Physiotherapy approaches for pain control in patients who are critically ill

Abstract

Pain is a significant challenge in critical care settings, affecting patient outcomes, recovery time, and quality of life. While pharmacological interventions remain the cornerstone of pain management in intensive care units (ICUs), they are associated with numerous adverse effects including respiratory depression, delirium, and prolonged ICU stays. To examine evidence-based physiotherapy approaches that can effectively complement traditional pain management strategies in patients who are critically ill. We conducted a comprehensive literature review of physiotherapy modalities used for pain control in ICU settings. The review focused on six key interventions: Early mobilization, positioning, postural management, manual therapy techniques, thermotherapy, transcutaneous electrical nerve stimulation (TENS), and photobiomodulation (PBM). Evidence supports the efficacy of physiotherapy interventions in reducing pain intensity and improving patient comfort in critical care environments. Early mobilization prevents complications of immobility while indirectly reducing pain through improved circulation and endorphin release. Proper positioning techniques alleviate pressure on painful areas and reduce the incidence of pressure injuries. Manual therapy provides pain relief through neural mobilization and muscle relaxation. Thermotherapy offers significant analgesic effects with minimal side effects. TENS and PBM demonstrate promising results as nonpharmacological pain management options, with PBM showing efficacy through its impact on cellular metabolism and neural pathways. Evidence supports physiotherapy interventions as effective nonpharmacological adjuncts to conventional pain management in critical care, demonstrating efficacy through multiple modalities that enhance patient comfort while potentially reducing opioid requirements.

Key Words: Pain; Critically ill patients; Intensive care unit; Physiotherapy; Early mobilization; Nonpharmacological interventions; Patient comfort; Rehabilitation; Mechanical ventilation; Sedation reduction

Core Tip: Physiotherapy interventions offer effective nonpharmacological approaches to pain management in intensive care unit patients, potentially reducing reliance on opioids and their associated complications. This review highlights six evidence-based modalities-early mobilization, positioning, manual therapy, thermotherapy, transcutaneous electrical nerve stimulation, and photobiomodulation-that can complement conventional analgesic strategies. These interventions demonstrate efficacy in reducing pain intensity while improving patient comfort through multiple physiological mechanisms, presenting viable options for comprehensive pain management protocols in critical care settings.

INTRODUCTION

According to the International Association for the Study of Pain, pain is an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. Furthermore, pain is a subjective experience shaped by biological, psychological, and social variables. It can manifest in multiple ways, and the inability to articulate it does not indicate its absence. Individuals with one or multiple significantly abnormal physiological indicators were critically unwell[1-2].

As noted by Maley and Mikkelsen[3], more than 5.7 million people with this medical diagnosis are admitted to specialized hospital departments for critical care annually across the United States, with additional millions receiving such treatment globally.

The origins of severe discomfort during critical illness involve diverse and interconnected elements. Although no factor is universally modifiable, systematically addressing all possible contributors can diminish patient distress in intensive care settings and subsequent care phases. Discomfort may stem from pathophysiological influences (e.g., chronic diseases, therapeutic procedures, adverse events, and insufficient analgesia), mental health influences (including traumatic stress reactions, generalized worry states, panic episodes, and cognitive disruption), and environmental influences (e.g., social disconnection, accident specifics, and existential reflections)[4].

As outlined by Devlin et al[5], opioid-based therapeutic strategies continue to serve as foundational practice in pain control across the majority of critical care environments. Key clinical concerns regarding these therapies involve adverse reactions, which pose substantial safety risks including somnolence, neurological confusion, respiratory compromise, bowel obstruction, and immune system suppression – phenomena that may extend hospitalization duration in critical care suites and negatively impact post-discharge health trajectories.

Research conducted by Sandvik et al[6] identified multiple nonmedication treatments utilized within critical care facilities. These methodologies include hypnotic therapy, therapeutic bodywork, sensory diversion, tension-reduction strategies, pastoral care, lyre performance, rhythmic auditory interventions, exposure to ecosystem audio, physiotherapeutic mobilization, cryotherapy, and interpersonal emotional assistance. Of these therapeutic measures, hypnotic therapy, acupuncture, and exposure to environment audio have demonstrated efficacy in decreasing discomfort severity.

As documented by Puntillo et al[7], evaluating discomfort in patients who are critically ill presents a challenge due to the absence of universal assessment protocols. In responsive patients, personal symptom declarations-mainly using the Visual Analog Scale-remain the most trusted evaluation approach. For nonresponsive patients, only two evidence-based measurement tools have been validated for dependability, diagnostic accuracy, and practicality within intensive care environments: The Behavioral Pain Scale and the critical-care pain observation tool (CPOT).

Severgnini et al[8] noted that in nonresponsive patients, behavioral assessment tools such as the Behavioral Pain Scale and the CPOT are employed. The CPOT may demonstrate greater sensitivity due to its emphasis on muscular rigidity.

Pasero et al[9] argued that three elements hinder effective pain management in patients in the intensive care unit (ICU): The patient, healthcare team, and healthcare system. Furthermore, inadequate identification and evaluation, personal and cultural prejudices, and challenges in communication can be regarded as obstacles to pain management in the ICU.

Several studies have addressed pain in patients who are critically ill in the ICU from different perspectives. However, there is a lack of research highlighting the techniques and devices used by physiotherapy for pain management in this population. Therefore, this study explored some key physiotherapy approaches for pain control in these patients.

The search was performed across multiple electronic databases including PubMed/MEDLINE, and Cochrane Library, from January 2015 to February 2025. The following search terms were used in various combinations: "Physiotherapy", "physical therapy", "rehabilitation", "pain management", "pain control", "intensive care", "critical care", "critically ill", "early mobilization", "positioning", "manual therapy", "thermotherapy", "transcutaneous electrical nerve stimulation", and "photobiomodulation".

For this minireview, we included English and Portuguese language publications focusing on adult critically ill patients. We prioritized higher-quality evidence including randomized controlled trials (RCTs), systematic reviews, and clinical practice guidelines when available, supplemented by observational studies and narrative reviews where experimental evidence was limited. Studies were selected based on their relevance to physiotherapy interventions for pain management in ICU settings and the quality of their methodology. The review focused on six key physiotherapy interventions with potential applications in critical care: Early mobilization, positioning and postural management, manual therapy techniques, thermotherapy, transcutaneous electrical nerve stimulation (TENS), and photobiomodulation (PBM). For each intervention, we evaluated the available evidence regarding mechanisms of action, practical implementation, and reported effectiveness for pain control in critically ill patients.

Evidence categorization

Based on the quality and quantity of supporting evidence, each intervention was categorized as having: Strong evidence, defined as consistent findings from multiple high-quality RCTs; moderate evidence, defined as consistent findings from at least one high-quality RCT or multiple lower-quality trials; limited evidence, defined as single RCT or consistent findings from observational studies; conflicting evidence, defined as Inconsistent findings across studies; or insufficient evidence, defined as case series, expert opinion, or theoretical support only.

PHYSIOTHERAPY MODALITIES FOR PAIN CONTROL

Early mobilization

Early mobilization is a well-established practice in ICUs. It is used to prevent complications arising from prolonged immobility, such as muscle atrophy, weakness, respiratory dysfunction, and other issues that may indirectly intensify the sensation of pain[10,11]. However, when discussing its specific effect on pain relief, the current literature does not yet clearly establish the direct benefits of this approach in terms of function and overall patient recovery[12,13]. Early mobilization is achieved through a passive range of motion exercises, active-assisted exercises, bedside sitting and sitting in a chair, and progressive ambulation tailored to the patient’s condition and tolerance. Although the primary focus of early mobilization is to restore physical function and prevent complications, some mechanisms may indirectly contribute to pain management, such as the following: (1) Improved blood flow: Mobilization stimulates circulation, helping to reduce pain-associated inflammatory processes; (2) Reduction of stiffness and muscle spasms: Mobility and stretching exercises help decrease muscle stiffness, alleviating pain caused by immobility and prolonged postures; and (3) Endorphin release: Physical activity promotes the release of endorphins, which are naturally occurring neurotransmitters with analgesic properties that aid in pain relief.

Positioning and postural management

Immobility can lead to the development of pressure ulcers, affecting up to 45.5% of patients in ICUs[14]. Negative factors include discomfort, pain, increased risk of infections, prolonged hospitalization, higher healthcare costs, and increased mortality rates[15].

Appropriate positioning protocols and systematic repositioning represent fundamental, readily implementable interventions that effectively mitigate pain, redistribute pressure from bony prominences, and enhance patient comfort in intensive care settings[16]. These practices warrant prioritization for critically ill patients who frequently experience mobility limitations, as prolonged immobility substantially increases pressure injury risk.

Implementation requires comprehensive multidisciplinary engagement, with healthcare teams adhering to evidence-based repositioning schedules while applying biomechanical principles. This systematic approach facilitates effective pressure redistribution from vulnerable anatomical structures while minimizing tissue exposure to harmful mechanical forces, including direct pressure, shear stress, and frictional trauma[17]. The supporting surface should also be structured to prevent the body from returning to its initial position[18]. To achieve this, using pillows, wedges, and specific cushions tailored to the needs of each patient, is essential.

Manual therapy techniques

Manual therapy techniques play an essential role in treating pain resulting from actual or potential damage to nonneural tissue, with activation of nociceptors present throughout the body (nociceptive pain), as well as pain associated with injuries and/or diseases of the central or peripheral nervous system (neuropathic pain)[19].

Based on assessment findings-whether neural, muscular, or joint symptoms-the approach follows a hierarchy of tissues and aims to improve blood circulation, thereby enhancing the function of the affected tissue. No single pain therapy alone provides consistently significant benefits. In general, pain management requires a multimodal treatment approach to maximize the likelihood of effectiveness[20].

Neural mobilization, a manual therapy technique used for managing nociceptive and neuropathic pain, involves controlled and rhythmic movements of the selected nerve at the proximal, medial, or distal levels of its root, aiming to improve nerve conduction and intrinsic mobility (nerve movement between tissues).

The physiological mechanisms of neural mobilization encompass several key processes. This technique enhances neural mobility by releasing adhesions between neural tissues and adjacent structures, thereby alleviating mechanical compression of affected nerves. Consequently, pressure on nociceptors diminishes, reducing mechanical nociception. Additionally, improved regional blood flow and axoplasmic transport optimize tissue nutrition and metabolite clearance, potentially attenuating chemical nociceptive sensitivity. Neural mobilization modulates pain through neurophysiological mechanisms, specifically by increasing neural conduction via preferential stimulation of large-caliber afferent fibers (predominantly Aβ fibers). This selective activation creates competitive inhibition against nociceptive C-fiber transmission, effectively modulating pain signal propagation through established gate control mechanisms[21,22].

Another mechanism by which manual therapy may contribute to pain control is progressive muscle relaxation, reducing tension in muscle groups that can increase local nerve compression[23]. However, despite its widespread use in clinical practice, further studies are needed to confirm the therapeutic efficacy of manual therapy in pain management.

Thermotherapy

Thermotherapy consists of the application or removal of body heat for therapeutic purposes. Its effects include vasodilation, increased blood flow and oxygenation, elimination of metabolic waste, reduced nerve conduction of pain, decreased joint stiffness, and muscle relaxation[24].

Cryotherapy and thermotherapy are therapeutic modalities that contribute to pain relief with a low side effect profile. Although both modalities reduce pain and muscle spasms, they have opposite effects on tissue metabolism, blood flow, inflammation, edema, and connective tissue extensibility. Cryotherapy decreases these effects, while thermotherapy does the opposite[25]. Both modalities provide significant pain relief with minimal side effects[26].

Superficial heat is widely used and can be applied through hot water bags, electric heating pads, moist compresses, and other techniques, often preceding exercise and manipulation techniques[27]. There is no consensus on the best method, frequency, or duration of application, making the professional’s expertise the most crucial factor in determining the appropriate approach for optimal results[28].

TENS

TENS may be recommended for a subset of patients with localized pain as part of a multidisciplinary treatment, constantly adjusting the patient's expectations regarding outcomes[29,30]. TENS is a nonpharmacological intervention that applies low-frequency electrical current on the skin, promoting analgesia[30,31].

Meta-analysis data indicate that TENS can reduce pain intensity at rest (weighted mean difference: -1.83 points on a 0-10 scale; 95%CI: -2.35 to -1.31; P < 0.001; 8 RCTs, n = 427) and during movement (weighted mean difference: -1.97; 95%CI: -2.56 to -1.38; P < 0.001)[32]. Additionally, TENS has been shown to decrease primary hyperalgesia (pressure pain threshold improvement: 21.32%, P = 0.03), secondary hyperalgesia (affected area reduction: 45.7% ± 12.3%, P < 0.001), and inflammation (IL-6 reduction: 37%, P = 0.02)[32]. The technique helps restore central sensitization, improving function (standardized mean difference: 0.62; 95%CI: 0.41-0.83) and quality of life (SF-36 physical component improvement: 9.1 points; P = 0.007), with no significant adverse effects reported (risk ratio: 1.05; 95%CI: 0.91-1.21)[32,33].

The mechanism of action involves the possibility of working at high frequency in the conventional form, producing depolarization of Aβ fibers and inhibiting nociceptive transmission to the spinal cord. It can also work at low frequency, known as the "breakthrough mode", where Aδ fibers are depolarized, activating descending analgesia. Both actions activate opioid receptors in the central nervous system, including serotonin and Mµ or delta-type opioid receptors[34].

The mechanism-to-outcome relationship in critical care depends significantly on parameter selection. High-frequency TENS (80-120 Hz) with lower intensity produces rapid but shorter-duration analgesia through spinal gate mechanisms and is particularly effective for procedural pain in communicative ICU patients. Conversely, low-frequency TENS (2-10 Hz) with higher intensity activates endogenous opioid pathways, providing slower onset but longer-lasting analgesia that may be more suitable for background pain management. In critically ill patients, evidence suggests that alternating frequencies (2 Hz/100 Hz) may provide optimal analgesia by activating both pathways simultaneously while minimizing accommodation effects.

Clinical translation studies demonstrate that TENS efficacy varies by pain etiology in ICU settings. For post-surgical incisional pain, electrode placement 2-3 cm from the incision using high-frequency parameters (100 Hz, 100-150 μs pulse width) for 20-30 minutes reduces pain scores by 30%-45% while decreasing opioid consumption by 20%-25%[35]. For musculoskeletal pain associated with critical illness polyneuropathy, low-frequency TENS (4-10 Hz, 200-300 μs) applied directly to painful muscle groups has demonstrated comparable efficacy to low-dose gabapentinoids without associated delirium risk in small controlled trials[36].

TENS has various clinical applications and may be indicated to relieve different types of pain, such as acute and chronic pain, musculoskeletal and neuropathic pain, and postoperative pain[29,30,32]. It reduces peripheral and central sensitization, promotes adequate analgesia, reduces pain at rest and during movement, improves functionality, decreases medication consumption, and reduces associated adverse events[37]. Its physiological effects on the neuromusculoskeletal system include analgesia, reduced edema and reflex inhibition, and facilitation of soft tissue injury healing.

Practical TENS protocol for critical care

For post-thoracotomy/sternotomy pain: (1) Frequency: 100 Hz alternating with 4 Hz every 3 seconds; (2) Pulse duration: 200 μs; (3) Intensity: Sensory threshold (patient feedback) or when muscle fasciculation is observed in sedated patients; (4) Electrode placement: Parallel to incision, 2-3 cm distance bilaterally; (5) Treatment duration: 30-45 minutes, 2-4 times daily; (6) Progression: Increase intensity by 10% when tolerated; (7) Monitoring parameters: Pain scores, analgesic consumption, respiratory parameters; and (8) Contraindications: Pacemakers, implanted defibrillators, open wounds at electrode sites.

Clinical case application: Several well-designed clinical studies have demonstrated the effectiveness of TENS in critically ill patients. A RCT evaluating TENS in post-surgical ICU patients (n = 68) found significant pain reduction from baseline (mean: 6.9 ± 1.5) to post-intervention (3.5 ± 1.1) on a 0-10 numerical rating scale (mean difference: 3.4 points; 95%CI: 2.6-4.2; P < 0.001)[38].

A TENS intervention group also experienced a 31% reduction in opioid consumption compared to standard care (morphine equivalent daily dose decreased from 36.4 ± 7.2 mg to 25.1 ± 5.7 mg, P = 0.003)[39].

Application protocols vary across studies, with optimal parameters including frequencies of 80-120 Hz for acute pain, pulse durations of 50-200 μs, and treatment durations of 20-30 minutes applied 3-4 times daily. These parameters have been shown to activate endogenous opioid systems and modulate pain transmission through the gate control mechanism[40].

All electrostimulation strategies should be combined with frequency variations, intensity increase, and association with exercises, as they seem more effective in improving analgesia and optimizing therapeutic benefits.

PBM

Pain is a frequent issue among patients who are critically ill in the ICU, arising from various causes. Effective pain management is crucial to enhance recovery and minimize related complications. In this regard, PBM has been widely researched as a nondrug alternative. It provides an affordable, noninvasive therapy with minimal adverse effects, setting it apart from conventional pharmacological methods[41].

The efficacy of light therapy depends on wavelength, intensity, and delivery method. Red light (625–740 nm) and infrared light (750–1000 nm) exhibit deep tissue penetration, necessitating only brief or short-term application durations to trigger PBM. These wavelengths interact with cellular structures such as cytochrome c oxidase, thereby stimulating ATP production, increasing intracellular calcium levels, enhancing mitochondrial membrane permeability, and promoting vasodilation, ultimately facilitating a regenerative state in the cells[42].

Wavelength-specific effects in critical care

The clinical translation of PBM mechanisms depends critically on wavelength selection and tissue penetration properties. In critically ill patients with different tissue damage profiles, wavelength selection determines therapeutic efficacy.

Red wavelengths (630-660 nm): These wavelengths penetrate 1-2 mm into tissue, making them suitable for superficial applications in the ICU setting. Clinical applications include pressure injury prevention and treatment (stages I-II), oral mucositis in ventilated patients, and superficial wound healing in critically ill patients. The primary cellular target is cytochrome c oxidase in mitochondria, with increased ATP production and nitric oxide release occurring within 20 minutes of application[43].

Near-infrared wavelengths (810-850 nm): These wavelengths penetrate 2-4 cm into tissue, allowing targeting of deeper structures including muscle and neural tissue. In critical care, these wavelengths are particularly effective for managing myofascial pain associated with immobility, neuropathic pain from critical illness polyneuropathy, and possibly modulating inflammatory responses in deep tissues. The mechanism transitions from primarily mitochondrial effects to include modulation of calcium channels and inflammatory mediators. Clinical outcomes correlate with dosage; low doses (5-10 J/cm²) produce predominantly anti-inflammatory effects, while higher doses (30-50 J/cm²) enhance tissue repair processes[44].

Longer near-infrared wavelengths (900-1070 nm): These wavelengths achieve the deepest penetration (up to 5-7 cm) and have shown particular promise for neuroprotective applications in neurological critical care. The primary mechanisms involve transcranial effects on cerebral blood flow and neuronal metabolism[45].

Preclinical and clinical studies

PBM was shown to modulate pain by influencing signaling in the peripheral nervous system, which translates into central pain modulation[46]. A methodologically rigorous randomized, double-blind, placebo-controlled clinical trial (n = 57) evaluating PBM therapy for chronic cervical pain demonstrated statistically significant and clinically sustained analgesic effects following the application of precisely calibrated near-infrared light (830 nm wavelength, 300 mW power output, 9 J/point dosage, 20 J/cm² energy density). The intervention protocol yielded a mean pain reduction of 3.7 points (95%CI: 2.9-4.5) on a 10-point visual analog scale compared to 1.2 points (95%CI: 0.7-1.7) in the placebo group (P < 0.001, effect size = 1.85). This significant effect was maintained at 3-month follow-up assessment (between-group difference: 2.1 points, P = 0.003). No adverse events were documented, supporting its consideration as a safe therapeutic modality in appropriate clinical contexts[47].

In addition to musculoskeletal pain, PBM demonstrated neuroprotective properties. Research indicates that this treatment enhances cerebral circulation, neuronal metabolic activity, neuroinflammatory responses, oxidative stress levels, neurogenesis, and the release of neurotrophic factors, thereby supporting the stability of neural pathways[48]. Additionally, PBM is thought to affect hormone production, elevating the discharge of serotonin and endorphins, which aids in lowering pain perception[49].

Dosage protocols and clinical application

Practical PBM protocol for critical care applications: For neuropathic pain in critically ill patients: (1) Wavelength: 830 nm (Class 3B laser or LED array); (2) Power density: 100-150 mW/cm²; (3) Energy density: 30-40 J/cm²; (4) Treatment area: Pain distribution plus proximal nerve pathway; (5) Application: Grid technique with 2 cm spacing between points; (6) Duration/frequency: 30-60 seconds per point, daily for acute conditions; (7) Total treatment time: 10-15 minutes per session; and (8) Expected outcomes: 30%-45% reduction in neuropathic pain scores, measurable within 3-4 treatments. For pressure injury prevention in high-risk ICU patients: (1) Wavelength: 660 nm (red) for superficial prevention, 850 nm for established injuries; (2) Energy density: 5-10 J/cm² for prevention, 20-30 J/cm² for treatment; (3) Application pattern: 5-point pattern centered on high-risk area plus 1 cm border; (4) Treatment frequency: Every 48 hours for prevention, daily for established injuries; and (5) Implementation strategy: Integration with regular repositioning protocol.

Real-world implementation: A quality improvement project in a 24-bed medical ICU incorporated PBM into standard pressure injury prevention protocols for high-risk patients (Braden score < 12). Implementation reduced pressure injury incidence by 62% compared to historical controls and demonstrated cost savings for healthcare systems[50].

Implementation challenges in ICU settings

Despite the potential benefits of physiotherapy interventions for pain management in critically ill patients, several practical barriers limit widespread implementation. These challenges vary by intervention type and ICU setting.

Patient-related barriers

Critical illness presents unique obstacles to physiotherapy implementation. Hemodynamic instability affects approximately 30%-40% of ICU patients at any given time, limiting candidacy for interventions like early mobilization and certain manual therapy techniques. Altered consciousness (affecting up to 70% of ICU patients) impacts patient cooperation and pain assessment reliability, complicating intervention selection and efficacy evaluation. Additionally, the presence of multiple medical devices (ventilators, catheters, monitoring equipment) creates physical barriers to optimal positioning and intervention delivery.

Resource and organizational constraints

Specialized staffing requirements represent a significant implementation barrier. While positioning can be performed by bedside nurses, interventions like manual therapy and advanced mobilization often require dedicated physical therapists, who are frequently a limited resource in ICU settings. Studies report median physical therapist-to-ICU patient ratios ranging from 1:8 to 1:12, with substantial geographic variation. Time constraints further complicate implementation, with surveys indicating competing priorities often lead to abbreviated or postponed physiotherapy sessions. Equipment availability (particularly for specialized interventions like PBM) varies dramatically across institutions and healthcare systems.

Interdisciplinary coordination challenges

Optimal implementation requires coordination across multiple disciplines (nursing, medicine, respiratory therapy, physiotherapy), creating logistical challenges in workflow integration. Documentation inconsistencies, communication barriers, and varying prioritization across disciplines can impede systematic implementation. Studies examining implementation success factors consistently identify interdisciplinary protocols and clear responsibility allocation as critical elements.

Intervention-specific implementation considerations

Early mobilization: Despite strong theoretical benefits, early mobilization faces substantial practical barriers in typical ICU settings. Patient factors represent the primary limitation-studies report that 40%-60% of ICU patients have contraindications including hemodynamic instability (mean arterial pressure < 60 mmHg or requiring high-dose vasopressors), respiratory instability (FiO₂ > 0.6, positive end-expiratory pressure > 10 cmH₂O), or neurological concerns (intracranial pressure > 20 mmHg). Staffing requirements constitute another significant barrier, with safe mobilization of critically ill patients typically requiring 2-4 personnel simultaneously, a resource not consistently available in many ICUs. Implementation studies report that despite protocols, only 45%-60% of eligible patients receive the prescribed mobilization, primarily due to staffing constraints and competing clinical priorities[51]. These practical limitations must be considered when evaluating the role of early mobilization in comprehensive ICU pain management.

Positioning: While positioning represents one of the most accessible interventions, implementation challenges remain. In practice, optimal positioning for pain management may conflict with other clinical priorities such as ventilation optimization, pressure injury prevention, or procedural access. Additionally, patient factors including body habitus, presence of trauma or surgical sites, and medical devices (particularly multiple drains or extracorporeal membrane oxygenation cannulation) can significantly limit positioning options. Unstable spinal injuries, which occur in 5%-8% of multi-trauma ICU patients, present absolute contraindications to certain positions. Implementation studies reveal significant variation in adherence to positioning protocols[52].

Manual therapy: Manual therapy implementation in ICU settings is constrained by several factors. The specialized training required for effective and safe application means availability is typically limited to facilities with dedicated rehabilitation specialists. Patient selection represents another significant barrier, as manual techniques are often contraindicated in patients with coagulopathies (affecting approximately 25%-35% of critically ill patients), recent surgical incisions, or hemodynamic sensitivity to positional changes. Additionally, the time required for proper assessment and treatment (typically 20-30 minutes per session) may compete with other critical care priorities in resource-limited environments. Documentation of manual techniques is often inconsistent, limiting systematic evaluation of outcomes.

Thermotherapy: Thermotherapy application in ICU settings presents unique challenges. For cryotherapy, maintaining appropriate temperature for therapeutic duration can be difficult, with studies showing warming of cold packs to nontherapeutic temperatures within 10-15 minutes in some hospital environments. For heat therapy, maintaining skin integrity monitoring is essential yet challenging in sedated patients or those with sensory impairments. The proximity of monitoring equipment creates practical application barriers and potential interference with electrode adhesion. Additionally, thermotherapy application timing must be coordinated with other care activities, requiring interdisciplinary communication that is often challenging in busy ICU environments.

TENS: TENS implementation faces both technical and practical barriers in ICU settings. Equipment-related challenges include potential interference with monitoring devices (reported in up to 18% of applications), limited electrode placement options due to competing medical devices or surgical sites, and difficulties maintaining proper electrode contact with patient movement or diaphoresis. Staff training represents another barrier-proper electrode placement and device adjustment require specific training not routinely provided to ICU staff. Additionally, TENS efficacy assessment requires patient feedback, limiting utility in sedated or non-communicative patients who comprise a substantial proportion of the ICU population.

PBM: PBM represents the most resource-intensive intervention with significant implementation barriers. Equipment costs and limited availability restrict use primarily to specialized centers or research settings. The required technical expertise for proper dose delivery, wavelength selection, and treatment targeting necessitates specialized training rarely available among standard ICU staff. Treatment duration and frequency (typically requiring 10- to 20-minute sessions several times weekly) create scheduling challenges within routine ICU workflows. Furthermore, the limited ICU-specific evidence base results in uncertainty regarding optimal parameters for critically ill patients, limiting protocol standardization.

PRACTICAL IMPLEMENTATION STRATEGIES

Several approaches can mitigate the identified barriers to physiotherapy implementation.

Protocol-based implementation

Structured protocols with clear eligibility criteria, contraindications, and implementation steps improve consistent delivery. Successful examples include the ABCDEF bundle, which integrates early mobility with other ICU care elements.

Resource optimization

Given universal resource constraints, strategic approaches include: (1) Prioritization algorithms that identify patients most likely to benefit; (2) Integration of basic physiotherapy interventions into nursing workflows; (3) "Therapy champions" on each shift to facilitate proper technique; and (4) Use of available technology (e.g., ceiling lifts) to reduce personnel requirements.

Interdisciplinary approaches

Successful integration requires: (1) Collaborative protocol development with input from all disciplines; (2) Shared documentation systems; (3) Regular interdisciplinary rounds that include physiotherapy; and (4) Education across disciplines regarding intervention benefits and techniques.

CONCLUSION

Pain management for critically ill patients remains a multifaceted clinical challenge requiring integrated approaches that extend beyond traditional pharmacotherapy. While opioid-based regimens continue to serve as foundational treatment, their well-documented adverse effects-including respiratory depression, delirium, and immunosuppression-necessitate complementary strategies to optimize analgesia while minimizing complications. Physiotherapy interventions have emerged as essential components within this framework, addressing the complex interplay of physiological, psychological, and environmental factors that contribute to pain experiences in ICU settings.

The integration of these physiotherapeutic approaches into standardized ICU protocols offers multiple advantages, including complementary mechanisms of pain modulation, reduced pharmacological burden, treatment of underlying physical dysfunction, and enhanced patient autonomy during critical illness. Despite these promising outcomes, however, significant challenges persist in optimizing physiotherapy-based pain management in critical care. The heterogeneity of critically ill populations necessitates personalized intervention protocols, yet standardized assessment tools and treatment algorithms remain underdeveloped. Additionally, questions regarding optimal timing, dosage parameters, and progression criteria require further investigation to maximize clinical effectiveness.

Future research priorities should focus on three key areas, namely developing validated decision-support frameworks for selecting patient-specific physiotherapy interventions, conducting adequately powered randomized trials comparing different modalities and combination approaches, and investigating the longitudinal impact of early physiotherapy interventions on post-ICU pain trajectories and functional recovery. Such evidence would address critical knowledge gaps and strengthen implementation guidelines.

Ultimately, physiotherapeutic approaches represent essential components within comprehensive pain management strategies for critically ill patients. A coordinated, interprofessional approach that systematically integrates evidence-based physiotherapy interventions with pharmacological management has significant potential to enhance patient comfort, accelerate recovery, and improve clinical outcomes in intensive care settings. By embracing this integrated paradigm, critical care teams can advance toward more holistic, effective pain management practices that acknowledge the multidimensional nature of pain in critical illness (Table 1).

Table 1 Non-pharmacological interventions for pain management.

Intervention	Level of evidence	Key findings	Pain reduction	Main barriers
Early mobilization	Moderate	Helps prevent complications associated with immobility and offers indirect pain relief	Not quantified	40%–60% of patients may have contraindications; typically requires 2-4 staff for implementation
Positioning	Strong	Fundamental for pain management and significantly reduces pressure injuries (up to 45.5%)	Not quantified	May conflict with other clinical priorities; limitations due to medical devices
Manual therapy	Limited	Effective for both nociceptive and neuropathic pain	Not quantified	Requires specialist availability; contraindicated in 25%–35% of patients
Thermotherapy	Moderate	Provides significant analgesia with minimal adverse effects	Not quantified	Challenges include maintaining proper temperature and monitoring patients
TENS	Strong	Demonstrates the most robust, quantified outcomes, with pain scores reduced by 1.8–2.0 points and a 31% reduction in opioid use	Pain score reduced from 6.9 to 3.5 (0–10 scale)	Potential interference with equipment (18% of cases); requires patient feedback for optimal use
PBM	Limited–moderate	Produces sustained pain relief and leads to a 62% reduction in pressure injuries	Pain reduction of 3.7 vs 1.2 points compared to placebo	Most costly intervention; requires personnel with specialized training

TENS: Transcutaneous electrical nerve stimulation; PBM: Photobiomodulation.

ACKNOWLEDGEMENTS

We want to express our sincere gratitude to Hospital Israelita Albert Einstein for their unwavering support in conducting this research. The resources, facilities, and collaborative environment provided by the institution were instrumental in facilitating our study.