Neuroanesthesiology Management of Blood Pressure in Beach Chair Position Surgery
An Early Case Series
An early case series described four cases of ischemic brain and spinal cord injury that were attributed to the beach chair position. In this position, a 12-inch vertical gradient is assumed between the midpoint of a blood pressure cuff and the heart. This gradient can lead to hydrostatic hypotension, which can in turn cause ischemic injury to the brain and spinal cord. To prevent this complication, it is important to maintain adequate blood pressure and to allow for hydrostatic gradient.
Monitoring Standards
There is no widely agreed-upon monitoring standard for patients in the beach chair position. However, it is generally agreed that blood pressure should be monitored frequently, and that the patient should be observed for signs of distress. Some anesthesiologists also recommend monitoring the patient's oxygen saturation and end-tidal carbon dioxide levels.
Increasing FiO2
Increasing the FiO2 (fraction of inspired oxygen) can help to prevent hypoxemia, which can lead to ischemic injury to the brain and spinal cord. It is important to titrate the FiO2 carefully to avoid hyperoxia, which can also be harmful. A FiO2 of 0.5 to 0.6 is generally considered to be safe and effective.
Waterfall Concept
Neuroanesthesiologists manage blood pressure according to the waterfall concept when performing sitting position surgery. This concept involves maintaining a high mean arterial pressure (MAP) during induction and intubation, followed by a gradual decrease in MAP during the surgery. The goal of this approach is to prevent hypotension and its associated risks, while also avoiding hypertension and its potential complications. The MAP is typically maintained at around 80 to 90 mmHg during the surgery.
Patient Positioning
After induction of anesthesia, the patient is placed in the beach chair position. The head and neck are supported with pillows, and the legs are elevated. The patient's arms are placed at their sides or on arm boards. The patient's position should be checked frequently to ensure that they are comfortable and that there is no pressure on the nerves or blood vessels.
Blood Pressure Monitoring
Blood pressure is measured with a noninvasive cuff on the patient's upper arm. The cuff should be placed at the level of the heart. The blood pressure should be measured frequently, and the patient should be observed for signs of distress. Some anesthesiologists also recommend monitoring the patient's oxygen saturation and end-tidal carbon dioxide levels.
Ventilation Strategies
The influence of ventilation strategies on blood pressure in the beach chair position is not well understood. Some studies have suggested that positive end-expiratory pressure (PEEP) may help to maintain blood pressure, while other studies have found no effect. The optimal ventilation strategy for patients in the beach chair position is likely to vary depending on the individual patient's circumstances.
Conclusion
The beach chair position is a common position for sitting position surgery. It is important to be aware of the potential risks of this position, including the risk of ischemic brain and spinal cord injury. By following the guidelines outlined in this article, you can help to prevent these complications and ensure the safety of your patients.
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