Summary of study session VII 

In study session VII you learnt 

• Local anesthetics administered in the subarachnoid space block sensory, autonomic, and motor impulses as the anterior and posterior nerve roots pass through the cerebro spinal fluid (CSF). 
• Spinal anesthesia has advantage in maintaining patent air way, less expensive, decrease blood loss, better for diabetics, and other when it is not complicated. The disadvantages include risk of failure and the operation may outlast the, spinal anesthetic. Patient refusal, infection at the injection site, bleeding problem, severe hypovolemia, head injury, severe uncorrected anemia, allergy to local anesthetics are contraindicated to spinal anesthetics 
• The technique of administering spinal anesthesia will include preparation, position and performing spinal anesthetic injection phases. 
• Preparation of equipment/medications is the first step. A full set of general anesthesia preparation, making a pre anesthetic visit, preparing local anesthetics for the proposed level and length of procedure, having appropriate size and bevel spinal needle along with spinal kit should be prepared. 
• Prior to initiating a spinal block; all patients having spinal anesthesia must have a large intravenous cannula inserted and be given intravenous preloading (fluid) immediately before the spinal, attached to standard monitors and at any point during the administration maintain sterility. 
• The sitting and lateral decubitus position is the most utilized position for spinal anesthetic procedures. Sitting position encourages flexion and facilitates recognition of the midline, which may be of increased importance in an obese patient. The lateral decubitus position is more comfortable and more suitable for the ill or frail. 
• A line drowns between the highest points of the iliac crests will cross the fourth lumbar spine or the space between the fourth and fifth spines. Other vertebral levels may be identified from this point and marked. The midline is noted by moving your fingers from medial to lateral. 
• The spine is palpated and the patient's body position is examined to ensure that the plane of the back is perpendicular to that of the floor. The depression between the spinous processes of the vertebra above and below the level to be used is palpated; this will be the needle entry site. Remembering that the spinous processes course downward from the spine toward the skin, the needle will be directed slightly cephalad. 
• The bevel of the spinal needle should be directed laterally, so that the dural fibers that run longitudinally are spread rather than transected. 
• As the needle penetrates the ligamentum flavum an obvious increase in resistance is usually encountered. When the spinal needle goes though the dura mater, a “pop” and slight discomfort is often appreciated. Once this pop is felt, the stylet should be removed from the introducer to check for flow of CSF. 
• Anatomical structures that will be transversed in midline approach include skin, subcutaneous fat, muscle, supraspinous ligament, interspinous ligament, ligamentum flavum, epidural space, and dura matter, arachnoid matter & subarachnoid space (CSF). 
• Once CSF returns and clear, steady the needle with the hub of the spinal needle held firmly between the thumb and index finger of the left hand-the back of the left hand against the patient's back to prevent either withdrawal or advance of the spinal needle- the syringe containing the local anesthetic solution is firmly attached to the needle then inject. Never inject local anesthetic while the patient is complaining pain. 
• After unsuccessful attempts, consider converting to a general anesthetic. The more attempts, the more traumas, increasing the risk of a spinal/epidural hematoma. 
• Distribution of local anesthetic solutions within the subarachnoid space determines the extent (height) of the neural blockade produced by spinal anesthesia. The 3 most important factors in determining distribution of local anesthetics are baricity, position of the patient during and just after injection and the dose of local anesthetics.