Propofol in elderly high risk patients. A comparison of haemodynamic effects with thiopentone during induction of anaesthesia

The effect of cardiac output on the pharmacokinetics and pharmacodynamics of propofol during closed-loop induction of anesthesia

BACKGROUND AND OBJECTIVE

Intraoperative hemodynamic stability is essential to safety and post-operative well-being of patients and should be optimized in closed-loop control of anesthesia. Cardiovascular changes inducing variations in pharmacokinetics may require dose modification. Rigorous investigational tools can strengthen current knowledge of the anesthesiologists and support clinical practice. We quantify the cardiovascular response of high-risk patients to closed-loop anesthesia and propose a new application of physiologically-based pharmacokinetic-pharmacodynamic (PBPK-PD) simulations to examine the effect of hemodynamic changes on the depth of hypnosis (DoH).

METHODS

We evaluate clinical hemodynamic changes in response to anesthesia induction in high-risk patients from a study on closed-loop anesthesia. We develop and validate a PBPK-PD model to simulate the effect of changes in cardiac output (CO) on plasma levels and DoH. The wavelet-based anesthetic value for central nervous system monitoring index (WAV_CNS) is used as clinical end-point of propofol hypnotic effect.

RESULTS

The median (interquartile range, IQR) changes in CO and arterial pressure (AP), 3 min after induction of anesthesia, are 22.43 (14.82-36.0) % and 26.60 (22.39-35.33) % respectively. The decrease in heart rate (HR) is less marked, i.e. 8.82 (4.94-12.68) %. The cardiovascular response is comparable or less enhanced than in manual propofol induction studies. PBPK simulations show that the marked decrease in CO coincides with high predicted plasma levels and deep levels of hypnosis, i.e. WAV_CNS < 40. PD model identification is improved using the PBPK model rather than a standard three-compartment PK model. PD simulations reveal that a 30% drop in CO can cause a 30% change in WAV_CNS.

CONCLUSIONS

Significant CO drops produce increased predicted plasma concentrations corresponding to deeper anesthesia, which is potentially dangerous for elderly patients. PBPK-PD model simulations allow studying and quantifying these effects to improve clinical practice.

Prediction of hemodynamic fluctuations after induction of general anesthesia using propofol in non-cardiac surgery: a retrospective cohort study

Background

Although propofol is a common anesthetic agent for the induction of general anesthesia, hemodynamic fluctuations are occasionally prominent during induction/intubation. The aims of this study were to determine the influential factors on enhanced hemodynamic fluctuation and to establish a prediction formula to quickly determine the dose of propofol to protect against hemodynamic fluctuations.

Methods

This retrospective cohort study patients (n = 2097) were 18 years or older. They underwent general anesthesia induction using propofol and orotracheal intubation for non-cardiac surgery at Kyushu University Hospital during April 2015 to March 2016. Preoperative patient clinical information was collected from anesthesia preoperative evaluation records. Intraoperative data were obtained from computerized anesthesia records. If patients’ post-induction mean arterial blood pressure (MAP) decreased or increased 30% or more from their pre-induction MAP, they were determined to have enhanced hemodynamic fluctuations. Unconditional logistic regression was used to assess the adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Structural equation modeling (SEM) was conducted to simultaneously examine the direct and indirect effect (path coefficient = r) of potential variables.

Results

In the SEM analysis, age was significantly associated with enhanced hemodynamic fluctuations (adjusted odds ratio = 1.008, 95% CI = 1.001–1.015, P = 0.03). Age (path coefficient (r) = − 0.0113, 95% CI = − 0.0126–0.010, P < 0.001), American Society of Anesthesiologists physical status (ASA-PS) (r = − 0.0788, 95% CI = − 0.1431–0.0145, P = 0.02), sex (r = 0.057, 95% CI = 0.0149–0.9906, P = 0.01), and fentanyl dose (r = 0.1087, 95% CI = 0.0707–0.1467, P < 0.001) influenced the dose of propofol in induction. The prediction formula of “Propofol dose (mg) = [2.374 – 0.0113 × age (year) – 0.0788 (if ASA-PS 3 or 4) + 0.057 (if female) + 0.1087 × fentanyl dose (μg/kg)] × body weight (kg)” was derived.

Conclusions

Age was associated with hemodynamic fluctuations in induction. Although the prediction formula is considered to be acceptable, future studies validating whether it can decrease patients’ risk of enhanced hemodynamic fluctuations in clinical situations are necessary.

Propofol Use in the Elderly Population: Prevalence of Overdose and Association With 30-Day Mortality

PURPOSE

Geriatric patients are more sensitive to the anesthetic effects of propofol and its adverse effects, such as hypotension, than is the general population; thus, a reduced dose (1-1.5 mg/kg) is recommended for the induction of anesthesia. The extent to which clinicians follow established dosing guidelines has not been well described. Therefore, we investigated the prevalence of propofol overdose in the elderly population to determine whether propofol overdose occurs and is associated with increased hypotension and 30-day mortality.

METHODS

In this retrospective study in patients who received propofol for the induction of general anesthesia, data on demographic characteristics, preoperative medications, intraoperative management, and 30-day mortality were collected. The dose of propofol used for the induction of anesthesia and the median blood pressure in the pre- and immediate postinduction periods were determined. Hypotension was defined as either: (1) a decrease in mean arterial pressure (MAP) of >40% concurrent with a MAP of <70 mm Hg; or (2) a MAP of <60 mm Hg.

FINDINGS

A total of 17,540 patients were included in the analysis; 4033 (23.0%) were aged >65 years. The median (interquartile range) propofol dose in the group aged >65 years was 1.8 (1.4-2.2) mg/kg, above the recommended dose, in comparison to 2.2 (1.9-2.5) mg/kg in younger patients. On multivariate analysis, increased propofol dose was associated with increased postinduction hypotension, especially in patients over 70 years of age, but not 30-day mortality.

IMPLICATIONS

Older patients received greater-than-recommended doses of propofol for induction, which may have led to significant dose-dependent hypotension. Despite this finding, the dose of propofol for induction was not independently associated with a greater 30-day mortality rate. More education regarding geriatric concerns is needed for encouraging anesthesiologists to tailor the plan for anesthesia in geriatric patients. However, overall postsurgical mortality is a function of preoperative risk and type surgical procedure.

Onset time and haemodynamic response after thiopental vs. propofol in the elderly: a randomized trial

BACKGROUND

The induction dose of hypnotic agents should be reduced in the elderly, but it is not well studied whether thiopental or propofol should be preferred in this group of patients. The aim of this study was to compare onset time, hypnosis level and the haemodynamic response after thiopental vs. propofol for induction of anaesthesia. Our primary hypothesis was that in the elderly, thiopental had a shorter onset time than propofol, defined as time to bispectral index (BIS) <50.

METHODS

In this randomized and double-blinded study, we included 78 patients. Patients were eligible, if they were scheduled for elective surgery with general anaesthesia and aged 60 or older. Patients received alfentanil 10 μg/kg and either thiopental 2.5 mg/kg or propofol 1.0 mg/kg, and depth of anaesthesia was determined with BIS the following 120 s along with clinical assessment of anaesthetic depth. The primary endpoint was the time from start of injection of the hypnotic to a BIS value below 50.

RESULTS

Time to BIS <50 was significantly shorter in patients receiving thiopental, where onset time was 52 s (median value) compared with 65 s in the propofol group (P=0.01). Mean arterial pressure decreased 25.6 mmHg in the propofol group and 15.6 mmHg in the thiopental group (P=0.003) within 120 s. Heart rate decreased 9.1 b.p.m. within 120 s in the patients receiving propofol compared with a decrease of 5.1 b.p.m. in patients receiving thiopental (P=0.04).

CONCLUSION

Thiopental was found to have a faster onset than propofol in elderly surgical patients.

Scandinavian clinical practice guidelines on general anaesthesia for emergency situations

Emergency patients need special considerations and the number and severity of complications from general anaesthesia can be higher than during scheduled procedures. Guidelines are therefore needed. The Clinical Practice Committee of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine appointed a working group to develop guidelines based on literature searches to assess evidence, and a consensus meeting was held. Consensus opinion was used in the many topics where high-grade evidence was unavailable. The recommendations include the following: anaesthesia for emergency patients should be given by, or under very close supervision by, experienced anaesthesiologists. Problems with the airway and the circulation must be anticipated. The risk of aspiration must be judged for each patient. Pre-operative gastric emptying is rarely indicated. For pre-oxygenation, either tidal volume breathing for 3 min or eight deep breaths over 60 s and oxygen flow 10 l/min should be used. Pre-oxygenation in the obese patients should be performed in the head-up position. The use of cricoid pressure is not considered mandatory, but can be used on individual judgement. The hypnotic drug has a minor influence on intubation conditions, and should be chosen on other grounds. Ketamine should be considered in haemodynamically compromised patients. Opioids may be used to reduce the stress response following intubation. For optimal intubation conditions, succinylcholine 1-1.5 mg/kg is preferred. Outside the operation room, rapid sequence intubation is also considered the safest method. For all patients, precautions to avoid aspiration and other complications must also be considered at the end of anaesthesia.

The pharmacology of anesthetic drugs in elderly patients

Elderly patients are more sensitive to anesthetic drugs than younger patients. This increased sensitivity has a pharmacokinetic basis if the dose produces a higher drug concentration in an elderly patient than in a younger patient. The increased sensitivity has a pharmacodynamic basis if the same concentration produces a more profound drug effect in elderly patients. This article reviews the mechanisms of increased sensitivity of elderly patients to opioids, hypnotics, amnestica, and muscle relaxants.

Comparative evaluation of TIVA with propofol-fentanyl and thiopental-sevoflurane anesthesia using laryngeal mask airway for diagnostic bronchoscopy

PURPOSE

Diagnostic bronchoscopy is performed under general anesthesia in our hospital. This study was designed to determine whether total intravenous anesthesia (TIVA) with propofol-fentanyl provides more stable hemodynamics using a laryngeal mask airway (LMA) for diagnostic bronchoscopy than thiopental-sevoflurane anesthesia.

METHODS

Sixty patients scheduled for diagnostic bronchoscopy were randomly assigned to two groups. TIVA with propofol-fentanyl was induced with intravenous fentanyl 2 μg·kg^-1 and propofol 2 mg·kg^-1 and maintained with continuous infusion of propofol with fentanyl. Thiopental-sevoflurane anesthesia was induced with thiopental 5 mg·kg^-1 and maintained with N₂O/O₂/sevoflurane. Insertion of the LMA was facilitated with vecuronium 0.1 mg·kg^-1 i.v. in both groups. Ventilation was controlled, and administration of propofol and sevoflurane was continued until the end of the procedure. The LMA was removed when the patient was able to open his or her mouth.

RESULTS

During TIVA, the mean arterial pressure and rate pressure product decreased significantly from induction until 20 min after the start of the procedure, and they were maintained at around 70 mmHg and 7000, respectively, during the procedure. There were no significant differences in heart rate,[Formula: see text] and[Formula: see text]. In thiopental-sevoflurane anesthesia, the mean arterial pressure and rate pressure product decreased significantly after induction and increased significantly from insertion of the LMA until removal of the LMA. Heart rate increased significantly after insertion of the LMA, insertion of the bronchoscope, and removal of the LMA. There were no significant differences in[Formula: see text] and[Formula: see text].

CONCLUSION

TIVA with propofol-fentanyl in conjunction with an LMA performs better than thiopental-sevoflurane anesthesia for diagnostic bronchoscopy because of its superior maintenance of cardiovascular stability.

[Use of Diprivan in the elderly]

Propofol may be safely used in elderly patients provided that: hypovolaemia is corrected prior to procedure; a decrease in blood pressure of more than 25 per cent of the baseline value is treated with a sympathomimetic drug (e.g. ephedrine); bradycardia below 55 b.min-1 using atropine; not more than 5 mL (50 mg) of propofol are injected per minute; the induction dose does not exceed 1.5 mg.kg-1, with a possible further dose of 0.2 to 0.4 mg.kg-1, immediately prior to intubation; opioids are not administered before stabilization of blood pressure during the period proceeding intubation; nitrous oxide and halogenated anaesthetics are not used as long as haemodynamic parameters are unstable; the dose of beta-blockers, ACE inhibitors and calcium antagonists is decreased or the drugs discontinued prior to surgery, depending upon their effect and their duration of action, except in cases of unstable angina or severe hypertension.

The use of propofol in a child with hepatitis A

Propofol was used for the induction and maintenance of anaesthesia in a 4-year-old girl with hepatitis A and haematemesis. The anaesthetic was uneventful with no postoperative sequelae.

Sedation for bronchofiberoscopy: comparison between propofol infusion and intravenous boluses of fentanyl and diazepam

Two methods of sedation were evaluated in unpremedicated patients undergoing elective bronchofiberoscopy. The patients were randomly allocated to receive either propofol infusion 1 mg kg-1 h-1 preceded by a 1 mg kg-1 bolus (15 patients) (the propofol group) or intravenous fentanyl 1 micrograms kg-1 and diazepam 0.05 mg kg-1 (15 patients) (the fentanyl+diazepam group). Thirteen patients were treated twice during the study period and sedated with both methods (the first treatment according to random order and the second with the method not used on the first occasion). A topical anaesthetic was applied to the selected nostril with two cotton swabs soaked in 4% lidocaine. Epiglottis, vocal cords, trachea and bronchi were anaesthetized by spraying 4% lidocaine through the working channel of the fiberoscope as the instrument was advanced. The patients in the propofol group were more sedated than those in the fentanyl+diazepam groups (P less than 0.01). The working conditions were the same. After sedation, respiratory frequency decreased only in the fentanyl+diazepam group (P less than 0.05). Before sedation, haemoglobin saturation of oxygen was 95 +/- 2% (mean +/- s.d.) in the propofol group and 94 +/- 3% in the fentanyl+diazepam group. Immediately before the start of bronchofiberoscopy, it was 89 +/- 4% and 90 +/- 3%, respectively. The decrease was statistically significant in both groups (P less than 0.001). After sedation, systolic arterial pressures (SAP) decreased in both groups (P less than 0.01). Compared to values immediately before starting bronchofiberoscopy, SAP increased during the procedure in both groups (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The haemodynamic effects of bronchoscopy. Comparison of propofol and thiopentone with and without alfentanil pretreatment

The haemodynamic response to bronchoscopy under general anaesthesia was investigated. Forty patients were allocated at random to receive either thiopentone or propofol; half the patients in each group received in addition 18 micrograms/kg of alfentanil one minute before induction of anaesthesia. The heart rate, noninvasive blood pressure and Holter ECG was monitored in all patients. Significant increases in heart rate (p less than 0.05), systolic and diastolic arterial pressures (p less than 0.01) occurred in the thiopentone only group, following bronchoscopy. Systolic and diastolic arterial pressure decreased in patients receiving thiopentone plus alfentanil, following induction of anaesthesia and laryngoscopy (p less than 0.05). No significant haemodynamic changes were seen in either of the groups which received propofol. ST segment changes on subsequent Holter analysis were seen in four patients, but there were no significant differences between the groups. Anaesthesia with propofol alone provides adequate haemodynamic stability for bronchoscopy and the addition is superfluous.

[General anesthesia in the elderly]

Physiologic and pathologic changes due to ageing should be taken in account for the preoperative evaluation and peroperative management of geriatric patients. Pharmacokinetic changes ed to reduce the doses of intravenous agents by 50%. MAC of inhalational agents is decreased by 25 to 75%. Pharmacodynamic deleterious effects are limitative in the choice of some drugs. Cardiocirculatory and pulmonary functions need specific, if possible non invasive monitoring, during surgery, recovery and the early postoperative days.