Page 20 - Read Online

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

Furthermore, these concepts should be applied to the specific responses of the individual patient. Many
studies have focused on the patient undergoing a conventional thoracotomy. It is generally agreed that
thoracotomy is an extremely painful procedure that requires aggressive perioperative and postoperative
attention to pain management. Any inattention to pain invariably leads to such deleterious consequences as
atelectasis, pneumonia, DVT/PE, and subsequently prolonged hospitalization. To minimize complications,
it has been hypothesized that decreasing the size of the incision or “sparing” the muscles of the chest will
decrease the resulting pain. This commonly accepted hypothesis has not proven to be true. In fact, a recent
[7]
study by Ochroch et al. , 2005, compared patients undergoing a traditional postero-lateral thoracotomy with
those undergoing a muscle-sparing thoracotomy and found no difference in perceived pain up to 48 weeks
postoperatively.

There has also been recent work outlining the differences between a traditional thoracotomy and a
video-assisted surgery. In 1994, Landreneau compared 165 patients who underwent a postero-lateral
thoracotomy and 178 who underwent the Video-assisted Thoracic Surgery (VATS) technique. This
study found that less subjective pain was reported by the VATS group in the first year after surgery;
however, analgesic requirements were similar . In a smaller study also in 1994, a smaller study
[8]
[8]
reported similar findings comparing the two groups . However, in this study, the lower levels of
perceived pain by the VATS patients was noted only in the first few days after surgery. These studies are
[9]
substantiated by more recent ones, such as Li et al. , 2003, who found that, when compared to the postero-
lateral thoracotomy, VATS surgery was associated with significantly less shoulder dysfunction and pain
medication requirement in the early postoperative period. While some of the reasons for these differences
may be attributed in part to the smaller incisions, which presumably result in smaller amount of tissue
injury, the entire reasoning is more complex. Referring to the previous discussion about nociception, it
is not only the activation of the nociceptors that leads to hyperalgesia, but also the chemical mediators
[10]
that are released at the same time and contribute to the overall peripheral sensitization. Yim et al.
compared thoracotomy to VATS in relation to cytokine response. They found that not only did the
VATS group have significantly less analgesic requirement, but also that plasma levels of interleukin 6 and
interleukin 8, both pro-inflammatory cytokines, were reduced in the VATS group. Based on this study, it
appears that decreased humoral mediators may contribute to decreased sensitization following VATS. In
fact, VATS and thoracotomy may be similar as initial stimuli for nociceptors but the advantage of VATS
may be due to the lower level of sensitization and lessened response to the initial stimulus.

As robotic thoracic surgery further decreases the invasiveness of thoracic surgery, the principles of pain
management with VATS need to be applied and modified for robotic thoracic surgery.

PAIN MANAGEMENT
Preemptive analgesia
Successful pain management encompasses choices made in both the perioperative and postoperative
periods. Earlier pain control may prevent central sensitization. As explained above, beginning pain
management earlier will help to prevent central sensitization. There has been much attention paid recently
to the concept of preemptive analgesia. Preemptive analgesia is simply the theory that, by stopping
or decreasing the input of stimuli (nociception), one can prevent or decrease central sensitization,
and, in turn, achieve a decrease in overall pain. An extension to this concept is the hypothesis that, by
administering analgesia prior to nociception, it may be possible to decrease chronic pain syndrome.
Electrophysiologic data from animal studies have shown that administering low doses of an opioid such as
morphine prior to the introduction of a noxious stimulus can suppress spinal cord hyperexcitability. On the
other hand, administering that same opioid after the noxious stimulus does not result in the same degree of
suppression . As NMDA is implicated in the “wind up” phenomenon, it is thought that NMDA may play
[11]