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Some studies indicate that approximately 16% of patients that undergo surgery develop a peripheral nerve injury due to poor positioning. Luckily, these injuries are temporary and resolve within week or months, however, they are still avoidable. In following our nursing standards and the ethical principle of non-maleficence we should ensure that our vulnerable patients are positioned appropriately.
Appropriate patient positioning allows for good surgical access, whilst allowing the anaesthetist to access the airway, intravenous and monitoring devices. Patient positioning should not compromise the patients cardiovascular, and respiratory function, nor cause damage to the nervous, muscular and integumentary systems.
Patients surgical outcomes depend on good positioning.
Cardiovascular Concerns -
Patients undergoing anaesthesia and surgery have complex venous, arterial and cardiac concerns which can be exacerbated by positioning. For instance a patient in the supine position or the lithotomy position will have increased venous return and therefore increase cardiac pre-load. Or, patients who are in reverse trendelenberg or beach chair position can suffer ischemic strokes due to poor cerebral perfusion.
So remember to always look at your patient, and think about how their position can effect their cardiovascular system.
Respiratory Concerns -
Typically, patients under anaesthesia have a reduced tidal volume and functional residual capacity. Positive pressure ventilation and muscle relaxation may ameliorate ventilation-perfusion (VQ) mismatches under general anaesthesia by maintaining adequate minute ventilation and reducing atelectasis. However, patient positioning has a great impact on VQ mismatching, and on diaphragm pressure. Take for instance laparoscopic surgery, the pressure from the pneumoperitoneum can misplace the diaphragm, making ventilation more difficult.
Other Injuries -
Other common injuries include pressure areas from excessive pressure or friction. Nerve injuries are common, and often caused by poor patient positioning. The most commonly injured nerves are the ulnar nerve (from poor arm positioning), brachial nerve (also from poor arm positioning), spinal cord (due to many reasons), and sciatic nerve (from poor positioning during lithotomy).
As a nurse it is an important responsibility to ensure my patients are positioned well for their surgery, to avoid any undue harm.
A little tip - When positioning the arms on arm-boards, use gel pads where possible, and ensure that they are not abducted at angles greater than 90 degrees. Also ensure that they are slightly supinated to prevent ulnar and brachial nerve injuries.
If the arms are adducted (placed beside the body), make sure that the palms are facing the hips to prevent ulnar nerve damage.
AKA Dorsal Decubitus.
One of the most common positions for patients to be in during surgery, this position has many variants which will be discussed further on. In this position patients are laying flat on their back, arm may be beside their body or extended on an arm board. The head is usually supported with a cushion.
In this position the entire body is at the same level of the heart, therefore hemodynamic reserve is best maintained. The biggest concern in this position is pressure injuries from prolonged pressure on bony prominences from the hard theatre table - usually the heels, sacrum, elbow, scapula and occiput.
Remember to think of any cardiovascular and respiratory concerns that this position could have.
There are three variations of this position:
Lithotomy is commonly used for gynaecology, rectal or urological procedures, or other procedures that involve the pelvic floor. It involves the the patient to be positioned supine, to start. Once they are inducted and asleep, the legs are placed in either stirrups or 'candy canes' to allow for access. The end of the table is then removed.
Placing a patient into lithotomy position requires care, attention and team work as there are many risks involved. The patients hands and fingers may become pinched in the bed, or in the leg supports. Patients need to be placed appropriately on the end of the table, too much over the edge and we are causing back strain and back injury. If they are too far from the edge we are impeding surgical access.
Additional care must be taken to ensure that the legs are lifted up equally, as this prevents peroneal nerve injuries.
A rare, however devastating consequence of this position is lower extremity compartment syndrome. This occurs in long procedures where the lithotomy position is combined with the trendelenburg position, causing poor perfusion to the lower limbs leading to necrosis.
Lateral Decubitus -
The position is most commonly used for surgeries involving the thorax, retroperitoneal structures or the hip. In this position the patient rests on their non-operative side, whilst their operative side is facing up (simply, they are laying on their side). The patients are supported with anterior and posterior supports. The non-dependant leg is usually place either in front of the depend leg (like in the sims position), or a pillow is placed between the legs (to prevent pressure areas). The arms are usually positioned in front of the patient. The dependant arm rests upon a padded arm-board and the non-dependent arm is usually place over a folded pillow or in an arm cradle.
The biggest concern in this position is brachial plexus injury, for this reason an auxiliary roll is used.
What about respiratory concerns? This position compromises pulmonary function by causing a lateral weight on the mediastinum and a disproportionate cephalad pressure of abdominal contents on the dependant diaphragm decreased compliance and favours non-dependant lung ventilation. This is a great example of a VQ mismatch!
This position is often one of the most difficult to get patients into. It is fraught with risks and extreme care and team work must be taken. In this position the patient is laying on their stomach, giving surgical access to the posterior skull, spine, buttocks and perirectal area.
Pressure areas are common in this position - areas such as the knees, feet, pelvis and shoulders are at risk. Significant musculoskeletal injury can occur is care is not taken when positioning the arms.
Furthermore pressure on the face and eyes can cause significant damage, therefore specialised head rests are used. Remember that access to the airway is difficult in this position, so patients are commonly intubated with an endotracheal tube.
Sitting (Fowlers Position) -
In this position the patients are sitting, giving excellent surgical access to the shoulders and skull. The main concern with this position is the head and neck position, as they often cannot be changed once surgery has commenced (as the patient is draped). Furthermore, cerebral perfusion can be compromised if the patients blood pressure drops too low, this overlook has already caused a few deaths. Therefore specific cerebral perfusion monitors can be used, and are the gold standard.
This position is infrequently used, so we wont talk too much about it.