Arterial Blood pH Research Articles

Fetal “nonreassuring status” is associated with elevation of nucleated red blood cell counts and interleukin-6

Previous studies have established the association between fetal hypoxia and elevated nucleated red blood cells (NRBCs). Animal studies have demonstrated that a rise in plasma erythropoietin (EPO) is not detectable until 4 to 6 hours after the initiation of hypoxia. In contrast, interleukin-6 (IL-6) has the capacity to directly induce erythroid maturation. Therefore, we set forth to evaluate the role of EPO and IL-6 as potential mediators of elevated fetal NRBCs in response to acute hypoxia. Low-risk pregnancies with a normal fetal heart rate at admission to labor and delivery were eligible for participation. Deliveries for "nonreassuring fetal status" comprised the study group. All other deliveries served as controls. Umbilical cord blood was prospectively collected for blood gas analysis, NRBC counts, EPO, and IL-6. One hundred women participated in the study. Nonparametric univariate analysis demonstrated a significant association between elevated NRBC counts and Apgar scores, arterial cord blood pH, base excess, EPO, and IL-6 levels (all P values <.01). Stepwise regression analysis identified only pH, IL-6, and EPO as independent variables associated with elevated NRBC counts at birth (all P values <.0001 with R2 of 0.27, 0.42, and 0.46, respectively). A significant increase in NRBC counts was noted in study patients. IL-6 was significantly increased in study patients, whereas there was no difference in EPO between groups. The fact that NRBC counts were elevated in fetuses who were delivered for "nonreassuring fetal status" with EPO being normal and IL-6 being elevated implies that IL-6 may have a unique, short-term role in elevating fetal NRBC counts.

Long‐term effects of hypothermia on neuronal cell death and the concentration of apoptotic proteins after incomplete cerebral ischemia and reperfusion in rats

The present study investigates the long-term effects of postischemic hypothermia on neuronal cell damage and concentration changes of apoptotic proteins after cerebral ischemia. Sixty-four Sprague-Dawley rats were anesthetized, intubated and ventilated with 2.0 Vol% isoflurane and 70% N2O/O2. After preparation the animals were randomly assigned to the following groups: group 1 (n = 32, fentanyl-N2O/normothermia 37.5 degrees C), and group 2 (n = 32, fentanyl-N2O/hypothermia 34.0 degrees C. Ischemia (45 min) was induced by common carotid artery occlusion plus hemorrhagic hypotension (MAP = 40 mmHg). Arterial blood gases and pH were maintained constant. After 1, 3, 7, or 28 days (each n = 8) the brains were removed, frozen and cut. Neuronal damage was assessed by analyzing Bax, Bcl-2, p53, and Mdm-2 proteins, activated caspases-3-positive and eosinophilic cells. A third group (n = 8) of untreated animals served as naive controls. In hypothermic animals, Bax concentration was decreased by 50-70% over time compared to normothermia. On days 1 and 3, Bcl-2 was increased by 50% with hypothermia. The amount of activated caspase-3-positive cells in the ischemic hemisphere was 0.5% in the hypothermic and 1-2% in the normothermic animals. Of the hippocampal cells, 10-25% were eosinophilic in both groups over time. The present data show that hypothermia prevents an ischemia-induced increase of the pro-apoptotic protein Bax for as long as 28 days and increases the concentration of the antiapoptotic protein Bcl-2 up to 3 days compared to normothermic animals. Therefore, after cerebral ischemia, hypothermia has the sustained neuroprotective potential to shift apoptosis-related proteins towards neuronal cell survival.

Serum Potassium and Acid-base Parameters in Severe Dialysis-associated Hyperglycemia Treated with Insulin Therapy

We analyzed the changes in serum potassium concentration ([K]) and acid-base parameters in 43 episodes of dialysis-associated hyperglycemia (serum glucose level > 33.3 mmol/L), 22 of which were characterized as diabetic ketoacidosis (DKA) and the remaining 21 as nonketotic hyperglycemia (NKH). All episodes were treated with insulin therapy only. Age, gender, initial and final serum values of glucose, sodium, chloride, tonicity and osmolality did not differ between DKA and NKH. At presentation, serum values of [K] (DKA 6.2 +/- 1.3 mmol/L; NKH 5.2 +/- 1.5 mmol/L) and anion gap [AG] (DKA 27.2 +/- 6.4 mEq/L; NKH 15.4 +/- 3.5 mEq/L) were higher in DKA, whereas serum total carbon dioxide content [TCO2 ] (DKA 12.0 +/- 4.6 mmol/L; NKH 22.5 +/- 3.1 mmol/L), arterial blood pH (DKA 7.15 +/- 0.09; NKH 7.43 +/- 0.07) and arterial blood PaCO2 (DKA 26.2 +/- 12.3 mm Hg; NKH 34.5 +/- 6.7 mm Hg) were higher in NKH. At the end of insulin treatment, serum values of [K] (DKA 4.0 +/- 0.7 mmol/L, NKH 4.0 +/- 0.5 mmol/L), [AG] (DKA 16.3 +/- 5.4 mEq/L, NKH 14.9 +/- 3.0 mEq/L), [TCO2 ] (DKA 23.5 +/- 5.0 mmol/L, NKH 24.1 +/- 4.2 mmol/L), arterial blood pH (DKA 7.42 +/- 0.09, NKH 7.51 +/- 0.14) and arterial blood PaCO2 (DKA 31.8 +/- 6.7 mm Hg, NKH 34.2 +/- 8.3 mm Hg) did not differ between the two groups. Linear regression of the decrease in serum [K] value during treatment, (Delta[K]), on the presenting serum [K] concentration,([K]2 ), was: DKA, Delta[K] = 2.78 - 0.81 x [K]2 , r = -0.85, p < 0.001; NKH, Delta[K] = 2.44 - 0.71 x [K]2 , r = -0.90, p < 0.001. The slopes of the regressions were not significantly different. Stepwise logistic regression including both DKA and NKH cases identified the presenting serum [K] level and the change in serum [TCO2 ] value during treatment as the predictors of Delta[K] (R2 = 0.81). Hyperkalemia is a feature of severe hyperglycemia (DKA or NKH) occurring in patients on dialysis. Insulin administration brings about correction of DKA and return of serum [K] concentration to the normal range in the majority of the hyperglycemic episodes without the need for other measures. The initial serum [K] value and the change in serum [TCO2 ] level during treatment influence the decrease in serum [K] value during treatment of dialysis-associated hyperglycemia with insulin.

Ascites and venous carbon dioxide tensions in juvenile chickens of highly selected genotypes and native strains

A previous study by this group demonstrated that a high carbon dioxide tension in venous blood (pvCO2) of juvenile broiler chickens is a reliable predictor for ascites susceptibility.In a new experiment with five highly selected genetic stocks and two ascites resistant old breeds we studied levels and variability of pvCO2 within each stock at an early age. Effects of different selection traits (principally growth rate) between fast growing sire lines and slower growing dam lines and a commercial hybrid on blood gas (pCO2, pO2) tensions, pH and haematocrit in venous and arterial blood were examined at different ages and compared to values found in ascites resistant breeds. All birds were housed in floor pens in a climate controlled room and subjected to an ascites-predisposing cold environment.From each stock, 16 birds with the highest (high risk: HRc) and 16 birds with the lowest (low risk: LRc) pvCO2 values were selected at 12 days of age. These birds were marked for future blood sampling to determine changes in haematological characteristics with age and to relate these values to ascites susceptibility. At day 14, eight non-selected birds from each stock were randomly chosen for dissection to determine initial pulmonary arterial pressure index (API) values. Subsequently, all birds were allotted to 8 floor pens (13 birds per pen including two HRc and two LRc birds) per stock. Production performances from 104 birds per stock were measured from 16 to 33 days of age (feed intake (FI); feed conversion ratio (FCR); body weight (BW) at day 33). Mortality was recorded during the complete experimental period. At 5 wk of age, all HRc and LRc birds were necropsied and API values were recorded, which was used to classify the severity of the ascites syndrome.A convincing effect of pvCO2 values in juvenile chickens on API at 5 wk of age in modern lines confirmed results obtained in the previous study. At an early age, pvO2 values were much less predictive for high pulmonary pressure induced ascites at wk 5 than pvCO2 values. Hypercapnia combined with low blood pH values and followed by hypoxemia (inducing high haematocrit values) provoked a marked high incidence of ascites and high API values in modern breeds.A total absence of ascitic symptoms within native breeds corresponded with unchanged low API values during ageing from 12 to 33 days of age and with lower pCO2 values in venous and arterial blood compared to modern breeds at all ages. The pvCO2 difference (mean values) between HRc and LRc groups were similar for all modern lines irrespective of age and showed no relationship to growth rate. API, as a reliable indicator for ascites susceptibility, of modern breed chickens correlated with pvCO2 values, but not with growth rate. The high correlation between pvCO2 in juvenile chickens and API values at 5 wk of age indicated that a strong genetic selection pressure on low pvCO2 values at an early age will be an effective method to reduce decisively the occurrence of the ascites syndrome at sea level.

Umbilical Artery Blood Gas Parameters in Neonates With Early-Onset Seizures Who Die

Hypoxic–ischemic encephalopathy is diagnosed when newborn infants have certain neurologic abnormalities, including early-onset seizures, within 24–48 hours of admission to neonatal intensive care. The American College of Obstetricians and Gynecologists defines hypoxia severe enough to cause hypoxic–ischemic encephalopathy as a group of findings including a pH below 7.0; an Apgar score of 0–3 for longer than 5 minutes; neurologic sequelae; and cardiovascular, gastrointestinal, hematologic, pulmonary, or renal dysfunction. Early-onset seizures are the clearest indicator of moderate to severe disease with hypoxic–ischemic encephalopathy. Infants with this disorder are also at increased risk of cerebral palsy and neonatal death. This study sought to relate umbilical artery blood gas parameters to mortality in 47 infants at 32 or more weeks gestation who were admitted with early-onset seizures secondary to hypoxic–ischemic encephalopathy. Fourteen of 47 newborn infants admitted to the study died of complications related to hypoxic–ischemic encephalopathy. Maternal demographic factors were comparable regardless of whether the infant died or survived. Active resuscitation was attempted in all instances. There were no significant differences between infants who died and those who survived with respect to umbilical artery blood values of pH, base deficit, PCO2, or oxygen saturation. Levels of PO2 were significantly higher in neonates who died than in survivors (18.4 vs. 12.3). Neither umbilical artery blood pH nor base deficit predicted neonatal deaths in the present study of infants having hypoxic–ischemic encephalopathy and early-onset seizures. A high PO2 in newborn infants who subsequently die may reflect an impaired inability to extract oxygen from the blood. The question of whether patterns of change in PCO2 predict the development of neonatal encephalopathy awaits further investigation.

The pH Dependency of the Binding of Drugs to Plasma Proteins in Man

An analysis of pH-induced changes of drug binding may contribute to the understanding of the mechanisms involved and the clinical relevance. A literature search was performed, and acceptance criteria set up, to select reported data for quantitative evaluation. The relationship between percentage of unbound drug, fu, and pH was analyzed, and the relevance of physicochemical characteristics of the ligand drugs and the importance of hydrogen ion-induced changes in plasma proteins for the pH sensitivity of the binding were evaluated. With all basic and the majority of acidic drugs, fu depended linearly on pH. Basic drugs showed a consistent behavior with fu decreasing with increasing pH. Acidic compounds behaved differently: With some, fu increased, and with others fu decreased, with pH, and with a third group of acids fu was pH independent. Large differences in the pH sensitivity of the plasma protein binding among individual compounds were found. The fu in plasma for some bases and acids increased up to 136% and 95%, respectively, at pH values seen in severe acidemia or alkemia. These changes in fu could be clinically relevant with narrow-therapeutic-range drugs. Physicochemical properties and other characteristics of the ligands affect the pH sensitivity of the interaction with plasma proteins, but there was clear evidence indicating that pH-induced changes in the plasma proteins are also involved in the observed pH-dependent interaction with ligands. It is generally accepted that the unbound, free fraction in whole blood or plasma is an important determinant of the pharmacokinetics and pharmacodynamics of drugs. pH-dependent protein binding and consequent changes in the free fraction have been reported for many drugs. From a basic science point of view, the systematic study of pH-induced perturbations of the drug-protein interaction may provide insight into the mechanism and forces involved in the binding of drugs to plasma proteins. From a clinical viewpoint it may be of interest to know the extent of pH-induced changes in the unbound fraction of drugs under extreme acidemic or alkalemic conditions. Arterial blood pH values compatible with life reportedly range between 6.7 and 8.0. pH values as low as 6.3 have been measured in survivors of drowning accidents. To the best knowledge of the authors, a review and interpretation of pH-associated changes in the protein binding of drugs has not been attempted to date. The goals of this investigation were to (1) review published results of studies that determined the impact of pH changes on the protein binding of drugs in man, (2) select representative data using predetermined criteria, (3) determine relevant factors impacting the pH sensitivity of the drug-protein interaction, and (4) attempt to interpret the results and their clinical relevance.

Cardiopulmonary and acid–base effects of desflurane and sevoflurane in spontaneously breathing cats

The cardiopulmonary effects of desflurane and sevoflurane anesthesia were compared in cats breathing spontaneously. Heart (HR) and respiratory (RR) rates; systolic (SAP), diastolic (DAP) and mean arterial (MAP) pressures; partial pressure of end tidal carbon dioxide (PETCO2), arterial blood pH (pH), arterial partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2); base deficit (BD), arterial oxygen saturation (SaO2) and bicarbonate ion concentration (HCO3) were measured. Anesthesia was induced with propofol (8+/-2.3mg/kg IV) and maintained with desflurane (GD) or sevoflurane (GS), both at 1.3 MAC. Data were analyzed by analysis of variance (ANOVA), followed by the Tukey test (P<0.05). Both anesthetics showed similar effects. HR and RR decreased when compared to the basal values, but remained constant during inhalant anesthesia and PETCO2 increased with time. Both anesthetics caused acidemia and hypercapnia, but BD stayed within normal limits. Therefore, despite reducing HR and SAP (GD) when compared to the basal values, desflurane and sevoflurane provide good stability of the cardiovascular parameters during a short period of inhalant anesthesia (T20-T60). However, both volatile anesthetics cause acute respiratory acidosis in cats breathing spontaneously.

Frequency of plain film abnormalities and some clinical findings of acute pulmonary embolism – correlation with severity of pulmonary arterial obstruction

Background: The aim of the study was to find out if chest x-ray abnormalities and some clinical signs and findings in patients with acute pulmonary embolism (PE) correlate with the degree of pulmonary arterial obstruction (CT obstruction index – CTOI) determined with scoring system on spiral CT angiograms (SCTA). Material and methods: In 41 pts (16 men, 25 women; age range 20–89 years, mean 65 years) with SCTA proven acute PE, plain chest films were retrospectively reviewed for signs of acute PE. A scoring system based on site and degree of arterial obstruction enabled measurement of severity of obstruction on SCT angiograms. Some clinical signs (sudden onset dispnea, chest pain, syncope), ECG, pH and pCO2 of arterial blood were evaluated and compared between group with major PE (10 pts with CTOI > 40%) and the rest (31 pts with CTOI 40% (60% vs. 22.5%; p value < 0.05). There was no difference in frequency of clinical signs, pH and pCO2 of arterial blood between patients with major and minor PE. Conclusions: In pts with CT proven acute PE, oligemia on chest x-ray and ECG signs of right ventricular strain correlate with severity of pulmonary arterial obstruction. Clinical simptoms, pH and pCO2 of arterial blood show no correlation with degree of pulmonary arterial obstruction.

Circulating levels of the long pentraxin PTX3, an acute phase mediator of innate immunity, in acute lung injury/acute respiratory distress syndrome: functional and prognostic correlations

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is characterized by an important inflammatory reaction involving both lungs, often spreading systemically. Pentraxin 3 (PTX3) has recently been described as a mediator of the acute phase of innate immunity. It belongs, together with C-reactive protein (CRP), to the pentraxin superfamily. PTX3 is produced by endothelial cells, fibroblasts, mononuclear phagocytes and dendritic cells in response to primary inflammatory signals (IL-1, tumor necrosis factor, LPS). Its involvement in the pathogenesis of ALI/ARDS seems probable and potentially interesting for the pathophysiology, the diagnosis and possibly the therapy of the syndrome. We measured PTX3 levels, by an ELISA test, in the sera of 25 patients affected by ALI/ARDS. We also collected data related to etiology, pulmonary mechanics, gas exchange, systemic inflammatory involvement, microbiology, blood cells and the outcome of these patients. PTX3 was markedly elevated in all 25 patients (average 111.07 ± 192.01 ng/ml; range 4.94–922.91 ng/ml). In no patient were PTX3 levels lower or equal to the physiological threshold of 2 ng/ml. Levels of logPTX3 were significantly different between survivor and nonsurvivor patients (1.465 ± 0.529 log ng/ml vs 1.950 ± 0.643 log ng/ml; P = 0.05). Patients with two or more organ failures (besides the lung) also had logPTX3 levels significantly higher than patients with just one additional organ failure (1.936 ± 0.597 log ng/ml vs 1.423 ± 0.542 log ng/ml; P < 0.04). The same was true when PTX3 levels in patients with septic shock were compared with PTX3 levels in patients without shock (262.465 ± 350.727 ng/ml vs 63.257 ± 70.261 ng/ml; P < 0.03). PTX3 and logPTX3 were correlated with body temperature (r = 0.56 P < 0.01; r = 0.51 P = 0.01) and with arterial blood pH (r = -0.53 P < 0.01; r = -0.53 P < 0.01). We have underlined a relationship between circulating levels of PTX3 and some markers of the severity of systemic involvement. PTX3 could be an indicator of the gravity of the systemic inflammatory reaction and of unfavourable outcome in ALI/ARDS patients.

Defibrillation Effects of Intravenous Nifekalant in Patients with Out‐of‐Hospital Ventricular Fibrillation

Nifekalant (NF), a pure K(+) channel blocker developed in Japan, has been reported to be effective in the treatment of life-threatening ventricular arrhythmias. We studied its efficacy in 18 men and 4 women with out-of-hospital ventricular fibrillation (VF) admitted to our emergency department between August 2001 and March 2004. The number of DC shocks delivered for out-of-hospital VF, serum Na(+) and K(+), arterial blood pH, and base excess were compared in 8 patients treated with NF, 0.3 mg/kg i.v. followed by a continuous intravenous (group N) versus 14 patients treated with lidocaine, 2 mg/kg, i.v. (group C). The two groups were similar with respect to their baseline characteristics. Sinus rhythm returned in 5 of 8 patients in group N versus 2 of 14 patients in group C (P < 0.05). These seven patients were admitted to the intensive care unit, though all died within 1 month. The results of this study suggest that NF may be effective in defibrillation of out-of-hospital VF, though controlled studies are needed to confirm our observations.

Effect of High Doses of Sodium Bicarbonate in Acute Organophosphorous Pesticide Poisoning

The sodium bicarbonate (NaHCO3) dosage used in treating the patients with organophosphorous pesticide (OP) poisoning did not result in sufficient alkalinization of the blood. We thus investigated the effects of higher doses by infusion (5 mEq/kg over 1 hour, followed by 5–6 mEq/kg daily until recovery or death) to maintain the arterial pH between 7.45 and 7.55. There were 26 (14 M and 12 F) patients aged 24.1 ± 9.7 years and 27 (16 M and 11 F) aged 25.7 ± 9.1 years in the test and control groups, respectively. Arterial blood pH of the test group (7.48 ± 0.02) was much higher (p < 0.0001) than the controls (7.36 ± 0.02). The total atropine doses used for the control patients (129.45 ± 61 mg) was significantly (p = 0.048) higher than the controls (93.4 ± 59.1 mg). Hospitalization days were statistically higher (p = 0.037) in the controls (5.59 ± 1.97 days) than in the bicarbonate group (4.33 ± 1.99 days). Infusion of high doses of NaHCO3 appears to be beneficial in treatment of patients with OP poisoning.

Relationships between umbilical cord arterial blood pH levels at delivery and subsequent neurological outcomes in children

Relationships between umbilical cord arterial blood pH levels at delivery and subsequent neurological outcomes in children

Relationships between fetal inflammatory response syndrome and umbilical cord arterial blood pH levels

Relationships between fetal inflammatory response syndrome and umbilical cord arterial blood pH levels

Effect of dietary-induced metabolic acidosis and ovariectomy on bone mineral density and markers of bone turnover

Dietary-induced metabolic acidosis (DIMA) has been implicated as a significant confounder in the development of osteoporosis. Twenty-four mature ewes were randomly assigned to four groups of six sheep. Group 1 consumed a control diet (ND); group 2 consumed a normal diet (ND) and had ovariectomy (OVX), group 3 consumed a diet that induced metabolic acidosis (MA), without OVX, and group 4 consumed a diet that induced MA, with OVX. The study was conducted over 180 days and the sheep were maintained on the assigned diet throughout. Sheep were weighed and bone mineral density (BMD) was measured, using dual-energy X-ray absorptiometry (DEXA), on days 0 and 180. Serum bone alkaline phosphatase (BAP), urine deoxypyridinoline (DPD), and fractional excretions (FE) of Ca and P were determined on days 0, 90, and 180. Arterial blood pH was determined on day 180. Analysis consisted of a two-way analysis of variance for repeated measures with significance set at P < or = 0.05. Body weights, serum BAP, and urine DPD were not influenced by either diet or OVX status. DIMA did significantly increase urinary FE of Ca and P and significantly decreased lumbar BMD and arterial pH. Arterial pH remained within physiologic normal limits. DIMA was a more potent cause of calcium wasting than OVX over the time frame of this study. Sheep appear to be sensitive to DIMA and will therefore be a useful animal model to study the influence of diet on the development of osteoporosis. The specific mechanisms through which DIMA exerts its influence are still unknown and are the subject of ongoing studies.

Accuracy and performance of a modified continuous intravascular blood gas monitoring device during thoracoscopic surgery

Objective: The only commercially available continuous intravascular blood gas monitoring system for adults, the Paratrend (Diametrics Medical Inc, High Wycombe, UK), was modified by the manufacturer to the Paratrend 7+ (PT7+) in 1999. The aim of this study was to evaluate the modified probe over a wide range of blood gas and pH values during thoracoscopic surgery in a similar setup as done with the previous model. Design: Prospective methods comparison study. Setting: University hospital. Participants: Twenty-three patients. Interventions: Elective thoracoscopic surgery. Measurements and main results: One hundred thirteen PT7+ readings and their corresponding arterial blood gas and pH measurements (ABGA) were evaluated. The ranges for ABGA values were 50 to 474 mmHg for PO 2, 29 to 58 mmHg for PCO 2, and 7.28 to 7.49 for pH. Bland and Altman analysis revealed a bias ± 2 standard deviation of −20 ± 86 mmHg for PO 2, 3 ± 9 mmHg for PCO 2, and −0.01 ± 0.06 for pH. No specific complications attributable to the probe were observed. Conclusion: In patients undergoing thoracoscopic surgery with rapidly changing blood gas parameters, the PT7+ device is a valuable trend indicator and hence may be helpful for clinical decision making. However, the underestimation of PO 2 values by 20 mmHg on average and the wide limits of agreement documented in this study must be regarded as limiting factors.

Computerized cardiotocography in the management of intrauterine growth restriction associated with Doppler velocimetry alterations

Objective: To verify the reliability of computerized cardiotocography (cCTG) in the prediction of the oxygen metabolism status of fetuses with growth restriction and Doppler velocimetry alterations. Methods: From 24 third-trimester cesarean section performed because of intrauterine growth restriction (IUGR) and Doppler velocimetry alterations, there were 11 cases of fetal heart rate alterations (Dawes–Redman criteria were not satisfied) and 13 cases of reactive cCTG. Fetal lung maturity was detected by amniocentesis and blood samples for umbilical blood gas analysis (UBGA) were collected before the first neonatal breath from the umbilical artery in a double-clamped segment of the cord. Results: Umbilical cord gas analysis showed arterial cord blood pH to be 7.20 or less in 11 newborns (45.8%), 7.10 or less in 6 (25%), and 7.00 or less in 3 (12.5%). Linear regression analysis showed short-term variation (STV) in the fetal heart rate to be significantly correlated with umbilical artery pH ( r=0.49; P=0.01) and pCO 2 ( r=−0.50; P=0.01). There were no significant correlations between cCTG and the other UBGA parameters considered. Receiver operator curves permitted to calculate the STV values at which pathological neonatal UBGA values can be expected (pH<7.00 and pCO 2>80 mmHg). A short-term variation less than 4.5 ms was found to predict acidemia with a sensitivity of 100% and a specificity of 70% (positive predictive value, 33%; negative predictive value, 100%), and hypercarbia with a sensitivity of 100% and a specificity of 77.8% (positive predictive value, 55.6%; negative predictive value, 100%). Conclusion: In view of the results of this study, 4.5 ms for STV may be a threshold below which timing of delivery should be decided in cases of fetal growth restriction.

“Pseudoinfarction” Pattern Due to Hyperkalemia

A 38-year-old man presented to the emergency department with nausea, vomiting, and epigastric pain. The patient had type 1 diabetes mellitus and was being treated with insulin. He was also taking lisinopril for the treatment of hypertension. The initial electrocardiogram (Panel A) revealed sinus tachycardia and ST-segment elevation in leads V1 to V3 — findings highly suggestive of acute anteroseptal myocardial infarction. Peaked T waves were noted in leads II, III, aVF, and V3 to V6. The serum glucose concentration was 839 mg per deciliter (46.6 mmol per liter), the arterial blood pH was 7.21, . . .

Nucleated Red Blood Cells in Uncomplicated Prolonged Pregnancy

Elevated counts of nucleated red blood cells (NRBCs), as well as prolongation of pregnancy, have been suggested as predictors of adverse perinatal outcome. However, the association between these 2 variables has received only minimal attention. We sought to evaluate fetal NRBCs in prolonged pregnancies. Umbilical cord blood was prospectively collected at delivery from 75 prolonged (at or beyond 287 days) pregnancies. One hundred and fifty term deliveries (260-286 days) served as controls. All pregnancies were accurately dated with the use of first-trimester sonography. Fetal biophysical profile testing was initiated at 40 weeks of gestation. Patients were delivered if they were in spontaneous labor or the biophysical profile was nonreassuring or by 42 weeks of gestation. Nucleated red blood cell counts were expressed per 100 white blood cells (WBC). Umbilical artery pH studies, as well as other demographic and clinical variables, were obtained. Prolonged pregnancy was associated with a significantly increased incidence of induction of labor and a greater birth weight. There were no other differences between the study group and controls. The median NRBCs per 100 WBCs in prolonged pregnancy was not significantly elevated over the term values (median 3, range 0-35 versus median 3, range 0-34, respectively; P =.25). Neonatal outcome was also comparable between groups. The univariate regression analysis demonstrated a significant association between elevated NRBC counts and low arterial cord blood pH (P <.008, R = 0.175), elevated base excess (P =.02, R = 0.149), low platelet counts (P =.046, R = 0.134), and male gender (P =.028). Stepwise regression analysis revealed that low arterial cord blood pH and male gender were the only independent variables predicting elevated NRBC counts at birth. The findings of this study suggest that elevated NRBC counts are associated with specific pregnancy complications rather than uncomplicated prolonged pregnancies in general.

Repair of the descending thoracic aorta: impact of open distal anastomosis technique on spinal cord perfusion, neurological outcome and spinal cord histopathology☆

We investigated the impact of equilibrating distal aortic pressure with atmospheric pressure (open distal anastomosis) on spinal cord perfusion, neurological outcome and spinal cord histopathology in a rat model of descending thoracic aortic surgery. Proximal thoracic aortic occlusion was obtained in Sprague-Dawley rats by inflating the balloon of a 2F Fogarty catheter introduced through the left femoral artery. Rats were separated into three groups: sham-operation (n = 5) without balloon inflation, control (n = 15) with inflation of the balloon, and open distal (n = 15) with inflation of the balloon combined with incision of the right femoral artery to allow free drainage of distal aortic blood. Balloon inflation was maintained for 15 min. Rectal temperature, arterial blood gases and pH, distal arterial blood pressure (DABP) and lumbar spinal cord blood flow (SCBFl) were recorded throughout the procedure. Neurobehavioral status was assessed daily using a 0-5 scale and rats were sacrificed after 48 h of reperfusion and their spinal cord harvested for histopathology and immunohistochemistry for microtubule-associated protein-2 (MAP-2). DABP and SCBFl values were lower during thoracic aortic occlusion in the open distal group, compared to the control group (P < 0.001). Paraplegia and mortality rates were dramatically increased in the open distal group (87.7 and 46.6%, respectively) compared to the control group (0 and 6.6%, respectively, (P < 0.001 and 0.02). Severe metabolic acidosis and bowel infarct were also more frequent in the open distal group (P < 0.001). Sham-operated and control rats had virtually normal spinal cords, whereas rats in the open distal group had severe ischemic injury throughout gray matter. Equilibrating distal arterial pressure with atmospheric pressure during thoracic aortic occlusion decreased spinal cord blood flow, increased mortality and worsened spinal cord injury in rats. These results suggest that the open distal anastomosis technique should be used with caution in patients undergoing repair of the descending thoracic or thoracoabdominal aorta.

Laboratory tests to determine the cause of hypokalemia and paralysis.

Hypokalemia and paralysis may be due to a short-term shift of potassium into cells in hypokalemic periodic paralysis (HPP) or due to a large deficit of potassium in non-HPP. Failure to make a distinction between HPP and non-HPP may lead to improper management. Therefore, we evaluated the diagnostic value of spot urine tests in patients with hypokalemia and paralysis during 3 years. Before therapy, the urine potassium concentration, potassium-creatinine ratio, and transtubular potassium concentration gradient were determined in a second voided urine sample. Forty-three patients with hypokalemia and paralysis were identified: 30 had HPP and 13 had non-HPP. There was no significant difference in the plasma potassium or bicarbonate concentrations and in the pH of arterial blood between the 2 groups. All but 2 patients in the non-HPP group had urine potassium concentration values less than 20 mmol/L. Although the potassium concentration was significantly lower in the HPP group, there was some overlap. In contrast, the transtubular potassium concentration gradient and potassium-creatinine ratio differentiated patients with HPP vs non-HPP. Although only a mean +/- SD of 63 +/- 36 mmol of potassium chloride was administered in the patients with HPP, rebound hyperkalemia (>5 mmol/L) occurred in 19 (63%) of these 30 patients. Calculating the transtubular potassium concentration gradient and potassium-creatinine ratio provided a simple and reliable test to distinguish HPP from non-HPP. Minimal potassium chloride supplementation should be given to avoid rebound hyperkalemia in patients with HPP.