Disposable laryngeal tube suction: standard insertion technique versus two modified insertion techniques for patients with a simulated difficult airway

Objective

The disposable laryngeal tube suction (LTS-D) is a supraglottic airway device that can be used as an alternative to tracheal tube to provide ventilation. We tested the hypothesis that, with a frontal jaw thrust insertion technique (FIT/JT), the rate of correct placement attempts in patients with a simulated difficult airway by means of a rigid cervical immobilization collar could be significantly increased compared to the standard insertion technique (SIT) recommended by the manufacturer.

Methods

70 adult patients undergoing trauma surgery under general anaesthesia had an LTS-D inserted, randomly assigned to the SIT or FIT/JT. In the FIT/JT, the operator was standing in front of the patient's head, and forced chin lift to create sufficient retropharyngeal space was performed. The rate of successful tube placements within 180 s and with a maximum of two attempts was the main outcome variable. To distinguish between the effects of the frontal approach and the jaw thrust manoeuvre, a third group was studied after completion of the SIT and FIT/JT groups. The standard insertion technique, but with a jaw thrust manoeuvre (SIT/JT), was employed in another 35 consecutive patients.

Results

Overall placement success was 49% (SIT, 17/35 patients, P < 0.001), 91% (SIT/JT, 32/35 patients) and 100% (FIT/JT). The time required for successful insertion was shortest in the FIT/JT group (23 ± 6 s), and significantly longer in the SIT/JT (42 ± 29 s, P < 0.001) and SIT groups (51 ± 29 s, P < 0.0001).

Conclusion

In anaesthetised patients with a simulated difficult airway created with a rigid cervical collar, the overall LTS-D placement success was significantly higher when a jaw thrust manoeuvre was performed, regardless of the particular technique used to introduce the LTS-D. Therefore, an intense jaw thrust manoeuvre should be performed whenever an LTS-D is being inserted.     

Out-of-hospital airway management by paramedics and emergency physicians using laryngeal tubes

Concept

Endotracheal intubation (ETI) is considered to be the gold standard of prehospital airway management. However, ETI requires substantial technical skills and ongoing experience. Because failed prehospital ETI is common and associated with a higher mortality, reliable airway devices are needed to be used by rescuers less experienced in ETI. We prospectively evaluated the feasibility of laryngeal tubes used by paramedics and emergency physicians for out-of-hospital airway management.

Material and methods

During a 24-month period, all cases of prehospital use of the laryngeal tube disposable (LT-D) and laryngeal tube suction disposable (LTS-D) within five operational areas of emergency medical services were recorded by a standardised questionnaire. We determined indications for laryngeal tube use, placement success, number of placement attempts, placement time and personal level of experience.

Results

Of 157 prehospital intubation attempts with the LT-D/LTS-D, 152 (96.8%) were successfully performed by paramedics (n = 70) or emergency physicians (n = 87). The device was used as initial airway (n = 87) or rescue device after failed ETI (n = 70). The placement time was ≤45 s (n = 120), 46-90 s (n = 20) and >90 s (n = 7). In five cases the time needed was not specified. The number of placement attempts was one (n = 123), two (n = 25), three (n = 2) and more than three (n = 2). The majority of users (61.1%) were relative novices with no more than five previous laryngeal tube placements.

Conclusion

The LT-D/LTS-D represents a reliable tool for prehospital airway management in the hands of both paramedics and emergency physicians. It can be used as an initial tool to secure the airway until ETI is prepared, as a definitive airway by rescuers less experienced with ETI or as a rescue device when ETI has failed.     

A prospective evaluation of the efficacy of the laryngeal mask airway during neonatal resuscitation

Objective

To study the feasibility, efficacy and safety of using the laryngeal mask airway (LMA) in neonatal resuscitation.

Methods

In total, 369 neonates (gestational age ≥34 weeks, expected birth weight ≥2.0 kg) requiring positive pressure ventilation at birth were quasi-randomised to resuscitation by LMA (205 neonates) or bag-mask ventilation (164 neonates).

Results

(1) Successful resuscitation rate was higher with the LMA compared with bag-mask ventilation (P < 0.001) and the total ventilation time was shorter with the LMA than with bag-mask ventilation (P < 0.001). Seven of nine neonates with an Apgar score of 2 or 3 at 1 min after birth were successfully resuscitated in the LMA group, while in the BMV group all six neonates with an Apgar score of 2 or 3 at 1 min required tracheal intubation and ventilation. In neonates with an Apgar score of 4 or 5 at 1 min after birth, successful resuscitation rate with the LMA was higher than with bag-mask ventilation (P < 0.01). (2) Successful insertion rate of the LMA at the first attempt was 98.5% and the insertion time was 7.8 s ± 2.2 s. There were few adverse events (vomiting and aspiration) in the LMA group.

Conclusion

The LMA is safe, effective and easy to implement for the resuscitation of neonates with a gestational age of 34 or, more weeks.     

An evaluation of bag-valve-mask ventilation using an ergonomically designed facemask among novice users: A simulation-based pilot study

Purpose

We sought to compare the ability of novice operators to provide artificial ventilation using a standard facemask and a new ergonomically designed facemask. Whether or not proper technique was used was also assessed.

Methods

Thirty-two allied-health students used both masks in random crossover fashion to ventilate an airway trainer. Breaths were delivered by a mechanical ventilator and exhaled tidal volume was recorded for each of 12 breaths for each participant for each mask. The effect of each mask during ventilation over time was assessed using repeated-measures ANOVA. Assessment of mask technique among participants and association between mask type and hand repositioning were analyzed using the Wilcoxon-Rank Sum Test and McNemar's paired proportions test, respectively.

Results

The tidal volume achieved when participants used the ergonomic mask was higher than when participants used the standard mask by the fourth breath (361 ± 104 mL vs. 264 ± 163 mL; Bonferroni adjusted p-value = 0.040) and increased over time. The repeated-measures ANOVA showed that the ergonomic mask consistently resulted in higher tidal volumes than the standard mask regardless of rescuer's gender. Over time the standard mask resulted in a linear decrease in tidal volume of −10 mL/breath (estimated difference in decay of 10 mL/breath versus the ergonomic mask; p < 0.001).

Conclusion

Novice airway operators were better able to provide facemask ventilation using an ergonomically designed mask than with a traditional facemask. We conclude that better hand position facilitating improved mask seal and less operator fatigue account for our findings.     

A comparison of the I-gel supraglottic airway as a conduit for tracheal intubation with the intubating laryngeal mask airway: A manikin study

Background

Insertion of a supraglottic airway and tracheal intubation through it may be indicated in resuscitation scenarios where conventional laryngoscopy fails. Various supraglottic devices have been used as conduits for tracheal intubation, including the intubating laryngeal mask airway (ILMA), the Ctrach™ laryngeal mask and the I-gel supraglottic airway.

Methods

A prospective study with 25 participants evaluated the success rate of blind intubation (using a gum-elastic bougie, an Aintree intubating catheter (AIC) and designated tracheal tube) and fibrescope-guided tracheal intubation (through the intubating laryngeal mask airway and the I-gel supraglottic airway) on three different airway manikins.

Results

Twenty-five anaesthetists performed three intubations with each method on each of three manikins. The success rate of the fibrescope-guided technique was significantly higher than blind attempts (P < 0.0001) with both devices. For fibreoptic techniques, there was no difference found between the ILMA and I-gel (P > 0.05). All blind techniques were significantly more successful in the ILMA group compared to the I-gel (P < 0.0001 for bougie, Aintree catheter and tracheal tube, respectively).

Conclusions

The results of this study show that, in manikins, fibreoptic intubation through both ILMA and I-gel is a highly successful technique. Blind intubation through the I-gel showed a low success rate and should not be attempted.     

Efficacy of ventilation and ventilation adjuncts during in-water-resuscitation—A randomized cross-over trial

Introduction

Drowning is a common cause of death in young adults. The 2010 guidelines of the European Resuscitation Council call for in-water-resuscitation (IWR). There has been controversy about IWR amongst emergency and diving physicians for decades. The aim of the present study was assessing the efficacy of IWR.

Methods

In this randomized cross-over trial, nineteen lifeguards performed a rescue manoeuvre over a 100 m distance in open water. All subjects performed the procedure four times in random order: with no ventilation (NV) and transportation only, mouth-to-mouth ventilation (MMV), bag-mask-ventilation (BMV) and laryngeal tube ventilation (LTV). Tidal volumes, ventilation rate and minute-volumes were recorded using a modified Laerdal Resusci Anne manikin. Furthermore, water aspiration and number of submersions of the test mannequin were assessed, as well as the physical effort of the lifeguard rescuers.One lifeguard subject did not complete MMV due to exhaustion and was excluded from analysis.

Results

NV was the fastest rescue manoeuvre (advantage ∼40 s). MMV and LTV were evaluated as efficient and relatively easy to perform by the lifeguards. While MMV (mean 199 ml) and BMV (mean 481 ml) were associated with a large amount of aspirated water, aspiration was significantly lower in LTV (mean 118 ml). The efficacy of ventilation was consistently good in LTV (V_t = 447 ml), continuously poor in BMV (V_t = 197) and declined substantially during MMV (V_t = 1019 ml initially and V_t = 786 ml at the end). The physical effort of the lifeguards was remarkably higher when performing IWR: 3.7 in NV, 6.7 in MMV, 6.4 in BMV and 4.8 in LTV as measured on the 0–10 visual analogue scale.

Conclusion

IWR in open water is time consuming and physically demanding. The IWR training of lifeguards should put more emphasis on a reduction of aspiration. The use of ventilation adjuncts like the laryngeal tube might ease IWR, reduce aspiration of water and increase the efficacy of ventilation during IWR.     

Comparison of prehospital insertion success rates and time to insertion between standard endotracheal intubation and a supraglottic airway

Objective

To compare paramedic insertion success rates and time to insertion between standard ETI and a supraglottc airway device (King LTS-D™) in patients needing advanced airway management.

Methods

Between June 2008 and June 2009, consented paramedics from 4 EMS systems performed ETI or placed a King LTS-D according to a predetermined randomization calendar. Data collection occurred following each placement via telephone. Placement success (ability to ventilate to chest rise, absence of gastric sounds, presence of bilateral lung sounds, and when applicable, quantitative end-tidal CO₂ reading) was compared between treatment groups. Time to ventilation (time from airway device in hand ready to place to time of first successful ventilation) was also compared.

Results

A total of 213 patients in need of advanced airway management were treated during the study period, with 9 patients excluded from the analysis. The remaining 204 placements by 110 of the 272 consented paramedics were analyzed (median placements per paramedic = 1; range = 1-7). The overall placement success rate was virtually equal across the two groups (ETI = 80.2%, King LTS-D = 80.5%; p = 0.97). The median time to placement between ETI and the King LTS-D was also not significantly different (ETI = 19.5 s vs. King LTS-D = 20.0 s; z = −0.25; p = 0.80).

Conclusion

In this study, no differences in placement success rate or time to insertion were detected between the King LTS-D and ETI.     

Complications associated with the prehospital use of laryngeal tubes—A systematic analysis of risk factors and strategies for prevention

Objective

With the increasing spread of laryngeal tubes (LT) in emergency medicine, complications and side-effects are observed. We sought to identify complications associated with the use of LTs in emergency medicine, and to develop strategies to prevent these incidents.

Methods

In a prospective clinical study, all patients who had their airways managed in the field with a LT and who were admitted through the emergency department of the Frankfurt University Hospital during a 6 year period were evaluated using anonymised data collection sheets. A team of experts was available 24/7 and was requested whenever a patient was admitted with a LT in place. This team evaluated the condition of the patients with respect to prehospital airway management and was responsible for further advanced airway management. All complications were analysed, and strategies for prevention developed.

Results

One hundred eighty nine patients were included and analysed. The initial cuff pressure of the LTs was 100 cm H₂O on the median. Complications consisted of significant tongue swelling (n = 73; 38.6%), resulting in life-threatening cannot ventilate, cannot intubate scenarios in two patients (1.0%) and the need for surgical tracheostomy in another patient, massive distension of the stomach (n = 20, 10.6%) with ventilation difficulties when LTs without gastric drainage were used; malposition of the LT in the piriform sinus (n = 1, 0.5%) and significant bleeding from soft tissue injuries (n = 4, 2.1%).

Conclusions

The prehospital use of LTs may result in severe and even life-threatening complications. Likely, such complications could have been prevented by using gastric drainage and cuff pressure adjustment. Both, prehospital health care providers and emergency department staff should develop a greater awareness of such complications to best avoid them in the future.     

Intrathoracic pressure regulation during cardiopulmonary resuscitation: A feasibility case-series

Aim of the study

Intrathoracic pressure regulation (IPR) is a novel, noninvasive therapy intended to increase cardiac output and blood pressure in hypotensive states by generating a negative end expiratory pressure of −12 cm H₂O between positive pressure ventilations. In this first feasibility case-series, we tested the hypothesis that IPR improves End tidal (ET) CO₂ during cardiopulmonary resuscitation (CPR). ETCO₂ was used as a surrogate measure for circulation.

Methods

All patients were treated initially with manual CPR and an impedance threshold device (ITD). When IPR-trained medics arrived on scene the ITD was removed and an IPR device (CirQLATOR™) was attached to the patient's advanced airway (intervention group). The IPR device lowered airway pressures to −9 mmHg after each positive pressure ventilation for the duration of the expiratory phase. ETCO₂, was measured using a capnometer incorporated into the defibrillator system (LifePak™). Values are expressed as mean ± SEM. Results were compared using paired and unpaired Student's t test. p values of <0.05 were considered statistically significant.

Results

ETCO₂ values in 11 patients in the case series were compared pre and during IPR therapy and also compared to 74 patients in the control group not treated with the new IPR device. ETCO₂ values increased from an average of 21 ± 1 mmHg immediately before IPR application to an average value of 32 ± 5 mmHg and to a maximum value of 45 ± 5 mmHg during IPR treatment (p < 0.001). In the control group ETCO₂ values did not change significantly. Return of spontaneous circulation (ROSC) rates were 46% (34/74) with standard CPR and ITD versus 73% (8/11) with standard CPR and the IPR device (p < 0.001).

Conclusions

ETCO₂ levels and ROSC rates were significantly higher in the study intervention group. These findings demonstrate that during CPR circulation may be significantly augmented by generation of a negative end expiratory pressure between each breath.     

Predicting the lack of ROSC during pre-hospital CPR: Should an end-tidal CO2 of 1.3 kPa be used as a cut-off value?

Aim

The aim of this study was to investigate if an initial ETCO₂ value at or below 1.3 kPa can be used as a cut-off value for whether return of spontaneous circulation during pre-hospital cardio-pulmonary resuscitation is achievable or not.

Materials and methods

We prospectively registered data according to the Utstein-style template for reporting data from pre-hospital advanced airway management from February 1st 2011 to October 31st 2012. Included were consecutive patients at all ages with pre-hospital cardiac arrest treated by eight anaesthesiologist-staffed pre-hospital critical care teams in the Central Denmark Region.

Results

We registered data from 595 cardiac arrest patients; in 60.2% (n = 358) of these cases the pre-hospital critical care teams performed pre-hospital advanced airway management beyond bag-mask ventilation. An initial end-tidal CO₂ measurement following pre-hospital advanced airway management were available in 75.7% (n = 271) of these 358 cases. We identified 22 patients, who had an initial end-tidal CO₂ at or below 1.3 kPa. Four of these patients achieved return of spontaneous circulation.

Conclusion

Our results indicates that an initial end-tidal CO₂ at or below 1.3 kPa during pre-hospital CPR should not be used as a cut-off value for the achievability of return of spontaneous circulation.     

Comparison of times of intervention during pediatric CPR maneuvers using ABC and CAB sequences: A randomized trial

Background

The proposed introduction of the CAB (circulation, airway, breathing) sequence for cardiopulmonary resuscitation has raised some perplexity within the pediatric community. We designed a randomized trial intended to verify if and how much timing of intervention in pediatric cardiopulmonary resuscitation is affected by the use of the CAB vs. the ABC (airway, breathing, circulation) sequence.

Patients and methods

340 volunteers, paired into 170 two-person teams, performed 2-rescuer healthcare provider BLS with both a CAB and ABC sequence. Their performances were audio–video recorded and times of intervention in the two scenarios, cardiac and respiratory arrest, were monitored.

Results

The CAB sequence compared to ABC prompts quicker recognition of respiratory (CAB vs. ABC = 17.48 ± 2.19 vs. 19.17 ± 2.38 s; p < 0.05) or cardiac arrest (CAB vs. ABC = 17.48 ± 2.19 vs. 41.67 ± 4.95; p < 0.05) and faster start of ventilatory maneuvers (CAB vs. ABC = 19.13 ± 1.47 s vs. 22.66 ± 3.07; p < 0.05) or chest compressions (CAB vs. ABC = 19.27 ± 2.64 vs. 43.40 ± 5.036; p < 0.05).

Conclusions

Compared to ABC the CAB sequence prompts shorter time of intervention both in diagnosing respiratory or cardiac arrest and in starting ventilation or chest compression. However, this does not necessarily entail prompter resumption of spontaneous circulation and significant reduction of neurological sequelae, an issue that requires further studies.     

Hemodynamic improvement of a LUCAS 2 automated device by addition of an impedance threshold device in a pig model of cardiac arrest

Introduction

The combination of the LUCAS 2 (L-CPR) automated CPR device and an impedance threshold device (ITD) has been widely implemented in the clinical field. This animal study tested the hypothesis that the addition of an ITD on L-CPR would enhance cerebral and coronary perfusion pressures.

Methods

Ten female pigs (39.0 ± 2.0 kg) were sedated, intubated, anesthetized with isofluorane, and paralyzed with succinylcholine (93.3 μg/kg/min) to inhibit the potential confounding effect of gasping. After 4 min of untreated ventricular fibrillation, 4 min of L-CPR + an active ITD or L-CPR + a sham ITD was initiated and followed by another 4 min of the alternative method of CPR. Systolic blood pressure (SBP), diastolic blood pressure (DBP), diastolic right atrial pressure (RAP), intracranial pressure (ICP), airway pressure, and end tidal CO₂ (ETCO₂) were recorded continuously. Data expressed as mean mmHg ± SD.

Results

Decompression phase airway pressure was significantly lower with L-CPR + active ITD versus L-CPR + sham ITD (−5.3 ± 2.2 vs. −0.5 ± 0.6; p < 0.001). L-CPR + active ITD treatment resulted in significantly improved hemodynamics versus L-CPR + sham ITD: ETCO₂, 35 ± 6 vs. 29 ± 7 (p = 0.015); SBP, 99 ± 9 vs. 93 ± 15 (p = 0.050); DBP, 24 ± 12 vs. 19 ± 15 (p = 0.006); coronary perfusion pressure, 29 ± 8 vs. 26 ± 7 (p = 0.004) and cerebral perfusion pressure, 24 ± 13 vs. 21 ± 12 (p = 0.028).

Conclusions

In pigs undergoing L-CPR the addition of the active ITD significantly reduced intrathoracic pressure and increased vital organ perfusion pressures.     

A comparison of paediatric airway anatomy with the SimBaby high-fidelity patient simulator

Background

The SimBaby high-fidelity patient simulator is a widely used paediatric simulator for the training of standard and critical airway management scenarios. Furthermore this simulator is frequently used for the evaluation of different airway devices and techniques. However, the anatomic structures of the SimBaby have not been compared to actual patients’ anatomy.

Methods

The CT radiographic measures of the upper airway anatomy of two SimBaby simulators were compared to MRI images of the upper airway of 20 children aged 1-11 months who underwent routine MRI scans under sedation for diagnostic purposes. Various distances of the tongue, soft palate and pharynx, cross sectional areas and volumes of anatomic structures of the upper airway including the retroglossal airspace were compared.

Results

The SimBaby's retroglossal airspace volume greatly differed from the measurements in patients (SimBaby 5.3 ± 0.4 vs. 1.9 ± 0.8 cm³ in infants, p < 0.01). Furthermore the distance from the alveolar process of the mandible to the posterior pharyngeal wall was larger in the SimBaby than in infants (5.8 ± 0.1 vs. 4.5 ± 0.5 cm, p < 0.001) and dimensions of the epiglottis and pharynx were larger in the Simbaby.

Conclusion

The anatomic features of the SimBaby do not adequately simulate the upper airway anatomy of infants. These results imply inadequate realism of this simulator for airway training and compromise the validity of comparative trials of different airway devices with the SimBaby as airway model.     

The Supreme Laryngeal Mask Airway™ (LMA): a new neonatal supraglottic device: comparison with Classic and ProSeal LMA in a manikin

Aim

The study aims to compare the performances (ease of insertion, time to establish effective ventilation and maximal inflation pressure) of classic™ (cLMA), ProSeal™ (PLMA) and Supreme™ (SLMA) Laryngeal Mask Airway when used in a neonatal airway management manikin by inexperienced delivery room trainees. The quality of the three devices, as perceived by participants, was also evaluated.

Methods

Health-care professional trainees were given a brief supervised training with the three devices. Every trainee was then observed positioning each of the three different LMAs in a single occasion. Success rate, time (IT) and maximal inflation pressure (PI_max) were recorded by a single unblinded observer. A 4-point scale was used to rate participants’ perceived quality.

Results

A total of 40 health-care professional trainees participated in the study.There were five, three and one failed insertions at the first attempt with the cLMA, PLMA and SLMA, respectively. No failures to establish an effective airway within three attempts were recorded. The success rate at first attempt was comparable among the three devices. The mean IT was significantly lower with the SLMA as compared with PLMA (p < 0.01), but not to cLMA. The mean PI_max was higher with SLMA than with cLMA and PLMA (p < 0.01). The ease of insertion as well as the effectiveness of ventilation were perceived by the participants as superior with SLMA as compared with cLMA and PLMA (p < 0.01).

Conclusions

Neonatal SLMA is superior to PLMA in terms of time to establish effective ventilation; furthermore, maximal inflation pressure and quality perceived by the operator are higher with neonatal SLMA than with cLMA and PLMA. These manikin data could provide a useful guide for planning potential future clinical research involving the newly developed supraglottic device in neonates.     

The use of the laryngeal tube disposable (LT-D) by paramedics during out-of-hospital resuscitation—An observational study concerning ERC guidelines 2005

Summary

In the current guidelines of the European Resuscitation Council (ERC), tracheal intubation, as an instrument for securing the airway during resuscitation, has become less important for persons not trained in this method. For those persons, different supraglottic airway devices are recommended by the ERC. The present investigation deals with the application of the laryngeal tube disposable (LT-D) during pre-hospital resuscitation by paramedics.

Methods

During a period of 2 years (2006–2008), we registered all cardiac arrest situations in which the LT-D had been applied according to the ERC guidelines 2005. Therefore, we investigated one emergency medical system in Germany.

Results

During the defined period, 92 resuscitation attempts, recorded on standardised data sheets, were included. The LT-D was used in 46% of all cardiac arrest situations. Overall, the LT-D was successfully inserted in more than 90% of all cases on first attempt. In 95% of all cases, no problems concerning ventilation of the patient were described.

Conclusion

As an alternative airway device recommended by the ERC in 2005, the LT-D may enable airway control rapidly and effectively. Additionally, by using the LT-D, a reduced “no-flow-time” and a better outcome may be possible.     

Performance of the i-gel™ during pre-hospital cardiopulmonary resuscitation

Background

Current cardiopulmonary resuscitation (CPR) guidelines recommend airway management and ventilation whilst minimising interruptions to chest compressions. We have assessed i-gel™ use during CPR.

Methods

In an observational study of i-gel™ use during CPR we assessed the ease of i-gel™ insertion, adequacy of ventilation, the presence of a leak during ventilation, and whether ventilation was possible without interrupting chest compressions.

Results

We analysed i-gel™ insertion by paramedics (n = 63) and emergency physicians (n = 7) in 70 pre-hospital CPR attempts. There was a 90% first attempt insertion success rate, 7% on the second attempt, and 3% on the third attempt. Insertion was reported as easy in 80% (n = 56), moderately difficult in 16% (n = 11), and difficult in 4% (n = 3). Providers reported no leak on ventilation in 80% (n = 56), a moderate leak in 17% (n = 12), and a major leak with no chest rise in 3% (n = 2). There was a significant association between ease of insertion and the quality of the seal (r = 0.99, p = 0.02). The i-gel™ enabled continuous chest compressions without pauses for ventilation in 74% (n = 52) of CPR attempts. There was no difference in the incidence of leaks on ventilation between patients having continuous chest compressions and patients who had pauses in chest compressions for ventilation (83% versus 72%, p = 0.33, 95% CI [−0.1282, 0.4037]). Ventilation during CPR was adequate during 96% of all CPR attempts.

Conclusions

The i-gel™ is an easy supraglottic airway device to insert and enables adequate ventilation during CPR.     

Influence of an impedance threshold valve on ventilation with supraglottic airway devices during cardiopulmonary resuscitation in a manikin

Aim This study investigates if a n impedance threshold valve (ITV) might improve survival after cardiac arrest by increasing vital organ blood flow. The combination of ITV and supraglottic airway devices (SADs) has not been previously studied. This simulation study in a manikin aimed at analysing differences in ventilation with different SADs without and with an ITV.

Methods

In a resuscitation manikin, cardiopulmonary resuscitation (CPR) was performed with interrupted (30:2) and continuous chest compressions using facemask, tracheal tube and 10 SADs (six different laryngeal masks, LT-D, LTS-D, Combitube^® and Easy Tube^®). Ventilation was performed with and without an ITV. A total of 550 CPR cycles of 3-min duration were performed with chest compressions and ventilation standardised by use of a mechanical thumper device and an emergency ventilator.

Results

Sufficient ventilation was possible with all devices tested. For ventilation during continuous chest compressions, there were significantly reduced tidal volumes for all airway devices with ITV use. By contrast, during interrupted chest compressions, no differences in tidal volumes with the ITV occurred in the majority of devices. The maximum reduction of tidal volume for any device was 7.8% of the volume reached without the ITV.

Conclusion

Based on the findings of this manikin trial, the use of an ITV for ventilation during CPR is possible in combination with supraglottic airway devices. Merging these two strategies warrants further clinical evaluation to judge the relevance of tidal volume reduction found in this trial.     

The impact of airway management on quality of cardiopulmonary resuscitation: An observational study in patients during cardiac arrest

Background

Minimising interruptions in chest compressions is associated with improved survival from cardiac arrest. Current in-hospital guidelines recommend continuous chest compressions after the airway is secured on the premise that this will reduce no flow time. The aim of this study was to determine the effect of advanced airway use on the no flow ratio and other measures of CPR quality.

Methods

Consecutive adult patients who sustained an in-hospital cardiac arrest were enrolled in this prospective observational study. The quality of CPR was measured using the Q-CPR device (Phillips, UK) before and after an advanced airway device (endotracheal tube [ET] or laryngeal mask airway [LMA]) was inserted. Patients receiving only bag-mask ventilation were used as the control cohort. The primary outcome was no flow ratio (NFR). Secondary outcomes were chest compression rate, depth, compressions too shallow, compressions with leaning, ventilation rate, inflation time, change in impedance and time required to successfully insert airway device.

Results

One hundred patients were enrolled in the study (2008–2011). Endotracheal tube and LMA placement took similar durations (median 15.8 s (IQR 6.8–19.4) vs LMA median 8.0 s (IQR 5.5–15.9), p = 0.1). The use of an advanced airway was associated with improved no flow ratios (endotracheal tube placement (n = 50) improved NFR from baseline median 0.24 IQR 0.17–0.40) to 0.15 to (IQR 0.09–0.28), p = 0.012; LMA (n = 25) from median 0.28 (IQR 0.23–0.40) to 0.13 (IQR 0.11– 0.19), p = 0.0001). There was no change in NFR in patients managed solely with bag valve mask (BVM) (n = 25) (median 0.29 (IQR 0.18–0.59) vs median 0.26 (IQR 0.12–0.37), p = 0.888). There was no significant difference in time taken to successfully insert the airway device between the two groups.

Conclusion

The use of an advanced airway (ETT or LMA) during in-hospital cardiac arrest was associated with improved no flow ratio. Further studies are required to determine the effect of airway devices on overall patient outcomes.     

Pedi-cap color change precedes a significant increase in heart rate during neonatal resuscitation

Introduction

Heart rate is the most important indicator of infant well-being during neonatal resuscitation. The Nellcor Pedi-Cap turns gold when exposed to exhaled gas with CO₂ > 15 mmHg. The aim of this study was to determine if Pedi-Cap gold color change during neonatal resuscitation precedes an increase in heart rate in babies with bradycardia receiving mask ventilation.

Methods

This was a single-center retrospective review of video recordings and physiologic data of newborns with bradycardia receiving mask positive pressure ventilation during neonatal resuscitation. Subjects were included if the baby's HR < 100 BPM within the first 90 s of resuscitation. The primary outcome was the change in HR prior to Pedi-Cap gold color change compared to the HR after Pedi-Cap gold color change.

Results

Forty-one newborns during the study period had HR < 100 BPM and received mask positive pressure ventilation with a Pedi-Cap. The median heart rate 10 s prior to Pedi-Cap gold color change was 75 BPM (IQR 62–85) and increased to 136 BPM (IQR 113–158) 30 s after gold color change (p < 0.001). SpO₂ increased from 45 ± 17% prior to Pedi-Cap gold color change to 52 ± 17% 30 s after gold color change (p = 0.001).

Conclusions

Colorimetric CO₂ detection during mask positive pressure ventilation in neonatal resuscitation precedes a significant increase in heart rate and SpO₂. The Pedi-Cap can be easily applied during resuscitation, requires no electricity, provides immediate feedback and may be a useful, simple tool early in resuscitation and may be especially useful in resource limited settings.     

Mild hypothermia reduces per-ischemic reactive oxygen species production and preserves mitochondrial respiratory complexes

Background

Mitochondrial dysfunction is critical following ischemic disorders. Our goal was to determine whether mild hypothermia could limit this dysfunction through per-ischemic inhibition of reactive oxygen species (ROS) generation.

Methods

First, ROS production was evaluated during simulated ischemia in an vitro model of isolated rat cardiomyocytes at hypothermic (32 °C) vs. normothermic (38 °C) temperatures. Second, we deciphered the direct effect of hypothermia on mitochondrial respiration and ROS production in oxygenated mitochondria isolated from rabbit hearts. Third, we investigated these parameters in cardiac mitochondria extracted after 30-min of coronary artery occlusion (CAO) under normothermic conditions (CAO-N) or with hypothermia induced by liquid ventilation (CAO-H; target temperature: 32 °C).

Results

In isolated rat cardiomyocytes, per-ischemic ROS generation was dramatically decreased at 32 vs. 38 °C (e.g., −55 ± 8% after 140 min of hypoxia). In oxygenated mitochondria isolated from intact rabbit hearts, hypothermia also improved respiratory control ratio (+22 ± 3%) and reduced H₂O₂ production (−41 ± 1%). Decreased oxidative stress was further observed in rabbit hearts submitted to hypothermic vs. normothermic ischemia (CAO-H vs. CAO-N), using thiobarbituric acid-reactive substances as a marker. This was accompanied by a preservation of the respiratory control ratio as well as the activity of complexes I, II and III in cardiac mitochondria.

Conclusion

The cardioprotective effect of mild hypothermia involves a direct effect on per-ischemic ROS generation and results in preservation of mitochondrial function. This might explain why the benefit afforded by hypothermia during regional myocardial ischemia depends on how fast it is instituted during the ischemic process.