A marked decrease in heart rate variability associated with junctional rhythm during anesthesia with sevoflurane and fentanyl

Junctional rhythm with severe hypotension following infiltration of lidocaine containing epinephrine during dental surgery

We experienced an unusual case of accelerated junctional rhythm with severe hypotension after infiltration of lidocaine containing epinephrine during dental surgery under general anesthesia. The patient's electrocardiogram exhibited retrograde P-waves following the QRS complex, which could be misinterpreted as ST-segment depression. As a temporary measure, administration of ephedrine restored the patient's blood pressure to normal levels. The importance of this case lies in its demonstration of an unexpected and serious side effect of commonly used epinephrine infiltration. This case also highlights the need for accurate interpretation of the electrocardiogram and comprehensive understanding of best practices for patient management.

Junctional Rhythm Preoperatively and During General Anesthesia for Oral and Maxillofacial Surgery

We report a case of junctional rhythm that occurred both preoperatively and later during a portion of general anesthesia. A 19-year-old woman was scheduled to undergo bilateral sagittal split ramus osteotomy after being diagnosed with a jaw deformity. Preoperative electrocardiography (ECG) revealed a junctional rhythm with a slow heart rate (HR). At 90 minutes after anesthesia induction, local anesthesia with 10 mL of 1% lidocaine and 1:100,000 adrenaline was administered. A junctional rhythm appeared 15 minutes after the local anesthesia. We believe that the atrioventricular nodal pacemaker cells accelerated because of the increased sympathetic activity due to the adrenaline. On the preoperative ECG, the junctional rhythm with slow HR appeared as an escaped beat caused by slowing of the primary pacemaker. Therefore, we think that the preoperative junctional rhythm and the junctional rhythm that appeared during general anesthesia were due to different causes. Understanding the cause of a junctional rhythm could lead to more appropriate treatment. We therefore believe that identifying the cause of the junctional rhythm is important in anesthetic management.

Real-time monitoring of heart rate variability in critically ill patients

PURPOSE

Heart rate variability (HRV) is widely used to evaluate autonomic nervous function; however, real-time monitoring of HRV has rarely been attempted in the intensive care unit (ICU). We report our experience in performing real-time monitoring of HRV in our ICU.

METHODS

We investigated 10 critically ill patients on total ventilatory support. Heart rate variability analysis was performed using the MemCalc system, which is a noninvasive, real-time analysis system. The low-frequency (LF) component of HRV reflects sympathetic and parasympathetic modulation, whereas the high-frequency (HF) component mainly reflects parasympathetic modulation. The LF/HF ratio represents a measure of sympathetic/parasympathetic balance.

RESULTS

The HRV parameters for patients breathing spontaneously after extubation were significantly higher than those for patients on total ventilatory support. These findings suggest that mechanical ventilation under sedation may reduce autonomic nervous function in critically ill patients. In a representative case with septic shock, systolic blood pressure and LF/HF ratio showed a significant increase after intravenous infusion of epinephrine and then the HF component showed a significant increase due to vagal reflex.

CONCLUSIONS

The MemCalc system is practicable for real-time monitoring of HRV in the ICU. Heart rate variability parameters may offer useful information in the management of critically ill patients.

A greater decrease in blood pressure after spinal anaesthesia in patients with low entropy of the RR interval

BACKGROUND

The objective of this study was to determine whether pre-operative heart rate variability (HRV) estimated using the newly developed MemCalc method predicts hypotension after spinal anaesthesia (SA).

METHOD

Fifty-two patients with American Society of Anesthesiologists physical status I or II, aged 38-84 years, scheduled to undergo elective transurethral surgery were investigated in this study. Ultra short-term entropy (UsEn) as a non-linear index of HRV was estimated before and after SA using the MemCalc method. The patients were then assigned to two groups (Group LO and HI) according to pre-operative UsEn. SA was performed by intrathecal injection of 17.5 mg of isobaric bupivacaine via interlumbar spaces L3-4 or L4-5. After SA, the haemodynamic fluctuations were recorded and compared between the two groups.

RESULTS

SA significantly decreased LF/HF (a ratio of the low frequency component of HRV to that of the high frequency component) but did not affect UsEn. The percentage decrease in systolic blood pressure (SBP) after SA was 11.4 (9.9)% in group HI, whereas it was 17.5 (9.8)% in group LO (P < 0.05). Furthermore, the number of patients who developed hypotension was significantly higher in group LO.

CONCLUSION

SA significantly decreased LF/HF without affecting UsEn. Patients with a low UsEn developed a greater decrease in SBP after SA. Furthermore, the incidence of hypotension after SA was higher in patients with a low UsEn.

Changes in a surgical stress index in response to standardized pain stimuli during propofol–remifentanil infusion

BACKGROUND

The surgical stress index (SSI) is based on a sum of the normalized pulse beat interval (PBI) and the pulse wave amplitude (PPGA) time series of the photoplethysmography. As a measure of the nociception-anti-nociception balance in response to a standardized pain stimulus, SSI was compared with EEG changes in state and response entropy (SE and RE), PPGA, and heart rate (HR) during various targeted pseudo-steady-state concentrations of propofol and remifentanil.

METHODS

Forty ASA I patients were allocated to one of the four groups to receive a remifentanil step-up/-down effect-compartment target-controlled infusion (Ce(remi)) of 0, 2, 6, 2, 0 ng ml(-1), or 6, 2, 0, 2, 6 ng ml(-1), and an effect-compartment target-controlled propofol infusion (Ce(prop)) to keep the SE between 30 and 50 or 15 and 30, respectively. At each steady-state Ce(remi), maximum change in SSI, SE, RE, PPGA, and HR after a noxious stimulus was compared with the baseline value. A correlation and prediction probability (P(K)) with Ce(prop) and Ce(remi) was measured.

RESULTS

Static and dynamic values of SSI correlated to Ce(remi) better than SE, RE, HR, and PPGA. SSI was independent of Ce(prop), in contrast to SE and RE. The P(K) for Ce(remi) both before and during a noxious stimulus was better with SSI.

CONCLUSIONS

SSI appeared to be a better measure of nociception-anti-nociception balance than SE, RE, HR, or PPGA.