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Page 2 of 13 Gharagozloo. Mini-invasive Surg 2020;4:8 I http://dx.doi.org/10.20517/2574-1225.2019.62

For robotic thoracic surgical patients, minimizing pulmonary complications is the key to decreasing
morbidity. Studies have shown that simple deep breathing and coughing in the postoperative period
can effectively prevent complications such as atelectasis and pneumonia. The ultimate goal is to clear
secretions, maintain expansion of the lung, and decrease the complications associated with pulmonary
collapse. This goal is achieved by the patient’s ability to cough and deep breath, as well as the adjunctive
measures of spirometry, chest physiotherapy, and bronchoscopy. In turn, effective clearance of secretions
with cough and early mobilization are attained primarily by optimal pain control. Control of pain is the
core requirement for all postoperative measures in robotic thoracic surgical patients. Once the pain is
controlled, the morbidity associated with thoracic surgery is decreased.

PATHOPHYSIOLOGY OF PAIN
As defined by the International Association for the Study of Pain, pain is both the sensory and the
emotional experience that is associated with actual or potential tissue damage, and it is described in
[1]
terms of that damage . The unique and individual nature of pain perception stems from the fact that the
sensory experience is also associated with an individual’s affective and cognitive response. As a result of the
complex interaction between the pain stimulant and the individual’s unique response to the stimulant, the
cause and effect relationship between actual tissue damage and perception of pain is not constant among
individuals.

The pain pathway begins with nociception. Nociception is the process whereby certain stimuli (chemical,
mechanical, or thermal) activate a specific physiologic neural pathway. Nociceptors are the peripheral
nerve endings of sensory neurons and supply skin, muscles, joints, and other tissues. These nerve endings
are attached to axons, which communicate with the spinal cord or brainstem nuclei. The faster conducting
myelinated axons or A-delta fibers are responsible for the shorter-lived but higher-intensity pain sometimes
referred to as “first pain”. The slower conducting unmyelinated axons or C fibers produce the duller and
[2]
more prolonged pain sensation known as “second pain” .
Four processes lead to pain perception: (1) transduction; (2) transmission; (3) modulation; and (4)
perception.

(1) Transduction: Transduction takes place in the peripheral nerve endings, where a stimulus is converted
to electrical activity.

(2) Transmission: During transmission, the electrical activity is conducted through the nervous system.
Axons from peripheral sensory neurons transmit impulses to the spinal cord, where they synapse with
second-order neurons. Spinal second-order neurons project to different brainstem and diencephalic
structures. In turn, neurons from these structures project to the various cortical sites responsible for
sensation.

(3) Modulation: During modulation, the neural input, and thereby the pain process, is altered. Modulation
occurs in the dorsal horn of the spinal cord.

(4) Perception: During the phase of perception, the neural activity in a somatosensory pathway results
in the subjective sensation of pain. Perception results from the activation of primary and secondary
[3]
somatosensory and limbic cortices .
With tissue damage, nociceptors are stimulated. The initial stimulation of the nociceptors as the result of
tissue damage leads to enhanced response of these receptors and increased sensitivity to further stimuli.