Manual bulb suction is commonly used in delivery rooms and in the home setting to clear upper airways of copious secretions. Even though these manual bulb suction devices are frequently used, no comprehensive, evidence-based, clinical guidelines are in place to describe effective manual suction bulb use to avoid or reduce upper airway injury. Little empirical evidence is known about human factors and the mechanical use of manual bulb suction. This study is the first step in developing clinical guidelines for the safe and effective mechanical use of manual bulb suction to reduce and avoid upper airway injury.
Two human factors related to bulb compression are preferred: hand placement and the relative negative pressure generated. Manual bulb suction devices work by manually compressing the device either radially (radius or side) or axially (back or end), and negative suction pressure occurs when the compression of the bulb is released (Figure 1). For example, in the neonatal population, it is known that vigorous pharyngeal suctioning can lead to laryngeal spasms, vagal bradycardia, decreased arterial oxygen saturation, and possibly delay the onset of breathing (Carrasco, Martell, & Estol, 1997; Cordero & Hon, 1971; Gungor et al., 2006; Waltman, Brewer, Rogers, & May, 2004). Based on these findings, practice changes have occurred and suctioning is now recommended only when copious secretions are present in the upper airways (Wyckoff et al., 2015). One effective, quick, and convenient way to remove occlusive secretions is by using a manual bulb suction device. It is important to identify appropriate hand placement on a manual bulb suction device and the associated negative pressure generated to ensure that the suction pressures are not too high to cause potential pharyngeal injury. A knowledge gap exists about how the mechanical use of manual bulb suction may be used to promote safe suctioning and reduce and prevent injury when removing copious secretions to aid in airway clearance.
Various human factors are assumed to be involved in the mechanical function of the bulb, such as individual hand placement preference (radial or axial) and bulb air displacement based on the perception of the force of compression then release to generate negative suction. Negative suction pressure with axial compression is postulated to be higher than radial compression because axial compression elicits a more complete collapse of the bulb. Axial compression causes the end of the bulb to rest at the opening of the bulb with little to no air pocket entrapment in the bulb; thus, more negative force is probable when the compression is released as compared to radial compression. Radial compression only collapses the sides of the bulb, leaving a space near the axial position of the bulb where air may remain in the bulb. It is assumed when air remains in a bulb with radial compression then the total negative suction force would be less than with an axial compression, which causes complete collapse of the bulb. The negative pressure generated when using a manual suction bulb is important to know to ensure that the device is safe to use. Hand placement on the bulb may be a human factor that influences the amount of negative force generated, and hand placement can easily be modified to promote effective, yet safe, suction pressures and effective airway clearance. The influence of human factor variation may provide information on bulb safety related to negative suction pressure generated.
Currently, there are no specific standards identifying appropriate negative suction pressure in naso-oropharyngeal airway clearance. Referring back to the population of neonates, the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care (ERC) adopted the position of the ERC and Cardiovascular Care Science with Treatment Recommendations Guidelines and recommended suctioning of neonates only to clear the airway of any obstructive, copious secretions (Wyllie et al., 2015). However, no recommendations of how to technically use a bulb device to effectively clear the airways are provided, and no safe recommendations for upper airway negative suction pressures are indicated. Pediatric Advance Life Support mentioned suctioning secretions that may occlude the small diameter of an oropharyngeal or nasopharyngeal inserted airway, but suction devices and optimal suction pressure to maintain a patent airway are not identified or discussed (de Caen et al., 2015). When performing endotracheal suctioning in neonates, the American Association for Respiratory Care (AARC) guidelines recommend a maximum suction force of negative 80–100 mm Hg (AARC, 2010). No specific negative pressure ranges associated with manual bulb suction are recommended by any national or international organizations.
Alur, Liss, Ferentino, and Super (2012) conducted a study on the use of three bulb sizes (1 oz., 2 oz., and 3 oz.) and three brands (Bard, Cardinal, and Medline). They extrapolated suction parameters from various animal studies and used a conservative approach of 100 mm Hg negative pressure as a standard for upper airway clearance when using all devices. The sample in their study consisted of 25 newborn care providers who each compressed six different bulbs three times each, and a pneumatic transducer system measured negative pressures. They found the average negative pressure of 1-oz. bulbs to be 128.7 mm Hg, of 2-oz. bulbs to be 94.7 mm Hg, and of 3-oz. bulbs to be 88 mm Hg. The highest negative suction pressure was with a 1-oz. bulb at 169.0 mm Hg. A 2-oz. bulb yielded a negative pressure as high as 146.9 mm Hg. The 3-oz. bulb was the only bulb that consistently yielded pressures less than 100 mm Hg, and the authors concluded that a 3-oz. bulb may be too large to be used in neonates. Human factors such as hand placement for compression were not reported. Even though a 2-oz. bulb is frequently used in practice and home settings, current evidence from one study does not recommend the use of a 2-oz. bulb because negative suction pressures were consistently found to be greater than 100 mm Hg (Alur et al., 2012). Additional studies are needed to explore negative suction pressures associated with a commonly used 2-oz. bulb and the influence of human factors in order to develop clinical guidelines for mechanical manual suction use.
This article describes findings from a study exploring human factors, such as hand placement and negative pressure generated by a commonly used 2-oz. manual bulb suction device, as a first step in developing clinical guidelines for the safe and effective use of manual bulb suction to reduce and avoid upper airway injury. The objectives of this study were to identify the relationships of a 2-oz. manual bulb suction device with (a) gender, (b) hand placement (radial or axial), (c) volume of air expelled, (d) perceived level of pressure applied, and (e) the negative suction pressure generated.
Study Sample and Setting
This prospective, exploratory interdisciplinary (nursing and engineering) study was approved by the institutional review board. A convenience sampling method was chosen to be representative of healthcare providers and parents who may use the manual bulb suction device. Parents were considered appropriate for this sample because they may use the bulb in the home setting to promote airway clearance. Inclusion criteria were subjects had to be a minimum of 19 years old and knowledgeable of the English language. The setting occurred at a large university in the southern United States.
Manual Bulb Suction Testing
The subjects were approached and informed about the study, and consent was obtained. The subject was asked to pick up the 2-oz. manual bulb suction device (Dynarex number 4910 Bulb Syringe) from a table and compress. No coaching or instructions were provided to the subject to avoid any bias in hand placement. Subjects were also asked to compress the bulb and estimate “how hard” they compressed on a scale from 0 (no pressure) to 10 (as hard as you can squeeze). The hand placement (radial or axial) on the bulb suction device and the volume of air displaced were observed and recorded.
Additional pressure testing was conducted to assess the bulb's air volume displacement and negative suction pressure generated. A pressure transmitter system (PTS) was used with a negative pressure range of 0 to 375 mm Hg, and it was calibrated with a Fluke model 7252i digital pressure controller/calibrator. This process for internal consistency involved a total of 666 measurements obtained with a 2-oz. manual bulb suction device using the PTS.
Data were collected and entered in the Statistical Package for the Social Sciences (SPSS) Version 23 statistical software. Nonparametric tests were used to analyze significance set at an α of .05. Descriptive statistics, χ2, Mann-Whitney U, and regression were used to analyze the data.
The sample size included 87 people, and the majority were female (55%). Of the entire sample, hand placement was 55% radially and 45% axially. Females were more likely to choose radial hand placement than males (58% compared to 51%) (Figures 2 and 3). Males tended to have higher negative pressures (maximum, −81 mm Hg) when radially compressing the bulb. Females generated higher negative pressures (−77 mm Hg) when axially compressing the bulb. The range of negative pressures with radial compression were 42 to 81 mm Hg: Axial compression negative pressures ranged from 50 to 77 mm Hg. When asked about how hard the bulb was compressed, the most often occurring ranking for the perceived level of compression was a scale of 5 (25%).
Statistical significance was observed between gender and axial hand placement and negative pressure generated (U = 71.50, p = .001): The mean rank of females (25.93) was higher than that of males (13.76). Gender and radial hand placement and negative pressure generated was also found to be statistically significant (U = 170, p = .021): The mean rank of females (20.57) was lower than that of males (30). Using the PTS, total (both radial and axial) suction pressures were predicted from −42 to −81 mm Hg, with a standard deviation of −7 mm Hg. The mean pressure generated with either a radial or axial hand placement was predicted to be −58 and −60 mm Hg, respectively. No significant association was observed between gender, prior use of the bulb, hand placement, or volume of air expelled.
Airway patency is a priority when secretions occlude airflow in the upper airways. The aim of this work is to build a body of empirical evidence to develop clinical guidelines on the mechanical use of the manual bulb suction to promote effective and safe airway clearance. The findings of this study identify that human factor preferences for hand position (either radial or axial) yield safe negative suction pressures (less than 85 mm Hg) when the manual bulb suction device is compressed then released. The average suction pressures were below the safe ranges of negative suction pressure for wall vacuum suction (80–100 mm Hg) recommendations by national organizations (AARC, 2010; Wyllie et al., 2015). Alur et al. (2012) did not find negative suction pressures consistently less than 100 mm Hg when healthcare providers were using a 2-oz. manual bulb device. Key differences in these studies were the brands of 2-oz. manual bulbs used and how negative pressure was measured.
Human factor variability was identified in negative suction pressures by hand placement (radial or axial) and gender. Most individuals have a preference for radial hand placement. Further studies are needed to explore additional human factors associated with hand placement, hand size, hand strength, and negative suction pressure. These additional human factors will provide information to be considered when instructing healthcare providers and parents in the mechanical use of the bulb.
An interesting finding was that regardless of negative suction pressure generated, study participants perceived they were eliciting a “moderate” level of compression. This is an important finding because the bulb needs to be compressed sufficiently for negative suction to evacuate copious secretions. If the bulb is “lightly” compressed and the negative suction generated is insufficient to aspirate secretions, then the patient may remain in distress. Teaching healthcare providers and parents where to properly place their hand on the bulb (radial or axial) and the amount of force needed to compress the bulb is important to ensure the appropriate function of the suction device to remove copious secretions.
There are several limitations in this study. This study did not inquire about past training in how to use the bulb suction device. Hand strength was not measured and used as a covariate. A larger and more diverse sample to include healthcare providers who work with neonates and children would strengthen the design of the study. Manual suction bulbs from a variety of different manufacturers were not reviewed to identify if there were differences between manufacturers. Using different pressure measuring systems to correlate negative pressure findings would support the robustness of the findings.
Healthcare providers and parents commonly use a 2-oz. manual suction device to promote airway clearance in inpatient and outpatient settings, and radial or axial hand placement yields safe negative suction pressure ranges when using a 2-oz. manual bulb device. Clinical implications of this study are that it is safe to use a 2-oz. bulb to promote airway clearance and compressing the bulb in the radial or axial position is acceptable. This study contributes information for clinical guideline development to instruct how to most effectively and safely use the manual bulb device.
This is the first step in assessing human factors and the mechanical use of a manual bulb suction. Additional studies are needed to measure pressure dynamics with a variety of manual bulb suction devices currently on the market. Polymer construction, collapsibility, rebound inflation, and suction effectiveness are a few device variables to further explore. Human factor variables related to the patient, such as mucosal tissue integrity with a manual suction device and secretion viscosity influence on suction pressure required for effective evacuation, need to be further explored. Human factor variables related to healthcare providers and parents to be assessed include how to promote nare occlusion for optimal suction effectiveness, sufficient secretion removal with either a quick release or slow controlled negative pressure release method, and effective neonatal positioning for comfort and maximal secretion removal.
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Keywords:Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved
manual bulb; naso-oropharyngeal; suction; upper airway