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At least 1,297 records · Page 72Linked to original sources
PubMed1995

Immunolocalization of proton pumps (H+-ATPase) in pavement cells of rainbow trout gill

The expression of the V-type proton ATPase (H+-ATPase) was examined in the gill of the freshwater rainbow trout (Oncorhynchus mykiss) using immunocytochemistry in concert with laser scanning confocal or electron microscopy. A synthetic peptide consisting of the carboxy-terminal region of the 31 kDa subunit of the bovine renal H+-ATPase was used to generate an antiserum in rabbits, and its suitability for use in trout gill was confirmed by western blotting. Gill epithelial cells demonstrated specific immunoreactivity, the intensity of which was increased markedly after 18 h of exposure to hypercapnia (1 % CO2 in air). The increased intensity of H+-ATPase immunoreactivity was associated with elevated branchial net acid excretion. In the hypercapnic fish, the specific immunoreactivity was associated with both the apical membrane and cytoplasm. Electron microscopy revealed that specific immunoreactivity was localized to the pavement cells and was particularly associated with the apical membrane and subapical cytoplasmic vesicles. The increased H+-ATPase immunoreactivity in the epithelial cells of hypercapnic fish and the increased intensity of the immunoreactive bands in western blots from hypercapnic fish demonstrate an 'up-regulation' of this protein in response to respiratory acidosis. The results are discussed with reference to current models of acid­base and ion regulation in the gill of freshwater fish.

Journal Article↗
PubMed1996

Relative effects of carbonic anhydrase infusion or inhibition on carbon dioxide transport and acid-base status in the sea lamprey Petromyzon marinus following exercise

In vivo experiments were carried out to determine the relative effects of carbonic anhydrase (CA) infusion or inhibition on carbon dioxide (CO2) transport and acid-base status in the arterial and venous blood of sea lampreys recovering from exhaustive exercise. Infusion of CA into the extracellular fluid did not significantly affect CO2 transport or acid-base status in exercised lampreys. In contrast, infusion of the CA inhibitor acetazolamide resulted in a respiratory acidosis in the blood of recovering lampreys. In acetazolamide-treated lampreys, the post-exercise extracellular pH (pHe) of arterial blood was significantly lower than that in the saline-infused (control) lampreys. The calculated arterial and venous partial pressure of carbon dioxide (PCO2) and the total CO2 concentration in whole blood (CCO2wb) and red blood cells (CCO2rbc) during recovery in the acetazolamide-infused lampreys were also significantly greater than those values in the saline-infused control lampreys. These results suggest that the CO2 reactions in the extracellular compartment of lampreys may already be in equilibrium and that the access of plasma bicarbonate to CA is probably not the sole factor limiting CO2 transport in these animals. Furthermore, endogenous red blood cell CA clearly has an important role in CO2 transport in exercising lampreys.

Journal Article↗
PubMed1976

The mobilization of calcium and bicarbonate by raised concentrations of potassium in the haemolymph of the snail, Helix pomatia.

1. After the concentration of potassium in the haemolymph of Helix pomatia has been raised by the infusion of KCl, it falls approximately exponentially for a time and then tends to rise. The accompanying rise and fall of calcium concentration can be fitted to a simple mathematical model. 2. The mobilization of calcium is accompanied by the generation of bicarbonate in equivalent amounts, without much change in pH or Pco2. 3. There is probably an increased production or retention of carbon dioxide at this time, but the main cause of the changes in calcium and bicarbonate is not respiratory acidosis. 4. The concentration of potassium rises in snalis that have been infused with CaCl2. 5. The adverse responses visible in snails infused with KCl are largely prevented when CaCl2 is infused at the same time. 6. Homeostasis seems to involve the maintenance of a proper balance of calcium and potassium concentrations.

Animals↗
PubMed1979

Acid-base relationships in the blood of the toad, Bufo marinus. I. The effects of environmental CO2.

An abrupt increase in ambient CO2 resulted in a marked respiratory acidosis which took place within 30 min. During this time there was a considerable reduction in the PCO2 difference between arterial blood and inspired gas caused by an increase in ventilations. Prolonged CO2 exposure (24 h) showed that there was some compensation for the acidosis in that plasma bicarbonate concentrations increased substantially. At the same time, however, the PCO2 of arterial blood always rose so that the net result was usually only a small increase in pH. Upon return to air, the blood was backtitrated along a buffer line elevated above and parallel to that seen during the initial response to hypercapnia. The fall in arterial blood PCO2 during the early stages of recovery often led to pH values higher than those seen in the untreated animal. After 48 h in air, recovery had gone further with PCO2, pH and [HCO3-] levels approaching but rarely reaching the pre-exposure values.

Acid-Base Equilibrium↗
PubMed1979

Acid-base relationships in the blood of the toad, Bufo marinus. II. The effects of dehydration.

Cutaneous CO2 excretion is reduced as the skin dries during dehydration but an increase in breath frequency acts to regulate the arterial blood PCO2 and thus pHa. Moreover, the toad does not urinate and water is reabsorbed from the bladder to replace that lost by evaporation at the skin and lung surfaces. The animal does, however, produce a very acid bladder urine to conserve circulating levels of plasma [HCO3-] and this together with an increased ventilation effectively maintains the blood acid-base status for up to 48 h of dehydration in air. Water loss and acid production are presumably also reduced by the animal's behaviour; animals remain still, in a crouched position or in a pile if left in groups. Dehydrated toads are less able than hydrated toads to regulate blood pH during hypercapnia: they hyperventilate and mobilize body bicarbonate stores in much the same fashion as hydrated animals but due to the restrictions on cutaneous CO2 excretion and renal output, there is comparatively little reduction in the PCO2 difference between arterial blood and inspired gas thereby resulting in a more severe respiratory acidosis. These factors further contribute to the persistent acidosis which continues even when the animals are returned to air.

Acid-Base Equilibrium↗
PubMed1979

Acid-base relationships in the blood of the toad, Bufo marinus. III. The effects of burrowing.

When Bufo marinus burrows, the skin becomes intimately surrounded by substrate but the nares always remain exposed to the surface air. Upon entering into a state of dormancy the animal hypoventilates and this together with the loss of the skin as a respiratory site results in a rise in arterial blood PCO2 despite a probable decline in metabolism. Even though lung ventilation falls, the toad regulates blood pH and the respiratory acidosis is progressively compensated for by a progressive increase in plasma [HCO3-] along the course of an elevated PCO2 isopleth. At steady state, the acidosis is fully compensated for by a new equilibrium ratio of HCO3- to PCO2 at the same pH as the non-burrowed animal. Arousal from the dormant state at this time results in a marked lung hyperventilation and a sharp decline in body CO2 stores.

Acid-Base Equilibrium↗
PubMed1985

The influence of renal sympathetic nerves on renal hemodynamic and renin responses during hypercapnia in dogs.

Studies were conducted in anesthetized dogs to examine the influence of the renal sympathetic nerves on renal hemodynamic and renin responses during controlled hypercapnia. The dogs were subjected to unilateral denervation and tested for their responses to hypercapnia induced by inhalation of 15% CO2 in air. Simultaneous measurements of the responses from both the denervated and innervated kidneys allowed an assessment of the influence of the renal nerves on the responses during acute hypercapnia. The data indicate that reductions in renal blood flow and glomerular filtration rate and increases in renin of the renal vein during respiratory acidosis are dependent, in part, on the presence of intact renal nerves. Other factors, however, are probably also present.

Animals↗
PubMed1989

[Study of umbilical cord coiling and variable deceleration].

Using cardiotocogram and umbilical arterial gas analysis, the presence or absence and variations of umbilical cord coiling were examined with relation to the incidence of variable deceleration (V.D.) and neonatal asphyxia. The results obtained were as follows. 1) The incidence of V.D. with cord coiling was higher than that without cord coiling (p less than 0.005). The incidence of severe V.D. with cord coiling was also higher than that without cord coiling (p less than 0.005). 2) The mean Apgar scores of cases with cord coiling were lower than that without cord coiling (p less than 0.02). 3) On the umbilical arterial gas analysis, the mean pH of cases with cord coiling was lower than that without cord coiling (p less than 0.05). And the mean pCO2 of cases with cord coiling was higher than that without cord coiling (p less than 0.005). So neonate with cord coiling showed a tendency towards respiratory acidosis in comparison with that without cord coiling. 4) The incidence of neonatal asphyxia with cord coiling was 16.0% (Apgar score less than or equal to 7), 20.0% (pH less than 7.20) and that without cord coiling was 8.8%, 13.2%, respectively. Although there was no statistically significant difference, a tendency was observed towards a higher rate of neonatal asphyxia with cord coiling. 5) The incidence of neonatal asphyxia with severe V.D. was 44.4% (Apgar score less than or equal to 7), 36.1% (pH less than 7.20) and that without severe V.D. was 5.7%, 8.6%, respectively. There was a statistically significant difference (p less than 0.005, p less than 0.005). In addition, the incidence of neonatal asphyxia with repeated V.D. was 35.3% (Apgar score less than or equal to 7), 44.1% (pH less than 7.20) and without repeated V.D. was 3.8%, 6.5%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Asphyxia Neonatorum↗
PubMed1987

Necrotizing tracheobronchitis: a newly recognized cause of acute obstruction in mechanically ventilated neonates.

Necrotizing tracheobronchitis (NTB) is an acute inflammatory lesion of the lower airway which can result in total airway obstruction. While potentially treatable, this lesion has been described predominantly in autopsy or animal studies. We observed clinical symptoms which reflect development of this lesion. Symptoms of acute airway obstruction (hypercarbia, respiratory acidosis, decreased chest wall movement) occurred in eight neonates undergoing treatment with high-frequency jet ventilation; five patients treated with HFJV were studied without signs of obstruction. Emergency bronchoscopy using a rigid bronchoscope was performed in the intensive care unit. The diagnosis of NTB was made by the observation of hyperemia, intraluminal debris, or the appearance of eschar formation. Necrotic debris was removed using forceps and/or suction as necessary. All patients survived treatment. Seven were long-term survivors, all with bronchopulmonary dysplasia. In patients who died, autopsy evaluation of the airway revealed a characteristic picture consisting of necrosis, neutrophil infiltration, epithelial erosion, and intraluminal obstruction.

Airway Obstruction↗
PubMed1994

Laryngeal microsurgery under general anesthesia using small-bore endotracheal tubes: blood gas analysis.

This study reports variations observed under general anesthesia through small-bore endotracheal tubes in PO2, PCO2, HCO3, percentage saturation of O2, and pH levels in 39 patients who underwent laryngeal microsurgery lasting from 10 to 100 minutes. The tendency to an increase in PCO2 levels reached statistical significance only at the 100th minute but did not constitute a risk for patients as values remained within the limits of "permitted hypercapnia." PO2, percentage saturation of oxygen, and HCO3 levels did not vary significantly. pH values tended to fall (respiratory acidosis) in correlation to the increase in PCO2. Small-bore endotracheal tubes can safely be used for laryngeal microsurgery when operating times are not longer than 100 minutes.

Anesthesia, General↗
PubMed1994

Sevoflurane anesthesia following administration of atropine-guaifenesin-thiopental in spontaneous-breathing adult cattle.

The effect of sevoflurane-oxygen anesthesia at surgical depth on clinically important features was evaluated in spontaneously breathing cattle given atropine-guaifenesin-thiopental. The mean end-tidal sevoflurane concentrations ranged from 1.4 to 2.0% for 75 min maintenance. Recovery from anesthesia was extremely rapid and smooth. Heart rate increased and arterial pressure was higher during anesthesia, but respiratory rate did not change significantly. Arrhythmia was not observed. Minute ventilation was low due to decreased tidal volume during anesthesia, and changes in blood gases and pH showed mild respiratory acidosis. There were no marked changes in hematologic or serum biochemical values for 7 days postanesthesia. These findings suggest that sevoflurane is an effective inhalant anesthetic showing rapid recovery from anesthesia.

Anesthesia, General↗
PubMed2003

Tracheal gas isufflation-aided mechanical ventilation during carbon dioxide-induced pneumoperitoneum in rabbits.

Despite numerous benefits of laparoscopic procedures, the serious hypercapnia and respiratory acidosis in hypercapnic patients with decreased pulmonary compliance during carbon dioxide-induced pneumoperitoneum (CDP) may be developed. Tracheal gas insufflation (TGI) has been shown to be a useful adjunct to controlled mechanical hypoventilation. This study was undertaken to identify whether TGI superimposed on controlled mechanical ventilation (CMV) improve ventilatory efficiency during CDP in rabbits. Sixteen paralyzed and anesthetized rabbits were used. The animals were assigned to two groups-CMV group: CMV alone; TGI group: CMV superimposed by TGI with flow rate of 2L/min. The animals were insufflated to intra-abdominal pressure of 8 mmHg with CO2 gas. Then, tidal volume (V(T)) was changed to maintain the set peak inspiratory pressure (PIP) value, while other ventilatory settings were kept constant. The set PIP value corresponding to 30, 60, and 90 min after the start of peritoneal insufflation of CO2 were 15, 22, and 25 cm H2O, respectively. During CDP with TGI, PaCO2 decreased significantly (p<0.01) from CMV without TGI of 82.1 +/- 14.1 to 47.5 +/- 5.5, 58.1 +/- 9.9 to 40.0 +/- 4.6, 47.1 +/- 9.4 to 32.7 +/- 5.1 mmHg at PIP of 15, 22, and 25 cm H2O, respectively. The inspired V(T) decreased significantly (p<0.05) from CMV without TGI of 18.4 +/- 3.9 to 12.8 +/- 2.8 ml at PIP of 15 cm H2O. TGI superimposed on CMV is more effective than CMV alone in enhancing ventilatory efficiency during CDP in rabbits.

Animals↗
PubMed2003

Nesiritide treatment of noncardiogenic pulmonary edema.

OBJECTIVE: To report the efficacy of nesiritide in treating noncardiogenic pulmonary edema. CASE SUMMARY: A 50-year-old African American woman with a complex medical history including morbid obesity, acute bronchitis, obstructive sleep apnea, hypertension, and numerous hospitalizations for volume overload presented to the emergency department with severe dyspnea. A portable chest X-ray displayed perihilar congestion and bilateral pulmonary edema. An echocardiogram demonstrated normal left-ventricular systolic and diastolic function. She was aggressively treated with nitrates, diuretics, bronchodilators, and oxygen. Despite these efforts, the patient's arterial blood gas (ABG) continued to show respiratory acidosis, the oxygen saturation was significantly depressed, and the dyspnea continued. Since standard therapies were failing after 12 hours, the patient was treated with intravenous nesiritide. The results were profound in terms of rapid symptomatic and prognostic improvement (i.e., ABG) beginning within 45 minutes of administration, and the patient was discharged after a 5-day hospital course. DISCUSSION: Nesiritide is a human B-type natriuretic peptide that has been shown to improve hemodynamic function and symptoms associated with decompensated heart failure. This is primarily due to the actions of this medication, including diuresis, decreased mean arterial pressure, and improvement of pulmonary arterial occlusion pressure as determined by published clinical trial outcomes. This case describes the use of nesiritide as an effective adjunctive therapy in treating a patient with noncardiogenic pulmonary edema. CONCLUSIONS: Nesiritide appears to be an efficacious treatment for acute pulmonary edema, resistant to standard-of-care therapies, in the presence of normal left-ventricular function.

Blood Gas Analysis↗
PubMed1993

Life-threatening asthma with dramatic resolution.

The speed of onset of an asthma attack can be highly variable. Recent studies have tried to characterize a subgroup of patients with life-threatening asthma that occurs suddenly but often regresses very rapidly under treatment. We had the opportunity to observe the evolution of two asthmatic women hospitalized with extremely severe respiratory acidosis. One of them required immediate orotracheal intubation and mechanical ventilation during 13 h. The results of her pulmonary function tests were normal 35 h after admission. The second woman's condition improved so rapidly under treatment that she did not require intubation and mechanical ventilation. These observations suggest that bronchospasm might play an important role in the pathophysiology of transient life-threatening asthma.

Acute Disease↗
PubMed2000

Negative pressure ventilation vs external high-frequency oscillation during rigid bronchoscopy. A controlled randomized trial.

STUDY OBJECTIVES: To compare the effectiveness of two modalities of external ventilation during rigid bronchoscopy: intermittent negative pressure ventilation (INPV) and external high-frequency oscillation (EHFO). DESIGN: Prospective, controlled, randomized, nonblinded study. SETTING: University-affiliated hospital. PATIENTS: Seventy patients undergoing interventional rigid bronchoscopy for tracheobronchial lesions were enrolled into the study. INTERVENTIONS: Mechanical ventilation was performed by INPV or EHFO. When pulse oximetry was < 90%, manually assisted ventilation was delivered. MEASUREMENTS AND RESULTS: Arterial blood gases were sampled preoperatively and intraoperatively. Most patients in both groups had normal intraoperative PaCO(2) (mean, 43. 6 +/- 11.8 mm Hg under EHFO and 37.4 +/- 8.2 mm Hg under INPV; p = 0.012), and acidemia occurred in 9 of 35 patients of EHFO group and in 2 of 35 patients of INPV group (p = 0.049). Hypercapnia (PaCO(2) > 50 mm Hg) was observed in 10 patients under EHFO and in 2 with INPV (p = 0.026). Intraoperative mean PaO(2) was similar (101.4 +/- 52.9 mm Hg with EHFO and 124.2 +/- 50.3 mm Hg with INPV; p = 0.07), but O(2) supply was different (3.5 +/- 2.3 L/min during INPV and 8.5 +/- 6.2 L/min during EHFO; p < 0.001). Intraoperative hypoxemia (PaO(2) < 60 mm Hg) occurred in five patients with EHFO and two with INPV (p = 0.426). Three EHFO patients required manually assisted ventilation (mean, 0.2 +/- 0.9), but no INPV patient did (p = 0.142). CONCLUSIONS: External negative pressure ventilation appears to be a suitable choice during rigid bronchoscopy: both EHFO and INPV ensure effective ventilation and comfortable operating conditions in the majority of patients. Some patients may receive inadequate ventilation with EHFO, developing respiratory acidosis and requiring manually assisted ventilation. In comparison with INPV, EHFO requires a higher fraction of inspired oxygen.

Adult↗
PubMed1986

Acute oxygen in patients with sleep apnea and COPD.

Nocturnal oxygen administered to patients with disordered breathing ameliorates hypoxemia. As a result, an important chemical stimulus to arousal is diminished. This could cause prolongation of disordered breathing events, worsen respiratory acidosis, and induce potentially harmful cardiac arrhythmias. The presence of chronic obstructive pulmonary disease (COPD) could further aggravate the situation since such patients may have depressed hypercarbic responses. To test this hypothesis, 20 obese men with sleep apnea and COPD were studied polysomnographically on two nights receiving air on one or oxygen at 4 L/min on the other. Supplemental oxygen increased mean DOB event duration from 25.7 to 31.4 seconds (p less than 0.001), increased end apneic PCO2 from 52.8 to 62.3 mm Hg (p less than 0.025), and decreased mean end apneic pH from 7.34 to 7.28 (p less than 0.001). At the same time, it improved mean sleeping and end-apneic oxygen saturation. The number of ventricular extra-systoles (PVCs) per minute of sleep showed small increases in three subjects while breathing oxygen. Complex ventricular arrhythmias were unaffected by oxygen in five subjects. Oxygen eliminated atrioventricular block in two subjects. We conclude that nocturnal supplemental oxygen does not increase ventricular arrhythmias in the majority of patients with COPD and coexisting disordered breathing events. While the clinical significance of an oxygen associated increase in ventricular extrasystoles in three subjects is unclear, nocturnal monitoring by telemetry or ambulatory recorder should be sufficient to detect such patients.

Adult↗
PubMed1988

Cardiovascular effects of conventional positive pressure ventilation and airway pressure release ventilation.

The hemodynamic sequelae of conventional positive pressure ventilation (CPPV), airway pressure release ventilation (APRV), and spontaneous breathing were compared with continuous positive airway pressure (CPAP) in ten anesthetized dogs who had ventilatory failure with and without parenchymal lung injury. The APRV corrected respiratory acidosis without significantly effecting arterial blood oxygenation, venous admixture, cardiovascular function, or tissue oxygen utilization. Application of CPPV precipitated marked depressions in blood pressure, stroke volume, and cardiac output. A concomitant decrease in venous admixture did not compensate for these adverse cardiovascular effects. Deterioration of tissue oxygen delivery resulted in oxygen supply-demand imbalance during CPPV. The results of this experimental study indicate that if ventilatory augmentation of subjects who require CPAP is desired, APRV will enhance alveolar ventilation without compromising circulatory function and tissue oxygen balance, whereas CPPV will impair cardiovascular function significantly.

Animals↗
PubMed1989

Pulmonary vascular resistance before and after cardiopulmonary bypass. The effect of PaCO2.

To examine whether CPB influences pulmonary vascular sensitivity to CO2, we compared the effect of slight induced hypocarbia and hypercarbia on pulmonary circulation before and after CPB in ten mechanically ventilated patients undergoing CABG. Hypocarbia was produced by increasing tidal volume slightly and hypercarbia was then induced by adding CO2 to the inspired gas mixture. In another ten patients, hypercarbia was produced after CPB by decreasing ventilator rate and the cardiopulmonary responses to hypercarbia, produced by the two methods of CO2 elevation, were compared. Slight respiratory acidosis induced by CO2 inhalation did not change PVR before CPB but effected a 50 percent increase after CPB. Hypercarbia induced by alveolar hypoventilation after CPB increased PVR by 40 percent. During the increased CO2 production after hypothermic CPB, pulmonary vasoconstriction would be expected to occur and impair right ventricular performance. Therefore, tight control of PaCO2 with appropriate adjustment of ventilatory support is mandatory.

Carbon Dioxide↗