Maternal pre-pregnancy body mass index and foetal acidosis in vaginal and caesarean deliveries: The Japan Environment and Children's Study.

A high maternal body mass index (BMI) is associated with increased risks of asphyxia-related neonatal morbidity. We evaluated the association between maternal pre-pregnancy BMI and foetal acidosis while accounting for the mode of delivery. Participants from the Japan Environment and Children's Study with singleton pregnancies after 22 weeks of gestation who gave birth during 2011-2014 were included. The participants (n = 71,799) were categorised into five groups according to the pre-pregnancy BMI: G1 (BMI < 18.5 kg/m2), G2 (18.5 to < 20.0 kg/m2), G3 (20.0 to < 23.0 kg/m2), G4 (23.0 to < 25.0 kg/m2), and G5 (≥ 25.0 kg/m2). Foetal acidosis was defined as umbilical artery pH (UmA-pH) < 7.20 or < 7.10. Multiple logistic regression analyses were used to evaluate the effect of pre-pregnancy BMI on foetal acidosis risk, accounting for the mode of delivery. In Japanese women, pre-pregnancy BMI ≥ 25.0 kg/m2 significantly increased the likelihood of foetal acidosis in newborns delivered vaginally. We found no association between pre-pregnancy BMI and foetal acidosis in newborns delivered via caesarean section. Counselling for body weight control before pregnancy and adequate management and selection of the mode of delivery in pregnant women with a high BMI who are in labour may be essential to avoid foetal acidosis.

OUTPATIENT ANALYTIC ASSESSMENT OF ANOREXIA NERVOSA - THE IMPORTANCE OF VENOUS BLOOD GASES.

OBJECTIVE: To evaluate serum biochemical parameters' evolution, especially venous blood gas (VBG), in anorexia nervosa (AN), correlating with clinical parameters. METHODS: Retrospective study including out-patient AN adolescents, between January 2014 and May 2017. Three evaluations were compared: t1) first consultation; t2) consultation with the lowest body mass index (BMI) z-score and t3) with the highest BMI z-score. RESULTS: A total of 24 adolescents (87.5% females) were included, mean age of presentation of 14.9±1.7 years, onset of symptoms 6.4±3.2 months before the first visit. In t1, BMI z-score of -1.91±1.11 kg/m2 and ideal weight % of 84.3±9.2. Amenorrhea was present in 88%. In t2 the analytical alterations were: altered VBG in 100%, altered ferritin (72% elevated), altered thyroid function (53% with thyroxine decrease), dyslipidemia (31% elevation of high density lipoprotein, 25% hypercholesterolemia), elevation of urea (25%), elevation of alanine aminotransferase (14%), hypoglycemia (14%), anemia (9%). Respiratory acidosis was present in 91% in t1, 100% in t2 and 94% in t3. There was a significant decrease between t2 and t3 in mean pCO2 (57.2 versus 53.6 mmHg; p=0.009) and mean HCO3 (30.0 versus 28.8 mEq/L; p=0.023). CONCLUSIONS: Respiratory acidosis and increased ferritin were common in this group. Respiratory acidosis was the most frequent abnormality with significant pCO2 and HCO3 variation in the recovery phase. VBG should be considered in AN evaluation, once it seems to be important in assessing the severity of the disease and its subsequent follow-up.

Outpatient analytic assessment of anorexia nervosa — the importance of venous blood gases / Avaliação laboratorial em ambulatório na anorexia nervosa: a importância da gasometria venosa

ABSTRACT Objective: To evaluate serum biochemical parameters' evolution, especially venous blood gas (VBG), in anorexia nervosa (AN), correlating with clinical parameters. Methods: Retrospective study including out-patient AN adolescents, between January 2014 and May 2017. Three evaluations were compared: t1) first consultation; t2) consultation with the lowest body mass index (BMI) z-score and t3) with the highest BMI z-score. Results: A total of 24 adolescents (87.5% females) were included, mean age of presentation of 14.9±1.7 years, onset of symptoms 6.4±3.2 months before the first visit. In t1, BMI z-score of -1.91±1.11 kg/m2 and ideal weight % of 84.3±9.2. Amenorrhea was present in 88%. In t2 the analytical alterations were: altered VBG in 100%, altered ferritin (72% elevated), altered thyroid function (53% with thyroxine decrease), dyslipidemia (31% elevation of high density lipoprotein, 25% hypercholesterolemia), elevation of urea (25%), elevation of alanine aminotransferase (14%), hypoglycemia (14%), anemia (9%). Respiratory acidosis was present in 91% in t1, 100% in t2 and 94% in t3. There was a significant decrease between t2 and t3 in mean pCO2 (57.2 versus 53.6 mmHg; p=0.009) and mean HCO3 (30.0 versus 28.8 mEq/L; p=0.023). Conclusions: Respiratory acidosis and increased ferritin were common in this group. Respiratory acidosis was the most frequent abnormality with significant pCO2 and HCO3 variation in the recovery phase. VBG should be considered in AN evaluation, once it seems to be important in assessing the severity of the disease and its subsequent follow-up.

RESUMO Objetivo: Avaliar a evolução laboratorial, particularmente da gasometria venosa, na anorexia nervosa (AN), correlacionando os achados com parâmetros clínicos. Métodos: Estudo retrospetivo com adolescentes com AN seguidos em ambulatório, entre janeiro de 2014 e maio de 2017. Foram comparadas três avaliações: (t1) primeira consulta; (t2) consulta com escore Z de índice de massa corpórea (IMC) mais baixo; e (t3) consulta com escore Z de IMC mais elevado. Resultados: Incluídos 24 adolescentes, 87,5% do sexo feminino, idade média de apresentação de 14,9±1,7 anos, início dos sintomas 6,4±3,2 meses antes da primeira consulta. Em t1, escore Z de IMC de -1,91±1,11 kg/m2 e % de peso ideal de 84,3±9,2. Tinham amenorreia 88%. Em t2 as alterações laboratoriais encontradas foram: gasometria venosa alterada em 100%, ferritina alterada (72% elevada), função tiroideia alterada (53% com diminuição da tiroxina), dislipidemia (31% com elevação de lipoproteína de alta densidade, 25% com hipercolesterolemia), elevação da ureia (25%), elevação da alanina aminotransferase (14%), hipoglicemia (14%) e anemia (9%). A acidose respiratória esteve presente em 91% em t1, 100% em t2 e 94% em t3. Verificou-se diminuição significativa entre t2 e t3 da pressão parcial de CO2 (pCO2) média (57,2 versus 53,6 mmHg; p=0,009) e HCO3 médio (30,0 versus 28,8 mEq/L; p=0,023). Conclusões: A acidose respiratória e o aumento da ferritina foram comuns nesse grupo. Acidose respiratória foi a alteração mais frequente, com variação significativa de pCO2 e HCO3 na fase de recuperação. A gasometria venosa deve ser considerada na avaliação laboratorial na AN, pois parece ser importante na avaliação da gravidade e monitorização da doença.

Oxygen alert wristbands (OxyBand) and controlled oxygen: a pilot study.

Despite the introduction of Oxygen Alert Cards, guidelines and audits, oxygen therapy remains overused in NHS practice, and this may lead to iatrogenic mortality. This pilot study aimed to examine the use of Oxygen Alert Wristbands (OxyBand) designed to alert health professionals who are delivering oxygen to patients to ensure that the oxygen is administered and titrated safely to the appropriate target saturations. Patients at risk of hypercapnic acidosis were asked to wear OxyBands while presenting to paramedics and health professionals in hospitals. Inappropriate prescription of oxygen reduced significantly after the OxyBands were used. A questionnaire-based assessment showed that the clinicians involved had a good understanding of the risks of uncontrolled oxygen. Forty-two patients found the wrist band comfortable to wear, and only two did not. OxyBands may have the potential to improve patient safety over Oxygen Alert Cards.

Study of Acid-Base Disorders and Biochemical Findings of Patients in a Tertiary Care Hospital: A Descriptive Cross-sectional Study.

INTRODUCTION: Acid base disorder is a condition characterized by alteration in blood pH by the imbalance between the components of blood leading to a life threatening situation. The main aim of this study was to find the prevalence of acid-base disorders and biochemical findings of such disorders in patients in a tertairy care hospital. METHODS: This descriptive cross-sectional study was conducted in Nobel Medical College Teaching Hospital from 1st September, 2018 to 31st August, 2019. Ethical apporoval was taken from Institutional Review Committee. All the patients presented to emergency department, intensive care units and wards were included during the study period. Data were entered and calculations were done in Microsoft Excel, point estimate at 95% Confidence Interval was calculated along with frequency and proportion for binary data. RESULTS: Out of arterial blood gas analysis of 1144 patients, the prevalence of acid base disorders was 718 (62.76%) at 95% Confidence Interval (59.96-65.56%). Simple and mixed acid base disorders were observed in 332 (46.24%) and 386 (53.76%) patients respectively. Respiratory alkalosis was most common among 134 (40.36%) cases in simple acid base disorder whereas metabolic acidosis and respiratory alkalosis was most common among 204 (52.85%) in mixed acid base disorder. All types of disorders were observed more in elderly people (41-60 and >60 age group) than other age groups. CONCLUSIONS: Acid base disorder was found to be more common in very ill patients in emergency and intensive care units. Mixed acid base disorder was the most common with male and elderly patients in predominance.

Association of Hypercapnia and Hypercapnic Acidosis With Clinical Outcomes in Mechanically Ventilated Patients With Cerebral Injury.

Importance: Clinical studies investigating the effects of hypercapnia and hypercapnic acidosis in acute cerebral injury are limited. The studies performed so far have mainly focused on the outcomes in relation to the changes in partial pressure of carbon dioxide and pH in isolation and have not evaluated the effects of partial pressure of carbon dioxide and pH in conjunction. Objective: To review the association of compensated hypercapnia and hypercapnic acidosis during the first 24 hours of intensive care unit admission on hospital mortality in adult mechanically ventilated patients with cerebral injury. Design, Setting, and Participants: Multicenter, binational retrospective review of patients with cerebral injury (traumatic brain injury, cardiac arrest, and stroke) admitted to 167 intensive care units in Australia and New Zealand between January 2000 and December 2015. Patients were classified into 3 groups based on combination of arterial pH and arterial carbon dioxide (normocapnia and normal pH, compensated hypercapnia, and hypercapnic acidosis) during the first 24 hours of intensive care unit stay. Main Outcomes and Measures: Hospital mortality. Results: A total of 30 742 patients (mean age, 55 years; 21 827 men [71%]) were included. Unadjusted hospital mortality rates were highest in patients with hypercapnic acidosis. Multivariable logistic regression analysis and Cox proportional hazards analysis in 3 diagnostic categories showed increased odds of hospital mortality (cardiac arrest odds ratio [OR], 1.51; 95% CI, 1.34-1.71; stroke OR, 1.43; 95% CI, 1.27-1.6; and traumatic brain injury OR, 1.22; 95% CI, 1.06-1.42; P <.001) and hazard ratios (HR) (cardiac arrest HR, 1.23; 95% CI, 1.14-1.34; stroke HR, 1.3; 95% CI, 1.21-1.4; traumatic brain injury HR, 1.13; 95% CI, 1-1.27), in patients with hypercapnic acidosis compared with normocapnia and normal pH. There was no difference in mortality between patients who had compensated hypercapnia compared with patients who had normocapnia and normal pH. In patients with hypercapnic acidosis, the adjusted OR of hospital mortality increased with increasing partial pressure of carbon dioxide, while no such increase was noted in patients with compensated hypercapnia. Conclusions and Relevance: Hypercapnic acidosis was associated with increased risk of hospital mortality in patients with cerebral injury. Hypercapnia, when compensated to normal pH during the first 24 hours of intensive care unit admission, may not be harmful in mechanically ventilated patients with cerebral injury.

A multicentre, randomised controlled, non-inferiority trial, comparing nasal high flow with nasal continuous positive airway pressure as primary support for newborn infants with early respiratory distress born in Australian non-tertiary special care nurseries (the HUNTER trial): study protocol.

INTRODUCTION: Nasal high-flow (nHF) therapy is a popular mode of respiratory support for newborn infants. Evidence for nHF use is predominantly from neonatal intensive care units (NICUs). There are no randomised trials of nHF use in non-tertiary special care nurseries (SCNs). We hypothesise that nHF is non-inferior to nasal continuous positive airway pressure (CPAP) as primary support for newborn infants with respiratory distress, in the population cared for in non-tertiary SCNs. METHODS AND ANALYSIS: The HUNTER trial is an unblinded Australian multicentre, randomised, non-inferiority trial. Infants are eligible if born at a gestational age ≥31 weeks with birth weight ≥1200 g and admitted to a participating non-tertiary SCN, are <24 hours old at randomisation and require non-invasive respiratory support or supplemental oxygen for >1 hour. Infants are randomised to treatment with either nHF or CPAP. The primary outcome is treatment failure within 72 hours of randomisation, as determined by objective oxygenation, apnoea or blood gas criteria or by a clinical decision that urgent intubation and mechanical ventilation, or transfer to a tertiary NICU, is required. Secondary outcomes include incidence of pneumothorax requiring drainage, duration of respiratory support, supplemental oxygen and hospitalisation, costs associated with hospital care, cost-effectiveness, parental stress and satisfaction and nursing workload. ETHICS AND DISSEMINATION: Multisite ethical approval for the study has been granted by The Royal Children's Hospital, Melbourne, Australia (Trial Reference No. 34222), and by each participating site. The trial is currently recruiting in eight centres in Victoria and New South Wales, Australia, with one previous site no longer recruiting. The trial results will be published in a peer-reviewed journal and will be presented at national and international conferences. TRIAL REGISTRATION NUMBER: Australian and New Zealand Clinical Trials Registry (ANZCTR): ACTRN12614001203640; pre-results.

Mortalidad en el síndrome de obesidad-hipoventilación y factores de riesgo pronóstico / Mortality in obesity-hypoventilation syndrome and prognostic risk factors

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Ventilación mecánica no invasiva en ancianos con insuficiencia cardíaca aguda / Non invasive ventilation in elderly with acute heart failure

OBJETIVO: comprobar la utilidad de la ventilación mecánica no invasiva (VMNI) en ancianos que ingresan en una Unidad de Monitorización Respiratoria (UMR) en situación de acidosis respiratoria secundaria a insuficiencia cardíaca. MÉTODOS: estudio prospectivo observacional, realizado en el Hospital Universitario La Princesa (Madrid), durante el periodo comprendido entre octubre del 2009 y diciembre del 2012. Se incluyeron a 42 pacientes ancianos (≥ 70 años) con diagnóstico de ingreso de insuficiencia cardíaca y acidosis respiratoria (pH < 7,35 y PaCO2 > 45 mm Hg). RESULTADOS: el 62% fueron mujeres. La edad media fue de 78,2 años. El índice de Charlson fue de 3,41 y la media de fármacos/día 5,8. El pH al ingreso fue de 7,24 (7,19 en el grupo que fallecieron) y una PaCO2 de 83,1 mm Hg (88,7 mm Hg en el grupo exitus). Las principales complicaciones durante el ingreso fueron cardiovasculares. La tasa de exitus fue del 25%. La principal causa de reingreso fue la insuficiencia cardíaca y la supervivencia global fue del 60%.CONCLUSIÓN: la VMNI es útil en el tratamiento de pacientes ancianos con insuficiencia cardíaca. Los principales factores asociados a mortalidad fueron: bajo pH y alta PaCO2 al ingreso, frecuencia respiratoria alta y mala situación basal

OBJECTIVE: the aim of the study was to determine the usefulness of non-invasive ventilation (NIV) in elderly with multiple comorbidities that were taken to hospital with respiratory acidosis due to heart failure and survivor after one year follow-up. METHOD: observational prospective trial made at the Hospital Universitario La Princesa (Madrid) between 2009 th october and 2012 th december. We included 42 elderly patients with heart failure and respiratory acidosis that needed NIV. RESULTS: 62% was women. The median age was 78,2 years. Charlson Index was 3,41 and the median of drugs that patients taken was about 5,8. The main complication during income was cardiovascular disease. 25% died during admission. The principal diagnosed of re-admission was heart failure. Global survivor was 60%. CONCLUSIONS: NIV is a good treatment for elderly patients with heart failure and non-intubation orders. The principal factors associated with mortality were: low pH and high PaCO2 at emergency department, high respiratory frequency and bad basal situation

Early respiratory acidosis is a new risk factor for pneumonia after lung resection.

Postoperative pneumonia (POP) is a life-threatening complication of lung resection (LR). Its risk factors, bacteriological profile and outcome are not well known. The aims of this study were to describe the outcome and causal bacteria and to identify risk factors for POP. We reviewed all cases admitted to intensive care after LR. Clinical parameters, operative and postoperative data were recorded. POP was suspected on the basis of fever, radiographic infiltrate, and either leucocytosis or purulent sputum. The diagnosis was confirmed by culture of a respiratory sample. Risk factors for POP were identified by univariate and multivariate analysis. We included 159 patients in this study. POP was diagnosed in 23 patients (14.4%) and was associated with a higher hospital mortality rate (30% versus 5%, P = 0.0007) and a longer hospital stay. Members of the Enterobacteriaceae and Pseudomonas species were the most frequently identified pathogens. Early respiratory acidosis (ERA; OR, 2.94; 95% CI, 1.1-8.1), blood transfusion (OR, 3.8; 95% CI, 1.1-13.1), bilobectomy (OR, 7.26; 95% CI, 1.2-43.1) and smoking history (OR, 1.84; 95% CI, 1.1-3) were identified as independent risk factors. ERA may be a risk factor for POP and could serve as a target for therapeutic interventions.

Alcohol intoxication among Dutch adolescents: acute medical complications in the years 2000-2010.

OBJECTIVE: To investigate acute medical complications of alcohol intoxication among adolescents presenting to Reinier de Graaf Hospital, a major nonacademic hospital in Delft, the Netherlands. METHODS: The frequency of reduced consciousness, hypothermia, electrolyte disturbances, hypoglycemia, and acidosis along with alcohol intoxication was retrospectively studied in the medical records of patients aged 11 to 17 years admitted between January 1, 2000, and April 30, 2010. RESULTS: Reduced consciousness (45%) and hypothermia (43.1%) were the most common clinical findings. More boys than girls experienced hypothermia (P = .028), probably because of the higher blood alcohol concentration level ( P = .026), which was associated with lower temperature (Pearson's r = -.37; P < .001). The most frequent electrolyte disturbance was hyperchloremia (31.1%), followed by low bicarbonate (22%), hypokalemia (11.9%), and hypernatremia (7.7%). Strikingly, none of the patients in this study suffered hypoglycemia. On the contrary, 13.6% of the patients were slightly hyperglycemic. Mild acidosis, both metabolic and respiratory, was observed among 28.8% of the patients, although the metabolic component predominated. CONCLUSIONS: Acute medical complications because of alcohol intoxication appeared to be mild, and most remarkably none of the patients experienced hypoglycemia.

A randomized controlled trial of post-extubation bubble continuous positive airway pressure versus Infant Flow Driver continuous positive airway pressure in preterm infants with respiratory distress syndrome.

OBJECTIVE: To compare the efficacy and safety of bubble continuous positive airway pressure (CPAP) and Infant Flow Driver (IFD) CPAP for the post-extubation management of preterm infants with respiratory distress syndrome (RDS). STUDY DESIGN: A total of 140 preterm infants at 24 to 29 weeks' gestation or with a birth weight of 600 to 1500 g who were ventilated at birth for RDS were randomized to receive either IFD CPAP (a variable-flow device) or bubble CPAP (a continuous-flow device). A standardized protocol was used for extubation and CPAP. No crossover was allowed. The primary outcome was successful extubation maintained for at least 72 hours. Secondary outcomes included successful extubation maintained for 7 days, total duration of CPAP support, chronic lung disease, and complications of prematurity. RESULTS: Seventy-one infants were randomized to bubble CPAP, and 69 were randomized to IFD CPAP. Mean gestational age and birth weight were similar in the 2 groups, as were the proportions of infants who achieved successful extubation for 72 hours and for 7 days. However, the median duration of CPAP support was 50% shorter in the infants on bubble CPAP. Moreover, in the subset of infants who were ventilated for less than 14 days, the infants on bubble CPAP had a significantly lower extubation failure rate. There was no difference in the incidence of chronic lung disease or other complications between the 2 study groups. CONCLUSIONS: Bubble CPAP is as effective as IFD CPAP in the post-extubation management of infants with RDS; however, in infants ventilated for < or = 14 days, bubble CPAP is associated with a significantly higher rate of successful extubation. Bubble CPAP also is associated with a significantly reduced duration of CPAP support.

[Use of capnography in acute gastroenteritis]. / Utilidad del empleo de la capnografía en la gastroenteritis aguda.

OBJECTIVE: End-tidal carbon dioxide (PetCO(2)) is a good predictor of circulation and metabolism. There are different studies that suggest PetCO(2) monitoring is a valuable and reliable tool to follow acidosis in pediatric patients with diabetic ketoacidosis. Acute gastroenteritis can cause acidosis, therefore, capnography could be useful in these situations. The objective was to determine the relationship between PetCO(2) and bicarbonate (HCO3) in pediatric patients with acute gastroenteritis and acidosis. METHODS: Clinical, prospective, observational study from April 2006 to January 2007. Children with acute gastroenteritis and dehydration and pH < 7.30 and HCO3 < 20 meq/L in laboratory tests were included. Exclusion criteria included patients with not well tolerated capnography and respiratory illness. Initial and post treatment PetCO(2) and HCO3 were collected as well as demographic data, physical examination data, laboratory tests and hospitalization data. RESULTS: Twenty-five children were included in the final analysis (10 female, 15 male). The mean age was 11.6 + 10 months (1-144 months). The correlation between PetCO(2) and serum bicarbonate was statistically significant with a Pearson's correlation coefficient of r = 0.61 for initial values and r = 0.75 for post treatment values. CONCLUSIONS: Capnography offers a noninvasive measurement of acidosis in pediatric patients with acute gastroenteritis and dehydration.

Consequences of intrauterine acidosis for early morbidity of term newborn infants.

OBJECTIVES: The study was designed to evaluate early morbidity of term newborn infants according to the umbilical artery pH and umbilical artery base excess. STUDY DESIGN: The study was based on the 1 173 infants who were born at term in the study period in 1997 with a UA-pH below 7.20. A retrospective review was carried out of maternal and infant records during the study period. All data were evaluated using SPSS for windows. RESULTS: Apgar-values and UA-pH correlated closely, the rate of 1-minute Apgar scores < 7 increased with decreasing UA-pH. The rate of 5-minute Apgar score < 7 increased strongly with UA-pH below 7.00. The study showed how closely UA-pH values are related to UA-BE values. Of newborns with UA-BE values of 0 to - 9 mmol / l 7 % had 1-minute Apgar scores < 7, 53 % of cases with UA-BE

Influence of slight to moderate risk for birth hypoxia on acquisition of cognitive and language function in the preterm infant: a cross-sectional comparison with preterm-birth controls.

The cognitive and language performance of a group of 26 preterm-birth preschool and early school-age children with slight to moderate risk for perinatal hypoxia was compared with the performance of a preterm-birth comparison group of 26 children. Despite the relatively small discrepancy in degree of risk, the cognitive performance of the 2 groups diverged significantly. When data for children with known perinatal arterial pH were combined, a curvilinear (quadratic) regression model provided the best fit. Increasing acidosis was linearly related to decreases in cognitive skills, with the bend in the curve occurring well within the normal range of pH values. Hence, in the preterm infant, even minor risk for birth hypoxia may result in discernible deviation from the expected developmental trajectory.

One year period prevalence study of respiratory acidosis in acute exacerbations of COPD: implications for the provision of non-invasive ventilation and oxygen administration.

BACKGROUND: Non-invasive ventilation (NIV) reduces mortality and intubation rates in patients with chronic obstructive pulmonary disease (COPD) admitted to hospital with respiratory acidosis. This study aimed to determine the prevalence of respiratory acidosis in patients admitted with COPD, to draw inferences about oxygen therapy, and to determine the need for NIV services for acute COPD in typical UK hospitals. METHODS: This one year prospective prevalence study identified patients with COPD aged 45-79 years inclusive who were admitted to Leeds General Infirmary, St James's University, and Killingbeck Hospitals, Leeds between 1 March 1997 and 28 February 1998. The prevalence of respiratory acidosis and the relationship with oxygenation are described. Other outcomes included intensive care use and in hospital mortality. From this data population prevalence estimates were determined for respiratory acidosis, from which the need for NIV in a typical district general hospital was modelled. RESULTS: 983 patients were admitted, 11 of whom required immediate intubation. 20% of the remaining 972 had a respiratory acidosis. Acidosis was associated with subsequent admission to the intensive care unit (ICU): pH<7.25, OR 6.10 (95% confidence interval (CI) 1.19 to 31.11); pH 7.25-7.30, OR 8.73 (95% CI 2.11 to 36.06). pH was inversely correlated with arterial oxygen tension (PaO(2)) in the 47% of patients who were hypercapnic, with a PaO(2) of >10 kPa being associated with acidosis in most hypercapnic patients. 80% remained acidotic after initial treatment, giving an age/sex specific prevalence for England and Wales of 75 (95% CI 61 to 90)/100 000/year for men aged 45-79 years and 57 (95% CI 46 to 69)/100 000/year for women. Modelling the need for NIV for all COPD patients indicates that a typical UK hospital will admit 90 patients per year with acidosis of which 72 will require NIV. CONCLUSIONS: In patients with acute COPD the PaO(2) should be maintained at 7.3-10 kPa (SaO(2) 85-92%) to avoid the dangers of hypoxia and acidosis. If all COPD patients with a respiratory acidosis (pH<7.35) after initial treatment are offered NIV, a typical UK hospital will treat 72 patients per year.

Chronic metabolic alkalosis: not uncommon in young children with severe cystic fibrosis.

The acid-base balance of 199 patients with cystic fibrosis, seen from 1987 through 1992 at the Bern Outpatient Clinic, were evaluated. Simple metabolic alkalosis was demonstrated in 16 and mixed metabolic alkalosis and respiratory acidosis in 9 patients. When compared with 10 patients with simple respiratory acidosis and 16 with normal hydrogen ion balance, those with simple metabolic alkalosis were significantly younger. The need for pancreatic enzymes was significantly higher and the relative underweight significantly more severe in patients with either simple or mixed metabolic alkalosis and respiratory acidosis. The results indicate the rather common occurrence of chronic metabolic alkalosis in cystic fibrosis. It is observed in young patients, in patients who need high doses of pancreatic enzymes and in the those with poor nutritional status.

The pattern of breathing during successful and unsuccessful trials of weaning from mechanical ventilation.

We prospectively examined the pattern of breathing in patients being weaned from mechanical ventilation: one group (n = 10) underwent a successful weaning trial and were extubated, whereas another group (n = 7) developed respiratory failure and required the reinstitution of mechanical ventilation. During the period of ventilator support, minute ventilation (VI), tidal volume (VT), and respiratory frequency (f) were similar in the 2 groups. After discontinuation of the ventilator, VI remained similar in the 2 groups, but VT was lower and f was higher in the patients who failed the trial compared with those who were successful, 194 +/- 23 and 398 +/- 56 ml (p less than 0.001), respectively, and 32.3 +/- 2.3 and 20.9 +/- 2.8 breaths/min (p less than 0.001), respectively. The failure group displayed a significant increase in PaCO2 (p less than 0.005) during spontaneous breathing, without a concomitant increase in the alveolar-arterial PO2 difference. Eighty-one percent of the variance in PaCO2 was accounted for by the pattern of rapid, shallow breathing. During weaning, resting respiratory drive (reflected by mean inspiratory flow, VT/TI) and fractional inspiratory time (TI/Ttot) were similar in the 2 groups. The patients in the failure group showed significant increases in VT/TI, 265 +/- 27 to 328 +/- 32 ml/s (p less than 0.01), and VI, 5.82 +/- 0.53 to 7.32 +/- 0.52 L/min (p less than 0.01), from the beginning to the end of the weaning trial; VT and f showed no further change.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence of metabolic alkalemia in hospitalized patients.

Analysis of 13,430 arterial blood samples demonstrated that metabolic alkalemia was the most common acid-base disturbance encountered in the hospital setting, being present in 51% of patients with abnormal acid-base status. Respiratory alkalemia was encountered in 29%, respiratory acidemia in 27%, and metabolic acidemia in only 12%. Evaluation of those blood gases with metabolic alkalemia, using 95% confidence-limit bands for acid-base disturbances, showed that the metabolic alkalemia was pure in 70% of the cases, mixed with respiratory acidemia in 18%, and combined with respiratory alkalemia in 12%. The adverse effects of alkalemia may be subtle but often significant. Alveolar hypoventilation in response to metabolic alkalemia, without evidence of primary respiratory disease, was more frequent than is generally suspected. This hypoventilation often directly results in hypoxemia, as well as atelectasis with worsened ventilation/perfusion match-up. Alkalemia shifts the oxyhemoglobin dissociation curve to the left, increasing hemoglobin's affinity for oxygen, thus, limiting oxygen release at the tissue level. The presence of metabolic alkalemia makes it more difficult to wean patients from assisted ventilation. A clearer understanding of the frequency and significance of metabolic alkalemia should lead to more appropriate therapy to prevent or correct this acid-base disturbance and should result in a decreased morbidity and mortality in critically ill patients.