[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"health-study-detail:100654441":3},{"organization":4,"outcomesModule":7,"designInfo":26,"detailedDescription":29,"studyPopulation":30,"armGroups":31,"interventions":37,"overallOfficials":25,"centralContacts":43,"locations":25,"responsibleParty":49,"collaborators":25,"id":53,"slug":54,"hasResults":55,"nctId":56,"briefTitle":57,"officialTitle":58,"acronym":59,"eligibilityCriteria":60,"healthyVolunteers":55,"sex":61,"minAge":62,"maxAge":25,"enrollmentInfo":63,"targetDuration":25,"studyType":66,"phases":25,"briefSummary":67,"conditions":68,"keywords":72,"overallStatus":83,"whyStopped":25,"lastUpdateSubmitDate":84,"lastUpdatePostDateStruct":85,"startDateStruct":88,"completionDateStruct":90,"leadSponsor":92,"locationsCount":25},{"fullName":5,"class":6},"Vastra Gotaland Region","OTHER_GOV",{"primaryOutcomes":8,"secondaryOutcomes":13,"otherOutcomes":25},[9],{"measure":10,"description":11,"timeFrame":12},"Within-Participant Regression Coefficient for Respiratory Quotient Versus Serum Phosphate Concentration","Respiratory quotient (RQ) will be calculated from indirect calorimetry as VCO2\u002FVO2, and serum phosphate will be measured in mmol\u002FL. The primary outcome will be the within-participant regression coefficient describing the change in RQ associated with a 0.1 mmol\u002FL change in serum phosphate concentration, estimated using a linear mixed-effects model with participant as a random effect. The model will account for repeated measurements and prespecified covariates including energy intake, carbohydrate intake, insulin treatment, PaCO2, and body temperature.","Daily on study days 1-5, with an additional measurement on day 7 when feasible",[14,18,21],{"measure":15,"description":16,"timeFrame":17},"Sensitivity of NICE Refeeding Risk Criteria for Prespecified Metabolic Changes","Participants will be classified as being at risk or not at risk of refeeding syndrome according to NICE criteria at initiation of nutritional therapy. Sensitivity will be calculated as the proportion of participants who develop the prespecified metabolic pattern and who were classified as at risk according to NICE criteria at baseline.","From initiation of nutrition through study day 5, with follow-up through day 7 when available",{"measure":19,"description":20,"timeFrame":17},"Specificity of NICE Refeeding Risk Criteria for Prespecified Metabolic Changes","Participants will be classified as being at risk or not at risk of refeeding syndrome according to NICE criteria at initiation of nutritional therapy. Specificity will be calculated as the proportion of participants who do not develop the prespecified metabolic pattern and who were correctly classified as not at risk according to NICE criteria at baseline. The prespecified metabolic pattern is defined as respiratory quotient (RQ) ≥0.90 together with a decrease in serum phosphate of at least 0.16 mmol\u002FL during follow-up.",{"measure":22,"description":23,"timeFrame":24},"Number of Participants With RQ ≥0.90 and Serum Phosphate Decrease ≥0.16 mmol\u002FL","The number and proportion of participants who develop both a respiratory quotient (RQ) ≥0.90 and a decrease in serum phosphate of at least 0.16 mmol\u002FL during follow-up will be reported. The timing of the two changes relative to each other will also be described.","Daily during study days 1-5, with an additional assessment on day 7 when feasible",null,{"allocation":25,"interventionModel":25,"interventionModelDescription":25,"primaryPurpose":25,"observationalModel":27,"timePerspective":28,"maskingInfo":25},"COHORT","PROSPECTIVE","Indirect calorimetry (IC) provides measurements of oxygen consumption (VO2) and carbon dioxide production (VCO2), allowing calculation of respiratory quotient (RQ) and resting energy expenditure (REE). RQ reflects the relative contribution of carbohydrate and fat oxidation and may therefore provide information about changes in substrate metabolism during the early phase of critical illness.\n\nRefeeding syndrome is characterized by metabolic and electrolyte disturbances following initiation or escalation of nutritional therapy after a period of insufficient intake. A decrease in serum phosphate is one of its characteristic biochemical features. However, currently used clinical risk-screening tools have limited ability to identify which critically ill patients will subsequently develop metabolic changes associated with refeeding. The present study investigates whether longitudinal changes in RQ may provide additional physiological information regarding the development of refeeding-related metabolic changes. The protocol specifically examines whether rising RQ values, including values ≥0.90, occur in association with or shortly after a clinically relevant fall in serum phosphate, and whether low RQ values may precede subsequent phosphate decreases.\n\nThis is a prospective observational study conducted in mechanically ventilated adult patients admitted to the central and neurointensive care units at Sahlgrenska University Hospital. Participants will undergo daily indirect calorimetry during the first five study days, with an additional measurement on day 7 when feasible. Measurements are planned at a standardized morning time point after a stabilization period without changes in ventilator settings, nutrition, vasoactive medication, or sedation. Only measurements fulfilling predefined steady-state and technical-quality criteria will be included in the main analyses.\n\nSerum phosphate, magnesium, potassium, and calcium will be recorded in temporal proximity to each indirect calorimetry measurement. Nutritional intake, including total energy and macronutrient delivery, as well as insulin treatment, PaCO2, temperature, ventilator parameters, and other relevant clinical variables will also be recorded. Risk of refeeding syndrome will be assessed using established NICE criteria at initiation of nutritional therapy.\n\nThe primary objective is to evaluate the within-participant association between serum phosphate and RQ over time. Longitudinal associations will be analyzed using mixed-effects regression models accounting for repeated measurements within participants. Time-lagged analyses will explore whether changes in RQ precede changes in serum phosphate or vice versa. Analyses will account for relevant potential confounders, including energy intake, carbohydrate intake, insulin treatment, PaCO2, and body temperature.\n\nSecondary objectives include evaluation of the relationship between other electrolyte changes and metabolic measurements, characterization of longitudinal changes in RQ and REE during the early ICU course, and assessment of the ability of NICE refeeding-risk criteria to identify patients who subsequently demonstrate metabolic and biochemical changes compatible with refeeding.\n\nThe study is observational. No study-specific changes are made to nutritional treatment, ventilator settings, or other clinical management. Indirect calorimetry, laboratory testing, and nutritional monitoring are performed within established clinical care, with research-specific activities consisting of standardized collection and analysis of these data.","Adult patients admitted to the central intensive care unit (CIVA) or neurointensive care unit (NIVA) at Sahlgrenska University Hospital who are receiving invasive mechanical ventilation, have an expected ICU stay of more than 72 hours, and have enteral or parenteral nutrition started or planned. Eligible patients are identified prospectively during routine daily ICU screening and included according to predefined inclusion and exclusion criteria.",[32],{"label":33,"type":25,"description":34,"interventionNames":35},"Prospective ICU Cohort","Mechanically ventilated adult intensive care patients followed prospectively during the first intensive care week with repeated indirect calorimetry, serum phosphate and other electrolyte measurements, and nutritional data collection. No study-specific change in nutrition, ventilator settings, or other clinical treatment is made.",[36],"Other: Nutritional Exposure During Early Critical Illness",[38],{"type":39,"name":40,"description":41,"armGroupLabels":42,"otherNames":25},"OTHER","Nutritional Exposure During Early Critical Illness","Enteral and\u002For parenteral nutrition is provided according to usual clinical care. Energy intake, carbohydrate intake, protein intake, fat intake, and changes in nutritional delivery are recorded prospectively to evaluate their relationship with respiratory quotient, serum phosphate, and other metabolic variables. No nutrition strategy is assigned by the study.",[33],[44],{"name":45,"role":46,"phone":47,"phoneExt":25,"email":48},"Carl Sjödin, PhD student","CONTACT","0707163277","carl.sjodin@vgregion.se",{"type":50,"investigatorFullName":51,"investigatorTitle":52,"investigatorAffiliation":5,"oldNameTitle":25,"oldOrganization":25},"PRINCIPAL_INVESTIGATOR","Carl Sjödin","Principal Investigator and Doctoral Student","100654441","respiratory-quotient-and-phosphate-changes-during-early-critical-illness-100654441",false,"NCT07800143","Respiratory Quotient and Phosphate Changes During Early Critical Illness","Association Between Serum Phosphate and Respiratory Quotient During Early Critical Illness: A Prospective Observational Study Using Indirect Calorimetry","IC-REFEED","Inclusion Criteria:\n\n* Age 18 years or older.\n* Admitted to the central intensive care unit (CIVA) or neurointensive care unit (NIVA) at Sahlgrenska University Hospital.\n* Receiving invasive mechanical ventilation.\n* Expected intensive care stay longer than 72 hours.\n* Enteral or parenteral nutritional therapy started or planned.\n* Arterial catheter in place for clinically indicated blood sampling.\n* Participation considered clinically safe by the responsible physician and research nurse.\n\nExclusion Criteria:\n\n* Ongoing or planned continuous renal replacement therapy or intermittent - hemodialysis (CRRT\u002FiHD).\n* Extracorporeal membrane oxygenation (ECMO).\n* Fraction of inspired oxygen (FiO2) \\>0.70.\n* Severe renal failure or rapidly increasing creatinine without dialysis, where phosphate levels may not adequately reflect metabolic changes.\n* Terminal illness or decision for end-of-life care.\n* Previous participation in the study during the same ICU admission.","ALL","18 Years",{"count":64,"type":65},40,"ESTIMATED","OBSERVATIONAL","Critically ill patients often experience major changes in metabolism during the first days of intensive care. When nutrition is started or increased after a period of reduced intake, some patients may develop refeeding syndrome, a potentially serious condition associated with shifts in electrolytes such as phosphate, potassium, and magnesium.\n\nThis study will investigate whether changes in respiratory quotient (RQ), measured by indirect calorimetry, are associated with changes in serum phosphate during the first intensive care week. RQ reflects the balance between oxygen consumption and carbon dioxide production and provides information about which energy substrates are being used by the body. A rising RQ may indicate increasing carbohydrate metabolism and could potentially provide an early physiological marker of metabolic changes associated with refeeding.\n\nMechanically ventilated adult intensive care patients will undergo daily indirect calorimetry during the first five days of the study period, with an additional measurement on day 7 when feasible. Serum phosphate and other electrolytes, nutritional intake, insulin treatment, ventilator parameters, and relevant physiological variables will be recorded at corresponding time points.\n\nThe study will also evaluate how well established screening criteria for refeeding risk, including the NICE criteria, identify patients who subsequently develop metabolic changes consistent with refeeding. No study-specific changes to nutrition or other treatment will be made.\n\nThis accurately reflects the observational nature of the study: routine IC, laboratory and nutritional data are collected without changing treatment.",[69,70,71],"Refeeding Syndrome","Critical Illness","Metabolic Changes During Critical Illness",[73,74,75,76,77,78,79,80,81,82],"Refeeding syndrome","respiratory quotient","serum phosphate","hypophosphatemia","indirect calorimetry","critical illness","nutrition","energy expenditure","NICE criteria","metabolic monitoring","NOT_YET_RECRUITING","2026-08-29",{"date":86,"type":87},"2026-09-02","ACTUAL",{"date":89,"type":65},"2026-11-01",{"date":91,"type":65},"2028-12-31",{"name":5,"class":6}]