Hemodynamics and tissue oxygenation during balanced anesthesia with a high antinociceptive contribution: an observational study

Effects of esmolol infusion on cardiovascular parameters and quality of general anaesthesia in younger and older patients

Background: Esmolol is a cardioselective b-adrenergic antagonist that is used during general anaesthesia to blunt the sympathetic reflex tachycardia and hypertension. The aim of the study was to investigate whether the potential beneficial and adverse effects of esmolol differ depending on the patient age. Methods: A total of 50 ASA I/II patients scheduled for elective upper abdominal surgery were divided in two groups: younger (patients aged up to 35 years) and older (patients older than 65). After premedication with Diazepam, they were infused with esmolol during the first 5 min at a rate of 0.3 mg/kg/min and 0.1 mg/kg/min thereafter. Anaesthesia was induced with thiopental sodium 3-5 mg/kg intravenously (iv) and fentanyl 1.5 µg/kg IV. Tracheal intubation was facilitated with suxamethonium 1-2 mg/kg IV. Long-term neuromuscular blockade was induced with pancuronium bromide 0.07 mg/kg IV bolus and maintained with incremental IV boluses of 0.01 mg/ kg. Inhalational anaesthesia was maintained with a mixture of oxygen and nitrous oxide (O2 /N2 O) 2 : 1. Results: The systolic blood pressure remained constant during the intubation phase in the group of older patients, at the same time being around 89 % of the pre-induction values, while in younger patients it rose up to 100 %. During the same phase of anaesthesia, the diastolic blood pressure in older patients remained at about 91 %, while in younger patients it rose up to 107 % of the pre-induction values. The consumption of drugs and the speed and quality of the recovery from anaesthesia did not differ between the two groups of patients. Conclusion: Infusion of esmolol contributes to the concept of general balanced anaesthesia in elective patients scheduled for upper abdominal surgery equally in younger and older patients.

Improved haemodynamic stability and cerebral tissue oxygenation after induction of anaesthesia with sufentanil compared to remifentanil: a randomised controlled trial

BACKGROUND

Balanced anaesthesia with propofol and remifentanil, compared to sufentanil, often decreases mean arterial pressure (MAP), heart rate (HR) and cardiac index (CI), raising concerns on tissue-oxygenation. This distinct haemodynamic suppression might be attenuated by atropine. This double blinded RCT, investigates if induction with propofol-sufentanil results in higher CI and tissue-oxygenation than with propofol-remifentanil and if atropine has more pronounced beneficial effects on CI and tissue-oxygenation in a remifentanil-based anaesthesia.

METHODS

In seventy patients scheduled for coronary bypass grafting (CABG), anaesthesia was induced and maintained with propofol target controlled infusion (TCI) with a target effect-site concentration (Cet) of 2.0 μg ml- 1 and either sufentanil (TCI Cet 0.48 ng ml- 1) or remifentanil (TCI Cet 8 ng ml- 1). If HR dropped below 60 bpm, methylatropine (1 mg) was administered intravenously. Relative changes (∆) in MAP, HR, stroke volume (SV), CI and cerebral (SctO2) and peripheral (SptO2) tissue-oxygenation during induction of anaesthesia and after atropine administration were analysed.

RESULTS

The sufentanil group compared to the remifentanil group showed significantly less decrease in MAP (∆ = - 23 ± 13 vs. -36 ± 13 mmHg), HR (∆ = - 5 ± 7 vs. -10 ± 10 bpm), SV (∆ = - 23 ± 18 vs. -35 ± 19 ml) and CI (∆ = - 0.8 (- 1.5 to - 0.5) vs. -1.5 (- 2.0 to - 1.1) l min- 1 m- 2), while SctO2 (∆ = 9 ± 5 vs. 6 ± 4%) showed more increase with no difference in ∆SptO2 (∆ = 8 ± 7 vs. 8 ± 8%). Atropine caused higher ∆HR (13 (9 to 19) vs. 10 ± 6 bpm) and ∆CI (0.4 ± 0.4 vs. 0.2 ± 0.3 l min- 1 m- 2) in sufentanil vs. remifentanil-based anaesthesia, with no difference in ∆MAP, ∆SV and ∆SctO2 and ∆SptO2.

CONCLUSION

Induction of anaesthesia with propofol and sufentanil results in improved haemodynamic stability and higher SctO2 compared to propofol and remifentanil in patients having CABG. Administration of atropine might be useful to counteract or prevent the haemodynamic suppression associated with these opioids.

TRIAL REGISTRATION

Clinicaltrials.gov on June 7, 2013 (trial ID: NCT01871935 ).

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.

Pre-administration of remifentanil in target-controlled propofol and remifentanil anesthesia prolongs anesthesia induction in neurosurgical patients: A double-blind randomized controlled trial

BACKGROUND

Pre- and co-administration of remifentanil in target-controlled propofol and remifentanil anesthesia are the most common methods in clinical practice. However, anesthesia induction time by timing remifentanil administration was not identified. Therefore, we investigated the induction time of anesthesia based on type of remifentanil administration in target-controlled anesthesia.

METHODS

A total of 60 patients were randomly assigned to 1 of 2 groups: Pre-administered with remifentanil before propofol infusion (Group R, n = 30) and co-administered with remifentanil with propofol (Group N, n = 30). The primary outcome was total induction time based on the order of remifentanil administration. Secondary outcomes were from start of the propofol infusion time to loss of consciousness (LOC), rocuronium onset time, time to Bispectral index (BIS) 60, and hemodynamic variables.

RESULTS

The mean ± SD of total induction time was 180.5 ± 49.0 s in Group N and 246.3 ± 64.7 s in Group R (mean difference: 65.8 seconds; 95% CI: 35.0-96.5 s, P < .01). Time to BIS 60 and rocuronium onset time were longer in the Group R (P < .01 and P < .01, respectively). The Δheart rate and Δcardiac output values were lower in the Group R (P = .02 and P = .04, respectively). Injection pain was reported by 11 of 28 (39%) in the Group N and in 2 of 28 (7%) in the Group R (difference in proportion: 32%, 95% CI: 10-51%, P = .01).

CONCLUSION

Pre-administration of remifentanil in target-controlled propofol and remifentanil anesthesia prolongs total induction time about 35% compared to co-administration of remifentanil and propofol by decreased CO.

Comparison of Ephedrine vs. Norepinephrine in Treating Anesthesia-Induced Hypotension in Hypertensive Patients: Randomized Double-Blinded Study

Background

Hypotension is a common problem in general anesthesia. Maintaining the mean arterial pressure by choosing a vasopressor with minimal complications is still discussed in various surgeries.

Objectives

The aim of this study is comparison of ephedrine versus norepinephrine in treating anesthesia-induced hypotension in hypertensive patients in spinal surgery in a randomized double-blinded study.

Methods

This randomized, double-blinded study was approved by Iran University of Medical Sciences, operating room of medical center. Data collection was completed between Jan to Dec 2017. Inclusion criteria included age between 20 and 75 years, history of high blood pressure (a patient who has been treated for maximum 5 years with a anti hypertensive medication), and patients under general anesthesia in spinal surgery. The exclusion criteria were based on American Society of Anesthesiologists physical status of 3 or higher, history of arrhythmia, heart valve disease, cerebrovascular disease, kidney failure, beta-blocker use and diabetes, as well as intra operative massive blood loss. After initiation of anesthesia, when the pressure reaches less than 60, the patient entered the protocol and simultaneously administration of 5 mL/kg serum crystalloid and vasopressor. Patients were randomized to the ephedrine group (n = 28) who received 5 mg ephedrine intravenous (i.v.) or norepinephrine Group (n = 28) who received 10 µg (i.v.) bolus norepinephrine at anesthesia-induced hypotension. The administration of 5 mL/kg serum crystalloid and vasopressor was simultaneous. If the mean arterial pressure (MAP) had not reached 60 mmHg, the same dose should be repeated at a maximum of three or more times at five-minute intervals in the ephedrine group and at two minutes intervals in the norepinephrine group. All parameters were collected before and at the end of administration anesthesia drug and during episodes of hypotension. Hemodynamic variables, frequency of hypotension, and total number of vasopressors doses during anesthesia were recorded and analyzed.

Results

The mean number of hypotension times, the number of vasopressors doses in the first hypotension, the total number of doses consumed during the anesthesia, and heart rate at the end of anesthesia were lower in the norepinephrine group (P) respectively. MAP, 5 minutes after the first episode of hypotension and MAP at the end of anesthesia were higher in norepinephrine group.

Conclusions

Norepinephrine is more effective than ephedrine in maintenance of MAP in hypertensive patients undergoing spinal surgery under general anesthesia.