Nursing interventions in intensive care unit patients with breathing difficulties: A scoping review of the evidence

Abstract

For patients in intensive care units, long periods of bed rest and restricted physical activity can result in adverse side effects. One of the conditions many patients experience during intensive care unit stays is breathing difficulty. Here, we aimed to identify and evaluate the evidence base for nonpharmacological or nontechnical interventions targeting breathing difficulties, and to propose interventions needing further investigations. This study is reported in accordance with PRISMA for Scoping Reviews. A systematic search was conducted in MEDLINE, EMBASE, and Cochrane. A scoping review was undertaken using the Arksey and O’Malley framework. In all, 1190 records were found and 27 of them were included in the review. Interventions targeting breathing difficulties were chest physiotherapy, breathing techniques, inspiratory muscle training, early exercise training, position-specific optimization, and other nonpharmacological interventions. Several of the interventions showed minor beneficial effects. However, because of limitations in the studies, the findings are inconclusive and need further research.

Keywords

critically ill patients nursing respiration scoping review

Background

Intensive care unit (ICU) patients, by definition, are critically ill. Most are mechanically ventilated, and require sedative and analgesic drugs to reduce distress, pain, and oxygen consumption during their stay. Long periods at the ICU with restricted physical activity and enforced bed rest can result in numerous alterations in body function, such as neuromuscular weakness, pressure ulcers, atelectasis, aspiration pneumonia, muscle weakness and atrophy, bone mineral loss, orthostatic hypotension, tachycardia, and decreased cardiac output.^1–4 These ICU-acquired conditions can lead to significant impairment of function after the patients leave the unit. Many of the survivors develop new or worsening physical, cognitive, and/or mental impairments after ICU treatment,^5–8 which now is recognized as post-intensive care syndrome (PICS).⁹ This aspect is often ignored, which can lead to a reduced quality of life and increased suffering for these patients after ICU discharge.

One set of conditions many patients experience during ICU stay comprises breathing difficulties. For example, ICU patients are at high risk of dyspnea,¹⁰,¹¹ and this is a major cause of emotional distress and physical suffering for them. In one study, 171 ICU patients at high risk of dying were interviewed every other day for up to 14 days. Dyspnea was prevalent in 44% of the assessments and was the most distressing symptom. In this study, no differences were found in dyspnea intensity or distress ratings reported by patients who were mechanically ventilated versus those who were not.¹² It is worth noting that even if increased attention is being given to this symptom,¹³ ICU clinicians often underestimate breathing discomfort in these patients.¹⁴,¹⁵ In addition, other breathing difficulties are present in patients with serious illness, including cough, malignant pleural effusions, airway secretions and hemoptysis. Beyond physical effects, these symptoms exert significant psychological, social, existential, and spiritual impact on the patients’ experience.¹⁶

Nurses working with ICU patients often have an important role in assessing and treating distressing symptoms as they are beside these patients during their whole ICU stay. For example, in a country like Norway, critical care nurses, who have a minimum of 1.5 years of further education after receiving a bachelor’s degree in nursing, play an important role regarding ICU patients’ breathing difficulties. Nurses mobilize and reposition these patients several times per day. Other procedures include secretion removal, oral care, oxygen therapy, and respiratory monitoring.¹⁷ Often, these nursing interventions are nonpharmacological or nontechnical, and the effects of these interventions are not always clear. To be able to motivate patients to do these interventions, and to know that our work is based on best evidence, it is important to have an overview of which of these interventions are effective. For these reasons, a scoping review was conducted in order to systematically map the research done in this area, as well as to identify any existing gaps in knowledge. The aim of this study was therefore to provide an overview of the literature regarding such nursing interventions for ICU patients with breathing difficulties. We had two specific aims: first to identify and evaluate the evidence base for nonpharmacological or nontechnical interventions targeting breathing difficulties in ICU patients; and second, to propose similar interventions that need further investigation.

Methods

This study is reported in accordance with PRISMA for Scoping Reviews.¹⁸ The present scoping review, was defined as a ‘form of knowledge synthesis that addresses an exploratory research question aimed at mapping key concepts, types of evidence, and gaps in research related to a defined area or field by systematically searching, selecting and synthesizing existing knowledge’.¹⁹^(p.1292) To study the knowledge base for nursing activities and identify research gaps, we applied the framework suggested by Arksey and O’Malley.²⁰ This includes a five-step approach: 1) identification of the research question; 2) identification of relevant studies; 3) study selection; 4) charting the data; and 5) collating, summarizing, and reporting the results.

Literature search

To identify potentially relevant documents, a systematic literature search was performed in cooperation with a health science librarian with expertise in systematic review searching. Medical subject headings and text words related to patients with breathing difficulties, ICU patients, and nonpharmacological and nontechnical nursing interventions were used. The search was conducted without any date limitations, and the keywords were broad to ensure we captured the current evidence. The search was conducted on July 9, 2018 and we searched MEDLINE, EMBASE, as well as the Cochrane Central Register of Controlled Trials. For further details, see Table 1.

Table 1.

Complete search strategy.

#	Searches in Embase 1974 to 6 July 2018, and in Ovid MEDLINE(R) Epub ahead of print, in-process & other nonindexed citations, Ovid MEDLINE(R) Daily, Ovid MEDLINE and Versions(R) 1946 to 5 July 2018	Results
1	Dyspnea/	160103
2	dyspn*.tw.	113120
3	breathless*.tw.	11853
4	(breath* adj3 (difficult* or labour* or shortness)).tw.	26682
5	((ventilat* or oxygen* or desaturat* or hypoxemi) adj3 patient).tw.	69645
6	or/1-5	292876
7	(non adj (medicin* or pharma* or technical*)).tw.	25039
8	(physical therap* or physiotherap*).tw.	105301
9	(reposition* or mobilizat* or exercis* or ((upright or side-lying) adj position*)).tw.	748092
10	(massage* or hypnosis or acupuncture or homeopath* or (music adj1 therap) or (psych adj1 support) or spiritual care or cold application or ice pack or (oil adj1 inhal) or breathing exercise*).tw.	121281
11	or/7-10	963345
12	6 and 11	23429
13	(((critical or intensive) adj2 care) and patient*).tw.	253991
14	12 and 13	899
#	Searches in Cochrane Central Register and Controlled Trials (CENTRAL)	Results
1	(dyspn* or breathless* or (breath* near (difficult* or labour* or shortness)) or ((ventilat* or oxygen* or desaturat* or hypoxemi) near patient)):ti,ab,kw	20430
2	(non medicin* or non pharma* or non technical* or physical therap* or physiotherap* or reposition* or mobilizat* or exercis* or upright position* or side-lying position*):ti,ab,kw	120788
3	(massage* or hypnosis or acupuncture or homeopath* or (music adj1 therap) or (psych adj1 support) or spiritual care or cold application or ice pack or (oil adj1 inhal) or breathing exercise*):ti,ab,kw	20136
4	#2 or #3	135627
5	(((critical or intensive) near care) and patient*):ti,ab,kw	15412
6	#1 and #4 and #5 in Trials	291

Inclusion and exclusion criteria

Three critical care nurses (the reviewers in this study) discussed inclusion and exclusion criteria for publications. To be included in the review, the following inclusion criteria were applied: patients were enrolled in an ICU (including both mechanically ventilated ICU patients and nonmechanically ventilated ICU patients), and aged 18 years or older; breathing difficulties were recorded as main or secondary outcomes; they needed to be original studies (i.e. no author opinions, case studies, or systematic reviews); and only English-language studies. Studies were excluded if they included pharmacological (i.e. medications) or technical (i.e. noninvasive ventilation [NIV] or mechanical ventilation) interventions. Protocols not leading to any publication were excluded, as were conference abstracts and unpublished data.

Study selection

After removing duplicates, conference abstracts, and records not in English, groups of two reviewers independently evaluated titles and abstracts from the records identified through database searching, followed by a discussion and final consensus about which studies to include as full-text articles. Thereafter, included full-text articles were read (also here in groups of two reviewers). Before final selection of the full-text articles to be included, the reviewers discussed any conflicting decisions, so that any disagreement was resolved by discussion and consensus before final study selection.

Data extraction

Because this is a scoping review, we used data extraction and not quality appraisal.²⁰ A data-charting form was developed to determine which variables to extract. Groups of two reviewers read the included studies individually and extracted the following key information: author(s); year of publication; origin/country of origin (where the study was published or conducted); aims/purpose; study population and sample size; methodology; intervention type; comparators and details of these; duration of the intervention (if applicable); outcomes and details of these (if applicable); and key findings related to the scoping review question. Disagreements were resolved in a discussion between the three reviewers extracting the data.

Analysis

We grouped the studies thematically by the type of intervention used, resulting in six categories: chest physiotherapy; breathing techniques; early exercise training; inspiratory muscle training; position-specific optimization; and nonpharmacological interventions. The results were presented in a narrative format, in a flow diagram (Figure 1), and in tables (Table 2 and Table 3).

Figure 1.

Identification and inclusion of studies.

Table 2.

Overview of the included studies according to country of origin, aim, study population, and design.

Author(s) and year	Country	Aim	Study population	Design
Chest physiotherapy
Barker and Adams (2002)²⁶	UK	To evaluate the effects of a single chest physiotherapy session on vital signs	MV (n = 18) Acute lung injury	RCT
Pattanshetty and Gaude (2010)²⁷	India	To evaluate the effect of multimodality chest physiotherapy on the prevalence of ventilator-associated pneumonia, duration of MV, and ICU length of stay	MV (n = 101)	RCT
Yousefnia-Darzi et al. (2016)²⁸	Iran	To investigate the short-term effect of thoracic compression on secretion removal	MV (n = 50)	RCT, crossover design
Bousarri et al. (2014)²⁵	Iran	To determine the effect of expiratory rib cage compression before endotracheal suctioning on vital signs	MV (n = 50)	RCT, crossover design
Naue et al. (2014)²⁹	Brazil	To determine the efficacy of chest compression accompanied by a 10-cm H₂O increase in baseline inspiratory pressure on pressure support ventilation, compared with aspiration alone, in removing secretions, normalizing hemodynamics, and improving respiratory mechanics	MV (n = 34)	RCT, crossover design
Berti et al. (2012)³⁰	Brazil	To evaluate the effect of manual hyperinflation combined with expiratory rib cage compression on the length of ICU stay and duration of MV	MV (n = 49)	RCT, prospective
Templeton and Palazzo (2007)³¹	UK	To determine the impact of providing chest physiotherapy after routine clinical assessment on duration of MV, length of ICU stay, and mortality	MV (n = 180)	RCT, prospective
Unoki et al. (2005)³²	Japan	To determine the effects of rib cage compression on airway-secretion aspiration, oxygenation, and ventilation	MV (n = 31)	RCT, crossover design
Guimaraes et al. (2014)³³	Brazil	To evaluate an expiratory rib cage compression protocol on acute mechanical effects and sputum clearance	MV (n = 20) Pulmonary infection	RCT, crossover design
Breathing techniques
Inal-Ince et al. (2004)²¹	Turkey	To evaluate the effects of an active cycle of breathing techniques on length of time requiring NIV, acute physiology score, change in arterial blood gas values, total duration of NIV, and ICU length of stay	NIV (n = 34) Acute hypercapnic respiratory failure	RCT
Westerdahl et al. (2005)²³	Sweden	To investigate the effects of deep-breathing exercises on pulmonary function, atelectasis, and arterial blood gas levels	After coronary artery bypass graft (n = 90)	RCT, prospective
Inspiratory muscle training
Bissett et al. (2016)³⁴	Australia	To evaluate the effects of inspiratory muscle training on inspiratory muscle strength and fatigue resistance index, and dyspnea, physical function, quality of life, post-ICU length of stay, and in-hospital mortality	MV (n = 70)	RCT, assessor-blinding
Caruso et al. ( (2005)³⁵	Brazil	To evaluate whether inspiratory muscle training from the beginning of MV would shorten the weaning duration and decrease the reintubation rate	MV (n = 25)	RCT, prospective
Early exercise training
Medrinal et al. (2018)³⁶	France	To compare the physiological effects of four common types of bed exercise	MV (n = 19)	RCT, crossover design, single-blind, placebo-controlled
Porta et al. (2005)²²	Italy	To evaluate the effects of early exercise training	Recently weaned from MV (n = 66)	RCT, prospective
Dong et al. (2014)³⁷	P. R. China	To investigate the feasibility and effects of early rehabilitation therapy	MV (n = 60)	RCT
Schweickert et al. (2009)²	USA	To assess the efficacy of combining daily interruption of sedation with physical and occupational therapy on functional outcomes	MV (n = 104)	RCT
Nava (1998)³⁸	Italy	To examine the effect of pulmonary rehabilitation on some physiologic variables	MV (n = 80) Chronic obstructive pulmonary disease	RCT, prospective
Dong et al. (2016)³⁹	P. R. China	To investigate the effects of early rehabilitation therapy	MV (n = 106) After coronary artery bypass surgery	RCT, prospective
Position-specific optimization
Gutierrez et al. (2010)⁴⁰	USA	To determine whether position-specific chest optimization is associated with changes in spontaneous breathing trial duration	MV (n = 12) Low spinal cord injury	RCT, crossover design, double-blinded
Chang et al. (2011)⁴¹	Taiwan	To evaluate the effect of chair-sitting during exercise training on respiratory muscle function	MV (n = 34)	RCT
Thomas et al. (2014)⁴²	Australia	To compare the effect of semi-recumbent and sitting positions in gas exchange, respiratory mechanics, and hemodynamics	MV (n = 34) Weaning from MV	RCT, prospective
Nonpharmacological interventions
Tsay et al. (2005)²⁴	Taiwan	To evaluate the effects of acupressure therapy on dyspnea, anxiety, and physiological indicators of heart rate and respiratory rate	MV (n = 52) Chronic obstructive pulmonary disease	A two-group experimental design with repeated measures
Akgul et al. (2016)⁴³	Turkey	To evaluate the beneficial effects of clinical hypnotherapy on perioperative anxiety, pain, perception, sedation, and necessity for ventilator assistance	MV (n = 44) Coronary artery bypass grafting	RCT, double-blind
Han et al. (2010)⁴⁴	P. R. China	To examine the effects of listening to music on the stress response and anxiety level	MV (n = 137)	RCT, placebo-controlled
Yaman Aktas and Karabulut (2015)⁴⁵	Turkey	To examine the effect of music therapy during endotracheal suctioning on pain intensity, sedation level, and physiological parameters	MV (n = 66) Cardiovascular surgery	RCT, single-blind experimental study
Yadak et al. (2019)⁴⁶	Saudi Arabia	To investigate the effect of listening to Holy Quran recitation on weaning from MV	MV (n = 55) Weaning from MV	RCT

Notes: ICU: intensive care unit; MV: mechanical ventilation; NIV: noninvasive ventilation; RCT: randomized controlled trial.

Table 3.

Presentation of the results.

Author(s) and year	Intervention (duration if applicable)	Respiratory outcomes	Key findings related to the scoping review question
Chest physiotherapy
Barker and Adams (2002)²⁶	Group 1: 30° supine position, preoxygenated, suctioned. Group 2: 30° supine position, preoxygenated, repositioned at left and right lateral decubitus, suctioned. Group 3: 30° supine position, preoxygenated, repositioned, manually hyperinflated, suctioned.	Laboratory results Vital signs Ventilator parameters	Protracted physiotherapy interventions might have a role in later or recovery stages of the acute lung injury. Physiotherapy should be modified individually for each patient.
Pattanshetty and Gaude (2010)²⁷	Positioning, chest wall percussion, manual hyperinflation, and aspiration vs manual hyperinflation, aspiration.	Clinical Pulmonary Infection Score Ventilator parameters Radiological features suggesting pneumonia	Twice-daily multimodality chest physiotherapy was associated with a significant decrease in the Clinical Pulmonary Infection Score in the intervention group, suggesting a decrease in the occurrence of VAP. There were also significant reductions in mortality rates and MV weaning.
Yousefnia-Darzi et al. (2016)²⁸	In each patient, two interventions of endotracheal aspiration, one with and the other without thoracic compression during exhalation.	Weight of the secretions Duration of MV Ventilator parameters	Endotracheal suction with thoracic compression on expiration helped airway secretion discharge more than suction alone in patients on MV. The forced expiratory volume increased by 30% during thoracic compression.
Bousarri et al. (2014)²⁵	Endotracheal aspiration with or without rib cage compression.	Vital signs Duration of MV	Expiratory rib cage compressions before endotracheal aspiration significantly increased the vital signs within the normal range in patients receiving MV.
Naue et al. (2014)²⁹	Chest compression, 10-cm H₂O increase in baseline inspiratory pressure on pressure support ventilation, and airway aspiration vs airway aspiration.	Weight of the secretions Vital signs Ventilator settings Lung function	Chest compression accompanied by an increase in pressure support significantly increased the amount of secretions removed, the expiratory tidal volume, and dynamic compliance.
Berti et al. (2012)³⁰	Manual hyperinflation, expiratory rib cage compression, vs standard nursing care.	Ventilator parameters Vital signs Pulmonary auscultation Lung function Chest X-ray Duration of MV	The use of manual hyperinflation combined with expiratory rib cage compression for five days accelerated the weaning process and ICU discharge.
Templeton and Palazzo (2007)³¹	Physiotherapy (as deemed appropriate by physiotherapists after routine daily assessments), vs decubitus care and tracheal aspiration.	Auscultation Chest X-ray CT reports Laboratory results Information from staff	Simple aspiration and decubitus positioning were at least as effective as chest physiotherapy in patients receiving MV.
Unoki et al. (2005)³²	Endotracheal aspiration with or without rib cage compression.	Laboratory results Ventilator parameters Weight of the secretions	Rib cage compression prior to endotracheal aspiration did not improve short-term airway-secretion removal, oxygenation, or ventilation after endotracheal aspiration in an unselected population of patients receiving MV.
Guimaraes et al. (2014)³³	Manual bilateral expiratory rib cage compression followed by a hyperinflation maneuver vs the same sequence, but instead of the compressive maneuver, the subjects were kept on normal ventilation.	Weight of the secretions Clinical Pulmonary Infection Score PaO₂/FiO₂ Ventilator parameters Duration of MV	Although expiratory rib cage compressions increased expiratory flow, they had no clinically relevant effects in improving the sputum production and respiratory mechanics in hypersecretive patients receiving MV.
Breathing techniques
Inal-Ince et al. (2004)²¹	NIV and active cycle of breathing once daily vs NIV alone.	Duration of NIV Laboratory results Ventilator parameters Vital signs	The use of active cycle of breathing might have positive effects in the treatment of patients with acute hypercapnic respiratory failure, resulting in a shorter time requiring NIV.
Westerdahl et al. (2005)²³	Breathing exercises hourly during daytime, physiotherapy and early mobilization vs physiotherapy and early mobilization.	Lung function Spiral CT Laboratory results Scoring of subjective experience	Patients performing deep-breathing exercises after coronary artery bypass graft surgery had significantly smaller atelectatic areas and better pulmonary function on the fourth postoperative day compared with a CG performing no exercises.
Inspiratory muscle training
Bissett et al. (2016)³⁴	Inspiratory muscle training once daily, five days/week for two weeks and usual care vs usual care.	Lung function Dyspnea	Inspiratory muscle training following successful weaning increases inspiratory muscle strength and quality of life, but cannot confidently rule out an associated increased risk of in-hospital mortality.
Caruso et al. (2005)³⁵	Training the inspiratory muscles twice a day (adjusting the trigger sensitivity threshold of the ventilator, based on the maximal inspiratory pressure) vs no training.	Duration of MV Weaning duration Reintubation rate Lung function	In acute critically ill patients, inspiratory muscle training resulted in no significant differences between the groups.
Early exercise training
Medrinal et al. (2018)³⁶	Four bed exercises were evaluated: passive range of movements, passive cycle-ergometry, quadriceps electrical stimulation, functional electrical stimulation (FES) cycling.	Lung function Vital signs Muscle oxygen uptake	FES cycling was the only exercise that increased cardiac output and produced sufficient intensity of muscle work.
Porta et al. (2005)²²	Supported arm exercise training, general physiotherapy vs general physiotherapy alone.	Weaning duration Lung function Laboratory results Inspiratory muscle strength Dyspnea	Early upper limb exercise training was feasible in patients recently weaned from MV and could enhance the effects of general physiotherapy.
Dong et al. (2014)³⁷	Rehabilitation therapy twice daily (heading up actively, transferring from supine position to sitting position, sitting at the edge of the bed, sitting in chair, transferring from sitting to standing, and ambulating bedside) vs standard nursing care.	Days to first out of bed Duration of MV Ventilator parameters PaO₂/FiO₂	Early rehabilitation therapy was feasible and effective in improving outcomes, such as earlier days ‘first out of bed’, duration of MV, and length of ICU stay.
Schweickert et al. (2009)²	Exercise and mobilization, simple daily awakening vs daily awakening and therapy as ordered by the primary care team.	Ventilator-free days	Exercise and mobilization resulted in better functional outcomes at hospital discharge, a shorter duration of delirium, and more ventilator-free days compared with standard care.
Nava (1998)³⁸	Pulmonary rehabilitation, passive mobilization (step I), early deambulation (step II), respiratory and lower skeletal muscle training (step III), and eventually lower extremity training on a treadmill (step IV) vs standard medical therapy, plus a basic deambulation program.	Laboratory results Lung function Maximal inspiratory pressure Six-minute walking distance Dyspnea score	Patients in the IG receiving early deambulation and mobilization improved in dyspnea score and walking distance at discharge.
Dong et al. (2016)³⁹	Early rehabilitation (head up, transferring from supination to sitting, sitting on the edge of bed, sitting in a chair, transferring from sitting to standing, walking along a bed) vs rehabilitation therapy after leaving the ICU.	Duration of MV Vital signs Electrocardiograms	The results showed decreased time on MV, and decreased ICU and hospital lengths of stay. The study provided evidence supporting the application of early rehabilitation therapy in patients requiring prolonged MV after coronary artery bypass surgery.
Position-specific optimization
Gutierrez et al. (2010)⁴⁰	Supine chest optimization vs Trendelenburg chest optimization (head-down position). Both groups received chest optimization procedures and spontaneous breathing trials.	Spontaneous breathing trial duration Cardiac output Lung function Laboratory results	These preliminary findings suggest the importance of proper recumbent body position during evidence-based, protocol-guided multimodal chest physiotherapy for ventilator-dependent patients with low spinal cord injury.
Chang et al. (2011)⁴¹	Transferred from bed to armchair and rested for at least 30 min, based on the individual patient’s tolerance vs patients in a semi-recumbent position.	Rapid shallow breathing index Lung function Vital signs	Six days of chair-sitting exercise training did not significantly improve respiratory muscle function in patients receiving MV.
Thomas et al. (2014)⁴²	Passively mobilized from supine into a seated position vs from supine to a semi-recumbent position (> 45-degree backrest elevation in bed).	Laboratory results Ventilator parameters Lung function Shallow breathing index Vital signs	Neither position resulted in significant changes in respiratory or hemodynamic parameters.
Nonpharmacological interventions
Tsay et al. (2005)²⁴	Daily acupressure therapy, massage treatment for 10 days vs massage treatment and handholding for 10 days.	Dyspnea Vital signs Duration of MV	Acupressure therapy could decrease sympathetic stimulation and improve perceived symptoms of dyspnea and anxiety in COPD patients who are using prolonged MV.
Akgul et al. (2016)⁴³	Preprocedural hypnosis by anesthesiologist vs information alone regarding surgical intervention given by the same anesthesiologist.	MV duration	Hypnosis sessions prior to surgery resulted in decreased presurgical anxiety, better pain control and reduced MV use assistance following coronary artery bypass grafting.
Han et al. (2010)⁴⁴	One music listening group (headphones with music), one placebo group (headphones, no music), and one CG (rest without music or headphones).	Vital signs	Short-term therapeutic effects of music listening, can result in reduction of physiological stress arising from anxiety in patients receiving MV.
Yaman Aktas and Karabulut (2015)⁴⁵	Listening to music 20 min before and after endotracheal aspiration vs no intervention.	Vital signs	Music therapy could be effective practice for nurses attempting to reduce patients’ pain and control sedation level in patients on MV during endotracheal aspiration.
Yadak et al. (2019)⁴⁶	30 min of Holy Quran recitation during weaning from MV vs 30 min rest in bed before the start of weaning.	Lung function Ventilator parameters Rapid shallow breathing index Negative inspiratory flow	The study showed no effect of the intervention.

Notes: ICU: intensive care unit; CT: computed tomography; CG: control group; IG: intervention group; MV: mechanical ventilation; VAP: ventilator-associated pneumonia; vs: versus; NIV: noninvasive ventilation; Pao2/Fio2 ratio: partial pressure of arterial oxygen to fractional of inspired oxygen.

Results

The systematic database search yielded 1190 records. After removing duplicates (n = 334), conference abstracts (n = 315), and records not in English (n = 70), 471 records remained, the titles and abstracts of which we read. After excluding records not fitting the inclusion criteria (n = 381), 90 articles were included to read as full-text articles. Of these, 63 articles were excluded because the studies did not include breathing difficulties (n = 28); they were not original (n = 32); or because they involved a technical intervention (n = 3). This left 27 studies for analysis.

The studies included in this review were published over 20 years (from 1998 to 2018), and represented countries all over the world (for details see Table 2). In all, 1621 patients were included. Most of the studies (n = 24) included mechanically ventilated patients. However, one study included patients receiving NIV,²¹ one included patients recently weaned from ventilation,²² and one included patients not receiving any type of ventilation.²³

The design in 26 of the 27 studies was that of a randomized controlled trial (RCT), and one had a two-group experimental design with repeated measures.²⁴ Eight of the RCTs had a crossover design. Overall, the interventions used in the included studies could be divided into six types: chest physiotherapy (n = 9); breathing techniques (n = 2); inspiratory muscle training (n = 2); early exercise training (n = 6); position-specific optimization (n = 3); and other nonpharmacological interventions (n = 5). For an overview of the countries of origin, aims, study populations, designs, interventions, respiratory outcomes, and key findings, see Tables 2 and 3.

Discussion

Chest physiotherapy

We identified nine original research studies investigating the effects of chest physiotherapy in ICU patients.^25–33 These studies included 533 patients, a strength when evaluating the effect of such interventions. Chest physiotherapy includes several different interventions such as thoracic squeezing, expiratory rib cage compression and chest wall percussion, or different combinations of interventions, such as positioning, manual hyperinflation, and suctioning. Regarding the respiratory effects of these interventions in ICU patients, several studies suggest that chest physiotherapy has positive effects for them, such as a decrease in the occurrence of ventilator-associated pneumonia,²⁷ increased removal of airway secretions,²⁸,²⁹ accelerated weaning from mechanical ventilation,³⁰ and accelerated ICU discharge.³⁰ Other studies show no effects of chest physiotherapy interventions.^31–33 However, when evaluating the effects of these interventions, there was a challenge in that several of the studies included mixed interventions. For example, in one study, chest wall percussion was combined with positioning, manual hyperinflation, and suctioning.²⁷ These multimodal interventions make it difficult to decide which of the interventions, or a combination thereof, was associated with the findings.

Breathing techniques

Only two of the included studies had interventions regarding breathing techniques.²¹,²³ The breathing techniques used in these studies were either an active cycle of breathing exercises²¹ (4–6 breathing control breaths, 3–4 thoracic expansion exercises, and the forced expiration technique including 4–6 breathing control breaths combined with 2–3 huffs), or deep-breathing exercises²³ (30 slow, deep breaths performed with a positive expiratory pressure blow-bottle device). These two studies included 124 patients. The patients were either receiving NIV for acute hypercapnic respiratory failure or were nonmechanically ventilated patients recovering after coronary bypass grafting. The two studies suggested that these breathing techniques showed patients had shorter times requiring NIV, smaller atelectatic areas, and better pulmonary function. However, it is worth noting that deep-breathing intervention did not show any effect on arterial oxygen tension, carbon dioxide tension, or durations of ICU or hospital stay. One of the studies evaluated the patients’ subjective experience. In the deep-breathing group, 72% of the patients experienced a subjective benefit from the exercises.²³

Inspiratory muscle training

Regarding inspiratory muscle training, only two studies were included.³⁴,³⁵ Patients enrolled in these two studies were ventilated mechanically or newly extubated. Training was performed by adjusting the trigger sensitivity threshold of the ventilator,³¹ or by using an inspiratory muscle training device.³⁰ Only a small number of patients were included in these studies (n = 95) which might diminish the generalizability of the findings. One of these studies showed increased inspiratory muscle strength,³⁴ but in the other this tended to stay constant.³⁵ These two studies showed no statistically significant differences in fatigue resistance index, physical function, dyspnea,³⁴ weaning duration, and reintubation rate.³⁵ Even if the interventions in these two studies were more technical than in the other studies included, one of them evaluated the patients’ quality of life, and revealed that improvement in this measure was greater in the intervention group compared with the control group.³⁴

Early exercise training

Six different studies included interventions regarding early exercise training.²,²²,^36–39 These interventions included a passive range of movements, passive cycle-ergometry, electrical stimulation of the quadriceps muscles, functional electrical stimulation combined with cycling, supported arm exercise training, and head-raising, transferring from supination to sitting, sitting on the edge of the bed, sitting in a chair, transferring from sitting to standing, and walking alongside a bed. Several positive effects of these interventions were found, such as earlier ‘first day out of bed’,³⁷ shorter duration of delirium,² improvement in the dyspnea score,³⁸ and decreased durations of mechanical ventilation, and hospital and ICU stays.³⁹ One strength of this form of intervention was that 435 patients were included. However, the studies included several different interventions, which made it difficult to compare the results with each other and with the overall findings. There was also a limitation in that a definition of ‘early’ was not clear in several of the studies using this intervention.

Position-specific optimization

Three studies included in this category evaluated the effect of position-specific optimization.^40–42 The interventions included different position-specific chest optimizations, chair-sitting, and semi-recumbent and sitting positions. One study evaluated whether position-specific chest optimization was associated with changes in the duration of a trial of spontaneous breathing.⁴⁰ These preliminary findings suggest the importance of proper recumbent body position during evidence-based, protocol-guided multimodal chest physiotherapy for ventilator-dependent patients with low spinal cord injuries. It is worth noting that only 12 patients were included in this study. Another study evaluated chair-sitting exercise training.⁴¹ The intervention did not significantly improve respiratory muscle function in mechanically ventilated patients. The third study compared the effect of semi-recumbent and sitting positions.⁴² Neither patient position resulted in significant changes in respiratory or hemodynamic parameters. Both positions can be applied safely in patients being weaned from ventilation. It is worth noting that only a few patients (n = 80) were included in these three studies (range 12–34 per study).

Nonpharmacological interventions

Five studies (n = 354 patients) were included in the group of interventions we have called nonpharmacological.²⁴,^43–46 The interventions included acupressure therapy,²⁴ clinical hypnotherapy,⁴³ listening to music,⁴⁴,⁴⁵ and listening to recitations from the Holy Quran.⁴⁶ Several of them evaluated symptoms such as anxiety and pain. However, respiratory measures were often secondary outcomes, so these studies have been included here with caution. Acupressure therapy helped decrease sympathetic stimulation and improve perceived symptoms of dyspnea and anxiety in patients with chronic obstructive pulmonary disease.²⁴ Hypnosis prior to surgery was an effective complementary method in decreasing presurgical anxiety, and resulted in a reduced need for ventilator assistance following coronary artery bypass grafting.⁴³ One study showed short-term therapeutic effects of listening to music, resulting in substantial reductions in physiological stress responses (including respiratory rate) arising from anxiety in mechanically ventilated patients.⁴⁴ Another study showed that music therapy could be effective in reducing patients’ pain and controlling the sedation level in mechanically ventilated patients during endotracheal aspiration,⁴⁵ but there were no differences in vital signs such as oxygen saturation. Finally, listening to recitations from the Holy Quran showed no positive effects on rapid shallow breathing index, respiratory rate, heart rate, oxygen saturation, exhaled carbon dioxide, or blood pressure.⁴⁶ As the interventions in this category varied widely between studies, it is difficult to conclude whether they might be effective in targeting breathing difficulties in ICU patients.

Interventions needing further investigation

It is interesting that alternative methods such as nonpharmacological therapies could be useful and used as adjuncts when treating patients in an ICU. Scoping reviews of other areas, such as pain relief, suggest the use of comprehensive multimodal interventions to investigate the effects of nonpharmacological treatment protocols on pain intensity and pain proportion and their impact on opioid consumption,⁴⁷ as the possibly serious adverse effects of these drugs should be considered when applied in treatment.⁴⁸ Nonpharmacological and nontechnical interventions have few negative effects, are cheap, easy to provide, and safe,⁴⁹ and might be beneficial when combined with classical pharmacological therapies. Several single studies included here found positive effects on some respiratory outcomes in ICU patients. However, it is difficult to recommend which nonpharmacological or nontechnical nursing interventions to use. There were several limitations in these studies regarding the effects of the interventions for ICU patients with breathing difficulties. Because of the diversity of interventions, low number of studies, and small numbers of patients included in the studies, it was impossible to perform statistical analyses for effects using meta-analysis. Even though some studies included many patients, several included as few as 12, 18, or 20, which could have introduced the possibility of selection bias. The evidence we included was sometimes further hampered by unclear descriptions of methods, and different study populations, which made it difficult to draw firm conclusions. Several studies also had multimodal interventions, which made it difficult to determine the causes of any effects. In addition, some outcomes were short-term measures during ICU treatment (e.g. effects on vital signs, aspiration of secretions, oxygenation saturation levels, other blood gas values, and atelectasis), while other outcomes were longer term (e.g. duration of mechanical ventilation, length of ICU stay, and mortality rates). Note that some of the interventions in the included studies were short and repeated only a few times. ICU patients with breathing difficulties could be part of a long treatment chain during hospitalization. When evaluating the long-term effects of different short-term interventions, it is difficult to distinguish between the effects of the selected interventions and other interfering elements during the treatment chain.

The aims of this study were to identify and evaluate the evidence base for interventions targeting breathing difficulties in ICU patients, and to propose interventions and further investigations. However, it is not clear which type of healthcare professional should be responsible for performing the interventions described here. Some of the interventions, such as chest physiotherapy and breathing techniques, might be regarded as the physiotherapist’s field. However, nurses are at the patient’s bedside most of the day, and interventions such as different position-specific optimization, breathing techniques, and rib cage compression might be appropriate for them to perform during the day. Members of several different professions might perform interventions for patients in an ICU, based upon availability, culture, and professional description at each hospital. However, coordinated teamwork between the different healthcare professional groups might be the best option.

ICU patients are a vulnerable patient group. Breathing difficulties such as dyspnea are shown to be among the most distressing symptoms in ICU patients.¹² However, even though breathing difficulties was the main focus in the present study, research shows that ICU patients experience and suffer from several distressing symptoms during their ICU stay. New research highlights for example that dyspnea, pain, and thirst are the most prevalent, intense, and distressing symptoms for ICU patients,⁵⁰ in addition to anxiety, poor sleep quality and/or insomnia.¹³ In addition, these symptoms also might have an impact on each other.⁵¹ The findings stress the importance of nursing assessing several symptoms in ICU patients, focusing on the fact that different symptoms might have an impact on each other, and being aware of the complexity in symptom burden in these patients. Only in this way, a holistic care of the ICU patients may be performed.

Limitations

Our scoping review has some limitations. The search strategy in the present study could have been made even more comprehensive. It may have yielded more relevant studies. In addition, this was a scoping study and there are several limitations to such methods.²⁰ For example, they do not appraise the quality of evidence in the primary research reports in any formal sense. The quantity of data generated can be considerable, which can lead to difficult decisions about how far the breadth of information might be more important than its depth. In addition, a scoping study does not address the issue of the ‘synthesis’ of any particular intervention. However, scoping studies provide a narrative or descriptive account of available research and this was warranted for ICU patients with breathing difficulties. Therefore, we think the scoping method was suitable for the aim of this study.

Conclusions

Several of the interventions used to assist ICU patients with breathing difficulties showed beneficial effects. Some interventions also revealed effects other than respiratory, such as lowering anxiety and pain, which in turn may contribute to positive respiratory effects. However, because of limitations in several of the studies included in this review, the low numbers of studies and few patients included, our findings are inconclusive. We recommend further research on this topic.

Footnotes

Acknowledgments

We would like to thank Julie Skattebu who participated in this study by carrying out the literature search. We also acknowledge Østfold University College for funding the study.

Funding

Østfold University College funded the study.

Conflict of interest

The authors declare that there is no conflict of interest.

ORCID iD

Brita F. Olsen

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