Cardiovascular effects of inhalational anesthetics

Application of Propofol Target-Controlled Infusion for Optimized Hemodynamic Status in ESRD Patients Receiving Arteriovenous Access Surgery: A Randomized Controlled Trial

Background and Objectives: End-stage renal disease (ESRD) is associated with increased anesthetic risks such as cardiovascular events resulting in higher perioperative mortality rates. This study investigated the perioperative and postoperative outcomes in ESRD patients receiving propofol target-controlled infusion with brachial plexus block during arteriovenous (AV) access surgery. Materials and Methods: We recruited fifty consecutive patients scheduled to receive AV access surgery. While all patients received general anesthesia combined with ultrasound-guided brachial plexus block, the patients were randomly assigned to one of two general anesthesia maintenance groups, with 23 receiving propofol target-controlled infusion (TCI) and 24 receiving sevoflurane inhalation. We measured perioperative mean arterial pressure (MAP), heart rate, and cardiac output and recorded postoperative pain status and adverse events in both groups. Results: ESRD patients receiving propofol TCI had significantly less reduction in blood pressure than those receiving sevoflurane inhalation (p < 0.05) during AV access surgery. Perioperative cardiac output and heart rate were similar in both groups. Both groups reported relatively low postoperative pain score and a low incidence of adverse events. Conclusions: Propofol TCI with brachial plexus block can be used as an effective anesthesia regimen for ESRD patients receiving AV access surgery. It can be used with less blood pressure fluctuation than inhalational anesthesia.

Comparison of General, Epidural, and Spinal Anesthesia in Laparoscopic TEP (Total Extraperitoneal Repair) for Inguinal Hernia

PURPOSE

Laparoscopic total extraperitoneal repair (TEP) is one of the most preferred minimally invasive methods for inguinal hernia repair. In our study, we aimed to compare the advantages and disadvantages of general anesthesia (GA), spinal anesthesia (SA), and epidural anesthesia (EA) for TEP operations.

MATERIALS AND METHODS

This is a retrospective study involving 221 patients who underwent TEP surgery for inguinal hernia between January 2018 and July 2020. Patients were divided into 3 groups as GA (n=77), SA (n=70), and EA (n=74). Demographic data of the patients, duration of anesthesia and surgery, perioperative and postoperative complications, postoperative pain, anatomical delineation, hospital stay and quality of life were evaluated.

RESULTS

Anesthesia time was the longest in the EA group (23.1±2.32 min) and significantly prolonged the operation time (P<0.001). When the visual analog scale scores were compared, it was observed that the patients in the GA group felt significantly more pain (P<0.001). While the rates of hypotension and headache were higher in regional anesthesia (P<0.001 and P<0.002), there was no significant difference in urinary retention, postoperative nausea/vomiting, and shoulder pain (P=0.274, 0.262, and 0.314, respectively). SA and EA groups were found to be superior compared with the GA group in terms of patient satisfaction (P<0.001).

CONCLUSION

Regional anesthesia (SA and EA) can be safely performed in TEP surgeries, gives results similar to the anatomical delineation satisfactory and complication rates of GA, and results in less postoperative pain.

Occurrence of pulsus alternans during anaesthesia of two dogs and one cat and its treatment

The authors report the occurrence of pulsus alternans, a condition characterised by the alternance of pulses of higher and lower amplitude, in two dogs and one cat under general anaesthesia. The presence of an underlying cardiac disease was confirmed in the cat but not in either dog, which - based on history and clinical findings - had presumably normal cardiovascular function before the anaesthetic. Possible mechanisms, including negative inotropy and haemodynamic and Frank-Starling effects, as well as the role of general anaesthesia as the potential triggering factor, are discussed in this report. Ephedrine resulted in the successful treatment of pulsus alternans, as demonstrated by the return of normal pulse and synchronisation of heart and pulse rates in the cat and in one dog. In the other dog, pulse pattern and frequency returned to normal once the guidewire for central line placement was withdrawn.

Cardio-respirometry disruption in zebrafish (Danio rerio) embryos exposed to hydraulic fracturing flowback and produced water

Hydraulic fracturing to extract oil and natural gas reserves is an increasing practice in many international energy sectors. Hydraulic fracturing flowback and produced water (FPW) is a hyper saline wastewater returned to the surface from a fractured well containing chemical species present in the initial fracturing fluid, geogenic contaminants, and potentially newly synthesized chemicals formed in the fracturing well environment. However, information on FPW toxicological mechanisms of action remain largely unknown. Both cardiotoxic and respirometric responses were explored in zebrafish (Danio rerio) embryos after either an acute sediment-free (FPW-SF) or raw/sediment containing (FPW-S) fraction exposure of 24 and 48 h at 2.5% and 5% dilutions. A 48 h exposure to either FPW fraction in 24-72 h post fertilization zebrafish embryos significantly increased occurrences of pericardial edema, yolk-sac edema, and tail/spine curvature. In contrast, larval heart rates significantly decreased after FPW fraction exposures. FPW-S, but not FPW-SF, at 2.5% doses significantly reduced embryonic respiration/metabolic rates (MO₂), while for 5% FPW, both fractions reduced MO₂. Expression of select cardiac genes were also significantly altered in each FPW exposure group, implicating a cardiovascular system compromise as the potential cause for reduced embryonic MO₂. Collectively, these results support our hypothesis that organics are major contributors to cardiac and respiratory responses to FPW exposure in zebrafish embryos. Our study is the first to investigate cardiac and respiratory sub-lethal effects of FPW exposure, demonstrating that FPW effects extend beyond initial osmotic stressors and verifies the use of respirometry as a potential marker for FPW exposure.

An Evolving Uncontrolled Hemorrhage Model Using Cynomolgus Macaques

BACKGROUND

Trauma-induced hemorrhagic shock produces hemodynamic changes that often result in a systemic inflammatory response that can lead to multiple organ failure and death. In this prospective study, the pathophysiology of a nonhuman primate uncontrolled hemorrhagic shock model is evaluated with the goal of creating an acute systemic inflammatory syndrome response and a reproducible hemorrhage.

METHODS

Nonhuman primates were divided into 2 groups. A laparoscopic left hepatectomy was performed in groups A and B, 60% and 80%, respectively, resulting in uncontrolled hemorrhage. Resuscitation during the prehospital phase lasted 120 min and included a 0.9% saline bolus at 20 mL/kg. The hospital phase involved active warming, laparotomy, hepatorrhaphy for hemostasis, and transfusion of packed red blood cells (10 mL/kg). The animals were recovered and observed over a 14-day survival period with subsequent necropsy for histopathology.

RESULTS

Baseline demographics and clinical parameters of the two groups were similar. Group A (n = 7) underwent a 57.7% ± 2.4% left hepatectomy with a 33.9% ± 4.0% blood loss and 57% survival. Group B (n = 4) underwent an 80.0% ± 6.0% left hepatectomy with 56.0% ± 3.2% blood loss and 75% survival. Group B had significantly lower hematocrit (P < 0.05) for all postinjury time points. Group A had significantly elevated creatinine on postoperative day 1. Nonsurvivors succumbed to an early death, averaging 36 h from the injury. Histopathologic evaluation of nonsurvivors demonstrated kidney tubular degeneration.

CONCLUSIONS

Nonhuman primates displayed the expected physiologic response to hemorrhagic shock due to liver trauma as well as systemic inflammatory response syndrome with resultant multiple organ dysfunction syndrome and either early death or subsequent recovery. Our next step is to establish a clinically applicable nonhuman primate polytrauma model, which reproduces the prolonged maladaptive immunologic reactivity and end-organ dysfunction consistent with multiple organ failure found in the critically injured patient.

Myocardial Perfusion and Function Are Distinctly Altered by Sevoflurane Anesthesia in Diet-Induced Prediabetic Rats

Preservation of myocardial perfusion during surgery is particularly important in patients with increased risk for perioperative complications, such as diabetes. Volatile anesthetics, like sevoflurane, have cardiodepressive effects and may aggravate cardiovascular complications. We investigated the effect of sevoflurane on myocardial perfusion and function in prediabetic rats. Rats were fed a western diet (WD; n = 18) or control diet (CD; n = 18) for 8 weeks and underwent (contrast) echocardiography to determine perfusion and function during baseline and sevoflurane exposure. Myocardial perfusion was estimated based on the product of microvascular filling velocity and blood volume. WD-feeding resulted in a prediabetic phenotype characterized by obesity, hyperinsulinemia, hyperlipidemia, glucose intolerance, and hyperglycemia. At baseline, WD-feeding impaired myocardial perfusion and systolic function compared to CD-feeding. Exposure of healthy rats to sevoflurane increased the microvascular filling velocity without altering myocardial perfusion but impaired systolic function. In prediabetic rats, sevoflurane did also not affect myocardial perfusion; however, it further impaired systolic function. Diet-induced prediabetes is associated with impaired myocardial perfusion and function in rats. While sevoflurane further impaired systolic function, it did not affect myocardial perfusion in prediabetic rats. Our findings suggest that sevoflurane anesthesia leads to uncoupling of myocardial perfusion and function, irrespective of the metabolic state.

Comparative embryotoxicity of phenanthrene and alkyl-phenanthrene to marine medaka (Oryzias melastigma)

Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are the predominant form of PAHs in oil, comprising 85-95% of total PAHs. However, little attention has been paid to these chemicals in ecological risk assessment of marine oil spill. A comparative study of the toxic effects of phenanthrene and retene (7-isopropyl-1-methylphenanthrene, an alkyl-phenanthrene) on the early life stage of marine medaka (Oryzias melastigma) was conducted. Results showed that retene was significantly more toxic than phenanthrene, and marine medaka could be more sensitive to retene than some freshwater fishes. Retene had a higher excretion rate than phenanthrene during the larvae stage. Both of compounds resulted in developmental malformation of marine medaka embryos, with phenanthrene affecting on peripheral vascular system and yolk sac, while retene affecting on cardiac tissues. The toxicity of phenanthrene might be mainly related to its anesthetic effects, and that of retene might be related to the CYP1A-mediated toxicity of its metabolites.

Vascular aging and hemodynamic stability in the intraoperative period

The proportion of elderly people in the population is steadily increasing, and the inevitable consequence is that this subpopulation is more frequently represented in common medical procedures and surgeries. Understanding the circulatory changes that accompany the aging process is therefore becoming increasingly timely and relevant. In this short review, we discuss aspects of vascular control in aging that are particularly relevant in the maintenance of intraoperative hemodynamic stability. We subsequently review the effects of certain notable anesthetic agents with respect to the aging vasculature.

Effects of nitrous oxide on minimum alveolar concentration of desflurane in dogs

Effects of nitrous oxide (N2O) on minimum alveolar concentration (MAC) of desflurane were studied. For that purpose, 30 dogs were randomly allocated into two groups: desflurane group (GD) and N2O and desflurane group (GDN). GD animals received propofol to intubation, and 11.5V% of desflurane diluted in 100% O2. After 30 minutes, they received electric stimulus and if the animal did not react to stimulus, desflurane concentration was reduced by 1.5V%. This protocol was repeated at each 15 minutes, and stimulus was interrupted when voluntary reaction was observed. GDN dogs were submitted to diluent flow 30% O2 and 70% N2O. Desflurane's MAC; heart (HR) and respiratory (RR) rates; systolic, diastolic and mean arterial pressures (SAP, DAP, and MAP, respectively); end tidal carbon dioxide (ETCO2); oxyhemoglobin saturation (SpO2) and body temperature (T) were evaluated. In both groups increase in HR and ETCO2, and decrease in RR and T were associated with administration of the highest dose of desflurane. Blood pressures decreased 30 minutes after desflurane administration in GDN, and after this measurement the values increased. Reduction in desflurane's MAC was observed as well. It is concluded that N2O associated with desflurane reduced desflurane's MAC by 16% with increase in HR and respiratory depression.

Alterações hemodinâmicas e intracranianas em cães com hemorragia aguda, anestesiados com isofluorano

Estudaram-se possíveis alterações hemodinâmicas e intracranianas em cães submetidos à hemorragia aguda e anestesiados pelo isofluorano. Verificou-se também a influência do anestésico no mecanismo de auto-regulação cerebral. Utilizaram-se 20 cães adultos que foram induzidos à anestesia geral com isofluorano por máscara naso-oral a 3,5V% (volume %). Após a intubação orotraqueal, reajustou-se o vaporizador para 2,1V%. Induziu-se a hipovolemia retirando-se volume total de 35ml/kg de sangue. Avaliaram-se pressão intracraniana (PIC), temperaturas intracraniana (TIC) e corpórea (T), pressão de perfusão cerebral (PPC), pressões arteriais sistólica (PAS), diastólica (PAD) e média (PAM), freqüências cardíaca (FC) e respiratória (FR), índices cardíaco (IC) e sistólico (IS), pressão venosa central (PVC), pressão da artéria pulmonar (PAP), concentração de dióxido de carbono ao final da expiração (ETCO2) e saturação de oxihemoglobina (SpO2). Imediatamente após a hipovolemia, houve redução significativa da PIC, PPC, PAS, PAD, PAM, IC, IS e PAP. Após 10 minutos, houve aumento gradativo das médias, permanecendo neste patamar até o final do período experimental. Concluiu-se que a hemorragia aguda promoveu redução das variáveis hemodinâmicas, sendo possível verificar a ativação de mecanismos compensatórios. Além disso, houve redução da perfusão sangüínea e ativação do mecanismo de auto-regulação cerebral, conseqüentes à hipovolemia associada à anestesia com isofluorano.

Defects in cardiac function precede morphological abnormalities in fish embryos exposed to polycyclic aromatic hydrocarbons

Fish embryos exposed to complex mixtures of polycyclic aromatic hydrocarbons (PAHs) from petrogenic sources show a characteristic suite of abnormalities, including cardiac dysfunction, edema, spinal curvature, and reduction in the size of the jaw and other craniofacial structures. To elucidate the toxic mechanisms underlying these different defects, we exposed zebrafish (Danio rerio) embryos to seven non-alkylated PAHs, including five two- to four-ring compounds that are abundant in crude oil and two compounds less abundant in oil but informative for structure-activity relationships. We also analyzed two PAH mixtures that approximate the composition of crude oil at different stages of weathering. Exposure to the three-ring PAHs dibenzothiophene and phenanthrene alone was sufficient to induce the characteristic suite of defects, as was genetic ablation of cardiac function using a cardiac troponin T antisense morpholino oligonucleotide. The primary etiology of defects induced by dibenzothiophene or phenanthrene appears to be direct effects on cardiac conduction, which have secondary consequences for late stages of cardiac morphogenesis, kidney development, neural tube structure, and formation of the craniofacial skeleton. The relative toxicity of the different mixtures was directly proportional to the amount of phenanthrene, or the dibenzothiophene-phenanthrene total in the mixture. Pyrene, a four-ring PAH, induced a different syndrome of anemia, peripheral vascular defects, and neuronal cell death, similar to the effects previously described for potent aryl hydrocarbon receptor ligands. Therefore, different PAH compounds have distinct and specific effects on fish at early life history stages.