A Comparison of Infant Ventilation Methods Performed by Prehospital ...

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ORIGINAL CONTRIBUTION paramedic, ventilation; ventilation, infant

A Comparison of Infant Ventilation Methods Performed by Prehospital Personnel By comparing mouth-to-mouth ventilation to other methods, we tested whether there are significant differences among infant mannequin ventilation methods performed by emergency medical technicians-paramedics (EMT-Ps). Fifty-nine participants were evaluated in the performance of six ventilation methods; methods studied were mouth-to-mouth; two mouthto-mask devices; and infant, pediatric, and adult bag-valve-mask devices. By measuring each breath, the percentage of acceptable ventilations in predetermined ranges, 5 to 25 mL/kg or 10 to 20 mL/kg, was calculated. Methods were compared using repeat measures ANOVA testing. Correlation between ventilation performance and the experience of personnel was expressed as the Pearson correlation coefficient. There were no significant differences in performance between methods, except for inadequate ventilation with the Laerdal Pocket Mask ® (P < .05) from poor mask fit. The correlation between years of prehospital experience and the number of resuscitations versus ventilation performance was poor Single rescuer, EMTPs can successfully ventilate an infant mannequin with various size resuscitation bags. The Laerdal Pocket Mask ® is an ineffective device for infant mannequin ventilation and should not be recommended for infant resuscitation. [Terndrup TE, Kanter RK, Cherry RA: A comparison of infant ventilation methods performed by prehospital personnel. Ann Emerg Med June 1989;18:607-611.]

INTRODUCTION The etiology of cardiopulmonary arrest in pediatric patients is most commonly a primary respiratory disorder3 Despite generally poor resuscitation outcome for pediatric cardiac arrest, isolated respiratory arrest is more commonly associated with survival.Z, 3 The majority of deaths in children less than 1 year of age involve mechanisms likely to result in ambulance transportation. These mechanisms include poisoning, suffocation, sudden infant death syndrome, or injury from motor vehicular accidents. 4 Thus, most infants suffering cardiac or pulmonary arrest out of hospital will encounter prehospital personnel. Because prehospital personnel are the initial health care professionals to encounter infants in cardiopulmonary arrest, it is essential that they can perform skilled oxygenation and ventilation of these infants. The ability of prehospital providers to successfully ventilate adult mannequins with mouth-to-mask and bag-valve-mask {BVM) has previously been demonstrated. 5-7 The definitive management of the adult airway by emergency medical technicians-paramedics (EMT-Ps), with endotracheal intubation, is generally successful and improves outcome in selected patient groups. T M However, few studies have examined the effectiveness of ventilation or definitive airway management of pediatric patients by prehospital personnelA2,13 This paucity of data has occurred despite widely recognized differences in airway anatomy, equipment selection, and likely clinical settings when Compared with the aduhA 4 An evaluation of the initial ventilation methods available to prehospital personnel is needed to ensure their efficacy, reliability, and safety when performed on infants. No study has compared the currently available methods of infant ventilation performed by EMT-Ps. Therefore, we tested whether there are significant differences in performance between six methods of infant ventilation performed by EMT-Ps. 18:6 June 1989

Annals of Emergency Medicine

Thomas E Terndrup, MD*t Robert K Kanter, MD< Richard A Cherry, MS, NREMT-P* Syracuse, New York From the Departments of Critical Care and Emergency Medicine* and Pediatrics,t SUNY Health Sciences Center, Syracuse, New York. Received for publication September 26, 1988. Revision received February 17, 1989. Accepted for publication March 3, 1989. Presented at the Scientific Assembly of the American College of Emergency Physicians in New Orleans, September 1988. Address for reprints: Thomas E Terndrup, MD, Department of Critical Care and Emergency Medicine, SUNY Health Sciences Center, 750 E Adams Street," Syracuse, New York 13210.

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INFANT VENTILATION Terndrup, Kanter & Cherry

FIGURE 1. Percentage acceptable breaths versus ventilation method: loose criteria, 5 to 25 mL/kg.

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METHODS EMT-Ps were recruited from the Central New York Emergency Medical Service (EMS) area. All subjects were certified in basic and advanced cardiac life support. Mouth-to-mouth ventilation is the standard method for infant ventilation education and certification in this EMS area. Alt h o u g h certified to perform BVM ventilation of infants, no standard evaluation occurs with this method. None of the test subjects had participated in an infant ventilation training s e s s i o n w i t h i n the p a s t 12 months. Demographic data relative to age, sex, current level of training, years of experience as an EMT and paramedic, the number of episodes of ventilation.or CPR, and the number of e n d o t r a c h e a l i n t u b a t i o n s performed in the past five years on patients less than 16 years old and 16 years and older was collected. Simulated ventilation was assessed on an infant m a n n e q u i n (Laerdal Medical, Armonk, New York) whose size approximated that of a 4-kg infant. Elastic elements were added to the model lung to achieve a total respiratory static compliance of 1.8 mL/ cm H20 (ie, an infant with decreased pulmonary compliance). Total respiratory resistance of the model was 0.12 cm H 2 0 / m L / s e c (ie, increased respiratory resistance). Slight neck extension was required to avoid airway obstruction. Resuscitation equipment included the same infant-sized soft rubber mask (Laerdal #1, Laerdal Medical Corporation) for all BVM and mouthto-mask ventilations, excluding the Pocket Mask ®. Two c o m m e r c i a l m o u t h - t o - m a s k d e v i c e s (Laerdal Pocket Mask ® and the Infant Mouthto-Mask ® device, Vital Signs, Inc, Totowa, New Jersey) were used along with a disposable mouthpiece. Three self-inflating resuscitation bags were assessed: adult r e s u s c i t a t i o n bag (PMR-2 @, Puritan Bennett, Oakland Park, Kansas), m a x i m u m v o l u m e 1,760 mL, with the pressure relief valve (PRVJ closed; pediatric resuscitation bag (PMR-2®), m a x i m u m v o l u m e 870 mL, w i t h t h e PRV closed; and infant resuscitation bag (Pulmanex ®, Life Designs Systems, Carrollton, Texas), m a x i m u m vol20/608

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Ventilation Method 1

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ume 296 mL, with the PRV open. Mouth contact and ventilation with m o u t h - t o - m a s k was p e r f o r m e d through Resusei Face Shields ® (Laer~ dal Medical Corporation), in accordance with the American Heart Association 1986 guidelines for safety during CPR learning. Following a uniform set of verbal instructions, each unprepared EMT-P performed a 30-second trial with each of the methods, in random order. The verbal instructions w e r e : "This is a study of your ability to v e n t i l a t e an i n f a n t m a n n e q u i n . Please provide the mannequin with his entire ventilation requirement, based on visible chest wall expansion. Assume that no external cardiac compressions are ongoing, and that other physiologic derangements do not exist. Avoid excessive pressure and ventilation." Following the verbal instructions, a brief overview was given of the proper orientation and placement of the mouth-to-mask devices and the ventilation port with the Resusci Face Shield ® for mouthto-mouth ventilation. However, no actual mask application or airway positioning was demonstrated. OperAnnals of Emergency

Medicine

ators were blinded to all measurements, and no verbal feedback was provided to the EMT-Ps during the ventilation study. A mechanical pressure transducer was attached to the model lung. By constructing a compliance curve of the model lung, delivered volume was derived from measured pressure. Each breath was measured on a strip recorder. Recalibration of the compliance curve of the lung model was performed with 20, 40, 60, 80, and 100 mL of air, after each subject. Performance criteria were chosen prior to testing. Adequate ventilation was based on the percentage of ventilations in the acceptable range with each method. Strict criteria for acceptable breaths were 10 to 20 mL/kg (40 to 80 mL), whereas loose criteria were considered to be 5 to 25 mL/kg (20 to i00 mL). Results were expressed as the percentage of breaths in the acceptable range for each operator. The mean percentage of acceptable ventilations with the six methods was compared using repeated measures analysis of variance. Significant differences in performance with each 18:6 June 1989

F I G U R E 2. P e r c e n t a g e a c c e p t a b l e breaths versus v e n t i l a t i o n m e t h o d : strict criteria, 10 to 20 mL/kg.

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