Continuous versus Bolus Gastric Tube Feeding in Very Low Birth Weight Infants Supported with Noninvasive Respiratory Support: A Randomized, Pilot Study.

OBJECTIVES: This study aimed to compare time to full feeding (TFF) between continuous gastric feeding (CGF) and bolus feeding (BF) in very low birth weight (VLBW) infants supported with noninvasive ventilation (NIV) and to evaluate feasibility and identify methodological pitfalls for future large-scale studies. STUDY DESIGN: This study is a randomized controlled, prospective, pilot study. VLBW premature infants, supported with NIV, were randomized while still on trophic feeding <20 mL/kg/day to receive feeding over 2 hours of CGF or over 15- to 30-minute BF. The primary outcome was TFF. Analysis was done by intention to treat. RESULTS: Overall, 32 infants were included in this analysis, 17 in the CGF group and 15 in the BF group. Infants in the CGF group were significantly younger than the BF group (mean ± standard deviation [SD] gestational age [GA] 26.9 ± 1.2 vs. 28.9 ± 1.5 weeks, respectively). TFF was comparable with median (interquartile range [IQR]) for the two groups, 10.0 (10.0, 19.0) days in the BF group versus 12.0 (9.0, 13.0) days in the CGF group (p = 0.59). Feeding length was not found to significantly affect TFF in multivariate analysis correcting for GA. Groups were comparable in weight gain, gastrointestinal complications, length of NIV, bronchopulmonary dysplasia incidence, and age at discharge. Most infants from both groups (60% of BF and 70% of CGF) required changes in feeding length. CONCLUSION: In this pilot study, among VLBW infants supported with NIV, TFF was comparable between the BF and CGF groups. These results should be interpreted with caution due to the small sample size and despite the multivariate analysis correcting for the different GA. Interestingly, most infants required changes in feeding length regardless of their allocation. This feasibility study emphasizes the need for careful attention to randomization and strict feeding protocols including criteria for switching allocation in future large-scale studies aimed at determining the preferred feeding length during NIV in VLBW infants. KEY POINTS: · Among infants supported with NIV, length of feeding affects gastric venting.. · BF might increase gastrointestinal reflux, while continuous feeding hinders gastric decompression.. · Among infants supported by NIV, feeding tolerance was comparable between bolus and continuous groups..

Impact of Continuous Capnography in Ventilated Neonates: A Randomized, Multicenter Study.

OBJECTIVE: To compare the time spent within a predefined safe range of CO2 (30-60 mmHg) during conventional ventilation between infants who were monitored with distal end-tidal CO2 (dETCO2, or capnography) and those who were not. STUDY DESIGN: For this randomized, controlled multicenter study, ventilated infants with a double-lumen endotracheal tube were randomized to 1 of 2 groups: the open (monitored) group, in which data from the capnograph were recorded, displayed to the medical team, and used for patient care, and the masked group, in which data from the capnograph were recorded. However, the measurements were masked and not available for patient care. dETCO2 was compared with PaCO2 measurements recorded for patient care. RESULTS: Fifty-five infants (25 open, 30 masked) participated in the study (median gestational age, 28.6 weeks; range, 23.5-39.0 weeks). The 2 groups were comparable. dETCO2 was in good correlation (r = 0.73; P < .001) and adequate agreement (mean ± SD of the difference, 3.0 ± 8.5 mmHg) with PaCO2. Compared with infants in the masked group, those in the monitored group had significantly (P = .03) less time with an unsafe dETCO2 level (high: 3.8% vs 8.8% or low: 3.8% vs 8.9%). The prevalence of intraventricular hemorrhage or periventricular leukomalacia rate was lower in the monitored group (P = .02) and was significantly (P < .05) associated with the independent factors dETCO2 monitoring and gestational age. CONCLUSION: Continuous dETCO2 monitoring improved control of CO2 levels within a safe range during conventional ventilation in a neonatal intensive care unit. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01572272.

[CAN FOOD THICKENING IMPROVE THE ABILITY OF PREMATURE INFANTS TO ACQUIRE FULL ORAL FEEDING EARLIER? A PILOT STUDY].

BACKGROUND: Acquiring oral feeding skills can take longer in preterm infants and can lengthen their hospital stay. OBJECTIVE: To study whether food thickening could improve preterm infants' ability to reach full oral feeding earlier. METHODS: This is a prospective randomized trial for which 15 infants were recruited upon showing signs of oral feeding readiness. Eight infants fed on human milk were controls. Of the 7 infants fed on formula, five infants were randomized to food thickening with corn flour starch and two infants were given another un-thickened control. RESULTS: Mean gestational age was 29.0 ± 2.3 weeks and mean birth-weight was 1174 ± 325 g. Food thickening had no effect on the time to reach full oral feeding (17.4 ± 6.7 days with thickened formula vs. 18.0 ± 7.0 on un-thickened formula and 12.1 ± 9.5 on human milk) or on the length of stay (66.8 ± 26.0 days vs. 52.5 ± 17.7 and 56.2 ± 25.3, respectivey). Multivariate analysis showed that time to full oral feeding and length of stay were only associated with gestational age or birth-weight and respiratory morbidity, as expressed in the number of ventilation and supplemental oxygen days. Weight gain was faster in those given thickened formula (36.0 ± 7.1 g/day) compared to those on human milk (28.5 ± 6.5 g/day). CONCLUSIONS: Food thickening with corn flour did not shorten the time to reach full oral feeding in preterm infants. This type of food thickening was associated with extra weight gain. Larger blinded prospective studies are needed to confirm our findings.

[OPIATES USE IN VERY-LOW-BIRTH-WEIGHT INFANTS--CALL FOR CAUTION].

BACKGROUND: Very-low-birth-weight (VLBW) infants are occasionally treated with opiates for sedation and pain relief. OBJECTIVE: To study the short term outcomes of VLBW infants treated with opiates. METHODS: We conducted a retrospective study of all VLBW infants born during the period 2006-2010; 45 were treated with opiates (41 fentanyl continuous IV drip and 4 IV morphine prn); 114 served as controls. RESULTS: In the univariate analysis, VLBW infants treated by opiates had significantly lower Gestational Age (GA) (28.3 ± 2.4 vs. 30.3 ± 2.1 weeks) and BW (1012 ± 299 vs. 1204 ± 219 grams] and required longer periods of ventilatory support (30.3 ± 21.0 vs. 7.7 ± 12.0 days) and oxygen supplementation (40.4 ± 40.3 vs. 7.7 ± 17.3 days). They had significantly more intraventricular hemorrhage (IVH), patent ductus arteriosus (PDA), late onset infections, necrotizing enterocolitis (NEC and bronchopulmonary dysplasia (BPD). Time to reach full enteral (32.5 ± 22.1 vs. 15.6 ± 6.1 days) and full oral (64.6 ± 25.0 vs. 42.0 ± 20.7 days) feedings and length of stay (89.6 ± 37.1 vs. 53.7 ± 20.8 days) were significantly longer. In multivariate analysis, after controlling for GA and BW, opiates remained significantly associated only with PDA and longer ventilatory support and time to full enteral feeding. CONCLUSION: The use of opiates in VLBW infants may be associated with short term morbidities. Thus, opiates should be used with caution in this age group, and alternative approaches for sedation or pain relief should be considered. Randomized controlled studies are warranted to support our findings.

Intrapartum Maternal Prophylactic Antimicrobial Treatment and Neonatal Jaundice.

Intrapartum antibiotics are widely used and may potentially affect bilirubin levels and neurotoxicity in the newborn. The aim of this study was to examine the effect of intrapartum antibiotic exposure on neonatal jaundice. We retrospectively collected data from 972 neonates born to 963 mothers. Five hundred forty-five mothers (56.6%) received intrapartum antibiotics. There were no statistically significant differences in maximum bilirubin level (7.82 ± 3.65 vs 7.63 ± 3.71, P = .43) or need for phototherapy (9 [1.62%] vs 4 [0.94%], P = .52) between exposed and non-exposed newborns. The rate of phototherapy was significantly higher only in the group of infants born to mothers who received broad-spectrum antibiotics at 2 to 3.9 hours prior to delivery (χ2 = 10.453, P = .015) and was not higher in the group of exposure >4 hours, which may represent a short transient effect of antibiotics exposure on bilirubin turnover. Further studies are needed to validate this finding.

"Light" on Phototherapy-Complications and Strategies for Shortening Its Duration, A Review of the Literature.

Neonatal hyperbilirubinemia is an extremely common metabolic complication of the neonatal period which may be associated with bilirubin encephalopathy and even death. Adverse neurological consequences are preventable if a timely diagnosis and treatment are provided. Phototherapy is usually the preferred option to decrease hyperbilirubinemia. Although considered to be safe, evidence in recent years has shown that this treatment may not be free of side effects and short- and long-term unfavorable outcomes. These are usually mild or rare, but should be decreased or avoided if possible. Many useful complementary measures and treatments have been described that could shorten the duration of exposure to phototherapy. However, there is no current unequivocal recommendation to use any of the methods presented in this review. Our review aims to depict the wide range of possible complementary treatments to phototherapy, and to provide the scientific and clinical evidence available regarding their usefulness. It is essential that, while utilizing the full potential of phototherapy to treat hyperbilirubinemia, caregivers are aware of its side effects and possible inherent dangers, and seek ways to minimize the exposure to phototherapy to what is really needed for the newborn. Further studies are needed to clarify the preferred complementary treatments that could reduce the duration of exposure to phototherapy without impairing its effectiveness.

Umbilical Cord and Neonatal Transthyretin and Their Relationship to Growth and Nutrition in Preterm Infants.

BACKGROUND: Transthyretin (TTR), also known as prealbumin, has been suggested as an indicator of protein and nutritional status. OBJECTIVE: The aim of this study was to examine the maternal and umbilical cord (UC) TTR in relation to intrauterine growth, and the serum TTR of preterm infants in relation to nutritional status and growth. METHODS: After application of exclusion criteria, 49 preterm infants (mean gestational age and birth-weight 32.9±2.9 weeks and 1822±556 g) were included in the study. Transthyretin was sampled at birth and on days 14, 28, and at discharge with growth parameters and nutritional laboratory test results. RESULTS: Mean UC and maternal TTR were positively correlated (8.5±2.4 mg/dL and 20.4±7.0 mg/dL, r=0.31, P=0.07). Umbilical cord TTR was neither an index of maturity nor of intrauterine growth. Umbilical cord TTR was higher in females (9.4±2.6 versus 7.6±1.8 mg/dL, P=0.015). Maternal TTR was lower in twin pregnancies (16.8±4.9 versus 22.5±7.3 mg/dL, P=0.007). Although TTR levels gradually increased over time in correlation with post-menstrual and chronological ages (r=0.24, P=0.011 and r=0.40, P<0.001, respectively), there was no correlation to weight gain (r=0.10, P=0.41), nutritional status, protein intake, or nutritional laboratory test results. The only significant correlations were between TTR and glucose and triglycerides levels (r=0.51, P<0.001 for both). CONCLUSIONS: Although TTR levels increased over time, we could not demonstrate significant correlations between TTR and indices of the nutritional status in preterm infants at birth or during the neonatal course.

An Observational Study on the Use of Peripheral Intravenous Lines vs. Central Lines in a Neonatal Intensive Care Unit.

BACKGROUND AND OBJECTIVES: There is a debate regarding the preferred intravenous (IV) access for newborns. Our aim was to study practices regarding the choice of vascular access and outcomes. METHODS: A seven-month prospective observational study on IV lines used in all newborns admitted to Bnai Zion Medical Center's neonatal intensive care unit (NICU). RESULTS: Of 120 infants followed, 94 required IV lines. Infants born at ≤32 weeks gestation, or with a head circumference ≤29 cm were more likely to require two or more IV lines or a central line for the administration of parenteral nutrition or medications for longer periods. However, central lines (umbilical or peripherally inserted central catheters (PICC)) were not associated with better nutritional status at discharge based on weight z-scores. Only one complication was noted-a central line-associated bloodstream infection in a PICC. CONCLUSIONS: Our data suggest preferring central IV access for preterm infants born at ≤32 weeks or with a head circumference ≤29 cm. We encourage other NICUs to study their own data and draw their practice guidelines for preferred IV access (central vs. peripheral) upon admission to the NICU.

Cannula With Long and Narrow Tubing vs Short Binasal Prongs for Noninvasive Ventilation in Preterm Infants: Noninferiority Randomized Clinical Trial.

Importance: Use of cannulas with long and narrow tubing (CLNT) has gained increasing popularity for applying noninvasive respiratory support for newborn infants thanks to ease of use, perceived patient comfort, and reduced nasal trauma. However, there is concern that this interface delivers reduced and suboptimal support. Objective: To determine whether CLNT is noninferior to short binasal prongs and masks (SPM) when providing nasal intermittent positive pressure ventilation (NIPPV) in preterm infants. Design, Setting, and Participants: This randomized controlled, unblinded, prospective noninferiority trial was conducted between December 2017 and December 2019 at 2 tertiary neonatal intensive care units. Preterm infants born between 24 weeks' and 33 weeks and 6 days' gestation were eligible if presented with respiratory distress syndrome with the need for noninvasive ventilatory support either as initial treatment after birth or after first extubation. Analysis was performed by intention to treat. Interventions: Randomization to NIPPV with either CLNT or SPM interface. Main Outcomes and Measures: The primary outcome was the need for intubation within 72 hours after NIPPV treatment began. Noninferiority margin was defined as 15% or less absolute difference. Results: Overall, 166 infants were included in this analysis, and infant characteristics and clinical condition (including fraction of inspired oxygen, Pco2, and pH level) were comparable at recruitment in the CLNT group (n = 83) and SPM group (n = 83). The mean (SD) gestational age was 29.3 (2.2) weeks vs 29.2 (2.5) weeks, and the mean (SD) birth weight was 1237 (414) g vs 1254 (448) g in the CLNT and SPM groups, respectively. Intubation within 72 hours occurred in 12 of 83 infants (14%) in the CLNT group and in 15 of 83 infants (18%) in the SPM group (risk difference, -3.6%; 95% CI, -14.8 to 7.6 [within the noninferiority margin], χ2 P = .53). Moderate to severe nasal trauma was significantly less common in the CLNT group compared with the SPM group (4 [5%] vs 14 [17%]; P = .01). There were no differences in other adverse events or in the course during hospitalization. Conclusions and Relevance: In this study, CLNT was noninferior to SPM in providing NIPPV for preterm infants, while causing significantly less nasal trauma. Trial Registration: ClinicalTrials.gov Identifier: NCT03081611.

Inhaled corticosteroids in transient tachypnea of the newborn: A randomized, placebo-controlled study.

OBJECTIVE: Prenatal corticosteroids were shown to reduce the respiratory complication in late preterm infants. Our objective was to determine if early inhaled corticosteroids could alleviate the respiratory distress and morbidity in late preterm and term neonates with transient tachypnea of the newborn (TTN). STUDY DESIGN: Double-blind, randomized placebo-controlled, multicenter pilot study. Infants born at >34 weeks gestational age with TTN at 4 h of age were randomized to two doses, 12 h apart, of inhaled Budesonide 1000 µg/dose or placebo within 6 h from delivery. Analysis was done by intention to treat. RESULTS: The study (n = 24) and control (n = 25) groups were comparable in birth characteristics (gestational age: 36.8 ± 1.9 vs 36.4 ± 1.8 weeks) and clinical condition at the time of recruitment (vital signs, clinical score, ventilation support, and blood gases). There was no difference between the study and control groups in clinical score (based on grunting, retractions, ala nasi, and respiratory rate) at recruitment and at 12, 24, and 48 h after the first inhalation (4.3 ± 1.6 vs 4.1 ± 2.1; 1.9 ± 1.8 vs 1.5 ± 1.7; 1.1 ± 1.4 vs 1.3 ± 1.6; 0.5 ± 0.8 vs 0.6 ± 1.0; respectively). Respiratory support at each time point, time to spontaneous unsupported breathing (67.4 ± 74.1 vs 75.2 ± 95.2 h), time to full feeds (86.7 ± 68.7 vs 84.3 ± 66.6 h) and length of stay (9.9 ± 5.5 vs 12.4 ± 8.0 days) did not differ between the groups. We did not detect any side effects. CONCLUSIONS: Our pilot study was unable to detect a beneficial effect of early administration of inhaled steroids on the clinical course of TTN in late preterm and term infants.

Diagnostic accuracy of capnography during high-frequency ventilation in neonatal intensive care units.

BACKGROUND AND OBJECTIVE: High-frequency ventilation (HFV) is a powerful tool for CO2 elimination, and thus requires careful monitoring of CO2 . Our aim was to assess the diagnostic accuracy (correlation, agreement, and trending) of continuous distal capnography (dCap) with PaCO2 in infants ventilated with HFV. DESIGN: This was a prospective, observational, multicenter study. dCap was compared with simultaneous PaCO2 ("gold standard") drawn from indwelling arterial line for patient care in term and preterm infants ventilated with HFV. dCap was obtained via the side-port of a double-lumen endotracheal-tube by a Microstream capnograph with specially designed software for HFV. RESULTS: Twenty-four infants participated in the study (median [range] gestational age [GA]: 26.8 [23.6-38.6] weeks). Analysis included 332 measurements. dCap was in correlation (r = 0.70, P < 0.001) but with less than adequate agreement (mean difference ± SD of the differences: -11.7 ± 10.3 mmHg) with PaCO2 . Comparable findings were found in the subgroup of infants <1,000 g (n = 240 measurements). Correlations were maintained in severe lung disease. Changes in dCap and in PaCO2 for consecutive measurements within each patient were correlated (r = 0.63, P < 0.001). Area under the receiver operating curves (ROC) for dCap to detect high (>60 mmHg) or low (<30 mmHg) PaCO2 was 0.83 (CI: 0.76-0.90) and 0.88 (CI: 0.79-0.97), respectively; P < 0.001. CONCLUSIONS: Our prospective study suggests that continuous dCap in infants ventilated with HFV may be helpful for trends and alarm for unsafe levels of PaCO2 . dCap is only a complimentary tool and cannot replace PaCO2 sampling because the agreement between these measurements was less than adequate.

A randomized pilot study comparing heated humidified high-flow nasal cannulae with NIPPV for RDS.

OBJECTIVE: To compare the requirement for endotracheal ventilation in preterm infants treated with heated, humidified high-flow nasal cannula (HHHFNC) with those treated with nasal intermittent positive pressure ventilation (NIPPV) for the primary treatment of respiratory distress syndrome (RDS). STUDY DESIGN: Randomized, controlled, prospective, single-center pilot study. Infants (gestational age [GA] <35 weeks, birth weight [BW] >1,000 g) with RDS were randomly assigned to receive HHHFNC (38 infants) delivered by Vapotherm® device (Precision Flow™ or 2000 i, Vapotherm Inc., Stevensville, MD), at flows between 1.0 and 5.0 L/min, or NIPPV (38 infants) delivered by the SLE 2000 or 5000. Surfactant was administered as rescue therapy. Analysis was done by intention-to-treat. RESULTS: Infant's characteristics ([mean ± SD] GA 31.8 ± 2.3 vs. 32.0 ± 2.3 weeks) and cardio-respiratory status at study entry (FiO2 0.25 ± 0.05 vs. 0.26 ± 0.07; SpO2 90 ± 6% vs. 87 ± 12; PCO2 54.4 ± 10.4 vs. 52.6 ± 8.0 mmHg) were comparable for the HHHFNC and NIPPV groups. There was no significant difference in the need for endotracheal ventilation (28.9% vs. 34.2%) between HHHFNC and NIPPV groups. One infant failed HHHFNC and succeeded on NIPPV. The rate of neonatal morbidities (pneumothorax, bronchopulmonary dysplasia, intra-ventricular hemorrhage, necrotizing enterocolitis, patent ductus arteriosus, and nasal trauma) was comparable in both groups. Duration of nasal support was longer with HHHFNC compared with NIPPV (5.4 ± 4.0 vs. 2.6 ± 1.9 days, P = 0.006) but the duration of endotracheal ventilation, time to full feeds, and length of stay were comparable. CONCLUSIONS: Our pilot study suggests that HHHFNC maybe as effective as NIPPV in preventing endotracheal ventilation in the primary treatment of RDS in premature infants (<35 weeks GA and BW >1,000 g).

The Impact of Rudeness on Medical Team Performance: A Randomized Trial.

BACKGROUND AND OBJECTIVES: Iatrogenesis often results from performance deficiencies among medical team members. Team-targeted rudeness may underlie such performance deficiencies, with individuals exposed to rude behavior being less helpful and cooperative. Our objective was to explore the impact of rudeness on the performance of medical teams. METHODS: Twenty-four NICU teams participated in a training simulation involving a preterm infant whose condition acutely deteriorated due to necrotizing enterocolitis. Participants were informed that a foreign expert on team reflexivity in medicine would observe them. Teams were randomly assigned to either exposure to rudeness (in which the expert's comments included mildly rude statements completely unrelated to the teams' performance) or control (neutral comments). The videotaped simulation sessions were evaluated by 3 independent judges (blinded to team exposure) who used structured questionnaires to assess team performance, information-sharing, and help-seeking. RESULTS: The composite diagnostic and procedural performance scores were lower for members of teams exposed to rudeness than to members of the control teams (2.6 vs 3.2 [P = .005] and 2.8 vs 3.3 [P = .008], respectively). Rudeness alone explained nearly 12% of the variance in diagnostic and procedural performance. A model specifying information-sharing and help-seeking as mediators linking rudeness to team performance explained an even greater portion of the variance in diagnostic and procedural performance (R(2) = 52.3 and 42.7, respectively). CONCLUSIONS: Rudeness had adverse consequences on the diagnostic and procedural performance of the NICU team members. Information-sharing mediated the adverse effect of rudeness on diagnostic performance, and help-seeking mediated the effect of rudeness on procedural performance.

Continuous integrated distal capnography in infants ventilated with high frequency ventilation.

OBJECTIVE: To assess within a feasibility study the correlation, agreement, and trending of continuous integrated distal capnography (dCap) with PaCO(2) in infants on HFV. STUDY DESIGN: Sixteen premature infants [median (range) gestational age: 26.5 (24.7-34.7) weeks], ventilated with HFV (mean ± SD airway pressure: 8.1 ± 2.1 cmH(2) O, FiO(2) : 0.39 ± 0.21) for RDS, intubated with a double-lumen endotracheal-tube and whose data were recorded on a bedside computer participated in the study. Side-stream dCap was measured via the extra-port of a double-lumen endotracheal-tube by a Microstream capnograph, with a specially designed software for HFV and compared with simultaneous PaCO(2) . Integrated time-window analysis of the data was performed retrospectively on data collected prospectively. RESULTS: Analysis included 195 measurements. The correlation of dCap with PaCO(2) (r = 0.68, P < 0.0001) and the agreement (bias ± precision: -2.0 ± 10.7 mmHg) were adequate. Area under the ROC curves for dCap to detect high (>60 mmHg) or low (<35 mmHg) PaCO(2) was 0.79 (CI: 0.70-0.89) and 0.87 (CI: 0.73-1.00), respectively; P < 0.0001. Changes in dCap and in PaCO(2) for consecutive measurements within each patient were adequately correlated (r = 0.65, P < 0.0001). CONCLUSIONS: Continuous integrated dCap is feasible in premature infants ventilated with HFV and can be helpful for trends and alarm for unsafe levels of PaCO(2) .

A novel method of distal end-tidal CO2 capnography in intubated infants: comparison with arterial CO2 and with proximal mainstream end-tidal CO2.

OBJECTIVE: The objective of this study was to evaluate a novel method of distal end-tidal CO2 capnography by comparison with PaCO2 and with the more standard method that measures mainstream proximal end-tidal CO2 in intubated infants. METHODS: Included in the study were all infants who were ventilated with conventional mechanical ventilation and intubated with a double-lumen endotracheal tube in our NICU during the study period. Data were collected prospectively from 2 capnographs simultaneously and compared with PaCO2. Sidestream distal end-tidal CO2 was measured by a Microstream capnograph via the extra port of a double-lumen endotracheal tube. Mainstream proximal end-tidal CO2 was measured via capnograph connected to the endotracheal tube. RESULTS: Twenty-seven infants (median [range] birth-weight: 1835 [490-4790] g; gestational age: 32.5 [24.8-40.8] weeks) participated in the study. We used for analysis 222 and 212 measurements of distal end-tidal CO2 and proximal end-tidal CO2, respectively. Distal compared with proximal end-tidal CO2 had a better correlation with PaCO2 and a better agreement with PaCO2. The accuracy of distal end-tidal CO2 decreased, but it remained a useful measure of PaCO2 in the high range of PaCO2 (>or=60 mmHg) or in conditions of severe lung disease. A subanalysis for infants who weighed<1500 g (13 infants, 84 observations) revealed a good correlation and agreement between distal end-tidal CO2 and PaCO2 and poor correlation and agreement for proximal end-tidal CO2. CONCLUSIONS: Distal end-tidal CO2 measured via a double-lumen endotracheal tube was found to have good correlation and agreement with PaCO2, remained reliable in conditions of severe lung disease, and was more accurate than the standard mainstream proximal end-tidal CO2.