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.

Spontaneous Hyperventilation in Severe Traumatic Brain Injury: Incidence and Association with Poor Neurological Outcome.

BACKGROUND: Hypocapnia induces cerebral vasoconstriction leading to a decrease in cerebral blood flow, which might precipitate cerebral ischemia. Hypocapnia can be intentional to treat intracranial hypertension or unintentional due to a spontaneous hyperventilation (SHV). SHV is frequent after subarachnoid hemorrhage. However, it is understudied in patients with severe traumatic brain injury (TBI). The objective of this study was to describe the incidence and consequences on outcome of SHV after severe TBI. METHODS: We conducted a retrospective, observational study including all intubated TBI patients admitted in the trauma center and still comatose 24 h after the withdrawal of sedation. SHV was defined by the presence of at least one arterial blood gas (ABG) with both PaCO2 < 35 mmHg and pH > 7.45. Patient characteristics and outcome were extracted from a prospective registry of all intubated TBI admitted in the intensive care unit. ABG results were retrieved from patient files. A multivariable logistic regression model was developed to determine factors independently associated with unfavorable outcome (defined as a Glasgow Outcome Scale between 1 and 3) at 6-month follow-up. RESULTS: During 7 years, 110 patients fully respecting inclusion criteria were included. The overall incidence of SHV was 69.1% (95% CI [59.9-77]). Patients with SHV were more severely injured (median head AIS score (5 [4-5] vs. 4 [4-5]; p = 0.016)) and exhibited an elevated morbidity during their stay. The proportion of patients with an unfavorable functional neurologic outcome was significantly higher in patients with SHV: 40 (52.6%) versus 6 (17.6%), p = 0.0006. After adjusting for confounders, SHV remains an independent factor associated with unfavorable outcome at the 6-month follow-up (OR 4.1; 95% CI [1.2-14.4]). CONCLUSIONS: SHV is common in patients with a persistent coma after a severe TBI (overall rate: 69%) and was independently associated with unfavorable outcome at 6-month follow-up.

Desequilibrio ácido base en la unidad de cuidados intensivos / Acid basic disbalance in the intensive care unit

Este estudio se diseñó para determinar la frecuencia de las alteraciones ácido-base en una muestra de pacientes ingresados a una unidad de cuidados intensivos generales, mediante un estudio descriptivo y transversal. Se incluyeron 30 pacientes que ingresaron a la unidad de cuidados intensivos en quienes se revisó la determinación de gases arteriales y electrólitos séricos, así como la brecha aniónica. Mediante nomograma se identificaron los trastornos ácido-base mixtos. Los resultados mostraron, en todos los pacientes, desequilibrio ácido-base. El mayor porcentaje de casos fue en pacientes con alcalosis respiratoria crónica (46.6 por ciento), que invariablemente sucedió en quienes presentaban cardiopatía isquémica. La mortalidad fue mayor en pacientes con trastornos ácido-base mixtos

Alkalemia-associated morbidity and mortality in medical and surgical patients.

The difference in death rate among medical and surgical inpatients having alkalemia is incompletely defined. This prospective study was done to identify the incidence, mortality, and clinical factors that resulted in a poor outcome in both groups of patients. We screened a total of 10,811 consecutive arterial blood gas values; in 4,427 (40.9%) the pH was greater than 7.44, and in 2,577 (23.8%) the pH was greater than 7.48. The study group consisted of 409 patients (213 medical, 196 surgical) whose pH value was greater than 7.48; 253 of these patients (61.9%) had pure respiratory alkalosis, 120 (29.3%) had mixed respiratory and metabolic alkalosis, 27 (6.6%) had a mixed acid base disorder, and nine (2.2%) had pure metabolic alkalosis. Overall group mortality was 27.9% and increased as pH values rose, reaching 48.5% when the pH was greater than 7.60. The overall mortality among medical patients (36.6%) exceeded that among the surgical patients (12.4%) (P less than .05), an observation that applied over a wide range of pH values. Patients having mixed respiratory and metabolic alkalosis had a significantly poorer outcome (44.2% mortality) than the alkalemic group as a whole (27.9% mortality) (P less than .05). Alkalemia-associated illnesses are common in hospitalized patients and are associated with high mortality in both medical and surgical patients, though the death rate is higher among medical patients. Mixed respiratory and metabolic alkalosis appears to be associated with a particularly poor prognosis.

Chronic heat stress and respiratory alkalosis: occurrence and treatment in broiler chicks.

The occurrence of respiratory alkalosis and potential benefit derived from treatment were examined in thermostressed 4-week-old broiler chicks. Blood pH was greater (P less than .05) in heat-stressed (32 C) panting birds (7.395) than either nonpanting (7.28) or birds raised at 24 C (7.28). Acute thermostress, obtained by elevating ambient temperature from 32 to 41 C over a 20-min period further elevated (P less than .05) blood pH to 7.521. Chronic heat-stressed broiler chicks suffer from intermittent respiratory alkalosis during panting; with acute heat stress, chicks pant continuously and suffer from alkalosis. Including .5% sodium bicarbonate (NaHCO3) in the diet of birds subjected to chronic heat stress enhanced body weight gain by 9% even though it tended (P less than .10) to increase blood pH in nonpanting birds. Adding .3 or 1% ammonium chloride (NH4Cl) to diets decreased blood pH (P less than .01) to 7.194 and increased (P less than .05) body weight gains by 9.5 and 25%, respectively. Effects appeared linear with NH4Cl dose to 1% NH4Cl, but 3% NH4Cl elevated weight gains by only 8% and precipitated blood acidosis (pH 7.09) in nonpanting birds. Supplementing the 1% NH4Cl diet with .5% NaHCO3 increased weight gains an additional 9%. Manipulating sodium: chloride ratios by addition of calcium chloride increased body weight gain 8% and slightly reduced severity of alkalosis. Data indicate that blood alkalosis limits growth rate of broiler chicks reared under chronic thermostress and that the respiratory alkalosis and weight gain depressions attributed to thermostress can be partially alleviated dietarily.

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.