SvO2 MONITORING

SvO₂ MONITORING – Client Preparation, Procedure, Interfering Factors, Complications and Steps to Prevent Complication

In venous oxygen saturation (SvO₂) monitoring, a fiberoptic flow-directed thermodilution pulmonary artery (PA) catheter measures SvO₂. It allows continuous monitoring of the body’s ability to deliver oxygen to tissues. SvO₂ measurements rapidly detect changes in hemodynamic stability. They are also used to evaluate a client’s response to drug administration, endotracheal tube suctioning, ventilator setting changes, and positive end expiratory pressure. This technique can reduce the need for frequent arterial blood gas levels, cardiac output, and other hemodynamic measurements

CLIENT PREPARATION

• Explain the procedure to the client and his family
• Make sure that they understand the procedure’s risk (related to catheter placement, pneumothorax, and infection) and expected outcomes
• Inform the client that the catheter placement procedure takes 15-30 minutes and that he must lie still during this time
• After catheter placement, his movements will be restricted
• Set-up and prime the equipment before catheter insertion, according to the manufacturer instructions and facility procedure and check catheter balloon patency and integrity
• Turn on the co-oximeter and pressure module for at least 10 minutes before insertion to allow them to warm-up. Set the alarm parameters 10% above and 10% below the client’s baseline SvO₂

PROCEDURE

• During catheter insertion, monitor the client’s vital signs and cardiac rhythm
• Assess the changes in ventilator status, possibly caused by the client’s dependent position and facial drapes
• Talk to him during procedure to provide reassurance and to assess for mental status changes
• Record pressure reading during insertion and any changes in the client’s condition
• The PA catheter can be connected to the optical module before or after insertion
• Record the initial SvO₂ recording and calibrate the o-oximeter to ensure accurate values
• To calibrate, draw a mixed venous blood sample for laboratory analysis; then compare the sample’s SvO₂ reading and attach selected strip to the chart as ordered
• The nurse should watch carefully for problems that can interfere with accurate testing, such as malfunctioning recording device, loose connections, balloon rupture, and clot formation at the catheter tip or in the fluid column

INTERFERING FACTORS

• Excessive catheter movement (catheter fling) caused by incorrect placement, leading to a dampened pressure tracing
• Catheter migration against a vessel wall, leading to constant occultation (permanent wedging) of the pulmonary artery
• Increased intrathoracic pressure, which raises catheter pressure, caused by mechanical ventilation with positive pressure

COMPLICATIONS

• Pneumothorax
• Pulmonary artery perfusion
• Air emboli
• Infection

STEPS TO PREVENT COMPLICATION

• Change the sterile dressing every 24 hours. If the dressing becomes soiled, change it more often
• Inspect the site for signs for infection with each dressing change
• Change the IV tubing every 24 hours
• Maintain a heparin flush system by verifying tight connections and gentle bubbling
• Closely monitor the client’s hemodynamic status
• Be gentle when wedging the catheter to prevent balloon rupture and pulmonary artery damages