Biochemical response to treatment of bone hyperresorption in chronically critically ill patients

Pathophysiology and Therapeutic Management of Bone Loss in Patients with Critical Illness

Patients with critical illnesses are at higher risk of comorbidities, which can include bone mineral density loss, bone turnover marker increase, and fragility fractures. Patients admitted to intensive care units (ICUs) have a higher risk of bone fractures. Since hypermetabolism is a characteristic of ICU patients, such patients are often rapidly affected by systemic deterioration, which often results in systemic wasting disease. Major risk factors for ICU-related bone loss include physical restraint, inflammation, neuroendocrine stress, malnutrition, and medications. A medical history of critical illness should be acknowledged as a risk factor for impaired bone metabolism. Bone loss associated with ICU admission should be recognized as a key component of post-intensive care syndrome, and further research that focuses on treatment protocols and prevention strategies is required. Studies aimed at maintaining gut integrity have emphasized protein administration and nutrition, while research is ongoing to evaluate the therapeutic benefits of anti-resorptive agents and physical therapy. This review examines both current and innovative clinical strategies that are used for identifying risk factors of bone loss. It provides an overview of perioperative outcomes and discusses the emerging novel treatment modalities. Furthermore, the review presents future directions in the treatment of ICU-related bone loss.

Reduction in Hypercalcemia Following Readjustment of Target Serum 25-Hydroxy Vitamin D Concentration during Cholecalciferol Therapy in Vitamin D-Deficient Critically Ill Patients

The intent of this study was an evaluation of our effort to reduce the incidence of hypercalcemia in critically ill vitamin D-deficient patients with multiple traumatic injuries given cholecalciferol. Vitamin D deficiency was defined as a serum 25-hydroxy vitamin D concentration (25-OH vit D) of <20 ng/mL. Adult patients (>17 years of age) were given 10,000 IU of cholecalciferol daily with an intended target 25-OH vit D of >19.9 ng/mL. These patients were compared to a historical control group that underwent therapy with a higher target of >29.9 ng/mL. Patients received cholecalciferol via the feeding tube along with enteral nutrition (EN) until the target 25-OH vit D was achieved, EN discontinued, the nutrition support service signed off the patient, or the patient was discharged from the TICU. Patients were included if two consecutive weekly 25-OH vit D were measured. One hundred and three critically ill trauma patients were retrospectively studied. Fifty were given cholecalciferol therapy with the new lower target 25-OH vit D, and 53 were from a historical cohort aiming for the higher target. Hypercalcemia (serum ionized calcium concentration > 1.32 mmol/L) was reduced from 40% (21 out of 53 patients) to 4% (2 out of 50 patients; p < 0.001). None of the hypercalcemic patients were symptomatic. Readjustment of target 25-OH vit D concentration resulted in a ten-fold decrease in the rate of hypercalcemia and improved the safety of cholecalciferol therapy for critically ill patients with traumatic injuries.

Bone function, dysfunction and its role in diseases including critical illness

The skeleton is one of the largest organs in the human body. In addition to its conventional functions such as support, movement and protection, the skeleton also contributes to whole body homeostasis and maintenance of multiple important non-bone organs/systems (extraskeletal functions). Both conventional and extraskeletal functions of the skeleton are defined as bone function. Bone-derived factors (BDFs) are key players regulating bone function. In some pathophysiological situations, including diseases affecting bone and/or other organs/systems, the disorders of bone itself and the subsequently impaired functions of extraskeletal organs/systems caused by abnormal bone (impaired extraskeletal functions of bone) are defined as bone dysfunction. In critical illness, which is a health status characterized by the dysfunction or severe damage of one or multiple important organs or systems, the skeleton shows rapid bone loss resulting from bone hyper-resorption and impaired osteoblast function. In addition, the dysfunctions of the skeleton itself are also closely related to the severity and prognosis of critical illness. Therefore, we propose that there is bone dysfunction in critical illness. Some methods to inhibit osteoclast activity or promote osteoblast function by the treatment of bisphosphonates or PTH1-34 benefit the outcome of critical illness, which indicates that enhancing bone function may be a potential novel strategy to improve prognosis of diseases including critical illness.

Osteoporosis and the Critically Ill Patient

Improved survival after critical illness has led to recognition of impaired recovery following critical illness as a major public health problem. A consistent association between critical illness and accelerated bone loss has been described, including changes in bone turnover markers, bone mineral density, and fragility fracture rate. An association between accelerated bone turnover and increased mortality after critical illness is probable. Assessment of the effect of antifracture agents on fracture rate and mortality in the high-risk population of postmenopausal women with prolonged ventilation is warranted.

Changes in bone mineral density in women before critical illness: a matched control nested cohort study

The contribution of premorbid bone health to accelerated bone loss following critical illness is unknown. This study compared bone density in women before critical illness to women who did not become critically ill. Overall bone density was similar, although femoral neck bone mass increased immediately prior to critical illness.

PURPOSE

The relative contribution of acute and chronic factors to accelerated loss of bone mineral density (BMD) following critical illness is unknown. This study compared the BMD trajectory of women before critical illness to the BMD trajectory of women who did not become critically ill.

METHODS

This prospective, nested, age- and medication-matched, case-control study compared trajectory of BMD in women in the Geelong Osteoporosis study (GOS) requiring admission to an Australian Intensive Care Unit (ICU) between June 1998 and March 2016, to women not admitted to ICU. The main outcome was age and medication use adjusted change in BMD.

RESULTS

A total of 52 women, with a mean age of 77 ± 9 years were admitted to ICU, predominantly post-surgery (75%), during the study period. A greater age-adjusted annual rate of decline was observed for pre-ICU women compared to no-ICU women for AP spine BMD (-0.010 ± 0.002 g/cm² vs -0.005 ± 0.002 g/cm², p = 0.01) over the 15-year study period. In participants with multiple BMDs 2 years before critical illness, a significantly greater increase in femoral neck BMD compared to age- and medication-matched controls was observed (difference in BMD, ICU vs no-ICU = 0.037 ± 0.013 g/cm², p = 0.006).

CONCLUSION

In a cohort of women with predominantly surgical ICU admission, bone health prior to critical illness was comparable to age- and medication-matched controls, with a relative increase in femoral neck bone mass immediately prior to critical illness. These findings suggest critical illness-related bone loss cannot be entirely explained as a continuation of pre-morbid bone trajectory.

Chronic critical illness: are we saving patients or creating victims?

The technological advancements that allow support for organ dysfunction have led to an increase in survival rates for the most critically ill patients. Some of these patients survive the initial acute critical condition but continue to suffer from organ dysfunction and remain in an inflammatory state for long periods of time. This group of critically ill patients has been described since the 1980s and has had different diagnostic criteria over the years. These patients are known to have lengthy hospital stays, undergo significant alterations in muscle and bone metabolism, show immunodeficiency, consume substantial health resources, have reduced functional and cognitive capacity after discharge, create a sizable workload for caregivers, and present high long-term mortality rates. The aim of this review is to report on the most current evidence in terms of the definition, pathophysiology, clinical manifestations, treatment, and prognosis of persistent critical illness.

Sepsis Reduces Bone Strength Before Morphologic Changes Are Identifiable

OBJECTIVES

Survivors of critical illness have an increased prevalence of bone fractures. However, early changes in bone strength, and their relationship to structural changes, have not been described. We aimed to characterize early changes in bone functional properties in critical illness and their relationship to changes in bone structure, using a sepsis rodent model.

DESIGN

Experimental study.

SETTING

Animal research laboratory.

SUBJECTS

Adult Sprague-Dawley rats.

INTERVENTIONS

Forty Sprague-Dawley rats were randomized to cecal ligation and puncture or sham surgery. Twenty rodents (10 cecal ligation and puncture, 10 sham) were killed at 24 hours, and 20 more at 96 hours.

MEASUREMENTS AND MAIN RESULTS

Femoral bones were harvested for strength testing, microCT imaging, histologic analysis, and multifrequency scanning probe microscopy. Fracture loads at the femoral neck were significantly reduced for cecal ligation and puncture-exposed rodents at 24 hours (83.39 ± 10.1 vs 103.1 ± 17.6 N; p = 0.014) and 96 hours (81.60 ± 14.2 vs 95.66 ± 14.3 N; p = 0.047). Using multifrequency scanning probe microscopy, collagen elastic modulus was lower in cecal ligation and puncture-exposed rats at 24 hours (1.37 ± 0.2 vs 6.13 ± 0.3 GPa; p = 0.001) and 96 hours (5.57 ± 0.5 vs 6.13 ± 0.3 GPa; p = 0.006). Bone mineral elastic modulus was similar at 24 hours but reduced in cecal ligation and puncture-exposed rodents at 96 hours (75.34 ± 13.2 vs 134.4 ± 8.2 GPa; p < 0.001). There were no bone architectural or bone mineral density differences by microCT. Similarly, histologic analysis demonstrated no difference in collagen and elastin staining, and C-X-C chemokine receptor type 4, nuclear factor kappa beta, and tartrate-resistant acid phosphatase immunostaining.

CONCLUSIONS

In a rodent sepsis model, trabecular bone strength is functionally reduced within 24 hours and is associated with a reduction in collagen and mineral elastic modulus. This is likely to be the result of altered biomechanical properties, rather than increased bone mineral turnover. These data offer both mechanistic insights and may potentially guide development of therapeutic interventions.

Effect of vitamin D3 on bone turnover markers in critical illness: post hoc analysis from the VITdAL-ICU study

In this post hoc analysis of the VITdAL-ICU study, an RCT in critically ill adults with 25-hydroxyvitamin D levels ≤20 ng/ml, vitamin D3 did not have a significant effect on β-Crosslaps and osteocalcin.

INTRODUCTION

Observational studies have shown accelerated bone loss in ICU survivors. A reversible contributor is vitamin D deficiency. In a post hoc analysis of the VITdAL-ICU study, we evaluated the effect of high-dose vitamin D3 on the bone turnover markers (BTM) β-Crosslaps (CTX) and osteocalcin (OC).

METHODS

The VITdAL-ICU study was a randomized, double-blind, placebo-controlled trial in critically ill adults with 25-hydroxyvitamin D levels ≤20 ng/ml who received placebo or high-dose vitamin D3 (a loading dose of 540,000 IU and starting 1 month after the loading dose five monthly maintenance doses of 90,000 IU). In this analysis on 289 survivors (209 telephone, 80 personal follow-up visits), BTM were analyzed on days 0, 3, 7, 28, and 180; self-reported falls and fractures were assessed. Bone mineral density (BMD) was measured after 6 months.

RESULTS

At baseline, CTX was elevated; OC was low in both groups-after 6 months, both had returned to normal. There were no differences between groups concerning BTM, BMD, falls, or fractures. In linear mixed effects models, CTX and OC showed a significant change over time (p < 0.001, respectively), but there was no difference between the vitamin D and placebo group (p = 0.688 and p = 0.972, respectively).

CONCLUSIONS

Vitamin D supplementation did not have a significant effect on BTM. Further studies should assess the effectiveness of vitamin D on musculoskeletal outcomes in ICU survivors.

Bone Failure in Critical Illness

OBJECTIVES

The origin of systemic inflammatory response syndrome and multiple organ dysfunction syndrome is poorly understood but remains a fundamental concern in the ICU. This paper provides a critical appraisal on whether bone failure may represent an unrecognized component of systemic inflammatory response syndrome/multiple organ dysfunction syndrome.

DATA SOURCES, DATA SELECTION, AND DATA EXTRACTION

Search of the PubMed database and manual review of selected articles investigating bone pathophysiology in critical illness.

DATA SYNTHESIS

Bone hyperresorption is highly prevalent among critically ill patients. Bone breakdown releases numerous systemically active cytokines and bone-sequestered toxins, with the capacity to fuel inflammatory hypercytokinaemia and metabolic toxaemia. Anti-resorptive medication inhibits bone break down and preadmission anti-resorptive use is associated with superior survival among critically ill patients.

CONCLUSIONS

We propose that hyperresorptive bone failure is an unrecognised component of systemic inflammatory response syndrome/multiple organ dysfunction syndrome that is causal to critical illness progression. If this hypothesis is valid, bone preservative strategies could reduce the risk of osteoporosis/fractures among ICU survivors, as well as decreasing critical illness mortality.

Evaluation of Bone Metabolism in Critically Ill Patients Using CTx and PINP

Background. Prolonged immobilization, nutritional and vitamin D deficiency, and specific drug administration may lead to significant bone resorption. Methods and Patients. We prospectively evaluated critically ill patients admitted to the ICU for at least 10 days. Demographics, APACHE II, SOFA scores, length of stay (LOS), and drug administration were recorded. Blood collections were performed at baseline and on a weekly basis for five consecutive weeks. Serum levels of PINP, β-CTx, iPTH, and 25(OH)vitamin D were measured at each time-point. Results. We enrolled 28 patients of mean age 67.4 ± 2.3 years, mean APACHE II 22.2 ± 0.9, SOFA 10.1 ± 0.6, and LOS 31.6 ± 5.7 days. Nineteen patients were receiving low molecular weight heparin, 17 nor-epinephrine and low dose hydrocortisone, 18 transfusions, and 3 phenytoin. 25(OH)vitamin D serum levels were very low in all patients at all time-points; iPTH serum levels were increased at baseline tending to normalize on 5th week; β-CTx serum levels were significantly increased compared to baseline on 2nd week (peak values), whereas PINP levels were increased significantly after the 4th week. Conclusions. Our data show that critically ill patients had a pattern of hypovitaminosis D, increased iPTH, hypocalcaemia, and BTMs compatible with altered bone metabolism.

Changes in Bone Mineral Density in the Year after Critical Illness

RATIONALE

Critical illness may be associated with increased bone turnover and loss of bone mineral density (BMD). Prospective evidence describing long-term changes in BMD after critical illness is needed to further define this relationship.

OBJECTIVES

To measure the change in BMD and bone turnover markers (BTMs) in subjects 1 year after critical illness compared with population-based control subjects.

METHODS

We studied adult patients admitted to a tertiary intensive care unit (ICU) who required mechanical ventilation for at least 24 hours. We measured clinical characteristics, BTMs, and BMD during admission and 1 year after ICU discharge. We compared change in BMD to age- and sex-matched control subjects from the Geelong Osteoporosis Study.

MEASUREMENTS AND MAIN RESULTS

Sixty-six patients completed BMD testing. BMD decreased significantly in the year after critical illness at both femoral neck and anterior-posterior spine sites. The annual decrease was significantly greater in the ICU cohort compared with matched control subjects (anterior-posterior spine, -1.59%; 95% confidence interval, -2.18 to -1.01; P < 0.001; femoral neck, -1.20%; 95% confidence interval, -1.69 to -0.70; P < 0.001). There was a significant increase in 10-year fracture risk for major fractures (4.85 ± 5.25 vs. 5.50 ± 5.52; P < 0.001) and hip fractures (1.57 ± 2.40 vs. 1.79 ± 2.69; P = 0.001). The pattern of bone resorption markers was consistent with accelerated bone turnover.

CONCLUSIONS

Critically ill individuals experience a significantly greater decrease in BMD in the year after admission compared with population-based control subjects. Their bone turnover biomarker pattern is consistent with an increased rate of bone loss.

The role of biochemical of bone turnover markers in osteoporosis and metabolic bone disease: a consensus paper of the Belgian Bone Club

The exact role of biochemical markers of bone turnover in the management of metabolic bone diseases remains a topic of controversy. In this consensus paper, the Belgian Bone Club aimed to provide a state of the art on the use of these biomarkers in different clinical or physiological situations like in postmenopausal women, osteoporosis in men, in elderly patients, in patients suffering from bone metastasis, in patients with chronic renal failure, in pregnant or lactating women, in intensive care patients, and in diabetics. We also gave our considerations on the analytical issues linked to the use of these biomarkers, on potential new emerging biomarkers, and on the use of bone turnover biomarkers in the follow-up of patients treated with new drugs for osteoporosis.

INTRAVENOUS PAMIDRONATE IS ASSOCIATED WITH REDUCED MORTALITY IN PATIENTS WITH CHRONIC CRITICAL ILLNESS

OBJECTIVE

Chronic critical illness (CCI), characterized by prolonged mechanical ventilation and tracheostomy, commonly manifests with elevated bone resorption, which has previously been shown to abate after treatment with intravenous (IV) bisphosphonates. Our study assessed the impact of pamidronate administration on clinical outcomes in a CCI cohort.

METHODS

A retrospective case series was performed on 148 patients admitted to The Mount Sinai Hospital Respiratory Care Unit (RCU) from 2009-2010. We identified patients with CCI who did (n = 30) or did not (n = 118) receive IV pamidronate (30 to 90 mg). Both groups included patients with normal and abnormal renal function. Pamidronate was administered for elevated urine or serum N-telopeptide, hypercalciuria, or hypercalcemia.

RESULTS

RCU and 1-year mortality were significantly lower in the pamidronate group (0 and 20%, respectively) compared to nonreceivers (19 and 56%, respectively) (P = .0077 and P = .0004, respectively). After adjusting for differences in baseline creatinine, estimated glomerular filtration rate, and serum calcium, the association with reduced mortality remained significant at 1 year (P = .0132) and with borderline significance for RCU mortality (P = .0911). Creatinine was significantly lower 7 days following pamidronate administration (P = .0025), with no significant difference at 14 days compared to baseline. Pamidronate receivers showed a greater increase in albumin during the RCU stay (2.49 to 3.23 g/dL), compared to nonreceivers (2.43 to 2.64 g/dL) (P = .0007). Pamidronate administration was associated with a significantly reduced rate of hypoglycemia compared to RCU patients not receiving pamidronate (0.09 versus 0.12; P = .0071).

CONCLUSION

Pamidronate use in a CCI population is associated with reduced mortality, lower hypoglycemia rates, improved albumin, and stable renal function.

ABBREVIATIONS

BMI = body mass index CCI = chronic critical illness CI = confidence interval CKD = chronic kidney disease CTx = C-telopeptide eGFR = estimated glomerular filtration rate ICU = intensive care unit IV = intravenous NTx = N-telopeptide PMV = prolonged mechanical ventilation RCU = respiratory care unit.

Phosphorus and calcium: a review for the adult nutrition support clinician

Phosphorus (P) and calcium (Ca) serve vital roles in the human body and are essential components of nutrition support therapy. Regulation of P and regulation of Ca in the body are closely interrelated, and P and Ca homeostasis can be affected by several factors, including disease states, clinical condition, severity of illness, and medications. Nutrition support clinicians must understand these factors to prevent and treat P and Ca disorders in patients receiving nutrition support therapy. This review provides an overview of P and Ca for the adult nutrition support clinician, with some emphasis on the hospitalized inpatient.

The association between critical illness and changes in bone turnover in adults: a systematic review

SUMMARY

Critical illness may lead to altered bone turnover and associated adverse health outcomes. This systematic review found moderate evidence for a positive association between critical illness and increased bone turnover. Prospective cohort studies that identify the extent and risk factors for critical illness related bone loss are required.

INTRODUCTION

Intensive care patients face health issues that extend beyond their critical illness and result in significant morbidity and mortality. Critical illness may result in altered bone turnover due to associated immobilisation, inflammation, exposure to medications that effect bone and calcium metabolism, and endocrine dysfunction. The aim of this study was to synthesise the existing evidence for altered bone turnover in adults admitted to intensive care.

METHODS

A literature search using MEDLINE and EMBASE was performed from 1965 to March 2013. Reviewed studies investigated the relationship between critical illness and evidence of altered bone turnover (bone turnover markers, bone mineral density, or fracture). Studies were rated upon their methodological quality, and a best-evidence synthesis was used to summarise the results.

RESULTS

Four cohort and seven case-control studies were identified for inclusion, of which five studies were rated as being of higher methodological quality. Ten of the studies measured bone turnover markers, and one study fracture rate. Findings were consistent across studies, and best-evidence analysis resulted in a conclusion that moderate evidence exists for an association between critical illness requiring admission to intensive care and altered bone turnover.

CONCLUSION

A positive association between critical illness requiring intensive care admission and bone turnover exists, although data are limited, and the risk factors and the nature of the relationship are not yet understood. Prospective cohort studies that identify risk factors and extent of critical illness related bone turnover changes are required.

Bone ultrasound velocity in pediatric intensive care unit: a pilot study

BACKGROUND

Bone loss has been documented in adults in intensive care wards. Children admitted to pediatric intensive care units (PICU) are also exposed to many potential risk factors for bone loss such as immobilization, catabolic state, and nutritional depletion. Quantitative ultrasound technique that measures speed of sound (SOS) correlates with bone mineral density (BMD) and strength. Herein is a clinical prospective longitudinal, observational pilot study to evaluate early bone changes that occur during the first few days of PICU admission.

METHODS

Children are hospitalized in a pediatric intensive under general anesthesia and muscle paralysis. Bone SOS at the mid-shaft tibia was measured on the first day of hospitalization and on days 2 to 3 thereafter.

RESULTS

Nineteen children were studied. Bone SOS decreased during the first 3 days of hospitalization from 3,297 ± 315 to 3,260 ± 311 m/min (p < 0.05). The decrease was approximately 1% of the original SOS over the first 2 to 3 days of admission.

CONCLUSION

There is a significant decrease in bone strength after 3 days in pediatric patients admitted to an intensive care department. Longitudinal studies of a larger group of children are necessary to determine the clinical meaning of the results and to possibly evaluate preventive approaches.

Low serum 25-hydroxyvitamin D at critical care initiation is associated with increased mortality

OBJECTIVE

We hypothesized that deficiency in 25-hydroxyvitamin D at critical care initiation would be associated with all-cause mortalities.

DESIGN

Two-center observational study.

SETTING

Two teaching hospitals in Boston, MA.

PATIENTS

The study included 1,325 patients, age ≥ 18 yrs, in whom 25-hydroxyvitamin D was measured 7 days before or after critical care initiation between 1998 and 2009.

MEASUREMENTS

25-hydroxyvitamin D was categorized as deficiency in 25-hydroxyvitamin D (≤ 15 ng/mL), insufficiency (16-29 ng/mL), and sufficiency (≥ 30 ng/mL). Logistic regression examined death by days 30, 90, and 365 postcritical care initiation and in-hospital mortality. Adjusted odds ratios were estimated by multivariable logistic regression models.

INTERVENTIONS

None.

KEY RESULTS

25-hydroxyvitamin D deficiency is predictive for short-term and long-term mortality. Thirty days following critical care initiation, patients with 25-hydroxyvitamin D deficiency have an odds ratio for mortality of 1.85 (95% confidence interval 1.15-2.98; p = .01) relative to patients with 25-hydroxyvitamin D sufficiency. 25-hydroxyvitamin D deficiency remains a significant predictor of mortality at 30 days following critical care initiation following multivariable adjustment for age, gender, race, Deyo-Charlson index, sepsis, season, and surgical vs. medical patient type (adjusted odds ratio 1.94; 95% confidence interval 1.18-3.20; p = .01). Results were similarly significant at 90 and 365 days following critical care initiation and for in-hospital mortality. The association between vitamin D and mortality was not modified by sepsis, race, or neighborhood poverty rate, a proxy for socioeconomic status.

CONCLUSION

Deficiency of 25-hydroxyvitamin D at the time of critical care initiation is a significant predictor of all-cause patient mortality in a critically ill patient population.

Vitamin D metabolism and deficiency in critical illness

Vitamin D deficiency is highly prevalent and has been associated with a diverse range of chronic medical conditions in the general population. In contrast, the prevalence, pathogenesis and significance of vitamin D deficiency have received little attention in acute medicine. Vitamin D deficiency is seldom considered and rarely corrected adequately, if at all, in critically ill patients. Recent recognition of the extra-skeletal, pleiotropic actions of vitamin D in immunity, epithelial function and metabolic regulation may underlie the previously under-recognized contribution of vitamin D deficiency to typical co-morbidities in critically ill patients, including sepsis, systemic inflammatory response syndrome and metabolic dysfunction. Improved understanding of vitamin D metabolism and regulation in critical illness may allow therapeutic exploitation of vitamin D to improve outcome in critically ill patients.

Skeletal morbidity among survivors of critical illness

OBJECTIVES

To describe the incident fracture rate in survivors of critical illness and to compare fracture risk with population-matched control subjects.

DESIGN

Retrospective longitudinal case-cohort study.

SETTING

A tertiary adult intensive care unit in Australia.

PATIENTS

All patients ventilated admitted to intensive care and requiring mechanical ventilation for ≥48 hrs between January 1998 and December 2005.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

New fractures were identified in the study population for the postintensive care unit period (intensive care unit discharge to January 2008). The incident fracture rate and age-adjusted fracture risk of the female intensive care unit population were compared with the general population adult females derived from the Geelong Osteoporosis Study. Over the 8-yr period, a total of 739 patients (258 women, 481 men) were identified. After a median follow-up of 3.7 yrs (interquartile range, 2.0-5.9 yrs) for women and 4.0 yrs (interquartile range, 2.1-6.1 yrs) for men, incident fracture rates (95% confidence interval) per 100 patient years were 3.84 (2.58-5.09) for females 2.41 (1.73-3.09) for males. Compared with an age-matched random population-based sample of women, elderly women were at increased risk for sustaining an osteoporosis-related fracture after critical illness (hazard ratio, 1.65; 95% confidence interval, 1.08-2.52; p = .02).

CONCLUSIONS

The increase in fracture risk observed in postintensive care unit older females suggests an association between critical illness and subsequent skeletal morbidity. The explanation for this association is not explored in this study and includes the effects of pre-existing patient factors and/or direct effects of critical illness. Prospective research evaluating risk factors, the relationship between critical illness and bone turnover, the extent and duration of bone loss, and the associated morbidity in this population is warranted.

Nutrition management for the patient requiring prolonged mechanical ventilation

Patients requiring prolonged mechanical ventilation are often medically complex and present with a wide range of pulmonary conditions, including neuromuscular diseases, chronic pulmonary diseases, and chronic critical illness. These patients present the nutrition support professional with many challenges. However, accurate nutrition assessment, timely and effective nutrition interventions, and careful monitoring will help patients meet their medical and nutrition goals.

Association of low serum 25-hydroxyvitamin D levels and mortality in the critically ill

OBJECTIVE

We hypothesized that deficiency in 25-hydroxyvitamin D before hospital admission would be associated with all-cause mortality in the critically ill.

DESIGN

Multicenter observational study of patients treated in medical and surgical intensive care units.

SETTING

A total of 209 medical and surgical intensive care beds in two teaching hospitals in Boston, MA.

PATIENTS

A total of 2399 patients, age ≥ 18 yrs, in whom 25-hydroxyvitamin D was measured before hospitalization between 1998 and 2009.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Preadmission 25-hydroxyvitamin D was categorized as deficiency in 25-hydroxyvitamin D (≤ 15 ng/mL), insufficiency (16-29 ng/mL), and sufficiency (≥ 30 ng/mL). Logistic regression examined death by days 30, 90, and 365 post-intensive care unit admission, in-hospital mortality, and blood culture positivity. Adjusted odds ratios were estimated by multivariable logistic regression models. Preadmission 25-hydroxyvitamin D deficiency is predictive for short-term and long-term mortality. At 30 days following intensive care unit admission, patients with 25-hydroxyvitamin D deficiency have an odds ratio for mortality of 1.69 (95% confidence interval of 1.28-2.23, p < .0001) relative to patients with 25-hydroxyvitamin D sufficiency. 25-Hydroxyvitamin D deficiency remains a significant predictor of mortality at 30 days following intensive care unit admission following multivariable adjustment (adjusted odds ratio of 1.69, 95% confidence interval of 1.26-2.26, p < .0001). At 30 days following intensive care unit admission, patients with 25-hydroxyvitamin D insufficiency have an odds ratio of 1.32 (95% confidence interval of 1.02-1.72, p = .036) and an adjusted odds ratio of 1.36 (95% confidence interval of 1.03-1.79, p = .029) relative to patients with 25-hydroxyvitamin D sufficiency. Results were similar at 90 and 365 days following intensive care unit admission and for in-hospital mortality. In a subgroup analysis of patients who had blood cultures drawn (n = 1160), 25-hydroxyvitamin D deficiency was associated with increased risk of blood culture positivity. Patients with 25-hydroxyvitamin D insufficiency have an odds ratio for blood culture positivity of 1.64 (95% confidence interval of 1.05-2.55, p = .03) relative to patients with 25-hydroxyvitamin D sufficiency, which remains significant following multivariable adjustment (odds ratio of 1.58, 95% confidence interval of 1.01-2.49, p = .048).

CONCLUSION

Deficiency of 25-hydroxyvitamin D before hospital admission is a significant predictor of short- and long-term all-cause patient mortality and blood culture positivity in a critically ill patient population.

Understanding, recognizing, and managing chronic critical illness syndrome

PURPOSE

No evidence-based guidelines exist for the care of patients with chronic critical illness syndrome (CCIS), a growing population of patients being cared for by nurse practitioners (NPs). The purpose of this article is to provide NPs with a beginning physiological framework, allostasis, to guide their understanding and management of patients with CCIS.

DATA SOURCES

Scientific publications, related clinical guidelines.

CONCLUSIONS

Patients with CCIS are a distinct group of critically ill patients whose care needs are different from those of patients who are acutely critically ill. These patients demonstrate widespread tissue and organ damage. The widespread tissue and organ damage results in a syndrome of interrelated elements, which include neuroendocrine problems, severe malnutrition, wounds, infections, bone loss, polyneuropathy and myopathy, delirium and depression, and suffering.

IMPLICATIONS FOR PRACTICE

In caring for patients with CCIS, NPs need to focus on treating the elements of the syndrome as a cohort of interrelated elements and on re-establishing normalcy for the patient.

Bone physiology and therapeutics in chronic critical illness

Modern medical practices allow patients to survive acute insults and be sustained by machinery and medicines for extended periods of time. We define chronic critical illness as a later stage of prolonged critical illness that requires tracheotomy. These patients have persistent elevations of inflammatory cytokines, diminished hypothalamic-pituitary function, hypercatabolism, immobilization, and malnutrition. The measurement of bone turnover markers reveals markedly enhanced osteoclastic bone resorption that is uncoupled from osteoblastic bone formation. We review the mechanisms by which these factors contribute to the metabolic bone disease of chronic critical illness and suggest potential therapeutics.

Chronic critical illness

Although advances in intensive care have enabled more patients to survive an acute critical illness, they also have created a large and growing population of chronically critically ill patients with prolonged dependence on mechanical ventilation and other intensive care therapies. Chronic critical illness is a devastating condition: mortality exceeds that for most malignancies, and functional dependence persists for most survivors. Costs of treating the chronically critically ill in the United States already exceed $20 billion and are increasing. In this article, we describe the constellation of clinical features that characterize chronic critical illness. We discuss the outcomes of this condition including ventilator liberation, mortality, and physical and cognitive function, noting that comparisons among cohorts are complicated by variation in defining criteria and care settings. We also address burdens for families of the chronically critically ill and the difficulties they face in decision-making about continuation of intensive therapies. Epidemiology and resource utilization issues are reviewed to highlight the impact of chronic critical illness on our health care system. Finally, we summarize the best available evidence for managing chronic critical illness, including ventilator weaning, nutritional support, rehabilitation, and palliative care, and emphasize the importance of efforts to prevent the transition from acute to chronic critical illness. As steps forward for the field, we suggest a specific definition of chronic critical illness, advocate for the creation of a research network encompassing a broad range of venues for care, and highlight areas for future study of the comparative effectiveness of different treatment venues and approaches.

Intensive metabolic support: evolution and revolution

OBJECTIVE

To describe a new aspect of critical care termed intensive metabolic support.

METHODS

We performed a MEDLINE search of the English-language literature published between 1995 and 2008 for studies regarding the metabolic stages of critical illness, intensive insulin treatment, and intensive metabolic support in the intensive care unit, and we summarize the clinical data.

RESULTS

Intensive metabolic support is a 3-component model involving metabolic control and intensive insulin therapy, early nutrition support, and nutritional pharmacology aimed at preventing allostatic overload and the development of chronic critical illness. To improve clinical outcome and prevent mortality, intensive metabolic support should start on arrival to the intensive care unit and should end only when patients are in the recovery phase of their illness.

CONCLUSIONS

Intensive metabolic support should be an essential part of the daily treatment strategy in critical care medicine. This will involve a newfound and extensive collaboration between the endocrinologist and the intensivist. We call for well-designed future studies involving implementation of this protocol to decrease the burden of chronic critical illness.

Bisphosphonates and metabolic bone disease in the ICU

PURPOSE OF REVIEW

The purpose of this review is to discuss the elements of critical illness that predispose to rapid and severe bone loss and illustrate how potent nitrogen containing intravenous bisphosphonates can mitigate this potentially serious disease.

RECENT FINDINGS

Recent studies confirm that inflammatory cytokines, immobilization, and hormonal irregularities incite osteoclast-mediated bone resorption. Bisphosphonates are antiresorptive agents and well suited to treat this bone loss. Intravenous bisphosphonates have long been considered safe, but recent evidence has raised concerns in regard to such serious side effects as atrial fibrillation, osteonecrosis of the jaw, and 'frozen bone'.

SUMMARY

Metabolic bone disease in the ICU is potentially a devastating consequence of critical illness. Screening with biochemical markers of bone turnover may allow identification of those most likely to have fracture after ICU discharge. Intravenous bisphosphonates are safe and very effective at preventing osteoporotic fracture in other populations. There is likely a subset of individuals who remain critically ill for a prolonged period of time that may benefit from an intravenous infusion of a potent aminobisphosphonate.

Communication about chronic critical illness

BACKGROUND

Despite poor outcomes, life-sustaining treatments including mechanical ventilation are continued for a large and growing population of patients with chronic critical illness. This may be owing in part to a lack of understanding resulting from inadequate communication between clinicians and patients and families. Our objective was to investigate the informational needs of patients with chronic critical illness and their families and the extent to which these needs are met.

METHODS

In this prospective observational study conducted at 5 adult intensive care units in a large, university-affiliated hospital in New York, New York, 100 patients with chronic critical illness (within 3-7 days of elective tracheotomy for prolonged mechanical ventilation) or surrogates for incapacitated patients were surveyed using an 18-item questionnaire addressing communication about chronic critical illness. Main outcome measures included ratings of importance and reports of whether information was received about questionnaire items.

RESULTS

Among 125 consecutive, eligible patients, 100 (80%) were enrolled; questionnaire respondents included 2 patients and 98 surrogates. For all items, more than 78% of respondents rated the information as important for decision making (>98% for 16 of 18 items). Respondents reported receiving no information for a mean (SD) of 9.0 (3.3) of 18 items, with 95% of respondents reporting not receiving information for approximately one-quarter of the items. Of the subjects rating the item as important, 77 of 96 (80%) and 69 of 74 (93%) reported receiving no information about expected functional status at hospital discharge and prognosis for 1-year survival, respectively.

CONCLUSIONS

Many patients and their families may lack important information for decision making about continuation of treatment in the chronic phase of critical illness. Strategies for effective communication in this clinical context should be investigated and implemented.

Nutrition support and the chronic critical illness syndrome

Critical illness can be viewed as consisting of 4 distinct stages: (1) acute critical illness (ACI), (2) prolonged acute critical illness, (3) chronic critical illness, and (4) recovery. ACI represents the evolutionarily programmed response to a stressor. In ACI, substrate is shunted away from anabolism and toward vital organ support and inflammatory proteins. Nutrition support in this stage is unproven and may ultimately prove detrimental. As critical illness progresses, there is no evolutionary precedent, and man owes his life to modern critical care medicine. It is at this point that nutrition and metabolic support become integral to the care of the patient. This paper (1) delineates and develops the 4 stages of critical illness using current evidence, clinical experience, and new hypotheses; (2) defines the chronic critical illness syndrome (CCIS); and (3) details an approach to the metabolic and nutrition support of the chronically critically ill patient using the metabolic model of critical illness as a guide. It is our hope that this clinical model can generate testable hypotheses that can improve the outcome of this unique population of patients.

Effect of a convenient single 90-mg pamidronate dose on biochemical markers of bone metabolism in patients with acute spinal cord injury

BACKGROUND/OBJECTIVE

To describe the biochemical and adverse effects of a convenient single 90 mg pamidronate dose in patients with acute spinal cord injury (SCI) and compare these effects with those observed in a previous similar study using a 30 mg/d x 3-day pamidronate dosing regimen.

STUDY DESIGN

Retrospective cohort study.

SETTING

University-based rehabilitation center in New York City.

METHODS

A total of 32 patients with SCI were evaluated for biochemical response and adverse events associated with pamidronate therapy. All patients were screened at or near admission for acute rehabilitation, received calcium (1,000 mg daily) and calcitriol (0.25 micrg daily) therapy daily, and on day 4, received a single dose of pamidronate, 90 mg by intravenous infusion, over 4 hours. Serum calcium and phosphate levels were closely monitored, and 2 weeks after pamidronate, biochemical bone markers were re-evaluated.

RESULTS

Responses of biochemical markers of bone resorption (N-telopeptide and 24-hour urinary calcium excretion) to pamidronate 90 mg were consistent with an antiresorptive effect, although less than that observed with a 30 mg/d x 3-day pamidronate dosing regimen. The frequency of hypocalcemia was greater, and hypophosphatemia was less than the 30 mg/d x 3-day pamidronate dosing regimen. Fever was more frequent (78%) with the 90-mg single dose of pamidronate compared with the 30 mg/d x 3-day pamidronate dosing regimen (20%).

CONCLUSIONS

Single-dose pamidronate 90 mg is effective at reducing biochemical markers of bone hyperresorption in patients with acute SCI but is associated with a greater incidence of fever compared with a 30 mg/d x 3-day dosing regimen.

Nutrition and the chronically critically ill patient

PURPOSE OF REVIEW

It has been recently recognized that patients of chronic critical illness (CCI) - those who have stabilized after an acute critical illness but remain dependent on life-support - manifest a distinct set of clinical attributes. This unique patient population is often dismissed as hopeless, with aggressive medical therapies considered futile. In fact, with meticulous care, many CCI patients can be liberated from mechanical ventilation and graduated to a rehabilitation program. The nutritional approach to CCI patients is presented here as part of a comprehensive metabolic program to increase their survival and quality of life.

RECENT FINDINGS

Both theory-driven and data-driven advances to our knowledge of CCI syndrome have appeared in the literature over the past year. Recurrent activation of the immune-neuroendocrine axis may induce allostatic overload in CCI. Experimental studies with hypothalamic releasing factors and intensive insulin therapy demonstrate that mechanisms perpetuating the CCI state can be abrogated. Recent studies and consensus opinions support the use of aggressive nutrition support.

SUMMARY

Nutritional assessment and support of the CCI patient must be implemented upon admission to the respiratory care unit (RCU). Enteral nutrition (EN) with semi-elemental formulas is preferred. Parenteral nutrition is used to supplement EN when necessary. Overfeeding is avoided and tight glycemic control maintained. Diarrhea is aggressively managed. By correcting proximal etiologic events (infection, inflammatory, injuries), avoiding iatrogenic complications and devoting careful attention to nutritional status, CCI patients can potentially overcome their pulmonary compromise and debilitated state, to fully recover.

The symptom burden of chronic critical illness

OBJECTIVE

To assess self-reported symptom burden of chronic critical illness.

DESIGN

Prospective cohort study.

SETTING

Respiratory care unit for treatment of chronically critically ill patients at an academic, tertiary-care, urban medical center.

PATIENTS

Fifty patients who underwent elective tracheotomy and transfer from an adult intensive care unit to the respiratory care unit for weaning from mechanical ventilation.

INTERVENTIONS

Assessment of physical and psychological symptoms through patients' self-reports using a modification of the Condensed Form of the Memorial Symptom Assessment Scale.

MEASUREMENTS AND MAIN RESULTS

We measured self-reported symptom burden, ventilator outcomes, and vital status and functional status at discharge and 3 and 6 months after discharge. Half of the patients were successfully liberated from mechanical ventilation, but most hospital survivors were discharged to skilled nursing facilities and more than half of the cohort was dead at 3 months after discharge. Seventy-two percent (36 of 50) of patients were able to self-report symptoms during the period of respiratory care unit treatment. Among patients responding to symptom assessment, approximately 90% were symptomatic. Forty-four percent of patients reported pain at the highest levels. More than 60% reported psychological symptoms at these levels, and approximately 90% of patients reported severe distress due to difficulty communicating.

CONCLUSIONS

Physical and psychological symptom distress is common and severe among patients receiving treatment for chronic critical illness. The majority of these patients die soon after hospital discharge. Given the level of distress in our study patients and the high mortality rate that we and others have observed, greater attention should be given to relief of pain and other distressing symptoms and to assessment of burdens and benefits of treatment for the chronically critically ill.

Practical aspects of nutritional support for wound-healing patients

Nutrition and metabolic support of acutely and chronically ill patients is an emerging branch of medicine that has direct applicability to wound healing. The occurrence of pressure ulcers is associated with malnutrition, as well as specific micronutrient deficiencies. A comprehensive approach is reviewed that involves nutritional assessment, selection of an appropriate route for nutrition support (enteral versus parenteral), prioritizing nitrogen retention over energy balance in stressed patients, micronutrient management, and incorporation of specialized nutritional pharmacologic interventions.

Endocrine and metabolic issues in the management of the chronically critically ill patient

The metabolic syndrome of chronic critical illness (CCI) consists of multisystem organ dysfunction resulting from the initial acute injury and chronic immune-neuroendocrine axis activation, adult kwashiorkor-like malnutrition, and prolonged immobilization with suppression of the PTH-vitamin D axis and hyper-resorptive metabolic bone disease. CCI patients can also present unique challenges in the management of diabetes mellitus, thyroid and adrenal diseases, electrolyte abnormalities and hypogonadism.

A structure of care for the chronically critically ill

The chronically critically ill (CCI) are complicated, labor-intensive, and costly patients to care for. A defined structure of care with different focuses at the beginning, middle, and end of a care episode may improve their outcomes and resource utilization. This article reviews the prediction of CCI, outlines some unifying processes of care during an episode of chronic critical illness, and explores some of the difficulties in defining consistent goals of care for this patient population.

Immobilization-related hypercalcemia after renal failure in burn injury

OBJECTIVE

To describe a patient with hypercalcemia presumably due to immobilization in the setting of burn injury and acute renal failure.

METHODS

We present a case report of a man who sustained a severe burn injury and then had renal failure and hypercalcemia. An additional series of patients with burns and immobilization was assessed for the presence of hypercalcemia.

RESULTS

In a 43-year-old man with burns on 65% of his body surface area, acute renal failure developed. Renal function failed to return, and he continued to require hemodialysis. Because of the severity and extensiveness of his burns, he remained immobilized. Serum calcium levels were low during the early part of the hospitalization. On the 57th day, generalized tonic-clonic seizures developed, and he was found to have a high ionized calcium level (1.41 mmol/L). Low values were recorded for intact parathyroid hormone (2 pg/mL), 25-hydroxyvitamin D (5 ng/mL), and 1,25-dihydroxyvitamin D (4 pg/mL). Persistent and recurrent hypercalcemia eventually responded to pamidronate and calcitonin. Other than immobilization, we could identify no predisposing factors such as confounding illnesses or medications that could have caused the hypercalcemia. A review of serum ionized calcium levels in 50 consecutive patients admitted to a burn unit and immobilized for at least 20 days failed to reveal any episodes of persistent hypercalcemia.

CONCLUSION

In our patient with burns and renal failure, symptomatic hypercalcemia was most likely attributable to prolonged immobilization. As patients with catastrophic illnesses survive for longer periods, additional problems such as hypercalcemia from immobilization may occur.