16.2 Responses to Pain

Sympathetic Nervous System

The autonomic nervous system contains the sympathetic and parasympathetic nervous systems and regulates the involuntary physiologic responses of the body (Figure 16.5). The role of the sympathetic nervous system is to respond to perceived stressful or dangerous situations. The main response from the sympathetic nervous system is the fight-or-flight response, which triggers the body to either run away from or fight a perceived threat. For example, the body may perceive an encounter with a wild animal as a threat. The sympathetic nervous system will activate and tell the person to run away from the animal to safety. The fight-or-flight response may not be activated in perceived less stressful situations, but the body may still illicit a sympathetic response (Yeater et al., 2021). For example, a patient may be experiencing postsurgical pain even with pain medication. The sympathetic nervous system may respond to the pain by elevating the heart rate and blood pressure.

The sympathetic pain response involves many automatic bodily functions such as:

• enlarging pupils to improve vision;
• slowing digestion to allow the body to use energy in other places; and
• increasing heart rate and blood pressure to improve circulation (Cleveland Clinic, 2022b).

Nurses may notice these nonverbal signs of pain in a patient even before the patient states they are in pain. Noticing sympathetic pain responses is especially important in patients who cannot communicate their pain. Patients who are unconscious, confused, nonverbal, young, or cognitively impaired may not be able to adequately express their pain.

Parasympathetic Nervous System

The parasympathetic nervous system opposes the sympathetic nervous system and regulates the automatic bodily functions in times of rest and relaxation. Once the perceived stress or threat is gone, the parasympathetic nervous system takes over and returns the body to its normal functioning (Cleveland Clinic, 2022a).

The parasympathetic response includes:

• constricting pupils to limit light;
• producing saliva and mucus to assist in digestion and breathing;
• lowering heart rate and blood pressure to reduce workload;
• directing energy toward digestion to help break down food;
• directing the pancreas to create insulin to regulate blood sugar; and
• relaxing muscles to assist with urination and defecation (Cleveland Clinic, 2022a).

These responses indicate to the nurse that the patient is experiencing adequate pain relief. In the same way that the nurse observes sympathetic responses to detect a patient’s pain, the nurse may observe parasympathetic responses to determine if pain interventions are effective (Figure 16.5).

Figure 16.5 The parasympathetic and sympathetic divisions of the autonomic nervous system have opposite effects on various systems. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Vital signs can be an indicator of pain, and nurses can use vital sign measurements along with the patient’s response to determine if pain interventions are effective. Measuring vital signs as an indicator of pain can be especially useful for patients who cannot verbalize their pain. Pain can cause an increase in blood pressure, heart rate, and respiratory rate. Abnormal vital signs can occur without pain, so it is important that nurses perform other methods of assessment for pain as well. Nurses can also measure vital signs to determine if they have normalized after pain interventions. For example, if a patient has elevated blood pressure and is exhibiting signs of pain, the nurse can assess their blood pressure after pain medication has been given to ensure that it has normalized. This can help indicate that the pain interventions are effective.

Vocalization

Patients will sometimes use sounds, noises, and words to express pain. This is called vocalization; and it most often occurs in acute pain of varying severity. Vocalization of pain includes crying, screaming, moaning, gasping, or grunting (Helmer et al., 2020). Patients can vocalize their pain by using pain rating scales. Asking patients to rate their pain on a numeric scale can be an effective way to assess patients for pain. Patients can also vocalize pain descriptors such as severity, duration, location, and type of pain.

The use of vocalization to express pain is used often in younger children (Helmer et al., 2020). Younger children have limited communication when trying to express pain. The most common way for infants to express discomfort is by crying. Older children may be capable of stating their pain using appropriate pain scales (Figure 16.7), such as the Wong-Baker FACES Pain Rating Scale, but may still use crying or yelling to express pain (Venable, 2018).

Figure 16.7 A pain rating scale like this one can be used with patients who are unable to speak as referent communication. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Facial Expression

Facial expressions not only demonstrate emotions such as happiness, fear, or sadness, they can also demonstrate pain. Frowning, closing eyes, clenching teeth, opening the mouth, biting lips, grimacing, furrowing eyebrows, and scowling can all be used to express pain (Figure 16.8) (Cho & Hong, 2020).

Figure 16.8 Facial expressions such as grimacing, furrowing eyebrows, and closing eyes are a common way for patients to express pain. (credit: “The pain is brutal for these Marines 150306-M-IN448-056.jpg” by Sgt. Matthew Callahan/Wikimedia Commons, Public Domain)

Some research shows that social context can change the way a person expresses pain (Kappesser, 2019). For example, a young child may cry and use facial expressions to demonstrate pain around their parents. However, they immediately stop crying and try to smile when their older sibling comes into the room because they want to appear more mature. Another example is a person feeling comfortable enough to show facial expressions of pain in the presence of their partner rather than in front of a colleague or stranger (Kappesser, 2019). Patients may not feel comfortable showing facial expressions when in pain. They may try to hide their facial expressions in the presence of healthcare providers. It is important that nurses always help patients feel comfortable expressing their pain.

Body Movement

Patients may demonstrate pain through movement such as guarding, touching the location of the pain, withdrawing from touch, or tremors (Cho & Hong, 2020). Nurses may notice muscle tension and resistance to examination of the painful location.

Children often show pain through withdrawal of touch. While they may seek the comfort of their parents, they will often resist someone touching or manipulating the painful area due to fear of touch causing more pain. This can be difficult for nurses to assess the location of pain. Severe pain may require pharmacological interventions prior to assessment of the location of pain. Nurses must be mindful of the location of pain when doing a physical assessment. Visual assessment, diagnostic imaging, and descriptors of pain from the patient can help provide a comprehensive pain assessment without touching the painful area.

Social Interaction

The way that patients interact with others can change when they are in pain. Patients in chronic pain may withdraw from social interactions and become isolated. This can make the pain worse and contribute to deteriorating physical health in patients (Bannon et al., 2021). When patients are in pain and around others, they may appear quiet, reserved, and uninterested (Oommen & Shetty, 2020). Nurses can educate patients that these social interactions are a normal response to pain and help them verbalize to their loved ones that these negative emotions are responses to pain. It is important that patients are able to verbalize their pain in social situations, so they do not become socially isolated and withdrawn. Research has shown that supportive social environments can help patients cope with pain (Bannon et al., 2021).

Negative Emotion

Pain is an unpleasant sensation and associated with negative emotions. Negative emotions can include anger, frustration, fear, anxiety, depression, guilt, and sadness. Negative emotions can make it difficult to complete daily activities and can lead to social withdrawal. Everyone can feel negative emotions and they are not always connected to pain. However, it is important for patients to understand that pain can bring on negative emotions, especially anxiety and depression. If patients are not able to cope with negative emotions in healthy ways, it can lead to unhealthy consequences (Scott, 2022).

Accepting emotions and finding healthy coping mechanisms is essential to reducing pain and preventing negative consequences. Healthy coping mechanisms for negative emotions can include acceptance and understanding of the emotions, exercise, meditation, and lifestyle changes (Scott, 2022).