**5. Venous air embolism**

Low venous pressure and open ventilation are required for the air to enter the venous system as compared with the atmospheric pressure.

This most often occurs during the neurosurgery operations in a sitting position.

In addition, poor surgical technique may increase the formation of air embolism.

Factors affecting air embolization are as follows:


Slowly entering a small air bubble has usually minimal physiological importance. In this case, venous air bubbles are taken out from lungs based on increased compensator pulmonary artery pressure (PAP). If this situation exceeds the capacity of lung removal, PAP increases, cardiac output (CO) decreases and hearth failure occurs. If balanced, namely, if venous air input is equal to pulmonary removal, PAP reaches a plateau.

**6.4. Preanesthesia assessment in arthroplasties**

avoided from excessive extension of the neck joint.

• The patient's age, weight, body mass index and vital signs (blood pressure, heart rate, pulse rate, body temperature, number of breaths, (depth breathing)) of the patient are

Anesthesia Management in Total Hip Replacement http://dx.doi.org/10.5772/intechopen.76366 55

• In these patients, the underlying etiology is mostly osteoarthritis or rheumatoid arthritis. Therefore, examination of the cervical and lumbar vertebrae is especially important for

• The cervical spine mobility should be checked to evaluate any restriction and assessed for intubation difficulty. Also, under the anesthesia and during intubation, attempts should be

• Osteoarthritis may lead to nerve root compression in the spine. Cervical spine and temporomandibular joint may be involved in patients with rheumatoid arthritis. In the presence of atlantoaxial joint subluxation, diagnosis can be made radiologically. During intubation, subluxation of the atlantoaxial joint may cause foramen magnum protrusion to odontoid process, reducing vertebral blood flow and compressing the spinal cord or brain. Intubation must be done by stabilizing the neck. A vigilant intubation technique may be preferred in some patients. It may be easier to prefer regional anesthesia in this group of

• Because of multiple joint involvements in rheumatoid arthritis, it should be taken into ac-

• Since most of patients undergoing arthroplasty are older, having cardiac, respiratory, cerebral, renal and endocrine diseases, perioperative and postoperative morbidity and mortal-

MET's (classification of metabolic equivalent) meaning is that 40 years old, 70-kg man expresses oxygen consumption at rest. It is considered to be over 4 in the MET evaluation, can go uphill, go up 2 stories of stairs, walk straight on the road at 6 km/h, run short distance, do heavy work at home and participate in moderate activities. Patients with MET ≥4 are consid-

count when placing intravenous catheters to the hand, wrist, foot, etc.

ity increase. Therefore, evaluation of systems is very important.

*6.4.1. The evaluation of cardiovascular system*

ered to be good in terms of functional capacity.

• 3 MET mild housework, walking at 2–3 mph

• 1 MET resting, eating, toilet needs

• 4 MET 2-story climbing stairs

• Personal background. • Physical examination:

evaluated.

anesthesia.

patients [9].

300-ml air is fatal in adults. In animal trials, 1 ml/kg/min causes embolism signs; 3–8 ml/kg causes death. The earliest sign is cardiovascular collapse. Blood pressure decreases dramatically; sudden hypotension, tachycardia, arrhythmia and cardiac arrest occur in succession. CVP increases; a metallic sound is heard with the precordial or esophageal stethoscope. In case of this, characteristic "sound of the mill wheel" is heard. This sound can be heard in all precordium. Respiratory changes such as increased respiratory rate, irregularity and apnea can be seen.

#### **5.1. Diagnosis**

