Propofol Versus 4-hydroxybutyric Acid in Pediatric Cardiac Catheterizations

Cardiorespiratory effects of gamma-hydroxybutyric acid during isoflurane anaesthesia in pigs

OBJECTIVE

To investigate the haemodynamic effects of gamma-hydroxybutyric acid (GHB) in isoflurane-anaesthetized pigs.

STUDY DESIGN

Experimental, randomized, nonblinded, crossover study.

ANIMALS

A group of six stress-resistant Landrace pigs (approximately 3 months old; three male, three female; bodyweight 39.2 ± 4 kg, mean ± standard deviation).

METHODS

After premedication (midazolam 0.5 mg kg-1 and ketamine 10 mg kg-1 intramuscularly) and induction [propofol 0.25-0.5 mg kg-1 intravenously (IV)], anaesthesia was maintained with isoflurane in oxygen, and either GHB 250 mg kg-1 IV or an equal volume of saline was administered (minimum washout period 1 week). Systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures, heart rate and rhythm and respiratory rate were recorded every 5 minutes for 2 hours. Arterial samples were collected for blood gas and pharmacokinetic analyses. Relative changes from baseline were calculated and compared between treatments using a mixed model with time, period and treatment as variables (α < 0.05).

RESULTS

Changes from baseline differed significantly between treatments (p < 0.001) for SAP (GHB -1.6 ± 10.7; saline -5.9 ± 14.8 mmHg), DAP (GHB +2.9 ± 9.6; saline -6.5 ± 10.7 mmHg) and MAP (GHB +2.2 ± 10.5; saline -5.7 ± 9.6 mmHg). Statistical analysis of secondary outcomes suggested effects on PaO2 [GHB -45.2 ± 29.8 mmHg (-6.03 ± 3.97 kPa); saline +24.5 ± 32.4 mmHg (+3.27 ± 4.32 kPa); p < 0.001] and PaCO2 [GHB -2 ± 10 mmHg (-0.27 ± 1.33 kPa); saline -9 ± 8 mmHg (-1.20 ± 1.07 kPa); p < 0.001]. Mean maximum blood concentration of GHB was 1171.1 ± 229.3 μg mL-1, with volume of distribution 335.3 ± 68.5 mL kg-1, clearance 77.2 ± 19.12 mL kg-1 hour-1 and elimination half-life 3.10 ± 0.80 hours.

CONCLUSIONS AND CLINICAL RELEVANCE

GHB did not cause severe physiological side effects and may reduce cardiovascular depression.

Dose titration of intravenously administered gamma-hydroxybutyric acid for sedation in Holstein-Friesian calves

Gamma-hydroxybutyric acid (GHB) is a short-chain fatty acid that can potentially provide safe, prolonged sedation with minimal cardiorespiratory effects. This preliminary trial, performed in 10 three-week-old male Holstein-Friesian calves, investigated the effects of GHB administered intravenously over 5 min at a dose of 100 (G100, n=2), 150 (G150, n=4) or 200 mg/kg (G200, n=4). Once lateral recumbency was achieved, scores for sedation depth (range: 0 = no sedation to 3 = marked) and response to noxious stimulation (range: 0 = strong to 3 = absent), heart rate (HR), respiratory rate (RR), mean arterial pressure (MAP) and arterial blood gases were monitored every 15 min until sternal recumbency. Times from end of administration to lateral recumbency and return to sternal/standing positions were recorded. Dose G100 resulted in mild sedation and ataxia without decubitus. Doses G150 and G200 respectively resulted in time to lateral recumbency 8 ± 2 and 9 ± 3 min, lasting 189 ± 41 and 283 ± 29 min, while overall median (range) scores for sedation were 3 (1-3) and 3 (2-3) respectively and response to noxious stimulation 0 (0-3) and 0 (0-3) respectively. The mean ± SD for HR was 110 ± 10 and 106 ± 11 bpm respectively; for MAP 87±9 and 94±5 mmHg respectively; and for RR 28 ± 5 and 26 ± 5 bpm respectively. The mean ± SD for arterial partial pressure of oxygen (PaO2) at these two dose rates was 74 ± 6 and 74 ± 2 mmHg respectively, while the arterial partial pressure of carbon dioxide oxygen (PaCO2) was 53 ± 3 and 47 ± 0.8 mmHg respectively. Based on these preliminary results we conclude that GHB has the potential to be used as a long-acting sedative in calves. Further studies are needed to confirm this.