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Objective: To compare the variability in the duration of action of a single dose of rocuronium or cisatracurium, and duration of subsequent top‐up doses in anesthetized dogs. Animals: Thirty dogs requiring ophthalmic surgery with neuromuscular block. Procedures: Neuromuscular function was monitored with train‐of‐four (TOF) and acceleromyography. Dogs received an initial dose of rocuronium 0.6 mg/kg, or cisatracurium 0.15 mg/kg IV, which produced complete neuromuscular block. Upon return of the first response (T1) of TOF, a third of the initial dose was repeated. The duration of the initial dose and its variability were compared between agents. Duration of subsequent top‐up doses was assessed with mixed effect models. Spontaneous (from last return of T1) or neostigmine‐enhanced (from administration to complete recovery) recovery times were measured for each agent. Results: Duration of action of the initial dose was [median (range)] 25 (10–60) min with rocuronium and 35 (15–45) min with cisatracurium (p =.231). The variability of rocuronium was 3.25 times larger than cisatracurium (p =.034). Duration of top‐up doses did not vary for either agent. Spontaneous recovery was shorter for rocuronium [15 (10–20) min] than cisatracurium [25 (15–45) min] (p =.02). Neostigmine‐enhanced recovery times were 5 (5–25) for rocuronium and 10 (5–10) for cisatracurium (p =.491). Conclusions: Duration of action for a single dose is significantly more variable with rocuronium than cisatracurium. Time to spontaneous recovery was longer for cisatracurium, and cases of unexpectedly long recovery times were observed with both agents. Objective monitoring is recommended. [ABSTRACT FROM AUTHOR]

Background Dynamic indicators such as pulse pressure and stroke volume variations can be measured to track changes in preload during hemorrhage, and evaluate fluid therapy. However, these dynamic indicators require mechanical ventilation, and might be affected by cardiac dysrhythmias and changes in vascular tone. Blood volume indicators may offer alternatives for assessing changes in volume status. Aims The aims of this study were to measure changes in blood volume indicators and dynamic indicators during removal of blood in two stages and subsequent blood replacement in anesthetized, mechanically ventilated, neonatal pigs. Methods In eight anesthetized, mechanically ventilated piglets (5-6 weeks old), cardiac index, stroke volume index, total end-diastolic volume, central blood volume, active circulating volume, pulse pressure variation, and stroke volume variation were measured during blood removal in two stages (15 mL kg−1 each stage) and blood replacement (30 mL kg−1). Values after each intervention were measured for each parameter. Results All indicators differed from baseline after removal of 15 mL kg−1 of blood, except for stroke volume variation. Differences between both stages of hemorrhage were only observed for indexed stroke volume, total end-diastolic volume, central blood volume, and pulse pressure variation. Conclusion Total end-diastolic volume and central blood volume changed during blood depletion and repletion, and differed between stages of hemorrhage. These indicators might be useful for assessing volume status instead of, or in addition to cardiac index and dynamic indicators. [ABSTRACT FROM AUTHOR]

Background The COstatus monitor measures cardiac output via the transpulmonary ultrasound dilution method ( COTPUD) after injection of normal saline, and can calculate continuous cardiac output ( CCO) from the arterial pressure waveform. The relationship between arterial waveform and COTPUD however, might be degraded during vasoconstriction/vasodilation. Objectives To examine if recalibration of arterial waveform-derived CCO is required during mild vasoconstriction/vasodilation. Methods In 10 anesthetized piglets (6.6-10.1 kg), two COstatus monitors calculated the CCO from the same femoral arterial waveform before and during infusions of phenylephrine ( PE; 1 or 3 mg·kg−1·min−1) and sodium nitroprusside ( SNP; 1 or 5 mg·kg−1·min−1), administered in random order. One monitor was recalibrated (CCO Recal) after each intervention, while the other monitor was not (CCO Non-Recal). Recalibration was performed with COTPUD with 1 ml·kg−1 normal saline as indicator. The effects of each infusion on hemodynamic parameters were compared with baseline using paired t-tests. The bias, limits of agreement ( LOA), and percentage error between simultaneous measurements (CCO Recal and CCO Non-Recal) were examined with Bland-Altman plots. Results Infusion of PE significantly increased COTPUD, heart rate ( HR), and arterial pressures but not systemic vascular resistance ( SVR). Infusion of SNP decreased arterial pressures without affecting COTPUD, HR, and SVR. There was no bias between CCO Recal and CCO Non-Recal at the baseline, but a small bias was observed during PE and SNP infusions. The LOA increased approximately 10 fold during vasoconstriction and vasodilation. The percentage error increased from ≤ 5% to 32% and 27% during PE and SNP infusions, respectively. Conclusion Continuous cardiac output ( CO) measured with the COstatus monitor requires recalibration during vasoconstriction and vasodilation, even if changes in COTPUD or SVR are not substantial. [ABSTRACT FROM AUTHOR]

Objective– To determine if horses before undergoing anesthesia for surgical correction of colic would have lower plasma arginine vasopressin (AVP) concentrations than healthy horses undergoing anesthesia for arthroscopic surgery, and would not increase their plasma AVP concentrations in response to anesthesia and surgery. Design– Prospective clinical study. Setting– University teaching hospital. Animals– Fourteen horses with colic and 8 healthy horses. Interventions– Horses with colic underwent anesthesia and surgery for alleviation of colic, and healthy horses underwent anesthesia and surgery for arthroscopy. Measurements and Main Results– Plasma AVP was measured perioperatively in horses with colic and in healthy horses. Before anesthesia, and 30 and 60 minutes after induction, horses with colic had greater median plasma AVP concentrations than control horses ( P≤0.001); thereafter during anesthesia differences in AVP concentrations between the 2 groups were not significant. In the control group, plasma AVP concentration increased during 120 minutes of anesthesia; no such increase occurred in colic horses. Conclusions– Compared with healthy horses, horses with colic had higher preanesthesia plasma AVP concentrations that did not increase further in response to anesthesia and surgery. Exogenous AVP is associated with decreased splanchnic perfusion in a variety of animal species and, therefore, could be detrimental to horses with colic. Thus, it may be inappropriate to use exogenous AVP in support of blood pressure in anesthetized horses with colic. Further studies are warranted to define appropriate indications for the use of AVP in horses with colic. [ABSTRACT FROM AUTHOR]

To determine conversion formulas so that values from the HemoCue® hemoglobinometer (HbHQ) could be equated to hemoglobin concentrations measured by the gold-standard cyanomethemoglobin (HbCY) method and used for estimation of packed cell volume (PCV) in cats.Prospective,in vitro.Twelve healthy, adult, client-owned cats.The PCV of 12 parent blood samples was manipulated between∼3 and∼80% by removing or adding autologous plasma. Hemoglobin was measured by the HbCY method at a university clinical pathology laboratory and by the azidemethemoglobin method in a HbHQ. PCV was determined by micro-centrifugation.Hemoglobin varied from 1–26 g/dL. Repeated-measures regression of HbCY on HbHQ demonstrated that theY-intercept was not different from zero. When the regression was repeated, forcing the line through the origin the coefficient for converting HbHQ to HbCY was not significantly different from 1.0 (adjustedR2=99.7%). The conversion formula was HbCY=HbHQ. Using similar methods, the conversion formula for estimating PCV was PCV=3.1 HbHQ (adjustedR2=99.8%).Hemoglobin concentration measured by the HemoCue® was indistinguishable from the (HbCY) method in feline blood over a wide range of hemoglobin concentrations. This study demonstrates that in cats PCV=3.1HbHQ.The HemoCue® is useful for point-of-care hemoglobinometry and for estimating PCV in cats. [ABSTRACT FROM AUTHOR]

Background: We evaluated the use of lumbosacral epidural anaesthesia (LEA) in dogs undergoing caesarean section over 10 years. Methods: Anaesthetic records were reviewed and divided into two treatment groups: LEA and control. Outcome variables identified a priori as potentially affected by LEA were compared between groups. Results are frequency or median (minimum–maximum). Results: Ninety‐five dogs received LEA and 87 did not. LEA consisted of 0.2 (0.1–0.3) ml/kg containing bupivacaine (n = 63), ropivacaine (n = 15), or lidocaine (n = 12) at concentrations ranging between 0.06% and 2%. Morphine, fentanyl, or buprenorphine were used as part of LEA. Groups were similar for demographic variables (all p > 0.06). Intravenous opioids were used more often in control than in LEA (p < 0.0005). Incidence of hypotension (MAP < 60 mm Hg) was LEA 68% and control 56% (p = 0.12). Duration of hypotension was longer in LEA (p = 0.03). Use of crystalloids and vasoactive drugs did not differ (all p > 0.1). Time from induction to operating room was 30 (8–75) min for control and 35 (18–65) min for LEA (p = 0.003). Discussion: LEA during caesarean section in dogs was associated with lower rates of opioid administration and did not exacerbate the incidence of hypotension. [ABSTRACT FROM AUTHOR]