Revisiting the roles of progesterone and allopregnanolone in the nervous system: Resurgence of the progesterone receptors

http://www.uco.es/organiza/departamentos/anatomia-y-anat-patologica/peques/master/juanmorgaz/Muir.pdf

The cardiorespiratory and anesthetic effects of clinical and supraclinical doses of alfaxalone in cats.

Fluid therapy is important for many medical conditions in veterinary patients. The assessment of patient history, chief complaint, physical exam findings, and indicated additional testing will determine the needfor fluid therapy. Fluid selection is dictated by the patient’s needs, including volume, rate, fluid composition required, and location the fluid is needed (e.g., interstitial versus intravascular). Therapy must be individualized, tailored to each patient, and constantly re-evaluated and reformulated according to changes in status. Needs may vary according to the existence of either acute or chronic conditions, patient pathology (e.g., acid-base, oncotic, electrolyte abnormalities), and comorbid conditions. All patients should be assessed for three types of fluid disturbances: changes in volume, changes in content, and/or changes in distribution. The goals of these guidelines are to assist the clinician in prioritizing goals, selecting appropriate fluids and rates of administration, and assessing patient response to therapy. These guidelines provide recommendations for fluid administration for anesthetized patients and patients with fluid disturbances. ( JA m Anim Hosp Assoc2013; 49:149–159. DOI 10.5326/JAAHA-MS-5868)

2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats*

Chapter 10 – Anesthesia and Analgesia for Laboratory Rodents

Safe and effective anesthesia of dogs and cats rely on preanesthetic patient assessment and preparation. Patients should be premedicated with drugs that provide sedation and analgesia prior to anesthetic induction with drugs that allow endotracheal intubation. Maintenance is typically with a volatile anesthetic such as isoflurane or sevoflurane delivered via an endotracheal tube. In addition, local anesthetic nerve blocks; epidural administration of opioids; and constant rate infusions of lidocaine, ketamine, and opioids are useful to enhance analgesia. Cardiovascular, respiratory, and central nervous system functions are continuously monitored so that anesthetic depth can be modified as needed. Emergency drugs and equipment, as well as an action plan for their use, should be available throughout the perianesthetic period. Additionally, intravenous access and crystalloid or colloids are administered to maintain circulating blood volume. Someone trained in the detection of recovery abnormalities should monitor patients throughout recovery. Postoperatively attention is given to body temperature, level of sedation, and appropriate analgesia.

https://www.vasinc.net/Anesthesia_Guidelines_for_Dogs_and_Cats.pdf

AAHA anesthesia guidelines for dogs and cats.

Determination of central venous pressure (CVP) is relevant to patients with right heart disease, hypovolemia, and following intravenous fluid therapy. We hypothesized that changes in CVP in dogs could be predicted by measurements of hepatic vein diameter, caudal vena cava (CVC) diameter, and hepatic venous flow velocities. Nine healthy American Foxhounds were anesthetized. Following baseline recordings, intravenous fluids were administered to increase CVP. Volume administration created treatment periods with CVP ranges of 5, 10, 15, 20, and 25 mm Hg. Flow velocities in the right medial hepatic vein were recorded using pulsed wave Doppler ultrasound. Hepatic vein, CVC, and aorta diameters were determined with B-mode ultrasound. Variables were compared across the treatment periods by ANOVA for repeated measures. Relationships between CVP, Doppler, and B-mode variables were evaluated using Spearman's rank correlations, multiple linear regression, and repeated measures linear regression. The a-, S- and v-wave velocities were augmented significantly with volume loading. The best part (semipartial) correlation coefficients predicting increasing CVP were identified with v-wave velocity (0.823), S-wave velocity (-0.800), CVC diameter (0.855), and hepatic vein diameter (0.815). Multiple linear regression indicated that CVP in this study could be predicted best by a combination of CVC and hepatic vein diameter and the v-wave velocity (r = 0.928). Ultrasound imaging identified gallbladder and pancreatic edema consistently, likely related to acute volume loading. These findings may be applicable in the assessment of volume status, dogs with right heart disease, and during serial monitoring of dogs receiving fluid or diuretic therapy.

Noninvasive estimation of central venous pressure in anesthetized dogs by measurement of hepatic venous blood flow velocity and abdominal venous diameter

Objective—To evaluate anesthetic effects of 4 drug combinations used for total intravenous anesthesia of horses undergoing surgical removal of an abdominal testis. Design—Clinical trial. Animals—32 healthy cryptorchid horses. Procedure—Horses were sedated with xylazine and butorphanol and were randomly assigned to 1 of 4 groups: induction of anesthesia with ketamine and diazepam and maintenance with bolus administration of ketamine and xylazine (KD/KX); induction and maintenance of anesthesia with bolus administration of tiletamine-zolazepam, ketamine, and detomidine (TKD); induction and maintenance of anesthesia with continuous infusion of xylazine, guaifenesin, and ketamine; and induction and maintenance of anesthesia with continuous infusion of guaifenesin and thiopental. Horses that moved 3 consecutive times in response to surgical stimulation or for which surgery time was > 60 minutes were administered an inhalant anesthetic, and data from these horses were excluded from analysis. Results—Quality of ...

Comparison of four drug combinations for total intravenous anesthesia of horses undergoing surgical removal of an abdominal testis.

The purpose of this study was to compare the effects of 0.5 fraction of inspired oxygen (FiO2) and >0.95 FiO2 on pulmonary gas exchange, shunt fraction and oxygen delivery (DO2) in dorsally recumbent horses during inhalant anesthesia. The use of 0.5 FiO2 has the potential to reduce absorption atelectasis (compared to maximal FiO2) and augment alveolar oxygen (O2) tensions (compared to ambient air) thereby improving gas exchange and DO2. Our hypothesis was that 0.5 FiO2 would reduce ventilation-perfusion mismatching and increase the fraction of pulmonary blood flow that is oxygenated, thus improving arterial oxygen content and DO2. Arterial partial pressures of O2 were significantly higher than preanesthetic levels at all times during anesthesia in the >0.95 FiO2 group. Arterial partial pressures of O2 did not change from preanesthetic levels in the 0.5 FiO2 group but were significantly lower than in the >0.95 FiO2 group from 15 to 90 min of anesthesia. Alveolar to arterial O2 tension difference was increased significantly in both groups during anesthesia compared to preanesthetic values. The alveolar to arterial O2 tension difference was significantly higher at all times in the >0.95 FiO2 group compared to the 0.5 FiO2 group. Oxygen delivery did not change from preanesthetic values in either group during anesthesia but was significantly lower than preanesthetic values 10 min after anesthesia in the 0.5 FiO2 group. Shunt fraction increased in both groups during anesthesia attaining statistical significance at varying times. Shunt fraction was significantly increased in both groups 10 min after anesthesia but was not different between groups. Alveolar dead space ventilation increased after 3 hr of anesthesia in both groups. Reducing FiO2 did not change alveolar dead space ventilation or shunt fraction in dorsally recumbent, mechanically ventilated horses during 3 hr of isoflurane anesthesia. Reducing FiO2 in dorsally recumbent isoflurane anesthetized horses does not improve oxygenation or oxygen delivery.

https://link.springer.com/content/pdf/10.1186%2F1746-6148-7-23.pdf

Effect of 50% and maximal inspired oxygen concentrations on respiratory variables in isoflurane-anesthetized horses.

SummaryReasons for performing the study
Midazolam is used to control seizures in horses and to enhance muscle relaxation, but its pharmacokinetics are unknown.

Objective
To determine the pharmacokinetics and sedative effects of midazolam in horses.

Study design
Blinded, randomised, crossover design.

Methods
Midazolam was administered i.v. at either 0.05 or 0.1 mg/kg bwt to 6 horses on 2 occasions at least 7 days apart using a crossover design. Blood samples were collected before and at predetermined times through 24 h after administration. Serum midazolam concentrations were determined by a liquid chromatography tandem-mass spectrometry method. Heart and respiratory rates and indices of sedation, ataxia, and sensitivity to stimuli were recorded before and at predetermined times after midazolam administration.

Results
Pharmacokinetic analysis was performed on samples from 5 horses in each group. Median total clearance was 10.6 ml/min/kg (range 6.1–15.2 ml/min/kg) and 10.4 ml/min/kg (range 8.4–17.6 ml/min/kg), and median volume of distribution at steady state was 2094 ml/kg (range 2076–2413 ml/kg) and 2822 ml/kg (range 2270–7064 ml/kg) after the 0.05 mg/kg and 0.1 mg/kg bwt doses, respectively. Median distribution half-life was 24 min (range 6–42 min) and 39 min (range 33.6–72 min) and median terminal half-life was 216 min (range 120–248 min) and 408 min (range 192–924 min) after the 0.05 mg/kg and 0.1 mg/kg bwt doses, respectively. Cardiorespiratory parameters and sedation scores did not change. Midazolam caused agitation, postural sway, weakness, and one horse became recumbent after the 0.1 mg/kg bwt dose.

Conclusions
Midazolam produces ataxia and postural sway of short duration after i.v. administration to horses. Sedation was not evident after midazolam administration. Drug redistribution is likely the primary mechanism for the termination of effect.

Potential relevance
Midazolam produces muscle relaxation but not sedation in adult horses.

Phillip Lerche

Papers

The cardiorespiratory and anesthetic effects of clinical and supraclinical doses of alfaxalone in cats.

Noninvasive estimation of central venous pressure in anesthetized dogs by measurement of hepatic venous blood flow velocity and abdominal venous diameter

Comparison of four drug combinations for total intravenous anesthesia of horses undergoing surgical removal of an abdominal testis.

Effect of 50% and maximal inspired oxygen concentrations on respiratory variables in isoflurane-anesthetized horses.

Pharmacokinetics of midazolam after intravenous administration to horses