Serum free cortisol index,free cortisol,and total cortisol in critically ill children

Background  In critical illness, serum total cortisol (TC) may not adequately reflect adrenal function because of reduced cortisol-binding globulin (CBG). Aim  To evaluate adrenal function of critically ill children, using free cortisol index (FCI), calculated free cortisol (cFC), and TC levels. Methods  Thirty-two critically ill and 36 healthy children were included. All children underwent the 1 μg cosyntropin test. TC and CBG levels were measured. Basal and peak TC, FCI, and cFC were determined. Results  Basal and peak TC, FCI, and cFC of critically ill children were significantly higher than those of the controls. Compared with TC, both basal and peak FCI and cFC of the patients were higher than those of controls to a greater degree. Use of FCI or cFC to diagnose adrenal insufficiency (AI) reduced the frequency of diagnosis of AI by 50%. Conclusion  FCI and cFC better reflect the dynamic changes of adrenal function of critically ill children.     

Determining relevant cortisol concentrations in critically ill patients

The importance of adrenal function to survival in critically ill patients has been established; however, identifying the best method to diagnose adrenal insufficiency has been problematic. Multiple methods of determining adrenal function have been developed, each with its advantages and disadvantages. Serum-free cortisol levels are probably the most accurate, although obtaining this result is technically demanding. Cohen and colleagues investigated the feasibility of measuring tissue cortisol levels in burn patients and whether tissue cortisol levels could be used as a surrogate for plasma-free cortisol levels.     

Initial ventilator settings for critically ill patients

The lung-protective mechanical ventilation strategy has been standard practice for management of acute respiratory distress syndrome (ARDS) for more than a decade. Observational data, small randomized studies and two recent systematic reviews suggest that lung protective ventilation is both safe and potentially beneficial in patients who do not have ARDS at the onset of mechanical ventilation. Principles of lung-protective ventilation include: a) prevention of volutrauma (tidal volume 4 to 8 ml/kg predicted body weight with plateau pressure <30 cmH₂O); b) prevention of atelectasis (positive end-expiratory pressure ≥5 cmH₂O, as needed recruitment maneuvers); c) adequate ventilation (respiratory rate 20 to 35 breaths per minute); and d) prevention of hyperoxia (titrate inspired oxygen concentration to peripheral oxygen saturation (SpO₂) levels of 88 to 95%). Most patients tolerate lung protective mechanical ventilation well without the need for excessive sedation. Patients with a stiff chest wall may tolerate higher plateau pressure targets (approximately 35 cmH₂O) while those with severe ARDS and ventilator asynchrony may require a short-term neuromuscular blockade. Given the difficulty in timely identification of patients with or at risk of ARDS and both the safety and potential benefit in patients without ARDS, lung-protective mechanical ventilation is recommended as an initial approach to mechanical ventilation in both perioperative and critical care settings.In the previous issue of Critical Care, Fuller and colleagues [1] report the results of a systematic review on the use of lung protective (low tidal volume) mechanical ventilation in patients without acute respiratory distress syndrome (ARDS) at the onset of mechanical ventilation.Introduction of positive pressure ventilation during a polio epidemic in 1952 resulted in a large reduction of mortality in patients with respiratory failure (87% to less than 15%) and marked the birth of modern intensive care medicine [2].Better understanding of the effects of positive pressure ventilation on respiratory physiology and mechanics has led to an appreciation of potential side effects of positive pressure ventilation, in particular ventilator-associated lung injury [3]. The key determinants of ventilator-associated lung injury are cyclic alveolar distension (volutrauma) and recruitment/derecruitment (atelectrauma), the size of available lung (''baby lung''), with an additional contribution from preexisting sepsis, vascular pressures, respiratory rate and inspiratory flow [3]. Avoiding high tidal volume ventilation is the only intervention with convincing survival benefit in patients with ARDS [4]. More recently, observational studies and a randomized clinical trial suggested a benefit of avoiding conventional high tidal volume ventilation in all critically ill patients [5,6].The systematic review by Fuller and colleagues [1] highlights the importance of the low tidal volume ventilation strategy in patients without ARDS at the onset of mechanical ventilation. The results from 8 out of 13 studies included in the final analysis of this systematic review show that lower tidal volumes at initiation of mechanical ventilation reduce progression to ARDS. Similar findings were reported in another recent systematic review that combined observational studies and clinical trials in both ICUs and perioperative settings [7]. Neither of these systematic reviews raised concerns about the safety of low tidal volume ventilation in patients without ARDS.Given the difficulty of identifying patients with ARDS in a timely fashion and both the safety and potential benefit of low tidal volume ventilation in patients without ARDS, the question arises whether conventional high tidal volume ventilation should ever be used in critical care or perioperative settings [8,9].High tidal volume ventilation was recommended in operating rooms in the early 1970s to prevent atelectasis [10]. However, later studies did not support this approach and the focus has shifted towards the role of positive end-expiratory pressure, recruitment maneuvers, and the avoidance of a high fraction of inspired O₂ (FiO₂) as safer and more effective ways to prevent atelectasis than high tidal volume [11,12].The second concern with regards to low tidal volume ventilation is the increase of the carbon dioxide partial pressure (PCO₂), but acidosis is usually easily corrected by increasing respiratory rate except in patients with severe ARDS, where permissive hypercapnia may actually be desirable [13]. Another concern regarding low tidal volume ventilation is the potential increase in the need for sedation [14]. However, there is little evidence to support this claim, particularly in patients without ARDS [15].Although limited, the current evidence, including the current report by Fuller and colleagues [1], suggests that the risk/benefit ratio of low tidal volume ventilation in patients with or without ARDS is on the side of benefit. In Figure ​Figure11 we provide a pragmatic approach to lung protective mechanical ventilation in patients with and without ARDS.Open in a separate windowFigure 1How to set the ventilator in perioperative and critical care settings. ARDS, acute respiratory distress syndrome; EtCO₂, end-tidal carbon dioxide; FiO₂, fraction of inspired O₂; PBW, predicted body weight; PEEP, positive end expiratory pressure; PO₂, oxygen partial pressure; SpO₂, peripheral oxygen saturation.     

警惕危重病儿的低钙血症——附57例报告

１引言 危重病儿的低钙血症,往往掩盖原发病的症状和体征,使临床表现复杂化而直接影响原发病的治疗。本文将１９９６年９月至１９９８年８月收治的无佝偻病危重病儿的低钙血症５７例分析报告如下。２ 临床资料２．１一般资料 ５７例均为住院病儿,其中男３９例,女１８例,年龄：１岁以内３７例,１．１岁至５岁１２例; ５．１岁至 １３岁８例。原发病：重症肠炎２２例,重症肺炎１７例,急性肾功能衰竭８例,晚发性维生素Ｋ缺乏致颅内出血５例（５例均先抽搐后出现脑出血症状）,败血症２例,坏死性肠炎并中毒性休克１例,过敏性紫癜并…     

Early hyperlactataemia in critically ill children

Objective: To examine the relationships between early hyperlactataemia, acidosis, organ failure, and mortality in children admitted to intensive care.¶Design: Prospective observational study. Children with lactate levels > 2 mmol/l were eligible for enrolment. Post-operative patients and those with inherited metabolic disease were excluded. Seven hundred and five children admitted to intensive care were screened, and 50 children with hyperlactataemia (incidence 7 %), aged 20.3 months (0.1–191) were enrolled and followed up. The Paediatric Risk of Mortality (PRISM) score, Multiorgan System Failure (MOSF) score, length of ICU stay, and outcome were recorded. Data were collected for lactate (mmol/l), pH, and base excess (BE) until 24 h after admission. Data are reported as median (range) and were analysed by the Mann-Whitney, Fisher's Exact, and Kruskal-Wallis tests, and chi-squared test for trend.¶Results: Overall mortality in the screening group was 70/705 (10 %). In the study group (n = 50) median PRISM score was 19 (4–49), median MOSF score 2 (1–4), and observed mortality 32/50 (64 %). Median duration of ICU stay was 6 days (2–32) in survivors, and median time until death 3 days (0–13) in nonsurvivors. Eleven nonsurvivors (34 %) died within 24 h. In the screening group, hyperlactataemia on admission identified mortality with likelihood ratio = 15. In the study group, neither the admission lactate (3.8 vs 4.6 mmol/l, P = 0.27), pH (7.32 vs 7.30, P = 0.6), nor BE (–7.5 vs –8, P = 0.45) differed significantly between survivors and nonsurvivors. Neither the admission nor peak lactate increased with increasing MOSF score (P = 0.5 and 0.54). The median peak lactate level was 5 mmol/l (2–9.3) in survivors compared to 6.8 mmol/l (2.3–22) in nonsurvivors (P = 0.02), and the cumulative average lactate level was 2.4 mmol/l (1–4.9) in survivors, compared to 4.5 mmol/l (1.6–21) in nonsurvivors (P = 0.0003). Persistent hyperlactataemia 24 h after admission identified mortality with likelihood ratio = 7.¶Conclusion: Hyperlactataemia on admission to intensive care is associated with a high mortality in children. Nonsurvivors within this group may be distinguished by the peak lactate level, or by persistent hyperlactataemia after 24 h of treatment.     

Supporting families of critically ill children

• ? Having a critically ill child can be a heartbreaking experience. The sudden transformation of a healthy child to a critically ill or injured child causes parents to undergo feelings of pain and shock.
• ? Parents with a critically ill child are in acute need of support and intervention by caregivers.
• ? This article describes a parents' support group, conducted as part of a nursing programme student experience, in a pediatric critical-care unit. This experience provides information concerning the group that others may wish to replicate.

     

Hypermetabolism syndrome in critically ill children

The paper focuses on the developmental mechanisms and triggers of hypermetabolism, by describing the specific features of pathophysiological reactions occurring in the child's body. It also shows the leading role of artificial therapeutic feeding included into the multimodality therapy of children under stresses in restoring plastic and energy demands and in preventing the development of multiple organ dysfunction.     

Energy expenditure in critically ill children

OBJECTIVES: To measure energy expenditure in critically ill children and compare it with the energy expenditure predicted by recommended formulas, and relate the measured energy expenditure to nutritional and clinical indices. DESIGN: A prospective, clinical study. SETTING: Tertiary care pediatric intensive care unit in a university children's hospital. PATIENTS: A total of 37 patients with critical illness who were mechanically ventilated for > or =24 hrs were studied. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Chronic protein-energy malnutrition (CPEM) and acute protein-energy malnutrition were defined by the Waterlow's stages and fat and protein stores were classified as defined by Frisancho, Ryan, and Martinez. Severity of illness was assessed by the Pediatric Risk of Mortality Score, the Therapeutic Intervention Scoring System, and indices of organ failure. Oxygen consumption, carbon dioxide production, and the respiratory quotient were measured by indirect calorimetry, and energy expenditure (MEE) was calculated using the modified Weir formula. Resting energy expenditure (PBMR), predicted energy expenditure, and caloric intake were calculated using recommended formulas. A total of 77 measurements were made in 37 children. MEE was significantly lower than PBMR as estimated by all equations except the Talbot equations. MEE was significantly lower than predicted energy expenditure and the recommended daily allowances. On the first day, the MEE/PBMR ratio was <0.9 in 56.8%, 0.9-1.1 in 21.6%, and >1.1 in 21.6% of patients. MEE did not differ significantly among disease groups or between medical and surgical patients. There was no difference in MEE with or without neuromuscular blockade. MEE was lower in the presence of multiple organ system failure (MOSF) (1019 + 166 kcal/m2 without MOSF vs. 862 + 241 with MOSF; p = .025). A total of 21% had CPEM and 8.1% had acute protein-energy malnutrition. Multivariate stepwise regression analysis showed that the protein intake, midarm muscle area, midarm fat area, the use of vasoactive agents, and sedation correlated with MEE (p < .05). With CPEM, MEE was correlated to the severity of illness (p < .05). Patients at risk for protein stores depletion (midarm muscle areas 1 and 2) had a higher incidence of MOSF compared with nutritionally normal children (p < .05), whereas patients with fat stores depletion (midarm fat area 2) had a higher probability of death (50% vs. 6%, respectively). CONCLUSIONS: Recommended daily allowances and energy expenditure predicted by using a stress-related correction to the resting energy expenditure grossly overestimate MEE. MEE is close to PBMR and in many patients, it is lower than PBMR. MEE that is lower than PBMR is associated with a higher morbidity. Nutritional repletion should thus be based on MEE to avoid the problems of over- or underfeeding.     

危重症患儿甲状腺功能测定及其意义

为进一步研究危重症患儿垂体甲状腺功能与疾病预后关系，检测３１例重危症患儿血清甲状腺激素水平并与２０例健康儿童作对照观察。结果：重危症患儿低三碘甲腺原氨酸（Ｔ３）和（或）低甲状腺素（Ｔ４）者２８例（８７．５％），以低Ｔ３发生率最高。６例出现低Ｔ３伴低Ｔ４者中有５例死亡。重危症患儿死亡组Ｔ４（３８．１４±８．４８ｎｍｏｌ／Ｌ）明显低于存活组（８２．５５±３７．８６ｎｍｏｌ／Ｌ）。认为：检测重危患儿血清甲状腺激素对正确判断甲状腺功能及估计疾病预后有一定价值     

Pulse oximetry in critically ill children

To confirm the clinical applicability of a commercial pulse oximeter, we compared arterial hemoglobin saturation values determined by in-vitro oximetry and pulse oximetry in 15 critically ill children. One hundred ninety-two paired hemoglobin saturations were determined by both noninvasive pulse oximetry and direct measurement ot arterial blood samples. The correlation between these two methods of measurement was statistically significant (r = 0.895;p < 0.001). The mean percentage difference between the two measurements was 1.8%. Pulse oximetry was found to be safe and less cumbersome than other methods of monitoring arterial oxygen content. Overall, pulse oximetry was precise and provided a clinically satisfactory noninvasive method tor continuously monitoring arterial hemoglobin saturation in critically ill children.     

Cardiac troponin elevations among critically ill patients

PURPOSE OF THE REVIEW: Elevated levels of cardiac troponins, indicative of the presence of cardiac injury, have been reported in critically ill patients. In this review, the incidence, significance, and clinical relevance of elevated troponin levels among this group of patients will be discussed. RECENT FINDINGS: It has been shown that elevated cardiac troponin levels can be present among critically ill septic patients without evidence of myocardial ischemia. Recent studies show that elevated troponin levels are also present in a diverse group of critically ill patients without sepsis or septic shock. In addition, several but not all studies show that the mortality rate of troponin-positive patients is significantly higher compared with troponin-negative patients. SUMMARY: Elevated troponin levels are not only present in patients suffering from acute coronary syndromes but can also be present in critically ill patients. Even minor elevations are specific for myocardial injury. However, every elevated troponin level in the critically ill patient should not be rigorously diagnosed or treated as a myocardial infarction.     

Hypocalcemia and hypercalcitoninemia in critically ill children

To study Ca metabolism in critically ill children, we measured ionized Ca (Ca2+), parathyroid hormone (PTH), calcitonin, 25 hydroxycholecalciferol (25[OH] D3), 1-25 dihydroxycholecalciferol (1-25[OH]2D3, and gastrin levels in critically ill children and in healthy controls. Patients were considered hypocalcemic if Ca2+ was less than 1.1 mmol/L. Six (14%) of 45 patients were hypocalcemic. Five hypocalcemic patients were studied and were found to have higher calcitonin levels than normocalcemic patients and healthy controls and higher PTH levels than healthy controls. 25(OH)D3 and 1-25(OH)2D3 were not significantly different in the three groups of patients. Gastrin levels were low in critically ill patients, whether or not they were hypocalcemic. We conclude that hypocalcemia occurs frequently in critically ill children. It is associated with raised levels of calcitonin and PTH. The mechanism for the increase in calcitonin is unknown.     

HDL-cholesterol level and cortisol response to synacthen in critically ill patients

Objective To explore the relationship between cholesterol levels and the adrenal cortisol response to synacthen in critically ill patients.Design Prospective observational study.Patients Critically ill patients with multiple organ dysfunction syndrome (MODS) with possible adrenal dysfunction defined as unexplained hypotension, ongoing inotropic support, unexplained fever, unexplained hyponatraemia or a combination of these symptoms.Measurements HDL-cholesterol levels (HDL), total cholesterol levels (TC), and triglycerides (TG) before administration of synacthen. LDL-cholesterol was calculated using the Friedewald formula. Basal cortisol and response to 250 g synacthen intravenously was measured. A cortisol rise of 0.25 mol/l in a 30-min or 60-min blood sample after synacthen infusion was defined as a proper adrenal response.Results Patients with a proper response to synacthen showed higher HDL-cholesterol levels than patients without that response (P=0.02). Severity of disease as measured by APACHE II or SOFA was not a confounder. LDL-cholesterol levels were extremely low in both responders and non-responders and were not associated with the absolute rise in cortisol. In linear and logistic regression analysis HDL-cholesterol was the sole predictor of cortisol response.Conclusions Adrenal cortisol response to a classic 250-g synacthen test relates in critically ill patients to HDL-cholesterol levels. LDL and TC levels did not show such a relation. These findings are in concordance with known biochemical pathways of cortisol production.     

Monitoring of critically ill infants and children

The strategies for monitoring infants and children in the intensive care setting differ from the strategies used to monitor adults. This article highlights the physiologic differences between infants and children and adults that affect these methods. The technical aspects of monitoring infants and children are also discussed.     

Withdrawal from lorazepam in critically ill children

BACKGROUND: Sedatives are used in critically ill children to facilitate mechanical ventilation. Although tolerance and withdrawal are associated with use of sedatives, information about withdrawal from benzodiazepines in children is limited. OBJECTIVE: To document the occurrence of lorazepam withdrawal in critically ill children and identify predictors for the development of withdrawal. METHODS: This prospective, investigational, open-label study enrolled pediatric patients receiving a continuous infusion of lorazepam for at least 72 hours. The lorazepam dosage was tapered in a uniform fashion over 6 days by decreasing the total daily dose by 50% every other day on 3 occasions; it was then discontinued. The occurrence of withdrawal from lorazepam was determined by pediatric intensive care unit attending physicians based on clinical judgment. Patients were assessed for withdrawal twice daily beginning 48 hours after the initiation of the lorazepam taper. Assessments were continued for 72 hours after lorazepam discontinuation or until the patient experienced withdrawal, whichever came first. Patient demographic, sedative dosing, and lorazepam serum concentration data were collected to identify risk factors for withdrawal. RESULTS: Twenty-nine patients completed the study. They received lorazepam for a median duration of about 21 days, and withdrawal occurred in 7 patients. There were no significant differences in demographic variables, lorazepam dosage or other sedative therapy, or lorazepam serum concentrations between patients with withdrawal and those without withdrawal. No predictors of withdrawal were identified. CONCLUSIONS: Withdrawal occurred in 24% of critically ill children receiving long-term sedation from lorazepam. Risk factors for withdrawal are unknown.     

Needs of parents of critically ill children

When a child becomes critically ill, stable patterns of parental routines are changed. Although the resulting stress on parents has long been recognized by clinicians, only recently has research addressed parental needs during a child's illness.     

Arterial thromboembolic complications in critically ill children

PURPOSE: To evaluate incidence and characteristics of arterial thromboembolic complications in critically ill children. MATERIALS AND METHODS: Hospital records of all consecutive patients with arterial thromboembolic events (ATEs) occurring in the pediatric intensive care unit (PICU) from January 1997 to August 2001 were reviewed. Data collected included demographics and location, treatment modalities and outcome of ATEs. RESULTS: Fifty-four ATEs in 51 children (median age, 14 days) were identified, reflecting an incidence of 1.2% of all PICU patients. Arterial thromboembolic events were located in peripheral arteries in 52 (96%) cases and were associated with indwelling arterial catheters (n=26) or cardiac catheterization (n=26). The remaining 2 ATEs were located in the left ventricle and cerebral arteries, respectively. Therapy consisted of heparin (n=51), thrombolysis (n=22), oral anticoagulation (n=12), and aspirin (n=34). Complete resolution was noted in 33 (70%), partial resolution in 10 (21%), and no resolution in 4 (8.5%) cases. Bleeding complications occurred in 1 patient treated with heparin and in 12 (54%) of the 22 patients receiving thrombolytic therapy. CONCLUSIONS: Arterial thromboembolic events are frequent complications of PICU, particularly affecting neonates, and mostly associated with catheters. Studies to determine safe and effective prophylactic and treatment modalities of ATEs in children are required.