Preoperative incentive spirometry for preventing postoperative pulmonary complications in patients undergoing coronary artery bypass graft surgery: a prospective, randomized controlled trial

The study was conducted as prospective cohort, randomized controlled trial (RCT). This design was adopted due the strength of the hierarchy of scientific evidence, namely, reduced bias and more accurate results.

The participants who met the inclusion criteria were randomized into two groups according to a randomization list formatted by www.​randomization.​com.

Group 1: Incentive spirometry was utilized by the patient with ten breaths, six times per day for a period of 10 min in every session with a breathing technique for two days preoperatively. The patients were taught how to use IS by a nurse who would not be involved in the patient’s postoperative care. (Experimental group) (IS).

Group 2: No IS preoperatively, only IS postoperatively (Control Group).

The patients, health care providers included in the patient care are unaware of the treatment group allocation.

To ensure that the patients, the surgeon and the radiologist were blind to the treatment group before the study begins. The patients, surgeon, and radiologist were unaware of IS group and the surgeries performed by the same surgeon. The radiologist was also assessing the X-ray and wrote about all X-rays for all patients.

The primary outcome was defined as respiratory complications that occur within 48–72 h following surgery, which includes: atelectasis, pneumonia, pleural effusion, and Pneumothorax, which is measured by x-ray and clinical signs and symptoms [34]. Chest X-ray was examined by the radiologist for all patients and decided if atelectasis is present or not. However, the radiologist did not mention the grade or severity of the atelectasis, but they divided them to is present if atelectasis present or not, also knowing that the radiologist was blinded about the intervention or control group, also atelectasis defined as the collapse of a part of or the entire lung, which may be acute or chronic. This research refers to the characters such as X-ray, tracheal mediastinal shift deviation; reduced respiratory activity; diminished breath sounds; displacement of the trachea to the affected side; new parenchymal thickening surrounded by hyperinflated lung [14].

Secondary outcomes included hospital length of stay that was calculated by subtracting the day of admission from the day of discharge [35]. Mechanical ventilation duration in hours, oxygenation status by measuring Pao2 and SaO2 by ABG’s, and pain control using a numerical pain scale.

The participants who met the inclusion criteria and randomized to the intervention group were given a flow-based incentive spirometer and asked to use spirometry with deep-breathing exercise 2 days preoperatively until surgery. They were asked to hold the spirometer in the upright position, place their lips tightly across the spirometer mouthpiece, and then they were asked to slowly inhale air into the lungs to raise the ball to the target position. After that, the mouthpiece was removed, and patients were asked to hold their breath for at least 5 s, followed by normal expiration. Incentive spirometry was done with ten breaths, six times per day for a period of 10 min every session before surgery, according to literature and An-Najah National University hospital.

All patients who enrolled in the intervention were 100% compliant with preoperative IS after teaching him how to use the IS; also, reminder was used by nurses by a drug sheet that wrote by the doctors every 4 h. Also, the nurses ensured the patients' practice of IS, knowing that all patients did not know about preoperative IS tend to be healthier as what literature previously said it is no benefit.

Observations and hemodynamic parameters were measured preoperatively and postoperatively. For both groups, study observations were recorded every 6 h. Both groups postoperative received the same intervention: the exercises began on the morning after surgery with incentive spirometry, deep-breathing exercise and physiotherapy after Extubation, and early mobilization, in accordance with An-Najah University Hospital protocol. A datasheet containing the following information was filled out for each patient: name, age; height; weight; body mass index, respiratory status, medical history, presence of respiratory complications, duration of MV, and numerical pain scale and hospital length of stay.

The data collection sheet was prepared after going through the linked literature and with the supervision of experts in the field. Content validity is defined as “the degree to which objects in an instrument reflect the content universe to which the instrument will be generalized [36]. Content validity was applied while the datasheet was developed to ensure that it included all essential items [37, 38]. The assessment method for determining the validity of the data sheet included literature reviews and then follow-ups with evaluation by expert judges or panels (two intensivists, one anesthesiologist, and three nurses in critical care), and all experts’ suggestions were taken into account.

Thoracic x-rays were taken during the preoperative period and immediately following surgery in the intensive cardiac care unit (ICCU), on the ward, once the drains had been removed (48 h after surgery), and on discharge from the hospital. X-ray examinations were performed at the same frequency for all patients in both groups.

(AN-Najah National University Hospital protocol).

All patients in both groups received the same anaesthesia technique and ventilation in the operation room.

A standard induction for cardiac anaesthesia started with a facial mask inhaling sevoflurane 0–8% in 100% oxygen and fresh gas flow of 3 L/min for 5 min. After that, patients were given IV anaesthesia Propofol 2 mg/kg IV and tracheal intubation was facilitated with rocuronium 1.5–2 mg/kg with fentanyl 2–20 mcg/kg/dose initially.

Anaesthesia was maintained with sevoflurane 0–3% in 50% oxygen and 50% air. Neuromuscular blockade was maintained with increments of atracurium with this equation: 0.3(dose)*kg/4(concentration/ml) = ml/hr, fentanyle was used to provide intraoperative analgesia with this equation: 2(dose)*kg/20(concentration/ml) = ml/hr as 1–2 mcg/kg/hr maintenance.

For special cases like decreased ejection fraction and left main coronary disease, etomidate 0.3–0.6 mg/kg was used.

The institutional Review Board (IRB) of An-Najah National University approved the study. Consent forms were obtained from the patients prior to participation and the study was registered in the Thai Clinical Trials Registry (No. TCTR20201020005). All patients were given both verbal and written information about the aim and objectives of the study before considering participation in the study. The study was conducted in accordance with the World Health Organization Declaration on the Ethical Principles of Helsinki for Medical Research on Humans (2013) [39].

Demographic data were comparable between the two groups (Table 1). All patients in the two groups were comparable in terms of age, gender, comorbidity, smoking, and BMI. Hemodynamic parameters and other observations were recorded before the operation, postoperatively, and three days postoperatively. There are no significant differences between the IS Group and the Control Group in all general characteristics of patients exhibited at the table 0.05 level (p value > 0.05).

Figure 2 shows the respiratory complications of atelectasis among the IS Group and the Control Group. On the operation day, there was no atelectasis diagnosed in either group. On the first day, of the 22 patients with atelectasis, seven were in the IS group and 15 in the Control Group, showing statistically significant differences (p value = 0.045). On the next day, the number of patients in the Control Group with atelectasis was 17, and in the IS group, it was 8, with statistically significant differences (p value = 0.030). Furthermore, the third day showed four clients with atelectasis in the Control Group and zero patients in the IS group, with statistically significant differences (p value = 0.040). On the other hand, there were no statistically significant differences between the groups in other respiratory complications.

Figure 3 shows that there are significant differences between the IS Group and the Control Group in the length of stay in the intensive cardiac care unit (ICCU), intermediate cardiac care unit (IMCCU), and hospital discharge (p value =  < 0.001). The IS Group average was three days in ICCU, two and a half days in IMCCU. In contrast, the Control Group average was four days in ICCU and three days in IMCCU.

Figure 4 shows that there are significant differences between the IS Group and the Control Group in the duration of time spent in mechanical ventilation in the intensive cardiac care unit (ICCU). Patients in the IS Group spent 4 h, while patients in the Control Group spent 6 h (p value =  < 0.001). The median hours spent was 5 h. However, the incidence of re-intubation was (0.0%) with (p value =  > 0.999).

In the current study, there was a significant decrease in the incidence of atelectasis in the IS Group. This finding is consistent with Diken and Özyalçın [31], who conducted an RCT that involved 108 patients divided into two groups: IS preoperative and routine care for control, with a body mass index over 30 kg/m² and without previous pulmonary disease. In Diken and Özyalçın’s study, patients with atelectasis were predominantly higher in the Control Group compared to the IS Group (18 vs. 7 patients, respectively) (p = 0.0036). The current findings also agree with Gilani et al. [40], who conducted an RCT that showed the incidence of postoperative atelectasis was 14.10% in Group I (IS) and 27.10% in Group II patients (control) (p = 0.04). Moreover, the current study results are consistent with Oshvandi et al. [11], who was showed that the occurrence of atelectasis, respiratory status, dyspnea, and sweating showed a significant difference between the IS and control groups at all hours after surgery (p < 0.001). Furthermore, the results are also in agreement with Shaban et al. [10], who showed the incidence rate of atelectasis in the experimental group was (26.7%), less than the control group (56.7%) with (p = 0.01). In addition, the study results also agree with Nardi et al. [19], who revealed that better clinical results for respiratory and musculoskeletal function were found in the groups preoperatively treated with physiotherapeutic protocols immediately before as well as after cardiac surgery. Just the same results were confirmed by Yánez-Brage et al. [12] in their observational study, which was conducted on 263 patients and revealed that preoperative physiotherapy (involving incentive spirometry, deep-breathing exercises, assisted coughing and early ambulation) after off-pump CABG surgery was related to a lower incidence of atelectasis.

Conversely, the current study is inconsistent with a study conducted by Moradian et al. [32]. This study examined 100 participants and found no significant differences between the IS and control groups in terms of atelectasis and hypoxemia (p value > 0.05). Freitas et al.[13] also revealed no evidence of a difference between groups in the incidence of PPCs with IS and treatment with physical therapy, positive-pressure breathing techniques, active cycle of breathing, or preoperative patient education and worse pulmonary function and arterial oxygenation. Eltorai et al. [25] investigated the clinical effectiveness of incentive spirometry and found that there was narrow evidence to support its advantages and an absence of a harmonized protocols for its use. In addition, Overend et al. [21] conducted a systematic review study and concluded that evidence does not support the use of IS for decreasing the incidence of PPCs.

The current results showed a significant improvement in Pao2, Sao2, and SPO2 in the IS Group compared to the Control Group. These results are consistent with Fayyaz et al. [28], where preoperative spirometry had improved postoperative oxygenation in the IS group to 97.29 while the control group was 93.27. These results are in line with Yazdemik et al. [29], who concluded that incentive spirometry caused a remarkable improvement of Pao2, Sao2, and SPO2. Another study conducted by Moradyan et al. [30] corresponds to the current study results and revealed that protocols for breathing exercises (deep breathing, incentive spirometry, and directed maneuvers) could improve PaO2 and SaO2. In contrast, Balandiuk and Kozlov [33] revealed that the use of an incentive spirometer preoperatively for cardiac surgery significantly improved arterial oxygenation.

Freitas et al. [13] presented results that contradict the current results. They found no differences between the study groups in terms of incentive spirometry used and found poorer lung function and status of arterial oxygenation competed with those treated with positive pressure ventilation. Diken and Özyalçın [31] also disagree with our study results after conducting RCT with the two groups and showed no change in oxygenation status for both groups. Even Afrasiabi et al. [24] reported that incentive spirometry had no significant effect on the improvement in postoperative oxygenation. In addition, Yánez-Brage et al. [12] also reported that the improvement in postoperative oxygenation using incentive spirometry is not permanent; this improvement is reversible after a short period of time. Carvalho et al. [20] in a systematic review study, reviewed 30 studies in relation to IS. They reported that there was no strong evidence to support the use of IS after CABG, and there is a need for studies to clarify the effect and justify the use of this technique.

The current results showed that the incidence of hospital length of stay for the IS Group was 6 days, while in the Control Group it was 7 days. ICU LOS for the IS Group was also reduced compared with the Control Group. This finding is consistent with Nardi et al. [19] who revealed that the hospital stay was further reduced in the IS group. In addition, Shaban et al. [10] reported the same results when they declared that the hospital length of stay decreased for the IS group compared to the control group. On the other hand, Fayyaz et al. [28] presented results that contradict the current results. They revealed that there were no differences between the groups in length of hospital stay.

The current results showed significant differences between the two groups (IS and Control) regarding mechanical ventilation time (duration), which was 4 h for the IS Group and 6 h for the Control Group. This finding is consistent with Gilani et al. [40], who showed that mechanical ventilation time was significantly less in Group I patients (IS): it was 5.49 + 2.28 h versus 6.74 + 5.46 h in Group II patients (control) (p value 0.05). This finding also agrees with Balandiuk and Kozlov [33], who reported that a significant decrease in the duration of MV in the IS group was 7.3 h compared to 10.4 h (p < 0.05) in the control group.

Moradian et al. [32] presented results that contradict the current study results. They revealed that there were no differences between the groups in mechanical ventilation time, with 10.5 h for the IS group and 11.5 h for the control group. Yazdemik et al. [29] also reported the same duration of mechanical ventilation in both groups following coronary artery bypass surgery, which means there were no differences between the groups. Moreover, Afrasiabi et al. [24] presented results that contradict the current study results. They found no differences in mechanical ventilation time between the study groups. Furthermore, Yánez-Brage et al. [12] in an observational study, showed that no statistical differences were observed during the time of mechanical ventilation between the study groups.

The current results showed significant differences between the incentive spirometry group and the control group in the numerical rating scale (NRS) pain scale with obvious pain in the IS group rather than control using the same analgesic plan as shown p value in all measurements at all times except at 12 h. To consider NRS, scores ≤ 5 correspond to mild, 6–7 to moderate, and ≥ 8 to severe pain. However, deep breathing exercises and cough may cause pain to patients, but patients well educated about incentive spirometer preoperative will be less needed to analgesia and better improvements in respiratory status. This finding is agreed with Renault et al. [9], who report that pain and postoperative fear are associated with changes in lung mechanics that affect the performance of periodic deep inspiration and effective cough with effective spirometry, allowing the accumulation of secretion, alveolar collapse, and changes in gas exchange, early incentive to cough decreases pain and better control.

The current study demonstrated the clinical application and IS a protocol that showed important results in reducing atelectasis occurrence in CABG patients. Meanwhile, some of the clinical trials question the effectiveness of IS use and why it is still prescribed to patients in different locations, especially after cardiac surgery [22, 25]. This paper suggests the implication of this protocol in intensive cardiac care units, especially with critical care nurses.

Proper preoperative incentive spirometry concurrent with deep breathing exercises and coughing every 4 h as a new protocol will enhance and improve the respiratory status, especially atelectasis with others improving in patient’s status that leads to a better outcome and less pain, however, patients covered with analgesics, but less use it.

This study was performed on patients who received invective spirometry for two days preoperative and did not have lung problems. Therefore, it is recommended to conduct a clinical study to examine incentive spirometry with deep breathing and cough trials in patients who will undergo CABG surgery with lung problems such as chronic obstructive pulmonary disease and asthma.