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1.
The pulmonary health of 66 horses was assessed by a clinical examination and simple supplementary diagnostic methods. Single breath diagrams for CO(2) (SBD-CO(2)) and derived lung function indices were used to determine pulmonary function. The clinical signs in different groups were related to the results of the lung function indices derived from the SBD-CO(2). In horses with moderate to severe chronic obstructive pulmonary disease (COPD), a significant relationship was found between the respiratory frequency and the ratio of Bohr's dead space to the tidal volume (VD(Bohr)/VT), and between the physiological dead space/tidal volume ratio (VD(phys)/VT) and the ratio of the alveolar dead space to the alveolar tidal volume (VD(alv)/VT(alv)), but no significant associations were found between the arterial oxygen tension (P(a)O(2)) and lung function indices derived from the SBD-CO(2). The occurrence of cough, the viscosity of tracheobronchial mucus and the amount of polynuclear neutrophils in tracheobronchial aspirates were significantly related to the expiratory tidal volume (VT), the total expired volume of CO(2) (VCO(2)), VD(Bohr)/VT, VD(phys)/VT and VD(alv)/VT(alv).We conclude that abnormal findings in these clinical parameters indicate a measurable ventilation and perfusion (V(A)/Q) mismatch which is reflected by increases in dead space, VD(Bohr)/VT and VD(phys)/VT as well as VD(alv)/VT(alv).  相似文献   

2.
The influence of pharmacologic enhancement of cardiac output on the alveolar-to-arterial oxygen tension (difference (P[A-a]O2), physiologic right-to-left shunt fraction (Qs/Qt), and physiologic dead space-to-tidal volume ratio (VD/VT) ws studied in halothane-anesthetized horses in left lateral, right lateral, and dorsal recumbencies. Adult horses were anesthetized, using xylazine (2.2 mg/kg, IM), guaifenesin (50 mg/kg, IV), thiamylal (4.4 mg/kg, IV), and halothane (1.5% to 2% inspired) in 100% O2. Mechanical ventilation was controlled to maintain arterial eucapnia (PaCO2) 35 to 45 mm of Hg) for a period lasting at least 1 hour. Dobutamine was administered at dosages of 1, 3, and 5 micrograms/kg/min, IV, on a randomized basis. The P(A-a)O2, Qs/Qt, and VD/VT were calculated during equilibration and after each dobutamine infusion was given. The P(A-a)O2 and Qs/Qt were significantly (P less than 0.05) greater and VD/VT tended to be greater in horses in dorsal recumbency, compared with those values in horses in left lateral or right lateral recumbency. Cardiac output was similar in all horses, regardless of body position (recumbency). The qualitative relationship between horses in the 3 recumbent positions were not altered by dobutamine. Cardiac output was significantly (P less than 0.05) increased by 3 or 5 micrograms of dobutamine/kg/min in all horses, whereas P(A-a)O2, Qs/Qt, and VD/VT were not significantly altered by dobutamine. The results of the present study failed to substantiate our clinical observations of decreased P(A-a)O2 and Qs/Qt in anesthetized compromised horses given dobutamine.  相似文献   

3.
OBJECTIVE: To investigate whether volumetric capnography indices could be used to differentiate between horses without recurrent airway obstruction (RAO) and horses with RAO that were in clinical remission or that had clinically apparent RAO. ANIMALS: 70 adult Swiss Warmblood horses (20 used for pleasure riding and 50 used for dressage or show jumping). PROCEDURE: Horses were allocated to 4 groups on the basis of history, clinical signs, results of endoscopy, and cytologic findings (group 1, 21 healthy horses; group 2, 22 horses with RAO that were in remission; group 3, 16 horses with mild RAO; group 4, 11 horses with exacerbated RAO). Expiratory volume and CO2 curves were recorded by use of a computerized ultrasonic spirometer. Volumetric capnograms were plotted, and derived indices were calculated. RESULTS: Dead-space volume (VD) was calculated by use of the Bohr equation (VD(Bohr)) and for physiologic VD (VD(phys)). Ratios for VD(Bohr) to expiratory tidal volume (VT) and VD(phys) to V(T) as well as an index of effective CO2 elimination were significantly different among groups of horses. Age and use of the horses also significantly affected volumetric capnography indices. CONCLUSIONS AND CLINICAL RELEVANCE: Ratios of VD(Bohr) to VT and VD(phys) to VT as well as an index of effective CO2 elimination were sufficiently sensitive measures to distinguish between healthy horses and horses with RAO in remission. To optimize the ability of volumetric capnography indices to differentiate among horses in heterogeneous populations, it is important to account for effects of age and specific use of the horses.  相似文献   

4.
Thirteen healthy neonatal Holstein calves were cold stressed twice by hosing with cold water for 20 minutes, 12 hours between hosings. Measurements of the pattern of ventilation [tidal volume (VT), respiratory frequency (f), minute ventilation (VMIN), and functional residual capacity (FRC)], gas exchange properties of the lungs [alveolar ventilation (VA), oxygen uptake (VO2), CO2 production (VCO2), dead space ventilation (VD), dead space/tidal volume ratio (VD/VT), arterial oxygen tension (PaO2), arterial CO2 tension (PaCO2) and alveolar-arterial oxygen difference (AaDO2)] and of the mechanical properties of the pulmonary system [dynamic compliance (Cdyn), pulmonary resistance (RL), and total respiratory system resistance (RRS)] were taken. Calves responded to chilling by increasing VO2 and VCO2 necessitating an increase in VA. This was accomplished by increasing VT with reciprocal decreases in f so that VMIN remained constant. There was no change in Cdyn, RL, or AaDO2. Seven of these 13 calves were then exposed to intratracheal inoculation of 2 X 10(9) organisms of Pasteurella haemolytica, the remaining calves serving as controls. Within 1 hour, calves exposed to P haemolytica had increased VMIN, f, VD/VT, and VD. There was a decrease in PaO2 associated with increased AaDO2, but no change in PaCO2, Cdyn or RL. By 3 hours after inoculation, there were pronounced changes in PaO2 and AaDO2, and Cdyn was reduced below base-line values. By 12 hours after inoculation, calves infected with P haemolytica had increased RL and RRS and PaCO2, in addition to the previously mentioned changes. Data from Pasteurella-exposed calves indicate that gas exchange impairment and peripheral lung injury occur rapidly and that increases in airway resistance develop relatively late in the disease.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
The rate of rise of arterial partial pressure of carbon dioxide (PaCO2) was determined in 49 apneic halothane-anesthetized horses following controlled ventilation. Drugs given for induction of anesthesia did not affect the rapid rate of rise of PaCO2 during the first minute after controlled ventilation, the PaCO2 at 1 minute after controlled ventilation, or the PaCO2 at which spontaneous ventilation began. Horses given xylazine-ketamine for induction of anesthesia had a significantly (P less than 0.05) faster rate of rise of PaCO2 after 1 minute following controlled ventilation than did horses receiving xylazine-thiamylal for induction.  相似文献   

6.
The objective of this study was to determine the accuracy with which pulmonary function indices derived from the volumetric capnogram can diagnose different degrees of recurrent airway obstruction (RAO) in 63 warmblood horses. The sensitivity, specificity, the area under the receiver operating curve (AUC), optimal cut-off values and predictive values of the indices were calculated. The results obtained have shown that there is no single index characterised by specificity and sensitivity to differentiate with an accuracy of >90 per cent between the different degrees of RAO compared to the clinical examination. The indices A(1)/A(2) and VD(alv)/ VT(alv) (AUC=0.55 and 0.53) appeared to have the highest relative sensitivity and specificity to differentiate between healthy horses and horses suffering from subclinical or minor RAO and the indices VD(phys)/ VT and VD(Bohr)/ VT between horses suffering from subclinical or minor RAO and horses with moderate to severe RAO (AUC=0.71 and 0.70). We do not consider it acceptable to use cut off values optimised for both maximal sensitivity and specificity, because a great number of horses would have been inappropriately classified.  相似文献   

7.
Anesthesia of equids is associated with pulmonary dysfunction. Cardiovascular and respiratory effects of inhalation anesthetic agents and duration of anesthesia have been studied, using oxygen as the carrier gas. To our knowledge, the effects of inspired oxygen have not been determined. We studied the cardiovascular and respiratory effects of 2 inspired oxygen fractions (0.30 and greater than 0.85) in 5 laterally recumbent, halothane-anesthetized horses. Mean systemic arterial blood pressure, cardiac output, central venous pressure, pulmonary arterial pressure, arterial pH, and arterial base excess were similar in horses of the 2 groups during 4 hours of anesthesia at constant end-tidal halothane concentration. End-tidal partial pressure of CO2, arterial partial pressure of CO2 and O2, and alveolar-to-arterial O2 tension difference were greater in horses exposed to the higher oxygen concentration. On the basis of the data obtained, we suggest that greater hypoventilation and ventilation/perfusion mismatch occur when horses are breathing high-oxygen fraction. Arterial partial pressure of O2 was not different between the 2 groups of horses after they were disconnected from the anesthesia circuit and allowed to breathe room air. Horses recovered from anesthesia without complications.  相似文献   

8.
Cardiovascular and respiratory functions were serially evaluated in ten healthy, fasting, spontaneously breathing, laterally recumbent adult horses during five hours of constant 1.06% alveolar halothane (equivalent to 1.2 times the minimum alveolar concentration for horses). Mean carotid arterial pressure was about 25% higher after one hour of constant-dose halothane than after 30 minutes of constant-dose (P less than 0.05), and remained increased throughout the study. Mean carotid arterial pressure peaked after 90 minutes, and was about 30% higher than at 30 minutes. Total peripheral vascular resistance initially increased (20% at one hour), then gradually returned to the 0.5-hour value over the next four hours. Cardiac output progressively increased with time (P less than 0.05; 20% by two hours; nearly 40% by five hours) because of an increase in stroke volume. An increase (P less than 0.05) in mixed venous PO2 accompanied the increase in cardiac output. Heart rate did not change significantly (P greater than 0.05). Some measures of ventilation changed significantly with time (P less than 0.05). After four and five hours of constant alveolar halothane, the PaCO2, inspired gas flow, and ratio of inspired vs expired gas flow were significantly higher than the 0.5-hour values. Inspiratory time significantly decreased, beginning at three hours. All horses recovered from anesthesia and recumbency without complications.  相似文献   

9.
Measurements of jejunal, ileal, and large colon (pelvic flexure) surface O2 tension (PSO2) were made in halothane-anesthetized horses with a nonheated miniature oxygen polarographic electrode. Assisted ventilation with 100% O2 was used to maintain PaCO2 tension at 50 +/- 8 mm of Hg while mean arterial blood pressure was maintained greater than or equal to 70 mm of Hg. Mean +/- SD PSO2 for the intestinal segments were: jejunum (horses 1 to 4), 71 +/- 20 mm of Hg; ileum (horses 1 to 4), 61 +/- 8 mm of Hg; and pelvic flexure of the large colon (horses 1 to 10), 55 +/- 13 mm of Hg. The response of the sensor to intestinal ischemia was studied in the large colon of an additional 12 halothane-anesthetized horses, using 4 types of vascular occlusion: venous (4 horses); arterial and venous (4 horses); venous and intramural vascular obstruction (2 horses); and arterial, venous, and intramural obstruction (2 horses). Venous and arterial occlusions were maintained for 30, 60, 90, and 120 minutes, whereas intramural obstruction combined with either type of vascular obstruction was studied for 60 to 120 minutes. After vascular occlusion, PSO2 decreased to 8 +/- 7 mm of Hg for venous obstruction, 4 +/- 3 mm of Hg for arterial and venous obstruction, 6 +/- 0 mm of Hg for intramural and venous obstruction, and 3 +/- 0 mm of Hg after intramural and arterial and venous obstruction. Thirty minutes after release of the clamps, the PSO2 increased to greater than or equal to 50% of the preoccluded large colon value.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
Ventilation and gas exchange were studied in healthy, adult horses and cows, two large species with different lung structures and different breathing patterns. The oxygen uptake (VO2), carbon dioxide output (VCO2), respiratory rate (fR), minute ventilation (VE), alveolar ventilation (VA), alveolar oxygen pressure (PAO2), and VE/VO2 ratio were higher in the cows, while the tidal volume (VT) and physiological dead space (VD) were larger in the horses. The arterial blood gases, alveolar-arterial oxygen pressure difference (PAO2-PaO2) and VD/VT ratio did not differ between the two species. The higher VO2 in the cows was most likely due to the energy cost of standing, and possibly to a higher cost of digestion. The higher VE, VA, VE/VO2 and PAO2 were most likely secondary to the increased VO2 and the slightly higher respiratory exchange ratio (R) in the cows. In contrast to hypotheses based on allometric equations, the PAO2 of horses and cows did not appear to differ from that of smaller mammals. The VD was larger than that predicted from allometric equations, and even though the VD/VT ratio (0.50) was lower than the previously reported values for horses and cows, it was significantly larger than the predicted weight-independent value of 0.36. Re-examination of the data used to derive the equation for VD raised questions as to the validity of this equation, and it is suggested that caution be exercised in the use of allometric equations for prediction.  相似文献   

11.
Cardiovascular and respiratory responses to variable PaO2 were measured in 6 horses anesthetized only with halothane during spontaneous (SV) and controlled (CV) ventilation. The minimal alveolar concentration (MAC) for halothane in oxygen was determined in each spontaneously breathing horse prior to establishing PaO2 study conditions--mean +/- SEM, 0.95 +/- 0.03 vol%. The PaO2 conditions of > 250, 120, 80, and 50 mm of Hg were studied in each horse anesthetized at 1.2 MAC of halothane and positioned in left lateral recumbency. In response to a decrease in PaO2, total peripheral resistance and systolic and diastolic arterial blood pressure decreased (P < 0.05) during SV. Cardiac output tended to increase because heart rate increased (P < 0.05) during these same conditions. During CV, cardiovascular function was usually less than it was at comparable PaO2 during SV (P < 0.05). Heart rate, cardiac output, and left ventricular work increased (P < 0.05) in response to a decrease in PaO2, whereas total peripheral resistance decreased (P < 0.05). During SV, cardiac output and stroke volume increased and arterial blood pressure and total peripheral resistance decreased with duration of anesthesia at PaO2 > 250 mm of Hg. During SV, minute expired volume increased (P < 0.05) because respiratory frequency tended to increase as PaO2 decreased. Decrease in PaCO2 (P < 0.05) also accompanied these respiratory changes. Although oxygen utilization was nearly constant over all treatment periods, oxygen delivery decreased (P < 0.05) with decrease in PaO2, and was less (P < 0.05) during CV, compared with SV, for comparable PaO2 values.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

12.
OBJECTIVE: To determine whether high intracranial pressure (ICP) during spontaneous ventilation (SV) in anesthetized horses coincides with an increase in intracranial elastance (ie, change in ICP per unit change of intracranial volume). ANIMALS: 6 adult horses. PROCEDURE: Anesthesia was induced and maintained in each horse for 5 hours with isoflurane at a constant dose equal to 1.2 times the minimum alveolar concentration. Direct ICP measurements were obtained by use of a strain gauge transducer inserted in the subarachnoid space, and arterial blood pressure was measured from a carotid artery. Physiologic responses were recorded after 15 minutes of normocapnic controlled ventilation (CV) and then after 10 minutes of SV. Aliquots (3 mL) of CSF were removed from each horse during SV until ICP returned to CV values. Slopes of pressure-volume curves yielded intracranial elastance. RESULTS: Intracranial elastance ranged from 0.2 to 3.7 mm Hg/mL after removal of the first aliquot of CSF Slopes of pressure-volume curves were largest following removal of the initial CSF aliquot, but shallow portions of curves were detected at relatively high ICPs (25 to 35 mm Hg). A second-order relationship between SV ICP and initial intracranial elastance was found. CONCLUSIONS AND CLINICAL RELEVANCE: In horses anesthetized with isoflurane, small changes in intracranial volume can cause large changes in ICP Increased intracranial elastance could further exacerbate preexisting intracranial hypertension. However, removal of small volumes of CSF may cause rapid compensatory replacement from other intracranial compartments, which suggests steady-state maintenance of an increase in intracranial volume during isoflurane anesthesia in horses.  相似文献   

13.
The effects of different arterial carbon dioxide tensions (PaCO2) on cerebrospinal fluid pressure (CSFP) and intraocular pressure (IOP) were studied in 6 male halothane-anesthetized horses positioned in left lateral recumbency. Steady-state anesthetic conditions (1.06% end-tidal halothane concentration) commenced 60 minutes following anesthetic induction with only halothane in oxygen. During atracurium neuromuscular blockade, horses were ventilated, and respiratory rate and peak inspiratory airway pressure were maintained within narrow limits. The CSFP and IOP were measured at 3 different levels of PaCO2 (approx 40, 60, and 80 mm of Hg). The PaCO2 sequence in each horse was determined from a type of switchback design with the initial PaCO2 (period 1), established 30 minutes after the commencement of steady-state anesthesia, being repeated in the middle (period 3) and again at the end (period 5) of the experiment. Measurements taken from the middle 3 periods (2, 3, and 4) would form a Latin square design replicated twice. The interval between each period was approximately 45 minutes. Data from periods 2, 3, and 4 indicated that CSFP (P less than 0.05) and mean systemic arterial pressure increased significantly (P less than 0.05) with high PaCO2. Mean central venous pressure, heart rate, and IOP did not change significantly during these same conditions. Measurements taken during periods 1, 3, and 5 were compared to assess the time-related responses to anesthesia and showed a significant increase in CSFP, a significant decrease in mean central venous pressure, and a small (but not statistically significant) increase in mean systemic arterial pressure.  相似文献   

14.
Hemodynamic and respiratory effects of 5 h of unvarying 1.57%, end-tidal (1.2 MAC) isoflurane in O2 anesthesia were characterized in ten left laterally recumbent horses. Compared to base line values at 30 min of constant dose isoflurane, cardiac output, hematocrit, total plasma solids, PaCO2, and peak inspired gas flow progressively and significantly (P less than 0.05) increased over the course of study. Arterial blood pressure increased (P less than 0.05) during the first 2 h of constant dose of isoflurane then decreased and remained near base line values. Inspiratory time progressively decreased with time of anesthesia. All horses recovered from anesthesia uneventfully within 1 h of termination of isoflurane.  相似文献   

15.
The correlation between end-tidal partial pressure of CO2 (PETCO2) and arterial PCO2 (PaCO2) was studied in six halothane-anesthetized dogs maintained under four different ventilatory regimens: (A) spontaneous breathing; (B) assisted positive-pressure ventilation; (C) intermittent manual inflation; and (D) ventilator-controlled breathing. For procedures A, B, and D together, there was a strong correlation between PETCO2 and PaCO2 (r = 0.8) that was highly significant at P less than 0.0001 for PETCO2 values between 31.3 and 61 mm of Hg. In spontaneous and controlled breathing, PETCO2 is representative of PaCO2 and provides a useful noninvasive tool for monitoring the patient maintained under general anesthesia. Furthermore, data suggest that any ventilatory support of the anesthetized patient markedly improves blood gas and acid-base status compared with that of the unsupported, spontaneously breathing animal.  相似文献   

16.
The purpose of this study was to determine the effects of low-flow ischemia and reperfusion (I-R) of the large colon on 16 systemic venous (SV) and colonic venous (CV) plasma biochemical variables in horses. Horses (n = 24) were randomly allocated to 3 groups: sham-operated (n = 6), 6 h ischemia (n = 9), and 3 h ischemia followed by 3 h reperfusion (n = 9). SV and CV heparinized blood was collected at 0, 1, 3, 3.25, 4, and 6 h. The SV-CV difference was calculated for each variable. The SV, CV, and SV-CV difference for albumin, total protein, and calcium decreased significantly (P < 0.05) across time in horses of all groups, but there were no differences among groups. SV phosphorous was significantly increased from baseline (BL) at 1 to 6 h in horses of all groups, but there were no differences among groups. CV phosphorous was significantly greater than BL from 1 to 6 h in group-2 horses and from 1 to 3 h in group-3 horses. SV potassium was not different among groups, but was significantly higher at 6 h, compared with BL in horses of all groups. CV potassium was significantly greater than BL from 1 to 6 h in horses of groups 2 and 3. SV glucose was greater at 6 h compared with all previous times in horses of all groups, but there were no difference among groups. CV glucose was significantly lower than BL and group-1 values in horses of groups 2 and 3 during ischemia, but returned to BL during reperfusion in group-3 horses. CV anion gap was significantly greater and SV-CV anion gap was significantly more negative in horses of groups 2 and 3, compared with group-1 horses during ischemia. The biologic relevance of these alterations is unknown, but they may contribute to histopathologic, hemodynamic, and metabolic alterations characteristic of low-flow I-R. Alternatively, these alterations may simply reflect colonic injury sustained during I-R. Results suggest that the colon utilizes glucose as a fuel and generates acid anions during low-flow ischemia. Increased CV phosphorous and potassium during I-R likely occurs as a result of leakage of intracellular stores subsequent to cellular damage.  相似文献   

17.
The correlation between end-tidal partial pressure of CO2 (PETCO2) and arterial (PaCO2) was determined for spontaneously breathing ponies under halothane or isoflurane anesthesia. The PETCO2 was useful as a trend indicator of PaCO2 during the first 60 minutes of halothane or isoflurane anesthesia when PaCO2 values were less than 60 to 70 mm of Hg. Halothane anesthesia lasting greater than 90 minutes was associated with PaCO2 values in excess of 60 to 70 mm of Hg, a large arterial- to end-tidal PCO2 difference (PaCO2-PETCO2) and a significant increase in alveolar dead space. These effects were not seen during the same period of isoflurane anesthesia. Arterial blood gas analysis is therefore recommended during halothane anesthesia when the PETCO2 is greater than 60 to 70 mm of Hg. A decrease in alveolar capillary perfusion relative to alveolar ventilation is the most likely cause for the increase in alveolar dead space during halothane anesthesia. Based on these findings, isoflurane may be superior to halothane for prolonged anesthesia of spontaneously breathing horses.  相似文献   

18.
BACKGROUND: Hypertonic saline and hydroxyethyl starches have been proposed as alternatives to isotonic crystalloids for reversal of hypovolemia in horses with colic. However, no direct comparison of these fluids has been performed in a clinical setting. HYPOTHESIS: Preoperative administration of hypertonic saline or pentastarch would produce similar effects on intra operative hemodynamics in horses with colic. ANIMALS: Thirty horses requiring colic surgery were enrolled in this prospective, randomized, open-label clinical trial. Inclusion criteria were owner consent, and at least 2 of 3 clinicopathologic abnormalities: packed cell volume >45%, plasma total solid concentration >8.0 g/dL, and blood lactate concentration >2.5 mM. METHODS: Study horses were randomly assigned to receive 4 mL/kg hypertonic saline or pentastarch before induction of anesthesia. Hemodynamic measurements were recorded every 30 minutes during anesthesia. Cardiac output (CO) was measured by the lithium dilution method. CO and stroke volume (SV) were indexed by body weight. Data were analysed using repeated measures analysis of variance (ANOVA). Post hoc comparisons were performed using the Bonferroni test. RESULTS: Cardiac index (CI) was higher in the pentastarch group compared with the hypertonic saline group from 30 to 150 minutes after induction (P = .04). SV index was higher in the pentastarch group at 30 (P = .025) and 60 minutes (P = .04). Mean arterial pressure of horses in both groups was lower at 90 minutes compared with 30 and 60 minutes. CONCLUSIONS AND CLINICAL IMPORTANCE: Preoperative administration of pentastarch results in better CI than hypertonic saline, for 150 minutes after anesthetic induction. The effect of this improved global blood flow on regional perfusion or clinical outcome remains to be elucidated.  相似文献   

19.
OBJECTIVE: To determine the disposition of lidocaine after IV infusion in anesthetized horses undergoing exploratory laparotomy because of gastrointestinal tract disease. ANIMALS: 11 horses (mean +/- SD, 10.3 +/- 7.4 years; 526 +/- 40 kg). PROCEDURE: Lidocaine hydrochloride (loading infusion, 1.3 mg/kg during a 15-minute period [87.5 microg/kg/min]; maintenance infusion, 50 microg/kg/min for 60 to 90 minutes) was administered IV to dorsally recumbent anesthetized horses. Blood samples were collected before and at fixed time points during and after lidocaine infusion for analysis of serum drug concentrations by use of liquid chromatography-mass spectrometry. Serum lidocaine concentrations were evaluated by use of standard noncompartmental analysis. Selected cardiopulmonary variables, including heart rate (HR), mean arterial pressure (MAP), arterial pH, PaCO2, and PaO2, were recorded. Recovery quality was assessed and recorded. RESULTS: Serum lidocaine concentrations paralleled administration, increasing rapidly with the initiation of the loading infusion and decreasing rapidly following discontinuation of the maintenance infusion. Mean +/- SD volume of distribution at steady state, total body clearance, and terminal half-life were 0.70 +/- 0.39 L/kg, 25 +/- 3 mL/kg/min, and 65 +/- 33 minutes, respectively. Cardiopulmonary variables were within reference ranges for horses anesthetized with inhalation anesthetics. Mean HR ranged from 36 +/- 1 beats/min to 43 +/- 9 beats/min, and mean MAP ranged from 74 +/- 18 mm Hg to 89 +/- 10 mm Hg. Recovery quality ranged from poor to excellent. CONCLUSIONS AND CLINICAL RELEVANCE: Availability of pharmacokinetic data for horses with gastrointestinal tract disease will facilitate appropriate clinical dosing of lidocaine.  相似文献   

20.
ObjectiveTo determine the haemodynamic effects of halothane and isoflurane with spontaneous and controlled ventilation in dorsally recumbent horses undergoing elective surgery.Study designProspective randomized clinical trial.AnimalsTwenty-five adult horses, body mass 487 kg (range: 267–690).MethodsHorses undergoing elective surgery in dorsal recumbency were randomly assigned to one of four treatment groups, isoflurane (I) or halothane (H) anaesthesia, each with spontaneous (SB) or controlled ventilation (IPPV). Indices of cardiac function and femoral arterial blood flow (ABF) and resistance were measured using transoesophageal and transcutaneous Doppler echocardiography, respectively. Arterial blood pressure was measured directly.ResultsFour horses assigned to receive isoflurane and spontaneous ventilation (SBI) required IPPV, leaving only three groups for analysis: SBH, IPPVH and IPPVI. Two horses were excluded from the halothane groups because dobutamine was infused to maintain arterial blood pressure. Cardiac index (CI) was significantly greater, and pre-ejection period (PEP) shorter, during isoflurane compared with halothane anaesthesia with both spontaneous (p = 0.04, p = 0.0006, respectively) or controlled ventilation (p = 0.04, p = 0.008, respectively). There was an association between CI and PaCO2 (p = 0.04) such that CI increased by 0.45 L minute−1m−2 for every kPa increase in PaCO2. Femoral ABF was only significantly higher during isoflurane compared with halothane anaesthesia during IPPV (p = 0.0006). There was a significant temporal decrease in CI, but not femoral arterial flow.ConclusionThe previously reported superior cardiovascular function during isoflurane compared with halothane anaesthesia was maintained in horses undergoing surgery. However, in these clinical subjects, a progressive decrease in CI, which was independent of ventilatory mode, was observed with both anaesthetic agents.Clinical relevanceCardiovascular function may deteriorate progressively in horses anaesthetized for brief (<2 hours) surgical procedures in dorsal recumbency. Although cardiovascular function is superior with isoflurane in dorsally recumbent horses, the need for IPPV may be greater.  相似文献   

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