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PubMed1986

Renal bicarbonate handling in low birth weight infants during metabolic acidosis.

We studied the fractional excretion of bicarbonate (FE HCO-3) in 10 low birth weight infants aged 1-6 days during metabolic acidosis (base excess greater than or equal to -5 mEq/l) and during subsequent sodium HCO-3 infusion. The mean birth weight was 1,095 g; the mean gestational age was 29 weeks. The ability to decrease urine pH to less than 5.5 and FE HCO-3 to less than 1% during metabolic acidosis was not limited by low gestational age or birth weight. After HCO-3 therapy, all infants corrected their negative base excess, and plasma HCO-3 increased significantly. All infants with blood pH less than or equal to 7.22 or PaCO2 greater than or equal to 50 mm Hg had minimal or absent FE HCO-3. Infants with elevated PaCO2 and mild or absent acidosis also had complete HCO-3 tubular reabsorption. These results suggest that the HCO-3 tubular reabsorption is adequate during metabolic and/or respiratory acidosis in low birth weight infants.

Acidosis↗
PubMed2001

Cell-cell coupling in CO(2)/H(+)-excited neurons in brainstem slices.

The indirect and direct electrical and anatomical evidence for the hypothesis that central chemoreceptor neurons in the dorsal brainstem (solitary complex, SC; locus coeruleus, LC) are coupled by gap junctions, as reported primarily in rat brainstem slices, and the methods used to study gap junctions in brain slices, are critiqued and reviewed. Gap junctions allow intercellular communication that could be important in either electrical coupling (intercellular flow of ionic current), metabolic coupling (intercellular flow of signaling molecules), or both, ultimately influencing excitability within the SC and LC during respiratory acidosis. Gap junctions may also provide a mechanism for modulating neuronal activity in the network under conditions that lead to increased or decreased central respiratory chemosensitivity. Indirect measures of electrical coupling suggest that junctional conductance between chemosensitive neurons is relatively insensitive to a broad range of intracellular pH (pH(i)), ranging from pH(i) approximately 7.49 to approximately 6.71 at 35-37 degrees C. In contrast, further reductions in pH(i), down through pH(i) approximately 6.67, abolish indirect measures of electrical coupling.

Animals↗
PubMed1989

Blood gas tensions, acid-base status and cardiovascular function in miniature swine anaesthetized with halothane and methoxyflurane or intravenous metomidate hydrochloride.

Göttingen mini-pigs were given atropine and anaesthetized with one of the following drug combinations: 1) azaperone + metomidate, 2) acepromazine + thiopentone for endotracheal intubation, followed by halothane + methoxyflurane in oxygen. Respiration rate, arterial O2 and CO2 tensions, arterial pH, mean arterial blood pressure and heart rate were recorded at 15 min. intervals from 30 to 120 min. after the induction of anaesthesia. The azaperone-metomidate combination, which requires continuous intravenous access, caused a mild respiratory acidosis, but acid-base status was stable, whereas blood pressure and heart rate rose steadily throughout the observation period. The second combination depressed respiratory and cardiovascular function, but the condition of the animals did not deteriorate further during 2 hrs of surgical anaesthesia. Endotracheal intubation for inhalation anaesthesia should, however, be performed after a single injection of metomidate, as thiopentone tended to cause respiratory arrest.

Acid-Base Equilibrium↗
PubMedDate not supplied

Bronchointerstitial pneumonia and respiratory distress in young horses: clinical, clinicopathologic, radiographic, and pathological findings in 23 cases (1984-1989).

Twenty-three foals, between 1 and 7 months old, with signs of acute respiratory distress, were examined at the Veterinary Medical Teaching Hospital (VMTH), University of California, Davis, between 1984 and 1989. Characteristic features included sudden onset of severe respiratory distress and tachypnea, cyanosis unresponsive to nasal oxygen, pyrexia, hypoxemia, hypercapneic respiratory acidosis, poor response to treatment, and histopathologic lesions of bronchiolitis and bronchointerstitial pneumonia. Seven of the 23 foals were normal before the onset of respiratory distress, 3 foals were found dead, and 13 foals were being treated for respiratory tract infections at the time of presentation. Laboratory data obtained for 13 horses showed increased plasma fibrinogen concentration (630.7 +/- 193 mg/dL), leukocytosis (18,607 +/- 7,784/microL), and neutrophilia (13,737 +/- 8,211/microL). Thoracic radiographs showed a diffuse increase in interstitial and bronchointerstitial pulmonary opacity and, in 5 foals, an alveolar pulmonary pattern of increased density was also seen. In 3 foals heavy interstitial infiltration proceeded to a coalescing nodular radiographic appearance. Microbiological culture of tracheobronchial aspirates (TBA) from 9 foals yielded bacterial growth, but no one bacterial species was consistently isolated. Microbiological culture of postmortem specimens of the lung from 6 foals yielded growth of bacteria that included Escherichia coli, Enterobacter spp., Proteus mirabilis, Klebsiella pneumoniae, Rhodococcus equi, or beta-hemolytic Streptococcus spp. Tracheobronchial aspirates from 4 foals and lung samples collected from a further 4 foals at necropsy yielded no bacterial growth. Cultures were not taken from two foals premortem or postmortem. Virologic examination of TBA, lung tissue, or pooled organ tissue from 12 foals was negative. Viral culture of TBA from 1 foal showed cytopathic effects and positive immunofluorescence for equine herpes virus type II (EHV-II). In addition to the 3 foals that were found dead, 11 foals died or were euthanatized. Pathologic lesions were limited to the lungs in 50% of the foals; the remainder also had bowel lesions suggestive of hypoxic injury. The predominant histopathologic pulmonary lesions included bronchiolitis, bronchiolar and alveolar epithelial hyperplasia, and necrosis. Many bronchioles were filled with mucoid and fibrinocellular exudate. The peribronchiolar interstitium and adjacent alveolar spaces were also infiltrated with inflammatory cells and contained proteinaceous edema fluid. Type II cell hyperplasia and hyaline membrane formation were observed in the majority of foals and in 2 foals alveolar multinucleate giant cells were also present.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

The implementation of a nurse-provided, ward-based bilevel non-invasive ventilation service.

Bilevel non-invasive ventilation (NIV) is now standard of care for patients with acute hypercapnic respiratory failure (AHRF), and has an increasing role to play in patients with stable chronic hypercapnic respiratory failure (CHRF). The institution of an NIV service in a hospital setting requires major infrastructural and multidisciplinary input to be effective. This paper describes our experiences in setting up a 24-hour, nurse-provided, ward-based NIV service in a new acute teaching hospital in Dublin over a 39-month period. In addition, we provide audit data on 78 patients with AHRF treated with NIV by this service over this time period. The majority of patients (65) had their respiratory acidosis corrected and were discharged home; 11 patients failed NIV and were intubated and mechanically ventilated in the ITU; 13 patients died, 8 from respiratory causes and 5 from non-respiratory causes, indicating the critical nature of this condition.

Adult↗
PubMed1990

Biochemical pathways and modulators of renal ammoniagenesis.

The renal proximal tubule contains a variety of biochemical pathways, which can metabolize glutamine, the major substrate for renal ammoniagenesis. The intramitochondrially located phosphate-dependent glutaminase (PDG) pathway, rather than the various cytosolic pathways, appears to play the predominant role in regulating the rate of renal NH3 production. Acute acidosis stimulates NH3 production by activating alpha-ketoglutarate dehydrogenase and secondarily glutamate dehydrogenase; whereas the adaptation to chronic metabolic acidosis results primarily from enhanced glutamine transport into the mitochondria and possibly increased activity of PDG. There is no adaptation of ammoniagenesis to chronic respiratory acidosis, because the proximal tubular intracellular pH is not decreased. Alkalosis suppresses NH3 formation but the precise mechanism is not clarified. Ammoniagenesis can be modulated independent of acid-base status by a variety of factors including potassium homeostasis, TCA cycle intermediates, hormones which increase cAMP, prostaglandin F2 alpha, insulin, growth hormone, angiotensin II, corticosteroids, aldosterone, and tubular flow rate.

Acidosis, Renal Tubular↗
PubMedDate not supplied

[What effect does leg position in breech presentation have on mode of delivery and early neonatal morbidity?].

The objective of the present study is to establish whether the position of the legs in breech presentation deliveries affects the vaginal or abdominal mode of surgical delivery and the early neonatal morbidity. The patient population investigated (n = 266) comprised 163 primiparae (61.3%) and 103 multiparae (38.7%). Of the 266 term infants (more than 37 complete WOP) with breech presentation, 71.3% (127/178) could be delivered vaginally from a simple pelvic presentation and 55.3% (42/76) from an incomplete or complete footling presentation. The average duration of labor was 460 minutes in a pelvic presentation delivery, and 400 minutes in a footling presentation delivery. The rate of acidosis (pHNA < 7.20) was 26% in the neonates delivered from the pelvic presentation as compared to 11.9% in the footling presentation deliveries. The number of neonates with a 5/10 minute APGAR score of seven points was 0/0% in pelvic and 4.8/2.4% in footling presentation. Of the neonates delivered from pelvic presentation, 10.2% (13/127) were moved to the neonatology department as compared to 14.3% (6/42) babies delivered from footling presentation. A secondary Cesarean section was indicated in 28.7% of pelvic presentation deliveries commenced vaginally (51/178) and in 44.7% of the footling deliveries (34/76). The rate of acidosis was 49% (25/51) in the babies with pelvic presentation and 21% (7/34) in the babies with footling presentation. The percentage of neonates with respiratory depression (5/10 minute APGAR score < 7 points) was 3.9/2.9% in the babies delivered from pelvic presentation and 2/0% in the babies delivered from footling presentation. Correspondingly, the rate of transfer to the neonatology ward was extremely high: 33.3% (17/51) of the pelvic presentation babies and 8.8% (3/34) of footling babies. In 11 pregnant women (5.8%) with a fetus in pelvic presentation, a primary Cesarean section was indicated, in half of these cases (n = 5) because of "suspicion of a discrepancy", three times at request of the patients and three based on fetal and on maternal indication. Because she had rejected vaginal delivery, primary Cesarean section was performed in one pregnant mother (1.3%) with a fetus in footling presentation. Fetuses with simple pelvic presentation at term were more frequently delivered vaginally than fetuses in footling presentation (71.3% compared to 55.3%). The rate of respiratory acidosis was higher in the neonates with pelvic presentation than those with footling presentation (26% as compared to 11.9%). They compensated this acidotic metabolism within a short time, so that the transfer to the neonatology ward was only temporary. The same applied to the babies delivered by secondary Cesarean section.

Adult↗
PubMed1998

Helium and carbon dioxide pneumoperitoneum in patients with pheochromocytoma undergoing laparoscopic adrenalectomy.

Insufflation with helium is used to prevent respiratory acidosis, hypercapnia, and cardiovascular instability associated with carbon dioxide (CO2) pneumoperitoneum. The aim of this prospective study was to compare CO2 with helium pneumoperitoneum with special reference to respiratory and hemodynamic changes at different times during the operation. Altogether 22 pheochromocytoma patients undergoing laparoscopic adrenalectomy (LpA) were included using CO2 in 11 patients (CO2LpA) and helium in 11 patients (HeLpA). The insufflation pressure was 12 mmHg. The two groups were comparable with regard to demographic data and preoperative management. CO2 and helium insufflation were associated with similar catecholamine increase. The most striking significant increase compared with the baseline was observed during tumor isolation: The mean plasma epinephrine (EPI) and norepinephrine (NE) levels increased 32.86-fold and 25.92-fold, respectively, in the CO2LpA patients and 27.43-fold and 18.46-fold, respectively, in the HeLpA patients. HeLpA did not result in significant hypercarbia or acidosis at any measured intraoperative point; this was without any alteration in minute ventilation to maintain these normal PaCO2, excess base (EB), and pH values. Significant increases of mean arterial pressure, pulmonary arterial pressure, pulmonary vascular resistance index, PaCO2, EB, and acidosis were seen in the CO2LpA patients at the time of tumor isolation and tumor removal compared with those in HeLpA patients. No patient required conversion to open surgery. There were no significant differences between CO2LpA and HeLpA regarding mean operative time (117.50 +/- 93.68 vs. 106.87 +/- 16.60 minutes), mean blood loss (168.54 +/- 78.63 vs. 142.02 +/- 109.26 ml), hospital stay (4 days), the need for analgesics, or mean time required to return to normal activity (12 days). There was one wound infection in the HeLpA group and one wound hematoma and one case of atelectasis in the CO2LpA group. Helium may be the agent of choice for abdominal insufflation in patients undergoing LpA for pheochromocytoma, eliminating the adverse hemodynamic and respiratory changes associated with CO2 insufflation.

Adrenal Gland Neoplasms↗
PubMed1991

Extracellular and intracellular acid-base effects of submergence anoxia and nitrogen breathing in turtles.

We compared extracellular and intracellular acid-base state in turtles (Chrysemys picta bellii) subjected to anoxic submergence to turtles made anoxic by N2-breathing. Measurements made on control animals and on animals after 1, 2, 4, or 6 h of anoxia included blood pH, PO2, PCO2, and lactate as well as liver, heart, skeletal muscle, and brain pHi (using DMO equilibration), lactate, and glycogen concentrations. We hypothesized that the anaerobic metabolic rate of submerged turtles would be depressed by the more severe extra- and intracellular acidosis, and that this would be indicated by reduced lactate accumulation and glycogen depletion. Submerged turtles became extremely acidemic due to a combined metabolic and respiratory acidosis and had significantly lower arterial pH than N2-breathing animals (6.98 and 7.34, respectively, after 6 h). In spite of this disparity in pHa, 6 h pHi values for liver, heart, and brain were similar. Likewise, our data on glycogen depletion and lactate accumulation at h 6 in these tissues suggest no dramatic differences in anaerobic metabolic rate. While skeletal muscle pHi was somewhat lower at h 6 in the submerged group (6.73 vs 6.91 for N2-breathers), we observed no differences in either glycogen depletion or lactate accumulation in this tissue between our two treatments. Thus, at h 6, in spite of a 0.37 pH unit difference in pHa and a nearly 70 mm Hg difference in arterial and presumably cytosolic PCO2, pHi and tissue lactate and glycogen concentrations were similar. These results can be explained if the in vivo intracellular buffer values (beta) of turtle tissues are very high. We conclude that extracellular acid-base state is not necessarily reflected intracellularly in vivo in turtles and care must be taken in extrapolating from one compartment to another when attempting to make inferences about metabolic depression or acid-base regulation in this species.

Acid-Base Equilibrium↗
PubMed1984

Pulmonary and hematologic changes in swine with Mycoplasma hyopneumoniae pneumonia.

Studies were made of the physiologic changes in the lung of young growing pigs intratracheally inoculated at 5.5 to 6 weeks of age with Mycoplasma hyopneumoniae. Hematologic changes also were studied. Studies were performed at the 4th, 5th, and 6th weeks after inoculations were done. The inoculated pigs had a marked decrease in body weight gain. There were no significant changes in the heart rate, respiratory rate, and rectal temperature, even though at necropsy the apical, cardiac, and diaphragmatic lobes of the lungs of inoculated pigs had scattered, but well-demarcated, pneumonic lesions. The lungs were edematous and increased in weight, compared with those of control (noninoculated) pigs. There were several changes in respiratory functions in the inoculated animals, including significant increases in esophageal pressure negativity, expiratory flow rate, tidal and minute volumes, and work of breathing and significantly less oxygen consumption. Inspiratory flow rate and airway resistance were markedly increased. The elasticity of infected lungs was reduced, as shown by notable decreases of dynamic lung compliance. According to blood gas analyses, acid-base balance had changed in the inoculated pigs. Arterial blood pH, arterial partial pressures of O2 and CO2, and arterial concentration of HCO3- decreased. To some degree respiratory acidosis indicated by a significant decrease of base excess was evident in the blood of inoculated pigs. As a result, inoculated animals required hyperventilation (compensatory respiratory alkalosis) to maintain the pH of arterial blood near a physiologically normal value. The pigs with mycoplasmal pneumonia showed no drastic hematologic changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Necrotizing tracheobronchitis in ventilated newborn infants].

BACKGROUND: Necrotizing tracheobronchitis is a severe complication observed in some mechanically ventilated neonates. CASE REPORT: A twin premature (GA = 31 weeks), weighing 1,500 g required oral endotracheal intubation for mechanical ventilation because he suffered from respiratory distress syndrome. He was given indomethacin on day 4 for patent ductus arteriosus. Progressive weaning of ventilation on day 9 was dramatically complicated by hypoxia, respiratory acidosis and right pneumothorax. Immediate endoscopy showed total obstruction of trachea by necrotic secretions the suction of which was followed by rapid improvement of the respiratory condition. Bacterial examination of secretions showed coagulase-negative staphylococcus. The patient was given steroids + antibiotics. Prolonged ventilation resulted in bronchopulmonary dysplasia and the patient was only extubated at week 12 after a normal endoscopic control. CASE REPORT: A premature girl (GA = 32 weeks), weighing 1,800 g required oral endotracheal intubation for mechanical ventilation because she suffered from respiratory distress syndrome. The respiratory condition worsened on day 3, requiring tracheography which showed distal tracheal obstruction. Immediate endoscopy showed thin, adherent and necrotic membranes which were removed by suction. The patient was given steroids +antibiotics and was extubated on day 14 after a normal endoscopic control. CONCLUSIONS: This iatrogeneous complication must be recognized in a ventilated infant when the respiratory condition dramatically worsens. Emergency bronchoscopy permits endotracheal suction of necrotic secretions.

Bronchitis↗
PubMed1993

[Complications in urological laparoscopic surgery].

Laparoscopic surgery is often associated with complications which never occur in open conventional surgery. We investigated operative and postoperative complications in urological laparoscopic surgery. From February 1990 to November 1992, 91 laparoscopic operations were performed, including 62 varicocelectomies, 5 pelvic lymphadenectomies, 6 adrenalectomies, 5 simple nephrectomies, 2 radical nephrectomies, 1 staged Fowler-Stephens operation and 10 laparoscopies for cryptorchidism or other disorders. The patients ranged from 3 months to 77 years old. Nine (9.9%) of the 91 patients had complications associated with laparoscopic procedures and 4 (4.4%) of them had major complications. Pneumoextraperitoneum occurred in 3 patients. Two patients, who suffered from preperitoneal insufflation or pneumothorax associated with pneumomediastinum, failed to undergo laparoscopy. A small amount of scrotal emphysema developed in one patient, which subsided within 12 hours. Another patient, who underwent radical nephrectomy and para-aortic lymphadenectomy for left renal cell carcinoma, complained of symptoms due to persistent pneumoperitoneum and subcutaneous emphysema, which subsided 2 weeks after the operation. Respiratory acidosis caused by carbon dioxide absorption, which was difficult to be controlled, occurred in the other two patients; one was an adult male with reduced respiratory function and the other was a 1-year-and-8-month-old child. Bleeding during or after the procedure was another serious complication. Vena caval laceration occurred during right simple nephrectomy for pyonephrosis with renal calculi and was managed with laparotomy. Two patients, one after simple nephrectomy and the other after right adrenalectomy, suffered from postoperative bleeding about 300 ml through the penrose drain, which subsided following a bed rest.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Differential regulation of Na+/H+ exchange and H(+)-ATPase by pH and HCO3- in kidney proximal tubules.

This study examines the effects of acute in vitro acid-base disorders on Na+/H+ and H(+)-ATPase transporters in rabbit kidney proximal tubules (PT). PT suspensions were incubated in solutions with varying acid base conditions for 45 min and utilized for brush border membrane (BBM) vesicles preparation. BBM vesicles were studied for Na+/H+ exchange activity (assayed by 22Na+ influx) or abundance (using NHE-3 specific antibody) and H(+)-ATPase transporter abundance (using antibody against the 31 kDa subunit). The Na+/H+ exchanger activity increased by 55% in metabolic acidosis (pH 6.5, HCO3- 3 mM) and decreased by 41% in metabolic alkalosis (pH 8.0, HCO3- 90 mM). The abundance of NHE-3 remained constant in acidic, control, and alkalotic groups. H(+)-ATPase abundance, however, decreased in metabolic acidosis and increased in metabolic alkalosis by 57% and 42%, respectively. In PT suspensions incubated in isohydric conditions (pH 7.4), Na+/H+ exchanger activity increased by 29% in high HCO3- group (HCO3- 96 mM) and decreased by 16% in the low HCO3- groups (HCO3- 7 mM. The NHE-3 abundance remained constant in high, normal, and low [HCO3-] tubules. The abundance of H(+)-ATPase, however, increased by 82% in high [HCO3-] and decreased by 77% in the low [HCO3-] tubules. In PT suspensions incubated in varying pCO2 and constant [HCO3-], Na+/H+ exchanger activity increased by 35% in high pCO2 (20% pCO2, respiratory acidosis) and decreased by 32% in low pCO2 (1.5% pCO2, respiratory alkalosis) tubules. The NHE-3 abundance remained unchanged in high, normal, and low pCO2 tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1996

Lung volume measurements immediately after extubation by prediction of "extubation failure" in premature infants.

To test the hypothesis that premature infants in whom extubation fails in the first 10 days of life have low volume lungs, functional residual capacity (FRC) was measured in the first hour after extubation. Once extubated, infants received the appropriate level of inspired oxygen necessary to maintain acceptable arterial oxygen saturation. After humidification, oxygen was bled into a headbox, and FRC was assessed using a helium gas dilution technique and a specially designed infant circuit. The results were related to extubation failure, which was diagnosed when the infant required nasal continuous positive airway pressure or re-intubation and ventilation within 48 hours. The latter two forms of respiratory support were instituted by the clinical team, whenever the infant developed recurrent or severe apnea or respiratory acidosis. Infants were eligible for entry into the study when born prematurely and extubated within the first 10 days of life. Twenty infants initially ventilated for respiratory distress syndrome at a median gestational age of 29 weeks (range, 26-36 weeks) were studied at a median postnatal age of 3 days (range, 1-7 days). All were receiving theophylline. Extubation failed in seven infants, who did not differ significantly from the rest of the cohort regarding gestational age, birthweight, postnatal age, or inspired oxygen concentration (F(I)O2) at extubation, but their maximum F(I)O2 during ventilation was higher than in those infants who did not require reintubation (P < 0.05). In the infants who failed extubation, the median FRC was 19 ml/kg (range, 12-27 ml/kg), which was lower than that of the infants in whom extubation was successfully accomplished (median, 28 ml/kg; range, 19-37 ml/kg; P < 0.01). An FRC of less than 26 ml/kg had a sensitivity of 71% and specificity of 77% in predicting extubation failure. These results support the hypothesis that a very low lung volume relates to extubation failure in the first 10 days of life.

Female↗
PubMed2004

Dexmedetomidine pharmacodynamics: part I: crossover comparison of the respiratory effects of dexmedetomidine and remifentanil in healthy volunteers.

BACKGROUND: Dexmedetomidine, a highly selective alpha2-adrenoceptor agonist used for short-term sedation of mechanically ventilated patients, has minimal effect on ventilation. METHODS: This study compared the respiratory effect of dexmedetomidine to that of remifentanil. The authors measured and compared respiratory responses of six healthy male volunteers during (1) a stepwise target-controlled infusion of remifentanil, (2) a stepwise target-controlled infusion of dexmedetomidine, and (3) a pseudonatural sleep session. RESULTS: Compared with baseline, remifentanil infusions resulted in respiratory depression as evidenced by a decrease in respiratory rate and minute ventilation, respiratory acidosis, and apnea episodes resulting in desaturations. Remifentanil disturbed the natural pattern of breathing and flattened the distribution of ventilatory timing (inspiratory time/ventilatory cycle time). The respiratory effects of dexmedetomidine markedly contrasted with those of remifentanil. When compared with baseline, during dexmedetomidine infusions, the respiratory rate significantly increased, and the overall apnea/hypopnea index significantly decreased. The distribution of inspiratory time/ventilatory cycle time showed an increased peak. In addition, dexmedetomidine seemed to mimic some aspect of natural sleep. While the subjects were breathing a 5% CO2 mixture, hypercapnic arousal phenomena (documented by the Bispectral Index, the electroencephalogram, and sudden increase in the minute ventilation) were observed during dexmedetomidine infusions. Similar phenomena during natural sleep have been reported in the literature. CONCLUSIONS: In comparison with remifentanil, dexmedetomidine infusions (1) did not result in clinically significant respiratory depression, (2) decreased rather than increased the apnea/hypopnea index, and (3) exhibited some similarity with natural sleep.

Adult↗
PubMed1982

Proximal reabsorption during metabolic acidosis in the rat.

The mechanism by which proximal volume reabsorption is reduced during hyperchloremic metabolic acidosis was studied using free-flow micropuncture techniques in Munich-Wistar rats. Compared with control hydropenic conditions, absolute rates of proximal total CO2 and water reabsorption rates during NH4Cl-induced metabolic acidosis were diminished: from 557 +/- 35 to 204 +/- 19 pmol/min and from 13.0 +/- 1.0 to 9.7 +/- 0.6 nl/min, respectively. Inhibition of proximal volume reabsorption during metabolic acidosis was not attributable to alterations in the reabsorptive Starling forces, since peritubular capillary oncotic and hydraulic pressures were normal, or to acidemia itself, since acute respiratory acidosis was not found to decrease reabsorption. When partial repair of the acidosis was achieved by NaHCO3 infusion, absolute reabsorption of both total CO2 (390 +/- 48 pmol/min) and water (12.2 +/- 1.1 nl/min) significantly increased despite modest extracellular volume expansion. NaCl infusion in acidotic animals had no restorative effect on volume reabsorption. Mean values for single nephron glomerular filtration rate were similar under all conditions. Absolute chloride reabsorption tended to correlate better with absolute bicarbonate reabsorption and, hence, with the magnitude of the chloride concentration gradient developed than with the filtered chloride load. In conclusion, absolute proximal volume reabsorption during metabolic acidosis and its partial repair correlated with the absolute magnitude of bicarbonate filtered and reabsorbed. It is proposed that proximal volume reabsorption may be regulated, at least in part, by the anion composition of the glomerular ultrafiltrate.

Absorption↗
PubMed2001

Acid-base status and blood gas arterial values in free-ranging sika deer hinds immobilized with medetomidine and ketamine.

Ten free-ranging female sika deer (Cervus nippon) were captured to obtain the reference values for acid-base status and blood gas when immobilized with the combination of medetomidine and ketamine. The mean +/- SE of PaCO2, PaO2, and HCO3- were 58.1 +/- 6.1 mmHg, 58.8 +/- 6.4 mmHg, and 36.0 +/- 4.4 mmol/l, respectively. Although acidosis and alkalosis occurred in three and two animals, respectively, no serious conditions were observed. The blood values, however, suggest that some degree of hypoxemia and respiratory acidosis with metabolic alkalosis are developed. The trapped deer showed a significantly higher than normal rectal temperature reflective of exertion.

Acid-Base Equilibrium↗
PubMedDate not supplied

[Bochdalek's congenital diaphragmatic hernia: a clinical review of 114 cases].

During a retrospective multicentric study of the encountered congenital pathology of the diaphragmatic domes, we focused our special attention on the prevalence of the congenital Bochdalek hernia. 140 charts were statistically analysed. The seriousness of the medical and surgical emergency situation enticed the authors to examine the most important prognostic clinical features. The interval between diagnosis and surgical therapy should be as short as possible. Respiratory acidosis and resuscitation were a common denomination in all infants who succumbed in the post-operative period. The early occurrence (less than 6 hrs) of respiratory distress disclosed the seriousness of the associated pulmonary hypoplasia. Surgical technical problems were rare. This in contrast to the struggle against pulmonary arterial and capillary hypertension. Pulmonary vasodilator drugs have not convinced those who initiated their use.

Diaphragm↗