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Cochrane Database of Systematic Reviews Protocol - Intervention

Assessment of techniques to ascertain correct endotracheal tube placement in neonates

Authors' declarations of interest

Version published: 14 November 2012 Version history

https://doi.org/10.1002/14651858.CD010221

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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To compare two‐view chest radiogram (control) versus various techniques (intervention) for identification of correct tube placement after oral or nasal intubation in newborn infants in either the delivery room or neonatal intensive care unit.

  • Two‐view chest radiogram (control) versus clinical assessment (intervention).

  • Two‐view chest radiogram (control) versus exhaled CO2 (intervention).

  • Two‐view chest radiogram (control) versus respiratory function monitoring (intervention).

Subgroup analysis will be performed to determine whether the safety and efficacy vary according to:

  • postmenstrual age: Term (37 weeks’ postmenstrual age and above) versus preterm between 29 and 36 weeks versus preterm < 29 weeks infants;

  • type of clinical assessment (heart rate versus adequate chest wall movements versus confirmation of position by direct laryngoscopy versus observation of ETT passage through the vocal cords versus presence of breath sounds in the axilla and absence of breath sounds in the epigastrium versus condensation in the ETT during ventilation);

  • type of exhaled CO2 monitoring (semi‐quantitative colorimetric versus main stream versus side stream versus micro stream CO2‐detectors);

  • type of respiratory function monitor;

  • skill level of operator (< 1 year; 2 to 5 years; > 5 to 10 years; > 10 years);

  • discipline of operator (Medical, Nursing, Respiratory Therapist).

Background

Description of the condition

Endotracheal intubation remains a common procedure in the delivery room and the neonatal intensive care unit (Roberts 1995; Falck 2003; Leone 2005; O'Donnell 2006). However, the success rate of correct endotracheal tube (ETT) placement for junior medical staff is less than 50% and accidental oesophageal intubation is common (Roberts 1995; Falck 2003; Leone 2005; O'Donnell 2006; Schmölzer 2011). An international consensus statement on neonatal resuscitation recommends that tube placement should be confirmed by observation of clinical signs and detection of exhaled carbon dioxide (CO2) (Kattwinkel 2010). Clinical signs for sufficient tube placement include a prompt increase in heart rate, adequate chest wall movements, and confirmation of position by direct laryngoscopy, the observation of ETT passage through the vocal cords, presence of breath sounds in the axilla and absence of such in the epigastrium and condensation in the ETT during ventilation (Kattwinkel 2010). However, these indicators are subjective and can be misleading even in experienced hands (Birmingham 1986). Recognising that the ETT is in the oesophagus, using clinical assessment alone, can take several minutes (Roberts 1995; Aziz 1999; Repetto 2001; O'Donnell 2006).

Description of the intervention

Clinical signs

Clinical signs of correct ETT placement include prompt increase in heart rate, adequate chest wall movements, confirmation of position by direct laryngoscopy, observation of ETT passage through the vocal cords, presence of breath sounds in the axilla and absence of breath sounds in the epigastrium and condensation in the ETT during ventilation (Kattwinkel 2010). We plan to include studies evaluating any of the clinical signs used to confirm correct tube placement.

Chest X‐ray

Harris 2008 studied the value of fluoroscopic tube placement in a neonatal to paediatric population of 267 children (aged 12 days to 12 years). According to the authors, 18% of all ETT were incorrectly placed upon the first intubation attempt. Worryingly, 37% of all intubated neonates had incorrectly‐placed ETT. In all cases, fluoroscopic intubation was described as a useful intervention for ensuring correct ETT placement.

Mathematical rules, confirmed by chest X‐ray:

  1. Tochen's rule suggests that orotracheal tubes should be inserted to a length in cm of 6 plus weight in kg (Tochen 1979); a linear relationship between proper depth of ETT placement and birth weight in 40 preterm infants was reported;

  2. Peterson et al studied the accuracy of the 7‐8‐9 rule for ETT placement (Peterson 2006). Of 75 consecutively intubated infants with a median age of 32 weeks postmenstrual age and mean body weight of 2001 g, the mathematical rule was sufficient to ensure correct tube placement in infants > 750 g body weight. The authors conclude that for infants < 750 g body weight, the 7‐8‐9 rule may lead to an overestimation oft he intubation depth and hence cause serious consequences;

  3. Amarilyo 2009 studied the reliability of a mathematical rule (Tochen's rule) for orotracheal intubation of ELBW infants. Thirty‐one infants < 1000 g who were consecutively intubated at birth according to Tochen's rule (Tochen 1979). Correct ETT placement was tested confirmed through chest X‐ray. Application of Tochen's rule lead to inadequate tube placement in almost half the infants (47%);

  4. Kempley examined the relationship between satisfactory ETT length, gestation and weight in 208 neonatal patients. They were able to determine that ETT length was related to gestation in a linear manner, but the relationship with weight was non‐linear (Kempley 2008). This contradicts Tochen's rule which reported a linear relationship between proper depth of ETT placement and birth weight (Tochen 1979).

Exhaled CO2

CO2 is exhaled from the lungs at concentrations much higher than in air and can be detected with semi‐quantitative colorimetric devices, or measured with devices which give a numeric or graphic value (Roberts 1995; Aziz 1999; Repetto 2001; O'Donnell 2006; Garey 2008). Thus, CO2 detection in expired gas is a very useful method to confirm ETT placement (Kattwinkel 2010). Although they are frequently used to confirm correct ETT placement (Leone 2006; Roehr 2010; Schmölzer 2010b), CO2‐detectors can display false negative results particularly when cardiac output is low (Bhende 1992; Bhende 1995), or when the infant is in severe respiratory failure and the inflation pressure is not high enough to ventilate the lungs (Kamlin 2005; Schmölzer 2011).

We plan to include studies evaluating all commercially available CO2‐detectors (e.g. Pedi‐Cap®, Nellcor Puritan Bennett, Pleasanton, CA; EMMA™ Emergency Capnometer Phasein AB, Danderyd, Sweden, Respironics NICO and NICO2 Philips, Amsterdam, Netherlands; CO2SMO+®, Novametrix Inc., Wallingford, CT, USA). Any studies evaluating similar devices are going to be included in the review. All of these devices are applicable to patients of different size (e.g. neonates, children, adults).

  • Semi‐quantitative colorimetric CO2‐detectors (e.g. Pedi‐Cap®, Nellcor Puritan Bennett, Pleasanton, CA) are disposable noninvasive CO2‐detectors. With each inflation and expiration a pH‐sensitive chemical indicator undergoes colour change, reflecting the change in CO2 concentration in the gas passing through it, even in the presence of low concentrations of CO2. No colour changes indicates the ETT is not in the trachea, or there is low cardiac output, or under ventilated lungs.

  • Systems with either main stream (e.g. EMMA™ Emergency Capnometer Phasein AB, Danderyd, Sweden, Respironics NICO and NICO2 Philips, Amsterdam, Netherlands; CO2SMO+®, Novametrix Inc., Wallingford, CT, USA), side stream (e.g. Puritan Bennett/Datex) or micro stream (e.g. NBP‐75®, Nellcor Puritan Bennett, Plesanton, CA,USA) measurement of end‐tidal CO2. Expired CO2 passes between the beam of infrared light and the photo detector and the absorbance is proportional to the concentration of CO2 in the gas sample. The gas samples can be analysed by the mainstream (in‐line) or sidestream or micro stream (diverting) techniques.

    • Main Stream: With each inflation and expiration an infrared sensor emits infrared light and a photo detector is measuring and displays (either graphical or numerical) the concentration of CO2. Disadvantages might be the heavy weight of the sensor, bulky size or an increased drag on the ETT.

    • Side stream: Side‐stream capnometer are connected to an ETT via a side port and sucking some of the expired gas into their detection sensor. This might result in erroneous CO2 measurements in neonates in particular with small tidal volumes or high respiratory rates.

    • Microstream: Micro stream capnometer are connected to an ETT via a side port. However, they are using lower aspiration flow rates (50ml.min‐1). This might improve suggested erroneous CO2 measurements with the side stream techniques.

The displayed information are the major differences between all available CO2‐detectors. These differences might have an impact on the effectiveness on the feedback to the resuscitator after intubation. Inexperience and lack of knowledge about the displayed waveforms may lead to misinterpretation of the signals. Therefore, anyone using a CO2‐detectors must be trained to interpret the displayed CO2‐waves signals.

Respiratory function monitor

A respiratory function monitor (RFM) measures and displays airway pressure, gas flow and tidal volume. A flow sensor is placed between the ETT and the ventilation device. The inspiratory and expiratory tidal volumes passing through the sensor are automatically calculated by integrating the flow signal (Schmölzer 2010c).

We plan to include studies evaluating all commercially available RFMs (e.g. Florian Neonatal Respiratory Function Monitor, Acutronic Medical Systems AG, Zug, Switzerland; Respironics NICO and NICO2 Philips, Amsterdam, Netherlands; CO2SMO+®, Novametrix Inc., Wallingford, CT, USA). Any studies evaluating similar devices were to be included in the review. All of these devices are applicable to patients of different size (e.g. neonates, children, adults).

  • Florian Neonatal Respiratory Monitor (Acutronic Medical Systems AG, Zug, Switzerland) continuously displays airway pressure, flow and tidal volume waves.

  • Respironics NICO2 Monitor (Philips, Amsterdam, Netherlands) continuously measures and displays numerical values for tidal volume and gas flow.

  • Pneumotachograph CO2SMO+®, (Novametrix Inc., Wellingford, CT, USA) continuously displays flow, airway pressure and tidal volume waves.

The displayed information as well as the design of the screen are the major differences between all available RFMs. These differences might have an impact on the effectiveness on the feedback to the resuscitator after intubation. Lack of experience and knowledge about the displayed waveforms may lead to misinterpretation of the signals. Therefore, anyone using a RFM must be trained to interpret pressure, flow and tidal volume signals (Schmölzer 2010c).

How the intervention might work

Rapid confirmation of correct tube placement at the point of care is important because tube malposition is associated with serious adverse outcomes. These include hypoxaemia, death, pneumothorax or right upper lobe collapse. Confirmation of tube position with chest radiograph is often delayed. This has led to the development of rapid point of care methods to confirm correct tube placement. Current neonatal resuscitation guidelines advise that correct ETT placement should be confirmed by observation of clinical signs and detection of exhaled CO2 (Kattwinkel 2010). Even though these devices are frequently used in the delivery room to assess tube placement (Leone 2006; Roehr 2010; Schmölzer 2011), false negative results can be displayed particularly with decreased cardiac output (Aziz 1999), or if the inflation pressure is too low to ventilate the lungs (Roberts 1995; Repetto 2001; Kamlin 2005; Schmölzer 2011). Recently newer techniques to assess correct tube placement have emerged (e.g. pneumotachograph) which claim to be superior in the assessment of tube placement (Schmölzer 2010a; Schmölzer 2010c; Schmölzer 2011).

Why it is important to do this review

This systematic review will analyse the available literature on various techniques for identification of correct tube placement after oral or nasal intubation in newborn infants managed either in the delivery room or the neonatal intensive care unit, since endotracheal intubation remains a common procedure in both settings, is technically difficult, the success rate of correct ETT placement in particular for junior medical staff is less than 50%, and accidental oesophageal intubation is common (Roberts 1995; Falck 2003; Leone 2005; O'Donnell 2006; Schmölzer 2011). An international consensus statements and guidelines on neonatal resuscitation advise that correct ETT placement should be confirmed by observation of clinical signs and detection of exhaled CO2 (Kattwinkel 2010). However, none of these techniques are without limitation.

Objectives

To compare two‐view chest radiogram (control) versus various techniques (intervention) for identification of correct tube placement after oral or nasal intubation in newborn infants in either the delivery room or neonatal intensive care unit.

  • Two‐view chest radiogram (control) versus clinical assessment (intervention).

  • Two‐view chest radiogram (control) versus exhaled CO2 (intervention).

  • Two‐view chest radiogram (control) versus respiratory function monitoring (intervention).

Subgroup analysis will be performed to determine whether the safety and efficacy vary according to:

  • postmenstrual age: Term (37 weeks’ postmenstrual age and above) versus preterm between 29 and 36 weeks versus preterm < 29 weeks infants;

  • type of clinical assessment (heart rate versus adequate chest wall movements versus confirmation of position by direct laryngoscopy versus observation of ETT passage through the vocal cords versus presence of breath sounds in the axilla and absence of breath sounds in the epigastrium versus condensation in the ETT during ventilation);

  • type of exhaled CO2 monitoring (semi‐quantitative colorimetric versus main stream versus side stream versus micro stream CO2‐detectors);

  • type of respiratory function monitor;

  • skill level of operator (< 1 year; 2 to 5 years; > 5 to 10 years; > 10 years);

  • discipline of operator (Medical, Nursing, Respiratory Therapist).

Methods

Criteria for considering studies for this review

Types of studies

We will include all randomised and quasi‐randomised controlled trials including individual and cluster trials.

Types of participants

We will include all studies where infants are intubated after birth. Therefore, infants could be either intubated in the delivery room, a resuscitation room or a neonatal intensive care unit (infants will be included until discharge).

Types of interventions

  • Two‐view chest radiogram (control) versus clinical assessment (intervention)

  • Two‐view chest radiogram (control) versus exhaled CO2 (intervention)

  • Two‐view chest radiogram (control) versus respiratory function monitoring (intervention)

Types of outcome measures

Primary outcomes

  • Death before discharge

  • Neonatal death < 28 days

Secondary outcomes

  • Success rate of identification of correct ETT placement by two‐view chest radiogram versus clinical assessment

  • Success rate of identification of correct ETT placement by two‐view chest radiogram (control) versus exhaled CO2

  • Success rate of identification of correct ETT placement by two‐view chest radiogram versus respiratory function monitoring

  • The maximum number of intubation attempts with each method of identification of correct ETT placement

  • Death in deliver room

  • Number of endotracheal intubation attempts in delivery room

  • Number of endotracheal intubation attempts in neonatal intensive care unit during hospitalisation

  • Airway injury

  • Accidental malposition of the tube

  • Air leaks (pneumothorax, pneumomediastinum, pneumopericardium, pulmonary interstitial emphysema) reported either individually or as a composite outcome

  • Duration of supplemental oxygen requirement (number of days)

  • Duration of respiratory support, i.e. nasal continuous airway pressure and ventilation via an ETT considered separately and in total (number of days)

  • Chronic lung disease: Need for supplemental oxygen at 28 days of life; need for supplemental oxygen at 36 weeks postmenstrual age for infants born at or before 32 weeks postmenstrual age (Baraldi 2007)

  • Cranial ultrasound abnormalities: Any intraventricular haemorrhage (IVH) grade 3 or 4 according to the classification by Papile 1978 and cystic periventricular leukomalacia

  • Seizures including clinical and electroencephalographic

  • Hypoxic ischaemic encephalopathy (Grade I‐III; Sarnat 1976)

Search methods for identification of studies

We will use the standard methods of the Cochrane Neonatal Review Group guidelines.

Electronic searches

We will search the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) using the following search strategy:

  1. Infant

  2. Newborn

  3. Endotracheal Intubation

  4. ((1 OR 2) AND 3)

  5. Respiratory Function Tests (this includes capnography, flow sensor)

  6. Monitoring, Physiologic

  7. Signs and Symptoms, Respiratory

  8. Respiratory Sounds

  9. Radiography

  10. X‐ray tube placement

  11. (4 AND 5 AND 6 AND 7 AND 8 AND 9)

  12. (11 AND 10)

We will search MEDLINE from1969 to present, CINAHL from 1982 to present, and EMBASE from 1980 to present databases using the above search strategy combined with the following search filters as recommended in theCochrane Handbook for Systematic Reviews of Interventions (Higgins 2011):

  1. randomised controlled trial [pt]

  2. controlled clinical trial [pt]

  3. randomised [tiab]

  4. clinical trials as topic [mesh: noexp]

  5. randomly [tiab]

  6. trial [ti]

  7. 1 or 2 or 3 or 4 or 5 or 6

  8. humans [mh]

  9. 7 and 8

Searching other resources

We will search reference lists of all relevant articles for further studies. We will search the abstracts of the Pediatric Academic Societies (PAS) from 2000 to 2011 and the European Society for Pediatric Research from 2004 to 2011. We will search clinical trials registries for ongoing or recently completed trials [(ClinicalTrials.gov (http://clinicaltrials.gov/); Current Controlled Trials (http://www.controlled‐trials.com/); World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) Search Portal (http://apps.who.int/trialsearch/)]. No language restrictions will be applied and studies published only as abstracts will be considered for inclusion in the review.

Data collection and analysis

We will use the standard methods of the Cochrane Neonatal Review Group.

Selection of studies

We will include all randomised and quasi‐randomised controlled studies including individual and cluster trials.

Data extraction and management

Trial searches, assessments of methodology and extraction of data will be performed independently by each review author with comparison and resolution of any differences found at each stage.

Assessment of risk of bias in included studies

The risk of bias will be assessed according to the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Each included trial will be assessed independently by two review authors using the Cochrane Collaboration's tool for assessing risk of bias, with any disagreement resolved by discussion. Methodology will be assessed regarding blinding of randomisation, intervention and outcome measurements as well as completeness of follow‐up. We will contact authors where any queries arise or where additional data are required.

The risk of bias will be assessed based on the following:

  • random sequence generation;

  • allocation concealment;

  • blinding of participants and personnel

  • blinding of outcome assessment;

  • incomplete outcome data;

  • selective reporting;

  • other bias.

The judgement for each entry will be categorised 'Low risk' of bias, 'High risk' of bias or 'Unclear risk' of bias for either lack of information or uncertainty over the potential for bias.

Measures of treatment effect

We will analyse data using the Cochrane Collaboration's statistical software, Review Manager (Review Manager 2011). Categorical data (e.g. number dying or developing bronchopulmonary dysplasia) will be extracted for each intervention group, and 95% confidence interval (CI), risk ratio (RR), relative risk reduction, risk difference (RD) and number needed to treat (NNT) calculated. Mean and standard deviation will be obtained for continuous data (e.g. number of days of respiratory support, or duration of oxygen dependency) and analysis performed using the mean difference. The fixed‐effect model will be applied. Number needed to treat to benefit (NNTB) will be calculated if the risk difference is statistically significantly reduced and the number needed to treat to harm (NNTH) if the risk difference is statistically significantly increased.

Unit of analysis issues

The unit of analysis is the participating infant in individually randomised trials, and the neonatal unit (or sub‐unit) for cluster randomised trials.

We will include cluster‐randomised trials in the analyses along with individually randomised trials. We will analyse them using the methods described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011) using an estimate of the intra cluster correlation coefficient (ICC) derived from the trial (if possible), or from another source. If ICCs from other sources are used, we will report this and conduct sensitivity analyses to investigate the effect of variation in the ICC. If we identify both cluster‐randomised trials and individually‐randomised trials, we plan to synthesise the relevant information. We will consider it reasonable to combine the results from both if there is little heterogeneity between the study designs and the interaction between the effect of intervention and the choice of randomisation unit is considered to be unlikely. We will acknowledge heterogeneity in the randomisation unit and perform a separate meta‐analysis.

Dealing with missing data

We will contact the authors of included studies to supply missing data. In the case of missing data the number of participants with the missing data will be described in the results section and the 'Characteristics of included studies' table. The results will be only presented for the available participants. We will discuss the implications of the missing data in the discussion of the review.

Assessment of heterogeneity

We will use Review Manager 2011 to assess the heterogeneity of treatment effects between trials. We will use the two formal statistics described below:

  1. The Chi squared test for homogeneity. We will calculate whether statistical heterogeneity is present using the chi‐squared test for homogeneity (P < 0.1). Since this test has low power when the number of studies included in the meta‐analysis is small, we will set the probability at the 10% level of significance (Higgins 2011).

  2. The I2 statistic, to ensure that pooling of data is valid. The impact of statistical heterogeneity will be quantified using I2 statistics available in Review Manager 2011, which describes the percentage of total variation across studies due to heterogeneity rather than sampling error. We will grade the degree of heterogeneity as: 0% to 30%: might be important; 31 to 50%: moderate heterogeneity; 51% to 75%: substantial heterogeneity; 76% to 100%: considerable heterogeneity.

Where there is evidence of apparent or statistical heterogeneity, we will assess the source of the heterogeneity using sensitivity and subgroup analysis looking for evidence of bias or methodological differences between trials.

Assessment of reporting biases

We will try to obtain the study protocols of all included studies and we will compare outcomes reported in the protocol to those reported in the findings for each of the included studies. We will investigate reporting and publication bias by examining the degree of asymmetry of a funnel plot. Where we suspect reporting bias (see selective reporting bias above), we will attempt to contact study authors asking them to provide missing outcome data. Where this is not possible, and the missing data are thought to introduce serious bias, we will explore the impact of including such studies in the overall assessment of results by a sensitivity analysis.

Data synthesis

We will perform statistical analyses according to the recommendations of Cochrane Neonatal Review Group (http://neonatal.cochrane.org/en/index.html). We will analyse all infants randomised on an intention‐to‐treat (ITT) basis. We will analyse treatment effects in the individual trials and will use a fixed‐effect model for meta‐analysis in the first instance to combine the data. Where substantial heterogeneity exists, we will examine the potential cause of heterogeneity in subgroup and sensitivity analysis. When we judge meta‐analysis to be inappropriate, we will analyse and interpret individual trials separately. For estimates of typical RR and RD, we will use the Mantel‐Haenszel method. For measured quantities, we will use the inverse variance method.

Subgroup analysis and investigation of heterogeneity

Subgroup analysis will be performed to determine whether the safety and efficacy vary according to:

  • postmenstrual age: term (37 weeks' postmenstrual age and above) versus preterm between 29 and 36 weeks versus preterm < 29 weeks infants;

  • type of clinical assessment (heart rate versus adequate chest wall movements versus confirmation of position by direct laryngoscopy versus observation of ETT passage through the vocal cords versus presence of breath sounds in the axilla and absence of breath sounds in the epigastrium versus condensation in the ETT during ventilation);

  • type of exhaled CO2 monitoring (semi‐quantitative colorimetric versus main stream versus side stream versus micro stream CO2‐detectors);

  • type of respiratory function monitor;

  • skill level of operator (<1 year; 2‐5 years; >5‐10 years; >10 years);

  • discipline of operator (Medical, Nursing, Respiratory Therapist).

Sensitivity analysis

We will perform sensitivity analyses if issues that are suitable for sensitivity analysis are identified during the review process.