The “Educated Hand” Can Anesthesiologists Assess Changes in Neonatal Pulmonary Compliance Manually

Spears, Robert S.; Yeh, Alice; Fisher, Dennis M.; Zwass, Maurice S.

doi:10.1097/00000542-199110000-00022

Cited by 63 publications

(29 citation statements)

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“…However, this has not been shown to any reliable extent and is rooted more in anecdote than evidence. 15 What has been shown to enhance ventilation performance with the anaesthesia bag is the attachment of a manometer, allowing more controlled ventilation in terms of peak pressures generated and overall mean airway pressure and thus oxygenation. 16 17 Zmora and Merritt 16 examined manual ventilation of a mannequin by paediatric staff both with and without a manometer.…”

Section: Discussionmentioning

confidence: 99%

Comparison of three manual ventilation devices using an intubated mannequin

Hussey

2004

Archives of Disease in Childhood - Fetal and Neonatal Edition

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Objective: To compare three devices for manual neonatal ventilation. Design: Participants performed a two minute period of ventilation using a self inflating device, an anaesthesia bag with attached manometer, and a Neopuff device. An intubated neonatal mannequin, approximating a 1 kg infant with functional lungs, was used for the study. Target ventilation variables included a rate of 40 breaths per minute, peak inspiratory pressure (PIP) of 20 cm H 2 O, and positive end expiratory pressure (PEEP) of 4 cm H 2 O. The circuit was attached to a laptop computer for data recording. Results: Thirty five participants were enrolled, including consultant neonatologists, paediatricians, and anaesthetists, paediatric and anaesthetic registrars, and neonatal nurses. The maximum PIP recorded using the self inflating bag, anaesthetic bag, and Neopuff device were 75.9, 35.5, and 22.4 cm H 2 O respectively. There were significant differences between the devices for mean PIP (30.7,18.1, and 20.1 cm H 2 O), mean PEEP (0.2, 2.8, and 4.4 cm H 2 O), mean airway pressure (7.6, 8.5, and 10.9 cm H 2 O), % total breaths ( 21 cm H 2 O PIP (39%, 92%, and 98%), and % total breaths > 30 cm H 2 O PIP (45%, 0, and 0). There was no difference between doctors and allied health professionals for the variables examined. Conclusion: The anaesthetic bag with manometer and Neopuff device both facilitate accurate and reproducible manual ventilation. Self inflating devices without modifications are not as consistent by comparison and should incorporate a manometer and a PEEP device, particularly when used for resuscitation of very low birthweight infants.T he reported need for positive pressure ventilation in newborn infants has varied from about 2% in the 1970s to 1% in the early 1990s.1-3 Infants receiving ventilatory support often require brief periods of manual ventilation for reasons including acute deterioration, equipment failure, patient transfer, and clinical assessment. 4 Loss of face mask seal and loss of pressure in the ventilation bag can lead to inadequate resuscitation.5 Although ventilation is essential for resuscitation, excessive inspiratory pressures can lead to volutrauma, particularly in very low birthweight infants. [6][7][8] Inadequate positive end expiratory pressure (PEEP) and the resultant inadequate end expiratory lung volume augments lung injury by allowing repetitive expansion and collapse of the terminal airways and alveolar units (atelectrauma). 9There are several methods of providing manual ventilation. Self inflating devices are operated by squeezing and releasing a semirigid silicone bag to deliver each breath to the patient. They are portable and easy to use. They usually include a pressure limiting safety valve and can deliver room air without an independent gas flow. Flow dependent anaesthesia bags are squeezed to deliver each breath, and pressure release valves can be attached to limit peak pressures. Their accurate use requires training and skill but they can facilitate both prolonged inspirations and PEEP. The N...

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Section: Discussionmentioning

confidence: 99%

Comparison of three manual ventilation devices using an intubated mannequin

Hussey

2004

Archives of Disease in Childhood - Fetal and Neonatal Edition

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“…Neither of these concerns is well founded in the literature. [3][4][5][6] When peak inspiratory pressures are titrated to achieve tidal volumes up to 10 ml/kg, PCV results in lower peak inspiratory flow and pressure compared with manual circle system ventilation with the use of an airway pressure release valve. So long as peak airway pressures are 15 cm H 2 O or less, gastric insufflation does not occur.…”

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confidence: 99%

A Two-handed Jaw-thrust Technique Is Superior to the One-handed “EC-clamp” Technique for Mask Ventilation in the Apneic Unconscious Person

2010

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Background: Mask ventilation is considered a "basic" skill for airway management. A one-handed "EC-clamp" technique is most often used after induction of anesthesia with a two-handed jaw-thrust technique reserved for difficult cases. Our aim was to directly compare both techniques with the primary outcome of air exchange in the lungs. Methods: Forty-two elective surgical patients were maskventilated after induction of anesthesia by using a onehanded "EC-clamp" technique and a two-handed jaw-thrust technique during pressure-control ventilation in randomized, crossover fashion. When unresponsive to a jaw thrust, expired tidal volumes were recorded from the expiratory limb of the anesthesia machine each for five consecutive breaths. Inadequate mask ventilation and dead-space ventilation were defined as an average tidal volume less than 4 ml/kg predicted body weight or less than 150 ml/breath, respectively. Differences in minute ventilation and tidal volume between techniques were assessed with the use of a mixed-effects model. Results: Patients were (mean Ϯ SD) 56 Ϯ 18 yr old with a body mass index of 30 Ϯ 7.1 kg/m 2 . Minute ventilation was 6.32 Ϯ 3.24 l/min with one hand and 7.95 Ϯ 2.70 l/min with two hands. The tidal volume was 6.80 Ϯ 3.10 ml/kg predicted body weight with one hand and 8.60 Ϯ 2.31 ml/kg predicted body weight with two hands. Improvement with two hands was independent of the order used. Inadequate or dead-space ventilation occurred more frequently during use of the one-handed compared with the two-handed technique (14 vs. 5%; P ϭ 0.013). Conclusion: A two-handed jaw-thrust mask technique improves upper airway patency as measured by greater tidal volumes during pressure-controlled ventilation than a onehanded "EC-clamp" technique in the unconscious apneic person.

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“…We can only speculate as to why there is such widespread overestimation of V,, but this finding does seem to indicate that anaesthetists are optimistic regarding the adequacy of their patients' ventilation. Previous studies, attempting to assess the ability of anaesthetists to monitor clinically the respiratory system, have focused on detecting changes in pulmonary compliance, from palpation of the reservoir bag, the so-called 'educated hand' [3][4][5]. These studies, of both adult [3,4] and paediatric [S] anaesthetic practice, have shown the 'educated hand' to be a myth, and that even very experienced anaesthetists cannot estimate the patient's lung compliance.…”

Section: Discussionmentioning

confidence: 99%

Estimation of tidal volume from the reservoir bag

Kulkarni

Lumb²,

Platt³

et al. 1992

Anaesthesia

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SummaryThe accuracy of 21 anaesthetists in estimating tidal volumes from reservoir bag movements was assessed using a model lung apparatus. The breathing system configuration (Mapleson A or D ) , the grade of anaesthetist. and the years of anaesthetic experience had no effect on accuracy. Greater precision of tidal volume estimation was observed with larger tidal volumes and lower fresh gasflows. The mean systematic error of 18 of the 21 anaesthetists was greater than zero, indicating a general tendency to overestimate tidal volume. This study therefore strengthens the view that clinical observations should hi> supplemented with information from continuous monitoring devices. Key wordsApparatus; reservoir bag. Ventilation; tidal volume.Anaesthetists spend a large proportion of their time monitoring spontaneously breathing patients using a combination of clinical observation of chest and reservoir bag movements and continuous monitoring devices [I]. However, anaesthetists often question the adequacy of tidal volume (V,) estimation from simply watching the reservoir bag, and we are unaware of any study which indicates the precision of these observations. The size of reservoir bag excursion is not solely dependent on V,, but is also likely to be affected by fresh gas flow rate and breathing system configuration. We therefore studied the expertise of anaesthetists of varying experience in assessing V, under differing conditions of fresh gas flow and with two different breathing systems. MethodsA ventilator (Medishield CPU 1) was set to drive the model lung decribed by Lyle et al. [2]. This was connected, in place of the patient, to either a Mapleson A (Magill) or Mapleson D coaxial (Bain) breathing system with a 2 I reservoir bag, so providing simulation of a spontaneously breathing patient. The ventilator was set to deliver tidal volumes of 100, 300, 500 and 700 ml with fixed respiratory frequency (breath.min-') and I : E ratio. The tidal volume delivered by the ventilator was validated with an 8 I wet spirometer calibrated with a 1.5 I gas syringe, and shown to be within 10% of the desired VT on five repeated measurements. The flow meters on the anaesthetic machine were set to give fresh gas flows (FGFs) of 3, 6, 9 and 12 I.min-'.Twenty-one anaesthetists of varying experience were recruited to the study and asked to estimate the tidal volume simply by observing a reservoir bag ('rebreathing bag'). The experiment was carried, out during the course of a normal working day, provided the anaesthetist had not been on call the previous night. The aim of the experiment was explained to the subjects, who were asked to estimate V, to the nearest 100 ml. They were also told that the maximum V, was less than a litre. Each subject was seated in front of the anaesthetic machine with a screen placed between the anaesthetic machine and the model lung, such that the subject could visualise the fresh gas flow, the breathing system, and the reservoir bag, but not the ventilator or the model lung. Each anaesthetist estimated the V, ...

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The “Educated Hand” Can Anesthesiologists Assess Changes in Neonatal Pulmonary Compliance Manually

Cited by 63 publications

References 0 publications

Comparison of three manual ventilation devices using an intubated mannequin

Comparison of three manual ventilation devices using an intubated mannequin

A Two-handed Jaw-thrust Technique Is Superior to the One-handed “EC-clamp” Technique for Mask Ventilation in the Apneic Unconscious Person

Estimation of tidal volume from the reservoir bag

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