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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypercarbia occurs during laparoscopy with carbon dioxide (CO2) insufflation. This may be due to increased ventilatory dead space after expansion of the peritoneal cavity with impairment of diaphragmatic excursion, or to increased absorption of CO2 from the peritoneum. To separate these effects, the authors examined the consequences of different insufflating gases and of diminished tissue perfusion on hypercarbia and dead space during pneumoperitoneum. Helium was chosen as an alternate insufflating gas because it is both inert and minimally absorbed. Eight swine (18 to 20 kg) were anesthetized, paralyzed, and mechanically ventilated at constant minute volume. Pneumoperitoneum with helium was maintained at 15 mm Hg for 45 minutes. After desufflation and stabilization for 1 hour, pneumoperitoneum was repeated with CO2. The sequence was again repeated after hemorrhagic shock to constant mean arterial pressure of 50 mm Hg. Data was analyzed by analysis of variance; significance levels are P < 0.01 unless otherwise listed. Arterial PCO2 increased significantly with CO2 insufflation within 15 minutes in normotensive animals and within 30 minutes during hypotension. Arterial pH decrease with CO2 pneumoperitoneum was significant in both groups at 30 minutes. Mixed venous PCO2 also increased with CO2 pneumoperitoneum within 30 minutes. Hypotension did not alter these changes. No significant changes were seen with helium pneumoperitoneum. Neither helium nor CO2 pneumoperitoneum significantly altered dead space. The authors make the following conclusions: 1) Absorption of CO2 from the abdomen during CO2 pneumoperitoneum produces respiratory acidosis, which is not seen with helium insufflation; 2) Pneumoperitoneum does not significantly increase dead space with either gas; 3) Transperitoneal absorption of CO2 is only partly related to perfusion because significant hypercarbia occurs during hemorrhagic shock.
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PMID:Effectors of hypercarbia during experimental pneumoperitoneum. 145 92

Laparoscopic cholecystectomy with carbon dioxide pneumoperitoneum may result in hypercarbia and acidosis in patients with cardiorespiratory disease. The aim of the present study was to assess helium as an alternative to carbon dioxide for creating the pneumoperitoneum. Ventilation requirements and carbon dioxide levels were assessed at the beginning and end of laparoscopic cholecystectomy using helium (n = 30) and carbon dioxide (n = 30) pneumoperitoneum. Insufflation with helium did not result in an increase in ventilation requirement although, like carbon dioxide pneumoperitoneum, it was associated with a mean rise in peak airway pressure (of 7 cmH2O; P < 0.001). There was also a 3.2-kPa increase in the alveolar-arterial oxygen gradient with helium (P = 0.006). Carbon dioxide pneumoperitoneum was associated with a significant rise in arterial carbon dioxide levels, despite increasing ventilation. Four patients with helium pneumoperitoneum had surgical emphysema for 5 days. Helium may be a suitable alternative to carbon dioxide for creating pneumoperitoneum in patients with severe cardiorespiratory disease. However, because of its low water solubility helium has a lower safety margin than carbon dioxide in the rare event of gas embolism.
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PMID:Helium pneumoperitoneum for laparoscopic cholecystectomy: ventilatory and blood gas changes. 792 57

The recent surge in enthusiasm for laparoscopic surgery has created concern that abdominal insufflation with carbon dioxide produces a respiratory acidosis. This may be because of both transperitoneal gas absorption and impaired ventilation with increased dead space from elevated intraabdominal pressure. To examine the relative contributions of these factors, we developed an animal model of surgical pneumoperitoneum that evaluated the cardiorespiratory effects of abdominal insufflation. Helium was chosen as an alternative to CO2 because it is both chemically and biologically inert. Carbon dioxide absorption during CO2 pneumoperitoneum caused arterial PCO2 to increase from 41.3 +/- 3.0 to a maximum of 58.3 +/- 4.0 mm Hg, with pH descending from 7.46 +/- 0.02 to a nadir of 7.31 +/- 0.02 (p < 0.05). Pulmonary artery pressure increased to twice baseline levels during CO2 insufflation (p < 0.05). Helium did not cause hypercarbia, acidemia, or pulmonary hypertension despite insufflation under identical conditions. These results indicate that transperitoneal absorption of CO2, not increased dead space, is responsible for the respiratory acidosis observed. Helium merits further study as an agent to induce pneumoperitoneum, especially when concerns of underlying acidosis or impaired gas exchange are present.
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PMID:Comparative cardiopulmonary effects of carbon dioxide versus helium pneumoperitoneum. 848 70

Abdominal CO2 insufflation has been shown to cause hypercarbia, acidemia, and decreased oxygenation in a pediatric animal model. Such metabolic derangements have prompted a search for alternative insufflation gases. This study compares the hemodynamic and ventilatory changes that occur during pneumoperitoneum with CO2 and helium. Four juvenile swine were intubated and given general anesthesia. Minute ventilation was adjusted to obtain a baseline Pco2 of between 32 and 36 mm Hg, and was kept constant for the duration of the experiment. The subjects initially were insufflated with CO2 or helium at a pressure of 10 mm Hg. Peak ventilatory pressure, end-tidal CO2 (ETCO2) arterial pH, Pco2, Po2, and right atrial and inferior vena caval pressures were measured before and during a 1-hour insufflation period. After desufflation, Pco2 and pH were restabilized. The same parameters were then measured during reinsufflation with the alternate gas. CO2 insufflation caused significant decreases in pH, from 7.51 +/- 0.03 to 7.32 +/- 0.06, and Po2 increased from 261 +/- 49 to 189 +/- 33 mm Hg. Pco2 increased from 35.0 +/- 1.4 to 57.9 +/- 6.3 mm Hg. ETCO2 also increased, from 29.0 +/- 2.2 to 47.2 +/- 5.0 mm Hg. Helium insufflation caused pH to decrease from 7.51 +/- 0.01 to 7.42 +/- 0.04. Pco2 increased from 32.8 +/- 0.8 to 43.5 +/- 3.9 mm Hg, and ETCO2 increased from 27.8 +/- 0.5 to 36.8 +/- 3.1 mm Hg. These alterations were significantly less than those with CO2 pneumoperitoneum. Po2 decreased as well-from 266 +/- 30 to 212 +/- 21 mm Hg. During insufflation with both gases, peak ventilatory pressure and right atrial pressure increased significantly. Abdominal insufflation with CO2 or helium causes hypercarbia, acidemia, and increased ETCO2 in this juvenile animal model. These derangements are significantly less with helium. This gas may prove to be the more suitable insufflation agent for pediatric patients.
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PMID:A comparison of the hemodynamic and ventilatory effects of abdominal insufflation with helium and carbon dioxide in young swine. 893 64

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.
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PMID:Helium and carbon dioxide pneumoperitoneum in patients with pheochromocytoma undergoing laparoscopic adrenalectomy. 984 53

Since 1934 several clinical trials have been performed to investigate the effect of helium in the symptomatic treatment of upper and lower airway obstructions, especially in children. Controlled studies have only been produced during the last decade. Heliox, a mixture of helium and oxygen, has a significantly lower density than N2/O2-mixtures. This produces better flow and hence a decrease in respiratory work, improvement of distal gas exchange and theoretically less tendency to air-trapping and hyperinflation. When holding more than 40% O2 the clinical effect decreases. There are case reports of rapid subjective release, less stridor, lower respiratory rate and a normalization of hypercapnia and acidosis. Controlled studies confirm this and demonstrate a decrease in the need for intubation and mechanical ventilation. Time is bought until conventional therapy with steroids, epinephrine and beta 2-agonist inhalation works. Helium has its place in treatment of airway obstructions, but more clinical trials are needed to define the indication for symptomatic heliox treatment.
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PMID:[Symptomatic helium treatment of upper and lower airway obstruction]. 1118 52

Helium is a low-density inert gas whose physical properties are very different from those of nitrogen and oxygen. Such properties could be clinically useful in the adult critical care setting, especially in patients with upper to more distal airway obstruction requiring moderate to intermediate levels of FiO2. However, despite decades of utilization and reporting, it is still difficult to give any firm clinical recommendation in this setting. Numerous case reports are available in the context of upper airway obstruction of different origins, but there is a lack of controlled studies for this indication. One study reported a helium-induced beneficial effect on surrogates of work of breathing after extubation in non-COPD patients, possibly in relation to laryngeal consequences of tracheal intubation. Physiological benefits of helium-oxygen breathing have been demonstrated in the context of acute severe asthma, but there is a lack of large controlled studies demonstrating an effect on pertinent clinical endpoints, except for a study reported only as an abstract, which mentioned a reduction in the intubation rate in helium-treated patients. Finally, there are a number of physiological studies in the context of COLD-COPD patients demonstrating a beneficial effect, mainly by a reduction in the resistive inspiratory work of breathing but also by a reduction in hyperinflation. Reduction of hypercapnia was mainly observed in spontaneously breathing and noninvasively ventilated helium-treated patients but not in intubated patients during controlled ventilation, suggesting that the decrease in PaCO2 was mainly in relation to a diminution in CO2 production, related to the diminution in work of breathing and not an improved alveolar ventilation. Moreover, there is little evidence that helium-oxygen could improve parameters of heterogeneity in such patients. Two RCTs were unable to demonstrate a reduction in the intubation rate in such setting, but they were likely underpowered. An adequately powered international multicentric study is ongoing and will help to determinate the exact place of the helium-oxygen mixture in the future. The place of the mixture during the weaning period will deserve further evaluation.
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PMID:Helium in the adult critical care setting. 2190 68

The noble gas helium has many applications owing to its distinct physical and chemical characteristics, namely: its low density, low solubility, and high thermal conductivity. Chiefly, the abundance of studies in medicine relating to helium are concentrated in its possibility of being used as an adjunct therapy in a number of respiratory ailments such as asthma exacerbation, COPD, ARDS, croup, and bronchiolitis. Helium gas, once believed to be biologically inert, has been recently shown to be beneficial in protecting the myocardium from ischemia by various mechanisms. Though neuroprotection of brain tissue has been documented, the mechanism by which it does so has yet to be made clear. Surgeons are exploring using helium instead of carbon dioxide to insufflate the abdomen of patients undergoing laparoscopic abdominal procedures due to its superiority in preventing respiratory acidosis in patients with comorbid conditions that cause carbon dioxide retention. Newly discovered applications in Pulmonary MRI radiology and imaging of organs in very fine detail using Helium Ion Microscopy has opened exciting new possibilities for the use of helium gas in technologically advanced fields of medicine.
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PMID:The role of helium gas in medicine. 2391 29