Otterbein/Grant CRNA Patient Positioning Review

Also need to protect the dependent eye in the lateral position.

Operative positioning aims to achieve several goals, including optimum surgical exposure, access for monitoring, preventing complications and injuries, and maintaining body integrity and physiological functions. These goals ensure that the surgical procedure can be performed effectively and safely. Optimum surgical exposure allows the surgeon to have a clear view of the surgical site, facilitating accurate and precise interventions. Access for monitoring ensures that vital signs and other parameters can be continuously monitored during the procedure. Preventing complications and injuries involves positioning the patient in a way that minimizes the risk of nerve damage, pressure ulcers, and other adverse events. Lastly, maintaining body integrity and physiological functions involves positioning the patient in a manner that does not compromise blood flow, respiration, or other bodily functions.

The treatment of a venous air embolism involves removing the air from the affected area. This is done by using a multiorifice central venous catheter to aspirate or suction out the air. This method helps to prevent further complications and restore proper blood flow. Therefore, the statement is true.

Diaphragmatic excursion decreases with the shifting of abdominal contents.

In extreme lithotomy positioning, compliance and tidal volumes decrease because the position restricts the movement of the diaphragm and chest wall, leading to decreased lung expansion. However, airway pressures increase because the restricted movement of the chest and abdomen increases the resistance to airflow, causing an increase in pressure needed to maintain adequate ventilation.

Decreases.

Venous return decreases d/t abolition of normal muscle tone.

When the patient is moved from a supine position to a seated position, their blood pressure is expected to decrease. This is because the change in position causes a redistribution of blood in the body. When the patient is supine, blood is evenly distributed throughout the body, but when they are seated, blood tends to pool in the lower extremities due to gravity. This pooling leads to a decrease in venous return to the heart, resulting in a decrease in cardiac output and subsequently a decrease in blood pressure.

In the lateral position, the dependent lung (lower lung) is compressed due to the weight of the body, causing closing volumes to occur above the functional residual capacity (FRC). Closing volumes refer to the lung volume at which small airways begin to close during expiration. This means that the dependent lung is more prone to collapse or atelectasis, which is the partial or complete collapse of a lung or a section of it. Therefore, patients in the lateral position are susceptible to atelectasis.

Due to displacement of the diaphragm by abdominal contents as well as the downward force of the mediastinum.

Elderly pts with comorbidities are less adaptive.

Compensatory mechanisms to increase HR when hypotension occurs are blunted by GA, rendering CO and BP more susceptible to gravitational (positioning) forces

In the lithotomy and Trendelenburg positions, hypovolemia can be unrecognized because the mean arterial pressure (MAP) can appear normal despite a volume deficit due to a large amount of venous return. Similarly, hypotension can also be unrecognized for the same reason. Both conditions can go unnoticed because the blood pressure may not show significant changes despite the underlying volume deficit or low blood pressure.

Sitting position puts the patient at greater risk for venous air embolism. In this position, there is a higher chance of air entering the venous system through the central venous catheter or during surgical procedures. The sitting position allows air to accumulate in the right atrium, increasing the risk of air embolism.

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Due to blood pooling in the dependent areas of the body

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In the prone position, the improvement in oxygenation is caused by better matching of ventilation and perfusion. This means that the air being breathed in reaches the areas of the lungs that have good blood flow, allowing for more efficient gas exchange. This position helps to optimize the distribution of air and blood within the lungs, leading to improved oxygenation. Changes in lung volumes/capacities may also have an impact on oxygenation, but the primary factor in the prone position is the improved matching of ventilation and perfusion.

The correct answer is "Sitting." When a patient is sitting, the West zones of the lung are normal in the operating room. This is because in the sitting position, gravity helps to distribute the air and blood flow more evenly throughout the lungs. In other positions such as supine, prone, or side-lying, the distribution of air and blood flow may be affected, leading to abnormal lung zones.

In normal lithotomy position w/o Trendelenberg, FRC decrease is similar to the supine position. BUT with extreme flexion of the thighs in the exaggerated litho position compresses the abdomen, shifts the abd. viscera cephalad, and limits diaphragmatic movement.

The sitting position has less effect on V/Q redistribution and on lung volumes and it also it allows the greatest expansion of the dependent regions of the lungs.

In the prone position, the abdomen is allowed to hang freely, which reduces the pressure on the diaphragm and allows it to move more easily. This increased mobility of the diaphragm allows for a greater expansion of the lungs during inhalation, leading to an increase in functional residual capacity (FRC). FRC is the volume of air that remains in the lungs after a normal exhalation, and it represents the amount of air available for gas exchange. Therefore, in the prone position, FRC increases.

Patients in the lateral position may experience some decrease in oxygenation and many will attempt to correct this by using TV, increasing the risk for barotrauma and further O2 loss.

When the patient is in the sitting position with flexed lower extremities, the abdominal contents shift upwards against the diaphragm. This causes a decrease in functional residual capacity (FRC), which is the volume of air remaining in the lungs after a normal exhalation. In the supine position, the abdominal contents also shift upwards due to gravity, leading to a similar decrease in FRC. Therefore, the change in FRC seen in the sitting position with flexed lower extremities is similar to the change seen in the supine position.

The mediastinum shifting cephalad occurs with Trendelenberg positioning.

Tourniquet pressure that exceeds 400 mmHg or is applied for longer than 2 hours can increase the risk of peripheral nerve injury. This means that if the pressure applied by the tourniquet is too high or if it is left on for too long, it can potentially damage the nerves in the affected area. Therefore, it is important to monitor and control the pressure and duration of tourniquet use to minimize the risk of nerve injury.

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