**1. Introduction**

Postoperative pain is generally short term and acute in nature. It arises from injury of tissue which resulted from surgical procedures [1, 2]. Of all surgical procedures, thoracic and breast surgeries cause significant severe postoperative pain and suffering to patients [3]. For this reason, provision of adequate and effective postoperative pain relief is the paramount goal for thoracic and breast surgery patients during postoperative period. Inadequate pain management after surgery can be caused by several reasons including limited translation of current best available evidence to guide quality pain management in clinical praxis [4]. Standardised and streamlined

pain management of patients who undergo these surgeries also requires knowledge and concept of evidence-based interventions to assure the quality and success of the management.

#### **2. Postoperative pain after thoracic surgery**

Thoracic surgery involves several pain sensitive structures with a number of pain transmission and perception; hence, patients are expected to experience severe pain within the first 72 hours after surgery [5]. Arising from surgical approaches and intraoperative manipulations of the thoracic structures, pain after thoracic surgery is commonly acute in nature with high severity in the immediate postoperative period [5]. Some of the descriptors used by patients to describe pain after thoracic surgery may be suggestive of mixed pain (acute pain and neuropathic pain), which when not adequately managed can result in chronic pain [6, 7].

Post-thoracic surgery pain has a complex mechanism that mostly occurs due to nociceptive and neuropathic signals that originate from somatic and visceral afferents [8]. Nociceptors are stimulated by the skin incision, muscle retraction, rib retraction, stretched ligaments, costochondral joint dislocation, and intercostal nerves injury [9–11].

Due to intra- and postoperative thoracic surgical approach and manipulation, noxious stimuli are transmitted by the intercostal nerve from the structures of the chest wall and pleura cavity to the nociceptive neurons in the central nervous system [8, 12]. The ipsilateral dorsal horn of the spinal cord (T4–T10) receives nociceptive somatic signals after a surgical trauma (incision, retraction, etc.) to the thoracic area [8, 11]. Then, the afferents are transmitted to the limbic system and somatosensory cortices through the contralateral anterolateral system.

Surgical manipulations of the structures of the chest including the pleura, diaphragm, or bronchi also initiate visceral stimuli. Nociceptive visceral afferents stimulated from tissue injury around bronchi and visceral pleura are transmitted by the vagus and phrenic nerves, the noxious stimuli arising from the diaphragmatic pleura are transmitted via the phrenic nerve, while mediastinum, lungs, and mediastinal pleura noxious stimuli are transmitted by the vagus nerve to the pain receptor [8]. Noxious stimuli resulting from surgical incision-induced tissue damage around the surgical sites are transmitted to the pain receptor in the central nervous system. These transmissions activate and sensitise nociceptor to develop an inflammatory response which further stimulates nociceptors and amplifies the transmission of pain, thereby increasing pain perception and hyperalgesia or increasing pain intensity at the surgical site [12].

Furthermore, noxious stimuli as afferent impulses resulting from visceral pleura irritation are referred to the ipsilateral shoulder by the phrenic nerves and become the major cause of ipsilateral shoulder pain after thoracic surgical procedures or postthoracotomy shoulder pain [9–11]. Additionally, pain development is exaggerated by brachial plexus stretching and posterior thoracic ligaments distraction [11, 13]. Shoulder pain after thoracic surgery is often developed in the early stage or immediately after surgery lasting for a few days with usually moderate to severe intensity and mostly described by patients as an ache [14].

Compression and irritation of the intercostal nerves by chest tubes and surgical stripping or residual pleural blood may further activate inflammatory response [8, 9]. Consequently, inflammatory mediators (e.g. prostaglandins, histamine, bradykinin,

*Non-Pharmacological Management of Acute Pain after Breast and Thoracic Surgery DOI: http://dx.doi.org/10.5772/intechopen.109863*

and potassium) are released [8–11]. The release of prostaglandins, neurotrophins, and interleukins contributes to the activation of nociception and sensitisation [12].

Damage to nerves, most often the intercostal nerve injury resulting from mechanical damage, rib retractor, compression, or rib fractures as well as phrenic nerve irritation from chest tube placement has been reported in the literature as major contributors to neuropathic pain. Chest tubes after thoracic surgery also cause severe pain in cases where the tubes compress the intercostal nerves. In addition, the presence of sutures or wires passed around the ribs and closer to the neurovascular bundle may result in intercostal nerves damage, thus leading to neuropathic pain [11].

In a nutshell, for most patients undergoing thoracic surgery, there are several components and mechanisms that contribute to pain development. This may be a combination of acute, somatic, visceral, and neuropathic pain. The pain may also arise from incision, rib removal or damage, injury to the intercoastal nerve, pulmonary parenchyma incision and the presence or continuous irritation from chest tubes.

#### **3. Postoperative pain after breast surgery**

At some point in breast cancer treatment trajectory, patients may undergo surgery [15]. Hence, surgery is a treatment that has become the first line of approach against breast cancer. Surgery can be either breast conserving, such as lumpectomy, or a complete removal of all breast tissue, called mastectomy. The specific surgery depends on the stage and type of tumour a patient has [16]. Women with stage I, II, and III breast cancer can be treated with breast surgery including breast conserving surgery for stage I breast cancer and mastectomy for stage II and III breast cancer [17].

Irrespective of the type of breast surgery, patients experience postoperative pain. The pain responses usually stem from the surgical procedure itself. In the immediate postoperative period, the pain experienced by breast surgery patients is usually nociceptive and acute in nature and may be moderate or severe in nature [18]. Nociceptive pain is a type of pain that is characterised by localisation around the damaged tissue and resolves within the normal healing time [19], while acute pain is a type of pain characterised by sudden onset after tissue damage and high severity [18].

The nature of postoperative pain that occurs immediately after mastectomy is complex and multimodal in nature. For pain to be experienced, an external stimulus is usually transported via thin myelinated (i.e. A-δ fibres) and non-myelinated (i.e. C-fibres) fibres whose receptivity are determined by the control of sodium/calcium or potassium channels [20]. When the stimuli transported through C-fibres are more than those transported in A-δ fibres, little or no pain is experienced and vice versa [21]. This type of pain is constantly moderated by the brain stem and cortical pathways, and there may be a facilitation or inhibition of pain that further regulates both the sensory and emotional aspects of pain [19].

With pain after mastectomy, the severity experienced by individuals varies based on the degree of modification of the contact between the synapses, nociceptors, neurons at the dorsal horn of the spinal cord, and other nociceptive signal modulation structures in the central nervous system [20]. Depending on the severity of the pain, pain management regimen is prescribed [19] that may require the use of strong pain management regimen including opioids [22].
