Techniques for emergency ventilation through a needle cricothyroidotomy

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1 doi: /j x APPARATUS Techniques for emergency ventilation through a needle cricothyroidotomy M. D. Bould 1 and P. Bearfield 2 1 Fellow in Anaesthesia and Medical Education, St Michael s Hospital, University of Toronto, 30 Bond Street, Toronto, Ontario, Canada, M5B 1W8 2 Specialist Registrar in Intensive Care, The Royal Free Hospital, Pond Street, London, NW3 2QG, UK Summary We examined the pressures produced by a construction intended for emergency ventilation through a needle cricothyroidotomy. This construction consisted of a standard hospital wall oxygen supply, flowmeter, oxygen tubing and a three-way tap. We measured the flow achieved through a transtracheal catheter and compared the construction to a Manujet jet ventilator and to a Sanders injector. The construction performed similarly to the Manujet set at low pressures (0 100 kpa). To achieve similar pressures and flow to the Manujet set at pressures higher than 100 kpa required opening of the flowmeter beyond its calibrated range. The flow through the transtracheal catheter was almost three times higher when the flowmeters were fully opened than when they were opened to the 15 l.min )1 mark (44.5 vs 15.8 l.min )1, respectively; p < ). When the flowmeters were fully opened the pressure measured before the catheter was over four times higher than when they were only opened to the 15 l.min )1 mark (285.3 vs 66.4 kpa, respectively; p < ). This system of ventilation is inferior to a Manujet in terms of robustness and calibration throughout its range of pressures and flows, but seems appropriate for emergency use in the absence of a purpose-made jet ventilator.... Correspondence to: Dr M. D. Bould dylan.bould@utoronto.ca Accepted: 13 November 2007 Fifty years after the first description of needle cricothyroidotomy to save lives in the can t intubate, can t ventilate scenario [1], there is still controversy over how to provide oxygenation and ventilation after placing a transtracheal catheter [2]. In elective surgical settings with large numbers of patients, transtracheal high frequency jet ventilation has been shown to be safe and effective [3 5]. However, most hospitals and prehospital care facilities have neither access to nor experience with high frequency jet ventilators [2]. An alternative method of ventilation is low frequency jet ventilation with a device such as the Sanders injector with a manually controlled trigger that will deliver jet pressures of up to 400 kpa. The Manujet (VBM Medizintechnik GmbH, Sulz, Germany) has an adjustable dial to limit the maximum jetting pressure and a separate manually controlled trigger to control the respiratory rate. However, many hospitals do not have specialised equipment for low frequency jet ventilation in every area where a can t intubate, can t ventilate scenario may occur requiring cricothyroidotomy. The adult Advanced Life Support course manual suggests another alternative: connecting a cricothyroidotomy cannula to a high pressure oxygen supply with a three-way tap and occluding the open limb of the tap to provide ventilation [6]. Although the 4th edition recommended a set flow of l.min )1 [6], the current (5th) edition does not specify a flow rate [7]. The Paediatric Advanced Life Support course manual recommends using a 4-bar (400-kPa) oxygen supply with a flowmeter, starting oxygen flow at 1 l.min )1 per year of age, and increasing by increments of 1 l.min )1 if there is no chest movement [8]. A recent literature review described intermittent occlusion of oxygen tubing with a flow rate of 15 l.min )1 as a form of low-pressure ventilation. The Journal compilation Ó 2008 The Association of Anaesthetists of Great Britain and Ireland 535

2 M. D. Bould and P. Bearfield Æ Emergency ventilation through needle cricothyroidotomy Anaesthesia, 2008, 63, pages authors extrapolated from two previous studies to conclude that this low-pressure system results in failure of ventilation in adults in 60 s or less and should be abandoned [2]. The authors recommended that where a specialised jet ventilator with pressures of 45 psi (310.3 kpa) is unavailable, surgical cricothyroidotomy should be performed instead. Although the flow rates through various transtracheal catheters at different driving pressures have been investigated previously [9, 10], the flows and pressures achieved when various set flows from an oxygen flowmeter are delivered to a transtracheal catheter have not been studied. Our primary objective was to determine whether an effective high-pressure oxygen source could be constructed using a standard 400-kPa wall oxygen supply with flowmeter, oxygen tubing and a three-way tap. Methods Part 1 The preliminary part of our study compared measurements of flow and pressure from four different flowmeters, a Manujet and a Sanders injector. Each device was connected to the same 400-kPa wall oxygen outlet in a biomedical engineering laboratory to investigate the pressure-flow relationships in detail. Plastic oxygen tubing with a soft connector at both ends, such as is supplied with standard oxygen masks (Intersurgical, Berkshire, UK), was connected at one end to a standard hospital wall oxygen outlet with a flowmeter. The other end of the tubing was connected to the female Luer lock of an intravenous three-way tap (Vygon, Ecouen, France), which in turn was attached to the Luer lock of a transtracheal catheter [11] (Fig. 1). The oxygen tubing was 180 cm long and the lumen was star shaped to prevent kinking, with an internal diameter of approximately mm. When all of the ports of the threeway tap are open the remaining port can be intermittently occluded to provide low frequency jet ventilation. All measurements were completed with four different flowmeters: the Diamond Range, a single-headed Old Style and both outlets of a double-headed Old Style (Therapy Equipment, Potters Bar, UK). The same wall oxygen supply was used for comparative measurements with a Manujet jet ventilator and a Sanders injector (manufacturer unknown). Measurements with all flowmeter were made using one single oxygen outlet. We used a FlowAnalyser PF-300 TM (Imtmedical, Vaduz, Liechtenstein) to measure gas flow to an accuracy of ± 1.75% of readings (or ± 0.1 l.min )1 ) between ) 300 and 300 l.min )1 and pressure to an accuracy of ± 1% of readings (or ± 10 mbar) between 0 and 10 bar (0 and 1000 kpa). The pressure when the flowmeter oxygen Figure 1 Oxygen tubing, three-way tap and a Ravussin transtracheal catheter. The open limb of the three-way tap is intermittently occluded to provide low frequency jet ventilation. tubing system was directly attached to the FlowAnalyser PF-300 TM without a transtracheal catheter was measured and we shall refer to this as the occlusion pressure. A similar measurement was made by attaching the Sanders injector and Manujet directly to the pressure monitor. For comparative measurements of the Manujet, Sanders injector and flowmeter oxygen tubing system for an intermittent jet ventilation situation, each system was attached to a 16-G Ravussin catheter (VBM Medizintechnik GmbH) and pressure immediately proximal to the catheter was measured using the open limb of the three-way tap. We shall refer to this as the precatheter pressure. Flow was measured distal to the Ravussin catheter by attaching each ventilation system to a catheter inserted into the closed end of a length of plastic tubing attached to the flow sensor port of the FlowAnalyser PF-300 TM at its distal end. Part 2 The second part of the study was pragmatic: our research question was what pressures and flows would be achieved 536 Journal compilation Ó 2008 The Association of Anaesthetists of Great Britain and Ireland

3 M. D. Bould and P. Bearfield Æ Emergency ventilation through needle cricothyroidotomy if we found ourselves unexpectedly having to ventilate through a cricothyroidotomy without a dedicated jet ventilator? We investigated the flows and pressures that could be achieved by the construction of a flowmeter, oxygen tubing and a three-way tap using a variety of flowmeters in the theatres, recovery and intensive care units of two hospitals (Great Ormond Street Hospital for Children and the National Hospital of Neurology and Neurosurgery) areas that we thought had the potential for the can t intubate, can t ventilate situation. We then compared the findings with results obtained from the Manujet and Sanders injector in the preliminary part of the study. We measured the precatheter pressure and the flow through the catheter as previously described with flowmeters set at 1 15 l.min )1. We then made additional measurements beginning with the flowmeters set at 15 l.min )1, then opening the flowmeter beyond its calibrated range in ¼ turns. We examined 21 flowmeters of six different designs, made by three manufacturers (Therapy Equipment; Datex-Ohmeda Ltd, Stirling, UK; Medishield, London, UK). MINITAB 14 (State College, PA, USA) was used for statistical analyses. As data were not normally distributed, the Wilcoxon signed rank test was used to compare paired variables and the Mann Whitney U-test was used to compare unpaired variables. A value of p < 0.05 was considered to be statistically significant. Results Part 1 At a set flow rate of 1 l.min )1 all four flowmeters produced an occlusion pressure at equilibration higher than the kpa produced by the Manujet. There were no significant differences between occlusion pressures with the flowmeter set at 1 l.min )1 or 15 l.min )1, or when the flowmeter was fully opened. The flowmeters took longer for the pressure to equilibrate when partially open: it took over 4 s to reach occlusion pressure at 1 l.min )1 but < 1 s at 15 l.min )1. Occlusion pressures with the Manujet were very similar to those predicted by its set pressures. When set at a flow rate of 15 l.min )1 none of the flowmeters produced a precatheter pressure equal to the Manujet set at 1.1 bar (precatheter pressure 98.4 kpa). However, when the needle valves of the flowmeter were opened progressively past the 15 l.min )1 calibration the precatheter pressure continued to rise until in three cases the maximal pressure exceeded the pressure from the Manujet set at 4 bar (by 1.9%, 16.1% and 20.6%) and in one case achieved less pressure than the Manujet set at 4 bar (by 15.5%; Fig. 2). Similarly, flows continued to increase as the valves of the flowmeters were opened past Figure 2 Flow vs pressure for a Manujet ventilator (black triangles), a Sanders injector (single black circle) and four oxygen flowmeters (white triangles, circles and diamonds). the 15 l.min )1 mark and, when fully opened, flows of between 44.1 and 96.1 l.min )1 were produced. Precatheter pressure increased in an almost linear fashion when compared to flow, although of course when flow was > 15 l.min )1 the bobbin of the flowmeter was at the top of the flowmeter at all times and no longer provided useful information. Part 2 The precatheter pressure had a nonlinear relationship to the set flow (Fig. 3). The median (IQR [range]) pressure generated at 15 l.min )1 was 82.8 ( [47 103]) kpa, which fell between measurements from the Manujet when set at 110 and 160 kpa, producing precatheter pressures of 61.1 and 97.3 kpa, respectively. When the Figure 3 Set flow vs pressure measured proximally to a transtracheal catheter for 21 flowmeters. The central bars are the median, the boxes are the interquartile range, the whiskers the range. Journal compilation Ó 2008 The Association of Anaesthetists of Great Britain and Ireland 537

4 M. D. Bould and P. Bearfield Æ Emergency ventilation through needle cricothyroidotomy Anaesthesia, 2008, 63, pages Flow (l.min 1 ) Figure 4 Pressure measured proximally to a transtracheal catheter as flowmeters are opened beyond the calibrated range. The central bars are the median, the boxes are the interquartile range and the whiskers the range. The dotted line represents the maximal flow from the Manujet, and the broken solid line near the top of the graph the maximal pressure from the Sanders injector. flowmeters were opened beyond the calibrated range the precatheter pressure continued to increase. By the time the flowmeters were 1.5 full turns beyond 15 l.min )1 the pressure produced was ( [ ]) kpa, more than that of the Manujet set at 400 kpa (240.4 kpa; see Fig. 4). None of the flowmeters achieved a precatheter pressure as high as the Sanders injector (346.1 kpa). When the flowmeters were fully opened the precatheter pressure was over four times higher than when they were only opened to the 15 l.min )1 mark (285.3 vs 66.4 kpa, respectively; p < ). As expected, set flow on the flowmeters from 1 to 15 l.min )1 had a clear linear relationship to measured flow. The measured flow with the flowmeters set at 15 l.min )1 was 15.8 ( [ ]) l.min )1.By the time the flowmeter was opened 1.5 turns beyond 15 l.min )1 the flow produced was 39 ( [ ]) l.min )1, which was more than the flow produced by the Manujet set at 400 kpa (38.1 l.min )1 ; see Fig. 5). None of the flowmeters achieved flow as high as the Sanders injector (55.6 l.min )1 ). The flow through the transtracheal catheter was almost three times higher when the flowmeters were fully opened than when they were opened to the 15 l.min )1 mark (44.5 vs 15.8 l.min )1, respectively; p < ). Discussion The Manujet reduces both the pressure and the flow from the 4-bar wall oxygen outlet. The flowmeter on a wall oxygen outlet works by means of a needle valve that has Turns of flowmeter beyond calibrated range Figure 5 Flow through a transtracheal catheter as flowmeters are opened beyond the calibrated range. The central bars are the median, the boxes are the interquartile range and the whiskers the range. The dotted line represents the maximal flow from the Manujet, and the broken solid line near the top of the graph the maximal flow from the Sanders injector. the effect of reducing flow, although pressure is not affected if time is allowed for equilibration. This should not be considered a low pressure but a flow regulated system. In practice both systems work at pressures high enough to cause barotrauma. Basic principles of safety, such as watching the chest fall before delivering another jet, should always be adhered to. The Manujet uses a pressure regulator with a spring and membrane mechanism that can be adjusted by the operator (VBM Medizintechnik GmbH, personal communication). A Sanders injector uses a pressure regulator that cannot be adjusted by the operator and a small delivery nozzle to provide its jetting pressure. Ventilation is controlled by a finger valve [12]. Ryder and colleagues investigated a simple length of oxygen tubing as a technique for transtracheal ventilation but attached it to the oxygen flush on a Boyle s M anaesthetic machine using a 15-mm 6-mm tracheal tube connector [13]. The system was readily assembled in a median (IQR) time of 112 s ( s). However, flows of only 12 l.min )1 were achieved and it took 4 s to inflate a 500-ml model lung. The authors concluded that adequate lung inflation would only be possible if a purpose-made low frequency jet ventilation device were used. Craven and Vanner intermittently obstructed the end of an Ayre s T-piece, also connected to the oxygen flush of an anaesthetic machine using an artificial model lung. The system performed considerably less well than a Manujet but provided adequate minute ventilation in the absence of extreme upper airway obstruction: minute volume was over 5000 ml if upper airway resistance was equal or less than 72 cmh 2 O.l )1.s )1 [14]. In their recent 538 Journal compilation Ó 2008 The Association of Anaesthetists of Great Britain and Ireland

5 M. D. Bould and P. Bearfield Æ Emergency ventilation through needle cricothyroidotomy review, Scrase and Woollard extrapolated the findings from these two studies to conclude that systems based on intermittent obstruction of oxygen tubing with a 15 l.min )1 flow may provide an adequate pressure to inflate the lung but will fail within 60 s [2]. The pressure measured proximal to the catheter does not, of course, equal the pressure in any part of the airway during jet ventilation. This also depends on the resistance of the transtracheal catheter, the resistance of the airways, and the compliance of the lungs and chest wall. The precatheter pressure is used here simply as a convenient measure for comparison of purpose-built systems to a jet ventilation system readily constructed from routine ward and theatre equipment. Our findings suggest that intermittent occlusion of a system made from a high-pressure oxygen outlet, a flowmeter, oxygen tubing and a three-way tap has the potential to provide pressures that are comparable to a Manujet and adequate for low frequency jet ventilation. At 15 l.min )1 we found similar pressures and flows to when using a Manujet set at kpa, which is often sufficient for low frequency jet ventilation of a previously healthy adult [15]. When the flowmeters were opened above the 15 l.min )1 setting we found flows and pressures that compared to a Manujet set at 400 kpa. Our study has several clear limitations. In the second part, we chose to take only one measurement of flow and pressure from each flowmeter at each location and at each set flow. An alternative method would have been to take numerous measurements from flowmeters in the laboratory. Although this latter method would have provided more robust data on the performance of individual flowmeters our question was what the performance of the flowmeter oxygen tubing three-way tap would be on any one occasion, with equipment readily available, in locations where the can t intubate, can t ventilate scenario might have occurred. We found some obvious differences in the various types of flowmeter when conducting the study as the range of ¼ turns that could be made past the 15 l.min )1 mark ranged from 8 to 23 but this study was not designed to investigate or describe the differences in performance between flowmeters. Also, we only investigated six types of flowmeter from three different manufacturers and therefore cannot confidently extrapolate to the many other designs of flowmeter in current use. This system for jet ventilation is untested for prolonged use and is unlikely to be as durable as a purpose-made jet ventilation system. Due to these limitations this study must be regarded as a pilot and conclusions must be guarded. We consider that this system may be useful for the emergency resuscitation of adults, in whom the initial flow should be set at 15 l.min )1 as previously recommended. Should there be insufficient chest movement the valve should continue to be opened past the calibrated range until satisfactory movement is observed. Care must be taken to observe the chest falling in expiration before delivering another jet to reduce the incidence of barotrauma [3] and a surgical technique must be used if there is complete obstruction to expiration [16]. References 1 Jacoby J, Hamelberg W, Zeigler C. Transtracheal resuscitation. Journal of the American Medical Association 1956; 162: Scrase I, Woollard M. Needle vs surgical cricothyroidotomy: a short cut to effective ventilation. Anaesthesia 2006; 61: Jaquet Y, Monnier P, Van Melle G, Ravussin P, Spahn DR, Chollet-Rivier M. Complications of different ventilation strategies in endoscopic laryngeal surgery: a 10-year review. Anesthesiology 2006; 104: Smith RB, Schaer WB, Pfaeffle H. Percutaneous transtracheal ventilation for anaesthesia and resuscitation: a review and report of complications. Canadian Journal of Anaesthesia 1975; 22: Bourgain JL, Desruennes E, Fischler M, Ravussin P. Transtracheal high frequency jet ventilation for endoscopic airway surgery: a multicentre study. British Journal of Anaesthesia 2001; 87: Resuscitation Council (UK). Advanced Life Support, 4th edn. London: Resuscitation Council (UK), Resuscitation Council (UK). Advanced Life Support, 5th edn. London: Resuscitation Council (UK), Advanced Life Support Group. Advanced Paediatric Life Support, 4th edn. London: BMJ Books, Bougas TP, Cook CD. Pressure-flow characteristics of needles suggested for transtracheal resuscitation. New England Journal of Medicine 1960; 262: Attia RR, Battit GE, Murphy JD. Transtracheal ventilation. Journal of the American Medical Association 1975; 234: Ravussin P, Freeman J. A new transtracheal catheter for ventilation and resuscitation. Canadian Journal of Anaesthesia 1985; 32: Sanders RD. Two ventilating attachments for bronchoscopes. Delaware Medical Journal 1967; 39: Ryder IG, Paoloni CC, Harle CC. Emergency transtracheal ventilation: assessment of breathing systems chosen by anaesthetists. Anaesthesia 1996; 51: Craven RM, Vanner RG. Ventilation of a model lung using various cricothyrotomy devices. Anaesthesia 2004; 59: Cook TM, Nolan JP, Magee PT, Cranshaw JH. Needle cricothyroidotomy. Anaesthesia 2007; 62: Benumof JL, Scheller MS. The importance of transtracheal jet ventilation in the management of the difficult airway. Anesthesiology 1989; 71: Journal compilation Ó 2008 The Association of Anaesthetists of Great Britain and Ireland 539

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