Evaluation of sevoflurane and isoflurane as maintenance agent in buffaloes after glycopyrrolate-xylazine-butorphanol-propofol anaesthesia

The study was aimed to compare the efficacy and safety of isoflurane and sevoflurane as maintenance agent in a balanced anaesthetic combination for buffaloes undergoing diaphragmatic herniorrhaphy. Twelve clinical cases of diaphragmatic hernia in female buffaloes were randomly selected and assigned to two groups (PS and PI) of six animals each. After premedication with glycopyrrolate, xylazine and butorphanol, induction was done with propofol. For maintenance, either sevoflurane (PS) or isoflurane (PI) was used with oxygen through a partial rebreathing system. Clinical, physiological, behavioral, haematological and biochemical parameters were recorded at different intervals. No significant differences were observed in maintenance scores, degree of muscle relaxation as well as haematological and blood biochemical parameters between the groups. The heart and respiratory rates were observed to be less depressed in PS than in PI. The recovery and standing with ataxia in PS was significantly earlier than the PI. Both isoflurane and sevoflurane were found to be safe and effective maintenance anaesthetic agents for buffaloes undergoing diaphragmatic herniorrhaphy; however, the sevoflurane was assessed to be slightly better as maintenance agent because of faster recovery and lesser cardiovascular depression than isoflurane.

Treatment of acute migraine by a partial rebreathing device: A randomized controlled pilot study

Background Impaired brain oxygen delivery can trigger and exacerbate migraine attacks. Normoxic hypercapnia increases brain oxygen delivery markedly by vasodilation of the cerebral vasculature, and hypercapnia has been shown to abort migraine attacks. Stable normoxic hypercapnia can be induced by a compact partial rebreathing device. This pilot study aimed to provide initial data on the device’s efficacy and safety. Methods Using a double-blinded, randomized, cross-over study design, adult migraine-with-aura patients self-administered the partial rebreathing device or a sham device for 20 minutes at the onset of aura symptoms. Results Eleven participants (mean age 35.5, three men) self-treated 41 migraine attacks (20 with the partial rebreathing device, 21 with sham). The partial rebreathing device increased mean End Tidal CO2 by 24%, while retaining mean oxygen saturation above 97%. The primary end point (headache intensity difference between first aura symptoms and two hours after treatment (0–3 scale) – active/sham difference) did not reach statistical significance (−0.55 (95% CI: −1.13–0.04), p = 0.096), whereas the difference in percentage of attacks with pain relief at two hours was significant ( p = 0.043), as was user satisfaction ( p = 0.022). A marked efficacy increase was seen from first to second time use of the partial rebreathing device. No adverse events occurred, and side effects were absent or mild. Conclusion Normoxic hypercapnia shows promise as an adjunctive/alternative migraine treatment, meriting further investigation in a larger population. Clinical study registered at ClinicalTrials.gov with identifier NCT03472417

Sources of Error in Noninvasive Pulmonary Blood Flow Measurements by Partial Rebreathing

Background Partial rebreathing is a noninvasive method for measuring pulmonary blood flow (PBF). This study examines the systematic errors produced by the partial rebreathing technique utilizing a comprehensive mathematical model of the cardiorespiratory system of a healthy, 70-kg adult male. Methods The model simulates tidal breathing through a branched respiratory tree and incorporates the effects on carbon dioxide dynamics of lung tissue mass, vascular transport delays, multiple body compartments, and realistic blood-gas dissociation curves. Four studies were performed: (1) errors produced under standard conditions, (2) effects of recirculation, (3) effects of alveolar-proximal airway partial pressure of carbon dioxide (Pco(2)) differences, and (4) effects of rebreathing time. Results Systematic errors are less than 10% when the simulated PBF is between 3 and 6 l/min. At 2 l/min, PBF is overestimated by approximately 35%. At 14 l/min, PBF is underestimated by approximately 40%. At PBF of greater than 6 l/min, recirculation causes approximately 60% of the systematic error, alveolar-proximal airway differences cause approximately 20%, and alveolar-arterial differences cause approximately 20%. The standard rebreathing time of 50 s is shown to be excessive for PBF of greater than 6 l/min. At PBF of less than 3 l/min, errors are caused by inadequate rebreathing time and alveolar-arterial gradients. Conclusions Systematic errors in partial rebreathing cardiac output measurements have multiple causes. Our simulations suggest that errors can be reduced by using a variable rebreathing time, which should be increased at low PBF so that quasi-equilibrium in the alveoli can be achieved and decreased at high PBF to reduce the effects of recirculation.