Capillary Blood Gas Research Articles

Agreement between arterial and non-arterialised fingertip capillary blood gas and acid-base values

ABSTRACTBackground: Arterial puncture is considered the gold standard for obtaining blood gas and acid-base values and facilitates the assessment of acutely and critically ill patients, as well as control of patients in long-term oxygen therapy (LTOT). Substitutional capillary sampling has been proposed, as researchers cite lower complication rates, physician independence, lower degree of invasiveness and higher degree of patient comfort. An arterialised earlobe is considered the method of choice to obtain capillary blood sampling, but in an acute setting, the need for vasodilating pastes may be time-consuming and impractical.The aim of this study is to examine whether accurate blood gas and acid-base measurements can be obtained using non-arterialised fingertip blood.Materials and methods: Consecutive arterial punctures and non-arterialised capillary blood samples were drawn from 62 patients with stable-phase chronic obstructive pulmonary disease (COPD), and subsequently analysed. Agreement between arterial and capillary blood gas values was compared using the method recommended by Bland and Altman.Results: Results show that limits of agreement (LoA) regarding PO2 (LoA: −1.27–4.45 kPa); Base Excess (LoA: −1.35–0.55); lactate (LoA: −0.77–0.20 mmol/l) and SO2 (LoA: −0.02–0.06) are wider than what would be applicable for clinical use. However, clinically acceptable LoA were obtained regarding PCO2 (LoA: −0.64–0.38 kPa); pH (LoA: −0.02–0.03), and HCO3− (LoA: −1.06–0.55 mmol/l).Conclusion: LoA for PCO2, pH and HCO3− indicate that measurement of these parameters in non-arterialised capillary blood may be useful in clinical practice/an acute setting.What this paper adds:Capillary blood sampling provides a fast, non-invasive means of obtaining blood gas-values;Traditionally, capillary blood sampling for blood gas analysis is obtained from the earlobe using arterialisation;The present study presents accurate measurements of PCO2, HCO3− and pH using non-arterialised fingertip capillary blood;The present study is the first to show this in a population of stable-phase COPD patients.

Reducing incidence of red cell transfusion among preterm babies in a tertiary care neonatal intensive care unit: A retrospective observational study

Background: Preterm neonates in the neonatal intensive care unit (NICU) receive a greater number of red cell transfusions (RCTs) than any other hospitalized group. Iatrogenic anemia, secondary to blood draws, increases the need for transfusions in preterm neonates. Blood transfusions are related to transfusion reactions and risk of transmitting infection. Objective: This retrospective study was done to find the incidence of RCT in neonates born less than or at 32+0 weeks of gestation and to establish whether requirement of blood transfusions could be further decreased. Methodology: A retrospective study of all intramural births less than or at 32+0 weeks of gestation who were admitted and discharged from the NICU of Fortis La Femme, GK-II, New Delhi, from February 1, 2017, to January 31, 2018, was done, and the data were analyzed by statistical software IBM SPSS Statistics for Windows, Version 21.0. Results: Forty-three babies were studied, of which 16 were female. The mean gestation age was 29.49 ± 2.35 weeks, and the mean birth weight was 1234.93 ± 368.737 grams. Seventeen (39.5%) neonates required RCT during their hospital stay, of which 11 (64.7%), 2 (11.7%), 3 (17.6%), and 1 (5.8%) neonate received 1, 2, 3, and 6 unit of RCT, respectively. The incidence of RCT was significantly higher in babies with sepsis and babies who received surfactant. RCTs were observed to be significantly higher in babies who were managed with invasive methods such as mechanical ventilation and use of peripherally inserted central catheter/central lines for administration of total parenteral nutrition. The number of RCTs required also correlated with the number of ventilated days and days on continuous positive airway pressure. Conclusion: Majority of the neonates born less than or at 32+0 weeks can be managed without the requirement of RCT. A restrictive blood transfusion policy, judicious use of blood investigation, use of microsampling and point of care investigations such as capillary blood gas, early initiation of enteral feeds and iron supplementation, prevention of sepsis, judicious use of venous/arterial lines and noninvasive management protocols has helped reduce blood transfusion in preterm neonates.

An Infant with Severe Stridor and Cyanosis at Birth

A male infant born via vaginal delivery presents with biphasic stridor, cyanosis, tachypnea, chest retractions, and copious secretions since birth. ### Prenatal and Birth Histories ### Presentation After birth, the infant was noted to have increased work of breathing, severe biphasic stridor, and cyanosis. He was briefly given positive pressure ventilation for apnea, and was then administered CPAP with a fraction of inspired oxygen (Fio2) of 100%. Multiple attempts at intubation were unsuccessful; a laryngeal mask airway placement was not attempted. The infant was subsequently given high-flow nasal cannula at 3 L/min with an Fio2 of 1 and transported to the NICU at a tertiary hospital. The infant continued to have stridor with significant increased work of breathing, but saturations remained 85% or greater on 3 L/min and an Fio2 of 1. Before transport, a capillary blood gas showed a pH of 7.08 and Pco2 of 89 mm Hg (12 kPa); a chest radiograph was concerning for bibasilar pneumothoraces. ### Vital Signs ### Physical Examination (4 Hours after Birth)

Safety and efficacy of short- and long-term inspiratory muscle training in late-onset Pompe disease (LOPD): a pilot study.

In patients with late-onset Pompe disease, progressive respiratory muscle weakness with predominantly diaphragmatic involvement is a frequent finding at later stages of the disease. Respiratory muscle training (RMT) is an established therapy option for patients with several neuromuscular disorders including Duchenne muscular dystrophy. Forced voluntary muscle contractions of inspiration and/or expiration muscles enhance ventilation by increasing respiratory coordination, endurance, and strength. Efficacy of RMT in LOPD is rarely examined, and the clinical studies performed are difficult to compare because of different training programs and protocols. This impedes a useful statement and recommendation about the safety and efficacy of respiratory muscle training. We conducted a monocentric unblinded single-arm pilot study in patients with LOPD to evaluate the safety and efficacy of inspiratory muscle training (IMT). The primary objective was to determine the efficacy of a 6-week repetitive IMT with a gradual increase of inspiratory resistance, measured by MIP (maximum inspiratory pressure) in the upright position. For statistical analysis, we used an A-B-C singlesubject design. The 6-week training-period A was followed by a 6-week non-training period B and an optional training period of 40 weeks in period C. The total study duration for the periods A, B and C was 52 weeks. Throughout the study, spirometry assessments (FCV, FEV1) and measurements of respiratory strength (MIP, MEP) were performed at defined time points, as well as capillary oximetry and capnometry, motor function test and patient's questionnaires for quality of life and dyspnea, measured by St. George's Respiratory Questionnaire (SGRQ) and MMRC-Dyspnea scale. For the cross-sectional comparison, a paired two-sided t test, and for the longitudinal comparison, a two-sample, two-sided t test were used. When data were not normally distributed, a Wilcoxon-Mann-Whitney test was added. Finally, the annual decline in FVC and FEV1 before and after IMT was compared. 11 subjects were included in this pilot study. Overall, IMT was well tolerated. In four subjects, a total of six adverse events related to the study procedures were noticed. Training compliance was excellent in the first weeks of training, but declined continuously in the extension period. There was a significant increase in our primary outcome measure MIP within the 6-week period of frequent IMT with a mean of 15.7% (p =0.024; d =0.402). A significant increase was also seen after week 52 by a mean of + 26.4% (mean + 13.4 cmH2O, p =0.001, d =0.636). In the 6-week non-training interim-period (period B), the values remained stable, and there was no clinically meaningful decline in secondary outcome measures. The increase in MIP did not have any effect on secondary outcome measures like spirometry tests (FVC, FEV1), capillary blood gas analysis, motor function tests, patient's perceived quality of life or any significant change in dyspnea score. Frequent IMT improves MIP and thereby stabilizes and decelerates the decline of the diaphragm strength. The gradual increase of inspiratory resistance is well tolerated without any increase of side effects, as long as IMT is supervised and resistance is individually adjusted to the patient's perceived grade of exhaustion. Although we could not detect a significant impact on secondary outcome measures, IMT should be offered to all LOPD patients, especially to those who demonstrate a progressive decline in respiratory muscle function or are unable to receive ERT.

PO-037 Validation Of Capillary Blood Gas Analysis For The Assessment Of Training Load In Track Cycling

Objective The energy supply of daily training of track cycling should be mainly by anaerobic metabolism, which can make the blood buffer capacity facing huge Challenge and being improved. The arterialized capillary blood gas analysis can be a reliable method to evaluate the blood status of base-acid balance, which may reflect the effect of exercise intensity on blood buffer system. The paper validate the blood gas analysis as a reliable method for evaluating the total periodical training load of track cyclists.
 Methods Five male and five female elite track cyclists performed two phases (four weeks per phase) of training respectively. The content included the track specific, strength and aerobic training. The Borg's Rating of Perceived Exertion (RPE) Scale (0-11) was recorded in the ten minutes after each session and calculated the session RPE (sRPE). The total inertial load (TIL) was calculated by sRPE sum from Monday to Thursday. The arterialized capillary blood gas analysis was performed at 7:00 AM on Monday and Friday. The delta value (ΔPH, ΔPCO2, ΔTCO2, ΔHCO3-, ΔBE, ΔPO2, ΔSO2) were calculated by Friday minus Monday. Pearson's linear correlation was applied to calculate the correlation between TIL and delta value. Independent t test was used to test the differences between two genders.
 Results There was the moderate correlation between TIL with ΔPH and ΔHCO3- (Correlation Coefficient= 0.712 and 0.642 respectively, P<0.01). But other blood gas indexes didn’t show the obvious relationship with TIL (Correlation Coefficient < 0.5). There was no differences for TIL between male and female (3870.1±788.4 vs. 4130.2±716.7, P>.05). Moreover, ΔHCO3- of male was significant more than female by 95.1% (P<0.01). There were significant correlation between TIL and ΔPH for both male and female (Correlation Coefficient= 0.785 and 0.812 respectively, P<0.01), and between TIL and ΔPH for both male and female (Correlation Coefficient= 0.662 and 0.658 respectively, P<0.01).
 Conclusions The PH value and bicarbonate radical of blood should be sensitive to the high intensity track cycling training, which can be the valid to evaluate the inertial load. However, gender has no influence on evaluating. The oxygen partial pressure and oxygen saturation of blood can not reflect the training load accurately.

Obesity Hypoventilation Syndrome: Early Detection of Nocturnal-Only Hypercapnia in an Obese Population.

Hypoventilation in obesity is now divided into five stages; stage 0 (pure obstructive sleep apnea; OSA), stages I/II (obesity-related sleep hypoventilation; ORSH) and stages III/IV (awake hypercapnia, obesity hypoventilation syndrome; OHS). Hypercapnia during the day may be preceded by hypoventilation during sleep. The goal of this study was to determine the prevalence and to identify simple clinical measures that predict stages I/II ORSH. The effect of supine positioning on selected clinical measures was also evaluated. Ninety-four patients with a body mass index > 40 kg/m2 and a spirometric ratio > 0.7 were randomized to begin testing either in the supine or upright seated position on the day of their diagnostic sleep study. Arterialized capillary blood gases were measured in both positions. Oxygen saturation measured by pulse oximetry was also obtained while awake. Transcutaneous CO2 monitoring was performed during overnight polysomnography. Stages I/II ORSH had a prevalence of 19% in an outpatient tertiary hospital setting compared with 61%, 17%, and 3% for stages 0, III/IV, and no sleep-disordered breathing respectively. Predictors for sleep hypoventilation in this group were an awake oxygen saturation of ≤ 93% (sensitivity 39%, specificity 98%, positive likelihood ratio of 22) and a partial pressure of carbon dioxide ≥ 45 mmHg (sensitivity 44%, specificity 98%, positive likelihood ratio of 24) measured in the supine position. ORSH has a similar prevalence to OHS. Awake oxygen saturation and partial pressure of carbon dioxide performed in the supine position may help predict obese patients with sleep hypoventilation without awake hypercapnia. A commentary on this article appears in this issue on page 1455. Registry: Australian New Zealand Clinical Trials Registry, Identifier: ACTRN 12615000135516, URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367493&isReview=true, Title: A cross-sectional study to identify obese patients who are at risk for developing obesity hypoventilation syndrome (OHS) by investigating the relationship between daytime measures (including supine hypercapnia, distribution of body fat and lung volumes) with the presence of hypoventilation during sleep.

Apparent Life-Threatening Events: Helping Infants Help Themselves.

Apparent life-threatening event (ALTE) refers to a constellation of unexpected events suddenly occurring in infants that extremely alarm the observers. The objectives of this study were to evaluate 1) intervention of Emergency Service (ES) at home, 2) parental behavior before ES intervention, 3) patients' outcome at follow-up of a minimum of 6 months. Retrospective study of infants younger than 12 months whose parents called ES and were evaluated for ALTE from 2005 to 2014. Tactile stimulation (TS) was defined as any maneuver performed by parents or ES staff aimed at rescuing patients without cardiopulmonary resuscitation attempts. Cardiopulmonary resuscitation was defined according to American Heart Association Guidelines 2010. One hundred eighty-eight patients were eligible. Emergency Service provided intervention for 178 infants (10 were assisted only by phone). All patients received TS by parents before ES arrival. Mean time for ES to reach patient location was 15 ± 10 minutes. On examination, 136 patients (76.5%) seemed normal and 42 symptomatic. One hundred sixty-three patients were brought to the emergency department where 23 patients were found symptomatic. One hundred six of 163 patients underwent capillary blood gas determination and, in 28 (26%) of 106, alterations were found. No infant had subsequent cardiopulmonary arrest or clinically evident adverse neurological outcome. Six were found to be epileptic. No infant died during the episode or during follow-up. Our findings suggest that ALTE is an alarming but self-limiting phenomenon that can be resolved either spontaneously or by simple TS in most cases. Emergency Service should solicit patients' physiological responses through TS first while considering a cardiopulmonary resuscitation maneuver.

Impact of Gas Masks on Work of Breathing, Breathing Patterns, and Gas Exchange in Healthy Subjects.

The gas mask is used to protect military and non-military personnel exposed to respiratory hazards (chemical, biologic, radiologic, and nuclear agents). The objective was to evaluate the impact of the gas mask on indexes of respiratory effort and breathing patterns in a human model because no data exist. The design of the study was a crossover evaluation with four 10-min conditions in a randomized order: with and without wearing the gas mask when at rest and when exerting a standardized effort. During the studied conditions, 14 healthy subjects were evaluated for breathing patterns, indexes of respiratory effort (work of breathing, pressure-time product for esophageal pressure, and esophageal pressure swing) and capillary blood gases. Continuous SpO2 was recorded during the tested conditions. The indexes of respiratory effort significantly increased when subjects wore the gas mask under the tested conditions (at rest and during effort). The work of breathing was significantly augmented with the mask (at rest, 0.40 ± 0.32 J/cycle vs 0.25 ± 0.10 J/cycle; effort, 5.96 ± 3.32 J/cycle vs 4.43 ± 2.50 J/cycle; P < .001). The other indexes of effort (esophageal pressure-time product and esophageal swing were all significantly increased, from 30 to 60%, with a gas mask in comparison with at baseline without a gas mask). The impact on breathing patterns and PaCO2 was limited, without significant differences. Moderate hypoxemia was present during effort and was not increased by the gas mask. This study demonstrated a substantial increase in the indicies of respiratory effort both at rest and during exercise with a gas mask. Our measurements and findings may be referred in future research and development studies in this field. (ClinicalTrials.gov registration NCT02782936.).

Predictors of admission in patients with acute Bronchiolitis

Background: Acute viral bronchiolitis represents the most common lower respiratory tract infection in infants and young children less than 24 months and is associated with substantial morbidity and mortality. Respiratory syncytial virus is the most frequently identified virus, but many other viruses may also cause acute bronchiolitis. Most children with bronchiolitis have a self-limiting mild disease and can be safely managed at home with careful attention to feeding and respiratory status. Criteria for referral and admission vary between hospitals as do clinical practice in the management of acute viral bronchiolitis, Supportive care, including administration of oxygen and fluids, is the cornerstone of current treatment. Aim: To identify the epidemiological profile of babies less than 2 years with bronchiolitis, clinical characteristics of babies with bronchiolitis in respect to the main symptoms, signs and clinical presentations and the factors that affect disposition of the patient with acute bronchiolitis. Patient and Method: Design: A prospective observational case series study. Setting: Emergency unit in Al-Khansaa Teaching Hospital. Study period: one-year (1/October/ 2012 – 30/September/ 2013) Sample size: 84 patients were enrolled in this study. Inclusion criteria: 1-first attack of acute wheeze due to bronchiolitis.2-age 2years or younger. Exclusion criteria: 1. patients with more than one attack wheezes.2. wheezes due to other cause (pneumonia).3.age more than 2 years. Result: A Total of 84 patients with 1st attack wheeze in less than 2 years identified. The main age was 8.2±5.77months, and the peak age was 6 months.53 (63.1%) male, and 31(36.9%) female and ratio of 1.7:1.and the majority were mature babies, came from urban area more than rural area. The comparison done concentrated on symptoms, signs, and radiological findings between babies younger and older than 6months age and studied either to hospital or not and concentrated these findings had role as an indicator for admission on heart rate, respiratory rate and SPO2, The results indicated that poor feeding, irritability, runny nose, cough and shortness of breath all of these symptoms consider a good indicators for admission in both age groups. Severe retraction, rhonchi, and temperature more than 38.1 C, all of these physical findings consider good indicators of admission in both age groups. While fine rales and cyanosis are good indicators in babies younger than 6 months only. Radiological findings had no role in assessing admission of the patients to hospital. Respiratory rate (tachypnea)>60 bpm, and SPO2 160 BPM consider significant indicator only in babies older than 6 months of age. Of all 84 patients admitted to emergency unit, only 63(75%) of them were admitted to hospital and the remaining were discharged. Conclusion: Indications of admission can be assessed by many symptoms (poor feeding, irritability, runny nose, cough, and SOB) and physical signs (Rhonchi, severe retraction, temperature >38.1 c, RR>60bpm, and SPO2<94), so We recommended carrying out serial checking SPO2 by pulse oximetry, and to conduct arterial or capillary blood gas analysis for the severely ill patients to assess the severity of the disease and its complications and treatment procedures.

A Single Lab Test to Aid Pierre Robin Sequence Severity Diagnosis.

The workup of patients with Pierre Robin sequence (PRS) consists of a physical examination, O2 saturation, and polysomnography to determine the severity of respiratory obstruction and need for surgery. We suggest that capillary blood gas (CBG) may be a better physiologic representation of airway obstruction and should be routinely used in the management of patients with PRS. This is a multicenter study based on a retrospective review of medical records. The study was performed at tertiary care centers. Patients with PRS <1 year old underwent mandibular distraction osteogenesis. Using successful treatment outcome as a reference standard, receiver operating characteristic (ROC) curve was used to determine the accuracy of the diagnostic test and values for the best sensitivity and specificity to determine the need for surgical intervention. Of 73 patients, 48 had sporadic PRS, 23 had syndromes, 2 had micrognathia, not otherwise specified. Mandibular distraction osteogenesis was performed in 62 patients at a mean age of 39 days. The mean initial Apnea-Hypopnea Index (AHI) in nonsurgical versus surgical groups was 10 versus 31 ( P = .063), pH 7.41 versus 7.34 ( P = .003), pCO2 43 versus 56 ( P < .001), and HCO3 27 versus 30 ( P = .022). The ROC curve showed that pCO2 of 49.5 has the best specificity (100%) and sensitivity (72.6%) profile in terms of need for definitive airway. A simple CBG heel stick may better predict the physiologic effects of obstructive apnea; therefore, it should be added to the algorithm of PRS workup.

Accuracy of Transcutaneous CO2 Values Compared With Arterial and Capillary Blood Gases.

Transcutaneous monitors are utilized to monitor a patient's respiratory status. Some patients have similar values when comparing transcutaneous carbon dioxide (PtcCO2 ) values with blood gas analysis, whereas others show extreme variability. A retrospective review of data was performed to determine how accurately PtcCO2 correlated with CO2 values obtained by arterial blood gas (ABG) or capillary blood gas. To determine whether PtcCO2 values correlated with ABG or capillary blood gas values, subjects' records were retrospectively reviewed. Data collected included the PtcCO2 value at the time of blood gas procurement and the ABG or capillary blood gas PCO2 value. Agreement of pairs of methods (ABG vs PtcCO2 and capillary blood gas vs PtcCO2 ) was assessed with the Bland-Altman approach with limits of agreement estimated with a mixed model to account for serial measurements per subject. A total of 912 pairs of ABG/PtcCO2 values on 54 subjects and 307 pairs of capillary blood gas/PtcCO2 values on 34 subjects were analyzed. The PCO2 range for ABG was 24-106 mm Hg, and PtcCO2 values were 27-133 mm Hg. The PCO2 range for capillary blood gas was 29-108 mm Hg, and PtcCO2 values were 30-103 mm Hg. For ABG/PtcCO2 comparisons, the Pearson correlation coefficient was 0.82, 95% CI was 0.80-0.84, and P was <.001. For capillary blood gas/PtcCO2 comparisons, the Pearson correlation coefficient was 0.77, 95% CI was 0.72-0.81, and P was <.001. For ABG/PtcCO2 , the estimated difference ± SD was -6.79 ± 7.62 mm Hg, and limits of agreement were -22.03 to 8.45. For capillary blood gas/PtcCO2 , the estimated difference ± SD was -1.61 ± 7.64 mm Hg, and limits of agreement were -16.88 to 13.66. The repeatability coefficient was about 30 mm Hg. Based on these data, capillary blood gas comparisons showed less variation and a slightly lower correlation with PtcCO2 than did ABG comparisons. After accounting for serial measurements per patient, due to the wide limits of agreement and poor repeatability, the utility of relying on PtcCO2 readings for this purpose is questionable.

Effects of human relaxin-2 (serelaxin) on hypoxic pulmonary vasoconstriction during acute hypoxia in a sheep model.

PurposeHypoxia induces pulmonary vasoconstriction with a subsequent increase of pulmonary artery pressure (PAP), which can result in pulmonary hypertension. Serelaxin has shown an increase of pulmonary hemodynamic parameters after serelaxin injection. We therefore investigated the response of pulmonary hemodynamic parameters after serelaxin administration in a clinically relevant model.MethodsSix controls and six sheep that received 30 μg/kg serelaxin underwent right heart catheterization during a 12-minute hypoxia period (inhalation of 5% oxygen and 95% nitrogen) and subsequent reoxygenation. Systolic, diastolic, and mean values of both PAP (respectively, PAPs, PAPd, and PAPm) and pulmonary capillary wedge pressure (respectively, PCWPs, PCWPd, and PCWPm), blood gases, heart rate (HR), and both peripheral and pulmonary arterial oxygen saturation were obtained. Cardiac output (CO), stroke volume (SV), pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAcompl), and systemic vascular resistance (SVR) were calculated.ResultsThe key findings of the current study are that serelaxin prevents the rise of PAPs (p≤0.001), PAPm, PCWPm, PCWPs (p≤0.03), and PAPd (p≤0.05) during hypoxia, while it simultaneously increases CO and SV (p≤0.001). Similar courses of decreases of PAPm, PAPd, PAPs, CO, SVR (p≤0.001), and PCWPd (p≤0.03) as compared to hypoxic values were observed during reoxygenation. In direct comparison, the experimental groups differed during hypoxia in regard to HR, PAPm, PVR, and SVR (p≤0.03), and during reoxygenation in regard to HR (p≤0.001), PAPm, PAPs, PAPd, PVR, SVR (p≤0.03), and PCWPd (p≤0.05).ConclusionThe findings of this study suggest that serelaxin treatment improves pulmonary hemodynamic parameters during acute hypoxia.

Correlation and Interchangeability of Venous and Capillary Blood Gases in Non-Critically Ill Neonates.

Venous blood gas (VBG) is frequently used in the neonatal unit as alternative for capillary blood gas (CBG). However, studies reporting correlation are conflicting and data on interchangeability in neonates are lacking. We investigated the correlation and interchangeability of the components between VBG and CBG in infants admitted to the neonatal intensive care unit. In a prospective study in the neonatal unit in Leiden University Medical Center (Netherlands), simultaneously VBG and CBG were withdrawn in neonates when both venous puncture and intravenous access as blood gas monitoring was indicated. From each blood gas analysis, a Pearson correlation, intraclass correlation, and Bland-Altman analysis was performed. Clinically acceptable difference for each blood gas value was defined up-front by means of an absolute difference: pH ± 0.05; partial pressure of carbon dioxide (pCO2) (±0.67 kPa = 5 mmHg); partial pressure of oxygen (pO2) (±0.67 kPa = 5 mmHg); base excess ± 3 mmol/l; and bicarbonate (HCO3-) ± 3 mmol/l. In 93 patients [median gestational age 31 (IQR 29-34) weeks], 193 paired samples of VBG and CBG were collected. The Pearson correlation between VBG and CBG was very strong for pH (r = 0.79; P < 0.001), BE (r = 0.90; P < 0.001) and bicarbonate (r = 0.87; P < 0.001); strong for pCO2 (r = 0.68; P < 0.001); and moderate for pO2 (r = 0.31; P < 0.001). The percentage of the interchangeability within our acceptable absolute difference for pH was 88%, pCO2 72%, pO2 55%, BE 90%, and bicarbonate 94%. VBG and CBG in neonates are well correlated and mostly interchangeable, except for pO2.

High altitude arterialised capillary earlobe blood gas measurement using the Abbott i-STAT

IntroductionMeasurement of physiological parameters in extreme environments is essential to advancing knowledge, prophylaxis and treatment of altitude sickness. Point-of-care testing facilitates investigation in non-specialist and remote settings, as well as...

Acute bronchodilator therapy does not reduce wasted ventilation during exercise in COPD

This randomized, double-blind, crossover study aimed to determine if acute treatment with inhaled bronchodilators, by improving regional lung hyperinflation and ventilation distribution, would reduce dead space-to-tidal volume ratio (VD/VT); thus contributing to improved exertional dyspnea in COPD.Twenty COPD patients (FEV1 = 50 ± 15% predicted; mean ± SD) performed pulmonary function tests and symptom-limited constant-work rate exercise at 75% peak-work rate (with arterialized capillary blood gases) after nebulized bronchodilator (BD; ipratropium 0.5mg + salbutamol 2.5 mg) or placebo (PL; normal saline).After BD versus PL: Functional residual capacity decreased by 0.4L (p = .0001). Isotime during exercise after BD versus PL (p < .05): dyspnea decreased: 1.2 ± 1.9 Borg-units; minute ventilation increased: 3.8 ± 5.5 L/min; IC increased: 0.24 ± 0.28 L and VT increased 0.19 ± 0.16 L. There was no significant difference in arterial CO2 tension or VD/VT, but alveolar ventilation increased by 3.8 ± 5.5 L/min (p = .02). Post-BD improvements in respiratory mechanics explained 51% of dyspnea reduction at a standardized exercise time.Bronchodilator-induced improvements in respiratory mechanics were not associated with reduced wasted ventilation – a residual contributory factor to exertional dyspnea during exercise in COPD.

Influence of dietary nitrate supplementation on lung function and exercise gas exchange in COPD patients

BackgroundDuring exercise as pulmonary blood flow rises, pulmonary capillary blood volume increases and gas exchange surface area expands through distention and recruitment. We have previously demonstrated that pulmonary capillary recruitment is limited in COPD patients with poorer exercise tolerance. Hypoxia and endothelial dysfunction lead to pulmonary vascular dysregulation possibly in part related to nitric oxide related pathways. PurposeTo determine if increasing dietary nitrate might influence lung surface area for gas exchange and subsequently impact exercise performance. MethodsSubjects had stable, medically treated COPD (n = 25), gave informed consent, filled out the St George Respiratory Questionnaire (SGRQ), had a baseline blood draw for Hgb, performed spirometry, and had exhaled nitric oxide (exNO) measured. Then they performed the intra-breath (IB) technique for lung diffusing capacity for carbon monoxide (DLCO) as well as pulmonary blood flow (Qc). Subsequently they completed a progressive semi-recumbent cycle ergometry test to exhaustion with measures of oxygen saturation (SpO2) and expired gases along with DLCO and Qc measured during the 1st work load only. Subjects were randomized to nitrate supplement group (beetroot juice) or placebo group (black currant juice) for 8 days and returned for repeat of the above protocol. ResultsExhaled nitric oxide levels rose >200% in the nitrate group (p < 0.05) with minimal change in placebo group. The SGRQ suggested a small fall in perceived symptom limitation in the nitrate group, but no measure of resting pulmonary function differed post nitrate supplementation. With exercise, there was no influence of nitrate supplementation on peak VO2 or other measures of respiratory gas exchange. There was a tendency for the exercise DLCO to increase slightly in the nitrate group with a trend towards a rise in the DLCO/Qc relationship (p = 0.08) but not in the placebo group. The only other significant finding was a fall in the exercise blood pressure in the nitrate group, but not placebo group (p < 0.05). ConclusionDespite evidence of a rise in exhaled nitric oxide levels with nitrate supplementation, there was minimal evidence for improvement in exercise performance or pulmonary gas exchange surface area in a stable medically treated COPD population.

Case 2: Refractory Respiratory Failure and Pneumothorax in a Full-Term Newborn

A female infant with a birthweight of 2,925 g is delivered at 38 6/7 weeks of gestation by a 32-year-old gravida 1, para 1 mother. The pregnancy is uncomplicated, and the mother’s evaluation for infection before delivery is negative. The birth occurs via precipitous vaginal delivery and is uneventful except for terminal meconium. At delivery, the infant is initially vigorous with an appropriate heart rate and tone, but she subsequently requires resuscitation because of increased work of breathing and oxygen saturation in the low 60s. She is treated with positive pressure ventilation, and the fraction of inspired oxygen is increased to 100%. Despite positive pressure ventilation, her physical examination findings and oxygen saturation do not improve. Her 1- and 5-minute Apgar scores are 7 each. Initial chest radiography shows a right-sided pneumothorax and pneumomediastinum. Her first capillary blood gas is notable for a pH of 6.9, a partial pressure of carbon dioxide (Pco2) of 101 mm Hg (13.4 kPa), and a base deficit of 13. Needle decompression of the right chest is attempted, after which the infant is intubated and mechanical ventilation is started. Screening infectious laboratory tests are performed and empirical broad-spectrum antibiotics are started. The infant is then transferred to a tertiary care facility for further care. Upon arrival, the infant is switched to a high-frequency oscillator. At this point, repeat chest radiography shows bilateral pneumothoraces and pneumomediastinum, so bilateral chest tubes are …

Effects of High-Flow Nasal Cannula on the Work of Breathing in Patients Recovering From Acute Respiratory Failure.

High-flow nasal cannula is increasingly used in the management of respiratory failure. However, little is known about its impact on respiratory effort, which could explain part of the benefits in terms of comfort and efficiency. This study was designed to assess the effects of high-flow nasal cannula on indexes of respiratory effort (i.e., esophageal pressure variations, esophageal pressure-time product/min, and work of breathing/min) in adults. A randomized controlled crossover study was conducted in 12 patients with moderate respiratory distress (i.e., after partial recovery from an acute episode, allowing physiologic measurements). Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada. Twelve adult patients with respiratory distress symptoms were enrolled in this study. Four experimental conditions were evaluated: baseline with conventional oxygen therapy and high-flow nasal cannula at 20, 40, and 60 L/min. The primary outcomes were the indexes of respiratory effort (i.e., esophageal pressure variations, esophageal pressure-time product/min, and work of breathing/min). Secondary outcomes included tidal volume, respiratory rate, minute volume, dynamic lung compliance, inspiratory resistance, and blood gases. Esophageal pressure variations decreased from 9.8 (5.8-14.6) cm H2O at baseline to 4.9 (2.1-9.1) cm H2O at 60 L/min (p = 0.035). Esophageal pressure-time product/min decreased from 165 (126-179) to 72 (54-137) cm H2O • s/min, respectively (p = 0.033). Work of breathing/min decreased from 4.3 (3.5-6.3) to 2.1 (1.5-5.0) J/min, respectively (p = 0.031). Respiratory pattern variables and capillary blood gases were not significantly modified between experimental conditions. Dynamic lung compliance increased from 38 (24-64) mL/cm H2O at baseline to 59 (43-175) mL/cm H2O at 60 L/min (p = 0.007), and inspiratory resistance decreased from 9.6 (5.5-13.4) to 5.0 (1.0-9.1) cm H2O/L/s, respectively (p = 0.07). High-flow nasal cannula, when set at 60 L/min, significantly reduces the indexes of respiratory effort in adult patients recovering from acute respiratory failure. This effect is associated with an improvement in respiratory mechanics.

Variability in Usual Care Mechanical Ventilation for Pediatric Acute Respiratory Distress Syndrome: Time for a Decision Support Protocol?

Although pediatric intensivists philosophically embrace lung protective ventilation for acute lung injury and acute respiratory distress syndrome, we hypothesized that ventilator management varies. We assessed ventilator management by evaluating changes to ventilator settings in response to blood gases, pulse oximetry, or end-tidal CO2. We also assessed the potential impact that a pediatric mechanical ventilation protocol adapted from National Heart Lung and Blood Institute acute respiratory distress syndrome network protocols could have on reducing variability by comparing actual changes in ventilator settings to those recommended by the protocol. Prospective observational study. Eight tertiary care U.S. PICUs, October 2011 to April 2012. One hundred twenty patients (age range 17 d to 18 yr) with acute lung injury/acute respiratory distress syndrome. Two thousand hundred arterial and capillary blood gases, 3,964 oxygen saturation by pulse oximetry, and 2,757 end-tidal CO2 values were associated with 3,983 ventilator settings. Ventilation mode at study onset was pressure control 60%, volume control 19%, pressure-regulated volume control 18%, and high-frequency oscillatory ventilation 3%. Clinicians changed FIO2 by ±5 or ±10% increments every 8 hours. Positive end-expiratory pressure was limited at ~10 cm H2O as oxygenation worsened, lower than would have been recommended by the protocol. In the first 72 hours of mechanical ventilation, maximum tidal volume/kg using predicted versus actual body weight was 10.3 (8.5-12.9) (median [interquartile range]) versus 9.2 mL/kg (7.6-12.0) (p < 0.001). Intensivists made changes similar to protocol recommendations 29% of the time, opposite to the protocol's recommendation 12% of the time and no changes 56% of the time. Ventilator management varies substantially in children with acute respiratory distress syndrome. Opportunities exist to minimize variability and potentially injurious ventilator settings by using a pediatric mechanical ventilation protocol offering adequately explicit instructions for given clinical situations. An accepted protocol could also reduce confounding by mechanical ventilation management in a clinical trial.

High prevalence of COPD in atherosclerosis patients.

Atherosclerosis and COPD are both systemic inflammatory diseases that may influence each other. The aim of the present study was to determine the prevalence of COPD in patients with cerebral and/or peripheral artery disease and to assess factors associated with the presence of COPD. Following the diagnosis of cerebral and/or peripheral artery disease by means of duplex sonography, 166 consecutive patients underwent body plethysmography with capillary blood gas analysis. Thereafter, blood tests with determination of different parameters such as lipid profile, inflammatory and coagulation markers were conducted in remaining 136 patients who fulfilled inclusion criteria of the study. Thirty-six out of 136 patients suffered from COPD, mostly in early stages of the disease. Residual volume indicating emphysema was increased (162.9%±55.9% vs 124.5%±37.0%, p<0.05) and diffusion capacity was decreased (55.1%±19.5% vs 75.3%±18.6%, p<0.05) in COPD patients vs non-COPD group. In capillary blood gas analysis, COPD patients had lower partial pressure of oxygen (70.9±11.5 vs 75.2±11.0 mmHg, p<0.05) and higher partial pressure of carbon dioxide (36.8±7.5 vs 34.4±4.4 mmHg, p<0.05) compared with non-COPD individuals. Presence of COPD was associated with predominance of diabetes mellitus, interleukin-8-related systemic neutrophilic inflammation and anemia. In conclusion, COPD is highly prevalent in patients with atherosclerotic artery disease.