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1.
Association between exogenous atrial natriuretic peptide (ANP) and hemodynamic changes was ascertained in 3 dogs with overt congestive heart failure (CHF(+)) and 3 dogs without congestive heart failure (CHF(-)) caused by experimental mitral regurgitation (MR). The hemodynamic measurements were recorded in all dogs during and after 1 hr infusion of ANP at the rate of 0.1 (low dose), 0.5 (medium dose) and 1.0 (high dose) microg/kg/min, respectively. Heart rate, mean arterial pressure, pulmonary capillary wedge pressure (PCWP) and systemic vascular resistance decreased significantly during and after ANP infusion even with low dose in the CHF(+). Stroke volume, stroke volume index and cardiac output in the CHF(+) during and after ANP infusion showed an increasing trend as compared with the CHF(-). Double product, an indicator of myocardial oxygen consumption, significantly decreased during and after ANP administration at all doses in the CHF(+). These findings indicate that even at low dose, exogenous ANP improves cardiac performance and reduces myocardial oxygen consumption in the CHF(+), and suggest that ANP has beneficial effects in the treatment of dogs with overt congestive heart failure resulting from MR.  相似文献   

2.
OBJECTIVE: To quantify and compare intracellular magnesium concentrations (Mgi) in clinically normal dogs (control dogs) and dogs that have gastric dilatation-volvulus (GDV dogs) and to determine whether there is a difference in Mgi and serum magnesium concentrations (Mgs) between GDV dogs with and without cardiac arrhythmias. ANIMALS: 41 control dogs and 21 GDV dogs. PROCEDURE: Rectus abdominis muscle specimens were obtained from control and GDV dogs for determination of Mgi. Blood samples were obtained from GDV dogs for determination of Mgs, and dogs were monitored for 48 hours for cardiac arrhythmias. Muscle specimens were frozen at -40 C, oven dried at 95 C, and digested with concentrated nitric acid. Multielemental analyses were performed by simultaneous/sequential inductively coupled plasma-atomic emission spectroscopy with fixed-cross flow nebulization. The Mg, was standardized to sulfur content to correct for the amount of fat and fascia in the muscle specimen. Mean (+/- SEM) values were recorded in parts per million (ppm). Results-There were no significant differences in Mgi between control (627 +/- 11.1 ppm) and GDV (597 +/- 20.5 ppm) dogs, in Mgi between GDV dogs with (590 +/- 34 ppm) and without (584 +/- 29 ppm) cardiac arrhythmias, and in Mgs between GDV dogs with (1.77 +/- 0.26 ppm) and without (1.51 +/- 0.09 ppm) cardiac arrhythmias. There was no correlation between Mgs and Mgi (R2 = 0.0001). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that Mg depletion is not pathophysiologically important in dogs with GDV and does not play a role in the cardiac arrhythmias detected in these patients.  相似文献   

3.
OBJECTIVE: To evaluate the effects of a hemoglobin-based oxygen carrier (HBOC-301) on left ventricular preload, afterload, contractility, and ventriculo-arterial coupling in anesthetized dogs. STUDY DESIGN: A prospective experimental study. ANIMALS: Seven adult male dogs weighing 2.3 to 2.7 kg. METHODS: The study was performed on intact, closed-chest, chloralose-anesthetized dogs. Heart rate, left ventricular end-systolic and end-diastolic volume and pressure, cardiac output, stroke volume, blood resistivity, mean arterial pressure (MAP), dP/dtmax, end-systolic elastance (Ees), systemic vascular resistance (SVR), effective arterial elastance (Ea), left ventricular-arterial coupling (Ees/Ea), and myocardial oxygen consumption (MVO2) were determined during a 90-minute infusion of 30 mL/kg (20 mL/kg/h) of HBOC-301 and for 90 minutes thereafter. RESULTS: The administration of HBOC-301 significantly decreased packed cell volume, blood resistivity, heart rate, cardiac output, and dP/dtmax and significantly increased left ventricular end-diastolic and end-systolic pressure, MAP, and SVR. The Ea, Ees, Ees/Ea and MVO2 did not change. CONCLUSIONS: HBOC-301 produced insignificant changes in load independent indexes of cardiac performance (Ees, E, Ees/Ea) in anesthetized dogs. The collective directional changes in these variables, however, in conjunction with significant increases in SVR were most likely responsible for a decrease in cardiac output. Increases in SVR and the volume load (30 mL/kg) contributed to increases in left ventricular end-diastolic pressure. CLINICAL RELEVANCE: HBOC-301 infusion should be monitored and administered cautiously to dogs with poor ventricular function.  相似文献   

4.
Gastric dilatation-volvulus (GDV) was created experimentally and maintained for 90 minutes in 16 anesthetized, mixed-breed dogs. After the GDV was corrected, normal saline solution (0.044 mL/kg intravenously [IV]) was administered to eight dogs (controls), and flunixin meglumine (2.2 mg/kg IV) was administered to eight dogs. Microspheres labeled with radioactive cobalt, scandium, tin, or niobium were injected intravenously at baseline (before GDV) and minutes 90, 100, and 270, respectively, to determine tissue blood flows. Plasma endotoxin and prostacyclin were measured at the same intervals. Electrocardiogram, mean arterial pressure, portal pressure, and cardiac output were recorded continuously. Dogs were euthanatized at minute 270 and necropsied. There was no significant difference between treatment groups for any measured variable at any time. Endotoxin levels increased significantly during GDV. Prostacyclin levels were lower in dogs treated with flunixin meglumine than in controls at minutes 210 and 270. Histopathologic findings were similar for all dogs and consistent with those associated with endotoxemia. Flunixin meglumine treatment did not alter cardiac indices or tissue blood flows significantly. However, elevation of prostacyclin was inhibited by flunixin meglumine, which suggested that continued effects of endotoxic damage might be attenuated or inhibited.  相似文献   

5.
The gastric distention-volvulus (GDV) syndrome occurs commonly in large-breed dogs and may prove fatal in 15-68% of cases. Approximately 43% of cases with gastric distention (GD) or volvulus develop cardiac arrhythmias that can contribute to mortality. Most of these arrhythmias are ventricular in origin and ventricular fibrillation (VF) may be the cause of death. This study used an iatrogenic model of acute GD to investigate the prevalence of ventricular arrhythmias during acute GD and its recovery, if programmed electrical stimulation (PES) may uncover tendency to VF, if the Q-T interval corrected for heart rate (Q-Tc) of the electrocardiogram (ECG) predicts tendency to VF, and if hemodynamic changes predate VF. Eleven beagles, anesthetized with morphine and alpha-chloralose, and instrumented so that vascular pressures, cardiac output, and PES could be recorded, were used. Five were unperturbed, whereas acute GD to a pressure of 30 mm Hg for 1.5 hours was produced in 6 others. The results were as follows. No dogs with GD developed spontaneously occurring arrhythmias. VF was produced in no dogs by conventional PES, but occurred in all dogs (P < .05) with GD and none of the controls, using accelerated ventricular pacing. The Q-Tc interval of the ECG prolonged minimally in dogs with GD, and shortened (P < .05) in controls. Some hemodynamic changes did predate VF. In conclusion, dogs with acute GD have a tendency for VF, which may be uncovered by accelerated PES. The mechanism for the vulnerability to arrhythmia with GD is unknown.  相似文献   

6.
Objective: To determine changes in hemodynamic and cardiac energetic parameters in dogs after induction of portal hypertension and gastric ischemia. These blood flow alterations are similar to changes seen in splanchnic blood flow in dogs with gastric dilatation volvulus syndrome (GDV). Design: Original experimental study. Setting: Veterinary teaching hospital. Animals: Seven purpose‐bred, intact male dogs. Interventions: Standard midline laparotomy and median sternotomy were performed under general anesthesia. Dogs were instrumented to obtain arterial blood pressure, aortic flow, cardiac chamber pressures, central venous pressure, portal flow, and portal pressure. Colored microsphere technology was used for the determination of myocardial blood flow. Measurements and samples were obtained at baseline, following induction of portal hypertension, and after induction of portal hypertension and gastric ischemia. Measurements and main results: Left ventricular myocardial blood flow was increased from 81.8±20.1 mL/100 g/min at baseline to 127.7±57.2 mL/100 g/min (P=0.02) after induction of portal hypertension and gastric ischemia. Myocardial oxygen consumption increased from 142.2±27.4 J/min/100 g at baseline to 219.1±33.4 J/min/100 g (P=0.003) after induction of portal hypertension and gastric ischemia, but cardiac external work remained unchanged (13.67±6.2 to 13.27±9.6 J/min; P=0.78; power=0.79). Cardiac efficiency decreased from 11.6±6.1% at baseline to 7.6±5.1% (P=0.017) after induction of portal hypertension and gastric ischemia. Conclusions: Transfer of energy within the myocardium was less efficient after induction of portal hypertension and ischemia of the stomach wall. On the basis of these results, alterations in cardiac function associated with GDV may result from deterioration of cardiac efficiency.  相似文献   

7.
OBJECTIVE: To measure cardiopulmonary variables, including cardiac index, in dogs with naturally acquired gastric dilatation-volvulus (GDV). DESIGN: Prospective clinical study. ANIMALS: 6 dogs with GDV. PROCEDURE: In addition to typical medical and surgical management of GDV, the dorsal metatarsal and pulmonary arteries and right atrium of the dogs were catheterized to obtain cardiopulmonary measurements before and during anesthesia and surgery. RESULTS: All dogs underwent gastropexy but none required gastrectomy. Mean cardiac index and mean arterial blood pressure for this small population of dogs with GDV were not significantly different from those reported for clinically normal awake or anesthetized dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs with naturally acquired GDV without gastric necrosis may not have the classic characteristics, including decreased cardiac index and hypotension, of hypovolemic circulatory shock.  相似文献   

8.
OBJECTIVE: To evaluate the cardiovascular effects of norepinephrine (NE) and dobutamine (DB) in isoflurane-anesthetized foals. STUDY DESIGN: Prospective laboratory study. METHODS: Norepinephrine (0.05, 0.10, 0.20, and 0.40 microg kg(-1) minute(-1)) and dobutamine (2.5, 5.0, and 10 microg kg(-1) minute(-1)) were alternately administered to seven healthy, 1- to 2-week-old isoflurane-anesthetized foals. Arterial and pulmonary arterial blood pressure, right atrial pressure, pulmonary artery occlusion pressure, heart rate, body temperature, cardiac output, arterial and mixed venous blood pH, partial pressure of carbon dioxide, partial pressure of oxygen [arterial partial pressure of oxygen (PaO(2)) and mixed venous partial pressure of oxygen (PvO(2))], and packed cell volume were measured. Standard base excess, bicarbonate concentration, systemic and pulmonary vascular resistance, cardiac index (CI), stroke volume, left and right stroke work indices, oxygen delivery (DO(2)), consumption, and extraction were calculated. Results Norepinephrine infusion resulted in significant increases in arterial and pulmonary arterial pressure, systemic and pulmonary vascular resistance indices, and PaO(2); heart rate was decreased. Dobutamine infusion resulted in significant increases in heart rate, stroke volume index, CI, and arterial and pulmonary arterial blood pressure. Systemic and pulmonary vascular resistance indices were decreased while the ventricular stroke work indices increased. The PaO(2) decreased while DO(2) and oxygen consumption increased. Oxygen extraction decreased and PvO(2) increased. CONCLUSIONS AND CLINICAL RELEVANCE: Norepinephrine primarily augments arterial blood pressure while decreasing CI. Dobutamine primarily augments CI with only modest increases in arterial blood pressure. Both NE and DB could be useful in the hemodynamic management of anesthetized foals.  相似文献   

9.
Blood was withdrawn from 15 dogs over the course of about 1 hour until the mean arterial blood pressure was reduced to 60 mm Hg. Small aliquots of additional blood were withdrawn in order to maintain the mean arterial blood pressure near 60 mm Hg for an additional hour. Oxymorphone (0.4 mg/kg) was then administered intravenously to ten dogs, and all measurements were repeated in 5, 15, 30, and 60 minutes. Five dogs served as controls.
Heart rate, tidal volume, arterial oxygen, oxygen extraction, and pH significantly decreased after oxymorphone administration, while systemic and pulmonary arterial blood pressures, systemic vascular resistance (transiently), breathing rate, minute ventilation, physiologic dead space, venous admixture, venous oxygen, arterial and venous carbon dioxide, and bicarbonate concentration increased significantly. Cardiac output was also increased, but the change was not statistically significant. Oxymorphone was associated with significantly lower heart rate, tidal volume, arterial oxygen, and pH, and higher systemic and pulmonary arterial pressure, cardiac output, venous oxygen, and arterial and venous carbon dioxide, compared to the control group, which did not receive oxymorphone.
Oxymorphone significantly improved cardiovascular performance and tissue perfusion in these hypovolemic dogs. Oxymorphone did cause a significant increase in arterial carbon dioxide and a decrease in arterial oxygenation. Oxymorphone is an opioid agonist that may represent a reasonable alternative for the induction of anesthesia in patients who are candidates for induction hypotension.  相似文献   

10.
Xylazine and xylazine-ketamine in dogs   总被引：3，自引：0，他引：3  
The cardiopulmonary consequences of IV administered xylazine (1.0 mg/kg) followed by ketamine (10 mg/kg) were evaluated in 12 dogs. Xylazine caused significant decreases in heart rate, cardiac output, left ventricular work, breathing rate, minute ventilation, physiologic dead space, oxygen transport, mixed venous partial pressure of oxygen, and oxygen concentration. It caused significant increases in systemic blood pressure, central venous pressure, systemic vascular resistance, tidal volume, and oxygen utilization ratio. The subsequent administration of ketamine was associated with significant increases in heart rate (transient increase), cardiac output, the alveolar-arterial PO2 gradient and venous admixture (transient increase), and arterial PCO2 (transient increase). It caused significant decreases in stroke volume (transient decrease), left ventricular stroke work (transient decrease), effective alveolar ventilation, arterial PO2 and oxygen content (transient decrease).  相似文献   

11.
The purpose of this study was to compare the cardiovascular effects of halothane when used alone at increasing doses (1.2, 1.45 and 1.7 minimum alveolar concentration, MAC) to those produced with equipotent doses of halothane after potentiation of the anesthetic effect with acepromazine (ACP) sedation (45% reduction of halothane MAC). Six healthy mature dogs were used on three occasions. The treatments were halothane and intramuscular (IM) saline (1.0 mL), halothane and ACP (0.04 mg/kg IM), or halothane and ACP (0.2 mg/kg IM). Anesthesia was induced and maintained with halothane in oxygen and the dogs were prepared for the collection of arterial and mixed venous blood and for the determination of heart rate, systolic, diastolic and mean arterial pressure, mean pulmonary arterial pressure (PAP), central venous pressure and cardiac output. Following animal preparation the saline or ACP was administered and positive pressure ventilation instituted. Twenty-five minutes later the dogs were exposed to the first of three anesthetic levels, with random assignment of the sequence of administration. At each anesthetic level, measurements were obtained at 20 and 35 min. Calculated values included cardiac index, stroke index, left ventricular work, systemic vascular resistance, arterial oxygen content, mixed venous oxygen content, oxygen delivery and oxygen consumption. Heart rate was significantly higher with halothane alone than with both halothane-ACP combinations and was significantly higher with high dose ACP compared to low dose ACP. Systolic and mean blood pressures were lowest with halothane alone and highest with 0.2 mg/kg ACP, the differences being significant for each treatment. Oxygen uptake and PAP were significantly lower in dogs treated with ACP. It was concluded that ACP does not potentiate the cardiovascular depression that accompanies halothane anesthesia when the resultant lower dose requirements of halothane are taken into consideration.  相似文献   

12.
Cardiac troponin I (cTnI) and T (cTnT) have a high sequence homology across phyla and are sensitive and specific markers of myocardial damage. The purpose of this study was to evaluate the Cardiac Reader, a human point-of-care system for the determination of cTnT and myoglobin, and the Abbott Axsym System for the determination of cTnI and creatine kinase isoenzyme MB (CK-MB) in healthy dogs and in dogs at risk for acute myocardial damage because of gastric dilatation-volvulus (GDV) and blunt chest trauma (BCT). In healthy dogs (n = 56), cTnI was below detection limits (<0.1 microg/L) in 35 of 56 dogs (reference range 0-0.7 microg/L), and cTnT was not measurable (<0.05 ng/mL) in all but 1 dog. At presentation, cTnI, CK-MB, myoglobin, and lactic acid were all significantly higher in dogs with GDV (n = 28) and BCT (n = 8) than in control dogs (P < .001), but cTnT was significantly higher only in dogs with BCT (P = .033). Increased cTnI or cTnT values were found in 26 of 28 (highest values 1.1-369 microg/L) and 16 of 28 dogs (0.1-1.7 ng/mL) with GDV, and in 6 of 8 (2.3-82.4 microg/L) and 3 of 8 dogs (0.1-0.29 ng/mL) with BCT, respectively. In dogs suffering from GDV, cTnI and cTnT increased further within the first 48 hours (P < .001). Increased cardiac troponins suggestive of myocardial damage occurred in 93% of dogs with GDV and 75% with BCT. cTnI appeared more sensitive, but cTnT may be a negative prognostic indicator in GDV. Both systems tested seemed applicable for the measurement of canine cardiac troponins, with the Cardiac Reader particularly suitable for use in emergency settings.  相似文献   

13.
Objective: To collate canine cardiopulmonary measurements from previously published and unpublished studies in instrumented, unsedated, normovolemic and moderately hypovolemic dogs. Design: Collation of data obtained from original investigations in our research laboratory. Setting: Research laboratory, School of Veterinary Medicine. Subjects: Sixty‐eight dogs. Interventions: Subjects were percutaneously instrumented with an arterial catheter and a thermodilution cardiac output catheter. A femoral artery catheter was percutaneously placed for blood removal. Measurements and main results: Body weight, arterial and mixed‐venous pH and blood gases, arterial, pulmonary arterial, pulmonary artery occlusion, and central venous blood pressure, cardiac output, and core body temperature were measured. Body surface area, bicarbonate concentration, standard base excess, cardiac index (CI), stroke volume, systemic and pulmonary vascular resistance, left and right ventricular work and stroke work indices, left and right rate‐pressure product, alveolar PO2, alveolar–arterial PO2 gradient, arterial and mixed‐venous and pulmonary capillary oxygen content, oxygen delivery, oxygen consumption, oxygen extraction, venous admixture, arterial and venous blood carbon dioxide content, arterial–venous carbon dioxide gradient, carbon dioxide production were calculated. In 68 dogs, hypovolemia sufficient to decrease mean arterial blood pressure (ABPm) to an average of 62 mmHg, was associated with the following changes: arterial partial pressure of carbon dioxide (PaCO2) decreased from 40.0 to 32.9 mmHg; arterial base deficit (BDa) increased from ?2.2 to ?6.3 mEq/L; lactate increased from 0.85 to 10.7 mm /L, and arterial pH (pHa) did not change. Arterial partial pressure of oxygen (PaO2) increased from 100.5 to 108.3 mmHg while mixed‐venous PO2 (PmvO2) decreased from 49.1 to 34.1 mmHg. Arterial and mixed‐venous oxygen content (CaO2 and CmvO2) decreased from 17.5 to 16.5 and 13.8 to 9.6 mL/dL, respectively. The alveolar–arterial PO2 gradient (A‐a PO2) increased from 5.5 to 8.9 mmHg while venous admixture decreased from 2.9% to 1.4%. The ABPm decreased from 100 to 62 mmHg; pulmonary arterial pressure (PAPm) decreased from 13.6 to 6.4 mmHg; and pulmonary arterial occlusion pressure (PAOP) decreased from 4.9 to 0.1 mmHg. CI decreased from 4.31 to 2.02 L/min/m2. Systemic and pulmonary vascular resistance (SVRI and PVRI) increased from 1962 to 2753 and 189 to 269 dyn s/cm5, respectively. Oxygen delivery (DO2) decreased from 787 to 340 mL/min/m2 while oxygen consumption (VO2) decreased from 172 to 141 mL/min/m2. Oxygen extraction increased from 20.9% to 42.3%. Conclusions: Moderate hypovolemia caused CI and oxygen delivery to decrease to 47% and 42% of baseline. Oxygen extraction, however, doubled and, therefore, oxygen consumption decreased only to 82% of baseline.  相似文献   

14.
This study demonstrated new approaches which enabled evaluating the work performance in both ventricles of an isolated guinea pig heart. By changing the right atrial filling pressure (RAFP, preload) from 6 to 20 mm of Hg at a constant aortic pressure (Pa, 20 mm of Hg), cardiac output, stroke volume, aortic flow, coronary flow, cardiac work, O2 consumption, CO2 output, as well as end-diastolic ventricular, and pulmonary arterial pressures increased. Cardiac contractility and both ventricular systolic pressures reached peak values between 12 and 14 mm of Hg of RAFP and then gradually decreased. With graded increases of Pa (afterload) from 10 to 45 mm of Hg at a fixed RAFP (8 mm of Hg), coronary flow, cardiac contractility, cardiac work, cardiac O2 consumption, glucose utilization rate, and pulmonary arterial and both ventricular systolic pressures increased. Although aortic flow decreased with an increase in Pa, cardiac output, stroke volume, and coronary resistance did not show significant changes. Furthermore, cardiac mechanical efficiency decreased with an increase of pre- or afterload of the perfused isolated heart. These findings indicate that the total working heart model is suitable for studying cardiac functions.  相似文献   

15.
We investigated small-volume (5 ml/kg) 7% NaCl in 6% dextran 70 (HS/D70) as an alternative to large-volume (60 ml/kg) 0.9% NaCl for treatment of experimentally induced canine gastric dilatation-volvulus (GDV) shock. The stomach was surgically displaced and then distended with an intragastric balloon in 11 dogs anesthetized with pentobarbital. All dogs were subjected to GDV for 180 minutes before partial decompression and resuscitation. Hemodynamic values, blood gas values, and plasma volume were measured during control, shock, and resuscitation periods. Resuscitation started with 1 group (n = 6) receiving 5 ml of HS/D70/kg, iv, over 5 minutes, and the other group (n = 5) receiving 60 ml of 0.9% NaCl/kg, IV, over 60 minutes. Both groups received a surgical maintenance dosage (20 ml/kg/h) of 0.9% NaCl after initial resuscitation. Resuscitative effects of small-volume HS/D70 were similar to large-volume 0.9% NaCl during the first hour of treatment; however, cardiac output was significantly higher in the HS/D70 group for the last 2 hours of resuscitation. Changes in heart rate, left ventricular pressure change, and systemic vascular resistance appeared to be responsible for improved perfusion. Mixed venous oxygen partial pressure data supported improved perfusion in the HS/D70 group. Packed cell volume remained higher in the HS/D70 group, indicating less hemodilution and improved oxygen delivery. Resuscitation of this GDV-induced shock model was better sustained with small-volume HS/D70, compared with conventional large-volume 0.9% NaCl.  相似文献   

16.
The load-reducing effect of nitroglycerin (NTG), a vasodilator, was studied in dogs with heart failure. The chordae tendineae of the mitral valve were transected to induce acute mitral regurgitation (MR) for hemodynamic evaluation. By such surgical treatment, preload indices such as left ventricular end-diastolic pressure (LVEDP) and left atrial pressure (LAP) increased significantly, and subsequent cardiac dysfunction and heart failure were indicated by another decrease in stroke volume, myocardial contractility, forward flow, and myocardial oxygen consumption. To dogs with artificially established acute MR, 3 micrograms/kg/min of NTG was administered intra-arterially by means of a continuous infusion, that resulted in decrease of LVEDP, LAP and central venous pressure (CVP). Thus, a reduction of preload was determined. Simultaneously, afterload indices such as aortic systolic pressure (Aos), aortic mean pressure (Aom) and total peripheral resistance (TPR) decreased remarkably. Afterload reduction depended on the amount of venous return; therefore, an extra-corporeal circulation system was applied in order to supply a constant venous return before NTG administration. This caused a significant decrease in aortic diastolic pressure (Aod), Aos, Aom, left ventricular systolic pressure (LVSP) and TPR, and an increase in myocardial contractility and cardiac output. This suggested that afterload reduction might be realized by the vasodilatory effect of NTG on the resistance vessels.  相似文献   

17.
Using adult mongrel dogs, experiments were performed to elucidate the relationship between the changes in the myocardial oxygen tension (PmO2) in anoxia and disturbances of cardiac function. Dogs, forced to inspire 100% N2, suffered from a respiratory arrest after 5 min, and developed acute anoxia. However, by 100% O2 inhalation 2 min after the onset of the respiratory arrest, the anoxia rapidly resolved. The arterial oxygen tension (PaO2), left intra ventricular oxygen tension (PLVO2) and PmO2 showed the most pronounced fall 2 min after the respiratory arrest induced by N2 inhalation. The arterial carbon deoxide tension (PaCO2) decreased until the respiratory arrest, after which it started to rise. When inhalation of 100% O2 was initiated at the anoxia, the PaO2, PLVO2 and PmO2 recovered within 1 min followed by a rise beyond the baseline value. Left ventricular end-diastolic pressure (LVEDP), left atrial mean pressure (LAm), left ventricular systolic pressure (LVSP), aortic mean pressure (Aom), maximum rate of force development by left ventricle (LVmax.dp/dt), total peripheral resistance (TPR), cardiac output (CO) and heart rate (HR) were measured. At the onset of anoxia, these parameters decreased sharply. When inhalation of 100% O2 was initiated within 2 min of the respiratory arrest, these disturbances of cardiac function recovered rapidly. The fall of PmO2 plays an important role in the impairment of cardiac function.  相似文献   

18.
Cardiopulmonary effects of laparoscopic surgery were investigated in five crossbred dogs (21 ± 1.9 kg). Premedicated dogs were anesthetized with thiopental and maintained with halothane at 1.5 times minimum alveolar concentration in oxygen. Controlled ventilation maintained partial pressure of end-tidal co2 at 40 ± 2 mm Hg. Vecuronium was used for skeletal muscle relaxation. After instrumentation and stabilization, baseline measurements were made of cardiac output (thermodilution technique), mean systemic, mean pulmonary arterial and pulmonary wedge pressures, heart rate, saphenous vein and central venous pressures, and minute ventilation. Baseline arterial and mixed venous blood samples were drawn for analysis of pH, Pao2, Paco2, Pvo2, Pvco2, and bicarbonate concentrations. Systemic and pulmonary vascular resistances, oxygen delivery and consumption, shunt fraction, and dead space ventilation were calculated using standard formulas. Abdominal insufflation using co2 to a pressure of 15 mm Hg for 180 minutes resulted in significant ( P <.05) increases in heart rate (15 to 180 minutes), minute ventilation (75 to 135 minutes), and saphenous vein pressure (15 to 180 minutes), and decreases in pH (60 to 180 minutes) and Pao2 (60 to 180 minutes). For 30 minutes after desufflation, there was a significant decrease in Pao2, and increases in cardiac output, o2 delivery, and heart rate, compared with baseline. There was a significant increase in shunt fraction and decrease in pH at 15 minutes after desufflation only. The changes were within physiologically acceptable limits in these healthy, ventilated dogs.  相似文献   

19.
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20.
In veterinary medicine, dopamine is currently being administered clinically by infusion for treatment of kidney disorders at low doses (< or = 3 microg/kg/min) and for assessment of hemodynamics at high doses (> or = 5 microg/kg/min). However, since high doses of dopamine cause peripheral vasoconstriction due to its effect on alpha adrenoceptors, high doses have no longer been recommended. The present study was conducted to explore possible regimens for the use of dopamine infusion in dogs. The regional (renal and cardiac) blood flow for 60 min was measured by using colored microspheres at three doses (3, 10 and 20 microg/kg/min) of dopamine infusion in healthy anesthetized mongrel dogs. The effects on kidney and peripheral hemodynamics at each dose and the resultant cardiac output, mean arterial blood pressure and total peripheral resistance were determined. Renal blood flow increased markedly at 3 microg/kg/min dopamine. Improvement in hemodynamics indicated by marked increase in cardiac blood flow, cardiac output and mean arterial blood pressure and decreased total peripheral resistance was observed at higher doses (10 and 20 microg/kg/min). At 10 microg/kg/min, in addition to the satisfactory increase in cardiac blood flow, there was also a stable satisfactory increase in renal blood flow. However, at 20 microg/kg/min, increased myocardial oxygen consumption (manifested by marked increased in cardiac output), arrythmia and irregular increase in renal blood flow were detected. This study suggests that the clinical use of dopamine infusion in dogs could be safely expanded to moderately higher doses.  相似文献   

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