RESUMO
BACKGROUND: Cardiac output (CO) is an important haemodynamic parameter to monitor in patients during surgery. However, the majority of the techniques for measuring CO have a limited application in veterinary practice due to their invasive approach and associated complexity and risks. Transoesophageal echocardiography (TEE) is a technique used to monitor cardiac function in human patients during surgical procedures and allows CO to be measured non-invasively. This prospective clinical study aimed to compare the transoesophageal echocardiography using a transgastric view of the left ventricular outflow tract (LVOT) and the thermodilution (TD) technique for the assessment of CO during mean arterial pressure of 65-80 mmHg (normotension) and <65 mmHg (hypotension) in dogs undergoing elective surgery. Eight dogs were pre-medicated with acepromazine (0.05 mg/kg, IM), tramadol (4 mg/kg, IM) and atropine (0.03 mg/kg, IM), followed by anaesthetic induction with propofol (3-5 mg/kg IV) and maintenance with isoflurane associated with a continuous infusion rate of fentanyl (bolus of 3 µg/kg followed by 0.3 µg/kg/min). The CO was measured by TEE (COTEE) and TD (COTD) at the end of expiration during normotension and hypotension (induced by isoflurane). RESULTS: There was a strong positive correlation between COTEE and COTD ââ(r = 0.925; P < 0.0001). The bias between COTD and COTEE was 0.14 ± 0.29 L/min (limits of agreement, -0.44 to 0.72 L/min). The percentage error of CO measured by the two methods was 12.32%. In addition, a strong positive correlation was found between COTEE and COTD during normotension (r = 0.995; P < 0.0001) and hypotension (r = 0.78; P = 0.0223). CONCLUSIONS: The results of this study indicated that the transgastric view of the LVOT by TEE was a minimally invasive alternative to clinically monitoring CO in dogs during anaesthesia. However, during hypotension, the CO obtained by TEE was less reliable, although still acceptable.
Assuntos
Débito Cardíaco/fisiologia , Cães/fisiologia , Ecocardiografia Transesofagiana/veterinária , Termodiluição/veterinária , Anestesia/veterinária , Animais , Ecocardiografia Transesofagiana/métodos , Hipotensão/induzido quimicamente , Isoflurano/farmacologia , Monitorização Intraoperatória/métodos , Monitorização Intraoperatória/veterinária , Estudos Prospectivos , Reprodutibilidade dos Testes , Termodiluição/métodosRESUMO
OBJECTIVE: To investigate whether pulse pressure variation (PPV) can predict fluid responsiveness in healthy dogs during clinical surgery. STUDY DESIGN: Prospective clinical study. ANIMALS: Thirty-three isoflurane-anesthetized dogs with arterial hypotension during orthopedic surgery. METHODS: Fluid challenge with lactated Ringer's solution (15 mL kg-1 in 15 minutes) was administered in mechanically ventilated dogs (tidal volume 10 mL kg-1) with hypotension [mean arterial pressure (MAP) < 65 mmHg]. The volume expansion was considered effective if cardiac output (CO; transesophageal Doppler) increased by ≥ 15%. Cardiopulmonary data were analyzed using two-way ANOVA, receiver operating characteristics (ROC) curves and Spearman coefficient; p < 0.05 was considered significant. RESULTS: Effective volume expansion, mean ± standard deviation 42 ± 4% increase in CO (p < 0.0001) was observed in 76% of the dogs, resulting in a decrease in PPV (p < 0.0001) and increase in MAP (p < 0.0001), central venous pressure (CVP; p = 0.02) and ejection fraction (p < 0.0001) compared with before the fluid challenge. None of these changes occurred when volume expansion resulted in a nonsignificant CO increase of 4 ± 5%. No significant differences were observed in blood gas analysis between responsive and nonresponsive dogs. The increase in CO was correlated with the decrease in PPV (r = -0.65; p < 0.0001) but absolute values of CO and PPV were not correlated. The PPV performance (ROC curve area: 0.89 ± 0.06, p = 0.0011) was better than that of CVP (ROC curve area: 0.54 ± 0.12) and MAP (ROC curve area: 0.59 ± 0.13) to predict fluid responsiveness. The best cut-off for PPV to distinguish responders and nonresponders was 15% (50% sensitivity and 96% specificity). CONCLUSIONS AND CLINICAL RELEVANCE: In mechanically ventilated, healthy, isoflurane-anesthetized dogs, PPV predicted fluid responsiveness to volume expansion, and MAP and CVP did not show such applicability.
Assuntos
Doenças do Cão/cirurgia , Hidratação/veterinária , Procedimentos Ortopédicos/veterinária , Animais , Gasometria/veterinária , Pressão Sanguínea/fisiologia , Débito Cardíaco/fisiologia , Cães , Hemodinâmica , Respiração Artificial/veterinária , Equilíbrio HidroeletrolíticoRESUMO
OBJECTIVE: To examine the intrapulmonary gas distribution of low and high tidal volumes (VT) and to investigate whether this is altered by an alveolar recruitment maneuver (ARM) and 5 cmH2O positive end-expiratory pressure (PEEP) during anesthesia. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Fourteen client-owned bitches weighing 26 ± 7 kg undergoing elective ovariohysterectomy. METHODS: Isoflurane-anesthetized dogs in dorsal recumbency were ventilated with 0 cmH2O PEEP and pressure-controlled ventilation by adjusting the peak inspiratory pressure (PIP) to achieve a low (7 mL kg-1; n = 7) or a high (12 mL kg-1; n = 7) VT. Ninety minutes after induction (T90), an ARM (PIP 20 cmH2O for 10 seconds, twice with a 10 second interval) was performed followed by the application of 5 cmH2O PEEP for 35 minutes (RM35). The vertical (ventral=0%; dorsal=100%) and horizontal (right=0%; left=100%) center of ventilation (CoV), four regions of interest (ROI) (ventral, central-ventral, central-dorsal, dorsal) identified in electrical impedance tomography images, and cardiopulmonary data were analyzed using two-way repeated measures anova. RESULTS: The low VT was centered in more ventral (nondependent) areas compared with high VT at T90 (CoV: 38.8 ± 2.5% versus 44.6 ± 7.2%; p = 0.0325). The ARM and PEEP shifted the CoV towards dorsal (dependent) areas only during high VT (50.5 ± 7.9% versus 41.1 ± 2.8% during low VT, p = 0.0108), which was more distributed to the central-dorsal ROI compared with low VT (p = 0.0046). The horizontal CoV was centrally distributed and cardiovascular variables remained unchanged throughout regardless of the VT, ARM, and PEEP. CONCLUSIONS AND CLINICAL RELEVANCE: Both low and high VT were poorly distributed to dorsal dependent regions, where ventilation was improved following the current ARM and PEEP only during high VT. Studies on the role of high VT on pulmonary complications are required.
Assuntos
Anestésicos Inalatórios , Impedância Elétrica , Isoflurano , Respiração com Pressão Positiva/veterinária , Animais , Cães , Feminino , Respiração com Pressão Positiva/métodos , Estudos Prospectivos , Volume de Ventilação Pulmonar/fisiologia , Fatores de Tempo , Tomografia/métodos , Tomografia/veterináriaRESUMO
OBJECTIVE: To compare the effects of pressure controlled ventilation (PCV) with volume-controlled ventilation (VCV) on lung compliance, gas exchange, and hemodynamics in isoflurane-anesthetized dogs. DESIGN: Prospective randomized study. SETTING: Veterinary teaching hospital. ANIMALS: Forty client-owned bitches undergoing elective ovariohysterectomy. INTERVENTIONS: Dogs were randomly assigned to be ventilated with 100% oxygen using PCV (n = 20) or VCV (n = 20). The respiratory rate was 20/min and positive end-expiratory pressure (PEEP) was 5 cm H2 O, with a tidal volume of 10 mL/kg. Cardiac output (CO) was measured using thermodilution. Cardiopulmonary and blood gas data were obtained during spontaneous ventilation and after 30 (T30) and 60 minutes (T60) of controlled ventilation. MEASUREMENTS AND MAIN RESULTS: In dogs ventilated with PCV, at T30 and T60, PIP was lower (11.4 ± 1.9 and 11.1 ± 1.5 cm H2 O, respectively) and static compliance (CST ) was higher (51 ± 7 and 56 ± 6 mL/cm H2 O, respectively) than in VCV group (PIP of 14.3 ± 1.3 and 15.5 ± 1.4 cm H2 O; CST of 34 ± 8 and 33 ± 9 mL/cm H2 O, P < 0.0001). Compared with spontaneous ventilation, both groups had decreased alveolar-arterial oxygen difference at T30 and T60 (PCV: 128 ± 32 mm Hg vs 108 ± 20 and 104 ± 16 mm Hg, respectively; VCV: 131 ± 38 mm Hg vs 109 ± 19 and 107 ± 14 mm Hg, respectively; P < 0.01), while CO was maintained at all time points. CONCLUSIONS: Compared to spontaneous ventilation, both ventilatory modes effectively improved gas exchange without hemodynamic impairment. PCV resulted in higher lung CST and lower PIP compared to VCV.
Assuntos
Anestesia/veterinária , Débito Cardíaco/fisiologia , Cães/fisiologia , Complacência Pulmonar/fisiologia , Volume de Ventilação Pulmonar/fisiologia , Animais , Gasometria/veterinária , Feminino , Histerectomia/veterinária , Isoflurano/administração & dosagem , Ovariectomia/veterinária , Respiração com Pressão Positiva/veterinária , Estudos ProspectivosRESUMO
OBJECTIVE: To evaluate equine cardiopulmonary function and recovery quality after administration of 0.25 or 0.50 mg/kg xylazine intravenously (IV) during recovery. STUDY DESIGN: Randomized, blinded, prospective, clinical study. ANIMALS: Horses (n = 20). METHODS: During recovery after 3 hours of isoflurane anesthesia for arthroscopic surgery, horses were administered either 0.25 mg/kg (G25, n = 10) or 0.50 mg/kg (G50, n = 10) xylazine intravenously. Vital signs and arterial blood samples were obtained during recovery before sedation (baseline), 5, 10, 20, 30, and 45 minutes after xylazine and 30 minutes after standing. The quality of recovery scores ranged from 10 to 72 (10 = best, 72 = worst). RESULTS: G25 horses recovered faster (mean ± SD, 33 ± 5 min) than G50 horses (50 ± 7 min, P < .0001). Mean maximal decrease in arterial oxygen tension was 55 ± 11 mmHg in G25 (at 10 minutes; P < .05) and 54 ± 7 mmHg in G50 (at 20 minutes; P < .01). G25 group had a total recovery score (23 [range 18-29]) and number of attempts to stand (4 ± 2) greater than the G50 group (18 [10-23] and 1 ± 1, respectively; P < .001). CONCLUSIONS: Both doses of xylazine promoted a moderate and transient hypoxemia during recovery; however, the 0.5 mg/kg dose produced a longer and improved quality of recovery from anesthesia.
Assuntos
Período de Recuperação da Anestesia , Anestesia por Inalação/veterinária , Frequência Cardíaca/efeitos dos fármacos , Isoflurano/farmacologia , Dor Pós-Operatória/veterinária , Xilazina/farmacologia , Analgésicos/farmacologia , Anestésicos Inalatórios/farmacologia , Animais , Artroscopia/efeitos adversos , Artroscopia/veterinária , Bicarbonatos/sangue , Análise Química do Sangue/veterinária , Glicemia , Temperatura Corporal , Dióxido de Carbono/sangue , Cavalos , Concentração de Íons de Hidrogênio , Oxigênio/sangue , Dor Pós-Operatória/prevenção & controleRESUMO
OBJECTIVE: To assess if positive end-expiratory pressure (PEEP) titration improves gas exchange and respiratory mechanics, without hemodynamic impairment in horses during anesthesia. DESIGN: Prospective, randomized study. ANIMALS: Thirteen isoflurane-anesthetized healthy horses. METHODS: After 60 minutes of anesthesia with spontaneous breathing, mechanical ventilation was initiated with an inspiratory-expiratory ratio of 1:2, PEEP of 5 cmH2O, tidal volume of 10-20 mL kg(-1) and respiratory rate adjusted to maintain normocapnia. Constant PEEP of 5 cmH2O was continued (control group; n = 6) or titrated (PEEP group; n = 7) by increasing and decreasing PEEP from 5 to 20 cmH2O at 15-minute intervals. The horses were instrumented with an arterial catheter to measure blood pressure and allow collection of blood for pH and blood gas analysis and a Swan-Ganz catheter for measurement of cardiac output (CO) using thermodilution. Cardiopulmonary assessment was recorded before PEEP titration and after 15 minutes at each PEEP value. RESULTS: In the PEEP group, static compliance (range) (Cst 278-463 mL cmH2O(-1)) was significantly higher and the shunt fraction (Q·s/Q·t 7-20%) and the alveolar-arterial oxygen difference [P(A-a)O2 95-325 mmHg] were significantly lower than in the control group [Cst of 246-290 mL cmH2O(-1), Q·s/Q·t of 16-19%, P(A-a)O2 of 253-310 mmHg; p < 0.05]. CO (mean ± SEM) was lower in the PEEP group (23 ± 2 L minute(-1)) at 20 cmH2O PEEP than in the control group (26 ± 4 L minute(-1), p < 0.05), with no significant changes in heart rate, blood pressure or central venous pressure. CONCLUSIONS: PEEP titration significantly improved gas exchange and lung compliance, with a small decrease in CO at the highest PEEP level. CLINICAL RELEVANCE: Gas exchange and respiratory mechanics impairment during inhalation anesthesia can be treated using PEEP titration from 5 to 20 cmH2O, without clinically important hemodynamic effects in healthy horses.
Assuntos
Anestesia Geral/veterinária , Cavalos/cirurgia , Respiração com Pressão Positiva/veterinária , Troca Gasosa Pulmonar/fisiologia , Mecânica Respiratória/fisiologia , Anestesia Geral/métodos , Animais , Gasometria/veterinária , Pressão Sanguínea/fisiologia , Débito Cardíaco/fisiologia , Hemodinâmica , Cavalos/fisiologia , Respiração com Pressão Positiva/métodos , Taxa Respiratória/fisiologiaRESUMO
OBJECTIVE: To assess the cardiopulmonary effects of ephedrine and phenylephrine for management of isoflurane-induced hypotension in horses. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Fourteen isoflurane-anesthetized horses undergoing digital palmar neurectomy. METHODS: Ephedrine (EPH group; 0.02 mg kg(-1) minute(-1); n = 7) or phenylephrine (PHE group; 0.002 mg kg(-1) minute(-1); n = 7) was administered to all horses when mean arterial pressure (MAP) was <60 mmHg. The infusions were ended when the target MAP was achieved, corresponding to a 50% increase over the pre-infusion MAP (baseline). The horses were instrumented with an arterial catheter to measure blood pressure and allow the collection of blood for pH and blood-gas analysis and a Swan-Ganz catheter for measurement of cardiac output using thermodilution. Cardiopulmonary parameters were recorded at baseline and at 5, 30, 60 and 90 minutes after achieving the target MAP. RESULTS: In both groups, the MAP and systemic vascular resistance (SVR) increased significantly at 5, 30, 60 and 90 minutes post infusion compared to baseline (p < 0.05). The EPH group had a significant increase in cardiac index (CI) and systemic oxygen delivery index at 5, 30, 60 and 90 minutes post infusion compared to baseline (p < 0.05) and compared to the PHE group (p < 0.05). The PHE group had significantly higher SVR and no decrease in oxygen extraction compared with the EPH group at 30, 60 and 90 minutes post infusion (p < 0.05). No significant differences in ventilatory parameters were observed between groups after the infusion. CONCLUSIONS: Ephedrine increased the MAP by increasing CI and SVR. Phenylephrine increased MAP by increasing SVR but cardiac index decreased. Ephedrine resulted in better tissue oxygenation than phenylephrine. CLINICAL RELEVANCE: Ephedrine would be preferable to phenylephrine to treat isoflurane-induced hypotension in horses since it increases blood flow and pressure.
Assuntos
Pressão Sanguínea/efeitos dos fármacos , Efedrina/farmacologia , Cavalos , Hipotensão/veterinária , Fenilefrina/farmacologia , Simpatomiméticos/farmacologia , Anestésicos Gerais/efeitos adversos , Animais , Hipotensão/induzido quimicamente , Hipotensão/tratamento farmacológicoRESUMO
OBJECTIVE: To determine if pressure support ventilation (PSV) weaning from general anesthesia affects ventilation or oxygenation in horses. STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Twenty client-owned healthy horses aged 5 ± 2 years, weighing 456 ± 90 kg. METHODS: In the control group (CG; n = 10) weaning was performed by a gradual decrease in respiratory rate (fR ) and in the PSV group (PSVG; n = 10) by a gradual decrease in fR with PSV. The effect of weaning was considered suboptimal if PaCO2 > 50 mmHg, arterial pH < 7.35 plus PaCO2 > 50 mmHg or PaO2 < 60 mmHg were observed at any time after disconnection from the ventilator until 30 minutes after the horse stood. Threshold values for each index were established and the predictive power of these values was tested. RESULTS: Pressure support ventilation group (PSVG) had (mean ± SD) pH 7.36 ± 0.02 and PaCO2 41 ± 3 mmHg at weaning and the average lowest PaO2 69 ± 6 mmHg was observed 15 minutes post weaning. The CG had pH 7.32 ± 0.02 and PaCO2 57 ± 6 mmHg at weaning and the average lowest PaO2 48 ± 5 mmHg at 15 minutes post weaning. No accuracy in predicting weaning effect was observed for fR (p = 0.3474), minute volume (p = 0.1153), SaO2 (p = 0.1737) and PaO2 /PAO2 (p = 0.1529). A high accuracy in predicting an optimal effect of weaning was observed for VT > 10 L (p = 0.0001), fR /VT ratio ≤ 0.60 breaths minute(-1) L(-1) (p = 0.0001), VT /bodyweight > 18.5 mL kg(-1) (p = 0.0001) and PaO2 /FiO2 > 298 (p = 0.0002) at weaning. A high accuracy in predicting a suboptimal effect of weaning was observed for VT < 10 L (p = 0.0001), fR /VT ratio ≥ 0.60 breaths minute(-1) L(-1) (p = 0.0001) and Pe'CO2 ≥ 38 mmHg (p = 0.0001) at weaning. CONCLUSIONS AND CLINICAL RELEVANCE: Pressure support ventilation (PSV) weaning had a better respiratory outcome. A higher VT , VT /body weight, PaO2 /FiO2 ratio and a lower fR /VT ratio and Pe'CO2 were accurate in predicting the effect of weaning in healthy horses recovering from general anesthesia.
Assuntos
Período de Recuperação da Anestesia , Anestesia Geral/veterinária , Cavalos/fisiologia , Oxigênio/sangue , Respiração Artificial/veterinária , Animais , Respiração , Respiração Artificial/métodosRESUMO
OBJECTIVE: To test the effectiveness and safety of tramadol plus metamizole combined or not with a non-steroidal anti-inflammatory drug (NSAID) for treating moderate to severe chronic neoplastic pain in dogs, and its impact on quality of life (QL). STUDY DESIGN: Prospective, uncontrolled, open-label, clinical study. ANIMALS: Sixty nine client-owned dogs with multiple forms of cancer and visual analog scale (VAS) pain score ≥ 40 after receiving NSAIDs for at least 7 days. METHODS: The MN group received metamizole + NSAID, MNT group received metamizole + NSAID + tramadol and MT group received metamizole + tramadol. Pain was scored by the 0 to 100 mm VAS (0 = no pain, 100 = worst pain) and analgesic therapy was considered effective if 25 mm differences in VAS scores were observed between day 0 and the follow ups. The QL was evaluated according to a 0 to 36 scoring method for dogs (0 = worst, 36 = best) and side effects were recorded. Data were registered at day 0 (baseline) and at the first and second follow ups (7 and 14 days after day 0, respectively). RESULTS: The MN group had less analgesia at day 7 (25%) and day 14 (42%) than MNT (59%, p = 0.0274; 76%, p = 0.0251, respectively) and MT groups (69%, p = 0.0151; 81%, p = 0.0341, respectively). The QL scores were lower in the MN group at the first (score 23) and second follow up (score 26) than in MNT (27, p = 0.0847; 30, p = 0.0002) and MT (28, p = 0.0384; 31, p = 0.0001) groups. Side effects were more commonly observed in the MN group (87%) than in MNT (24%, p < 0.0001) and MT groups (25%, p = 0.0003) at the first follow up. CONCLUSIONS AND CLINICAL RELEVANCE: Tramadol plus metamizole combined or not with NSAID were well tolerated and clinically effective to treat moderate to severe pain in dogs with cancer and improved QL.