Endotracheal suctioning of the adult intubated patient—What is the evidence?

Intensive and Critical Care Nursing (2009) 25, 21—30 available at www.sciencedirect.com journal homepage: www.elsevier.com/iccn REVIEW Endotracheal suctioning of the adult intubated patient—–What is the evidence? Carsten M. Pedersen a, Mette Rosendahl-Nielsen b, Jeanette Hjermind c, Ingrid Egerod d,∗ a Intensive Care Unit, Frederiksberg Hospital, DK, Denmark Intensive Care Unit, Rigshospitalet, DK, Denmark c Bispebjerg Hospital, DK, Denmark d The University Hospitals Centre for Nursing and Care Research, Rigshospitalet, Department 7331, Blegdamsvej 9, DK-2100 Copenhagen O, Denmark b Accepted 28 May 2008 KEYWORDS Endotracheal suctioning; Evidence-based practice; Intensive care; Nursing; Suction Summary Intubated patients may be unable to adequately cough up secretions. Endotracheal suctioning is therefore important in order to reduce the risk of consolidation and atelectasis that may lead to inadequate ventilation. The suction procedure is associated with complications and risks including bleeding, infection, atelectasis, hypoxemia, cardiovascular instability, elevated intracranial pressure, and may also cause lesions in the tracheal mucosa. The aim of this article was to review the available literature regarding endotracheal suctioning of adult intubated intensive care patients and to provide evidence-based recommendations The major recommendations are suctioning only when necessary, using a suction catheter occluding less than half the lumen of the endotracheal tube, using the lowest possible suction pressure, inserting the catheter no further than carina, suctioning no longer than 15 s, performing continuous rather than intermittent suctioning, avoiding saline lavage, providing hyperoxygenation before and after the suction procedure, providing hyperinflation combined with hyperoxygenation on a non-routine basis, always using aseptic technique, and using either closed or open suction systems. © 2008 Elsevier Ltd. All rights reserved. Introduction Intubated patients may be unable to adequately cough up secretions. Based on the work by Day et al. (2002), endotra- Corresponding author. Tel.: +45 35457365; fax: +45 35457399. E-mail addresses: carstenmp@hotmail.com (C.M. Pedersen), mette.rosendahl@get2net.dk (M. Rosendahl-Nielsen), jh46@bbh.regionh.dk (J. Hjermind), ie@ucsf.dk (I. Egerod). ∗ cheal suctioning (ET suctioning) is an important activity in reducing the risk of consolidation and atelectasis that may lead to inadequate ventilation. ET suctioning is defined as: ‘‘A component of bronchial hygiene therapy and mechanical ventilation and involves the mechanical aspiration of pulmonary secretions from a patient with an artificial airway in place’’ (AARC, 1993 p. 500). The procedure is associated with complications and risks including bleeding, infection, atelectasis, hypoxemia, cardiovascular instability, elevated intracranial pressure, and may also cause lesions in the 0964-3397/$ — see front matter © 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.iccn.2008.05.004 22 tracheal mucosa (Branson et al., 1993; Thomson et al., 2000). Endotracheal suctioning is described by patients as painful and uncomfortable, and may result in a choking sensation initiating a violent cough, and also cause an unpleasant sensation that the lungs are actually being suctioned into the catheter (Gjengedal, 1994; Patak et al., 2004). Despite the discomfort, patients report that the procedure is necessary and subsequently eases their breathing (Bergbom-Engberg, 1989; Jablonski, 1994). The discomfort associated with suctioning does not diminish during a course of mechanical ventilation; on the contrary, it may worsen (Bergbom-Engberg, 1989). The apparent discomfort and the potential complications of suctioning may intimidate inexperienced nurses. As Day et al. (2002) stated practice is not always based on current research recommendations, which may lead to inconsistent practice among nurses, affecting the patient experience (Sole et al., 2003; Celik and Elbas, 2000). Due to the frequency and risk associated with endotracheal suctioning, there is a need to examine clinical practice critically, and to identify clinical research to guide practice. The aim of this article was to review the available literature regarding the endotracheal suctioning of adult intubated intensive care patients and to provide evidence-based recommendations. Methods Design A search of literature was performed in Medline, Cinahl and Cochrane Library. The following key words were used: intensive care, critical care, suction, endotracheal suctioning. The initial strategy was to use broad terms in order to increase the sensitivity of the search. The search was then limited to adult patients (≥19 years old) including Danish, Swedish, Norwegian and English language articles from 1995 to 2008. References cited in bibliographies of past reports were included. In order to retrieve the primary source for some of the widely accepted recommendations, it was necessary to include articles and studies dating back to 1962. In order to examine the patient perspective, qualitative research on patient’s experiences during ventilator treatment was included, but very few data were retrieved. Studies involving elevated intracranial pressure (ICP) were excluded, because ICP monitoring requires a specialised protocol. A total of 77 papers were included in the final review, 4 studies describing patient experiences of suctioning, 19 literature reviews, 2 meta-analyses and 52 clinical trials. Data analysis Papers were categorised and reviewed according to the following subjects: ET suctioning performed as a routine or when necessary (prn), appropriate catheter size, suction pressure, depth of insertion, duration of procedure, intermittent or continuous suction pressure, pre-oxygenation, hyperinflation (bagging), instillation of normal saline, hygiene guidelines, and open versus closed endotracheal suction systems. These themes were chosen based on clini- C.M. Pedersen et al. Figure 1 Literature appraisal instrument. cal practice and are all essential in preventing or minimising physiological complications associated with endotracheal suctioning. The literature was reviewed using an appraisal instrument (Fig. 1). The studies were reviewed critically, to establish the current best research evidence to recommend a specific procedure (Sackett et al., 1996). The current best research evidence was defined as patient centred research into the efficacy and safety of treatment and care, in which new evidence invalidates previously accepted regimens and replaces them with new ones. The evidence included quantitative as well as qualitative studies that were judged by how well the study question related to the research method, and the consistency of results, discussion and conclusion (Rolfe, 1999; Rycroft-Malone et al., 2004). The focus of this review was on the knowledge base of the recommendations rather than the level of evidence refering exclusively to the bio-medical research hierarchy. Results Suctioning performed routinely or when necessary Traditionally, endotracheal suctioning was performed routinely every 1—2 h to ensure the removal of secretions, and to prevent pneumonia and endotracheal tube (ET-tube) occlusion (Glass and Grap, 1995). Due to the considerable risk and adverse effects, it is now recommended, that ET suctioning should be performed only when necessary (Young, 1984; Branson et al., 1993; Odell et al., 1993; Glass and Grap, 1995; Day et al., 2002). A prospective randomised study of 383 patients demonstrated that prn suctioning was associated with fewer adverse effects. There was no significant variation in ICU mortality, incidence of pulmonary infections, duration of intubation, or ICU-stay in patients that were suctioned routinely or only when necessary (Van de Leur et al., 2003a,b). A study including 14 patients, showed no significant variation in complications (i.e. decreased saturation, increased airway pressure, changes in heart rate, heart rhythm and Endotracheal suctioning of the adult intubated patient mean arterial pressure (MAP), ET-tube occlusion and infection rate) between routine and prn suctioning (Wood, 1998a). The clinical implications of this study were limited, due to a small sample size, and similar suction frequency in the two groups studied. Suctioning only when necessary requires the nurse to be able to determine the patient’s need for suctioning. Indications for suctioning are cough, visible or audible secretions, coarse or absent respiratory sounds, increased airway pressure, desaturation, or increased respiratory work (Wood, 1998b). A clinical study including 66 patients has shown that the risk of overlooking residual secretions decreased when the assessment was done using a stethoscope. Retained secretions were best identified from the appearance of a saw-tooth pattern on the flow-volume loop, on the monitor screen of the ventilator (Guglielminotti et al., 2000). Flow-volume loops are ventilator graphics that provide information on leaks and resistance. The clinical relevance of the study is uncertain as retained secretions were defined as >0.5 ml obtained on subsequent suctioning. However, this study indicates that clinical assessment can be inadequate, and nurses may not have the necessary skills to carry out the assessment (Wood, 1998a). A number of studies show that the internal lumen of endotracheal tubes decreases significantly after a few days of intubation, sometimes only after 8 h, due to formation of biofilm and the adherence of secretions on the surface (Tenaillon, 1990; Glass et al., 1999; Shah and Kollef, 2004; Chirag and Kollef, 2004). A minimum frequency of ET suctioning should be considered due to the risk of not detecting retained secretions and partial tube occlusion, as long as the patient is unable to adequately clear the secretions. What is the recommendation on routine versus ‘‘prn suctioning’’? Based on clinical experience and a number of studies, it is recommended that endotracheal suctioning should be performed only when necessary. There is no evidence to support maximum suction intervals, but it may be advisable to perform suctioning at least every 8 h to reduce the risk of partial occlusion of the ET-tube and the accumulation of secretions. Auscultation is recommended as part of clinical assessment. Appropriate catheter size There is consensus in the literature that suction catheters should be as small as possible, yet large enough to facilitate secretion removal. When the catheter size is small, air may enter the lungs around the catheter during suctioning. This prevents a sudden drop in functional residual capacity Figure 2 23 (FRC), and thus reduces the risk of atelectasis (Glass and Grap, 1995; Wood, 1998b). One study suggests that nurses may choose larger catheters than recommended and necessary (Day et al., 2001). This could be due to experience, habit, lack of evidence, or the convention that a larger catheter may be necessary in the case of thick secretions (Wood, 1998b). It is generally recommended that the maximum external diameter of the suction catheter should be half the size of the internal diameter of the ET-tube (Demers and Saklad, 1973; Branson et al., 1993; McKelvie, 1998; Odell et al., 1993; Glass and Grap, 1995; Wood, 1998b; Day et al., 2002). This recommendation can be traced to a single paper, in which it is demonstrated by a mathematical model, that a larger catheter increases the negative pressure applied on the lungs (Rosen and Hillard, 1962). There is, however, no evidence to support this exact ratio. It is also stated that the effectiveness of the suction catheter depends on the size; the larger the catheter, the greater the effectiveness of secretion removal. The widely accepted formula for calculating catheter size is: Suction catheter size [Fr] = (ET-tube size [mm] − 2) × 2. Since the lumen of the ET-tube is calculated as:  × r2 × length, a doubling of the diameter of the ET-tube leads to a quadrupling of the tube lumen. Thus, it would be more logical to recommend that the suction catheter should occlude less than half the internal lumen, rather than half the diameter of the ET-tube. A lung model test supports this, as it shows that when a suction catheter occludes less than half the lumen of the ET-tube, the negative pressure in the lungs is minimised, because the space in the tube that allows air to pass to the lungs during suctioning correlates to the tube lumen (Tiffin et al., 1990). According to this, the following formula for calculating catheter size is suggested: Suction catheter size [Fr] = (ET-tube size [mm] − 1) × 2 (see Fig. 2). This formula may be controversial, as it leads to a slightly larger catheter size than generally recommended, but it is perhaps more efficient for the removal of thick secretions. What is the recommendation on suction catheter size? Based on clinical experience, calculation of ET-tube lumen and a lung model test, it is recommended that the suction catheter should occlude less than half of the internal lumen of the endotracheal tube. Level of suction pressure A number of studies recommend the use of the lowest possible suction pressure to reduce the risk of atelectasis, hypoxia and damage to the tracheal mucosa (Branson Calculation of suction catheter lumen size. 24 et al., 1993; Glass and Grap, 1995; Wood, 1998a,b; Day et al., 2002). At the same time suction pressure must be sufficient to clear the secretions. The recommendation of maximum suction pressure is exclusively based on experience; no clinical studies support an exact limit. A meta-analysis demonstrates that a suction pressure of 80—120 mmHg was used in more than 50% of the studies of endotracheal suctioning examined (Oh and Seo, 2003). The negative pressure that is actually applied to the lungs during suctioning cannot be reliably assessed on the manometer dial of the suctioning equipment; it depends on the suction catheter-ET-tube ratio, the duration of the procedure, and the volume and viscosity of the secretions (Rosen and Hillard, 1962). One study has shown that there was no difference in induced tracheobroncheal lesions using negative pressure of 145 mmHg versus 500 mmHg, when the suction catheter occludes less than half the internal lumen of the endotracheal tube. One study on dogs has demonstrated any application of negative pressure with endotracheal suction produces significant damage to tracheal tissue (Czarnik et al., 1991). It is concluded that the degree of negative pressure applied to the lungs depends on catheter size and duration of suctioning. As high pressure is more effective in removing secretions, a pressure of 200—300 mmHg may be applied when using the appropriate catheter size (Tenaillon, 1990). What is the recommendation on suction pressure? Based on clinical experience, it is recommended using the lowest possible suction pressure during endotracheal suctioning, usually 80—120 mmHg. A negative pressure of 200 mmHg may be applied provided that the appropriate suction catheter size is used. Depth of catheter insertion A number of papers recommend that the suction catheter should be inserted to the carina and retracted 1—2 cm before applying suction (Wood, 1998b; Celik and Elbas, 2000; Day et al., 2002). A single study supports this practice as there is no difference in duration of intubation, ICU-stay, or mortality using minimally invasive suctioning in which the suction catheter is inserted to the length of the ET-tube only, or deep endotracheal suctioning. The minimally invasive procedure is associated with fewer adverse effects, but this is not exclusively related to the suction depth. It is indicated that deep suctioning may be necessary in patients with large amounts of secretions in the lower airways (Van de Leur et al., 2003a,b). In ETS, secretions are removed only from the central airways. The movement of secretions depends upon mucociliary clearance, level of sedation, and the patient’s ability to cough. Deep endotracheal suctioning may cause a greater negative pressure applied to the lungs, due to occlusion of more than half the lumen of the bronchial branch (Rosen and Hillard, 1962). This may lead to bradycardia (Day et al., 2002). C.M. Pedersen et al. which the suction catheter is inserted to the length of the ETtube only. The suction catheter is inserted to the carina and then retracted 1—2 cm before suctioning is performed, or the length of the suction catheter is estimated by measuring an identical endotracheal tube. Duration of suctioning procedure The duration of the suctioning procedure affects the severity of adverse effects. It may be difficult to determine exactly which complications can be attributed to the duration of suctioning. The maximum duration of suctioning is inadequately documented. One study has shown that the correct catheter size and duration of less than 15 s reduced the drop in FRC and PaO2 (partial pressure of oxygen) (Tenaillon, 1990). A clinical trial conducted on dogs has shown that the reduction of PaO2 increases after 5 s of suctioning (George, 1983). In a comparative study of complications associated with suctioning, a maximum of 10 s is recommended for the suctioning itself and 15 s for the entire procedure (Celik and Elbas, 2000; Wood, 1998b; Day et al., 2002). Suction should not be applied during catheter insertion. What is the recommendation on the duration of the suction procedure? Based on clinical experience, it is recommended that the suctioning procedure should last no longer than 15 s. Intermittent suctioning technique The argument in favour of using intermittent suctioning is that it minimises inward folding (invagination) of the tracheal mucosal membrane into the suction catheter. There are no clinical studies supporting this argument, or studies that show a difference in complications between intermittent and continuous suctioning. The literature does not provide an answer to which should be applied in the individual suctioning procedure (Wood, 1998b; Glass and Grap, 1995). If the suction catheter is inserted no further than 2 cm above the carina, the risk of invagination is assumed to be minimal. One study has shown that continuous as well as intermittent application of negative pressure with endotracheal suction produces significant damage to tracheal tissue on dogs (Czarnik et al., 1991). When the closed suctioning system is used, risk of alveolar collapse increases with the use of intermittent suctioning (Stenqvist et al., 2001). What is the recommendation on intermittent versus continuous suctioning? Based on clinical experience and a single study, the recommendation is continuous rather than intermittent suctioning during the individual suction procedure. Saline lavage prior to endotracheal suctioning What is the recommendation on catheter insertion depth? Based on clinical experience and a single study, it is recommended using minimally invasive endotracheal suctioning in Conventional wisdom has it that saline lavage prior to endotracheal suctioning eases catheter insertion, induces cough, facilitates secretion removal, and ultimately improves the Endotracheal suctioning of the adult intubated patient patient’s oxygenation. The procedure is conducted by injecting 2—5 ml sterile normal saline into the ET-tube prior to suctioning (Wood, 1998b; Blackwood, 1999; Celik and Kanan, 2006). A number of studies have advised against routine use of normal saline instillation (Odell et al., 1993; McKelvie, 1998; Wood, 1998b; Blackwood, 1999; Day et al., 2002; Celik and Kanan, 2006). Most studies have been unable to document that normal saline increases aspiration of secretions (Demers and Saklad, 1973; Bostick and Wendelgass, 1987; Ackerman, 1993), while a few studies have suggested a positive effect on the amount of secretions obtained after the instillation of normal saline (Reynolds et al., 1990; Isea et al., 1993). Several studies argue against routine instillation of normal saline because saline fails to dilute tenacious secretions and lubricate the tube (Odell et al., 1993; Wood, 1998b; McKelvie, 1998; Blackwood, 1999; Day et al., 2002). Studies of the effect of normal saline instillation on patient’s vital signs show no significant reduction in minute volume, airway pressure, pulse and blood pressure (Bostick and Wendelgass, 1987; Gray et al., 1990; Reynolds et al., 1990; Ackerman, 1993; Akgul and Akyolcu, 2002; Celik and Kanan, 2006). Some studies show that normal saline does not affect oxygen saturation, while others show reduced saturation for as much as five minutes post suctioning (Ackerman, 1993; Kinloch, 1999; Akgul and Akyolcu, 2002). Instillation of normal saline prior to suctioning may dislodge bacteria from the biofilm inside the endotracheal tube. A study performed on used ET-tubes shows that bacterial release is greater with saline lavage than the insertion of the suction catheter (Hagler and Traver, 1994). Whether this increases the infection rate in intubated patients is uncertain, but a study by Hanley et al. (1978) documents that only 18.7% of the saline is regained during suctioning. Patient discomfort during suctioning is considerable, but the discomfort is not affected by the instillation of normal saline (Jablonski, 1994; O’Neal et al., 2001). One small study suggested that the sensation of dyspnoea increased in older patients after instillation of normal saline (O’Neal et al., 2001). What is the recommendation on saline lavage? Based on clinical studies, routine instillation of normal saline prior to endotracheal suctioning is not recommended. No reliable positive effects in terms of secretion removal, saturation, or ventilation have been demonstrated. The only reliable effect of the procedure is cough stimulation, but due to the increased risk of infections and patient discomfort, this should not be an indication. Hyperoxygenation prior to endotracheal suctioning Hyperoxygenation is performed by increasing the intake of oxygen immediately prior to suctioning (3—6 ventilations), and when appropriate, after endotracheal suctioning. Preoxygenation is performed to minimise hypoxaemia and related complications induced by suctioning (Branson et al., 1993; Thomson et al., 2000). It is concluded in meta-analysis that pre-oxygenation with 100% oxygen, reduces the occurrence of suction-induced hypoxaemia by 32%. Combining pre 25 and post-oxygenation, reduced the occurrence of hypoxia by 49%. Compared with no intervention, the combination of hyperoxygenation and hyperinflation reduced the occurrence of hypoxemia by 55% (Oh and Seo, 2003). The most frequently used oxygen setting when performing pre-oxygenation is FiO2 of 1.00. Ventilation with 100% oxygen for longer periods of time may lead to absorption atelectasis, and thus reduce pulmonary volume. In a study of short-term hyperoxygenation, this adverse effect was not evident (Fernandez et al., 2004). A clinical trial of patients with chronic obstructive pulmonary disease (COPD) showed that pre-oxygenation with 20% above the baseline FiO2 , was sufficient to prevent hypoxemia (Rogge et al., 1989). The study did not provide adequate documentation for recommending pre-oxygenation with 20% above baseline FiO2 due to small sample size. What is the recommendation on hyperoxygenation prior to suctioning? Based on clinical controlled trials, pre-oxygenation by the delivery of 100% oxygen for at least 30 s prior to and after the suctioning procedure is recommended to prevent decrease in oxygen saturation. Hyperinflation (manual/mechanical) prior to endotracheal suctioning Hyperinflation is performed by inflating the patient’s lungs, manually with a ventilation bag (bagging), or via the mechanical ventilator. A volume of 1.5× baseline tidal volume is the most common for hyperinflation prior to suctioning. The procedure is assumed to improve the patient’s oxygenation capacity by recruiting pulmonary volume and loosening secretions (Day et al., 2002). Hyperinflation is associated with the risk of barotrauma, cardiovascular instability and increased intracranial pressure (Day et al., 2002). The effects of hyperinflation are usually studied in combination with hyperoxygenation. In a meta-analysis of interventions to prevent suction-induced hypoxemia, it was found that the combination of hyperoxygenation and hyperinflation reduced the occurrence of hypoxemia by 55% compared to no intervention (Oh and Seo, 2003). As the effect of short-term hyperoxygenation is significantly positive in adult patients, it is difficult to differentiate the effect of hyperinflation. In one study the interventions hyperoxygenation, hyperinflation, or a combination of the two were compared. Hyperinflation alone caused a decrease in oxygen saturation, while the most positive effect on saturation was found, when hyperinflation was used in combination with hyperoxygenation. Some of the patients experienced dyspnoea when hyperinflated (Lookinland and Appel, 1991). In addition, patients also report increased discomfort during manual ventilation compared with mechanical ventilation (Jablonski, 1994). The use of pulmonary recruitment immediately after open endotracheal suctioning resulted in earlier return to baseline values for pulmonary volume and oxygen saturation, in a single study. Pulmonary recruitment was performed on patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), by applying an inspiration pressure of 45 cm H2 O to the lungs for 20 s (Dyhr 26 et al., 2003). This procedure is not comparable with traditional hyperinflation, but similar results from recruitment, were found in other studies (Almgren, 2005; Maggiore et al., 2003). Nurses perform manual ventilation with considerable individual variation. Manual ventilation with insufficient tidal volume and a peak airway pressure of up to 96 cm H2 O were performed (Clapham et al., 1995; Robson, 1998). In a study of 100 nurses performing manual hyperinflation by a ventilation bag, it was shown that only one-third were able to deliver a tidal volume greater than the one delivered by the ventilator. The mean volume delivered was 17% lower during manual ventilation, and some patients were hypo-ventilated compared with the volume delivered by the ventilator (Glass et al., 1993). It should be noted that hyperinflation prior to suctioning and pulmonary recruitment are different procedures. What is the recommendation on hyperinflation prior to suctioning? Based on clinical controlled trials, hyperinflation combined with hyperoxygenation prior to suctioning is recommended on a non-routine basis, as it prevents the decrease in oxygen saturation. Hyperinflation used alone results in a larger decrease in oxygen saturation. Hyperinflation should be delivered by the ventilator, in order to control tidal volume and inspiration peak pressure. Routine use of hyperinflation is not recommended due to the risk of barotrauma from large volumes, high peak pressures and patient discomfort. Recruitment manoeuvres following endotracheal suctioning in patients with ALI and ARDS is recommended by individual order only. Hygiene guidelines for open endotracheal suctioning system Ventilator-treated patients are at high risk of acquiring nosocomial infections, which increase mortality and morbidity, ICU-stay, and costs. Intubation and ET suctioning impede the effect of normal defence mechanisms (Khatib et al., 1999; Combes et al., 2000). It is highly recommended to maintain aseptic technique, including hand washing and use of gloves, because ET suctioning is an invasive procedure that may lead to contamination of the lower airways (Thomson et al., 2000; Day et al., 2002). When using an open suction system, a new sterile disposable suction catheter for every insertion in the tube is widely recommended (Day et al., 2002; Celik and Elbas, 2000). In a single clinical controlled trial, no significant difference in infection rate from reuse of the suction catheter for 24 h in the same patient was shown (Scoble et al., 2001). The clinical relevance of the study can be questioned, as the risk of contamination of the surroundings is considerable when the suction catheter is handled and stored between suctioning procedures. After suctioning, the catheter is discarded and the suction hose is flushed with tap water from a canister. It is recommended to change the canister every 8 h (Statens Serum Institut, 2001). When ET suctioning is performed with an open suction system, there is considerable risk of contaminating the hands of the staff. To protect reciprocal contamination between patient and staff, it is widely recommended to use dispos- C.M. Pedersen et al. able gloves as standard precaution (Danish Standards, 2001; DoH, 2007). Aseptic technique is also necessary when using closed suction systems because condensation from the suction system may splash on the staff (Blackwood and Webb, 1998). According to universal precautions the eyes should be protected by goggles whenever splashing is a possibility, but no suction guidelines include goggles as standard procedure. What is the recommendation on infection control in relation to suctioning? Based on increased risk of infection, the use of aseptic technique is recommended. When using open suction system, a sterile suction catheter must be used, for each insertion in the endotracheal tube. To protect the staff, gloves should be used with both open and closed suction systems. Hand washing should always be carried out before and after the procedure. Closed versus open suction systems The ‘‘closed suction system’’ (CSS) consists of a reusable sterile suction catheter protected by a transparent sleeve that prevents contact between the catheter and the environment. CSS is connected to the ET-tube as an integrated part of the mechanical ventilator system and allows ET suctioning without disconnecting the ventilator, which minimises the decrease in pulmonary volume caused by disconnection of the positive end-expiratory pressure (PEEP). Closed suction systems have been regarded as less effective for secretion removal than ‘‘open suction systems’’ (OSS) (Johnson et al., 1994; Blackwood, 1998). A single study supports this assumption, although the suction system used is only a semi-closed system, where suctioning is performed via the swivel-adapter (Lascoki et al., 2006). In another study there was no significant difference in the amount of secretions removed with CSS compared with OSS (Witmer et al., 1991). A bench test showed that the quantity of secretions removed with CSS was significantly lower than with OSS, when using same catheter size and suction pressure, as the high inspiratory flow from the ventilator ‘‘pushes’’ the secretions away from the suction catheter and further down the lungs (Lindgren et al., 2004). Some clinical trials conducted on patients with ALI show that the use of closed systems minimises the loss of pulmonary volume in volume-controlled ventilated patients. The decrease in pulmonary volume and oxygen saturation was significantly greater with CSS than OSS. As the loss of pulmonary volume is critical in patients with ALI, CSS is recommended in patients with impaired oxygenation and risk of alveolar collapse (Johnson et al., 1994; Cereda et al., 2001; Maggiore et al., 2003). Another clinical trial conducted on patients with mild to moderate lung injury showed the same effect on pulmonary volume when suctioning was performed via the swivel-adapter (semi-closed system) and when CSS was used (Fernandez et al., 2004). No difference in suction-induced saturation decrease was demonstrated between CSS and OSS in a clinical trial conducted on pigs on pressure control (Almgren et al., 2004). Endotracheal suctioning of the adult intubated patient In two clinical trials CSS was shown to minimise hypertension and arrhythmias induced by endotracheal suctioning. OSS and CSS resulted in an increase in heart rate, but 30 s after OSS suctioning patients had significantly lower heart rate compared to CSS (Cereda et al., 2001; Johnson et al., 1994). A test performed on a lung model demonstrates that CSS used with volume-controlled ventilation resulted in extreme negative airway pressure if the suction flow exceeded the flow output of the ventilator. An increase in auto-PEEP was found, due to resistance to expiration when the suction catheter was inserted in the endotracheal tube. Based on this, CSS in connection with volume-controlled and pressureregulated control modes is not recommended (Stenqvist et al., 2001). A number of papers discuss the risk of ventilatorassociated pneumonia (VAP) with CSS (Day et al., 2002). Two trials demonstrated increased bacterial colonization, but an increased incidence of VAP was not shown (Deppe et al., 1990; Topeli et al., 2004). Other controlled trials show that in terms of VAP, there is no significant difference between the two suction systems (Johnson et al., 1994; Kollef et al., 1997; Combes et al., 2000; Zeitoun et al., 2003; Lorente et al., 2005). The findings are supported by an evidence-based guideline on VAP, and a meta-analysis (Dodek et al., 2004; Jongerden et al., 2007). In a small clinical controlled trial, it was demonstrated that the incidence of lung to stomach contamination was more frequent with OSS than with CSS. Five cases of VAP were reported with OSS, and none with CSS (Rabitsch et al., 2004). One non-randomised crossover study deals with environmental bacterial contamination after ET suctioning. In OSS bacterial contamination could not be detected for either OSS or CSS in a radius of 3 m from the ET-tube (Cobley et al., 1991). It is argued that the use of a CSS reduces the exposure of the staff to contamination from the patient’s airways (Cobley et al., 1991; Freytag et al., 2003). Increased bacterial growth may be the result if CSS are not completely cleaned between suctions (Blackwood and Webb, 1998). It is shown in a single clinical trial, that within 24 h of use, microbiological growth (bacteria/yeast) is detectable in 89% of CSS, and increased with longer term use (Freytag et al., 2003). Clinical controlled trials conclude, however, that the frequency of VAP does not increase, even if the same suction system is used for 48 h or even longer (Kollef et al., 1997; Darvas and Hawkins, 2003). The cost effectiveness of OSS and CSS depends on the price of the suction catheters and duration of use (Kollef et al., 1997). Most publications profess that CSS are more expensive than OSS, but one states that OSS are the more expensive if the patient is suctioned more than 16 times a day (Johnson et al., 1994). If CSS is applied for four days without a change, it is less expensive than OSS (Maggiore, 2006). The effectiveness of closed suction systems needs to be investigated further, based on the clinical experience and the referenced bench test. Clinical trial examining the effect of CSS in non-sedated patients and patients ventilated by other ventilation methods than volume-controlled are needed. The cost effectiveness of CSS depends on, whether it is safe to use for en extended period. This should be further investigated. 27 What is the recommendation on closed versus open suction systems? Based on clinical controlled trials, closed and open suction systems are both recommended. There is little evidence to support that one system is superior to the other in terms of oxygen saturation, cardiovascular instability, secretion removal, incidence of VAP, environmental contamination, and cost. Discussion The literature review has demonstrated a paucity of good clinical trials covering the many aspects of the suctioning procedure. The widely accepted recommendations appear to be based on clinical experience and fairly limited documentation. When searching for the original sources for recommendations on the timing of suctioning, catheter size, pressure, insertion depth, duration, and oxygenation, most studies are relatively old, based on small sample sizes, or based on animal studies. As a consequence, there is room for improvement in the establishment of exact recommendations for clinical practice. The major recommendations seen in Table 1 may be used to guide nurses to provide safe and consistent pulmonary care, while reducing the complications and risks associated with suctioning. In the question of open versus closed endotracheal suctioning there appears to be more available evidence based on newer, larger and more substantial clinical controlled trials. More accurate recommendations for clinical practice are still needed, because most trials were conducted on heavily sedated and relaxed patients on volume-controlled ventilation, which is a thing of the past. Contemporary practice is determined by clinical protocols and lighter sedation together with more sophisticated modes of ventilation (Dellinger et al., 2008). A limitation to this study is the lack of strong evidence on the subject. In keeping with Sackett et al. (1996) we have attempted to provide the ‘best current evidence’ in this review. At this time the recommendations rely on the interpretation of a combination of experience and research. It is our hope that more reliable external evidence will be available in the future. Nurses need to be aware of the current best research evidence in order to make informed decisions. This literature review is intended as a step in the direction towards safer practice. The next step is the establishment of an expert group that will update the guideline every couple of years. When using a guideline, the nurse should always consider the external evidence in relation to the needs of the individual patient. The literature review has demonstrated the need for further investigations ranging from randomised controlled trials to qualitative studies of comfort and meaning. Finally, it may be stressed that the absence of evidence is not evidence of absence. Contribution/authorship CMP, MRN, JH contributed in the conception and design of the study; CMP, MRN, JH, IE in drafting the article; and the final approval was made by IE. 28 Table 1 C.M. Pedersen et al. Major recommendations for endotracheal suctioning Research question Recommendation What is the recommendation on routine versus ‘‘prn suctioning’’? What is the recommendation on suction catheter size? What is the recommendation on suction pressure? What is the recommendation on catheter insertion depth? What is the recommendation on the duration of the suction procedure? What is the recommendation on intermittent versus continuous suctioning? What is the recommendation on saline lavage? What is the recommendation on hyperoxygenation prior to suctioning? It is recommended that endotracheal suctioning should be performed only when necessary It is recommended that the suction catheter should occlude less than half of the lumen of the endotracheal tube It is recommended using the lowest possible suction pressure during endotracheal suctioning, usually 80—120 mmHg It is recommended using minimally invasive endotracheal suctioning in which the suction catheter is inserted to the length of the ET-tube only It is recommended that the suctioning procedure should last no longer than 15 s The recommendation is continuous rather than intermittent suctioning during the individual suction procedure What is the recommendation on hyperinflation prior to suctioning? What is the recommendation on infection control in relation to suctioning? What is the recommendation on closed versus open suction systems? Routine instillation of normal saline prior to endotracheal suctioning is not recommended Pre-oxygenation by the delivery of 100% oxygen for at least 30 s prior to and after the suctioning procedure is recommended to prevent decrease in oxygen saturation Hyperinflation combined with hyperoxygenation prior to suctioning is recommended on a non-routine basis Based on increased risk of infection, the use of aseptic technique is recommended Closed and open suction systems are both recommended References Ackerman MH. The effect of saline lavage prior to suctioning. Am J Crit Care 1993;2(4):326—30. Akgul S, Akyolcu N. Effects of normal saline on endotracheal suctioning. J Clin Nurs 2002;11(6):826—30. Almgren B, Wickerts CJ, Heinonen E, Hogman M. Side effects of endotracheal suction in pressure- and volume-controlled ventilation. Chest 2004;125(3):1077—80. Almgren B. Endotracheal suction a reopened problem [dissertation].Uppsala: Acta Universitatis Upsaliensis; 2005. 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