Outcomes of Incentive Spirometry for Patients Undergoing Coronary Artery Bypass Surgery: A Randomised Controlled Trial

ABSTRACT

Background

Incentive spirometry is used in addition to care, especially in reducing pulmonary complications after surgery. Complications in the cardiovascular and pulmonary systems can basically be determined by blood values and vital signs, which are important objective data of haemodynamics.

Aim

This study aimed to test the hypothesis that the use of incentive spirometry in conjunction with postoperative pulmonary rehabilitation care has a notable impact on arterial blood gas, oxygen saturation (SpO2) and vital signs.

Methods

This randomised, controlled trial used repeated‐measures design. It was conducted between 2021 and 2022, and data from 58 patients who underwent coronary artery bypass graft surgery at the cardiovascular surgery clinic of a university hospital were analysed. All patients received pulmonary rehabilitation, and incentive spirometry was added for the experimental group.

Results

In the experimental group, on post‐op day 3, the arterial partial pressure of oxygen (PaO2) (p = 0.01), arterial oxygen saturation (SaO2) (p = 0.002) and oxygen saturation (SpO2) (p < 0.001) values were statistically significantly higher. Additionally, on post‐op day 3 the experimental group had significantly lower systolic blood pressure (p = 0.03), diastolic blood pressure (p = 0.004) and respiratory rate (p < 0.001).

Conclusion

Incentive spirometry after coronary artery bypass graft surgery improves oxygen levels and vital signs.

Summary.

What is already known about this topic?

• The incidence of pulmonary complications following cardiovascular surgery is high. Nurses play a crucial role in mitigating these complications.

• To prevent pulmonary issues, it is essential to implement techniques that enhance respiratory muscles and augment lung capacity, particularly in the preoperative and postoperative periods.

• One such method for improving pulmonary function is incentive spirometry, designed to work the lungs with maximal inspiration. Additionally, it is recommended to be employed in conjunction with pulmonary rehabilitation techniques.

What this paper adds

• The findings of this study highlight the combined benefits of incentive spirometry and pulmonary rehabilitation techniques in optimising both pulmonary and cardiovascular recovery.

• The provision of support for the use of spirometry in conjunction with pulmonary rehabilitation techniques in the context of cardiovascular surgery contributes a non‐pharmacological approach that nurses can employ safely in the postoperative period.

The implications of this paper

• The regular use of spirometry has been demonstrated to have beneficial outcomes with respect to oxygen levels and vital signs in patients in the postoperative period.

• Incentive spirometry can enhance the quality of patient care and reduce complications.

1. Introduction

In cases of coronary artery disease, a form of cardiovascular disease (CVD), coronary artery bypass graft (CABG) surgery can improve quality of life and reduce symptoms (Sanders et al. 2022). Pulmonary complications (PC) are associated with significant mortality and morbidity following CABG surgery (Kaya and Şenturan 2016). The reported prevalence of postoperative (post‐op) PC varies between 1% and 23% and occurs most frequently after cardiac surgery among all surgical procedures (Miskovic and Lumb 2017; Audet et al. 2021).

Pulmonary rehabilitation (PR) techniques are recommended for the prevention of PC in the perioperative periods (Lumb 2019). Incentive spirometry (IS), one of these techniques, is defined as a device that provides respiratory control and maximal inspiration without resistive loads. It has been shown to increase lung volumes and diaphragm mobility, strengthen respiratory muscles and thus reduce PC (Liang et al. 2024). It is also a patient‐driven and independently applicable method (Karaçay 2019; Boden et al. 2018). Effective IS use results in negative intrathoracic pressure sufficient to keep all alveoli open at the end of inspiration (Heydari and Farzad 2015; Martin et al. 2018). The frequency of use is not clear, and guidelines recommend performing it at regular intervals, with the number determined by the patient's comfort level (Restrepo et al. 2011).

There is some uncertainty surrounding the use of IS in preventing post‐op PC. While some studies have reported that IS does not improve post‐op pulmonary function (PF) tests (Tyson et al. 2015; Moradian et al. 2019), other studies have found that it can enhance patient ventilation and oxygenation in pulmonary care after CABG (Ferreira et al. 2010; Sweity et al. 2021).

According to the guidelines published by the American Thoracic Society (ATS) and the American College of Chest Physicians (ACCP), IS is recommended to be used with PR techniques, such as early mobilisation, coughing‐deep breathing exercises to prevent possible PC in the post‐op period in patients who undergo cardiac surgery (Graham et al. 2019). Considering both the current debates and the guideline recommendations for the benefit of patients, it was decided to use IS with PR techniques in this study.

IS is an effective tool in the postoperative period, as it facilitates full lung expansion and improves oxygenation levels (Liang et al. 2024). Enhanced oxygenation reduces the workload on the cardiovascular system, contributing to the stabilisation of vital signs such as blood pressure, respiration and heart rate (Palermo et al. 2024; Verhoeff and Mitchell 2017). Vital signs are widely recognised as critical parameters in the assessment of surgical patients, reflecting the health status of both the cardiovascular and pulmonary systems (Elliott 2021). Impaired PF during the surgical process may affect respiration, potentially influencing cardiac workload and causing measurable changes in pulse and blood pressure (Spinelli et al. 2024; Büyükçamsarı and Eti Aslan 2018). Based on these connections, it was considered that IS used in cardiovascular surgery patients directly affects the pulmonary system and indirectly affects the cardiac system by enhancing oxygenation, and the study aimed to investigate how these effects are reflected in vital signs.

The purpose of this research was determining the outcomes of IS on arterial blood gas (ABG), oxygen saturation (SpO2) and vital signs when used in conjunction with post‐op PR care, including respiratory/cough exercises, pain management and early mobilisation. To achieve this aim, in this study, IS results were compared with known oxygen values, as well as with vital signs values, which, as far as is known, has not previously been presented in the literature.

The alternative hypothesis (H1) tested in this study was that the use of IS in conjunction with postoperative PR care has a notable impact on ABG, peripheral oxygen saturation (SpO2) and vital signs.

2. Methods

2.1. Study Design

For this research, randomised controlled design with repeated measures was used, and the patients were divided into two different groups, as the control (non‐IS) and experimental (IS‐Exp). The study adhered to the Consolidated Standards of Reporting Trials (CONSORT) 2010 guidelines. This single‐centre study was registered online, in the Clinical Trials Database (https://clinicaltrials.gov; NCT05192785).

2.2. Population and Sample

This study evaluated patients who underwent CABG surgery at the cardiovascular surgery clinic of a university hospital between 2021 and 2022. In this study, 102 patients were assessed for eligibility, 73 were randomised and 58 patients were analysed (28 in the experimental [IS‐Exp] group and 30 in the control [non‐IS] group).

2.2.1. Sample Size and Power

Power analysis was conducted via the use of G*Power v.3.0.10 based on data from a study previously published by Yazdannik et al. (2016). The power of the study was calculated as 85% with an effect size of F = 0.4610, 5% margin of error and n = 27 (total 54) as the sample size. In order to accommodate the potential for treatment discontinuation over the course of the follow‐up period, it was determined that approximately 30% more patients should be included in each group.

In total, 102 patients were assessed for eligibility. Of these, 29 were not included due to the inclusion criteria not being met (n = 15), declining participation (n = 11) and administrative and organisational reasons (n = 3). Thus, 73 patients (with 35 in the IS‐Exp group and 38 in the non‐IS group) who met the study's selection criteria were randomised. During the research process, seven patients from the IS‐Exp group were excluded from the study: Two patients did not regularly use the IS, one patient refused to continue to participate, three patients had unstable clinical conditions and one patient had re‐sternotomy. In the non‐IS group, eight patients were excluded: One patient refused to continue to participate, two patients had unstable clinical conditions, three patients did not regularly use the PR (including respiratory/cough exercises, pain management and early mobilisation), one patient required prolonged mechanical ventilation and one patient passed away. Thus, 58 patients were analysed (28 in the IS‐Exp group and 30 in the non‐IS group) (Figure 1).

FIGURE 1.

CONSORT flow diagram.

2.2.2. Randomisation and Blinding

The allocation of patients to groups was performed using a simple randomisation method with a random number table generated by a computerised random number generator. The random allocation sequence was implemented using sequentially numbered envelopes, which were sealed in order to maintain confidentiality. A single blind method was utilised and during the randomisation process, with the principal investigator remaining blind to the group assignments of the patients. Additionally, the statistician was blinded to the groups in order to enhance the impartiality and reliability of the results. There was no cross‐over between groups. Therefore, the analysis was conducted on an ‘as randomised’ basis.

2.2.3. Participants

The study included participants who were willing and able to communicate, had a stable clinical condition, had no difficulty with their hearing, had no history of psychiatric and/or mental illnesses and were undergoing their first CABG (nonemergency). Patients with similar echocardiographic features (ejection fractions, valvular functions or pulmonary arterial pressures) and cross‐clamping times during surgery were included, as these factors can affect PF in the post‐op period. Those who had a clinical situation that was unstable, did not agree to participate, had a history of chronic obstructive pulmonary disease or chronic kidney failure or had severe hemodynamic dysfunction were excluded from the study. Additionally, patients requiring sternotomy or prolonged mechanical ventilation were also eliminated from the study.

2.3. Data Collection

The researcher provided consent and information forms to patients who met the sampling criteria during the preoperative (pre‐op) period, beginning with admission of the patient to the clinic.

The researcher developed a Personal Information form, based on a review conducted of previously published studies, that comprised questions regarding age, gender, body mass index (BMI), chronic disease status, the use of alcohol and cigarettes, physical exercise habits, dietary habits and American Society of Anesthesiologists classification (ASA Classification 2022). Routinely collected vital signs, and ABG and SpO2 values were all recorded on an Application Information (AI) form. Among ABG values, arterial partial pressure of carbon dioxide (PaCO2), arterial partial pressure of oxygen (PaO2) and arterial oxygen saturation (SaO2) were evaluated. Additionally, peripheral oxygen saturation level (SpO2) was measured by pulse oximetry. Among the vital signs, systolic blood pressure, diastolic blood pressure, respiratory rate and pulse rate were measured. The ABG and SpO2 levels and vital signs were all recorded on the AI form during the resting period of the patients at the end of post‐op days 1, 2 and 3.

2.4. Interventions

2.4.1. IS‐Exp (Experimental) Group

The IS used in the study had three separate compartments and a breathing tube with a mouthpiece at the end. The compartments contained coloured balls, with volumes of 600, 900 and 1200 mL, respectively. The flow‐oriented IS used in the study was provided by a medical product company called Plasti‐med.

The use of IS with a breathing‐cough exercise was explained, then demonstrated and applied by the researcher for approximately 2 days preoperatively and during the hospitalisation days (in the intensive care unit and clinic) after extubation in the post‐op period when the patient was fully awake. The IS applications included a total of 10 to 20 breaths, every 1 to 2 h, depending on the patients' tolerance. Reminders to perform the practices during time intervals when the patient was awake were provided by the researcher during the day shift and by the nurses during the night shift.

The patients were first given deep breathing exercises, followed by IS application, and finally the process was completed with coughing exercises. During the IS, the hospital bed was raised to a 45° angle, and then, the patient was put into a long‐sitting position. They were asked to tightly wrap and stabilise the IS mouthpiece, making sure that they did not have any gaps between their lips. They were instructed to deeply and slowly inhale to lift the balls to the target position. The patients were asked to watch the balls for visual feedback. Then, the mouthpiece was removed, and they were asked to hold their breath for between 3 and 5 s, and then exhale normally. The exercise was repeated according to patients' tolerance 5–10 times, and after every five exercises, coughing exercises were performed.

Early mobilisation was started simultaneously and continued throughout the hospital stay. In addition, all of the patients were assessed for pain using a pain scale every 4–6 h before the IS application and pain management was ensured based on the scale results (using paracetamol and/or opioids, in line with clinical routine).

2.4.2. Non‐IS (Control) Group

The non‐IS group patients received all of the interventions, except IS, i.e. deep breathing and coughing, pain assessment and early mobilisation.

2.5. Data Analysis

The IBM SPSS Statistics for Windows 24.0 (IBM Corp., Armonk, NY, USA) was used when conducting the statistical analyses. When interpreting the findings, descriptive statistics and frequency tables were used. Normally distributed measurement values were determined using parametric methods, and non‐normally distributed measurement values were determined using nonparametric methods. In accordance with these methods, the comparison of the measurement values of two independent groups was performed using independent sample t test or Mann–Whitney U test, and the comparison of the measurement values of three or more dependent groups was performed using repeated measures test or Friedman test. The relationships between two qualitative variables were examined using Pearson χ ² crosstabs. Statistical significance was accepted as 0.05 for all of the tests.

2.6. Ethical Considerations

Ethics committee approval was granted by the Non‐Invasive Clinical Research Ethics Committee for the conduct of the study (Number: 86, Decision Number: 51) and necessary institutional permissions were obtained from Çukurova University Hospital where the study was conducted (Number: 61229848‐622.01). The research was performed in line with the ethical principles stipulated within the Declaration of Helsinki (Fortaleza, Brazil, October 2013). The patients were all informed about the study, its intended aim was explained to them and they were asked to confirm their willingness to participate, both verbally and in writing. This single‐centre study was registered online, in the Clinical Trials Database (https://clinicaltrials.gov; NCT05192785).

*The study complies with the guidelines of the Consolidated Standards of Reporting Trials (CONSORT 2010).

3. Results

The differences determined in the patients' sociodemographic characteristics were not statistically significant (Table 1).

TABLE 1.

Relationships between the socio‐demographic characteristics of the patients.

Variable (N = 58)	Experimental group (n = 28)		Control group (n = 30)		Statistical analysis*
Variable	SD		SD
Age (years)	56.35 (%) ± 13.66 (%)		57.26 (%) ± 15.96 (%)		p = 0.81
Body mass index (kg/m2)	28.63 (%) ± 4.93 (%)		26.40 (%) ± 4.15 (%)		p = 0.06
	n	%	n	%
Gender
Female	13	46.4	11	36.7	p = 0.45
Male	15	53.6	19	63.3
Chronic disease (HT + HL + HF + KY + DM etc.)
Yes	21	75	23	76.7	0.88
No	7	25	7	23.3
Smoking
Yes	17	60.7	17	56.7	0.75
No	11	39.3	13	43.3
Drinking alcohol
Yes	10	35.7	11	36.7	0.94
No	18	64.3	19	63.3
Physical exercise
Regular	5	17.9	11	36.7	p = 0.27
Irregular	8	28.6	6	20
Not exercise	15	53.6	13	43.3
Nutritional diet
Regular	5	17.9	10	33.3	p = 0.34
Irregular	10	35.7	7	23.3
Not diet	13	46.4	13	43.3
ASA class
2	8	28.6	7	23.3	p = 0.79
3	12	42.9	12	40
4	8	28.6	11	36.7

^*ASA: The American Society of Anesthesiologists; DM, diabetes mellitus; HF, heart failure; HL, hyperlipidaemia; HT, hypertension.

Between the non‐IS and IS‐Exp groups, the differences in the PaO2 values (p = 0.01), and SaO2 values (p = 0.002), from the ABG measurements on post‐op day 3 were statistically significant. Also, the differences in the SpO2 measurements on post‐op day 3 (p < 0.001) were statistically significant. The IS‐Exp group values were found to be significantly higher than those of the non‐IS group (Table 2).

TABLE 2.

Comparison of arterial blood gas and peripheral oxygen saturation parameters by group.

Variable (N = 58)	Experimental group (n = 28)	Control group (n = 30)	Statistical analysis
	$\overline{X}\underset{¯}{+}S.S.$	$\overline{X}\underset{¯}{+}S.S.$
PaCO2 (35–45 mmHg)
Preop(0)	38.20 ± 3.26	38.38 ± 3.66	p = 0.84
Postop 1.day(1)	35.85 ± 5.89	35.48 ± 6.29	p = 0.82
Postop 2.day(2)	35.59 ± 4.81	35.24 ± 6.19	p = 0.80
Postop 3.day(3)	36.06 ± 3.07	36.95 ± 4.39	p = 0.37
Statistical analysis Difference*	p = 0.08	p = 0.002 [0–1, 2]
PaO2 (80–100 mmHg)
Preop(0)	95.34 ± 5.32	94.65 ± 4.79	p = 0.60
Postop 1.day(1)	83.33 ± 6.96	84.71 ± 9.16	p = 0.52
Postop 2.day(2)	87.56 ± 7.50	86.25 ± 7.47	p = 0.50
Postop 3.day(3)	94.71 ± 5.42	90.59 ± 6.88	p = 0.01
Statistical analysis Difference	p < 0.001 [0–1, 2] [1–3] [2–3]	p < 0.001 [0–1, 2] [1–3] [2–3] [3–0]
SaO2 (%95–100)
Preop(0)	98.43 ± 1.30	98.06 ± 1.71	p = 0.35
Postop 1. day(1)	93.50 ± 3.43	93.75 ± 4.31	P = 0.80
Postop 2. day(2)	95.69 ± 2.64	95.13 ± 2.87	p = 0.42
Postop 3. day(3)	98.30 ± 1.66	96.25 ± 2.96	0.002
Statistical analysis Difference	p < 0.001 [0–1, 2] [1–2, 3] [2–3] [3–0]	p < 0.001 [0–1, 2, 3] [1–3]
SpO2 (%90–100)
Preop(0)	98.78 ± 2.42	98.85 ± 1.74	p = 0.90
Postop 1. day(1)	93.64 ± 3.63	94.98 ± 3.18	p = 0.14
Postop 2. day(2)	96.82 ± 2.49	96.28 ± 2.61	P = 0.42
Postop 3. day(3)	99.17 ± 0.88	96.71 ± 2.69	p < 0.001
Statistical analysis Difference	p < 0.001 [0–1, 2] [1–2, 3] [2–3]	p < 0.001 [0–1, 2, 3]

^*The difference variable is used to indicate which days within the group exhibit a difference. For example [1–2, 3], there is a difference between postoperative day 1 and postoperative day 2, as well as between postoperative day 1 and postoperative day 3. p‐values in bold represent statistically significant results (p < 0.05).

In the IS‐Exp group, the difference when comparing the measurement values of the ABG (PaO2: p < 0.001, SaO2: p < 0.001) and SpO2 (p < 0.001) between perioperative days was statistically significant. The post‐op day 3 values were similar to the pre‐op values, indicating that the IS‐Exp group was able to reach their pre‐op lung capacity (Table 2).

In the non‐IS group, the differences when comparing the measurement values of the ABG (PaCO2: p = 0.002, PaO2: p < 0.001, SaO2: p < 0.001) and SpO2 (p < 0.001) between perioperative days was also statistically significant. However, the post‐op values were lower than the pre‐op values, indicating that the non‐IS group were not able to reach their pre‐op lung capacity (Table 2).

The differences between the systolic blood pressure (sBP) values (p = 0.03), diastolic blood pressure (dBP) values (p = 0.004) and respiratory rate (RR) values (p < 0.001) of the measurements of the groups on post‐op day 3 were statistically significant, with the IS‐Exp group values being closer to the normal range. The difference in the pulse rate (PR) measurements on post‐op day 3 (p = 0.16) was not statistically significant (Table 3).

TABLE 3.

Comparison of vital sign parameters by groups.

Variable	Experimental group (n = 28)	Control group (n = 30)	Statistical analysis*
(N = 58)	$\overline{X}\underset{¯}{+}S.S.$	$\overline{X}\underset{¯}{+}S.S.$
Systolic blood pressure, mmHg
Preop(0)	122.08 ± 12.59	120.43 ± 9.73	p = 0.57
Postop 1.day(1)	138.03 ± 16.17	140.16 ± 15.01	P = 0.60
Postop 2.day(2)	129.53 ± 10.46	133.33 ± 9.58	p = 0.15
Postop 3.day(3)	121.39 ± 12.84	129.03 ± 14.01	p = 0.03
Statistical analysis*	p < 0.001	p < 0.001
Difference	[0–1] [1–3]	[0–1, 2, 3] [1–3]
Diastolic blood pressure, mmHg
Preop(0)	67.00 ± 7.77	65.13 ± 8.27	p = 0.38
Postop 1.day(1)	74.14 ± 9.21	78.60 ± 11.86	p = 0.11
Postop 2.day(2)	68.50 ± 8.56	72.16 ± 9.06	p = 0.12
Postop 3.day(3)	65.32 ± 5.92	71.43 ± 9.27	p = 0.004
Statistical analysis Difference	p < 0.001 [0–1] [1–3]	p < 0.001 [0–1, 2, 3] [1–2]
Respiratory rate
Preop(0)	20.21 ± 2.33	21.13 ± 1.56	p = 0.07
Postop 1.day(1)	25.14 ± 2.06	24.76 ± 2.35	P = 0.52
Postop 2.day(2)	23.75 ± 1.26	24.53 ± 2.08	P = 0.08
Postop 3.day(3)	20.96 ± 1.37	23.06 ± 1.98	p < 0.001
Statistical analysis	p < 0.001	p < 0.001
Difference	[0–1, 2] [1–2, 3] [2–3]	[0–1, 2, 3] [1–3] [2–3]
Pulse rate
Preop(0)	80.82 ± 16.84	83.76 ± 10.78	p = 0.43
Postop 1.day(1)	102.03 ± 13.11	97.16 ± 10.22	P = 0.11
Postop 2.day(2)	100.46 ± 10.85	102.10 ± 12.04	p = 0.59
Postop 3.day(3)	85.64 ± 12.68	90.10 ± 11.24	p = 0.16
Statistical analysis Difference	p < 0.001 [0–1, 2] [1–3] [2–3]	p < 0.001 [0–1, 2] [1–3] [2–3]

^*The difference variable is used to indicate which days within the group exhibit a difference. p‐values in bold represent statistically significant results (p < 0.05).

In the within‐group comparisons of PaO2, SaO2, SpO2 and vital signs of the patients in the experimental group compared with the control group, it was observed that the values of the experimental group in the postoperative period became positive day by day and got closer to the preoperative normal value (p < 0.001) (Tables 2 and 3).

4. Discussion

In recent years, a number of studies investigating the effectiveness of IS in improving PF after CABG surgery have been conducted. Our study adds to the existing literature by demonstrating that IS, when used in combination with PR, can lead to significant improvements in ABG and SpO2 levels, as well as BP and RR measurements.

In the current research, the difference in the PaO2, SaO2 and SpO2 values between the groups was statistically significant. The observed difference in the oxygen values among the patients in the IS‐Exp group suggests the positive effect of IS on PF. A study that was conducted by Yazdannik et al. (2016) found that the use of IS in 50 patients who underwent CABG surgery was significant in improving ABG parameters. Similarly, the positive outcomes of IS combined with PR were observed in other studies (Boden et al. 2018; Shakouri et al. 2015). Alam et al. (2020) reported positive effects of IS use on blood gas levels on postop day 3 after CABG. However, our average PaO₂ levels (94.71 mmHg) were higher than those reported by Alam et al. (67.2). This difference may be due to variations in patient population, protocol intensity or other factors.

The pre‐op PaO2, SaO2 and SpO2 values in the examined patients were within normal limits and decreased on post‐op (operation‐related) day 1, with gradual improvement on post‐op days 2 and 3. Although improvement was seen in both groups, it was greater in the IS‐Exp group. Thus, it was clear that IS had positive outcomes on the pulmonary system. Compliance with performing the exercises repeatedly is essential in order to ensure a therapeutic effect. The findings here are supported by some other studies, which have shown that performing maximal inspiration exercise, when it is repeated on an hourly basis following major surgeries, reduces intrapulmonary shunting and improves ventilation and perfusion mismatch and the alveolar partial PaO2 gradient (Alwekhyan et al. 2022; Ko et al. 2021). Additionally, a study that was conducted by Rizwan et al. (2012) reported significantly improved oxygenation following a series of three sets of deep breaths on post‐op day 2 after replacement of the mitral valve. A study by Benzo et al. (2011) found that pre‐op PR interventions incorporating IS improved post‐op lung re‐expansion, reduced chest tube times and decreased post‐op morbidity and the duration of hospitalisation in patients who underwent curative lung resection. Similarly, a study by Fatima and Kazmi (2021) found that IS was effective in improving the ABG and SaO2 levels in patients who underwent cardiac surgery.

In contrast, a randomised clinical trial by Manapunsopee et al. (2020) found that the use of IS did not have a significant effect on the incidence of PC in patients who underwent cardiac surgery.

There are studies in the literature reporting significant differences in PCO₂ levels (Alam et al. 2020; Fatima and Kazmi 2021). However, in our study, no statistically significant difference was observed between the groups, and PCO₂ levels were found to remain within normal limits in both groups. Nevertheless, within‐group analysis revealed a significant difference in the control group. This may be attributed to differences in clinical characteristics or other variables affecting the patients in the control group.

Eltorai et al. (2018) conducted an evaluation of studies that showed the ineffectiveness of IS, and they reported that inadequate research methodology, lack of motivation, patient noncompliance and insufficient patient supervision may have contributed to the lack of effectiveness. Pantel et al. (2017) reported, in a randomised clinical trial investigating the use of IS after surgery, that the procedure did not affect post‐op hypoxemia or PC, and the patient compliance rate was low. Different studies have suggested that IS with regular use may contribute positively to the improvement of diaphragmatic dysfunction in the post‐op period (Kumar et al. 2016; Pazzianotto‐Forti et al. 2015). In this study, the patients were reminded to use IS regularly.

In another study, it was found that the IS inspiration technique, combined with the use of expiratory positive airway pressure to improve expiration, resulted in positive effects on PF (Ferreira et al. 2010). In this current research study, using IS resulted in positive outcome with respect to PF.

Oxygenation facilitated and enhanced by IS (Restrepo et al. 2011) reduces the activation of the sympathetic nervous system, leading to decreased cardiac workload (Spinelli et al. 2024). These physiological adjustments contribute to the stabilisation of blood pressure and heart rates in postoperative patients (Elliott 2021). The deep and controlled breathing supported by IS improves venous return and cardiac output, thereby enhancing both pulmonary and cardiac functions (Verhoeff and Mitchell 2017). These mechanisms demonstrate the interconnected nature of the pulmonary and cardiovascular systems, where improved respiratory function positively influences cardiovascular parameters (Palermo et al. 2024). The present study demonstrated that IS had positive outcomes on vital sign parameters, with statistically significant improvements in sBP and dBP and RRs observed in the IS‐Exp group in comparison with the non‐IS group. Moreover, positive differences were seen post‐op in both groups, but the positive effect was greater in the IS‐Exp group.

The findings of this study highlight the combined benefits of IS and PR techniques in optimising both pulmonary and cardiovascular recovery. While previous research has primarily focused on pulmonary outcomes, such as oxygenation and lung volumes, this study broadens the understanding of IS's benefits by examining its effects on cardiovascular stability and respiratory efficiency in postoperative care. As no previous study investigating the effectiveness of IS on vital signs exists within the current literature, the results in this research could not be compared with those of earlier studies.

4.1. Limitations

Limitations of this study include the fact that the patients' maximal inspiration times (ability to keep the IS ball as high as possible) could not be controlled. Also, this study was conducted in only a single site.

5. Conclusions

The findings of the study indicated that the utilisation of IS in conjunction with PR applications during the preoperative and postoperative periods, in addition to ensuring patient compliance, resulted in favourable outcomes with regard to ABG and SpO2 values and vital signs. Nurses can contribute to the reduction of postoperative complications by educating patients on the use of IS and encouraging them to apply it regularly. Hospitals can enhance the standardisation and quality of postoperative care by integrating the routine use of IS. This study may inform future research evaluating the effectiveness of IS. Further studies on larger patient groups may enhance the generalisability of the results and provide a more detailed overview of the effectiveness of IS in different patient groups.

Author Contributions

Esma Gökçe: literature research, study design, analysis of data, manuscript preparation. Dudu Alptekin: literature research, review of manuscript. Derya Gezer: literature research, analysis of data. Refiye Akpolat: literature research, review of manuscript. Hamide Şişman: literature research, review of manuscript. Güldane Kayhanlı: data collecting. Sevban Arslan: literature research, study design, review of manuscript.

Ethics Statement

Ethics committee approval was granted by the Non‐Invasive Clinical Research Ethics Committee for the conduct of the study (Number: 86, Decision Number: 51) and necessary institutional permissions were obtained from Çukurova University Hospital where the study was conducted (Number: 61229848‐622.01). The research was performed in line with the ethical principles stipulated within the Declaration of Helsinki (Fortaleza, Brazil, October 2013). The patients were all informed about the study, its intended aim was explained to them and they were asked to confirm their willingness to participate, both verbally and in writing. This single‐centre study was registered online, in the Clinical Trials Database (https://clinicaltrials.gov; NCT05192785). *The study complies with the guidelines of the Consolidated Standards of Reporting Trials (CONSORT 2010).

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data supporting the findings of this study may be made available upon appropriate request from the corresponding author in accordance with ethical principles.