Endoscopic intratracheal carbon dioxide measurements during pediatric flexible bronchoscopy

Alveolar ventilation in children during flexible bronchoscopy

BACKGROUND

Hypoxia and hypercarbia complicate flexible bronchoscopy (FB). Unlike oxygenation by pulse-oximetry, alveolar ventilation is not routinely monitored during FB. The aim of this study was to investigate ventilation in children undergoing FB by measuring carbon-dioxide (CO₂ ) levels using the transcutaneous technique.

METHODS

Children admitted for FB were recruited. In addition to routine monitoring, transcutaneous CO₂ (TcCO₂ ) levels were recorded. All were sedated using the same protocol.

RESULTS

Ninety-five children were studied. There was no association between peak TcCO₂ or rise in TcCO₂ and age, weight percentile, bronchoscope size, or diagnosis. Median baseline TcCO₂ was 36 mmHg (IQR 32,40), median peak TcCO₂ was 51 mmHg (IQR 43,62) with median TcCO₂ rise of 17 mmHg (IQR 6.5,23.7). A rise of 15 mmHg or higher was recorded in 55% (n = 52) patients. Children requiring total propofol dose over 3.5 mg/kg had a significantly higher TcCO₂ peak of 57.6 mmHg (IQR 47.8,66.7) compared to 47.1 mmHg (IQR 40,57) (P = 0.004) and a higher rise in TcCO₂ 22.5 mmHg (IQR 17,33.9) compared to 13.6 mmHg (6,22) (P = 0.001). Results were not affected by intranasal midazolam and broncho-alveolar lavage. No complications were reported. Non clinically significant (i.e., not lower than 90%) brief drops in oxygen saturation were observed.

CONCLUSIONS

A large proportion of children undergoing FB have significant alveolar hypoventilation indicated by a rise in TcCO₂ . Monitoring ventilation with TcCO₂ is feasible and should be added during FB particularly in cases that are expected to require large amounts of sedation and patients susceptible to complications from respiratory acidosis. Pediatr Pulmonol. 2016;51:1177-1182. © 2016 Wiley Periodicals, Inc.

Interventions for primary (intrinsic) tracheomalacia in children

BACKGROUND

Tracheomalacia, a disorder of the large airways where the trachea is deformed or malformed during respiration, is commonly seen in tertiary paediatric practice. It is associated with a wide spectrum of respiratory symptoms from life-threatening recurrent apnoea to common respiratory symptoms such as chronic cough and wheeze. Current practice following diagnosis of tracheomalacia includes medical approaches aimed at reducing associated symptoms of tracheomalacia, ventilation modalities of continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP), and surgical approaches aimed at improving the calibre of the airway (airway stenting, aortopexy, tracheopexy).

OBJECTIVES

To evaluate the efficacy of medical and surgical therapies for children with intrinsic (primary) tracheomalacia.

SEARCH METHODS

The Cochrane Airways Group searched the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Airways Group's Specialised Register, MEDLINE and EMBASE databases. The Cochrane Airways Group performed the latest searches in March 2012.

SELECTION CRITERIA

All randomised controlled trials (RCTs) of therapies related to symptoms associated with primary or intrinsic tracheomalacia.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data from the included study independently and resolved disagreements by consensus.

MAIN RESULTS

We included one RCT that compared nebulised recombinant human deoxyribonuclease (rhDNase) with placebo in 40 children with airway malacia and a respiratory tract infection. We assessed it to be a RCT with overall low risk of bias. Data analysed in this review showed that there was no significant difference between groups for the primary outcome of proportion cough-free at two weeks (odds ratio (OR) 1.38; 95% confidence interval (CI) 0.37 to 5.14). However, the mean change in night time cough diary scores significantly favoured the placebo group (mean difference (MD) 1.00; 95% CI 0.17 to 1.83, P = 0.02). The mean change in daytime cough diary scores from baseline was also better in the placebo group compared to those on nebulised rhDNase, but the difference between groups was not statistically significant (MD 0.70; 95% CI -0.19 to 1.59). Other outcomes (dyspnoea, and difficulty in expectorating sputum scores, and lung function tests at two weeks also favoured placebo over nebulised rhDNase but did not reach levels of significance.

AUTHORS' CONCLUSIONS

There is currently an absence of evidence to support any of the therapies currently utilised for management of intrinsic tracheomalacia. It remains inconclusive whether the use of nebulised rhDNase in children with airway malacia and a respiratory tract infection worsens recovery. It is unlikely that any RCT on surgically based management will ever be available for children with severe life-threatening illness associated with tracheomalacia. For those with less severe disease, RCTs on interventions such as antibiotics and chest physiotherapy are clearly needed. Outcomes of these RCTs should include measurements of the trachea and physiological outcomes in addition to clinical outcomes.

Prospective assessment of protracted bacterial bronchitis: airway inflammation and innate immune activation

Protracted bacterial bronchitis (PBB) is a common cause of paediatric chronic moist cough. PBB is defined as the presence of isolated chronic moist cough which resolves with antibiotic therapy within 2 weeks and an absence of pointers suggesting alternative diagnoses. Our aim was to describe the clinical profile and examine the airway cellularity and likely promoters of neutrophilic inflammation in the bronchoalveolar lavage (BAL) of children with PBB compared with chronic cough due to other causes and controls. We explored the innate immune signaling receptors, toll-like receptors (TLR)-2 and TLR-4, as well as relevant effector molecules. A cross-sectional comparison was made of 100 children median age 2.58 years (with either PBB, coughing due to another cause or no cough controls) who underwent flexible bronchoscopy with lavage. BAL was evaluated for airway cytology, microbiology, inflammatory mediators interleukin 8 (IL-8) and active matrix metalloproteinase 9 (MMP-9) and TLR-2 and TLR-4 messenger RNA (mRNA) expression. Children with PBB had marked airway neutrophilia and increased median cytokine levels when compared to those with cough that resolved naturally and no cough controls: IL-8 0.67 versus 0.07 and 0.06 ng/ml (P < 0.005) and active MMP-9 7.25 versus 1.35 and 0.38 ng/ml (P < 0.005). The values for TLR-2 and TLR-4 mRNA expression were significantly elevated in children with PBB when compared to the control group. PBB is a paediatric condition which presents with chronic moist cough and its airway profile is characterized by intense neutrophilic airway inflammation with marked inflammatory mediator response and evidence of innate immune activation.

[Monitoring airway gas in pediatric anesthesia: an experimental model for endotracheal gas measurement]

BACKGROUND

We designed an endotracheal probe for measuring inspired and expired gas fractions during pediatric general anesthesia.

OBJECTIVE

To compare the gas fractions measured by means of intratracheal and extratracheal monitoring.

MATERIAL AND METHODS

The study included ASA 1 patients between the ages of 7 and 12 years under inhaled anesthesia with mechanical ventilation. The following parameters were recorded inside and outside the trachea: inspired and expired oxygen, nitric oxide (N2O) and sevoflurane fractions; the expired and inspired fraction gradients; PaCO2; and end-tidal carbon dioxide (ETCO2). Measurements were taken by an airflow sensor (Pedi-Lite) in the circuit before the point of connection to the endotracheal tube and by an intratracheal probe placed between the tube and the carina. Both sensors were connected to the same monitor. Measurements were taken on intubation and 5, 10, 15, 20, 30, 40, 50, and 60 minutes thereafter. PaCO2 was recorded at the same time. The recorded values were analyzed using the t test and the Pearson product moment correlation coefficient (r), and regression models were constructed using analysis of variance.

RESULTS

Seventy-one patients were enrolled in the study. The mean difference (SD) ETCO2 was 5 (3) mm Hg higher according to endotracheal measurement (P < .005), and that measurement was almost identical (+/-13 mm Hg) to the PaCO2 (P < or = .5). The inspired/expired gradients of endotracheal measurement of oxygen and N2O were 3 (2) points higher (P < .05) than the gradients of extratracheal measurements. In the case of sevoflurane gradients, however, the extratracheal values were higher (mean difference, 0.6 [0.2] points, P < .05). The inspired/expired oxygen and N2O gradients became equal after 18 (3) minutes; the sevoflurane gradients became equal after 8 (2) minutes.

CONCLUSIONS

Intratracheal and extratracheal measurements of the inspired and expired fractions of mixed gases provide different results.

Longitudinal quantification of growth and changes in primary tracheobronchomalacia sites in children

RATIONALE

Longitudinal follow-up of children with tracheobronchomalacia is essential to improving our understanding of these disorders, yet currently, there is no such data.

OBJECTIVES

To longitudinally define malacia sites and quantify the cross-sectional area (CSA) of the lumen using a bronchoscopic technique and to relate these measurements to illness profiles.

METHODS

The validated color histogram mode technique was utilized to quantify primary malacia lesions and airway sites' CSA. Illness frequency, validated scales of illness and cough diary scores were prospectively used to assess clinical profiles.

RESULTS

Thirty-five malacia sites were defined from the 2 studies of 21 children. CSA of 21 (60%) of the malacia lesions increased, 5 (14%) new lesions appeared, 5 (14%) decreased in size, 3 (8%) remained unchanged, and 1(3%) was indeterminate. Overall there was no statistically significant change in paired-data assessments of malacia sites' area while there was a significant increase in area of non-malacia sites. The median yearly growth rate for the malacia sites and non-malacia was 3.65 mm2/year sites and 5.38 mm2/year, respectively (P = 0.31). The type and severity of lesion was not associated with any difference in growth rates, illness frequency or clinical scores.

CONCLUSIONS

Malacia lesions increase in size at the same rate as non-malacia sites. However malacia may worsen and new primary lesions may develop. Neither malacia type nor severity influences their growth pattern or illness profile.

A bronchoscopic scoring system for airway secretions--airway cellularity and microbiological validation

There is currently no validated scoring system for quantification of airway secretions in children. A user friendly, valid scoring system of airway secretions during flexible bronchoscopy (FB) would be useful for comparative purposes in clinical medicine and research. The objective of this study was to validate our bronchoscopic secretion (BS) scoring system by examining the relationship between the amount of secretions seen at bronchoscopy with airway cellularity and microbiology. In 106 children undergoing FB, the relationship of BS grades with bronchocalveolar lavage (BAL) cellularity and infective state (bacterial and viral infections) were examined using receptor operator curves (ROC). BAL was obtained according to European Respiratory Society guidelines; first lavage for microbiology and second lavage for cellularity. Area under the ROC was significant for total cell count (TCC) and neutrophil % but not for lymphocyte %. BS grade significantly related to infection positive state (chi(trend) (2) = 5.85, P = 0.016). The area under the ROC for infection positive state versus BS grade was 0.645, 95% CI 0.527-0.763. The BS scoring system is a valid method for quantifying airway secretions in children undergoing bronchoscopy. The system related well to airway cellularity and neutrophilia, as well as to an airway infective state. However, the system is only complementary to cell counts and cultures and cannot replace these laboratory quantification techniques.

Evaluation and outcome of young children with chronic cough

OBJECTIVE

To evaluate the use of an adult-based algorithmic approach to chronic cough in a cohort of children with a history of > 3 weeks of cough and to describe the etiology of chronic cough in this cohort.

METHODS

A prospective cohort study of children referred to a tertiary hospital with a history of > 3 weeks of cough between June 2002 and June 2004. All included children followed a pathway of investigation (including flexible bronchoscopy and evaluation of airway cytology via BAL) until diagnosis was made and/or their cough resolved.

RESULTS

In our cohort of 108 young children (median age 2.6 years), the majority had wet cough (n = 96; 89%), and BAL fluid samples obtained during bronchoscopy led to a diagnosis in 45.4% (n = 49). The most common final diagnosis was protracted bacterial bronchitis (n = 43; 39.8%). These patients had neutrophil levels on BAL samples that were significantly higher than those in other diagnostic groups (p < 0.0001). Asthma, gastroesophageal reflux disease (GERD), and upper airway cough syndrome (UACS), which are common causes of chronic cough in adults, were found in < 10% of the cohort (n = 10).

CONCLUSIONS

The adult-based anatomic pathway, which involves the investigation and treatment of patients with asthma, GERD, and UACS first is largely unsuitable for use in the management of chronic cough in young children as the common etiologies of chronic cough in children are different from those in adults.

Airway sizes and proportions in children quantified by a video-bronchoscopic technique

Background

A quantitative understanding of airway sizes and proportions and a reference point for comparisons are important to a pediatric bronchoscopist. The aims of this study were to measure large airway areas, and define proportions and factors that influence airway size in children.

Methods

A validated videobronchoscope technique was used to measure in-vivo airway cross-sectional areas (cricoid, right (RMS) and left (LMS) main stem and major lobar bronchi) of 125 children. Airway proportions were calculated as ratios of airways to cricoid areas and to endotracheal tube (ETT) areas. Mann Whitney U, T-tests, and one-way ANOVA were used for comparisons and standard univariate and backwards, stepwise multivariate regression analyses were used to define factors that influence airway size.

Results

Airways size increased progressively with increasing age but proportions remained constant. The LMS was 21% smaller than the RMS. Gender differences in airways' size were not significant in any age group or airway site. Cricoid area related best to body length (BL): cricoid area (mm²) = 26.782 + 0.254* BL (cm) while the RMS and LMS area related best to weight: RMS area (mm²) = 23.938 + 0.394*Wt (kg) and LMS area (mm²) = 20.055 + 0.263*Wt (kg) respectively. Airways to cricoid ratios were larger than airway to ETT ratios (p = 0.0001).

Conclusion

The large airways progressively increase in cross sectional area size, maintain constant proportional relationships to the cricoid and are gender independent across childhood. Anthropometric factors (body length and weight) are significantly related to but only have weakly predictive influences on major airway size. The cricoid is the most suitable comparator for other airway site measurements. These data provide for quantitative comparisons of airway lesions.

Interventions for primary (intrinsic) tracheomalacia in children

BACKGROUND

Tracheomalacia, a disorder of the large airways where the trachea is deformed or malformed during respiration is commonly seen in tertiary paediatric practice. It is associated with a wide spectrum of respiratory symptoms from life threatening recurrent apnea to common respiratory symptoms such as chronic cough and wheeze. Current practice following diagnosis of tracheomalacia include medical approaches aimed at reducing associated symptoms of tracheomalacia, ventilation modalities of continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP) and, surgical approaches aimed at improving the caliber of the airway (airway stenting, aortopexy, tracheopexy).

OBJECTIVES

To evaluate the efficacy of medical and surgical therapies for children with intrinsic (primary) tracheomalacia.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Airways Group Specialised Register, MEDLINE and EMBASE databases were searched by the Cochrane Airways Group. The latest searches were performed in Feb 2005.

SELECTION CRITERIA

All randomised controlled trials of therapies related to symptoms associated with primary or intrinsic tracheomalacia.

DATA COLLECTION AND ANALYSIS

Results of searches were reviewed against pre-determined criteria for inclusion. No eligible trials were identified and thus no data were available for analysis.

MAIN RESULTS

No randomised controlled trials (RCTs) that examined therapies for intrinsic tracheomalacia were found. Eight of the more recent (last 11 years) non randomised controlled trials reported a benefit from the various surgical interventions. The success was however not universal and in some studies severe adverse events occurred.

AUTHORS' CONCLUSIONS

There is currently an absence of evidence to support any of the therapies currently utilised for management of intrinsic tracheomalacia. It is unlikely that any RCT on surgically based management will ever be available for children with severe life threatening illness associated with tracheomalacia. For those with less severe disease, RCTs are clearly needed. Outcomes of these RCTs should include measurements of the trachea and physiological outcomes in addition to clinical outcomes.

A new method for objective identification and measurement of airway lumen in paediatric flexible videobronchoscopy

BACKGROUND

Accurate measurements of airway and lesion dimensions are important to the developmental progress of paediatric bronchoscopy. The malacia disorders are an important cause of respiratory morbidity in children, but no methods are currently available to measure these lesions or the airway lumen accurately. A new measurement technique is described here.

METHODS

The magnification power of a paediatric videobronchoscope was defined and a simple and user friendly computer based program (Image J) was used to develop an objective technique (colour histogram mode technique, CHMT) for measurement of the airway lumen.

RESULTS

In vivo intra-observer and inter-observer repeatability coefficients for repeated area measurements from 28 images using the Bland-Altman method were 0.9 mm2 and 1.6 mm2, respectively. The average intraclass correlation coefficient for repeated measurements of area was 0.93. In vitro validation measurements using a 2 mm diameter tube resolved radii measurements to within 0.1 mm (coefficient of variability 8%). An "acceptable result" was defined in 92% of 734 images completed with the CHMT alone and 8% with its modification. The success rate for two of three images being within 10% of each other's area was 100%. Measurements of cricoid cross sectional areas from 116 patients compared with expected airway areas for age derived from endotracheal tube sizes were comparable.

CONCLUSIONS

The CHMT method of identifying and measuring airway dimensions is objective, accurate, and versatile and, as such, is important to the future development of flexible videobronchoscopy.

Cough quality in children: a comparison of subjective vs. bronchoscopic findings

Background

Cough is the most common symptom presenting to doctors. The quality of cough (productive or wet vs dry) is used clinically as well as in epidemiology and clinical research. There is however no data on the validity of cough quality descriptors. The study aims were to compare (1) cough quality (wet/dry and brassy/non-brassy) to bronchoscopic findings of secretions and tracheomalacia respectively and, (2) parent's vs clinician's evaluation of the cough quality (wet/dry).

Methods

Cough quality of children (without a known underlying respiratory disease) undergoing elective bronchoscopy was independently evaluated by clinicians and parents. A 'blinded' clinician scored the secretions seen at bronchoscopy on pre-determined criteria and graded (1 to 6). Kappa (K) statistics was used for agreement, and inter-rater and intra-rater agreement examined on digitally recorded cough. A receiver operating characteristic (ROC) curve was used to determine if cough quality related to amount of airway secretions present at bronchoscopy.

Results

Median age of the 106 children (62 boys, 44 girls) enrolled was 2.6 years (IQR 5.7). Parent's assessment of cough quality (wet/dry) agreed with clinicians' (K = 0.75, 95%CI 0.58–0.93). When compared to bronchoscopy (bronchoscopic secretion grade 4), clinicians' cough assessment had the highest sensitivity (0.75) and specificity (0.79) and were marginally better than parent(s). The area under the ROC curve was 0.85 (95%CI 0.77–0.92). Intra-observer (K = 1.0) and inter-clinician agreement for wet/dry cough (K = 0.88, 95%CI 0.82–0.94) was very good. Weighted K for inter-rater agreement for bronchoscopic secretion grades was 0.95 (95%CI 0.87–1). Sensitivity and specificity for brassy cough (for tracheomalacia) were 0.57 and 0.81 respectively. K for both intra and inter-observer clinician agreement for brassy cough was 0.79 (95%CI 0.73–0.86).

Conclusions

Dry and wet cough in children, as determined by clinicians and parents has good clinical validity. Clinicians should however be cognisant that children with dry cough may have minimal to mild airway secretions. Brassy cough determined by respiratory physicians is highly specific for tracheomalacia.