Rapid onset

Adequate anaesthesia for surgery can be achieved in a very short time, perhaps as little as two minutes, as the drugs are placed into the cerebrospinal fluid, in direct contact with the spinal nerves.

Rapidity of onset can be an important factor in patient satisfaction, and in promoting efficiency of the operating list.

IMPORTANT! In some circumstances, rapid onset may be detrimental. This is discussed further in the section entitled Hypotension, within Disadvantages of Spinal Anaesthesia.

Dense block

Effective spinal anaesthesia provides a dense sensory blockade, usually affecting all dermatomes below the upper sensory level. Patchy or partial blockade is unusual. Spinal anaesthesia generally produces a denser and more reliable block than epidural.

Awake patient

Spinal anaesthesia offers the opportunity for the patient to remain awake during surgery. However, in practice, few patients choose this and anxiety about awareness is a common reason for patients to reject the technique. Patients need to be reassured that with modern sedation techniques (including target-controlled infusion of propofol), a lack of awareness and amnesia equivalent to general anaesthesia can be provided.

Avoids general anaesthesia

Many patients are keen to avoid the after effects of general anaesthesia. In particular, many patients will opt for spinal anaesthesia because of the reduction in incidence of nausea and vomiting and the lack of prolonged sedation in the immediate post-operative period.

Pain-free recovery

Many patients are anxious about waking from general anaesthesia in pain. The sensory block from spinal anaesthesia will usually last into the recovery period and many patients will find the promise of lack of pain reassuring. Appropriate analgesia can then be given as the spinal wears off.

Long-acting analgesia

Long-acting analgesics, such as diamorphine, can be added to the spinal drugs. This offers the promise of long-acting analgesia, even after the sensory and motor block of the spinal has worn off. In some cases, this may even be sufficient to avoid the need for any further opioid analgesia, potentially avoiding undesirable side effects.

Improved surgical field/reduced blood loss

The hypotension produced by spinal anaesthesia can reduce the amount of blood loss at the surgical site, with benefits for the surgeon and patient.

Reduced deep vein thrombosis (DVT) risk

The reduction in systemic vascular resistance results in increased flow to the lower limbs, reducing venous stasis, and thus reducing DVT risk.

Avoids risk of airway manipulation

There are many situations in which the anaesthetist may prefer to avoid manipulation or management of the airway. Spinal anaesthesia offers one way of achieving this.

IMPORTANT! Spinal anaesthesia is often suggested as a safe means of anaesthetizing the patient with a difficult airway. However, in the event of a complication, airway management may still become necessary. It remains necessary therefore to have an airway management plan in such cases.

Respiratory disease

The use of spinal anaesthesia can avoid the respiratory depressant effects of general anaesthesia and systemic opioids. However, respiratory function can be compromised by the motor block to the intercostal muscles, and so there is a fine balance to be had.

In mild or well-controlled well-controlled disease, the use of spinal anaesthesia is unlikely to be associated with a measurable difference in morbidity or mortality.

Cardiovascular disease

The ischaemic heart may benefit from the reduction in preload and afterload provided by a reduced systemic vascular resistance. However, it is important that the diastolic blood pressure is not allowed to fall too low, as this compromises diastolic coronary perfusion.

In patients undergoing lower limb revascularization, graft occlusion rate may be decreased by spinal anaesthesia, courtesy of the increased blood flow.

In mild or well-controlled disease, the use of spinal anaesthesia is unlikely to be associated with a measurable difference in morbidity or mortality.