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

Symptomatic carotid atherosclerotic disease occurring as a result of cervical irradiation often requires surgical intervention. Airway obstruction is an uncommon problem after most carotid surgery and has not been described for patients with cervical irradiation. Airway obstruction developed after two of five carotid endarterectomy procedures in previously irradiated necks requiring emergency tracheostomy or reintubation. Mechanisms of obstruction included endotracheal tube trauma to the fixed irradiated vocal cords and laryngeal edema caused by surgical dissection in an irradiated field. In addition, one patient in our series demonstrated hypercarbia as a result of bilateral carotid body ablation, a process known to impair the ventilatory response to hypoxia. An increased risk of airway obstruction after carotid surgery exists in patients with prior cervical irradiation. Preventive methods include the use of perioperative steroids and either carotid surgery with local anesthesia or bronchoscopic vocal cord visualization and intubation.
J Cardiovasc Surg (Torino)
PMID:Airway compromise after carotid surgery in patients with cervical irradiation. 260 Jan 15

The effect of autotransplantation of the left lung on respiratory regulation was studied in four dogs in pentobarbital anaesthesia. In each dog the electrical and mechanical activity of the inspiratory muscles was studied before and 4-6 weeks, 3, 6 and 12 months after the transplantation. No or very little change was found in comparisons of spontaneous respiration or response to inhalation of carbon dioxide, hypoxia or combined hypercapnia and hypoxia. When the airways were closed after inflation with varying volumes of air, the increase in number and frequency of the electromyographic impulses in the intercostal muscles and the diaphragm (compared with the preceding unobstructed breaths) was greater before than after the lung autotransplantation. The duration of the first respiratory cycle after airway closure increased progressively with the volume of inflation in intact dogs and in dogs with autotransplanted left lung, though the increase was approximately halved following autotransplantation.
Scand J Thorac Cardiovasc Surg 1987
PMID:Effect of lung autotransplantation on breathing regulation. Studies in dogs. 312 3

High-frequency jet ventilation (HFJV) via a catheter with internal diameter 2.4 mm was employed in 21 patients to facilitate airway reconstructive surgery. Tracheal reconstruction was performed in six cases, sleeve lobectomy in six and sleeve pneumonectomy in nine. An HFO-Jet-Ventilator was used at individually selected settings of 0.5-2.4 kg/cm2 for driving gas pressure and 4-10 Hz frequency. Intermittent positive pressure ventilation (IPPV) was used initially, with switch to HFJV at the time of tracheobronchial reconstruction. The time during which HFJV was employed ranged from 25 to 65 min. Except for transient hypoxia or hypercapnia in a few patients, the results of blood gas analyses during HFJV were satisfactory. The most appropriate HFJV settings for each surgical procedure and the advantages of HFJV over IPPV are discussed.
Scand J Thorac Cardiovasc Surg 1988
PMID:The clinical value of high-frequency jet ventilation in major airway reconstructive surgery. 322 25

Papillary muscle preparations from rats with normal arterial oxygen and carbon dioxide tensions and from rats which had been maintained with normal oxygen tension but with hypercapnia for 28 days (FICO2 = 5%) were subjected to acute hypercapnia with or without amiloride, a competitive inhibitor of the Na+/H+ pump. Acclimatisation to hypercapnia reduced the slope of the line relating log tension against the extracellular pH from 0.96(SEM0.06) to 0.71(0.07) (p less than 0.02). Amiloride increased the slope in unacclimatised muscle to 1.39(0.09), p less than 0.001 and in muscles acclimatised to hypercapnia to 1.03(0.13), p less than 0.05. The slope in acclimatised muscles was significantly less steep than in unacclimatised muscle (p less than 0.05). The sarcolemmal Na+H+ exchanger is important in the protection of rat cardiac muscle against acute respiratory acidosis.
Cardiovasc Res 1988 Nov
PMID:Effect of amiloride on contractility of rat cardiac muscle exposed to chronic hypercapnia and acute acidosis. 325 18

In combined heart-lung transplantation the afferent nerve pathways inevitably are transsected. In previous studies with en bloc heart-lung transplantation in dogs, we found altered regulation of breathing-abolition of Hering-Breuer reflex and response to hypercapnia inhalation stimulus consisting of augmented tidal volume with no change in respiratory rate-shortly after the operation. The long-term effects of pulmonary denervation on breathing regulation were now studied in dogs after staged bilateral pulmonary autotransplantation. Mechanical and electrical activities of the respiratory muscles were recorded during spontaneous breathing and after deflation and inflation with varying volumes of air. Five months postoperatively the duration of the respiratory cycle increased 2.5 times on inflation with 600 ml of air and occlusion of the airways, compared with tenfold prolongation in intact control dogs, indicating a partial return of the Hering-Breuer reflex after the autotransplantation. The duration of the EMG bursts in respiratory muscles increased in intact dogs and in those with bilateral lung autotransplants. In impulse frequency the response to stretching was less evident after autotransplantation. The mechanism mediating reappearance of Hering-Breuer reflex warrants further study.
Scand J Thorac Cardiovasc Surg 1987
PMID:Reappearance of Hering-Breuer reflex after bilateral autotransplantation of the lungs. 329 61

Fifty-six patients undergoing open-heart surgery were monitored for red cell trauma during cardiopulmonary bypass (CPB), using a standard red cell microfiltration method. The average red cell deformability was reduced by 38%. Respirator time was shorter in the patients with lesser degrees of red cell trauma, and vice versa. After extubation, the tendency to hypercapnia was greatest in the patients with most red cell trauma during CPB. Hypoxic tendencies in the first 24 postextubation hours were comparably distributed among all levels of red cell trauma.
Scand J Thorac Cardiovasc Surg 1988
PMID:Association between pulmonary dysfunction and reduced red cell deformability following cardiopulmonary bypass. 340 93

The relative importance of hypercapnia in the control of coronary circulation was examined in 42 anaesthetised open chest rabbits. Coronary blood flow was determined with 15 micron radioactive microspheres. When mean (SD) Paco2 was increased from 38(10) to 76(16) mm Hg in six rabbits, the hypercapnia caused a 62% increase in coronary blood flow. When a similar degree of metabolic acidosis was induced in 12 rabbits for either 15 or 60 min, no changes in coronary blood flow occurred. No increases in coronary blood flow occurred during hypercapnia with propranolol, 2 mg/kg (n = 12), with or without atrial pacing to maintain heart rate. Similarly, carotid denervation prevented the carbon dioxide induced increase in coronary blood flow in six rabbits. Haemodiluted rabbits (n = 6) with a 40% replacement of blood showed no changes in coronary blood flow with hypercapnia. This was due to the 22% decrease in systolic pressure-time index, despite their intact sympathetic nervous system and reduced Bohr shift. Therefore, although carbon dioxide is a coronary vasodilator, both direct vasodilatation and sympathetic adrenergic activation must be intact in order for coronary blood flow to be increased.
Cardiovasc Res 1986 Feb
PMID:Effect of hypercapnia on coronary circulation. 370 47

The aim of the present study was to determine whether the diversion of blood flow away from a collapsed pulmonary lobe is due to hypoxic pulmonary vasoconstriction alone, or whether hypercapnia and mechanical factors also contribute. Hypoxic pulmonary vasoconstriction was tested in a canine pulmonary left lower lobe. Alveolar hypoxia was produced by absorption collapse or by ventilation with 7% oxygen, which has previously been shown to produce an end-pulmonary capillary pO2 similar to mixed venous pO2. The proportion of the cardiac output flowing to the lobe was reduced in both hypoxic states but was significantly lower during collapse than during ventilation hypoxia. The beta 1-adrenergic agonist dobutamine hydrochloride (30 micrograms X kg-1 X min-1 iv) produced a significant increase in the proportion of the cardiac output flowing to the lobe during collapse but no significant change during ventilation hypoxia. It is concluded that changes in local pCO2 during collapse may account for the greater diversion of blood flow from the lobe when compared with ventilation hypoxia.
Cardiovasc Res 1985 May
PMID:Pulmonary lobe blood flow during ventilation hypoxia and lobar collapse in the dog. 399 22

Patients with pulmonary dysfunction and CO2 retention have renal hemodynamic abnormalities accompanied by increased plasma renin activity. To determine if hypercapnia impairs renal function, particularly through the renin-angiotensin system, the effects of acute hypercapnic acidosis (HC), using 8.5% CO2, were measured in five unanesthetized dogs during (a) the intact state; (b) renin-angiotensin antagonism using either 1-sarcosine, 8-glycine angiotensin II ( [Sar1, Gly8] AII) or SQ 14,225; and (c) exogenous angiotensin II infusion. As partial arterial carbon dioxide pressure (PaCO2) increased (p less than 0.05) from control (C) of 35 +/- 1 (SEM) to 48 +/- 1 mm Hg during HC, arterial pH fell (p less than 0.05) from 7.36 +/- 0.01 to 7.24 +/- 0.005. Renal function was uncompromised with HC, and glomerular filtration rate (GFR) and urinary sodium excretion increased (p less than 0.05) despite a fourfold rise in plasma renin activity from C of 0.6 +/- 0.3 to 2.2 +/- 0.8 ng AI ml-1 h-1 during HC. Administration of [Sar1, Gly8] AII during HC did not consistently alter systemic or renal hemodynamic responses, and effects of SQ 14,225 during HC were also observed during normocapnia. Although systemic vascular responses to exogenous AII infusion were similar, the renal vasoconstrictor response was antagonized during HC with unchanged GFR and renal blood flow. These findings indicate that despite activation of the renin-angiotensin system, acute hypercapnic acidosis is unassociated with impairment of renal function in unanesthetized dogs. This may be related to diminished renal vascular AII responsiveness during hypercapnia.
J Cardiovasc Pharmacol
PMID:Renal and cardiovascular responses to acute hypercapnic acidosis in conscious dogs: role of renin--angiotensin. 618 44

A new method for measuring blood flow in the colon using a 133Xenon clearance technique has been developed in the greyhound. Values for 133Xe tissue blood partition coefficient for colon have been established. The mean basal colon blood flow in 35 animals was 39.8 cm3.min-1.100g-1 with a coefficient of variation for repeat measurements of 8.7%. Hypercapnia produced a significant rise in colon blood flow to a mean maximum level of 62.2 cm3.min-1.100g-1 and hypocapnia a significant fall to a mean level of 27.9 cm3.min-1.100g-1. For arterial carbon dioxide tension (PCO2) values between 2 and 12 kPa (15 and 90 mmHg) there was a straight line relationship between colon blood flow and arterial PCO2. When hypercapnia was prolonged for 75 min, the initial rise in colon blood flow was only partially sustained, while prolonged hypocapnia for a similar period resulted in sustained reduction in flow. Mean resting colon oxygen consumption in 35 animals was 1.17 cm3.min-1.100g-1 and this was not significantly affected by hypocapnia. Hypercapnia to arterial PCO2 levels between 8 and 14 kPa (60 and 105 mmHg), however, produced a significant rise in colon oxygen consumption. Since changes in colon blood flow during and after surgery may affect healing of colonic anastomoses, these results may be relevant when considering anaesthetic techniques for patients undergoing colon resection.
Cardiovasc Res 1980 Jan
PMID:Colon blood flow in the dog: effects of changes in arterial carbon dioxide tension. 676 45


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