Needle cricothyroidotomy

Use of a trans-tracheal rapid insufflation of oxygen device in a "cannot intubate, cannot oxygenate" scenario in a parturient -a case report

Background

The trans-tracheal rapid insufflation of oxygen (TRIO) device is less commonly used and is an alternative to trans-tracheal jet ventilation for maintaining oxygenation in a "cannot intubate, cannot oxygenate" (CICO) scenario.

Case

We report the successful use of this device to maintain oxygenation after jet ventilator failure in a parturient who presented with the CICO scenario during the procedure for excision of laryngeal papilloma.

Conclusions

A stepwise approach to the airway plan and preparation for an event of failure is essential for good materno-fetal outcomes. The TRIO device may result in inadequate ventilation that can lead to hypercarbia and respiratory acidosis. Hence, it should only be used as a temporizing measure before a definitive airway can be secured.

Percutaneous Transtracheal Jet Ventilation with Various Upper Airway Obstruction

A "cannot-ventilate, cannot-intubate" situation is critical. In difficult airway management, transtracheal jet ventilation (TTJV) has been recommended as an invasive procedure, but specialized equipment is required. However, the influence of upper airway resistance (UAR) during TTJV has not been clarified. The aim of this study was to compare TTJV using a manual jet ventilator (MJV) and the oxygen flush device of the anesthetic machine (AM). We made a model lung offering variable UAR by adjustment of tracheal tube size that can ventilate through a 14-G cannula. We measured side flow due to the Venturi effect during TTJV, inspired tidal volume (TVi), and expiratory time under various inspiratory times. No Venturi effect was detected during TTJV with either device. With the MJV, TVi tended to increase in proportion to UAR. With AM, significant variations in TVi was not detected with changes in any UAR. In conclusion, UAR influenced forward flow of TTJV in the model lung. The influence of choked flow from the Venturi effect was minimal under all UAR settings with the MJV, but the AM could not deliver sufficient flow.

Rescue ventilation through a small-bore transtracheal cannula in severe hypoxic pigs using expiratory ventilation assistance

BACKGROUND

Suction-generated expiratory ventilation assistance (EVA) has been proposed as a way to facilitate bidirectional ventilation through a small-bore transtracheal cannula (TC). In this study, we investigated the efficiency of ventilation with EVA for restoring oxygenation and ventilation in a pig model of acute hypoxia.

METHODS

Six pigs (61-76 kg) were anesthetized and ventilated (intermittent positive pressure ventilation) via a cuffed endotracheal tube (ETT). Monitoring lines were placed, and a 75-mm long, 2-mm inner diameter TC was inserted. After the baseline recordings, the ventilator was disconnected. After 2 minutes of apnea, reoxygenation with EVA was initiated through the TC and continued for 15 minutes with the ETT occluded. In the second part of the study, the experiment was repeated with the ETT either partially obstructed or left open. Airway pressures and hemodynamic data were recorded, and arterial blood gases were measured. Descriptive statistical analysis was performed.

RESULTS

With a completely or partially obstructed upper airway, ventilation with EVA restored oxygenation to baseline levels in all animals within 20 seconds. In a completely obstructed airway, PaCO2 remained stable for 15 minutes. At lesser degrees of airway obstruction, the time to reoxygenation was delayed. Efficacy probably was limited when the airway was completely unobstructed, with 2 of 6 animals having a PaO2 <85 mm Hg even after 15 minutes of ventilation with EVA and a mean PaCO2 increased up to 90 mm Hg.

CONCLUSIONS

In severe hypoxic pigs, ventilation with EVA restored oxygenation quickly in case of a completely or partially obstructed upper airway. Reoxygenation and ventilation were less efficient when the upper airway was completely unobstructed.

Macroscopic barotrauma caused by stiff and soft-tipped airway exchange catheters: an in vitro case series

BACKGROUND

Many airway management guidelines include the use of airway exchange catheters (AECs). There are reports, however, of harm from their use, from both malpositioning and in particular from the administration of oxygen via an AEC leading to barotrauma.

METHODS

We used an in vitro pig lung model to investigate the safety of administering oxygen at 4 different flow rates from a high-pressure source via 2 different AECs: a standard catheter and a soft-tipped catheter. Experiments were performed with the catheters positioned either above the carina or below it at the first point of resistance to advancement (hold-up). The experiments were then repeated to produce a series of 32 cases.

RESULTS

With an AEC positioned above the carina, we did not observe macroscopic lung damage after the administration of oxygen. The administration of oxygen through an AEC positioned below the carina resulted in macroscopic barotrauma regardless of the rate of oxygen delivery. Increasing speed of oxygen flow led to faster and more extensive damage. Use of an "injector" at 2.5 or 4 bar led to instantaneous macroscopic lung damage and advancement of the AEC through the lung tissue. Our observations were the same when both types of AECs were used.

CONCLUSIONS

Our results are consistent with reports of harm during the use of AECs and demonstrate the risk of administering oxygen through these devices when they are positioned below the carina. An indicator, ideally made on an AEC at the time of manufacture and designed to lie at the same level as the teeth, may be useful in preventing the insertion of that AEC beyond the level of the carina and improve the safety of using such devices.

Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2: intensive care and emergency departments

BACKGROUND

The Fourth National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society (NAP4) was designed to identify and study serious airway complications occurring during anaesthesia, in intensive care unit (ICU) and the emergency department (ED).

METHODS

Reports of major complications of airway management (death, brain damage, emergency surgical airway, unanticipated ICU admission, prolonged ICU stay) were collected from all National Health Service hospitals over a period of 1 yr. An expert panel reviewed inclusion criteria, outcome, and airway management.

RESULTS

A total of 184 events met inclusion criteria: 36 in ICU and 15 in the ED. In ICU, 61% of events led to death or persistent neurological injury, and 31% in the ED. Airway events in ICU and the ED were more likely than those during anaesthesia to occur out-of-hours, be managed by doctors with less anaesthetic experience and lead to permanent harm. Failure to use capnography contributed to 74% of cases of death or persistent neurological injury.

CONCLUSIONS

At least one in four major airway events in a hospital are likely to occur in ICU or the ED. The outcome of these events is particularly adverse. Analysis of the cases has identified repeated gaps in care that include: poor identification of at-risk patients, poor or incomplete planning, inadequate provision of skilled staff and equipment to manage these events successfully, delayed recognition of events, and failed rescue due to lack of or failure of interpretation of capnography. The project findings suggest avoidable deaths due to airway complications occur in ICU and the ED.

Equipment to manage a difficult airway during anaesthesia

Airway complications are a leading cause of morbidity and mortality in anaesthesia. Effective management of a difficult airway requires the timely availability of suitable airway equipment. The Australian and New Zealand College of Anaesthetists has recently developed guidelines for the minimum set of equipment needed for the effective management of an unexpected difficult airway (TG4 [2010] www.anzca.edu.au/resources/professionaldocuments). TG4 [2010] is based on expert consensus, underpinned by wide consultation and an extensive review of the available evidence, which is summarised in a Background Paper (TG4 BP [2010] www.anzca.edu.au/ resources/professional-documents). TG4 [2010] will be reviewed at the end of one year and thereafter every five years or more frequently if necessary. The current paper is reproduced directly from the Background Paper (TG4 BP [2010]).

Pediatric transtracheal and cricothyrotomy airway devices for emergency use: which are appropriate for infants and children?

Cricothyrotomy or insertion of a transtracheal device is a life-saving maneuver that may be performed on an emergent or semi-elective basis as a means of bypassing an obstructed upper airway. A surgeon is trained to perform this life-saving procedure whereas most anesthesiologists are not facile with the scalpel. It is for this reason that many percutaneous devices have been developed for use by surgeons and nonsurgeons alike. Unfortunately, the majority of such devices are designed for use in adults and/or teenagers but are not appropriate for neonates and infants. The unique anatomy of the infant larynx, the small size of the cricothyroid membrane, and the technical difficulty of locating the correct anatomical structures make the use of most of these devices impractical if not outright dangerous in neonates and infants. This paper will review many (but not all) of the available devices, associated literature, pitfalls and dangers. It is emphasized that each clinician should become familiar with the advantages and disadvantages of these devices and obtain training with simulators or animal models. A strategy for management of the 'cannot ventilate, cannot oxygenate, cannot intubate' situation should be developed with age and size appropriate equipment.

Experimental adaptation of the Enk oxygen flow modulator for potential pediatric use

AIM

A bench study of the Enk oxygen flow modulator (Enk OFM) was conducted to test its performance and potential use in pediatric patients using the Advanced Paediatric Life Support (APLS) guidelines (Advanced Paediatric Life Support, 2005: 224).

BACKGROUND

The Enk OFM is a preassembled emergency transtracheal ventilation device.

METHODS

The Enk OFM was connected to two sources of oxygen: first, to a Precision Medical flowmeter and second, to an Aestiva anesthetic machine axillary flowmeter. Testing was performed on standard cannulae of 20, 18, and 16 gauge caliber and also a 7.5 cm 15G Emergency Transtracheal Airway Catheter (Cook Medical). Serial hole occlusion of the Enk OFM was applied and the resulting flow rates were measured by a RespiCal Timeter.

RESULTS

Oxygen flow was best controlled by occluding all holes of the Enk OFM and incrementally increasing oxygen flow by the flowmeter with an initial setting of 1 l min(-1) year(-1) of age. Contrary to the original description of this device (Anesth Analg 1998; 86: 203S), sequential occlusion of the five side holes does not lead to a significant exponential increase in gas flow. Incomplete occlusion of the Enk OFM provided insufficient and unpredictable flow.

CONCLUSIONS

The Enk OFM should be fully occluded for inspiration with flow rates set at 1 l min(-1) year(-1) of age and adjusted to effect. These flow rates are consistent with the APLS recommendations. Flows above 15 l min(-1) are potentially dangerous and the Enk OFM fails to perform as an on-off device. Flowmeter settings of <1 l min(-1) risk no flow. Cannulae of at least 18G should be used for optimal flow.

Techniques for emergency ventilation through a needle cricothyroidotomy

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 x min(-1) mark (44.5 vs 15.8 l x min(-1), respectively; p < 0.0001). 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 x min(-1) mark (285.3 vs 66.4 kPa, respectively; p < 0.0001). 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.