Effects of acetylpromazine on ventilatory variables in the horse.

The influence of breathing various concentrations of carbon dioxide and oxygen upon minute volume, tidal volume, and respiratory rate were examined in acetylpromazine-tranquilized horses. Responses in the horses before (control period) and after tranquilization were qualitatively similar to increases in carbon dioxide and to alterations in oxygen. The quantitative responses to these changes were less in tranquilized horses than in the same horses studied in the untranquilized state. Tranquilization had its most prominent effect upon respiratory rate in horses breathing room air.     

Cardiorespiratory effects of isoflurane anesthesia in crested caracaras (Caracara plancus)

To evaluate the cardiorespiratory changes induced by isoflurane (ISO) anesthesia in the crested caracara (Caracara plancus), eight crested caracaras that weighed 1.0 kg (range 0.9-1.1 kg) were the subjects for the study. The birds were anesthetized by face mask with ISO for brachial artery catheterization. After recovery, anesthesia was re-induced and maintained with ISO with spontaneous ventilation. Electrocardiography, direct systolic arterial blood pressure (SAP), diastolic arterial blood pressure (DAP), mean arterial blood pressure (MAP), respiratory rate (RR), end-tidal carbon dioxide (P(ET)CO2), and cloacal temperature (T degrees C) were measured before induction (baseline, under physical restraint) and after 5, 10, 15, 20, 25, 30, 35, and 40 min of ISO anesthesia. Arterial blood samples were collected for blood gas analysis at baseline, 10, 25, and 40 min. No cardiac arrhythmias were observed in the present study. RR, SAP, DAP, MAP, T degrees C and pH decreased from baseline values, whereas arterial partial pressures of oxygen and carbon dioxide, bicarbonate concentration, and P(ET)CO2 were significantly higher than baseline. Apnea was not observed in any bird. ISO anesthesia is suitable for use in healthy members of this species despite the moderate cardiovascular and respiratory depression produced.     

Cardiopulmonary effects of using carbon dioxide for laparoscopic surgery in cats

The cardiopulmonary effects of capnoperitoneum were investigated in 8 spontaneously breathing, young adult female cats undergoing laparoscopic pancreatic biopsy (intra-abdominal pressure 12 mmHg). Cats were premedicated with acepromazine and hydromorphone, induced with ketamine and diazepam, and maintained using an end-tidal isoflurane concentration of 1.13% in 100% oxygen. Direct systemic arterial blood pressure, heart and respiratory rates, end-tidal carbon dioxide (CO(2)), and isoflurane were recorded every 5 min before insufflation (baseline), during insufflation of the abdomen with CO(2), and following desufflation. Arterial blood samples were drawn at baseline, at 10 and 30 min of insufflation, and 5 min after desufflation for blood gases. The significant findings (P < 0.05) were as follows: insufflation produced an increase in heart rate (5 to 15 min and at 30 min), mean arterial blood pressure (25 to 30 min), and diastolic arterial blood pressure (10 to 30 min). After desufflation, respiratory rate increased for 15 min. The changes were within physiologically acceptable limits in these healthy, anesthetized cats despite no artificial maintenance of minute ventilation.     

猪安氟醚麻醉时血气变化的研究

研究了猪在不同浓度安氟醚麻醉时血气的变化，结果显示：随着吸入浓度的升高，呼吸频率减慢，终末呼气二氧化碳分压（ＰcｔＣＯ_２）、动脉血二氧化碳分压（ＰａＣｏ_２）和二氧化碳总量（ＴＣＯ_２）明显上升，碱超、标准碳酸氢盐和动脉血氧分压无明显变化。经相关分析，ＰｃｔＣＯ_２与ＰａＣＯ_２呈显著正相关（ｒ＝０．９８７０），并可用ＰｃｔＣＯ_２判断麻醉深度。     

Evaluation of carbon dioxide anaesthesia for the castration of male suckling piglets by stress hormone concentrations, behaviour and clinical factors

The objective of this study was to examine the effect of an anaesthesia using 70% carbon dioxide and 30% oxygen on endocrine stress reaction, behaviour and clinical parameters of male suckling piglets during castration. One hundred and seventy one male piglets, three to five days of age, were allocated to two experiments. They were assigned either to the procedures control handling, control castration, handling under anaesthesia or castration under anaesthesia in each experiment. In Experiment 1, adrenaline and noradrenaline plasma concentrations were measured in blood samples taken before (-15 min) and after (immediately, 2 min) handling/castration. In Experiment 2, behavioural observations and clinical parameters such as heart and respiratory rate, oxygen saturation, reflexes and recovery time were assessed at several sampling times. Measurement of adrenaline and noradrenaline concentrations revealed an increase in all groups after handling/castration (p < 0.0167), but higher concentrations were seen in the anaesthetized groups (25 to 93 times) than in control groups (two to four times). The excessive endocrine reaction suggests that carbon dioxide inhalation causes a more stressful situation in piglets compared to castration without anaesthesia. Behavioural abnormalities, significant decreases in the heart rate, the respiratory rate and the oxygen saturation (p < or = 0.001) including a cardiac arrhythmia (extrasystoles) underline the impression that CO2 inhalation anaesthesia negatively affects animal welfare. Based on the results of this study, this anaesthetic method is unsuitable to reduce stress induced by castration. Further research on alternatives is necessary to ensure the well-being of the piglets during castration.     

Influence of the neuroleptanalgesic combination of etorphine and acepromazine on the horse: blood gases and acid-base balance.

Respiratory function and acid-base variables were studied in Welsh Mountain ponies before and at predetermined times after the intravenous injection of Immobilon and Revivon.A marked depression of respiratory rate was accompanied by large reductions in arterial blood oxygen tension and saturation and the development of a mild respiratory acidosis following the injection of Immobilon. It was concluded that at least three factors contributed to the hypoxic hypoxia produced by Immobilon; the posture of lateral recumbency, the decrease in respiratory rate and the laboured character of the respiration. Arterial oxygen and carbon dioxide tensions returned towards control levels soon after administering Revivon. Mixed venous oxygen tensions were little affected by either Immobilon or Revivon, and mixed venous carbon dioxide tensions were increased to smaller degrees that those of arterial blood. Haemoglobin was increased initially by Immobilon, had returned to the control level by 30 min and fell below the control following the administration of Revivon.     

Influence of modified open lung concept ventilation on the cardiovascular and pulmonary function of horses during total intravenous anaesthesia

The influence of a modified open lung concept (mOLC) on pulmonary and cardiovascular function during total intravenous anaesthesia (TIVA) in horses was evaluated. Forty-two warmblood horses (American Society of Anesthesiologists class 1 to 2), scheduled for elective surgery (mean [sd] weight 526 [65] kg, age 6.4 [5.4] years) were randomly divided into three groups: ventilation with mOLC, intermittent positive-pressure ventilation (IPPV), and spontaneous breathing. Premedication (0.8 mg/kg xylazine), induction (2.2 mg/kg ketamine and 0.05 mg/kg diazepam) and maintenance of anaesthesia with TIVA (1.4 mg/kg/hour xylazine, 5.6 mg/kg/hour ketamine and 131.1 mg/kg/hour guaifenesin), with inhalation of 35 per cent oxygen in air, were identical in all horses. Heart rate, respiratory rate, mean arterial blood pressure (MAP), pH, and arterial partial pressure of oxygen (p(a)O(2)) and carbon dioxide (p(a)CO(2)) were evaluated. Data were collected every 10 minutes from 20 to 90 minutes anaesthesia time. Factorial analysis of variance and Tukey's post hoc test were used for statistical analysis (a=5 per cent). Horses in the mOLC-ventilated group had an overall significantly higher p(a)O(2) (16.9 [1.0] v 11.7 [1.34] v 10.5 [0.57] kPa) and lower MAP (93.1 [5.47] v 107.1 [6.99] v 101.2 [5.45] mmHg) than the IPPV and spontaneously breathing groups, respectively.     

Effect of intranasal oxygen administration on blood gas variables and outcome in neonatal calves with respiratory distress syndrome: 20 cases (2004-2006)

OBJECTIVE: To determine the effect of intranasal oxygen administration on blood gas variables and outcome in neonatal calves with respiratory distress syndrome (RDS). DESIGN: Retrospective case series. ANIMALS: 20 neonatal calves with RDS. PROCEDURES: Arterial partial pressure of oxygen (PaO(2)), arterial partial pressure of carbon dioxide, and arterial oxygen saturation (SaO(2)) before and after intranasal administration of oxygen were analyzed. RESULTS: There were significant increases in PaO(2) and SaO(2) in the first 24 hours after oxygen administration was begun, with mean +/- SD PaO(2) increasing from 38.4+/-8.8 mm Hg to 58.7+/-17.8 mm Hg during the first 3 hours of treatment. Calves with PaO(2)>55 mm Hg within the first 12 hours after oxygen administration was begun had a significantly higher survival rate (9/10) than did calves that did not reach this threshold (4/10). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that intranasal oxygen administration was a simple method of improving blood gas variables in neonatal calves with RDS and that PaO(2) could be used to predict outcome.     

不同CO2气腹压对小型猪循环系统的影响

选择30只健康小型猪随机分为A、B、C、D、E等5组。分别以0、0．8、1．06、1．33、1．6kPa的气腹压进行充气腹试验，以探讨不同CO2气腹压对小型猪循环系统的影响。结果显示，A组试验猪血压和心率持续降低。B、C、D、E组试验猪会引起血压和心率的升高。本试验确定了不同气腹压对小型猪循环系统的影响程度是E组〉D组〉C组〉B组。因此，在小型猪腹腔镜手术充气腹时，选用1.33kPa气腹压值对循环系统的影响较小，同时能保证小型猪腹腔的充分膨胀隆起，便于手术操作，从而为今后开展小型猪腹腔镜手术奠定了理论基础。     

Chemical immobilization of rhebok (Pelea capreolus) with carfentanil-xylazine or etorphine-xylazine.

Twelve adult rhebok (Pelea capreolus) were immobilized using a combination of 0.4 mg/kg xylazine and either 0.01 mg/kg of carfentanil (n = 6) or 0.01 mg/kg etorphine (n = 6), delivered i.m. using a remote injection system. Induction and recovery times, heart rate, respiratory rate, rectal temperature, oxygen saturation, end-tidal CO2 (ETCO2), anesthetic depth, indirect blood pressure, and arterial blood gases were recorded. Rhebok were not intubated but nasal oxygen was administered. Forty minutes after induction, anesthesia was antagonized with naltrexone and yohimbine. Mean initial heart rate was significantly higher in the carfentanil group than in the etorphine group. Mean initial oxygen saturation was consistent with hypoxia in both the carfentanil group and the etorphine group. In both groups, arterial pH decreased and partial pressure of carbon dioxide increased during the first 15 min of anesthesia, and values were similar in both groups. These findings were consistent with respiratory acidosis and decreased ventilation. Values for respiratory rate, temperature, oxygen saturation, ETCO2, and blood pressure were similar for both groups at all time periods. During the first 5 min of anesthesia, rhebok in the carfentanil group were more responsive to stimuli than rhebok in the etorphine group. After administration of antagonists, time to first arousal was significantly shorter in the etorphine group than in the carfentanil group. Although cardiopulmonary values were similar for the two groups, rhebok in the carfentanil group were at a comparatively lighter plane of anesthesia, and some individuals in this group required additional manual and chemical restraint for medical procedures to be performed. In conclusion, for captive adult rhebok, 0.01 mg/kg of etorphine and 0.4 mg/kg of xylazine are recommended over 0.01 mg/kg carfentanil and 0.4 mg/kg xylazine because of qualitatively better anesthetic episodes and shorter recovery times.     

The cardiorespiratory effects of morphine and butorphanol in horses anaesthetised under clinical conditions

Twenty-five horses admitted for minor orthopaedic or soft tissue surgery were anaesthetised with detomidine, ketamine and halothane. Heart rate, arterial blood pressure, respiratory rate, tidal volume, minute volume, blood gases and occlusion pressures were measured before and for 30 mins after intravenous (iv) injection of saline, butorphanol 0.05 mg/kg bodyweight (bwt) or morphine 0.02 or 0.05 mg/kg bwt. Drug or saline treatment induced no significant changes from pre-treatment values within a group for arterial blood pressure, heart rate, respiratory rate, arterial carbon dioxide tension, arterial oxygen tension and occlusion pressure. In conclusion, both morphine and butorphanol at the stated doses cause no adverse effects on the cardiovascular and respiratory systems of anaesthetised horses.     

The cardiopulmonary effects of dobutamine and norepinephrine in isoflurane-anesthetized foals

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.     

Respiratory responses of the domestic fowl to low level carbon dioxide exposure

Respiratory function in the restrained, conscious domestic fowl was measured using a non-invasive technique and computer aided analysis to examine respiratory flow, and in-dwelling arterial catheters to monitor blood carbon dioxide levels. The effects of two low ranges of inspiratory carbon dioxide (0.2 to 1.0 per cent and 0.25 to 2.25 per cent) were studied, simulating levels of carbon dioxide that may occur in commercial poultry units and representing a mild environmental stress for the birds. A linear increase in minute volume with inspiratory carbon dioxide was observed, due primarily to increases in tidal volume. Arterial carbon dioxide (PaCO2) tension also rose as the inspiratory carbon dioxide concentration was raised, but higher inspiratory carbon dioxide levels were required to affect significantly blood carbon dioxide concentration than to modify respiratory parameters. Variation was observed in the individual bird's response to carbon dioxide (bird X carbon dioxide interaction), suggesting that resting values of the respiratory parameters measured were important in determining the bird's ventilatory response to carbon dioxide.     

Assessment of the respiratory actions of intramuscular morphine in conscious dogs.

The actions on the respiratory system of 0.25, 0.5 and 1.0 mg kg(-1) morphine given intramuscularly were studied in conscious dogs. Dogs breathed oxygen with 0, 2 and 4 per cent CO(2), in that order, through a mask attached to a flow sensor and connected to a respiratory mechanics monitor. When a steady state period of respiration was reached breathing pure oxygen, respiratory rate, tidal volume, respiratory minute volume, peak expiratory flow rate and end tidal CO(2)(PetCO(2)) were measured. The respiratory minute volume and PetCO(2) were measured when the dogs breathed 2 and 4 per cent CO(2) in oxygen, the points plotted onto a graph and the gradient of the line, describing the PCO(2)/ventilation response, plus the intercept with the y-axis were determined. Measurements for each morphine dose were taken before injection and at 30 minutes, 1, 2, 3, 4, 6 and 8 hours post injection.The incidence of panting after morphine was dose related and it occurred in all dogs given the high dose. Morphine reduced the gradients of the PCO(2)/ventilation response lines and raised the intercept. Other changes were increased respiratory minute volume and peak expiratory flow and decreased PetCO(2) and tidal volume.     

Blood oxygen and carbon dioxide tensions in normal dogs and in dogs with respiratory failure

Arterial blood samples were obtained from thirty normal conscious dogs breathing air. The mean values and standard deviations recorded were PaO₂ 101.3±5.6 mmHg, PaCO₂ 34.0±3.9 mmHg, oxygen saturation 93.8 ±1.2%, oxygen content 19.3 ± 1.8 ml/100 ml. Ten dogs with respiratory problems were also examined and of these animals seven had lower than normal oxygen tensions while three had carbon dioxide levels higher than those found in healthy dogs. It was concluded that, in severe respiratory disease, measurement of arterial oxygen tension gives a useful assessment of respiratory failure in dogs.     

Effect of a respiratory gas collection mask on some measurements of cardiovascular and respiratory function in horses exercising on a treadmill

The effects of a respiratory gas collection mask on arterial blood gases, acid base values, oxygen content, respiratory frequency and heart rate, were investigated in standardbred horses during treadmill exercise at speeds up to 10 m sec-1 and a treadmill slope of 10 per cent. The mask had no significant effect on heart rates during exercise, but respiratory frequency was lower when the mask was used. The increase in respiratory frequency as treadmill velocity increased was also significantly slower with the mask operative. Arterial carbon dioxide tensions were significantly higher during exercise with the mask than without, and arterial oxygen tension was significantly lower at the highest exercise intensity. Arterial oxygen content was significantly lower at all work speeds when the mask was used. There were minimal effects of the mask on arterial acid base values. It was concluded that a respiratory gas collection mask caused alveolar hypoventilation in exercising horses, but did not markedly influence heart rate or arterial acid base values during exercise.     

The effect of hyoscine on dobutamine requirement in spontaneously breathing horses anaesthetized with halothane

OBJECTIVE: To determine whether hyoscine has a sparing effect on the volume of dobutamine required to maintain mean arterial pressure (MAP) at 70 mmHg in horses anaesthetized with halothane. STUDY DESIGN: Prospective, randomized, controlled clinical trial. ANIMALS: Twenty adult horses weighing 507 +/- 97 kg (mean +/- SD), aged 10 +/- 5 years. MATERIALS AND METHODS: Pre-anaesthetic medication in all horses was intramuscular (IM) acepromazine (40 mug kg(-1)) and intravenous (IV) detomidine (0.02 mg kg(-1)). Anaesthesia was induced with ketamine (2.2 mg kg(-1) IV) and diazepam (0.02 mg kg(-1) IV), and maintained with halothane in oxygen. Horses breathed spontaneously. Flunixin (1.1 mg kg(-1) IV) was given to provide analgesia. Heart rate, ECG, invasive arterial pressure, respiratory rate, percentage end-tidal carbon dioxide, percentage end-tidal halothane and partial pressure of oxygen and carbon dioxide in arterial blood and blood pH were monitored. Dobutamine was infused by an infusion pump to maintain MAP at 70 mmHg. Horses were randomly assigned to receive saline or hyoscine (0.1 mg kg(-1)) IV 30 minutes after induction. The heart rate, MAP and volume of dobutamine infused over 30-minute periods were measured and analysed statistically using a one-way anova. RESULTS: After administration of hyoscine, heart rate increased for 10 minutes (p < 0.01) and MAP for 5 minutes (p < 0.01). There was no difference in the volume of dobutamine infused over 30 minutes between horses given hyoscine or saline, although there was a wide individual variation in dobutamine requirements. No side effects of hyoscine were seen. CONCLUSIONS: The increase in heart rate and blood pressure that occurs after 0.1 mg kg(-1) hyoscine is given IV in anaesthetized horses, is of short duration and does not significantly alter the amount of dobutamine required to maintain arterial pressure over the next 30 minutes. Clinical relevance The short duration of action of 0.1 mg kg(-1) hyoscine IV may limit its usefulness for correction of hypotension in horses anaesthetized with halothane. Further work is necessary to investigate the effects of higher or repeated doses or constant rate infusions of hyoscine.     

Comparison of noninvasive cardiac output measured by use of partial carbon dioxide rebreathing or the lithium dilution method in anesthetized foals

OBJECTIVE: To compare cardiac output (CO) measured by use of the partial carbon dioxide rebreathing method (NICO) or lithium dilution method (LiDCO) in anesthetized foals. SAMPLE POPULATION: Data reported in 2 other studies for 18 neonatal foals that weighed 32 to 61 kg. PROCEDURES: Foals were anesthetized and instrumented to measure direct blood pressure, heart rate, arterial blood gases, end-tidal isoflurane and carbon dioxide concentrations, and CO. Various COs were achieved by administration of dobutamine, norepinephrine, vasopressin, phenylephrine, and isoflurane to allow comparisons between LiDCO and NICO methods. Measurements were obtained in duplicate or triplicate. We allowed 2 minutes between measurements for LiDCO and 3 minutes for NICO after achieving a stable hemodynamic plane for at least 10 to 15 minutes at each CO. RESULTS: 217 comparisons were made. Correlation (r = 0.77) was good between the 2 methods for all determinations. Mean +/- SD measurements of cardiac index for all comparisons with the LiDCO and NICO methods were 138 +/- 62 mL/kg/min (range, 40 to 381 mL/kg/min) and 154 +/- 55 mL/kg/min (range, 54 to 358 mL/kg/min), respectively. Mean difference (bias) between LiDCO and NICO measurements was -17.3 mL/kg/min with a precision (1.96 x SD) of 114 mL/kg/min (range, -131.3 to 96.7). Mean of the differences of LiDCO and NICO measurements was 4.37 + (0.87 x NICO value). CONCLUSIONS AND CLINICAL RELEVANCE: The NICO method is a viable, noninvasive method for determination of CO in neonatal foals with normal respiratory function. It compares well with the more invasive LiDCO method.     

The effect of colic on oxygen extraction in horses

Blood oxygen transport and oxygen extraction were assessed in horses with colic. A gravity score (GS) ranging from 1 to 3 was attributed to each colic case with healthy horses used as controls. Jugular venous and carotid arterial blood samples were collected and concentrations of 2,3-diphosphoglycerate, adenosine triphosphate, inorganic phosphate and chloride were determined. pH and partial pressures of carbon dioxide (PCO(2)), and oxygen (PO(2)) were also measured. Oxygen equilibrium curves (OEC) were constructed under standard conditions and oxygen extraction ratios calculated. Haemoglobin oxygen affinity measured under standard conditions (P50(std)) was unchanged in colic horses compared with healthy controls. Horses with the highest GS, i.e. 3 had lower blood pH values than healthy animals. Arterial and venous partial pressures of oxygen at 50% haemoglobin saturation (P50(a) and P50(v)) were significantly higher in horses suffering from colic (GS=3) than in healthy horses. The oxygen extraction ratio was also significantly increased in colic horses with a GS of 3. A rise in the oxygen extraction ratio detected in the most severely affected animals seemed to reflect the compensatory properties of the oxygen transport system where extraction of oxygen from the blood increases when systemic oxygen delivery decreases, as might be anticipated in horses with colic.     

Analgesia in Dogs after Intercostal Thoracotomy A Comparison of Morphine, Selective Intercostal Nerve Block, and Interpleural Regional Analgesia with Bupivacaine

Three postoperative analgesic protocols were assigned randomly to 24 healthy dogs after thoracotomy at the left fourth intercostal space. Morphine was administered parenterally to eight dogs after tracheal extubation; selective intercostal nerve blocks with bupivacaine hydrochloride and epinephrine were administered to eight dogs before closure of the thorax; and bupivacaine hydrochloride and epinephrine were administered through an interpleural catheter to eight dogs after tracheal extubation. Heart rate, respiratory rate, rectal temperature, hematocrit, plasma protein, blood gas, and pain score evaluations were recorded before surgery and 30 minutes, 1 hour, 2 hours, and 3 hours after extubation. Morphine caused significant decreases in blood pH and blood oxygen tensions, and significant increases in carbon dioxide tensions. Dogs treated with intercostal nerve blocks had no significant changes in these parameters, and dogs treated with interpleural bupivacaine had significant decreases in blood oxygen tension. All dogs had significant decreases in rectal temperature, and hypothermia was prolonged after morphine. Analgesia was initially adequate in most dogs, but some dogs in each treatment group had recurrence of pain and were treated with interpleural bupivacaine. One dog developed pneumothorax. Interpleural administration of bupivacaine produced analgesia equal to that produced by systemic administration of morphine or selective intercostal nerve block with bupivacaine. Bupivacaine was easily readministered through an interpleural catheter. Respiratory compromise was less in dogs treated with bupivacaine than in dogs treated with morphine. After intercostal thoracotomy, interpleural bupivacaine provided prolonged analgesia with fewer blood gas alterations than morphine.