Using Electrical Bioimpedance Assessments to Estimate Perioperative Total Body Water and Postoperative Fluid Need

Using Electrical Bioimpedance Assessments to Estimate Perioperative Total Body Water and Postoperative Fluid Need

The Use of Multifrequency Bioimpedance Assessments as an Estimate of Perioperative Total Body Volume and Postoperative Fluid Resuscitation

Being able to accurately monitor patient bodily fluid levels during and after surgery is very important, as there are a number of complications that can arise if a patient's fluid levels become unbalanced, such as swelling within or pressure on various bodily organ systems. There are several different ways that physicians can monitor a patient's fluid balance during and after surgery, such as measuring the amount of urine output or the use of central venous catheters which measure the pressure in the veins entering the heart. Most of these techniques are invasive since they require tubes to be inserted into the body. A potential alternative would be to use a noninvasive technique such as electrical bioimpedance (BIA). Bioimpedance assessments work by using small electrical currents that can accurately predict both the water surrounding the outside of cells in the body, as well as the total amount of water in the entire body. Electrical bioimpedance assessments have been used to estimate patient swelling following surgery (edema), to measure the volume of blood the heart is pumping out, as well as to calculate body fat percentages. The goal of this study is to relate this technology to fluid shifts within the body that occur as a result of surgery, in particular, major intra-abdominal surgeries. By using bioimpedance during and after surgery, the investigators will compare the data collected with that calculated by using traditional measures of body fluid status, such as urine output and intraoperative blood loss. During the study, the bioimpedance monitors will not replace the standard bodily fluid monitors and will not interfere with their readings. Additionally, the electrical current produced by the bioimpedance monitors is too small for patients to feel and will not interfere with medical devices such as pacemakers.

Being able to accurately monitor patient bodily fluid levels during and after surgery is very important, as there are a number of complications that can arise if a patient's fluid levels become unbalanced, such as swelling within or pressure on various bodily organ systems. There are several different ways that physicians can monitor a patient's fluid balance during and after surgery, such as measuring the amount of urine output or the use of central venous catheters which measure the pressure in the veins entering the heart. Most of these techniques are invasive since they require tubes to be inserted into the body. A potential alternative would be to use a noninvasive technique such as electrical bioimpedance (BIA). Bioimpedance assessments work by using small electrical currents that can accurately predict both the water surrounding the outside of cells in the body, as well as the total amount of water in the entire body. Electrical bioimpedance assessments have been used to estimate patient swelling following surgery (edema), to measure the volume of blood the heart is pumping out, as well as to calculate body fat percentages. The goal of this study is to relate this technology to fluid shifts within the body that occur as a result of surgery, in particular, major intra-abdominal surgeries. By using bioimpedance during and after surgery, the investigators will compare the data collected with that calculated by using traditional measures of body fluid status, such as urine output and intraoperative blood loss. During the study, the bioimpedance monitors will not replace the standard bodily fluid monitors and will not interfere with their readings. Additionally, the electrical current produced by the bioimpedance monitors is too small for patients to feel and will not interfere with medical devices such as pacemakers.

Electrical Bioimpedance, Major Intra-abdominal Surgical Procedures, Total Body Volume, Fluid Resuscitation

The only group will be those patients having major intra-abdominal surgical procedures. Each patient involved in the study will be evaluated with a bioimpedance monitor ('Bodystat Quadscan 4000') to assess total body water, estimated body water, and intravascular body water volume preoperatively, postoperatively, and daily during the postoperative recovery period. Bioimpedance Assessment

Each patient involved in the study will be evaluated with a bioimpedance monitor to assess total body water, estimated body water, and intravascular body water volume preoperatively, postoperatively, and daily during the postoperative recovery period. Bioimpedance Assessment

Bioimpedance assessment measurements were recorded for each participant before the surgical procedure

Bioimpedance assessment measurements were recorded for each participant six hours following the surgical procedure

Postoperative bioimpedance assessment measurements were recorded for each participant. One average across this time frame was recorded.

Intracellular water volume was recorded for each participant 6 hours following the surgical procedure.

Extracellular water volume was recorded for each participant 6 hours following the surgical procedure.

Each participant had a daily calculated fluid balance taken during the course of an approximate 8 day period

A classification scale to assess the fitness of patients before surgery The ASA score is a subjective assessment of a patient's overall physical health. The scale ranges from 1 to 5. ASA 1 A normal healthy patient. ASA 2 A patient with mild systemic disease. ASA 3 A patient with severe systemic disease. ASA 4 A patient with severe systemic disease that is a constant threat to life. ASA 5 A moribund patient who is not expected to survive

Inclusion Criteria: Patients having major intra-abdominal procedures under general anesthesia requiring hospitalization postoperatively during the initial recovery from surgery. Exclusion Criteria: Patients not having intra-abdominal procedures (ie. Thyroidectomy, open or laparoscopic inguinal hernia repair, excision of skin lesions, breast procedures) Patients having outpatient surgery Patients having laparoscopic cholecystectomies, laparoscopic or open appendectomies Patients having bariatric surgery (because the bioimpedance assessment technology has proven to be unreliable in obese populations) Morbidly obese patients (BMI >40) Unable to provide informed consent Pregnant women