**3. Preoperative study**

Anesthesia visit should be used to carry out both a global study of the surgical-anesthetic risk, and to reduce the patient's anxiety before surgery. Indeed, the treatment of postoperative pain begins in this pre-operative period, with apprehension and anxiety increasing when patients are poorly informed as to the upcoming procedures. In examining the personal background of the patient, it is important to note any previous surgical interventions, particularly those in the cervical and thoracic region.

upper airway should be explored in detail, from the mouth to the base of the neck, noting and missing teeth or dentures that might make ventilation and endotracheal intubation more difficult. Observe whether the patient has a short neck or an increased cervical diameter, which determines the location of skin reference points for locking and positioning if an

Anesthesia for Arthroscopic Shoulder Surgery 53

position of the patient during arthroscopic examination is fundamental and poor positioning will affect the surgeon's movements, dexterity and maneuverability of the instruments, and traction vector placement. The position of the patient will depend on the type of surgery, the personal preferences of the surgeon and the specific workplace in question. Correct initial placement of the patient avoids subsequent postural adjustments

Proposed This method was first proposed by Wiley and Older (12), whereby the patient is positioned with a lateral tilt, leaving the arm exposed. No traction should be used, and the position of flexion and adduction of the arm should allow easy penetration of the shoulder

In order to obtain greater diastasis of the joint, Andrews and Carson (13) positioned the arm at about 70º of abduction and 15º of flexion, with adequate longitudinal tension, although this may lead to overstretching the neurovascular structures (Figure 1). Different drivelines can be applied to the upper limb but the weight applied to traction should under no circumstances exceed 4-6 kg. Moreover, as the drive can induce ischemic stroke, traction for more than 2 hours should be avoided. Paulos (14) reported 30% transitional neuroapraxia after shoulder arthroscopy. Before traction, the upper limb should be slightly rotated internally at the elbow to reduce the tension on glenohumeral ligaments, thereby augmenting the joint space. In preparing the operating room is important to place the anesthesia machine beside the surgical bed to provide the surgeon with sufficient room to

during surgery, which can increase both surgical and recovery times.

**5. Lateral decubitus** 

move and operate (Table 1).

Fig. 1. Lateral decubitus position.

joint.

ultrasound transducer is employed. It may be difficult to maintain good ventilation in obese patients and to use the neurostimulator to find the brachial plexus in the different supraclavicular approaches. The preanesthesia visit is a good time to perform this exploration. Chronic lung disease may be a relative contraindication to performing a bilateral interscalene block, since phrenic nerve block exacerbates the poor respiratory function in such patients. In such cases additional studies may be necessary, such as chest RX and basic tests of respiratory function (*e.g.,* spirometry).

We explore the contralateral arm to see determine whether the patient has a clear vein network channel for peripheral venous administration, or whether an alternative route of administration will be required. While the patient must fully informed of the technique they are to undergo, if told "a needle will be inserted into your neck" their levels anxiety are likely to rise. However, a correct explanation of the technique, starting at the pre-operative visit and continuing up to and during the procedure, along with adequate sedation, will significantly increase the patient´s satisfaction with the technique, as well as their confidence in the anesthesiologist.

A blood analysis including blood counts and basic clotting biochemistry must be performed, particularly for more invasive surgical procedures such as prosthetic glenohumeral joint or proximal humerus fractures. Arthroscopic procedures themselves do not involve bleeding. A severe impairment of clotting is an absolute contraindication for performing the regional block technique, although it can be partially permissive if taking into account the benefit/risk in those patient at the limits of normality, and particularly when ultrasoundguided block is performed by an expert. We also investigate factors or conditions that potentially increase the risk of post-operative nausea and vomiting in the patient, which may require prophylactic drugs or adaptation of the anesthetic technique.

the patient must be informed of the pain they may experience after the surgical procedure, as well as of the various analgesic strategies available. of and understand the information provided during the pre-anesthesia visit, including the possible associated complications and setbacks, and they must provide informed consent for the anesthetic techniques that may be employed.

#### **4. General considerations during surgery**

Whether in the operating theatre or in an alternative location approved to perform the peripheral nerve block, access is required to a peripheral vein in the arm contralateral to the surgery at least. Where premedication with benzodiazepines or other hypnotics is required, it is desirable to provide the patient with a supplementary source of oxygen in the form of a low flow nasal cannula or face mask (11). Shoulder As shoulder arthroscopy does not involve a large degree of fluid loss, a small venous line will suffice (a 20G needle should be adequate). However, fluid deficits due to pre-operative fasting should be calculated.

Basic patient monitoring principles should be applied, including circulatory parameters such as heart rate and non-invasive blood pressure, partial oxygen saturation, continuous electrocardiogram leads II (for better evaluation of rhythm disturbances) and V5 (for better assessment of ST segment changes and repolarization). In cases where the patient receives mechanical ventilation or spontaneous ventilation through a supraglottic airway device, FiO2 and fractional exhaled CO2 should be continuously monitored, along with basic ventilation parameters (tidal volume, respiratory rate, index I:E, airway pressure and PEEP if applicable). The patient´s temperature should also be controlled systematically, given the considerable loss of heat that can occur during surgery.

position of the patient during arthroscopic examination is fundamental and poor positioning will affect the surgeon's movements, dexterity and maneuverability of the instruments, and traction vector placement. The position of the patient will depend on the type of surgery, the personal preferences of the surgeon and the specific workplace in question. Correct initial placement of the patient avoids subsequent postural adjustments during surgery, which can increase both surgical and recovery times.
