Volatile anaesthetics and positive pressure ventilation reduce left atrial performance: a transthoracic echocardiographic study in young healthy adults

Background Animal and in vitro studies suggest that volatile anaesthetics affect left atrial (LA) performance. We hypothesized that human LA pump function and dimensions are altered by volatile anaesthetics in vivo. Methods We performed transthoracic echocardiographic (TTE) measurements in 59 healthy subjects (aged 18-48 yr) undergoing minor surgery under general anaesthesia. The unpremedicated patients were randomly assigned to anaesthesia with sevoflurane, desflurane, or isoflurane. TTE examinations were performed at baseline and after induction of anaesthesia and upon placement of a laryngeal mask during spontaneous breathing. After changing to intermittent positive pressure ventilation (IPPV), an additional TTE was performed. The study focused on the velocity-time integral of late peak transmitral inflow velocity (AVTI) and maximum LA volume. Results We found no evidence for relevant differences in the effects of the three volatile anaesthetics. AVTI decreased significantly from 4.1 (1.2) cm at baseline to 3.2 (1.1) cm during spontaneous breathing of 1 minimum alveolar concentration of volatile anaesthetics. AVTI decreased further to 2.8 (1.0) cm after changing to IPPV. The maximum LA volume was 45.4 (18.6) cm3 at baseline and remained unchanged during spontaneous breathing but decreased to 34.5 (16.7) cm3 during IPPV. Other parameters of LA pump function and dimensions decreased similarly. Conclusions Volatile anaesthetics reduced active LA pump function in humans in vivo. Addition of IPPV decreased LA dimensions and further reduced LA pump function. Effects in vivo were less pronounced than previously found in in vitro and animal studies. Further studies are warranted to evaluate the clinical implications of these findings. Clinical trial registration NCT002445

Performance of a new pulse contour method for continuous cardiac output monitoring: validation in critically ill patients

Background A new calibrated pulse wave analysis method (VolumeView™/EV1000™, Edwards Lifesciences, Irvine, CA, USA) has been developed to continuously monitor cardiac output (CO). The aim of this study was to compare the performance of the VolumeView method, and of the PiCCO2™ pulse contour method (Pulsion Medical Systems, Munich, Germany), with reference transpulmonary thermodilution (TPTD) CO measurements. Methods This was a prospective, multicentre observational study performed in the surgical and interdisciplinary intensive care units of four tertiary hospitals. Seventy-two critically ill patients were monitored with a central venous catheter, and a thermistor-tipped femoral arterial VolumeView™ catheter connected to the EV1000™ monitor. After initial calibration by TPTD CO was continuously assessed using the VolumeView-CCO software (CCOVolumeView) during a 72 h period. TPTD was performed in order to obtain reference CO values (COREF). TPTD and arterial wave signals were transmitted to a PiCCO2™ monitor in order to obtain CCOPiCCO values. CCOVolumeView and CCOPiCCO were recorded over a 5 min interval before assessment of COTPTD. Bland-Altman analysis, %errors, and concordance (trend analysis) were calculated. Results A total of 338 matched sets of data were available for comparison. Bias for CCOVolumeView−COREF was −0.07 litre min−1 and for CCOPiCCO-COREF +0.03 litre min−1. Corresponding limits of agreement were 2.00 and 2.48 litre min−1 (P<0.01), %errors 29 and 37%, respectively. Trending capabilities were comparable for both techniques. Conclusions The performance of the new VolumeView™-CCO method is as reliable as the PiCCO2™-CCO pulse wave analysis in critically ill patients. However, an improved precision was observed with the VolumeView™ technique. Clinicaltrials.gov identifier NCT0140504

Influence of steep Trendelenburg position and CO2 pneumoperitoneum on cardiovascular, cerebrovascular, and respiratory homeostasis during robotic prostatectomy

The steep (40 degrees) Trendelenburg position optimizes surgical exposure during robotic prostatectomy. The goal of the current study was to investigate the combined effect of this position and CO2 pneumoperitoneum on cardiovascular, cerebrovascular, and respiratory homeostasis during these procedures. Physiological data were recorded during the whole surgical procedure in 31 consecutive patients who underwent robotic endoscopic radical prostatectomy under general anaesthesia. Heart rate, mean arterial pressure, central venous pressure, Sp(o2), Pe'(co2), P-Plat, tidal volume, compliance, and minute ventilation were monitored and recorded. Arterial samples were obtained to determine the arterial-to-end-tidal CO2 tension gradient. Continuous regional cerebral tissue oxygen saturation (Sct(o2)) was determined by near-infrared spectroscopy. Although patients were in the Trendelenburg position, all variables investigated remained within a clinically acceptable range. Cerebral perfusion pressure (CPP) decreased from 77 mm Hg at baseline to 71 mm Hg (P=0.07), and Sct(o2) increased from 70% to 73% (P < 0.001). Pe'(co2) increased from 4.12 to 4.79 kPa (P < 0.001) and the arterial-to-Pe'(co2) tension difference increased from 1.06 kPa in the normal position to a maximum of 1.41 kPa (P < 0.001) after 2 h in the Trendelenburg position. The combination of the prolonged steep Trendelenburg position and CO2 pneumoperitoneum was well tolerated. Haemodynamic and pulmonary variables remained within safe limits. Regional cerebral oxygenation was well preserved and CPP remained within the limits between which cerebral blood flow is usually considered to be maintained by cerebral autoregulation

Comparative Study of Carp Pituitary Extracts (CPE) and Ovupin-L on Induced Breeding in African Catfish (Clarias gariepinus)

A comparative study of Carp Pituitary Extract (CPE) and Ovupin-L on induced breeding of African catfish (Clarias gariepinus) was conducted in applied hydrobiology and fisheries unit of Zoology Department, University of Jos. 24 brood stocks (12 males and 12 females) were sourced and selected from a private fish farm at Gangare, behind Murtala house Jos between the months of July to August 2010. Four of the females were hypophysized with 3mg, 4mg, 5mg and 6mg/kg body weight (BW) respectively of carp pituitary extract; four were hypophysized with 0.3, 0.4, 0.5, and 0.6mg/kg (BW) ovupin-L while the remaining four were injected with 0.3, 0.4, 0.5, and 0.6ml/kg (BW) of normal saline which serve as a control. The females were isolated separately and kept in plastic tanks (A-L) for latency period of 14hrs after hypophysation, while the males were kept in a single plastic tank. And were later dissected and testis removed to obtain milt which was used to fertilize the stripped eggs. The number of eggs spawned was estimated using standard formula. The result revealed that, all the females hypophysized with CPE and ovupin-L spawned in all the dosages but no fish spawned in all the dosages of normal saline. Ovupin-L at 0.5 ml/kg gave the best result in all the four parameters of fecundity investigated. There was a significant difference between the CPE and ovupin-L on fecundity and fertilization of Clarias gariepinus with ovupin-L performing better than CPE in all the parameters (p &lt;0.05). Ovupin-L at dosage of 0.5ml/kg highly significant than other tested parameters in Clarias gariepinus, the dosage with the lowest output was obtained with CPE at 0.4mg/kg body weight. Keywords: carp pituitary, extract, ovupin-L, African catfish, induced breeding, hypophysation

Changes in resting neural connectivity during propofol sedation.

BACKGROUND: The default mode network consists of a set of functionally connected brain regions (posterior cingulate, medial prefrontal cortex and bilateral parietal cortex) maximally active in functional imaging studies under "no task" conditions. It has been argued that the posterior cingulate is important in consciousness/awareness, but previous investigations of resting interactions between the posterior cingulate cortex and other brain regions during sedation and anesthesia have produced inconsistent results. METHODOLOGY/PRINCIPAL FINDINGS: We examined the connectivity of the posterior cingulate at different levels of consciousness. "No task" fMRI (BOLD) data were collected from healthy volunteers while awake and at low and moderate levels of sedation, induced by the anesthetic agent propofol. Our data show that connectivity of the posterior cingulate changes during sedation to include areas that are not traditionally considered to be part of the default mode network, such as the motor/somatosensory cortices, the anterior thalamic nuclei, and the reticular activating system. CONCLUSIONS/SIGNIFICANCE: This neuroanatomical signature resembles that of non-REM sleep, and may be evidence for a system that reduces its discriminable states and switches into more stereotypic patterns of firing under sedation

Impact of propofol on mid-latency auditory-evoked potentials in children†

Background Propofol is increasingly used in paediatric anaesthesia, but can be challenging to titrate accurately in this group. Mid-latency auditory-evoked potentials (MLAEPs) can be used to help titrate propofol. However, the effects of propofol on MLAEP in children are unclear. Therefore, we investigated the relationship between propofol and MLAEP in children undergoing anaesthesia. Methods Fourteen healthy children aged 4-16 yr received anaesthesia for elective surgery. Before surgery, propofol was administered in three concentrations (3, 6, 9 µg ml−1) through a target-controlled infusion pump using Kataria and colleagues' model. MLAEPs were recorded 5 min after having reached each target propofol concentration at each respective concentration. Additionally, venous propofol blood concentrations were assayed at each measuring time point. Results Propofol increased all four MLAEP peak latencies (peaks Na, Pa, Nb, P1) in a dose-dependent manner. In addition, the differences in amplitudes were significantly smaller with increasing propofol target concentrations. The measured propofol plasma concentrations correlated positively with the latencies of the peaks Na, Pa, and Nb. Conclusions Propofol affects MLAEP latencies and amplitudes in children in a dose-dependent manner. MLAEP measurement might therefore be a useful tool for monitoring depth of propofol anaesthesia in childre

Hypotension during propofol sedation for colonoscopy – an exploratory analysis

Background. Intraoperative and post-operative hypotension occur commonly and are associated with organ injury and poor outcomes. Changes in blood pressure during procedural sedation are not well described. Methods. Individual patient data from five trials of propofol sedation for colonoscopy and a clinical database were pooled and explored with logistic and linear regression. A literature search and focussed meta-analysis compared the incidence of hypotension with propofol and alternative forms of procedural sedation. Hypotensive episodes were characterised by the original authors’ definitions, typically systolic blood pressure 5 minutes and in 89 (23%) the episodes exceeded 10 minutes. Meta-analysis of eighteen Randomised Controlled Trials identified an increased Risk Ratio for the development of hypotension in procedures where propofol was used compared to the use of etomidate (2 studies, n=260, RR 2.0 [95% CI 1.37 – 2.92], p=0.0003), remimazolam (1 study, n=384, RR 2.15 [1.61 – 2.87], p=0.0001), midazolam (14 studies, n=2218, RR 1.46 [ 1.18 – 1.79], p=0.0004) or all benzodiazepines (15 studies, n=2602, 1.67 [1.41 – 1.98], p<0.00001). Hypotension was less likely with propofol than when dexmedetomidine was used (1 study, n=60, RR 0.24 [0.09 – 0.62], p=0.003). Conclusions. Hypotension is common during propofol sedation for colonoscopy and of a magnitude and duration associated with harm in surgical patients