Hemodynamic and metabolic effects of ketamine anesthesia in the geriatric patient

Predictive model for post-induction hypotension in patients undergoing transcatheter aortic valve implantation: a retrospective observational study

PURPOSE

Post-induction hypotension (PIH) is an independent risk factor for prolonged postoperative stay and hospital death. Patients undergoing transcatheter aortic valve implantation (TAVI) are prone to develop PIH. This study aimed to develop a predictive model for PIH in patients undergoing TAVI.

METHODS

This single-center retrospective observational study included 163 patients who underwent TAVI. PIH was defined as at least one measurement of systolic arterial pressure <90 mmHg or at least one incident of norepinephrine infusion at a rate >6 µg/min from anesthetic induction until 20 min post-induction. Multivariate logistic regression analysis was performed to develop a predictive model for PIH in patients undergoing TAVI.

RESULTS

In total, 161 patients were analyzed. The prevalence of PIH was 57.8%. Multivariable logistic regression analysis showed that baseline mean arterial pressure ≥90 mmHg [adjusted odds ratio (aOR): 0.413, 95% confidence interval (95% CI): 0.193-0.887; p=0.023] and higher doses of fentanyl (per 1-µg/kg increase, aOR: 0.619, 95% CI: 0.418-0.915; p=0.016) and ketamine (per 1-mg/kg increase, aOR: 0.163, 95% CI: 0.062-0.430; p=0.002) for induction were significantly associated with lower risk of PIH. A higher dose of propofol (per 1-mg/kg increase, aOR: 3.240, 95% CI: 1.320-7.920; p=0.010) for induction was significantly associated with higher risk of PIH. The area under the curve (AUC) for this model was 0.802.

CONCLUSION

The present study developed predictive models for PIH in patients who underwent TAVI. This model may be helpful for anesthesiologists in preventing PIH in patients undergoing TAVI.

Bipolar Disorder Among Older Adults: Newer Evidence to Guide Clinical Practice

The term older-age bipolar disorder (OABD) refers to patients with bipolar disorder who are ages 50 and older. Research findings suggest important differences, including the attenuation of manic symptoms with age and the occurrence of multiple somatic comorbid conditions. Although the pharmacological treatment of OABD is fairly similar, adverse effects, somatic comorbidity, and drug-drug interactions are more common. Lithium is effective in treating OABD and may have the potential to be neuroprotective. Anticonvulsants and second-generation antipsychotics have a growing evidence supporting their use in treating OABD. Behavioral intervention can be a helpful adjunct to pharmacological treatment. Clinicians and health care systems need to be prepared to provide care and services to individuals with bipolar disorder throughout the life span. Although older adults have typically been excluded from bipolar disorder RCTs, emerging efforts organized by global advocates and harnessing teams of clinicians and scientists have the potential to advance care.

Procedural sedation analgesia in the elderly patient

Elderly patients are perceived as a high-risk group for procedural sedation. Procedural sedation analgesia (PSA) is generally safe in older adults. What is not acceptable is undertreating pain or inadequately sedating a stable patient. All the usual precautions should be taken. One should consider any comorbidities that could make the patient more at risk of adverse reactions or complications. Older patients may be at higher risk for oxygen desaturation, but they usually respond quickly to supplemental oxygen. Geriatric patients usually require lower doses of medications. They tend to be more sensitive to medications, with slower metabolism, less physiologic reserve to handle side effects, and a smaller volume of distribution. The use of drugs for sedation in elderly patients requires careful consideration of their age-related changes in physiology and pharmacokinetics. The choice of drug should be based on the patient's medical condition, comorbidities, and potential adverse effects. Moreover, the administration should be done by trained personnel with close monitoring of vital signs and level of consciousness to prevent complications such as respiratory depression.

Effect of Ketamine on Cardiovascular Function During Procedural Sedation of Adults

INTRODUCTION

 Ketamine is commonly used in emergency department procedural sedation. Mild to moderate transient increases in blood pressure, heart rate, and cardiac output are common due to ketamine causing an increase in sympathetic activity. There is a concern that these physiological changes could result in an increased myocardial oxygen demand that may exacerbate underlying cardiac disease.

METHODS

 Convenience sample of patients older than 50 years receiving ketamine for procedural sedation in the emergency department was used (n = 31). Patients were selected to receive ketamine based on provider discretion. Primary outcome was incidence of new myocardial ischemia apparent on an electrocardiogram (ECG). ECGs were obtained prior to sedation and during the sedation approximately one minute after administration of ketamine. ECGs were reviewed by a board-certified emergency medicine physician and a board-certified cardiologist.

RESULTS

 New onset ischemia was found in 9.7% (3/31) of ECGs. Of these, one was in a patient who had previously received ketamine without evidence of ischemia on the repeat ECG. There were no statistically significant differences between the groups. Evidence of ischemia on ECG did not impact patient disposition.

CONCLUSIONS

 Ketamine is a useful medication in procedural sedation; however, careful attention should be made in patient selection when ketamine is the desired agent. Consideration might be made in using the lowest possible dose of ketamine to obtain adequate sedation in order to hopefully lessen the occurrence of ECG changes suggestive of myocardial ischemia. Based on this small sample, single-site study, no evidence of statistically or clinically significant ischemia was seen with the use of ketamine for procedural sedation. Ketamine remains a safe medication option in adults undergoing procedural sedation.

Geriatric Pharmacology: An Update

An aging worldwide population demands that anesthesiologists consider geriatrics a unique subset of patients requiring customization of practice. This article reviews the current literature investigating physiologic changes of the elderly that affect pharmacokinetics and pharmacodynamics. Changes in drug absorption, distribution, metabolism, and excretion are discussed as well as the ultimate effects of medications. Implications for practice regarding specific anesthetic and analgesic drugs are addressed. Despite the immense body of research that contributes to understanding of geriatric pharmacology, elderly patients often are excluded from rigorous research trials, and further scientific investigation to inform best practices for this group of patients is needed.

Adverse events associated with ketamine for procedural sedation in adults

STUDY OBJECTIVES

Ketamine is widely used as a procedural sedation agent in pediatrics, where its safety and efficacy are supported by numerous studies. Emergency physicians use ketamine infrequently in adults, as it is believed to have a more significant side effect profile in this population. However, adult data on ketamine use in the emergency medicine literature are sparse. Our objective was to determine ketamine's adverse effect profile in adults when used for procedural sedation.

METHODS

We performed a literature review based on adverse effect research methodology recommendations. PubMed, EMBASE, TOXNET, and a variety of specialized databases were queried without regard to publication date or language. Experts were contacted to locate additional data. Inclusion criteria included adult study; ketamine used to facilitate the performance of painful procedures; dose of at least 1 mg/kg intravenous or at least 2 mg/kg intramuscular; original data and adverse events reported; spontaneously breathing patient, and no continuous cotherapies. Studies that met inclusion criteria were abstracted onto structured forms and their results qualitatively summarized.

RESULTS

Of the 5512 unique citations that were evaluated, 87 met criteria for inclusion. Most studies were performed in the 1970s and published in the anesthesia literature. Contexts, end points, and methodological quality varied widely across studies. Ketamine reliably produces conditions that facilitate the performance of painful procedures. Pharyngeal reflexes are generally preserved and cardiovascular tone stimulated, including a rise in blood pressure and myocardial oxygen demand. Laryngospasm and airway obstruction are reported, and though ketamine is a respiratory stimulant, a brief period of apnea around the time of injection is common. Reports of significant cardiorespiratory adverse events are rare, despite ketamine's frequent use in austere, poorly monitored settings. Dysphoric emergence phenomena occur in 10% to 20% of cases; sedating medications are effective in preventing and managing these reactions.

CONCLUSION

When ketamine is used for procedural sedation in adults, emergence phenomena occur in 10% to 20% of patients. Although providers must be prepared to recognize and manage airway obstruction, cardiorespiratory adverse events are rare and typically do not affect outcomes.

Steady-state pharmacokinetics and pharmacodynamics of CHF3381, a novel antineuropathic pain agent, in healthy subjects

AIMS

To evaluate the safety, tolerability, pharmacokinetic and pharmacodynamic profiles of CHF3381, a dual NMDA and MAO-A inhibitor, after multiple oral doses in healthy subjects.

METHODS

Forty-eight young males received CHF3381 at doses of 100 mg twice daily, 200 mg twice daily, 400 mg twice daily or placebo for 2 weeks according to a double-blind, randomized, parallel group design. Plasma and urine concentrations of the parent drug and of two major metabolites (CHF3567 and 2-aminoindane) were measured over time. MAO-A activity in plasma was estimated by measuring plasma concentrations of 3,4-dihydroxyphenylglycol. Sustained attention, memory and sedation were assessed throughout the study with standard psychometric tests.

RESULTS

Most of the adverse events were mild in intensity, with dose regimens of 100 mg twice daily and 200 mg twice daily being indistinguishable from placebo. After 400 mg twice daily, the most frequent adverse events were mild dizziness, asthenia and insomnia. At steady-state, 400 mg twice daily slightly increased supine heart rate (+ 9 +/- 2 beats min(-1)) and diastolic blood pressure (+6 +/- 2 mmHg) compared with placebo. There were no dose-dependent or consistent effects of CHF3381 on attention, motor co-ordination or memory, but 400 mg twice daily significantly decreased alertness compared with placebo. Plasma concentrations of CHF3381 peaked at around 3 h and were dose-proportional. The elimination half-life of CHF3381 was estimated to be 4-6 h. At steady-state, significant CHF3381 plasma concentrations were detected at predose with a modest accumulation (1.3-1.5 times), showing that the drug given twice daily is active over the entire 24 h period. Plasma concentrations of CHF3567 and of 2-aminoindane were also proportional to the dose of CHF3381. CHF3381 dose-dependently inhibited MAO-A activity with peak effects at steady-state of 27 +/- 4%, 46 +/- 2% and 65 +/- 5% after 100 mg twice daily, 200 mg twice daily and 400 mg twice daily, respectively. There were no significant effects of CHF3381 on attention (rapid visual information processing), motor co-ordination (body sway) or memory (learning memory task) at any of the doses. At steady-state, there was a significant decrease in alertness (Bond & Lader visual analogue scale) in the 400 mg twice daily group compared with placebo.

CONCLUSIONS

A twice daily regimen of CHF3381 appears to be adequate from a pharmacokinetic and pharmacodynamic perspective. Plasma concentrations reached with 400 mg twice daily exceeded those observed in animals receiving pharmacologically active doses in chronic pain models.

Safety, pharmacokinetics, and pharmacodynamics of CHF 3381, a novel N-methyl-D-aspartate antagonist, after single oral doses in healthy subjects

A double-blind, randomized, placebo-controlled study was performed to assess the safety, tolerability, and pharmacokinetics of single oral doses of CHF 3381 in 56 young healthy male volunteers. The central nervous system effects of CHF 3381 were also evaluated, as well as the effect of food on the rate and extent of CHF 3381 absorption. Seven doses of CHF 3381 (25, 50, 100, 200, 300, 450, and 600 mg) were evaluated in an escalating order. At each dose level, 6 subjects were given CHF 3381, and 2 subjects were given placebo. Safety and tolerability evaluation included adverse events, physical examination, vital functions, electrocardiogram, laboratory tests, and 24-hour Holter (100-mg and 450-mg dose panels). Plasma and urinary concentrations of CHF 3381 and its two main metabolites (CHF 3567 and 2-aminoindane) were measured with a validated high-performance liquid chromatography method. Central nervous system effects were evaluated with the simple reaction time (SRT); learning memory task (LMT); Bond & Lader Visual Analog Scale for alertness, contentedness, and calmness; Addiction Research Center Inventory (ARCI); and electroencephalogram. There were no serious adverse events; the most frequent adverse events were dizziness, abnormal thinking, and asthenia. The number of adverse events with moderate intensity increased sharply with the dose, with no or few events up to 450 mg and 17 events with 600 mg. Therefore, 600 mg was defined as the maximum tolerated dose. There were no significant treatment effects on cardiovascular function and electrocardiogram parameters at any CHF 3381 dose or on oral temperature or laboratory tests. There were no clinically significant changes in laboratory variables. CHF 3381 was absorbed rapidly (tmax = 0.5-2 h) and cleared from plasma with a half-life of 3 to 4 hours. Plasma levels of CHF 3381 and its two major metabolites were found to be proportional to the dose. 2-Aminoindane formed slowly and reached much lower concentrations compared to the parent compound and the other metabolite (CHF 3567). Within 48 hours after dosing, 2% to 6% of the administered dose was found in the urine as unchanged drug, about 50% to 55% as the acid derivative (CHF 3567), and 2% to 3% as 2-aminoindane. Ingestion of food did not affect the extent of absorption of the drug, while the rate of absorption was considerably reduced (tmax = 4 h). No significant effects of CHF 3381 were observed on attention (SRT) or memory (LMT). Visual analog scales revealed a decreasing effect of CHF 3381 on alertness at 1 hour that reached statistical significance at 300 and 600 mg. EEG spectral analysis revealed minor decreasing effects of the 200-mg dose on total electric power measured at 2 hours. A stimulant effect was detected by the ARCI scale 24 hours after the 300-mg dose and might be related to the slow formation of the 2-aminoindane metabolite. In conclusion, this study has shown that the maximum tolerated dose of CHF 3381 after single oral administration in young healthy male volunteers is 600 mg. CHF 3381 displays linear pharmacokinetics in the dose range of 25 to 600 mg. The compound is rapidly absorbed and cleared from plasma with a half-life of 3 to 4 hours. The ingestion of food seems to not affect the extent of absorption of the drug. Minor effects on the central nervous system were detected at doses equal to or greater than 300 mg.

Clinical experience with excitatory amino acid antagonist drugs

BACKGROUND

Excitotoxic damage due to excess release of neuronal glutamate is hypothesized to play a pivotal role in the pathogenesis of focal cerebral ischemia. Drugs that antagonize excitatory amino acid function are consistently neuroprotective in preclinical models of stroke, and many are now entering clinical trials.

SUMMARY

Antagonists of the N-methyl-D-aspartate (NMDA) receptor are furthest advanced in clinical development for stroke. Both noncompetitive (aptiganel hydrochloride, dextrorphan) and competitive (selfotel, d-CPPene) antagonists have undergone tolerability studies in acute stroke and traumatic brain injury. These agents all cause a similar spectrum of neuropsychological symptoms, and several have important cardiovascular effects. Other modulatory sites on the NMDA receptor complex, notably the polyamine and magnesium ion sites, are also the subject of clinical trials. Glycine site antagonists are in early clinical development. Non-NMDA glutamate receptor antagonists remain in preclinical study. Neuroprotection by agents that block glutamate release in vitro may be due to sodium channel blockade in vivo, but some agents (619C89) exhibit neurological effects similar to NMDA antagonists in stroke. The therapeutic index is unknown for different drugs but may be determined by cardiovascular effects, especially hypotension, which may be detrimental after stroke.

CONCLUSIONS

Excitatory amino acid antagonists are in advanced development in the treatment of stroke and traumatic brain injury. A similar pattern of side effects is apparent with the majority of agents. However, cardiovascular effects may ultimately define therapeutic index for each drug.

Ketamine prevents ischemic neuronal injury

The dissociative anesthetic ketamine hydrochloride antagonizes the excitotoxic action of excitatory amino acids in the central nervous system. Proposals that the excitatory amino acid neurotransmitters may become excitotoxic and contribute to the pathophysiology of ischemic brain injury prompted us to examine ketamine in a model of global cerebral ischemia in gerbils. Pretreatment with anesthetic doses of ketamine ameliorated in a dose-dependent manner both behavioral and histopathological assessments of ischemic neuronal injury. These neuroprotective effects are proposed to result from a specific antiexcitotoxic rather than general anticonvulsant drug action. There may be clinical situations in which the neuroprotective actions of ketamine would be of therapeutic importance.

A comparison between propofol and ketamine for anaesthesia in the elderly. Haemodynamic effects during induction and maintenance

The haemodynamic effects of propofol and ketamine were studied in two groups of eight randomly allocated elderly patients (mean age 85.8 years) anaesthetised for hip replacement. Group 1 patients patients received propofol 1 mg/kg by intravenous bolus for induction and 0.1 mg/kg/minute by continuous infusion for maintenance. Group 2 patients received ketamine 1.5 mg/kg by intravenous bolus as induction dose and 50 micrograms/kg/minute by continuous infusion for maintenance. All patients breathed spontaneously via a facemask at FIO2 1.0. Haemodynamic status was established before induction and at 1, 3, 5, 10 and 15 minutes after induction. Arterial pressure and cardiac output decreased slightly in group 1 but heart rate, right atrial pressure and pulmonary arterial pressure remained unchanged. Myocardial oxygen consumption showed a significant decrease of 27%. There was a significant increase in blood pressure and pulmonary capillary wedge pressure (by 97%) in group 2. Cardiac output and systemic vascular resistance remained unchanged whereas myocardial oxygen consumption showed a very significant increase of 100%.

[Propofol or ketamine in anesthesia of the very old patient. Study of the hemodynamic effects during induction]

The haemodynamic changes following anaesthesia for hip surgery in 16 very old ASA II or III patients (mean age 85.8 +/- 5 years) were studied. Patients were randomly assigned to two groups: group I 1 mg X kg-1 propofol, group II 1.5 mg X kg-1 ketamine. After injection, the patients were left spontaneously breathing oxygen, and were assisted when apneic. Haemodynamic measures with a Swan-Ganz catheter and thermodilution cardiac output calculator were made before and 1, 3, 5, 10 and 15 min after anaesthetic induction. The two groups were similar in age, weight and mean arterial pressure, but statistically different for some haemodynamic parameters (Ppa, Ppw, CI). In group I, arterial pressure fell significantly (-17%) in the first minute and continued to fall (-15%) until the 15th min. Heart rate remained unchanged: right atrial and pulmonary pressures were not changed; cardiac index fell slightly and MVO2 estimated by the triple product fell (-27%) as soon as propofol was infused. There was no clinical sign of cardiac failure. In group II, arterial pressure increased significantly, and heart rate decreased; pulmonary capillary wedge pressure increased (+93% after the 3rd min) and cardiac index was unchanged. The ventricular function curve was shifted to the right, suggesting a decrease in inotropism. Systemic vascular resistances were steady. MVO2 increased twofold, mainly due to the rise in pulmonary capillary wedge pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of ketamine on intracranial pressure during haemorrhagic shock under the conditions of both spontaneous breathing and controlled ventilation

Seventeen piglets of both sexes, seven with O2/air-buprenorphine anaesthesia and controlled ventilation, and ten unanaesthetized animals with normal, spontaneous respiration, were used for the study. The intracranial pressure of both groups of animals was raised by insufflation of an epidural balloon and the arterial blood pressure was reduced to approximately 70% of the original value by controlled haemorrhage. 0.5 mg/kg body weight of ketamine was given intravenously, followed by a further dose of 2.0 mg/kg body weight of ketamine five minutes later. Both ketamine doses led to a significant rise in the intracranial pressure of those animals breathing spontaneously (31.8 mm Hg to 39.1 mm Hg). In contrast, the ventilated animals showed a significant reduction in intracranial pressure. No changes in arterial PCO2 were observed in this group, while those piglets breathing spontaneously had dangerous PCO2 rises. At both ketamine doses a significant correlation could be found between the PCO2 and the intracranial pressure.