**2. Pain assessment in ICU patients**

It is of vital importance that the pain be assessed properly so as to manage it well. As the International Association for the Study of Pain also states, "the inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment" [17]. Hence, the ICU physicians must learn to reliably detect pain, using assessment methods adapted to a patient's diminished communication capabilities. The pain assessment tools are mainly divided depending on the patient's ability to communicate or not. In later circumstances, clinicians should consider patients' behavioral reactions as surrogate measures of pain, as long as their motor function is intact [18]. Detection, quantification, and management of pain in critically ill adults are the priorities and have been the subject of research for the last two decades [19].

Pain assessments should include location, characteristics, severity, onset, progression, duration, quality, radiation, alleviating and exacerbating factors, and effects of previous therapies. Pain should be assessed by self-reporting scales in patients able to communicate, or by behavioral pain scores in patients unable to communicate. There are many self-report pain scales and behavioral pain scales developed for use in intensive care unit adult patients, which unfortunately are not always routinely used in the ICU. This self-reporting of their pain is the gold standard of pain assessment and provides the valid measurement of pain [20]. The commonly used pain intensity scales are the Numeric Rating Scale (NRS) and Visual Analogue Scale (VAS) while Behavioral Pain Scale (BPS) is considered to be an alternative tool for assessing pain in sedated and mechanically ventilated patients. The BPS assesses pain through the evaluation of facial expression, upper limb movements and compliance with mechanical ventilation. Another behavioral scale called the Critical-Care Pain Observation Tool (CPOT) may also be used.

There has been reluctance to use surrogates or individuals who make medical decisions when patients cannot do, to report patients' pain, due to their emotional attachment to these patients. They have a potential for overestimating pain. In SUPPORT study, it is concluded that surrogates can identify the patient's pain 73% of the time and accurately estimate its severity of pain 53% of the times [21].

The following pain scales will be useful in awake and cooperative patients:

#### **2.1. Visual analogue scale (VAS)**

with the patient about treatments and invasive procedure plans even when patients are not

It is an important contributing factor for increased pain response in ICU patients. In burns patients, it is a well-realized fact that if these patients do not have proper night sleep, the intensity of pain during the day time is higher [16]. Sleep deprivation in the ICU patients can result from psychological states, bright lighting, noise from ventilators and monitors, and disrupted circadian rhythms [14]. ICU patients' sleep will be improved by reducing exposure to bright light, reducing ambient noise, respecting circadian rhythms and using appropriate sedative hypnotics.

It is of vital importance that the pain be assessed properly so as to manage it well. As the International Association for the Study of Pain also states, "the inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment" [17]. Hence, the ICU physicians must learn to reliably detect pain, using assessment methods adapted to a patient's diminished communication capabilities. The pain assessment tools are mainly divided depending on the patient's ability to communicate or not. In later circumstances, clinicians should consider patients' behavioral reactions as surrogate measures of pain, as long as their motor function is intact [18]. Detection, quantification, and management of pain in critically ill adults are the priorities and

Pain assessments should include location, characteristics, severity, onset, progression, duration, quality, radiation, alleviating and exacerbating factors, and effects of previous therapies. Pain should be assessed by self-reporting scales in patients able to communicate, or by behavioral pain scores in patients unable to communicate. There are many self-report pain scales and behavioral pain scales developed for use in intensive care unit adult patients, which unfortunately are not always routinely used in the ICU. This self-reporting of their pain is the gold standard of pain assessment and provides the valid measurement of pain [20]. The commonly used pain intensity scales are the Numeric Rating Scale (NRS) and Visual Analogue Scale (VAS) while Behavioral Pain Scale (BPS) is considered to be an alternative tool for assessing pain in sedated and mechanically ventilated patients. The BPS assesses pain through the evaluation of facial expression, upper limb movements and compliance with mechanical ventilation. Another behavioral scale called the Critical-Care Pain Observation Tool (CPOT) may also be used.

There has been reluctance to use surrogates or individuals who make medical decisions when patients cannot do, to report patients' pain, due to their emotional attachment to these patients. They have a potential for overestimating pain. In SUPPORT study, it is concluded that surrogates can identify the patient's pain 73% of the time and accurately estimate its

The following pain scales will be useful in awake and cooperative patients:

able to verbally respond [15].

62 Pain Management in Special Circumstances

**2. Pain assessment in ICU patients**

severity of pain 53% of the times [21].

have been the subject of research for the last two decades [19].

*1.2.3. Sleep deprivation*

In this, the patient can see and describe the severity of pain on a scale of 0–10. Zero for no pain and 10 for maximum pain (**Figure 1**).

#### **2.2. Numerical rating scale (NRS)**

Patients rate pain by writing on a 10-point scale (**Figure 2**) (0, no pain; and 10, most severe pain).

#### **2.3. Verbal rating scale (VRS)**

In this scale, the patient can verbalize the pain in four grades. Grade 1 indicates the absence of pain, whereas severe pain is indicated by grade 4.

Pain scales and tools are used for patients unable to communicate.

#### **2.4. Behavioral pain scale (BPS)**

It is a clinical observational score depending upon the patient's facial expressions, upper limbs posturing, and tolerance of the controlled mechanical ventilation (**Table 1**). This score ranges from 3 to 12, and a score of >6 require pain management [22].

**Figure 1.** Visual analogue scale with its component.

**Figure 2.** Numerical rating scale and its description of pain.


they receive. However, this technique requires awake and orientated patients which make use of PCA limited in ICU patients. In combination with intravenous paracetamol and pro-

Acute Pain Management in Intensive Care Patients: Facts and Figures

http://dx.doi.org/10.5772/intechopen.78708

65

It is inferior to the PCA but still can be useful, as nurses can administer the analgesia quickly

Analgesia techniques are used in ICU-selected trauma patients and surgical procedures. Epidural analgesia is probably the most commonly used regional anesthetic technique in the ICU. It is more useful in critically ill postoperative thoracic, abdominal, major vascular surgery, orthopedic surgery and trauma patients. Positioning patients during catheter insertion is a challenge for using regional anesthesia in ICUs. The main disadvantages of epidural and regional analgesia are the rare but catastrophic complications such as infection, epidural hematoma formation and nerve damage, which can occur in ICU patients who have a high

The combination of intravenous opioid PCA, paracetamol and regional anesthesia techniques is multimodal analgesia which decreases the total opioid analgesia consumption and hence decreasing the side effects and better patient comfort. The NCA proved to not be superior to

Opioids are the main medications used for analgesia in ICU patients due to potency, concomitant mild sedative and anxiolytic effects. It can be administered by multiple routes. The commonly use opioids include Fentanyl, Remifentanil, and Morphine. The choice of opioid and the dosing should be individualized based on potency, pharmacokinetics and pharmaco-

It is the most frequently used medication in cancer patients. It is the standard by which other opioids are compared. Morphine is directly extracted from opium poppies; it stimulates the release of histamine which produces allergic and vasodilation-induced cardiovascular instability. Initial bolus intravenous (IV) morphine 2 mg dose administered slowly over 4–5 min then can be titrated with 1–2 mg every 10–15 min till adequate analgesia is achieved. Continuous IV morphine can be administered with an initial 2–5 mg bolus dose followed by 1 mg/h. Morphine is primarily metabolized in the liver and it is excreted through kidneys. It has active metabolites; morphine-3-glucuronide and morphine-6-gluconoride. Accumulation of these metabolites in renal insufficiency can produce opioid toxicity and adverse effects such as nausea, sedation, respiratory depression myoclonus and

dynamics, adverse effect, patient comorbidities and organ dysfunction [25].

paracetamol, the opioid consumption is significantly less [23].

**3.3. Regional (nerve blocks) and neuraxial (spinal or epidural)**

**3.2. Nurse-controlled analgesia (NCA)**

when required or during the procedures.

risk of developing these complications [24].

**4.1. Morphine**

seizures (**Table 2**) [25].

PCA and increases the rapid response team activation.

**4. Analgesic medications used in ICU patients**

**Table 1.** Behavioral pain scale and its components.

#### **2.5. Critical care pain observation tool (CPOT)**

This pain assessment tool has four clinical components, facial expressions, body movements and muscle tension and compliance with the invasive mechanical ventilation. CPOT score ranges from 2 to 8. A score of more than 2 requires pain management.
