Pain Assessment and Management in the Critically Ill Patient


Published: 04 August 2021

This article will discuss how to assess and manage acute pain in critically ill patients.

Pain is a 'complex subjective phenomenon associated with actual or potential tissue damage’ (Prevost 2009).

Pain should be predicted in all patients and every action should be questioned for its possibility to cause pain or discomfort to the patient. Anticipation of pain allows alternative strategies to be considered or pre-emptive analgesics given (Mallet et al. 2013).

Acute Pain v Chronic Pain

Pain can be either:

  • Acute: Pain that occurs during the expected period of healing and lasts for less than 12 weeks, or
  • Chronic: Pain that continues after the expected period of healing and lasts for more than 12 weeks in duration.

(DoH UK 2010)

Pain in most critically ill patients is considered acute because it usually has an identified cause. For example, it may be associated with a procedure during the patient’s stay on the ward or postoperatively (Prevost 2009).

Causes of Pain in Critcally Ill Patients

Critically ill patients are particularly vulnerable to pain and discomfort due to the severity of their health conditions, as well as diagnostic and treatment interventions. Potential causes include:

  • Incisions
  • Surgery
  • Trauma
  • Cannulation
  • Catheterisation
  • Airway suctioning
  • Endotracheal tubes
  • Non-invasive ventilating devices
  • Drains/drain removal
  • Wounds/dressing changes
  • Physical therapy
  • Prolonged immobility
  • Constipation
  • Sleep deprivation
  • Disturbances such as awakening and manipulation for repositioning
  • Patient’s inability to report pain.

Critically ill patients should be assessed for pain on a regular basis and the frequency of assessment should be patient-specific and adjusted according to their risk.

However, health professionals often underestimate patients' pain. This is one of the main reasons for inadequate pain management (Hamill-Ruth & Marohn 1999; Watt-Watson et al. 2001).

Potential Barriers to Adequate Pain Management

  • Fear that the patients will become addicted to opiates
  • Reluctance or inability of patients to request analgesia
  • Lack of regular and frequent assessment of pain and pain-relief interventions
  • Belief that pain is not harmful but a ‘normal’ response to surgery
  • Inadequate patient education
  • Lack of understanding of the need to titrate analgesics to meet patients' needs.

(Macintyre & Schug 2007)

The Effects of Untreated or Unmanaged Pain

Untreated pain can pose serious consequences for the already compromised critically ill patient and can affect most body systems (Prevost 2009). Untreated pain may have the following effects:

  • Respiratory: Decreased respiratory effort, sputum retention and pneumonia
  • Cardiovascular: Hypotension, tachycardia, increased peripheral vascular resistance and pulmonary embolism
  • Gastrointestinal: Decreased gastric emptying and gut motility, leading to ileus and reduced function
  • Urinary retention
  • Immune system: Pain can cause suppression of immune function predisposing to infection
  • Metabolic: Reduced anabolic hormone, leading to increased protein breakdown, hyperglycaemia, impaired wound healing and increased muscle breakdown
  • Musculoskeletal: Pain can lead to muscle spasm, muscle wasting and immobility
  • Psychological: Pain can cause fear, anxiety, helplessness and sleep deprivation, all leading to increased pain
  • Central nervous system: Untreated pain can lead to chronic pain due to central sensitisation.

(Macintyre & Schug 2007)

Pain Assessment in the Critically Ill Patient

Careful consideration needs to be given to the assessment method chosen for critically ill patients because they are often unable to participate in the pain assessment process.

Below are some methods of assessing pain in critically ill patients:

Self-Report (Numeric Rating Scale)

This is considered the most reliable method of pain assessment.

This method is offered to patients who are able to communicate, even if not verbally (Puntillo et al. 2009). A numerical rating scale (NRS) with a standard scale of, for example, 0-10 (where 0 = pain-free and 10 = worst pain you can imagine), can still be used if the patient is able to point to the scale or nod at simple commands (Mallet et al. 2013).

Pain scale

Behavioural Pain Scale (BPS)

The behavioural pain scale was developed to allow a more quantifiable assessment of pain (Payen et al. 2001) in patients who cannot self-report pain and are unable to be assessed with the numeric rating scale.

As many critically ill patients are unable to cooperate with a numeric rating scale, they may require an alternative assessment. The BPS involves looking for pain-related behaviours and physiological indicators in order to plan treatment, such as:

Behavioural indicators:

  • Facial grimacing
  • Limb flexion
  • Ventilator dyssynchrony.

Physiological indicators:

  • Hypertension
  • Tachycardia
  • Tachyphoea
  • Lacrimation.

(Jocabi et al. 2002)

However, physiological signs alone are a poor assessment of pain in the critically ill. That is because these signs are often present regardless of pain.

Therefore, pain assessment should be sure to include observations of behaviours and physiological signs, with any change in the physiological indicators after administering analgesics to be monitored (Jocabi et al. 2002).

Management of Pain

When pain is indicated in the patient, follow the WHO analgesic ladder (WHO 1990) and take into account the patient’s comorbidities and your organisation’s usual selection of analgesics.

An analgesic regimen tailored specifically to the patient will take into account:

  1. The patient's pain levels
  2. Appropriate analgesics for the patient
  3. Documentation of each step of the care and assessment provided to the patient (this helps to provide an accurate record, monitor effectiveness of treatment and also facilitates continuity of care).

(Mallet et al. 2013)


Effective pain management is an important element of the nurses’ role. The effects of inadequate pain management are significant and can lead to delayed healing and prolonged recovery. The nurse, therefore, must be competent in pain assessment methods/tools and be able to administer and evaluate pain management techniques.

  • Department of Health 2010, Essence of Care 2010, DoH,
  • Gunning, K 2010, 'Management of Pain in the Intensive Care Patient', Journal of the Intensive Care Society, vol. 11, supp. 1, pp. 4-7,
  • Hamill-Ruth, R J, Marohn, M L 1999, 'Evaluation of Pain in the Critically Ill Patient', Critical Care Clinics, vol. 15, pp. 35-54, viewed 8 May 2018,
  • Jacobi J, Fraser, G L, Coursin, D B, Riker, R R, Fontaine, D, Wittbrodt, E T, Chalfin, D B, Masica, M F, Bjerke, H B, Coplin, W M, Crippen, D W, Fuchs, B D, Kelleher, R M, Marik, P E, Nasraway Jr, S A, Murray, M J, Peruzzi, W T & Lumb, P D 2002,'Clinical Practice Guidelines for the Sustained Use of Sedatives and Analgesics in the Critically Ill Adult', Critical Care Medicine, vol. 30, no. 1, pp. 119-141, viewed 8 May 2018,
  • Macintyre, P E & Schug, SA 2007, Acute Pain Management, 3rd edn, Saunders Elsevier, Philadelphia, PA.
  • Mallet, J, Albarran, J & Richardson, R 2013, Critical Care Manual of Clinical Procedures and Competencies, Wiley-Blackwell, Oxford.
  • Payen, J F, Bru, O, Bosson, J L, Lagrasta, A, Novel, E, Deschaux, I, Lavagne, P & Jacquot, C 2001, 'Assessing Pain in Critically Ill Sedated Patients by Using a Behavioural Pain Scale', Critical Care Medicine, vol. 29, no. 12, pp. 2258-63, viewed 8 May 2018,
  • Prevost, S S 2009, Relieving Pain and Providing Comfort, In: Gonce Morton, P & Fontaine, D K (eds), Essentials of Critical Care Nursing: A Holistic Approach, Wolters Kluwer Health/Lippincott Williams & Wilkins.
  • Puntillo, K, Pasero, C, Li, D, Mularski, R A, Grap, M J, Erstad, B L, Varkey, B, Gilbert, H C, Medina, J & Sessler, CN 2009, 'Evaluation of Pain in ICU Patients', Chest, vol. 135, no. 4, pp. 1069-74, viewed 8 May 2018,
  • Watt-Watson, J B, Stevens, B, Garfinkel, P, Streiner, D & Gallop, R 2001, 'Relationship Between Nurses Knowledge and Pain Management Outcomes for Their Postoperative Cardiac Patients', Journal of Advanced Nursing, vol. 36, no. 4, pp. 535-45, viewed 8 May 2018,
  • World Health Organisation 1990, 'Cancer Pain Relief and Palliative Care: Report of a WHO Expert Committee', World Health Organisation Technical Report Series, no. 804, pp. 1-75, WHO, Geneva, Switzerland.


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Lydia Nabwami View profile
Lydia Nabwami is registered nurse who has worked in various healthcare settings including cardiac ward, cardiac critical care unit (ITU), general ITU, A&E department, nursing homes and community nursing. She uses her experience as a RN to write well-researched content that helps to attract and motivate audiences. Lydia is also a freelance writer for hire with specialisation in health writing and has helped numerous companies with their content needs. Her work has appeared on sites such as Caring Village, Reachout, Lisa Nelson RD and more. When she isn’t writing, you can find her listening to motivational speeches, keeping active or playing with her two daughters. Contact Lydia or visit her website at for more information on her services.