted an advocacy or peer volunteer role. (3) Inviting critical care providers to the post-ICU program to educate, sensitize, and motivate them—clinician peers and trainees were invited to attend as a helpful learning strategy to gain insights into post-ICU care requirements. (4) Changing clinician’s own understanding of patient experience—there appeared to be a direct individual benefit from working in post-ICU programs. (5) Improving morale and meaningfulness of ICU work—this was achieved by closing the feedback loop to ICU clinicians regarding patient and family outcomes.

Conclusions

The follow-up of patients and families in post-ICU care settings is perceived to improve care within the ICU via five key mechanisms. Further research is required in this novel area.

Electronic supplementary material

The online version of this article (10.1007/s00134-019-05647-5) contains supplementary material, which is available to authorized users.

The relationship between self-report and performance-based measures of physical function following an ICU stay

PURPOSE

To examine relationships between self-report and performance-based measures of physical function in ICU patients randomized to standardized rehabilitation therapy (SRT) or usual care (UC).

METHODS

Physical function was assessed in 257 ICU patients using self-report (physical functioning scale of the SF-36 (SF-36 PFS)) and the functional performance inventory-short form (FPI-SF) as well as performance-based measures (Short Physical Performance Battery (SPPB)) and muscular strength (MS). Assessments were at hospital discharge, 2, 4, and 6 months.

RESULTS

Correlations between self-report and performance-based measures were not significantly different between the two groups. When examining the entire cohort, a significant, but weak, correlation (r = 0.286) was found between the SF-36 PFS and the SPPB. At 2 months, moderate correlations were found between self-report and performance-based measures. The SF-36 PFS and FPI were significantly correlated with the SPPB (r = 0.536 and 0.553, respectively) and muscular strength (r = 0.413 and 0.431, respectively). Similar associations were seen at 4 and 6 months in both groups.

CONCLUSION

Self-report and performance-based measures of physical function appear to assess different constructs at hospital discharge. Following recovery, these measures converge, but indicate different constructs are being assessed. As such, both self-report and performance-based measures of physical function should be used with ICU patients.

Physical function impairment in survivors of critical illness in an ICU Recovery Clinic

PURPOSE

The aims were to 1) determine feasibility of measuring physical function in our ICU Recovery Clinic (RC), 2) determine if physical function was associated with 6-month re-hospitalization and 1-year mortality and 3) compare ICU survivors' physical function to other comorbid populations.

MATERIALS AND METHODS

We established the Wake Forest ICU RC. Patients were seen in clinic 1month following hospital discharge. Testing included the Short Form-36 questionnaire and Short Physical Performance Battery (SPPB). We related these measures to 6month re-hospitalizations and 1year mortality, and compared patients' functional performance with other comorbid populations.

RESULTS

Thirty-six patients were seen in clinic from July 2014 to June 2015; the median SPPB score was 5 (IQR 5). The median SF-36 physical component summary score was 21.8 (IQR 28.8). Mortality was 14% at 1year. Of those who did not die by 1year, 35% were readmitted to our hospital within 6months of hospital discharge. SPPB scores demonstrated a non-significant trend with both mortality (p=0.06) and readmissions (p=0.09). ICU survivors' SPPB scores were significantly lower than those of other chronically ill populations (p<0.001).

CONCLUSIONS

Physical function measurement in a recovery clinic is feasible and may inform subsequent morbidity and mortality.

Standardized Rehabilitation and Hospital Length of Stay Among Patients With Acute Respiratory Failure: A Randomized Clinical Trial

IMPORTANCE

Physical rehabilitation in the intensive care unit (ICU) may improve the outcomes of patients with acute respiratory failure.

OBJECTIVE

To compare standardized rehabilitation therapy (SRT) to usual ICU care in acute respiratory failure.

DESIGN, SETTING, AND PARTICIPANTS

Single-center, randomized clinical trial at Wake Forest Baptist Medical Center, North Carolina. Adult patients (mean age, 58 years; women, 55%) admitted to the ICU with acute respiratory failure requiring mechanical ventilation were randomized to SRT (n=150) or usual care (n=150) from October 2009 through May 2014 with 6-month follow-up.

INTERVENTIONS

Patients in the SRT group received daily therapy until hospital discharge, consisting of passive range of motion, physical therapy, and progressive resistance exercise. The usual care group received weekday physical therapy when ordered by the clinical team. For the SRT group, the median (interquartile range [IQR]) days of delivery of therapy were 8.0 (5.0-14.0) for passive range of motion, 5.0 (3.0-8.0) for physical therapy, and 3.0 (1.0-5.0) for progressive resistance exercise. The median days of delivery of physical therapy for the usual care group was 1.0 (IQR, 0.0-8.0).

MAIN OUTCOMES AND MEASURES

Both groups underwent assessor-blinded testing at ICU and hospital discharge and at 2, 4, and 6 months. The primary outcome was hospital length of stay (LOS). Secondary outcomes were ventilator days, ICU days, Short Physical Performance Battery (SPPB) score, 36-item Short-Form Health Surveys (SF-36) for physical and mental health and physical function scale score, Functional Performance Inventory (FPI) score, Mini-Mental State Examination (MMSE) score, and handgrip and handheld dynamometer strength.

RESULTS

Among 300 randomized patients, the median hospital LOS was 10 days (IQR, 6 to 17) for the SRT group and 10 days (IQR, 7 to 16) for the usual care group (median difference, 0 [95% CI, -1.5 to 3], P = .41). There was no difference in duration of ventilation or ICU care. There was no effect at 6 months for handgrip (difference, 2.0 kg [95% CI, -1.3 to 5.4], P = .23) and handheld dynamometer strength (difference, 0.4 lb [95% CI, -2.9 to 3.7], P = .82), SF-36 physical health score (difference, 3.4 [95% CI, -0.02 to 7.0], P = .05), SF-36 mental health score (difference, 2.4 [95% CI, -1.2 to 6.0], P = .19), or MMSE score (difference, 0.6 [95% CI, -0.2 to 1.4], P = .17). There were higher scores at 6 months in the SRT group for the SPPB score (difference, 1.1 [95% CI, 0.04 to 2.1, P = .04), SF-36 physical function scale score (difference, 12.2 [95% CI, 3.8 to 20.7], P = .001), and the FPI score (difference, 0.2 [95% CI, 0.04 to 0.4], P = .02).

CONCLUSIONS AND RELEVANCE

Among patients hospitalized with acute respiratory failure, SRT compared with usual care did not decrease hospital LOS.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00976833.

A randomized trial of nighttime physician staffing in an intensive care unit

BACKGROUND

Increasing numbers of intensive care units (ICUs) are adopting the practice of nighttime intensivist staffing despite the lack of experimental evidence of its effectiveness.

METHODS

We conducted a 1-year randomized trial in an academic medical ICU of the effects of nighttime staffing with in-hospital intensivists (intervention) as compared with nighttime coverage by daytime intensivists who were available for consultation by telephone (control). We randomly assigned blocks of 7 consecutive nights to the intervention or the control strategy. The primary outcome was patients' length of stay in the ICU. Secondary outcomes were patients' length of stay in the hospital, ICU and in-hospital mortality, discharge disposition, and rates of readmission to the ICU. For length-of-stay outcomes, we performed time-to-event analyses, with data censored at the time of a patient's death or transfer to another ICU.

RESULTS

A total of 1598 patients were included in the analyses. The median Acute Physiology and Chronic Health Evaluation (APACHE) III score (in which scores range from 0 to 299, with higher scores indicating more severe illness) was 67 (interquartile range, 47 to 91), the median length of stay in the ICU was 52.7 hours (interquartile range, 29.0 to 113.4), and mortality in the ICU was 18%. Patients who were admitted on intervention days were exposed to nighttime intensivists on more nights than were patients admitted on control days (median, 100% of nights [interquartile range, 67 to 100] vs. median, 0% [interquartile range, 0 to 33]; P<0.001). Nonetheless, intensivist staffing on the night of admission did not have a significant effect on the length of stay in the ICU (rate ratio for the time to ICU discharge, 0.98; 95% confidence interval [CI], 0.88 to 1.09; P=0.72), ICU mortality (relative risk, 1.07; 95% CI, 0.90 to 1.28), or any other end point. Analyses restricted to patients who were admitted at night showed similar results, as did sensitivity analyses that used different definitions of exposure and outcome.

CONCLUSIONS

In an academic medical ICU in the United States, nighttime in-hospital intensivist staffing did not improve patient outcomes. (Funded by University of Pennsylvania Health System and others; ClinicalTrials.gov number, NCT01434823.).

Gene discovery in the embryonic chick retina

PURPOSE

The chick embryo is a powerful model system for the study of retinal development. However, analysis of gene expression in the chick retina has lagged behind biological studies. The purpose of this study was to identity and characterize genes expressed in the chick embryo retina as candidate molecules involved in the development and function of photoreceptors and other retinal cell types.

METHODS

RNA from embryonic day (ED) 18 White Leghorn chick embryo retinae was used to generate an oligo dT-primed cDNA library. Bacterial colonies representing five thousand individual clones were arrayed onto nylon membranes using a microarray robot. Replicate membranes were hybridized with cDNA probes synthesized from ED 18 retina, brain and liver. Clones that appeared preferentially expressed in retina were identified by homology searches, and their spatial and temporal expression patterns were analyzed by in situ hybridization.

RESULTS

Two hundred and seventy-two clones were identified. Approximately forty percent of the clones represented potential novel genes, including ESTs, hypothetical proteins and clones with no assigned identities. Furthermore, many genes were identified that are the putative chick orthologues of genes cloned from other species. We determined the expression pattern of several clones for which sequence homologies suggested possible roles in transcriptional regulation, apoptosis or intercellular signaling. Their corresponding mRNAs were expressed in the embryonic retina in topographically specific, developmentally regulated patterns.

CONCLUSIONS

We identified and characterized genes in the chick embryo retina using a combination of microarray analysis and in situ hybridization. Analysis of the expression patterns suggests involvement of several of these genes in key events during embryogenesis.