Effect of Crystalloids With Different SID on pH, and Urinary Electrolytes During General Anesthesia

Study Overview
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Brief Summary
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The present study will investigate variations in acid base equilibrium caused by the administration of four different crystalloids with increasing strong ion difference (0.9% saline, Ringer's lactate, Ringer's acetate, plasmalyte-like solution) in patients during general anesthesia. The same crystalloid will be administered throughout the surgery. In order to assess the effect of hemodilution, every patient will receive two fluid boli with different volumes of the same solution. pH and strong ion variations, togher with the renal response to acid base disturbances, will be analysed.

Official Title
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Effect of Crystalloids With Different SID on Hemodilution, Plasmatic Acid Base Equilibrium and Urinary Electrolytes in Patients During General Anesthesia

Conditions
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SID, Acid-Base Imbalance

Intervention / Treatment
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* Other: 0.9% saline administration
* Other: Ringer's lactate administration
* Other: Plasmalyte-like solution administration


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients (between 18 and 75 years old); ASA (American Society of Anesthesiologists) physical status classification system 1 or 2; Patients undergoing spinal surgery under general anesthesia, intubated and mechanically ventilated; Normal preoperative albumin; Surgery with an estimated duration of at least 3 hours. Exclusion Criteria: Patients who are pregnant; Patients with obesity (BMI > 35); Patients with a chronic obstructive pulmonary disease (COPD); Patients with obstructive sleep apnea (OSA) treated with CPAP; Patients with chronic heart failure (CHF) with a NYHA (New York Heart Association) class ≥2; Patients receiving diuretics in the pre-operative period; Patients with a chronic kidney disease (CKD), defined as a GFR < 60 ml/min/1.73 m2; Patients with diabetes mellitus treated with insulin; Patients with myopathies; Patients undergoing a surgery with likely fluid losses or with unexpected bleeding during surgery.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Chloride-rich solution<br>Patients will receive two boluses of 10 and 20 ml/kg of the 0.9% saline in two different moments after at least 1 hour from each other. Plasma arterial blood gas (ABG) and electrolytes, along with plasmatic creatinine, albumin and phosphate will be measured immediately before and five minutes after fluid boluses. Urinary electrolytes (Na, K, Cl) will be measured immediately before fluid bolus and after one hour from fluid administration along with ABG and plasmatic electrolytes and creatinine, phosphate and albumin. | Other: 0.9% saline administration<br>* Each patient will receive 0.9%saline based on attending physician decision<br>|
| Experimental: Low-chloride solution A<br>Patients will receive two boluses of 10 and 20 ml/kg of Ringer's lactate in two different moments after at least 1 hour from each other. Plasma arterial blood gas (ABG) and electrolytes, along with plasmatic creatinine, albumin and phosphate will be measured immediately before and five minutes after fluid boluses. Urinary electrolytes (Na, K, Cl) will be measured immediately before fluid bolus and after one hour from fluid administration along with ABG and plasmatic electrolytes and creatinine, phosphate and albumin. | Other: Ringer's lactate administration<br>* Each patient will receive Ringer's lactate based on attending physician decision<br>|
| Experimental: Very low-chloride solution<br>Patients will receive two boluses of 10 and 20 ml/kg of a plasmalyte-like solution (namely soluzione elettrolitica reintegrante [SER]) in two different moments after at least 1 hour from each other. Plasma arterial blood gas (ABG) and electrolytes, along with plasmatic creatinine, albumin and phosphate will be measured immediately before and five minutes after fluid boluses. Urinary electrolytes (Na, K, Cl) will be measured immediately before fluid bolus and after one hour from fluid administration along with ABG and plasmatic electrolytes and creatinine, phosphate and albumin. | Other: Plasmalyte-like solution administration<br>* Each patient will receive Plasmalyte-like solution based on attending physician decision<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| pH modification | The primary outcome of this physiological study is to evaluate, in vivo, the effect of crystalloid administration with different SID on acid base equilibrium, in particular pH variations will be considered. | Surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Urinary SID modification (mEq/L) after crystalloids administration with different SID and chloride load | renal response to acid base disturbances caused by different crystalloid infusions and different volumes. | Surgery | 
| SID and plasmatic weak acid (A tot) variations measured in mEq/L | We will explore the changes in apparent SID (SIDapp) and effective SID (SIDeff) and strong ion gap (SIG), as well as A tot after administration of solutions with different SID | Surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pH, crystalloids