Problems and Complications

Risk factors for overall postoperative complications

Risk factors for postoperative infection

– Age between 30 and 60 years

– Diabetes

– Chronic obstructive pulmonary disease

– Coronary heart disease

– Arterial hypertension

– History of cerebrovascular accident

– Disseminated cancer

– ASA class III or higher

– Inpatient shoulder arthroscopy

– Duration of surgery >90 min

– Further surgical procedures in addition to shoulder arthroscopy

– Revision surgery

– Male sex

– Age <65 years

– Obesity

– Alcohol use

– Chronic anemia

– Inflammatory arthritis

– Malnutrition

– Infection

– Liver disease

– Chronic kidney disease

– Intraoperative steroid injection

Patient history aids the identification of risk factors of general problems and complications. The most relevant risk factors for per operative complications are cardiovascular diseases like high arterial blood pressure and coronary heart disease, obstructive pulmonary diseases, bleeding disorder and cerebral hypoperfusion. These risk factors need to be investigated prior to surgery by the anesthesiologist as well as the shoulder surgeon. Because shoulder arthroscopy is a planned surgical procedure in most of the cases, patients with one ore more of these major risk factors need to be investigated and treated by particular subspecialists (e. g. cardiologist, neurologist, internist). If the risk for anesthesia and the surgical procedure achieves an unacceptable extent, shoulder arthroscopy should not be carried out.

The preoperative investigation of risk factors may influence patient positioning and pre- and postoperative medication as well as the type of anesthesia. The beach chair position yields a risk for cerebral desaturation [3]. This is why patients suffering from cardiovascular diseases and cerebral hypoperfusion are endangered during shoulder arthroscopy carried out in this particular position. During general anesthesia the blood pressure decreases and the blood vessels are dilated. This dilation of peripheral vessels leads to a changed distribution of blood volume and a consecutively reduced cardiac pre- and afterload. These changes may potentially result in cerebral or cardiac hypoperfusion due to a reduced mean arterial blood pressure in the beach chair position. While a certain amount hypoperfusion is usually tolerated in young and healthy patients, older patients with cardiovascular diseases have the risk to sustain stroke or acute coronary syndrome.

For patients with a high risk for cerebral hypoperfusion or stroke the surgeon should consider performing shoulder arthroscopy in the lateral decubitus rather than the beach chair position. A true beach chair position with an elevation of the upper body of 30° is another feasible patient position in these cases. This position is also recommendable for patients with cardiovascular diseases and obstructive pulmonary diseases.

Events of cerebral hypoperfusion are frequent (40%) in arthroscopic shoulder surgery [4]. A non-invasive monitoring of cerebral oxygen saturation is generally recommendable to avoid cerebral hypoperfusion. For the measurement the oxygen concentration is continuously tested with electrodes on the forehead by near infrared spectroscopy. The oxygen concentration of the skin allows for estimating cerebral oxygenation. In patients with high risk for stroke such a system should be employed during general anesthesia. Several manufacturers provide these systems (e.g. INVOS by Medtronic, FORE-SIGHT by Casmed).

If general anesthesia yields a high risk for intraoperative complications like stroke or cardiac failure, regional anesthesia with a nerve block should be considered. This requires optimal local anesthesia of the supraclavicular brachial plexus by an experienced anesthesiologist and mild sedation of the patient.

Bleeding disorders like hemophilia or platelet dysfunction often need to start the specific bleeding prophylaxis prior to the surgical procedure. For these patients a substitution plan should be provided by and internist. A radiofrequency device (e.g. VAPR by DePuy Mitek) should be used during shoulder arthroscopy for optimal coagulation of any bleeding vessels to avoid intra- and postoperative surgical complications.

1.2 Per Operative Complications

Per operative complications may occur due to problems during anesthesia, patient positioning and the surgical procedure itself (Table 1.2).

Table 1.2

Important intraoperative general problems and complications in arthroscopic shoulder surgery concerning anesthesia, surgical visualization and patient positioning

Anesthesia	Visualization	Patient positioning
– Nerve block complications (pneumothorax, nerve lesions) – High blood pressure (bleeding) – Low blood pressure (cerebral hypoperfusion)	– Vessel injury – Loss of arthroscopic fluid (bleeding) – Low pump pressure (bleeding)	– Nerve traction injury – Stress ulcers – Cerebral hypoperfusion (beach chair) – Deviation of head and neck

Anesthesia

Visualization

Patient positioning

– Nerve block complications (pneumothorax, nerve lesions)

– High blood pressure (bleeding)

– Low blood pressure (cerebral hypoperfusion)

– Vessel injury

– Loss of arthroscopic fluid (bleeding)

– Low pump pressure (bleeding)

– Nerve traction injury

– Stress ulcers

– Cerebral hypoperfusion (beach chair)

– Deviation of head and neck

1.2.1 Anesthesia

Per operative complications may already arise before the shoulder surgeon has started the procedure. This chapter does not deal with the risks of general anesthesia but rather with the risks of an additional nerve block and of the intraoperative decrease of blood pressure.

A nerve block is usually performed as an interscalene block of the brachial plexus. If more complex arthroscopic procedures like repair of a massive rotator cuff tear, coracoid transfer or release of the suprascapular nerve are planned preoperatively, an interscalene nerve block is mandatory to avoid uncontrolled increase of blood pressure caused by increasing pain. Positioned correctly, it provides several benefits improving the surgical procedure and postoperative pain management. It is, however, a risky procedure, because of potential nerve injury, hematoma, pneumothorax or infection [5, 6].

Ultrasound guidance should be employed to avoid incorrect positioning or injury during the nerve block [7]. If the block is only conducted with electrostimulation, there is a higher risk for a wrong position or injury of the surrounding anatomical structures [8].

If the nerve block is positioned correctly it helps to avoid increasing blood pressure and consecutive bleeding next to a reduced need for narcotics.

Blood pressure is always a point of discussion between shoulder surgeons and anesthesiologists. While shoulder surgeons want to keep it as low as possible to avoid bleeding and the need for high pump pressure, it must not fall below a certain level (mean arterial blood pressure above 60–65 mmHg) to avoid organ hypoperfusion. However, the critical blood pressure differs from patient to patient. While young and healthy individuals may tolerate a mean arterial blood pressure below 60 mmHg, older patients with general diseases may not even tolerate short periods of a mean arterial blood pressure below 70 mmHg.

A critically low blood pressure may cause stroke or even death. This is because non-invasive continuous monitoring of cerebral oxygen saturation should be employed generally. A life threatening decrease of blood pressure may also be detected using invasive blood pressure measurement using a system introduced in the radial artery. The necessity of such a device needs to be discussed with the anesthesiologist prior to surgery.

1.2.2 Patient Positioning

Patient positioning should be carried out or supervised by an experienced shoulder surgeon. In the majority of the cases incorrect patient positioning only leads to poor access of the anatomical region or poor visualization. But it may also provoke irreversible injuries caused by traction of the brachial plexus. Inadequate cushioning of sensitive regions like heels or the elbow may cause stress ulcers. A longer duration of surgery leads to a higher risk for these injuries.

Since beach chair position may lead to significant decrease of arterial blood pressure, patient positioning needs to be performed slowly under supervision of the anesthesiologist. In endangered patients the blood pressure needs to be measured frequently, while the patient is gradually brought into a sitting position. If the pressure decreases significantly, the sitting position should be converted to a more lying position, while the anesthesiologist needs to counteract by adjusting the narcotics and the use of sympathomimetic drugs. The final angle of the upright patient position should be kept as small as possible, since a more upright position is related to lower cerebral oxygen saturation [9].

Once the patient’s trunk is in an upright position he needs to be secured with belts or supporting braces to prevent intraoperative migration or even falling of the patient (Fig. 1.1). The head and the neck need special care. Next to security of the endotracheal tube the head is to be fixed in a neutral rotation, side deviation and inclination to avoid traction injuries of the brachial plexus and to avoid reduced blood flow of the carotid or vertebral artery. Furthermore eyes and ears require special regard to protect them from stress ulcers.

../images/437034_1_En_1_Chapter/437034_1_En_1_Fig1_HTML.png — Fig. 1.1

Shoulder arthroscopy in the beach chair position is related to an increased risk for cerebral desaturation caused by low blood pressure as well as traction injuries of the brachial plexus and intraoperative migration of the patient. A belt is used to prevent the patient’s buttock to move anteriorly. Knees and heels need careful bolstering. The patient’s head is positioned without any tension of the neck without any deviation in the sagittal or in the frontal plane

Especially for procedures requiring medial portals (e.g. suprascapular nerve release or stabilization of the acromioclavicular joint) a slight deviation of the head to the contralateral side is sometimes mandatory, to gain undisturbed access to these portals. This deviation must not create any tension to the brachial plexus, while the access to the portals needs to be guaranteed. In small patients it is sometimes necessary to obtain the deviation to the contralateral side only for a short period, because the tension of the neck and the brachial plexus would otherwise be unacceptable.

Increased tension to the neck or the arm with an increased risk for traction injuries of neurovascular structures may also be induced, if the patient’s hip is shifted to the contralateral side, thus provoking bending of the trunk and consecutive traction to head and neck. If an arm holder is employed, care must be taken to avoid over tensioning of the arm. Intraoperatively the position of the head should be controlled frequently to prevent traction injuries.

Although the lateral decubitus position is less risky in terms of low blood pressure injuries caused by traction or pressure are possible as well [10]. The patient’s body needs to be protected against intraoperative migration using a vacuum mattress or supporting braces. The contralateral arm needs to be pulled anteriorly to prevent pressure injuries of the axillary neurovascular structures. Legs, knees and feet require careful cushioning to avoid stress ulcers.

A shoulder suspension system provides continuous axial tension with or without additional lateral traction (Fig. 1.2). Tension may be increased mechanically during the surgical procedure. Care must be taken to keep the tension as low and as short as possible. Otherwise the risk for traction of the brachial plexus increases, especially if the head is not positioned neutrally but deviated to the contralateral side.