RESEARCH doi: 10.1111/nicc.12090
Effects of expiratory ribcage compression before endotracheal suctioning on arterial blood gases in patients receiving mechanical ventilation Mahmoud Kohan, Morteza Rezaei-Adaryani, Akram Najaf-Yarandi, Fatemeh Hoseini and Nahid Mohammad-Taheri ABSTRACT Aim and objectives: To investigate the effects of expiratory ribcage compression (ERCC) before endotracheal suctioning on the arterial blood gases (ABG) in patients receiving mechanical ventilation. Background: Endotracheal suctioning is one of the most frequently used methods for airway clearance in patients receiving mechanical ventilation. Chest physiotherapy techniques such as ERCC before endotracheal suctioning can be used as a means to facilitate mobilizing and removing airway secretions and improving alveolar ventilation. Design: A prospective, randomized, controlled cross-over design. Methods: A randomized controlled cross-over trial with a convenience sample of 70 mechanically ventilated patients was conducted from 2006 to 2007. The patients received endotracheal suctioning with (experiment-period) or without (control-period) an antecedent 5-min expiratory ribcage. All the patients experienced both periods with at least a 3-h washed-out interval between the two periods. ABG were measured 5 min before and 25 min after endotracheal suctioning. Results: The statistical tests showed that the levels of partial pressure of oxygen (PaO2 )/fraction of inspired oxygen (FiO2 ), partial pressure of carbon dioxide (PaCO2 ) and arterial oxygen saturation (SaO2 ) in the experimental period at 25 min after the intervention were significantly different from the control period. The tests also revealed that the levels of these variables at 25 min after suctioning were also significantly different from baseline values. However, these differences were clinically significant only for PaO2 /FiO2 . Conclusion: By improving the levels of PaO2 /FiO2 , ERCC can reduce the patients’ need for oxygen and hence it can at least reduce the side effects of oxygen therapy. Relevance to clinical practice: Improving PaO2 /FiO2 levels means less need for oxygen therapy. Hence, by applying ERCC we can at least minimize the side effects of oxygen therapy. Key words: Arterial blood gases • Critical care nursing • Endotracheal suctioning • Expiratory ribcage compression
BACKGROUND The major function of the respiratory system is gas exchange (Lewis et al., 2000; Berman et al., 2008; Black
& Hawks, 2009). For this function, a patent airway is necessary (Longo et al., 2012). Airway blockage due to accumulation of secretions can impair gas exchange
Authors: M Kohan, BSN, MSN, Lecturer, Department of Operating Room, Alborz University of Medical Sciences, Karaj, Iran; M Rezaei-Adaryani, BSN, MSN, PhD, Self-employed Persian-English Nurse Translator, Tehran, Iran; A Najaf-Yarandi, BSN, MSN, Lecturer, Department of Medical and Surgical Nursing, Iran University of Medical Sciences, Tehran, Iran; F Hoseini, BSc, MSc, Lecturer, Department of Biostatistics and Mathematics, Iran University of Medical Sciences, Tehran, Iran; N Mohammad-Taheri, BSN, Shahid Akbar-Abadi Teaching Hospital, Iran University of Medical Sciences, Tehran, Iran Address for correspondence: M Kohan, Lecturer, Department of Operating Room, Paramedical School, Alborz University of Medical Sciences, Karaj, Iran. E-mail: [email protected]
© 2014 British Association of Critical Care Nurses
1
Effects of expiratory ribcage compression
(Stone, 1992; Hari and Mackenzie, 2007) and hence, decrease partial pressure of oxygen (PaO2 ) and increase partial pressure of carbon dioxide (PaCO2 ) in arterial blood. Gas exchange impairment may result in dangerous complications such as acidosis, cyanosis and cardiac dysrhythmias (Potter and Perry, 2009). This problem is more severe in patients receiving mechanical ventilation (Stone, 1992), because the endotracheal tube irritates the mucus-producing goblet cells, resulting in increased mucus production. On the other hand endotracheal tubes damage cilia and impair ciliary function (Woodrow, 2000; Monahan et al., 2007). Moreover, intubated patients have impaired cough reflex. This is due to either the presence of the tube itself or the suppression of the cough reflex by sedation or analgesia (Adam and Osborne, 1997). Therefore, these patients lose the ability to cough and secretions tend to pool (Lewis et al., 2000; Moore and Woodrow, 2004; Black and Hawks, 2009). The accumulation of secretions will cause airway blockage leading to atelectasis and lung collapse (Adam and Osborne, 1997). Lung collapse is a common complication in patients receiving mechanical ventilation. It can lead to impaired oxygenation (Marini et al., 1979; Hari and Mackenzie, 2007) and increased length of hospital stay (Uzieblo et al., 2000). The mean of non-physician charges for hospital care in clients intubated for at least 48 h is about $12 000–$15 000. Costs for clients under mechanical ventilation can be four times more than the other clients in the intensive care unit who are not ventilated (Ignatavicius and Workman, 2002). Therefore, improving gas exchange by maintaining airway patency – aiming at reducing the time patients receive mechanical ventilation and decreasing health care costs – is one of the most important goals in the nursing care plan of the patients receiving mechanical ventilation. For achieving this goal, endotracheal suctioning and chest physiotherapy are two effective nursing interventions. Chest physiotherapy techniques before endotracheal suctioning are used to facilitate mobilization and removal of airway secretions as well as to improve alveolar ventilation (Smeltzer et al., 2010). A variety of chest physiotherapy techniques are widely used in patients receiving mechanical ventilation. One of these is expiratory ribcage compression (ERCC), which is well known as ‘squeezing’. This technique consists of manually compressing the ribcage during expiration and releasing the compression at the end of the expiration. This may mobilize and remove pulmonary secretions, facilitate active inspiration and improve alveolar ventilation (Miyagawa and Ishikawa, 1993; Takekawa, 2002). ERCC increases 2
forced expiratory volume (FEV) by about 30% and provides rest for the expiratory muscles. Respiratory demand is thus reduced and exhaustion averted. Moreover, it provides reassurance. Patients who have experienced it remained calm, whereas other chest physiotherapy techniques may cause distress (Watts, 1994). It is widely believed that in comparison with percussion or vibration, ribcage compression effectively treats and/or prevents lung collapse and that it is safer for critically ill patients (Miyagawa and Ishikawa, 1993; Miyagawa, 1995). However, there are few published studies regarding its effects (Unoki et al., 2004; Unoki et al., 2005).
THE STUDY Aim The aim of this study was to investigate the effects of ERCC before endotracheal suctioning on the arterial blood gases (ABG) in patients receiving mechanical ventilation.
Participants This randomized controlled trial was conducted between January 2006 and May 2007. During these 15 months, a convenience sample of patients was recruited from medical and surgical intensive care units and emergency department of a teaching hospital in Tehran, Iran. Patients, who were already under mechanical ventilation and were likely to require continuous invasive mechanical ventilation for more than 48 h and had an arterial cannula in place, were considered eligible for the study. The exclusion criteria included having rib fracture, chest trauma, hemodynamic instability, and chest tube, as well as ventilation with positive end expiratory pressure (PEEP). No changes in individual ventilator settings were made for the purpose of the study. Patients were excluded if their ventilator settings were changed during the study. Patients did not receive endotracheal suctioning within 1 h before each intervention. We estimated the sample size to detect a 40 mmHg PaO2 /FiO2 [the ratio of arterial PaO2 to the fraction of inspired oxygen (FiO2 )] difference between the two post-intervention data (based on the results of Unoki et al.’s study). Finally, with an alpha of 0·05 and a power of 0·80, we estimated that about 70 patients were needed.
Design In a prospective randomized controlled cross-over design, participants were randomly allocated (by using a table of random numbers) to alternatively receive either ERCC prior to endotracheal suctioning in the first © 2014 British Association of Critical Care Nurses
Effects of expiratory ribcage compression
Without Rib Cage Compression Session
With Rib Cage Compression Session
Blood Gas Analysis
Blood Gas Analysis
Blood Gas Analysis
Blood Gas Analysis 30 min
30 min
5 min 5 min Compression
> 3 hrs Endotracheal Suctioning
Endotracheal Suctioning
Figure 1 Study protocol. Each patient underwent endotracheal suctioning either with or without expiratory ribcage compression, in random order.
period, followed by endotracheal suctioning without ERCC in the second period (group A) or endotracheal suctioning without ERCC in the first period, followed by ERCC prior to endotracheal suctioning in the second period (group B; see Figure 1). On the basis of this crossover design, all 70 patients completed both periods. The period without ERCC was labelled as the ‘controlperiod’ and the period with ERCC was labelled as ‘experiment-period’. Each patient experienced these two periods on a same day, with at least a 3 h washedout interval. The patients were positioned so that the most affected lung region, as determined from a chest radiograph (atelectasis and/or infiltration) and/or crackles or rhonchi on auscultation, was uppermost. Radiograph interpretations were made by radiologists who were independent of the study. The patients were placed in the same position during each measurement period. Baseline measurements of ABG were made 5 min before endotracheal suctioning in both periods. In the experiment-period, after baseline measurement, patients received ERCC for 5 min followed by endotracheal suctioning. Post-intervention measurements of ABG were made 25 min after endotracheal suctioning with the same body position as decided before the first measurement. In the controlperiod, all of the above-mentioned interventions were performed but without ERCC (Figure 1).
Endotracheal suctioning Endotracheal suctioning was carried out with a 14 or 16 French in-line suction catheter, by one of two experienced intensive care nurses, according to the institutional standards. An in-line closed-suctioning system (TrachCare, Kimberly-Clark/Ballard Medical Products, Draper, Utah) was used for all patients. Patients did not receive endotracheal suctioning during 1 h before each intervention. © 2014 British Association of Critical Care Nurses
Expiratory ribcage compression The method of ERCC in this study was in accordance with the standard technique for clinical use (Miyagawa et al., 1993). Briefly, the operator uses both hands to gradually squeeze the ribcage during expiration. The operator attempted to give ERCC over the part of the ribcage that included the most affected lung region, from the end of inspiration to the end of expiration. Every ERCC was interrupted at the end of each expiratory phase to allow free inspiration in both spontaneously breathing and mechanically ventilated patients. Special care was taken to ensure that the compression was applied only during expiration. In patients undergoing volume controlled mode, ERCC was performed every two breaths. The operator attempted to synchronize compression rate with the patient’s individual respiratory rate. ERCC was performed by any of the two trained nurses – a female nurse for female patients and a male nurse for male patients. Initially, the lead researcher – the male nurse – learnt the procedure of ERCC from a physiotherapist. After acquiring complete mastery over performing the procedure – as confirmed by the physiotherapist – he invited a female critical care nurse and started to teach the ERCC, suctioning, arterial blood sampling and data collection procedures to her. The lead researcher and the female research assistant practiced the procedures together for 1 month. Thereafter, the physiotherapist was again to confirm female nurse’s mastery over performing the ERCC procedure.
Data collection We determined the patients’ characteristics through their medical records. These included the patients’ age, sex, weight, medical diagnosis and mechanical ventilation mode. Information about the patients’ 3
Effects of expiratory ribcage compression
ABG were also gathered which consisted of the following parameters: the ratio of arterial PaO2 to the FiO2 (PaO2 /FiO2 ), arterial PaCO2 , and arterial oxygen saturation (SaO2 ). PaO2 , PaCO2 and SaO2 were measured with a blood gas analyser (AVL 995, AVL List, Gaz, Austria). FiO2 was recorded from the ventilator monitor (Evita 2 Dura, Dr¨ager Medizintechnik, Lubeck, Germany). ¨
Ethical considerations The study was approved by the Ethics Committee of a regional university and also by the Ethics Committee of the study setting. As all the study participants had impaired levels of consciousness, the aim and process of the study were explained to their immediate relatives. They were assured of the confidentiality of their own and their patients’ personal information. They were also assured to be completely free whether to participate in, decline participation or leave the study. We also guaranteed that rejecting participation or withdrawing from the study never affect the course of treatment. Finally, written informed consent was obtained from them. The Ethics Committees had required us to clearly inform the patients’ attending physician of the aim and process of the study. Accordingly, a written informed consent was also obtained from the attending physicians.
Table 1 Characteristics of the study sample (n = 70) Age (mean ± SD years) Weight (mean ± SD years) Diagnosis (number and %) Intracerebral haemorrhage Subdural hematoma Subarachnoid haemorrhage Cerebrovascular accident Brain tumour Multiple trauma Pneumonia Sepsis Pulmonary tuberculosis Others Mechanical ventilation mode (number and %) Synchronized intermittent mandatory ventilation Spontaneous ventilation Pressure support ventilation
51·27 ± 15·83 75·84 ± 10·31 8 (11·4) 4 (5·7) 9 (12·9) 14 (20) 9 (12·9) 7 (10) 6 (8·6) 7 (10) 3 (4·3) 3 (4·3) 62 (88·6) 5 (7·1) 3 (4·3)
between two periods (period without ERCC or control, and period with ERCC) at baseline (i.e. 5 min before endotracheal suctioning; P = 0·127). However, the level of PaO2 /FiO2 at 25 min after endotracheal suctioning was significantly different between the control and ERCC periods (P < 0·0001). Additionally, the level of PaO2 /FiO2 at 25 min after suctioning in both periods was significantly different from the level of PaO2 /FiO2 at baseline (P < 0·0001, Table 2).
Data analysis Data were analysed using the software package SPSS version 11·5 (SPSS, Inc.). Analysis of cross-over designs is poorly described in the literature (Armitage and Hills, 1982; Prescott et al., 1998), therefore advice was obtained from a statistician. The paired-samples t-test and Wilcoxon signed-ranks test were used to compare the study parameters (PaO2 /FiO2 , PaCO2 and SaO2 ) before and after treatment. The level of statistical significance was set at less than 0·05 (P < 0·05).
Partial pressure of carbon dioxide The results of paired-samples t-test showed that the level of PaCO2 was significantly different between two periods at both baseline and at 25 min after endotracheal suctioning (P < 0·0001). Additionally, the level of PaCO2 at 25 min after suctioning in both periods was significantly different from the level of PaCO2 at baseline (P < 0·0001, Table 2).
Arterial oxygen saturation A total of 70 patients participated in this study (35 females, 35 males; patients’ age ranged from 18 to 70 years). Table 1 represents patient characteristics and ventilator settings. None of the patients had deleterious complications (e.g. drop in SaO2 , hemodynamic instability, tachypnea or barotrauma) related to ERCC.
The results of paired-samples t-test showed that the level of SaO2 both at baseline and at 25 min after endotracheal suctioning was significantly different between two periods (p-value for baseline and 25 min after suctioning were respectively equal to 0·03 and
Effects of expiratory ribcage compression before endotracheal suctioning on arterial blood gases in patients receiving mechanical ventilation Mahmoud Kohan, Morteza Rezaei-Adaryani, Akram Najaf-Yarandi, Fatemeh Hoseini and Nahid Mohammad-Taheri ABSTRACT Aim and objectives: To investigate the effects of expiratory ribcage compression (ERCC) before endotracheal suctioning on the arterial blood gases (ABG) in patients receiving mechanical ventilation. Background: Endotracheal suctioning is one of the most frequently used methods for airway clearance in patients receiving mechanical ventilation. Chest physiotherapy techniques such as ERCC before endotracheal suctioning can be used as a means to facilitate mobilizing and removing airway secretions and improving alveolar ventilation. Design: A prospective, randomized, controlled cross-over design. Methods: A randomized controlled cross-over trial with a convenience sample of 70 mechanically ventilated patients was conducted from 2006 to 2007. The patients received endotracheal suctioning with (experiment-period) or without (control-period) an antecedent 5-min expiratory ribcage. All the patients experienced both periods with at least a 3-h washed-out interval between the two periods. ABG were measured 5 min before and 25 min after endotracheal suctioning. Results: The statistical tests showed that the levels of partial pressure of oxygen (PaO2 )/fraction of inspired oxygen (FiO2 ), partial pressure of carbon dioxide (PaCO2 ) and arterial oxygen saturation (SaO2 ) in the experimental period at 25 min after the intervention were significantly different from the control period. The tests also revealed that the levels of these variables at 25 min after suctioning were also significantly different from baseline values. However, these differences were clinically significant only for PaO2 /FiO2 . Conclusion: By improving the levels of PaO2 /FiO2 , ERCC can reduce the patients’ need for oxygen and hence it can at least reduce the side effects of oxygen therapy. Relevance to clinical practice: Improving PaO2 /FiO2 levels means less need for oxygen therapy. Hence, by applying ERCC we can at least minimize the side effects of oxygen therapy. Key words: Arterial blood gases • Critical care nursing • Endotracheal suctioning • Expiratory ribcage compression
BACKGROUND The major function of the respiratory system is gas exchange (Lewis et al., 2000; Berman et al., 2008; Black
& Hawks, 2009). For this function, a patent airway is necessary (Longo et al., 2012). Airway blockage due to accumulation of secretions can impair gas exchange
Authors: M Kohan, BSN, MSN, Lecturer, Department of Operating Room, Alborz University of Medical Sciences, Karaj, Iran; M Rezaei-Adaryani, BSN, MSN, PhD, Self-employed Persian-English Nurse Translator, Tehran, Iran; A Najaf-Yarandi, BSN, MSN, Lecturer, Department of Medical and Surgical Nursing, Iran University of Medical Sciences, Tehran, Iran; F Hoseini, BSc, MSc, Lecturer, Department of Biostatistics and Mathematics, Iran University of Medical Sciences, Tehran, Iran; N Mohammad-Taheri, BSN, Shahid Akbar-Abadi Teaching Hospital, Iran University of Medical Sciences, Tehran, Iran Address for correspondence: M Kohan, Lecturer, Department of Operating Room, Paramedical School, Alborz University of Medical Sciences, Karaj, Iran. E-mail: [email protected]
© 2014 British Association of Critical Care Nurses
1
Effects of expiratory ribcage compression
(Stone, 1992; Hari and Mackenzie, 2007) and hence, decrease partial pressure of oxygen (PaO2 ) and increase partial pressure of carbon dioxide (PaCO2 ) in arterial blood. Gas exchange impairment may result in dangerous complications such as acidosis, cyanosis and cardiac dysrhythmias (Potter and Perry, 2009). This problem is more severe in patients receiving mechanical ventilation (Stone, 1992), because the endotracheal tube irritates the mucus-producing goblet cells, resulting in increased mucus production. On the other hand endotracheal tubes damage cilia and impair ciliary function (Woodrow, 2000; Monahan et al., 2007). Moreover, intubated patients have impaired cough reflex. This is due to either the presence of the tube itself or the suppression of the cough reflex by sedation or analgesia (Adam and Osborne, 1997). Therefore, these patients lose the ability to cough and secretions tend to pool (Lewis et al., 2000; Moore and Woodrow, 2004; Black and Hawks, 2009). The accumulation of secretions will cause airway blockage leading to atelectasis and lung collapse (Adam and Osborne, 1997). Lung collapse is a common complication in patients receiving mechanical ventilation. It can lead to impaired oxygenation (Marini et al., 1979; Hari and Mackenzie, 2007) and increased length of hospital stay (Uzieblo et al., 2000). The mean of non-physician charges for hospital care in clients intubated for at least 48 h is about $12 000–$15 000. Costs for clients under mechanical ventilation can be four times more than the other clients in the intensive care unit who are not ventilated (Ignatavicius and Workman, 2002). Therefore, improving gas exchange by maintaining airway patency – aiming at reducing the time patients receive mechanical ventilation and decreasing health care costs – is one of the most important goals in the nursing care plan of the patients receiving mechanical ventilation. For achieving this goal, endotracheal suctioning and chest physiotherapy are two effective nursing interventions. Chest physiotherapy techniques before endotracheal suctioning are used to facilitate mobilization and removal of airway secretions as well as to improve alveolar ventilation (Smeltzer et al., 2010). A variety of chest physiotherapy techniques are widely used in patients receiving mechanical ventilation. One of these is expiratory ribcage compression (ERCC), which is well known as ‘squeezing’. This technique consists of manually compressing the ribcage during expiration and releasing the compression at the end of the expiration. This may mobilize and remove pulmonary secretions, facilitate active inspiration and improve alveolar ventilation (Miyagawa and Ishikawa, 1993; Takekawa, 2002). ERCC increases 2
forced expiratory volume (FEV) by about 30% and provides rest for the expiratory muscles. Respiratory demand is thus reduced and exhaustion averted. Moreover, it provides reassurance. Patients who have experienced it remained calm, whereas other chest physiotherapy techniques may cause distress (Watts, 1994). It is widely believed that in comparison with percussion or vibration, ribcage compression effectively treats and/or prevents lung collapse and that it is safer for critically ill patients (Miyagawa and Ishikawa, 1993; Miyagawa, 1995). However, there are few published studies regarding its effects (Unoki et al., 2004; Unoki et al., 2005).
THE STUDY Aim The aim of this study was to investigate the effects of ERCC before endotracheal suctioning on the arterial blood gases (ABG) in patients receiving mechanical ventilation.
Participants This randomized controlled trial was conducted between January 2006 and May 2007. During these 15 months, a convenience sample of patients was recruited from medical and surgical intensive care units and emergency department of a teaching hospital in Tehran, Iran. Patients, who were already under mechanical ventilation and were likely to require continuous invasive mechanical ventilation for more than 48 h and had an arterial cannula in place, were considered eligible for the study. The exclusion criteria included having rib fracture, chest trauma, hemodynamic instability, and chest tube, as well as ventilation with positive end expiratory pressure (PEEP). No changes in individual ventilator settings were made for the purpose of the study. Patients were excluded if their ventilator settings were changed during the study. Patients did not receive endotracheal suctioning within 1 h before each intervention. We estimated the sample size to detect a 40 mmHg PaO2 /FiO2 [the ratio of arterial PaO2 to the fraction of inspired oxygen (FiO2 )] difference between the two post-intervention data (based on the results of Unoki et al.’s study). Finally, with an alpha of 0·05 and a power of 0·80, we estimated that about 70 patients were needed.
Design In a prospective randomized controlled cross-over design, participants were randomly allocated (by using a table of random numbers) to alternatively receive either ERCC prior to endotracheal suctioning in the first © 2014 British Association of Critical Care Nurses
Effects of expiratory ribcage compression
Without Rib Cage Compression Session
With Rib Cage Compression Session
Blood Gas Analysis
Blood Gas Analysis
Blood Gas Analysis
Blood Gas Analysis 30 min
30 min
5 min 5 min Compression
> 3 hrs Endotracheal Suctioning
Endotracheal Suctioning
Figure 1 Study protocol. Each patient underwent endotracheal suctioning either with or without expiratory ribcage compression, in random order.
period, followed by endotracheal suctioning without ERCC in the second period (group A) or endotracheal suctioning without ERCC in the first period, followed by ERCC prior to endotracheal suctioning in the second period (group B; see Figure 1). On the basis of this crossover design, all 70 patients completed both periods. The period without ERCC was labelled as the ‘controlperiod’ and the period with ERCC was labelled as ‘experiment-period’. Each patient experienced these two periods on a same day, with at least a 3 h washedout interval. The patients were positioned so that the most affected lung region, as determined from a chest radiograph (atelectasis and/or infiltration) and/or crackles or rhonchi on auscultation, was uppermost. Radiograph interpretations were made by radiologists who were independent of the study. The patients were placed in the same position during each measurement period. Baseline measurements of ABG were made 5 min before endotracheal suctioning in both periods. In the experiment-period, after baseline measurement, patients received ERCC for 5 min followed by endotracheal suctioning. Post-intervention measurements of ABG were made 25 min after endotracheal suctioning with the same body position as decided before the first measurement. In the controlperiod, all of the above-mentioned interventions were performed but without ERCC (Figure 1).
Endotracheal suctioning Endotracheal suctioning was carried out with a 14 or 16 French in-line suction catheter, by one of two experienced intensive care nurses, according to the institutional standards. An in-line closed-suctioning system (TrachCare, Kimberly-Clark/Ballard Medical Products, Draper, Utah) was used for all patients. Patients did not receive endotracheal suctioning during 1 h before each intervention. © 2014 British Association of Critical Care Nurses
Expiratory ribcage compression The method of ERCC in this study was in accordance with the standard technique for clinical use (Miyagawa et al., 1993). Briefly, the operator uses both hands to gradually squeeze the ribcage during expiration. The operator attempted to give ERCC over the part of the ribcage that included the most affected lung region, from the end of inspiration to the end of expiration. Every ERCC was interrupted at the end of each expiratory phase to allow free inspiration in both spontaneously breathing and mechanically ventilated patients. Special care was taken to ensure that the compression was applied only during expiration. In patients undergoing volume controlled mode, ERCC was performed every two breaths. The operator attempted to synchronize compression rate with the patient’s individual respiratory rate. ERCC was performed by any of the two trained nurses – a female nurse for female patients and a male nurse for male patients. Initially, the lead researcher – the male nurse – learnt the procedure of ERCC from a physiotherapist. After acquiring complete mastery over performing the procedure – as confirmed by the physiotherapist – he invited a female critical care nurse and started to teach the ERCC, suctioning, arterial blood sampling and data collection procedures to her. The lead researcher and the female research assistant practiced the procedures together for 1 month. Thereafter, the physiotherapist was again to confirm female nurse’s mastery over performing the ERCC procedure.
Data collection We determined the patients’ characteristics through their medical records. These included the patients’ age, sex, weight, medical diagnosis and mechanical ventilation mode. Information about the patients’ 3
Effects of expiratory ribcage compression
ABG were also gathered which consisted of the following parameters: the ratio of arterial PaO2 to the FiO2 (PaO2 /FiO2 ), arterial PaCO2 , and arterial oxygen saturation (SaO2 ). PaO2 , PaCO2 and SaO2 were measured with a blood gas analyser (AVL 995, AVL List, Gaz, Austria). FiO2 was recorded from the ventilator monitor (Evita 2 Dura, Dr¨ager Medizintechnik, Lubeck, Germany). ¨
Ethical considerations The study was approved by the Ethics Committee of a regional university and also by the Ethics Committee of the study setting. As all the study participants had impaired levels of consciousness, the aim and process of the study were explained to their immediate relatives. They were assured of the confidentiality of their own and their patients’ personal information. They were also assured to be completely free whether to participate in, decline participation or leave the study. We also guaranteed that rejecting participation or withdrawing from the study never affect the course of treatment. Finally, written informed consent was obtained from them. The Ethics Committees had required us to clearly inform the patients’ attending physician of the aim and process of the study. Accordingly, a written informed consent was also obtained from the attending physicians.
Table 1 Characteristics of the study sample (n = 70) Age (mean ± SD years) Weight (mean ± SD years) Diagnosis (number and %) Intracerebral haemorrhage Subdural hematoma Subarachnoid haemorrhage Cerebrovascular accident Brain tumour Multiple trauma Pneumonia Sepsis Pulmonary tuberculosis Others Mechanical ventilation mode (number and %) Synchronized intermittent mandatory ventilation Spontaneous ventilation Pressure support ventilation
51·27 ± 15·83 75·84 ± 10·31 8 (11·4) 4 (5·7) 9 (12·9) 14 (20) 9 (12·9) 7 (10) 6 (8·6) 7 (10) 3 (4·3) 3 (4·3) 62 (88·6) 5 (7·1) 3 (4·3)
between two periods (period without ERCC or control, and period with ERCC) at baseline (i.e. 5 min before endotracheal suctioning; P = 0·127). However, the level of PaO2 /FiO2 at 25 min after endotracheal suctioning was significantly different between the control and ERCC periods (P < 0·0001). Additionally, the level of PaO2 /FiO2 at 25 min after suctioning in both periods was significantly different from the level of PaO2 /FiO2 at baseline (P < 0·0001, Table 2).
Data analysis Data were analysed using the software package SPSS version 11·5 (SPSS, Inc.). Analysis of cross-over designs is poorly described in the literature (Armitage and Hills, 1982; Prescott et al., 1998), therefore advice was obtained from a statistician. The paired-samples t-test and Wilcoxon signed-ranks test were used to compare the study parameters (PaO2 /FiO2 , PaCO2 and SaO2 ) before and after treatment. The level of statistical significance was set at less than 0·05 (P < 0·05).
Partial pressure of carbon dioxide The results of paired-samples t-test showed that the level of PaCO2 was significantly different between two periods at both baseline and at 25 min after endotracheal suctioning (P < 0·0001). Additionally, the level of PaCO2 at 25 min after suctioning in both periods was significantly different from the level of PaCO2 at baseline (P < 0·0001, Table 2).
Arterial oxygen saturation A total of 70 patients participated in this study (35 females, 35 males; patients’ age ranged from 18 to 70 years). Table 1 represents patient characteristics and ventilator settings. None of the patients had deleterious complications (e.g. drop in SaO2 , hemodynamic instability, tachypnea or barotrauma) related to ERCC.
The results of paired-samples t-test showed that the level of SaO2 both at baseline and at 25 min after endotracheal suctioning was significantly different between two periods (p-value for baseline and 25 min after suctioning were respectively equal to 0·03 and
