The use of bromothymol blue and sodium thiopentone to confirm tracheal intubation

Confirmation of correct tracheal tube placement in newborn infants

Colorimetric capnography, a new procedure to ensure correct feeding tube placement in the intensive care unit: An evaluation of a local protocol

Resuscitation highlights in 2011

Waveform capnography use has been incorporated into guidelines for the confirmation of tracheal intubation. We aim to describe the trend in waveform capnography use in emergency departments and PICUs and assess the association between waveform capnography use and adverse tracheal intubation-associated events. A multicenter retrospective cohort study. Thirty-four hospitals (34 ICUs and nine emergency departments) in the National Emergency Airway Registry for Children quality improvement initiative. Primary tracheal intubation in children younger than 18 years. None. Patient, provider, and practice data for tracheal intubation procedure including a type of end-tidal carbon dioxide measurement, as well as the procedural safety outcomes, were prospectively collected. The use of waveform capnography versus colorimetry was evaluated in association with esophageal intubation with delayed recognition, cardiac arrest, and oxygen desaturation less than 80%. During January 2011 and December 2015, 9,639 tracheal intubations were reported. Waveform capnography use increased over time (39% in 2010 to 53% in 2015; p < 0.001), whereas colorimetry use decreased (< 0.001). There was significant variability in waveform capnography use across institutions (median 49%; interquartile range, 25-85%; p < 0.001). Capnography was used more often in emergency departments as compared with ICUs (66% vs. 49%; p < 0.001). The rate of esophageal intubation with delayed recognition was similar with waveform capnography versus colorimetry (0.39% vs. 0.46%; p = 0.62). The rate of cardiac arrest was also similar (p = 0.49). Oxygen desaturation occurred less frequently when capnography was used (17% vs. 19%; p = 0.03); however, this was not significant after adjusting for patient and provider characteristics. Significant variations existed in capnography use across institutions, with the use increasing over time in both emergency departments and ICUs. The use of capnography during intubation was not associated with esophageal intubation with delayed recognition or the occurrence of cardiac arrest.

Use of Tube Condensation as an Indicator of Endotracheal Tube Placement

The chemical and physical stability of propranolol HCl in six extemporaneously prepared paediatric formulations was studied under accelerated temperature and light conditions. A preliminary study was carried out to find the solubility of propranolol HCl (pure and crushed Inderal 40mg tablets) in the different vehicles at 4 oC, 25 oC, and 40 oC after one and six hours. The study indicated that the pure propranolol HCl powder was 100% soluble in all but one vehicle, however, only 90.25% was extracted from crushed Inderal tablets by these vehicles at 25 oC. The amount of propranolol HCl extracted from crushed Inderal 40mg tablets was determined mainly by the pH of the vehicle. It is suggested that the propranolol HCl is binding to calcium carboxymethylcellulose a tablet excipient in Inderal 40mg since complete extraction was achieved from another commercial tablet (Cardinol 40mg) which does not contain this excipient. A preliminary binding study using ultrafiltration demonstrated binding between propranolol HCl and sodium carboxymethylcellulose. (1) Stability study The stability trial was performed at 4 ±1.0 oC, 30 ±0 .5 oC and 50 ±1 .0 oC. Formulas were stored in amber bottles and sampled at zero, 1, 2, 4, 8 and 12 weeks. Chemical stability was determined by high performance liquid chromatography which was developed for propranolol HCl and preservatives (methyl hydroxybenzoate, propyl hydroxybenzoate and sodium benzoate). The physical study monitored pH, viscosity and the colour changes as well as the redispersibility and caking of the formulations. The study showed that propranolol HCl was stable over 12 weeks at all temperatures tested. However, some formulations showed some physical changes, i.e. colour changes, fungal growth, moderate caking, precipitate formation in a clear solution formula, and a complex formation between propranolol HCl and sodium carboxymethylcellulose. The amount of propranolol HCl in the supernatant at zero time was of 77.4-100% range and it was pH dependent. (2) Accelerated light study The light stability trial was performed by storing the formulations in a light cabinet in clear and amber bottles at controlled temperature (30 ±10 oC). Each formulation was stored at four incident light intensities over range 0-1.96mW/cm2. Samples were taken at zero, 1, 2, 4 and 8 weeks for chemical and physic al assay. High performance liquid chromatography was used for the chemical assay for the propranolol HCl and the preservatives. The physical study included the pH and colour changes. The study indicated that propranolol HCl is unstable at high light intensities in all formulations in both clear and amber bottles. The degree of decomposition was dependant mainly on the type of formulation, i.e. a formulation with low propranolol HCl concentration showed a higher degradation than with high propranolol HCl concentration. Also it was incident light intensity dependant. Colour and pH changes accompanied the degradation process, but there was no direct relationship between these changes and the degree of decomposition .

To evaluate the ability of a disposable, colorimetric end-tidal CO2 detector to verify proper endotracheal (ET) tube placement in out-of-hospital cardiac arrest, and to correlate semiquantitative CO2 measurements with the rate of return of spontaneous circulation (ROSC). Prospective, observational study using a convenience sample of intubated out-of-hospital cardiac arrest patients. A disposable, colorimetric end-tidal CO2 detector was attached to the ET tube after intubation. In the absence of a colorimetric change, the paramedics reassessed the tube placement and could reintubate the patient. Tube placement was verified at the hospital. Paramedics were instructed to contact the base station and report the colorimetric change upon hospital arrival. ROSC was defined as restoration of a self-sustaining pulse until hospital arrival. Between December 1990 and May 1993, ET tubes were placed in 566 victims of out-of-hospital cardiac arrest. 541 of the 566 intubations (95.6%) were associated with a color change. In one case with a color change and out-of-hospital clinical evidence of proper tube placement, the tube was determined to be in the esophagus at the hospital. Correct placement of the remaining 565 of 566 (99.8%) tubes was verified. Of the 566 patients who had a colorimetric change, 91 (16%) had ROSC vs one of 25 (4%) patients who did not have a color change. In one subgroup (n = 179), the degree of color change was highly associated with ROSC (p = 0.004). A disposable, colorimetric end-tidal CO2 detector appears reliable in verifying proper ET tube placement in victims of out-of-hospital cardiac arrest. The degree of color change correlates with the probability of ROSC.

Tracheal intubation is older than the recognized his-tory of general anesthesia itself. In the late 18th cen-tury, The Royal Humane Society of London used tra-cheal intubation for resuscitating the near-drowned.Approximately 100 years later, MacEwan (1) per-formed a digital tracheal intubation in an awake pa-tient before a chloroform and air general endotrachealanesthetic for the resection of a tongue tumor, and in1928, Magill (2) incorporated blind nasal tracheal in-tubation as a part of a general anesthetic. Althoughlaryngoscopes were invented in the 19th century, tra-cheal intubation under direct visualization was greatlyenhanced by the development of a special laryngo-scope blade by Macintosh (3) in 1943.The first reported use of a lighted stylet used tofacilitate intubation came in 1957 when (by now SirRobert) Macintosh (4) described an 18-inch illumi-nated tracheal tube introducer, which was designed tostiffen the tube and better illuminate the cords bysupplementing the light of the laryngoscope. Berman(5) described a similar device in 1959 and said it wasuseful “when the fickle light of the laryngoscope hasgone out at the most inopportune time.” In the sameyear, Yamamura et al. (6) described a light bulb-tippedwire that was inserted into the tracheal tube beforeblind nasal intubation in awake patients. The tubeposition was then determined by the medial transillu-mination of the external throat and neck.In 1977, Foster (7) used a transilluminating fiberop-tic bundle to facilitate tracheal intubation in a youngchild with trismus, and Ducrow (8), in the followingyear, used a flexible surgical light (Flexi-lum™, Con-cept Corporation, Clearwater, FL) to achieve the sameend by first passing a guide (two plastic suction cath-eters connected end-to-end) into the trachea followedby passage of the tracheal tube over the guide. In acorrespondence to the latter article, Rayburn (9) com-mented that the Flexi-lum™ could be positioned in-side the tracheal tube, thereby shortening the intuba-tion sequence and claimed that the technique,nicknamed “lightwand intubation,” had been used forsome years at the Brooke Army Medical Center.

Introduction: In pediatric critical care, accurate placement of endotracheal tubes prevent unplanned extubation or unrecognized bronchial intubation. The optimal position of the endotracheal tube is believed to be 2.0 cm above the carina so that movement of the head does not raise the ETT out of the airway nor push it in to an endobronchial position. The gold standard for confirmation has been the chest radiograph. To reduce exposure to radiation, and ensure optimal position immediately after extubation, non-radiographic techniques to determine optimal placement have included formulas based on body size, ETT size, gestational age, and measured markings on the end of the endotracheal tube. Formulas that relate the length of the trachea to variables such as age, weight, or height are inconsistent, and may be less accurate for children with obesity, failure to thrive, or scoliosis which affect height. Ulnar length is preserved in these populations, and is unaffected by body habitus or neuromuscular disease. Hypothesis: Ulnar length can be used to determine the optimal depth of oro-tracheal intubation. Methods: Any orotracheally intubated child admitted to the pediatric or cardiothoracic intensive care unit was eligible. Routinely obtained chest radiographs were used to determine endotracheal tube position and distance from the carina. The patient’s ulnar length, height, and depth of endotracheal tube insertion were obtained. Optimal endotracheal tube position, calculated as 2 cm above the carina was measured based on current tube position. Ideal ETT depth was plotted against the patient’s ulnar length, and linear regression was used to determine a predictive equation. Results: 58 patients were included. Optimal depth of the endotracheal tube plotted against ulnar length resulted in a linear relationship, given by the following formula: depth of ETT insertion in cm = 0.72(ulnar length in cm) + 5.2 (R2 = 0.84). Conclusions: Optimal depth of endotracheal tube insertion can be rapidly estimated using ulnar length. This information can be used to ensure correct endotracheal tube placement, potentially reducing the need for chest radiographs.

BackgroundIntubation and maintaining airway are crucial in the management of critically ill patients in the emergency department. Correct tracheal intubation should be confirmed by the physician, otherwise oesophageal intubation could lead to hypoxia with detrimental consequences and even death. Sonography can be used to determine proper placement of the tracheal tube.MethodsIn this study, 75 patients, with an indication of intubation and age older than 18 years entered the study. An emergency medicine performed real-time sonography of the trachea to evaluate the correct placement of endotracheal tube. Tube passage (snowstorm) and vocal cord angel widening (bullet sign) were evaluated, and then both lungs sliding and diaphragm movement were evaluated to confirm correct tube placement and ventilation.ResultsIn this study, 75 patients entered the study. The mean age of the patients was 61.12; 47 patients (62.7%) were male and 28 (37.3%) were female. The reason of intubation was the decreased level of consciousness in 22 cases (29.3%), cardiopulmonary arrest in 22 patients (29.3%), respiratory distress in 9 patients (12%), shock in 10 patients (13.3%), and seizure in 1 case. Snowstorm sign was seen in 72 patients (96%). Bullet sign was objected in 24 cases (32%). Lung sliding was seen bilaterally in 63 patients (84%) and unilaterally in 7 patients (9.3 %), but it was not noticed in 6.7% of the patients (5 patients).ConclusionsTransverse tracheal and lung sonography in the emergency department can be a fast measure to confirm correct endotracheal intubation.

Aims NICE provide clear guidelines on confirming correct nasogastric (NG) tube siting using pH testing of aspirates or with X-rays where indeterminate samples are drawn. We aimed to audit documentation following nasogastric tube insertion to ascertain adherence to NICE guidelines. Methods A single-cycle snapshot audit was conducted on all surgical inpatients who had nasogastric tubes inserted over their admission across a single-centre district general hospital general surgery department. Data was collected on indication for NG tube insertion (drainage or feeding), length of initial tube insertion, whether pH testing was used to confirm position, and whether correct tube placement has been confirmed by a competent person through x-ray where indeterminate samples were tested from NG aspirate (pH &amp;gt; 5.5). Results A total of 15 patients had an NG tube inserted over their admission with mean age 77.3 years (range 47-97). 60% of patients had correctly documented confirmation of NG tube siting. 4/15 NG tubes were inserted for feeding purposes (26.7%), all of which were documented correctly. Only 45.5% of NG tubes for drainage were documented correctly and only 33.3% of all NG tubes had length of insertion documented. Where pH testing was inconclusive, a chest X-ray was requested for all patients and sufficiently documented by a doctor qualified to confirm position. No complications relating to NG tubes occurred across the audit study. Conclusions Implementation of improvement measures are warranted to improve overall adherence with NICE guidelines and prevent risk of incorrect confirmation of NG tube siting.

We read with interest the recent article by Dr. Hunyady and colleagues.1While we acknowledge that mathematical formulae based on morphometric data may be useful guides, we caution against applying these formulae in lieu of clinical assessment. We conducted a randomized clinical trial to compare three common methods of endotracheal tube (ETT) placement: 1) deliberate mainstem intubation with subsequent withdrawal of the ETT 2 cm above the carina (“mainstem” method); 2) alignment of the double black line marker near the ETT tip at the vocal cords (“marker” method); or 3) placement of the ETT at a depth determined by the formula: ETT depth (cm) = 3 times ETT size (mmID) (“formula” method).2In our study, the formula method only placed the ETT at the appropriate depth 42% of the time. In addition, we retrospectively evaluated the efficacy of another formula, ETT depth (cm) = Age(yrs)/2 + 12,3but appropriate placement would have been achieved only 42% of the time as well. Identification of the carina via auscultation, the mainstem method, was the preferred technique (73%, P = 0.006 vs. the formula method).2Although our study did not specifically examine the efficacy of the Morgan and Steward formula,4neither did the study by Hunyady et al. 1The authors’ conclusion that the “.t.t.tMorgan formula provides good guidance for intubation in children .t.t.” is extrapolated based on their measurements and calculations.1The authors do not specify which technique was used to initially determine ETT depth in their study subjects or report the rates of correct versus incorrect placement for the actual placement methods used. Based on the estimates by Hunyady et al. , the Morgan and Steward formula would have placed the ETT tip on average at the 90thpercentile for front teeth-to-carina distance and < 0.5 cm from the carina in 13 of their youngest subjects.1This is concerning since, as the authors astutely point out, the ETT is subject to movement with neck flexion or extension which may result in inadvertent endobronchial ETT placement.5–7Auscultation methods have their limitations as well,2,3and no clinical technique results in 100% success. When ETT placement is in question or when accurate ETT depth is mandatory for a particular surgical procedure (i.e. , prone position or head and neck surgery), we recommend intraoperative chest radiography, fluoroscopy, or fiberoptic bronchoscopy.*University of California, San Diego Medical Center, San Diego, California. ermariano@ucsd.edu

Background: Preservation of patient’s spontaneous respiration and consciousness are most important recommendations in any one of difficult airway. Under adequate upper airway block, awake intubation could be performed through oral or nasal routes using fibre optic visualization or blind nasal techniques. This work was designed to compare the applicability of awake blind nasal intubation and that of fibre optic naso-trachael intubation. Materials and Methods: Sixty patients were distributed randomly into two groups of thirty patients each, Group A (fibre optic intubation) and Group B (Blind nasal intubation) After pre-operative evaluation, patients in both the groups were given lidocaine nebulisation 4% (5ml) and bilateral SLN and RLN blocks. Patients were intubated with fibre optic and blind nasal intubation techniques according to their groups. Tube placement in trachea was confirmed by ETCO2. In both the groups, comparison regarding time taken for intubation, no of attempts of intubation, hemodynamic changes and side effects / complications were done. Results: Intubation time in group A was significantly less than that of group B. (P<0.05). Intubation under first attempt was significantly higher in group A than group B. Haemo-dynamic parameters were also comparable. No major side effects/complications were observed. Conclusion: We concluded that, both blind nasal and fibre optic tracheal intubation are of gold standard in patients with no or reduced mouth opening. However fibre optic nasal intubation requires less time and less number of attempts for intubation with minimal haemodynamic changes and have low incidences of complications.

The impact of UV radiation on the change of colour and composition of the surface of lime wood treated with a CO2 laser

Although furfurylation greatly improves dimensional stability, hardness, and biodegradation resistance of wood and bamboo, the effects of furfurylation on the resistance of wood and bamboo to weathering are still not clear. In this study, poplar wood and moso bamboo were furfurylated and underwent artificial weathering. The surface chemical changes of the control and furfurylated wood and bamboo samples were examined using the attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The colour changes were also investigated by measuring CIELab parameters. Results demonstrated that the wood/bamboo surfaces showed decreased lightness and became reddish and yellowish after artificial weathering. Furfurylation endowed poplar wood and bamboo with improved stability of photo-discolouration. Weathering caused remarkable degradation of lignin in the control and furfurylated sample surfaces with decreased aromatic carbons and increased oxygenated carbons. The poly(furfuryl alcohol) in sample surfaces could also be oxidized during weathering. Compared with the furfurylated bamboo, the furfurylated poplar wood had higher stability of photo-degradation.