Venous Blood Gas Research Articles

A Case Report of Isovaleric Acidemia without Acidosis

The deficiency of isovaleryl-CoA dehydrogenase leads to an inborn recessive error of leucine metabolism named isovaleric acidemia (IVA). Its presentation may be either in the neonatal period as an acute episode of metabolic acidosis or later as a “chronic intermittent form.” Normal development is promoted by early diagnosis and treatment with a protein-restricted diet and supplementation with carnitine and glycine. The present case was a 35-day-old boy admitted with seizures, whose initial screening test was in favor of organic acidemia of the isovaleric acidemia type (Ammonia: 200 μmol/L). As the venous blood gas (VBG) analysis revealed no acidosis, newborn metabolic screening was repeated. Typical laboratory findings and elevated levels of C5 and C5/C2 confirmed isovaleric acidemia again. As the above patient had no acidosis while the other tests, including laboratory and genetic analysis, were in favor of IVA, he was considered to be a rare case.

METABOLIC ALKALEMIA IN HYPERCALCIURIA STONE FORMERS: DOES IT MATTER?

We collected clinical, demographic characteristics, and laboratory data from electronical medical charts of outpatients with calcium-kidney stones followed in our institution from January 2013 to July 2021. We diagnosed as metabolic alkalemia those cases in which the venous blood gas tests showed pH≥7.46 and bicarbonate concentration>26 mEq/L. Then, we applied statistical analysis to compare distinct categories between patients with and without metabolic alkalemia. We diagnosed metabolic alkalemia in 4.3% of hypercalciuric nephrolithiasis outpatients, and we verified that thiazides had been used in all of them except in one case. Furthermore, we observed that the amount of thiazide taken daily was higher in patients with metabolic alkalemia than those without this imbalance. Additionally, hypokalemia was present in 37% of patients that developed metabolic alkalemia. We also found lower chloride, magnesium and ionic calcium serum concentrations in patients with metabolic alkalemia than in those without an acid-base disequilibrium. Despite the low prevalence of metabolic alkalemia in hypercalciuric kidney stone formers, it is important to monitor these patients due to high incidence of hypokalemia and the potential presence of other electrolyte disorders.

7761 Unmasking The Uncommon: A Case Of Primary Adrenal Insufficiency Presenting As Severe Hypercalcemia

Abstract Disclosure: A. Misbah: None. Z. Al-Hiti: None. A. Saleh: None. M. Joda: None. K. Rajamani: None. Adrenal insufficiency is a recognized but uncommon cause of hypercalcemia. The exact mechanism remains unknown; however, it is thought to be a combination of the hypovolemic state in adrenal insufficiency leading to decreased urinary clearance, as well as increased bone resorption. We present a case of primary adrenal insufficiency presenting with severe hypercalcemia. A 41 year old female with a past medical history of osteopenia, recently diagnosed postural orthostatic tachycardia syndrome (POTS), and hyponatremia attributed to SIADH presented with complaints of weakness and poor oral intake. She also reported a history of nausea, vomiting, weight loss, fatigue, and dizziness, for the last few months. She reported feeling well prior to a COVID-19 infection a few months back. At presentation, she was hypotensive with a blood pressure of 70/50 mmHg, while her other vital signs were stable. She appeared ill, and was noted to have dry oral mucous membranes. There was no increased pigmentation noted on exam. Initial laboratory evaluation revealed sodium of 130 (135-145 mmol/L), potassium of 5.3 (3.5-5.1 mmol/L), and creatinine of 1.7 (0.5-0.8 mg/dL). She had severe hypercalcemia with a calcium level of 15.5 (8.3-10.6 mg/dL) and had a blood glucose level of 53 (70-100 mg/dL). Venous blood gas indicated metabolic acidosis. Morning cortisol was low at 1 (3-23 ug/dL). Serum ACTH was elevated at 775 (0-46 pg/mL). Cosyntropin stimulation test confirmed primary adrenal insufficiency. She underwent work-up for hypercalcemia, which revealed a suppressed PTH, normal levels of PTHrP, vitamin D, and vitamin A. Serum and urine protein electrophoresis was normal. She was initially managed in the ICU and received aggressive fluid resuscitation. She was started on stress dose of hydrocortisone, which was then tapered to physiological doses of oral hydrocortisone and fludrocortisone. Subsequent improvements were observed in blood pressure, laboratory abnormalities, and normalized serum calcium levels. She was discharged home on hydrocortisone and fludrocortisone. On follow-up, she was doing well with the resolution of her symptoms. This case highlights the importance of recognizing adrenal insufficiency as one of the causes of hypercalcemia. Although hypercalcemia as a consequence of adrenal insufficiency is well-documented, the exact prevalence is not known but is estimated to be around 6%. After excluding more common diseases such as primary hyperparathyroidism and malignancy, the possibility of adrenal insufficiency should be considered as a cause of hypercalcemia. Treatment involves hormone replacement as well as hydration, bringing resolution to symptoms. Her presentation was unique, also due to the fact that her initial symptoms were diagnosed as POTS as well as SIADH. Given the onset of symptoms after a COVID-19 infection a few months ago, there could also be a potential link between the two. Presentation: 6/3/2024

8269 Euglycemic Diabetic Ketoacidosis Secondary to Rapid Weight Loss in a Patient on Dapagliflozin

Abstract Disclosure: A. Sridhar: None. A. Iqbal: None. A. Prabha Kumar: None. F. Haider: None. M. Babic: None. Background: Euglycemic DKA (eDKA) is a potentially life-threatening complication in patients taking SGLT 2 inhibitors (SGLT2i). Common precipitating factors include strenuous exercise, carbohydrate restriction, starvation, and alcohol use. Clinical case: The patient is a 71-year-old female with past medical history of Type 2 diabetes mellitus (DM), gastro-esophageal reflux disease, hypertension, hyperlipidemia, coronary artery disease and chronic pain syndrome. She presented with complaints of nausea, vomiting, reduced appetite and generalized weakness for the past 4 days. She also reported an intentional weight loss of 35 pounds in the last 6 weeks achieved with daily exercise and a carbohydrate restricted diet. She had been taking Dapagliflozin-Metformin 5-1000 mg twice daily and pioglitazone 30 mg once daily for 2 years and Ozempic subcutaneous injection 1 mg weekly for 6 months. Physical examination in the ED showed normal vital signs, dry mucous membranes, and trace bilateral lower extremity edema. Blood work was significant for venous blood gas pH 7.24, bicarbonate 9 mmol/L, anion gap 30 mmol/L, blood glucose 94 mg/dL, HbA1c 5.8 % and WBC 13.2 K/uL. Urinalysis was positive for glucose and ketones. The patient was admitted for management of eDKA and was started on intravenous 10% dextrose infusion and insulin infusion. Endocrinology was consulted and they recommended following DKA protocol and stopping Dapagliflozin at discharge. She was maintained on insulin infusion for 48 hours after which her anion gap normalized, and she was transitioned to subcutaneous insulin with Lantus 8 units and sliding scale insulin. During this time the patient’s symptoms resolved, and she was able to tolerate oral diet. She eventually resumed her home medications with oral Metformin 1000 mg twice daily and pioglitazone 30 mg once daily. Dapagliflozin and Ozempic were discontinued at discharge. Strenuous exercise and carbohydrate restriction which caused rapid weight loss, were likely the triggers for eDKA in our patient. A diabetes educator was involved at discharge and the patient was counseled to avoid possible triggers and identify warning signs and symptoms in the future. The patient was discharged with a follow up appointment with her Endocrinologist. Conclusion: High index of clinical suspicion is important to promptly diagnose eDKA in patients taking SGLT2i. Patient education on avoiding precipitating factors and early recognition of signs and symptoms is necessary to reduce mortality. Presentation: 6/3/2024

8472 A Little Too Much Of Tums: A Unique Presentation Of Milk Alkali Syndrome

Abstract Disclosure: Z. Al-Hiti: None. A. Misbah: None. Milk-Alkali Syndrome is characterized by a triad of hypercalcemia, metabolic alkalosis, and renal dysfunction. Historically associated with the excessive consumption of milk and alkali-containing antacids, it has re-emerged in recent years due to the widespread use of calcium and vitamin D supplements. It primarily results from an imbalance between calcium intake and renal excretion, leading to elevated calcium levels in the bloodstream. We present a case of milk-alkali syndrome with persistent renal dysfunction after normalizing calcium levels. We present the case of a 65-year-old male who presented to the emergency department with generalized weakness, poor oral intake, and confusion for 3 days. He was noted to have been more adherent with taking his prescribed medications over the last 2 weeks, which include calcitriol 0.5 mcg BID, calcium acetate 667 mg TID, and calcium carbonate 800 mg TID. On admission, he was afebrile and hemodynamically stable. . On examination, he had dry mucous membranes. He had no focal neurological deficits but he was confused and lethargic, and was only oriented to self. Other examination was noncontributory. Complete blood count and urinalysis were largely unremarkable. Chemistry demonstrated an elevated calcium level of 16.0 (8.3-10.6 mg/dL), ionized calcium of 7.3 (4.6-5.3 mg/dL), sodium of 134 (135-145 mmol/L), potassium of 5.4 (3.5-5.1 mmol/L), high phosphorus of 5.3 (2.4-5.1 mg/dL), and bicarbonate of 36 (20-31 mEq/L). Creatinine was elevated at 2.9 (0.6-1.1 mg/dL) from baseline of 1.3 to 1.4 mg/dL, and he had a BUN of 40(9-23 mg/dL). Venous blood gas showed a pH of 7.54( 7.32-7.42), pCO2 of 56 (40-52 mm Hg), and bicarbonate of 38 (23-28 mEq/L), indicating metabolic alkalosis. TSH was elevated at 36.15 (0.55- 4.78 uIU/mL) with a level of 140 two weeks back. Chest X-ray, renal ultrasound and CT head all showed no acute disease. Further work-up revealed a low PTH level of 6.3 (18.4-80 pg/mL), normal PTHrP level and 25-OH Vitamin D. There was no monoclonal gammopathy. Management included aggressive IV fluid resuscitation and IV calcitonin. However, no zoledronic acid was given due to a history of parathyroidectomy and risk of hypocalcemia. His serum calcium improved and eventually normalized. His confusion resolved. However, his creatinine and BUN increased to 3.4 mg/dL and 77, respectively, and did not improve to his baseline. This case highlights the importance of recognizing Milk-Alkali Syndrome as a potential consequence of over-the-counter calcium supplementation and highlights the potential for acute kidney injury which could be irreversible. Healthcare providers should be vigilant in identifying patients at risk, which includes older patients and patients with chronic kidney disease. Early recognition and appropriate management are crucial to prevent further renal deterioration and improve outcomes in individuals with Milk-Alkali Syndrome. Presentation: 6/2/2024

12431 14-year-old Presenting With Thrombocytopenia-Associated Multi-Organ Failure In The Setting Of Diabetic Ketoacidosis/Hyperosmolar Hyperglycemic Syndrome

Abstract Disclosure: N.C. Gunaratne-Breaux: None. D. Deplewski: None. Title: 14-Year-Old Presenting with Thrombocytopenia Associated Multi-Organ Failure in the setting of Diabetic Ketoacidosis/Hyperosmolar Hyperglycemic Syndrome Background: Coagulation complications are rare in hyperglycemia emergencies in children and adolescents. In patients presenting with severe and atypical hyperglycemia emergencies, special considerations need to be made to rule out life-threatening coagulopathy. Clinical Case: A 14-year-old male with history of Type 1 Diabetes presented in severe Diabetic Ketoacidosis/Hyperosmolar Hyperglycemic Syndrome overlap. Initially had severe hypotension and altered mental status concerning for cerebral edema. Initial venous blood gas showed pH of 6.82, pCO2 17.1, and HCO3 2.8, serum glucose was 1375 mg/dL, serum ketones >7.00 mmol/L, and serum osmolality was 384 mOsm/kg. Once insulin drip was started, glucose, ketones, and serum osmolality improved, but patient continued to be encephalopathic and had worsening tachypnea and desaturations. Patient was eventually intubated. After intubation, patient’s acidosis improved, but patient developed kidney failure (prompting initiation of dialysis), liver injury, decreased cardiac function, and high inflammatory state. A comprehensive multi-specialty team including pediatric intensive care, infectious diseases, rheumatology, neurology, and cardiology were involved in the care. On day three of admission, patient had multiple areas of ischemia on fingertips and ear and clotting of multiple IV and dialysis catheters, prompting a coagulopathy evaluation. Labs showed microcytic anemia (hemoglobin 10.0 g/dL; mean corpuscular volume 75fL), thrombocytopenia (platelet count 17 10e3/uL), coagulopathy (prothrombin time 16.8 sec, INR 1.3, prolonged thrombin time 48.8 sec), and elevated ferritin (507 ng/mL). Given labs and multi-organ involvement, determined by hematology to be Thrombocytopenia Associated Multi-Organ Failure (TAMOF). Patient was started on plasmapheresis and had dramatic improvement – was eventually extubated and returned to neurologic baseline without any notable deficits. Multi-specialty team ruled out all other possible causes of TAMOF; determination that the TAMOF developed secondary to DKA/HHS. Conclusion: Hyperglycemia emergencies can lead to a hyperinflammatory state that can lead to disruption of the coagulation cascade, including disseminated intravascular coagulopathy or thrombotic thrombocytopenia purpura. There have been rare reports of thrombocytopenia associated multi-organ failure provoked by DKA, thought secondary to critical illness mediated low ADAMST13 levels. This is a novel case of TAMOF caused by DKA/HHS overlap syndrome. It is important to screen for coagulopathy in cases of patients with DKA or DKA/HHS who do not show clinical improvement with resolution of ketosis and hyperosmolarity. Presentation: 6/2/2024

5147 Use of hypertonic saline in severe symptomatic hyponatraemia; results from a national survey from United Kingdom

Abstract Disclosure: M. Arshad: None. A. Iqbal: None. Background: Acute severe symptomatic hyponatraemia is potentially life-threatening. Irrespective of the underlying aetiology, hypertonic saline (HTS) is effective at rapidly correcting serum sodium. Several clinical treatment guidelines have aimed to standardise the administration of HTS. The European Society of Endocrinology (ESE) guidelines (2014) recommend two boluses of 150 mL 3% HTS with an aim to raise serum sodium concentration by 5 mmol/L([1]). It is important to note that the evidence supporting this approach is limited, and concerns have been raised regarding the potential for overcorrection using this protocol(2). Aim: To assess the practices and perceptions surrounding hypertonic saline (HTS) use in severe symptomatic hyponatraemia among United Kingdom (UK) endocrinologists and specialty trainees (fellows). Methods: An anonymous online survey was disseminated to all clinical members of the Society for Endocrinology (UK) between 24/10/2023 and 30/11/2023 using Survey Monkey ®, a web-based multiple-choice questionnaire. Results: Of 133 respondents (60.1% consultants, 33.1% specialty trainees, 6.8% other), 85% employed bolus treatment with HTS only, with 9.8% using both bolus and continuous infusions. Most (50.4%) preferred 150 mL boluses, followed by 100 mL boluses (18.8%). Commonly used HTS strengths were 2.7% (45.1%), followed by 1.8% (31.6%), while the 3% HTS strength recommended by ESE guidance was used by 21.8%. Only 7 (5.3%) respondents used weight-based HTS dosage. Contrary to guidelines, 74.4% did not administer a second bolus without waiting for sodium result from the first bolus. Also, 86% have experience using venous blood gas sodium readings for monitoring, even though this has not been mentioned or recommended in the guidelines. HTS was always administered in high-dependency settings by 16.5% and mostly administered in this setting by 49.6%. Overcorrection targets defined by 10 and 8 mmol/24 hours cut-offs were used by 48.9% and 39.9%, respectively. For definite or expected overcorrection, 75.9% preferred 5% dextrose, while 40.6% had experience with desmopressin (DDAVP). Conclusion: Significant variation exists in HTS use for severe symptomatic hyponatraemia in the UK, deviating from guidelines, especially regarding a second bolus without assessing the first bolus's biochemical impact. European guidelines warrant an evidence-based revision to harmonize clinical practice.

Suggested guide to using lactate gap as a surrogate marker in the diagnosis of ethylene glycol overdose.

Ethylene glycol (EG) poisoning, if not diagnosed rapidly, can lead to poor patient outcomes. Gas Chromatography (GC) is primarily used for EG quantitation which is rarely available, and the turn-around time may be prolonged. Most lactate results from point-of care (POCT) methods are falsely elevated in EG poisoning compared with automated chemistry analyser results. In combination the lactate gap (POCT-Automated chemistry) can be used as surrogate marker in just about all laboratories to indicate likely EG toxicity and guide treatment. A male presented by ambulance to hospital with severe agitation requiring mechanical ventilation to facilitate ongoing management. Venous blood gas analysis confirmed a high anion gap metabolic acidosis (HAGMA) with an elevated lactate. The lactate and osmolarity measured in the laboratory showed a normal lactate and high osmolarity, giving a large osmolar gap. The patient was immediately commenced on renal replacement therapy for presumed EG poisoning to minimize kidney injury, and the treatment continued for 19 hours. A very high EG concentration was confirmed by GC the next day. An elevated lactate gap along with a HAGMA and osmolar gap can provide rapid surrogate laboratory data indicating EG poisoning enabling timely treatment and better patient outcomes.

A-333 Comparison between measured total carbon dioxide and calculated bicarbonate in hospitalized patients

Abstract Background Bicarbonate (HCO3-) is a key indicator of anion excess or deficit and important clinically for assessing acid-base balance. For patient care, HCO3- may be reported as a calculated value from blood gas analysis or measured on automated chemistry analyzers. When measured, the final result includes HCO3-, carbonate (CO32-) and carbamino compounds and thus is reported as total CO2 (TCO2). Anecdotally, some patients have discrepancies between HCO3- and TCO2. However, there is limited data in the published literature assessing agreement between the two methods. Our study aims to compare the calculated HCO3- values with measured TCO2 obtained from simultaneously collected clinical specimens. Methods This study included all results from physician ordered HCO3- and TCO2 between 01/2019 to 12/2020 retrospectively retrieved from the laboratory information system (Cerner). Specimens were collected by nursing staff within 5 minutes of each other. TCO2 was assessed on a Roche cobas 702 (CV = 4.2%) according to the manufacturer’s instructions using an enzymatic phosphoenolpyruvate carboxylase method in lithium heparin tubes. HCO3- was calculated using a Radiometer ABL800 blood gas analyzer from arterial or venous blood gas samples according to the manufacturer’s instructions. Briefly, HCO3- is calculated using the Henderson-hasselbalch equation and the measurement of PCO2 (CV= 1.75%), and pH (CV = 0.06%). Deming regression was performed. The CLIA total allowable error of 4 mmol/L and a reference change value (RCV, Cv Individual = 4%) of -13 and + 14 for TCO2 was used to assess agreement. All data was analyzed in R. Results There were 101,895 paired HCO3- and TCO2 results during the study period. The values ranged from 4 to 56 mmol/L and the mean was 25.7. The mean difference between the calculated HCO3- and measured TCO2 was 1.33 mmol/L. Relative to HCO3-, there were 2,119 (2.1%) TCO2 results with a negative bias exceeding 4 mmol/L and 427 (0.4%)[FC1] with a positive bias exceeding 4 mmol/L. Twenty-two samples exceeded the positive RCV of 14% and 22 samples exceeded the negative RCV. Deming regression revealed a slope of 1.09 (95% CI: 1.087-1.092) an intercept of -2.19 (-2.18 to -2.06), and a Pearson correlation of 0.960 (0.959 to 0.960). We also analyzed differences between HCO3- and TCO2 in arterial and venous samples. The Pearson r for venous samples was 0.956 (0.955 to 0.957) and for arterial samples was 0.966 (0.966-0.966). Deming regression revealed a slope of 1.099 (0.195 to 1.104) and 1.071 (1.068 to 1.074) for venous and arterial samples respectively. The intercept for venous samples was -1.441 (-1.559 to -1.324) and for arterial was -2.005 (-2.072 to -1.938). Conclusions There is bias between HCO3- calculations and TCO2 measurements in simultaneously drawn samples. A small proportion of samples (2.5%) exceed the CLIA total allowable error between the results but very few exceed the RCV. This may due to differences in matrices, with different correlations and slopes observed between arterial and venous specimens. Further studies are required to distinguish the causes of the observed differences between HCO3- and TCO2.

Pcv-aCO2/Ca-cvO2 Combined with Optic Nerve Sheath Diameter in Predicting Elevated Intracranial Pressure of Patients with Traumatic Brain Injury in Prehospital Setting.

To investigate a correlation between the central venous minus arterial CO2 pressure to arterial minus central venous O2 content ratio (Pcv-aCO2/Ca-cvO2) combined with optic nerve sheath diameter (ONSD) in predicting prehospital elevated intracranial pressure (ICP) in traumatic brain injury (TBI) patients. This was a prospective observational study of all adult TBI patients from the surgical intensive care unit who underwent invasive ICP monitoring between January 2023 and December 2023. Using a Delica MVU-6300 machine with 14-5 MHz linear probe to measure ONSD. We drew blood samples for arterial and central venous blood gases to measure and calculate the following indicators such as Pcv-aCO2, Ca-cvO2, and Pcv-aCO2/Ca-cvO2 ratio. ONSD and Pcv-aCO2/Ca-cvO2 were recorded during the first 3 days after admission. Simultaneous ICP values were gained from the invasive monitoring. Associations between ONSD, Pcv-aCO2/Ca-cvO2 and simultaneous ICP were explored by Spearman correlation analysis. We constructed an ROC curve to identify the ONSD and Pcv-aCO2/Ca-cvO2 cutoff for the evaluation of elevated ICP. We included 54 patients aged mean 57.13 (standard deviation 4.02) years and 24 (44%) were male. A significant correlation was observed between ONSD and ICP (r = 0.74, P < 0.01). The AUC was 0.861 (95% CI: 0.727-0.951), with a best cutoff value of 5.62 mm. Using a cutoff of 5.62mm, ONSD had a sensitivity of 92.8%, specificity of 80.4%. The Pcv-aCO2/Ca-cvO2 ratio also significantly correlated with ICP (r = 0.70, P < 0.01). The AUC was 0.791 (95% CI: 0.673-0.889). The optimal Pcv-aCO2/Ca-cvO2 value for predicting elevated ICP was 1.98mmHg/mL. Using a cutoff of 1.98mmHg/mL, Pcv-aCO2/Ca-cvO2 had a sensitivity of 87.3%, specificity of 77.2%. The AUC for ONSD combined with Pcv-aCO2/Ca-cvO2 was 0.952 (95% CI: 0.869-0.971), which had a sensitivity of 95.1%, specificity of 93.9%. Pcv-aCO2/Ca-cvO2 combined with ONSD performed best in predicting elevated intracranial pressure of patients with TBI in a prehospital setting. Our findings provide a crucial tool to improve earlier management of these patients in prehospital care, where the availability and utilization of invasive monitoring is limited. It could lead to significant changes in how TBI patients are monitored and treated before reaching a hospital.

Acid–base and electrolyte changes in dogs after packed red blood cell transfusion

AbstractBackgroundPacked RBC (pRBC) transfusions are often necessary to enhance organ perfusion and tissue oxygenation in cases of severe anemia.ObjectivesWe aimed to describe changes in acid–base and biochemical parameters in dogs after transfusion of pRBC and potential effects on the outcome.MethodsThe prospective observational study included anemic dogs requiring pRBC transfusions. Venous blood gas and electrolytes were measured pre‐transfusion and repeated within 1 h post‐transfusion. Signalment, pre‐existing conditions and underlying disease(s), number of days spent of hospitalization, the quantity of transfused pRBC units, and the outcome were also recorded. Associations between analytical values and all other parameters before and after transfusion were assessed using the Wilcoxon test. A generalized linear model was generated for each of the blood gas parameters post‐transfusion, including the pre‐transfusion values and the characteristics of the animal as fixed effects. The effect of the blood gas parameters on the mortality and hospitalization length was assessed using logistic regression and generalized linear models, respectively.ResultsTwenty‐six dogs with different causes of anemia were included in the study, with dogs remaining hospitalized for a median of 3 days (range: 0–11). Pre‐transfusion heart rate, respiratory rate, Angap, base excess, and lactate were higher than post‐transfusion values. Post‐transfusion results showed an increase in hematocrit, hemoglobin, HCO3‐, PCO2, tCO2, and chloride. Pre‐transfusion hypophosphatemia and receiving an increased volume of transfused pRBC were associated with a longer hospital stay, while higher pre‐transfusion lactate values were associated with higher mortality.ConclusionspRBC transfusion in anemic dogs was associated with an improvement in perfusion and acid–base parameters. Pre‐transfusion lactate may be an indicator of mortality in dogs.

Effects of Dexmedetomidine in Improving Oxygenation and Reducing Pulmonary Shunt in High-Risk Pediatric Patients Undergoing One-Lung Ventilation for Thoracic Surgery: A Double-Blind Randomized Controlled Trial.

Background and objectives Pediatric thoracic surgery has unique considerations due to the immaturity of the respiratory system anatomically and physiologically, which presents technical and pharmacological considerations, including the very common technique of one-lung ventilation (OLV), which causes serious complications in children. Therefore, we investigated the effects of dexmedetomidine on oxygenation and pulmonary shunt fraction (Qs/Qt) in high-risk pediatric patients undergoing OLV for thoracic surgery. This randomized controlled trial aimed to investigate dexmedetomidine's effect on the partial pressure of arterial oxygen (PaO2) and pulmonary shunt fraction (Qs/Qt). Methods A total of 63 children underwent thoracic surgery with OLV and were divided into two groups. The dexmedetomidine group (group Dex, n = 32) received dexmedetomidine (0.4 μg/kg/hour), and the placebo group (group placebo, n = 31) received normal saline. Two arterial and central venous blood samples were taken for arterial and venous blood gas analysis at four time points: T1 (10 minutes after mechanical ventilation of total lung ventilation), T2 (10 minutes after OLV), T3 (60 minutes after OLV), and T4 (20 minutes after the end of OLV). At these intervals, the following parameters were measured: PaO2, Qs/Qt, mean arterial pressure (MAP), heart rate (HR), and peak inspiratory pressure (PIP). Results The two groups had no significant differences in FEV1/FVC and baseline pulmonary shunt fraction (Qs/Qt). Dexmedetomidine significantly improved PaO2 compared with placebo during OLV (T2 and T3). There was a significant decrease in Qs/Qt compared with placebo during OLV (T2, T3, and T4). There was a decrease in PIP compared with placebo during OLV (T2 and T3). No statistically significant differences in MAP or HR were observed between the groups. Conclusion Infusion of dexmedetomidine during OLV in high-risk pediatric thoracic surgery reduces shunt and pulmonary shunt fraction Qs/Qt, improves PaO2 and body oxygenation, reduces PIP and pressure load, and maintains hemodynamic stability (MAP, HR).

Evaluating the Physiologic Effects of Alfaxalone, Dexmedetomidine, and Midazolam Combinations in Common Blue-Tongued Skinks (Tiliqua scincoides).

Common blue-tongued skinks (Tiliqua scincoides) are popular pet reptiles; however, there has been limited research to investigate sedatives for this species. The purpose of this study was to measure the physiologic effects of four combinations of alfaxalone, dexmedetomidine, and midazolam for minor procedures such as intubation and blood collection. Eleven common blue-tongued skinks (Tiliqua scincoides) were used for this prospective, randomized cross-over study. The subcutaneous combinations were used as follows: 20 mg/kg alfaxalone (A); 10 mg/kg alfaxalone and 1 mg/kg midazolam (AM); 0.1 mg/kg dexmedetomidine and 1 mg/kg midazolam (DM); and 5 mg/kg alfaxalone, 0.05 mg/kg dexmedetomidine, and 0.5 mg/kg midazolam (ADM). Heart rate, respiratory rate, palpebral reflex, righting reflex, escape reflex, toe pinch withdrawal reflex, tongue flicking, and the possibility of intubation were recorded at baseline and every 5 min for 60 min. Venous blood gases were measured at baseline, full sedation, and recovery. Heart and respiratory rates decreased significantly in all groups, but the reductions were most prominent in DM and ADM. Analgesic effects, as measured by the toe pinch withdrawal reflex, were only observed in DM and ADM. Intubation was possible in all four protocols; however, it was not possible in two DM skinks. Based on these trials, ADM and AM are recommended for minor procedures in blue-tongue skinks.

Repercussions of SARS-CoV-2 infection on intrapulmonary shunt in patients undergoing one-lung ventilation

BackgroundHypoxic pulmonary vasoconstriction is the most important regulatory mechanism by which right-to-left shunts decrease during one-lung ventilation (OLV), but the effects of pulmonary microarterial thrombosis and impaired HPV after SARS-CoV-2 infection on intrapulmonary shunt during OLV remain unknown. The aim of this study was to observe the changes of intrapulmonary shunt in patients undergoing thoracoscopic partial pneumonectomy at different periods after SARS-CoV-2 infection compared with patients without SARS-CoV-2 infection history.MethodsA total of 80 patients who underwent elective thoracoscopic partial lung resection and were classified as American Society of Anaesthesiologists (ASA) grades I-II were selected and divided into 4 groups (n = 20 in each group): patients not infected with SARS-CoV-2 (Group A), patients infected with SARS-CoV-2 for 5–8 weeks (Group B), patients infected with SARS-CoV-2 for 9–12 weeks (Group C), and patients infected with SARS-CoV-2 for 13–16 weeks (Group D). For all patients, the same anaesthesia method was adopted, and anaesthesia was maintained with propofol, remifentanil, and cisatracurium. Radial artery and mixed venous blood gases were measured at 10 min of two-lung ventilation (TLV), 15 min of one-lung ventilation (OLV15), and 30 min of OLV (OLV30) in the lateral recumbent position to calculate the intrapulmonary shunt. Multiple linear regression analysis was employed to investigate the association between intrapulmonary shunt and SARS-CoV-2 infection.ResultsQs/Qt at TLV was significantly higher in Groups B and C than in Group A (P < 0.05), and PaO2 at TLV was significantly lower in Groups B and C than in Group A (P < 0.05). Qs/Qt values at OLV15 and OLV30 were significantly higher in Group B, C or D than in Group A (P < 0.05), and PaO2 values at OLV15 and OLV30 were significantly lower in Groups B, C or D than in Group A (P < 0.05). Multiple linear regression analysis revealed that SARS-CoV-2 infection (95%CI -4.245 to -0.679, P = 0.007) was an independent risk factor for increased intrapulmonary shunt during TLV, while SARS-CoV-2 infection (95%CI 0.124 to 3.661, P = 0.036), exacerbation of COVID-19 clinical classification (95%CI -5.203 to -1.139, P = 0.003), and persistent symptoms (95%CI -12.122 to -5.522, P < 0.001) were independent risk factors for increased intrapulmonary shunt during OLV after SARS-CoV-2 infection.ConclusionSARS-CoV-2 infection increased intrapulmonary shunt and reduced oxygenation. Although oxygenation improved at TLV after 13–16 weeks of infection, intrapulmonary shunt and oxygenation under OLV took longer to recover.Trial registrationChinese Clinical Trial Registry, Retrospectively registered, Full date of first registration: 17/05/2023, Registration number: ChiCTR2300071539.

Can end-tidal CO2 measurement replace arterial partial CO2 in emergency department respiratory distress management?

ObjectiveTo assess the feasibility of using end-tidal carbon dioxide (EtCO2) as a non-invasive substitute for partial pressure of arterial carbon dioxide (PaCO2) in emergency department (ED) triage and follow-up, and to explore the potential of partial pressure of venous carbon dioxide (PvCO2) as an alternative to PaCO2. DesignProspective cross-sectional study. SettingTertiary university hospital. Patients or participants97 patients presenting with acute respiratory distress to the ED. InterventionsEtCO2, arterial blood gases, and venous blood gases measured at admission (0 min), 60 min, and 120 min. Main variables of interestCO2 levels. ResultsAmong 97 patients (mean age: 70.93 ± 9.6 years; 60.8% male), EtCO2 > 45 mmHg at admission showed strong positive correlations with PaCO2 and PvCO2 (r = 0.844, r = 0.803; p < 0.001, respectively). Significant positive correlation was observed between 60-min EtCO2 and PaCO2 (r = 0.729; p < 0.001). Strong correlation between PaCO2 and PvCO2 at 120 min when EtCO2 > 45 mmHg (r = 0.870; p < 0.001). EtCO2 was higher in hospitalized patients compared to discharged ones. ConclusionsEtCO2 appears promising as a substitute for PaCO2 in ED patients with acute respiratory distress within the initial two hours of treatment. Venous blood gas sampling offers a less invasive alternative to arterial sampling, facilitating simultaneous blood tests.

Effect of Deep Hypothermia (18°C) on Dioxygen Metabolism During Pulmonary Thromboendarterectomy Surgery

Objectives: The aim of this physiological pilot study was to investigate the effect of deep hypothermia on oxygen extraction (OE) and consumption (VO2) in normothermic conditions (36-37°C) then at different stages of cooling: 30°C, 25°C and 18°C. Design: For three months, we conduct a prospective study on patients that underwent pulmonary thromboendarterectomy. Settings: This is a single center study done in a university teaching hospital. ParticipantsPatients that underwent pulmonary thromboendarterectomy during the inclusion period. InterventionsHemodynamic and biological data were recorded from arterial and venous blood gas samples withdrawn first at normothermia, then at 30°C, 25°C and 18°C.. Measurements and Main Results24 patients were included in the final analysis. Indexed VO2 decreased from 65.9 ml to 25.1 ml of O2/min/m2 between 36°C and 18°C (p<0.001). The OE decreased from 18% to 9% between 36°C and 18°C (p<0.001). At normal temperature and at 18°C, the median venoarterial difference of O2 bound to hemoglobin was 2.22 [1.68-2.58] and 0.03 [0.01-0.07] ml of O2/100 ml of blood, respectively (p<0.001). Whereas the median venoarterial difference of dissolved O2 was 0.78 [0.66-0.92] and 1.09 [1.03-1.32] ml of O2/100 ml of blood, respectively (p=0.0013). Conclusion: There is a VO2 and OE decrease of more than half of their baseline value at 18°C. Seeing that the metabolic needs are essentially supplied from dissolved O2 during cooling from 30°C to 18°C, we suggest that PaO2 should be increased during the period of cooling and/or of deep hypothermia to prevent hypoxia.

Evaluation of the Effect of N95/ffp2 Masks on Venous Blood Gas and Clinical Symptoms in Medical Personnel in Work Shifts

Evaluation of the Effect of N95/ffp2 Masks on Venous Blood Gas and Clinical Symptoms in Medical Personnel in Work Shifts

Correlation of arterial and venous blood gas analysis in respiratory failure in children

IntroductionArterial and venous blood gases provide similar and very close measurements in terms of PH, pCO2, HCO3, pO2 levels. The study aims to investigate correlation of arterial and venous blood gas analysis in respiratory failure caused by pneumonia in children.MethodsThis cross-sectional study employed a consecutive sampling method from pediatric patients experiencing respiratory failure. Point of Care (POCT) was used to examine blood gas analysis.ResultThere was no significant difference between pH artery and venous with p = 0,232 (95% confidence interval [CI]: -14.628-59,488). The Mean difference between arterial and venous pH was 0,22 with a strong Spearman correlation of 0,643 (p < 0,001). There was a significant difference between arterial and venous pCO2 with p = 0,022 (95% confidence interval [CI]: -8,7- (− 0,69)). The mean difference between arterial and venous pCO2 was 4,69 with a moderate Spearman correlation of 0,485 (p < 0,001). There was no significant difference between arterial and venous HCO3 with p = 0,38. The Mean difference between arterial and venous HCO3 was 3,1 with a very strong Spearman correlation of 0,848 (p < 0,001). There was a very significant difference between arterial and venous pO2 with p < 0,001. The Mean difference between arterial and venous pO2 was 27,4 with a weak Spearman correlation of 0,17 (p = 0,117).ConclusionThere was strong correlation between arterial and venous pH, a moderate correlation between arterial and venous pCO2, a very strong correlation between arterial and venous HCO3 and a very weak correlation between arterial and venous pO2 using POCT.

The use of venous blood gas in assessing arterial acid−base and oxygenation status – an analysis of aggregated data from multiple studies evaluating the venous to arterial conversion (v-TAC) method

ABSTRACT Background Several methods exist to reduce the number of arterial blood gases (ABGs). One method, Roche v-TAC, has been evaluated in different patient groups. This paper aggregates data from these studies, in different patient categories using common analysis criteria. Research design and methods We included studies evaluating v-TAC based on paired arterial and peripheral venous blood samples. Bland-Altman analysis compared measured and calculated arterial values of pH, PCO2, and PO2. Subgroup analyses were performed for normal, chronic hypercapnia and chronic base excess, acute hyper- and hypocapnia, and acute and chronic base deficits. Results 811 samples from 12 studies were included. Bias and limits of agreement for measured and calculated values: pH 0.001 (−0.029 to 0.031), PCO2 −0.08 (−0.65 to 0.49) kPa, and PO2 0.04 (−1.71 to 1.78) kPa, with similar values for all sub-group analyses. Conclusion These data suggest that v-TAC analysis may have a role in replacing ABGs, avoiding arterial puncture. Substantial data exist in patients with chronic hypercapnia and chronic base excess, acute hyper- and hypocapnia, and in patients with relatively normal acid−base status, with similar bias and precision across groups and across study data. Limited data exist for patients with acute and chronic base deficits.

Association of Serum Lactate Levels Measured in the Emergency Department with 30-Day Mortality in Older Patients with Unilateral Hip Fractures.

Hip fractures are frequent injuries in older patients and are associated with high mortality rates. This study assessed the association between serum lactate level and 30-day mortality in older patients with unilateral hip fractures and examined the prognostic value of this association on the clinical outcomes of these patients. This retrospective, single-center study included patients aged ≥65 years admitted to the emergency department due to low-energy trauma and diagnosed with unilateral hip fracture upon admission. The additional inclusion criteria were patients with independent ambulation or walker or cane assistance before the injury, with available data on serum lactate levels on venous blood gas analysis, and who underwent surgery. Among the 330 included patients, 30.9% experienced postoperative complications and 10.3% died within 30 days. Using a lactate cut-off value of 2 mmol/L to distinguish between living and deceased patients, the sensitivity and specificity were 41% and 88%, respectively. Multivariate logistic regression analysis revealed that high lactate and low albumin levels and male sex were associated with mortality. Identifying risk factors for mortality in geriatric patients with hip fractures is important. Male sex, low albumin levels, and particularly increased lactate levels were independent predictors of short-term mortality in these patients.