Late pulmonary sequela following burns: persistence of hyperprocalcitonemia using a 1-57 amino acid N-terminal flanking peptide assay

Six Months of Exercise Training Improves Ventilatory Responses during Exercise in Adults with Well-Healed Burn Injuries

INTRODUCTION

Pulmonary function is lower after a severe burn injury, which could influence ventilatory responses during exercise. It is unclear whether exercise training improves pulmonary function or ventilatory responses during exercise in adults with well-healed burn injuries. Therefore, we tested the hypothesis that exercise training improves pulmonary function and ventilatory responses during exercise in adults with well-healed burn injuries.

METHODS

Thirty-nine adults (28 with well-healed burn injuries and 11 non-burn-injured controls) completed 6 months of unsupervised, progressive exercise training including endurance, resistance, and high-intensity interval components. Before and after exercise training, we performed comprehensive pulmonary function testing and measured ventilatory responses during cycling exercise. We compared variables using two-way ANOVA (group-time; i.e., preexercise/postexercise training (repeated factor)).

RESULTS

Exercise training did not increase percent predicted spirometry, lung diffusing capacity, or airway resistance measures (time: P ≥ 0.14 for all variables). However, exercise training reduced minute ventilation ( V̇E ; time: P ≤ 0.05 for 50 and 75 W) and the ventilatory equivalent for oxygen ( V̇E /V̇O 2 ; time: P < 0.001 for 75 W) during fixed-load exercise for both groups. The ventilatory equivalent for carbon dioxide ( V̇E /V̇CO 2 ) during exercise at 75 W was reduced after exercise training (time: P = 0.04). The percentage of age-predicted maximum heart rate at the ventilatory threshold was lower in adults with well-healed burn injuries before ( P = 0.002), but not after ( P = 0.22), exercise training. Lastly, exercise training increased V̇E and reduced V̇E /V̇O 2 during maximal exercise (time: P = 0.005 for both variables).

CONCLUSIONS

These novel findings demonstrate that exercise training can improve ventilatory responses during exercise in adults with well-healed burn injuries.

Adults with well-healed burn injuries have lower pulmonary function values decades after injury

Sub-acute (e.g., inhalation injury) and/or acute insults sustained during a severe burn injury impairs pulmonary function. However, previous work has not fully characterized pulmonary function in adults with well-healed burn injuries decades after an injury. Therefore, we tested the hypothesis that adults with well-healed burn injuries have lower pulmonary function years after recovery. Our cohort of adults with well-healed burn-injuries (n = 41) had a lower forced expiratory volume in one second (Burn: 93 ± 16 vs. Control: 103 ± 10%predicted, mean ± SD; d = 0.60, p = 0.04), lower maximal voluntary ventilation (Burn: 84 [71-97] vs. Control: 105 [94-122] %predicted, median [IQR]; d = 0.84, p < 0.01), and a higher specific airway resistance (Burn: 235 ± 80 vs. Control: 179 ± 40%predicted, mean ± SD; d = 0.66, p = 0.02) than non-burned control participants (n = 12). No variables were meaningfully influenced by having a previous inhalation injury (d ≤ 0.44, p ≥ 0.19; 13 of 41 had an inhalation injury), the size of the body surface area burned (R²  ≤ 0.06, p ≥ 0.15; range of 15%-88% body surface area burned), or the time since the burn injury (R²  ≤ 0.04, p ≥ 0.22; range of 2-50 years post-injury). These data suggest that adults with well-healed burn injuries have lower pulmonary function decades after injury. Therefore, future research should examine rehabilitation strategies that could improve pulmonary function among adults with well-healed burn injuries.

Serum procalcitonin as a diagnostic marker of neonatal sepsis

Purpose

We evaluated serum procalcitonin (PCT) as a diagnostic marker of neonatal sepsis, and compared PCT levels with C-reactive protein (CRP) levels.

Methods

We retrospectively reviewed the medical records of 269 neonates with a suspected infection, admitted to Wonkwang University School of Medicine & Hospital between January 2011 and December 2012, for whom PCT and CRP values had been obtained. Neonates were categorized into 4 groups according to infection severity. CRP and PCT values were analyzed and compared, and their effectiveness as diagnostic markers was determined by using receiver operating characteristic (ROC) curve analysis. We also calculated the sensitivity, specificity, and positive, and negative predictive values.

Results

The mean PCT and CRP concentrations were respectively 56.27±81.89 and 71.14±37.17 mg/L in the "confirmed sepsis" group; 15.64±32.64 and 39.23±41.41 mg/L in the "suspected sepsis" group; 9.49±4.30 and 0.97±1.16 mg/L in the "mild infection" group; and 0.21±0.12 and 0.72±0.7 mg/L in the control group. High concentrations indicated greater severity of infection (P<0.001). Five of 18 patients with confirmed sepsis had low PCT levels (<1.0 mg/L) despite high CRP levels. In the ROC analysis, the area under the curve was 0.951 for CRP and 0.803 for PCT. The cutoff concentrations of 0.5 mg/L for PCT and 1.0 mg/L for CRP were optimal for diagnosing neonatal sepsis (sensitivity, 88.29% vs. 100%; specificity, 58.17% vs. 85.66%; positive predictive value, 13.2% vs. 33.3%; negative predictive value, 98.6% vs. 100%, respectively).

Conclusion

PCT is a highly effective early diagnostic marker of neonatal infection. However, it may not be as reliable as CRP.

Procalcitonin as a biomarker of acute lower respiratory tract infections

BACKGROUND

Procalcitonin (PCT) has emerged as a promising 'acute phase' biomarker used for diagnosis of acute bacterial infections of the respiratory tract. The introduction of new sensitive PCT assays has facilitated implementation of a new clinical approach to reduce antibiotic use in acute lower respiratory tract infections (LRTIs), without compromising patient safety.

OBJECTIVE

Current state of knowledge on the clinical usefulness of serum PCT measurements for the evaluation of acute LRTIs is presented herein, together with basic information on available rapid diagnostic tests for PCT measurement.

METHODS

During the literature search the emphasis was on PCT use as a diagnostic, monitoring and prognostic tool for acute LRTIs. The acute LRTIs have been defined as acute bronchitis, acute exacerbations of chronic obstructive pulmonary disease or asthma, and pneumonia. Original studies involving patients with these conditions have been considered, and recent articles documenting interventional trials on PCT use for guidance of antimicrobial treatment in LRTIs have been reviewed in particular.

RESULTS/CONCLUSION

When measured with sensitive and rapid assays, PCT has proved to be a good biomarker for acute bacterial LRTIs, which enables an early diagnosis, facilitates therapeutic decisions, and can inform clinicians about the course of disease and prognosis. PCT can become a particularly suitable tool for implementation in an emergency and acute medical care setting.

Procalcitonin in sepsis and systemic inflammation: a harmful biomarker and a therapeutic target

The worldwide yearly mortality from sepsis is substantial, greater than that of cancer of the lung and breast combined. Moreover, its incidence is increasing, and its response to therapy has not appreciably improved. In this condition, the secretion of procalcitonin (ProCT), the prohormone of calcitonin, is augmented greatly, attaining levels up to thousands of fold of normal. This hypersecretion emanates from multiple tissues throughout the body that are not traditionally viewed as being endocrine. The serum values of ProCT correlate with the severity of sepsis; they recede with its improvement and worsen with exacerbation. Accordingly, as highlighted in this review, serum ProCT has become useful as a biomarker to assist in the diagnosis of sepsis, as well as related infectious or inflammatory conditions. It is also a useful monitor of the clinical course and prognosis, and sensitive and specific assays have been developed for its measurement. Moreover, it has been demonstrated that the administration of ProCT to septic animals greatly increases mortality, and several toxic effects of ProCT have been elucidated by in vitro experimental studies. Antibodies have been developed that neutralize the harmful effects of ProCT, and their use markedly decreases the symptomatology and mortality of animals that harbour a highly virulent sepsis analogous to that occurring in humans. This therapy is facilitated by the long duration of serum ProCT elevation, which allows for a broad window of therapeutic opportunity. An experimental groundwork has been established that suggests a potential applicability of such therapy in septic humans.

Procalcitonin assay in systemic inflammation, infection, and sepsis: clinical utility and limitations

OBJECTIVE

The use of procalcitonin (ProCT) as a marker of several clinical conditions, in particular, systemic inflammation, infection, and sepsis, will be clarified, and its current limitations will be delineated. In particular, the need for a more sensitive assay will be emphasized. For these purposes, the medical literature comprising clinical studies pertaining to the measurement of serum ProCT in various clinical settings was examined.

DATA SOURCE AND SELECTION

A PubMed search (1965 through November 2007) was conducted, including manual cross-referencing. Pertinent complete publications were obtained using the MeSH terms procalcitonin, C-reactive protein, sepsis, and biological markers. Textbook chapters were also read and extracted.

DATA EXTRACTION AND SYNTHESIS

Available clinical and other patient data from these sources were reviewed, including any data relating to precipitating factors, clinical findings, associated illnesses, and patient outcome. Published data concerning sensitivity, specificity, and reproducibility of ProCT assays were reviewed.

CONCLUSIONS

Based on available data, the measurement of serum ProCT has definite utility as a marker of severe systemic inflammation, infection, and sepsis. However, publications concerning its diagnostic and prognostic utility are contradictory. In addition, patient characteristics and clinical settings vary markedly, and the data have been difficult to interpret and often extrapolated inappropriately to clinical usage. Furthermore, attempts at meta-analyses are greatly compromised by the divergent circumstances of reported studies and by the sparsity and different timing of the ProCT assays. Although a high ProCT commonly occurs in infection, it is also elevated in some noninfectious conditions. Thus, the test is not a specific indicator of either infection or sepsis. Moreover, in any individual patient, the precipitating cause of an illness, the clinical milieu, and complicating conditions may render tenuous any reliable estimations of severity or prognosis. It also is apparent that even a febrile septic patient with documented bacteremia may not necessarily have a serum ProCT that is elevated above the limit of functional sensitivity of the assay. In this regard, the most commonly applied assay (i.e., LUMItest) is insufficiently sensitive to detect potentially important mild elevations or trends. Clinical studies with a more sensitive ProCT assay that is capable of rapid and practicable day-to-day monitoring are needed and shortly may be available. In addition, investigations showing that ProCT and its related peptides may have mediator relevance point to the need for evaluating therapeutic countermeasures and studying the pathophysiologic effect of hyperprocalcitonemia in serious infection and sepsis.

Pathobiochemistry and clinical use of procalcitonin

Induction of the protein procalcitonin during infection and inflammation was first described approximately 10 years ago. A large number of publications, primarily clinical studies, demonstrate the increasing use of procalcitonin in modern clinical practice. However, data on the biological function and origin of procalcitonin is scarce. Findings regarding the possible role and source of procalcitonin in sepsis and infection were recently published, and the pathophysiology of the protein has meanwhile been investigated in various experimental models. Procalcitonin obviously has certain biological functions, and it is also known to be specifically induced. Given the hormonal origin of the mature protein and the inflammation-related functions of its propeptides, some investigators suggest that procalcitonin should be referred to as a "hormokine," although its biological functions should be studied in more detail. This review will survey the data now available in recent publications on the induction, production sources, possible biological functions and clinical uses of procalcitonin.

Effect of exercise training on pulmonary function in children with thermal injury

Severe thermal injury in children results in a decrease in pulmonary function (PF) which lasts well into convalescence. Exercise has been used successfully to improve PF in other populations exhibiting a compromised PF such as in chronic obstructive pulmonary disease. Yet, whether exercise training will induce improvements in PF in burned children is presently unknown. We therefore evaluated if an exercise program improved PF in severely burned children (BC). Twenty healthy controls, nonburn children (NB) age 7 to <18 and 31 severely burned children; ages 7 to <18 years old, with greater than 40% of total body surface area burned were enrolled in the study. Burned children were randomized into two groups. One to participate in a 12-week in-hospital physical rehabilitation program supplemented with an exercise-training program (REX, n = 17) and the other nonexercising group (R, n = 14) to participate in a 12-week, home-based physical rehabilitation program without exercise. Pulmonary function tests were performed for all groups at baseline, but only the REX and R groups were tested after 12 weeks of either exercise or no exercise. Baseline PF for the NB group was normal and no differences in PF were found between the R vs REX groups. However, PF was decreased in BC compared to NB children. There was a significant improvement in PF in the REX group. In contrast, PF in the R group remained relatively unchanged. Severely burned children improve PF as a result of an exercise program and such should be a fundamental component of a multidisciplinary outpatient treatment program for victims of thermal injury.

Procalcitonin as an acute phase marker

Procalcitonin is a 14-kDa protein encoded by the Calc-1 gene along with calcitonin and katacalcin. The function and regulation of this protein are quite different from those of the other gene products. Blood concentrations of procalcitonin are increased in systemic inflammation, especially when this is caused by bacterial infection. Studies of its behaviour in patients with bacterial sepsis have led to the proposal that it may be a useful marker of systemic bacterial infection, with greater specificity and sensitivity than acute phase proteins such as C-reactive protein.

Disordered calcium homeostasis of sepsis: association with calcitonin precursors

BACKGROUND

Hypocalcemia and increased serum levels of calcitonin precursors are common in critically ill patients, especially in those with sepsis. We investigated calcium homeostasis in such patients.

PATIENTS AND METHODS

Serum concentrations of total and ionized calcium and known factors influencing or reflecting calcium homeostasis were measured in 101 consecutive patients of a medical intensive care unit. Calcitonin precursor levels were determined using a highly sensitive radioimmunoassay.

RESULTS

Critical illness per se was associated with decreased serum total and ionized calcium levels, which correlated with the severity of the underlying disease as measured by the APACHE II score. In addition, total and ionized hypocalcemia was more pronounced with increasing severity of infection (P < 0.02), and occurred in parallel with a marked increase of calcitonin precursors (P < 0.001). Mature calcitonin levels, however, remained normal. Changes of serum ionized calcium concentrations from admission to discharge correlated significantly with changes in the serum calcitonin precursor concentration (r2 = - 0.14, P < 0.001). Circulating vitamin D levels, parathyroid hormone levels and other markers reflecting calcium homeostasis did not correlate with the severity of infection.

CONCLUSIONS

In critically ill patients with sepsis, markedly elevated circulating calcitonin precursors might play a role in the development of the pronounced hypocalcemia. The specific calcitonin precursor(s) responsible for this effect and the pathophysiological mechanism remain to be elucidated.

Calcitonin precursors are reliable markers of sepsis in a medical intensive care unit

OBJECTIVE

The diagnosis of infection in critically ill patients is challenging because traditional markers of infection are often misleading. For example, serum concentrations of calcitonin precursors are increased in patients with infections. However, their predictive accuracy for the diagnosis of sepsis in unselected patients in a medical intensive care unit (ICU) is unknown. Therefore, we compared the usefulness of serum concentrations of calcitonin precursors, C-reactive protein, interleukin-6, and lactate for the diagnosis of sepsis in consecutive patients suffering from a broad range of diseases with an anticipated stay of > or =24 hrs in a medical ICU.

DESIGN

Prospective cohort study.

SETTING

Medical intensive care unit in a university medical center.

PATIENTS

101 consecutive critically ill patients.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected at various time points during the course of the disease. Systemic inflammatory response syndrome, sepsis, severe sepsis, and septic shock were diagnosed according to standardized criteria, and patients were reclassified daily without prior knowledge of the serum concentrations of calcitonin precursors or interleukin-6. At admission, 99% of the patients had systemic inflammatory response syndrome, 53% had sepsis, and 5% developed sepsis during their stay in the ICU. Calcitonin precursors, C-reactive protein, interleukin-6, and lactate levels increased with the severity of infection (p < .01, one-way analysis of variance). In a receiver operating characteristic curve analysis, calcitonin precursors were found to be the most reliable laboratory variable for the diagnosis of sepsis as compared with C-reactive protein, interleukin-6, and lactate (p < .01, for each comparison). Calcitonin precursor concentrations of >1 ng/mL had sensitivity of 89% and specificity of 94% for the diagnosis of sepsis. High serum concentrations of calcitonin precursors were associated with poor prognosis (p = .01).

CONCLUSIONS

In a medical ICU, serum calcitonin precursor concentrations are more sensitive and are specific markers of sepsis as compared with serum C-reactive protein, interleukin-6, and lactate levels.

Usefulness of procalcitonin for differentiation between activity of systemic autoimmune disease (systemic lupus erythematosus/systemic antineutrophil cytoplasmic antibody-associated vasculitis) and invasive bacterial infection

OBJECTIVE

To investigate whether the determination of serum procalcitonin (PCT) in systemic autoimmune disease will help to discriminate invasive infection from highly active underlying disease.

METHODS

Three hundred ninety-seven serum samples, from 18 patients with systemic lupus erythematosus (SLE) and 35 patients with systemic antineutrophil cytoplasmic antibody-associated vasculitis (AAV), were analyzed. Clinical disease activity was assessed by the Systemic Lupus Activity Measure in SLE patients and by the Birmingham Vasculitis Activity Score in AAV patients. Procalcitonin concentrations were determined in parallel with concentrations of neopterin, interleukin-6 (IL-6), and C-reactive protein (CRP). Additionally, serum creatinine values were obtained.

RESULTS

In 321 of the 324 samples from the 42 patients with autoimmune disease but without systemic infection, serum PCT levels were within the normal range (i.e., <0.5 ng/ml), whereas the values for neopterin, IL-6, and CRP were elevated in patients with active underlying disease. All 16 systemic infections occurred in 11 patients with AAV, and were associated with PCT levels that were markedly elevated, to a mean +/- SD of 1.93 +/- 1.19 ng/ml. No correlation between the degree of renal impairment and PCT concentrations was seen.

CONCLUSION

PCT may serve as a useful marker for the detection of systemic bacterial infection in patients with systemic autoimmune disease.

Usefulness of procalcitonin for differentiation between activity of systemic autoimmune disease (systemic lupus erythematosus/systemic antineutrophil cytoplasmic antibody-associated vasculitis) and invasive bacterial infection

OBJECTIVE

To investigate whether the determination of serum procalcitonin (PCT) in systemic autoimmune disease will help to discriminate invasive infection from highly active underlying disease.

METHODS

Three hundred ninety-seven serum samples, from 18 patients with systemic lupus erythematosus (SLE) and 35 patients with systemic antineutrophil cytoplasmic antibody-associated vasculitis (AAV), were analyzed. Clinical disease activity was assessed by the Systemic Lupus Activity Measure in SLE patients and by the Birmingham Vasculitis Activity Score in AAV patients. Procalcitonin concentrations were determined in parallel with concentrations of neopterin, interleukin-6 (IL-6), and C-reactive protein (CRP). Additionally, serum creatinine values were obtained.

RESULTS

In 321 of the 324 samples from the 42 patients with autoimmune disease but without systemic infection, serum PCT levels were within the normal range (i.e., <0.5 ng/ml), whereas the values for neopterin, IL-6, and CRP were elevated in patients with active underlying disease. All 16 systemic infections occurred in 11 patients with AAV, and were associated with PCT levels that were markedly elevated, to a mean +/- SD of 1.93 +/- 1.19 ng/ml. No correlation between the degree of renal impairment and PCT concentrations was seen.

CONCLUSION

PCT may serve as a useful marker for the detection of systemic bacterial infection in patients with systemic autoimmune disease.

The complexities of managing severe burns with associated trauma

A high incidence of severe inhalation injuries can be expected in the combined injury patient. The initial management remains attention to the ATLS priorities of airway, breathing, and circulation, with prompt and safe transfer to a regional center of excellence. The treatment of either the burn or the associated injuries may be compromised by their combined presence, and a team approach is essential to their optimal management. Circulatory management goals based on oxygen consumption and delivery allow greater understanding and control of the physiologic demands placed on the patient by the disease process. The management of inhalation injury and ARDS is at an exciting turning point in history, and we now have in hand and use many techniques that allow salvage of these mortal conditions. Pain management is essential to humane care and requires frequent assessment and patient control to be effective. Rehabilitation of the burn and trauma patient starts on the day of injury and requires team dedication to the areas of greatest morbidity early in the planning of surgical priorities and physical therapy.

Pneumonitis-associated hyperprocalcitoninemia

Elevated serum levels of the prohormone of calcitonin (CT), procalcitonin (ProCT), have been documented in illnesses such as inhalational burn injury, in several sepsis syndromes, and in endotoxemia. In this study, we measured and characterized the circulating precursor forms of CT during the course of infectious pneumonitis. The initial (mean +/- SEM) serum total multiform CT level in 12 patients with acute infectious pneumonia was 1,019 +/- 430 pg/mL. In comparison, the mean level of total CT for 19 age-matched control patients without lung disease was 32 +/- 6 pg/mL (P < 0.001). The mean serum total CT level on initial examination was greater in the 6 patients with bacterial isolates, at 1,793 +/- 752 pg/mL, than in those with nonbacterial infectious pneumonia, at 242 +/- 109 pg/mL (P = 0.018). After admission to the hospital, patients' serum total CT progressively declined concomitantly with the clinical resolution of the pneumonia; at discharge, mean serum level was 121 +/- 34 pg/mL. On discharge, the patients who had persistent radiographic abnormalities had significantly higher levels than did those who had complete resolution. Both the mean serum calcium and phosphate were significantly lower at the initial time of study than at discharge (P < 0.002 and P < 0.0004, respectively). Gel filtration chromatography of sera obtained during the acute pneumonitis phase revealed increased levels of precursor forms of CT, including ProCT; these levels diminished with clinical resolution. In an additional three patients, the serum total CT increased very rapidly after aspiration (within 6 to 12 hours); the peak levels were several times greater than the upper limits of normal. In these patients, the principal serum CT components were ProCT and other precursor forms. These results show that both infectious and aspiration pneumonitis are associated with a rapid increase in circulating ProCT and other precursor forms of CT.