The effect of exogenous epinephrine on the incidence of hypotensive/bradycardic events during shoulder surgery in the sitting position during interscalene block

Local anesthetic volume in ultrasound-guided interscalene block and opioid consumption during shoulder arthroscopic surgery: A retrospective comparative study

Interscalene block (ISB) is commonly performed for regional anesthesia in shoulder surgery. Ultrasound-guided ISB enables visualization of the local anesthetic spread and a reduction in local anesthetic volume. However, little is known about the appropriate local anesthetic dose for surgical anesthesia without sedation or general anesthesia. The purpose of our study was to evaluate the appropriate local anesthetic volume by comparing intraoperative analgesics and hemodynamic changes in ISB in arthroscopic shoulder surgery.Overall, 1007 patients were divided into groups 1, 2, and 3 according to the following volume of local anesthetics: 10-19, 20-29, and 30-40 mL, respectively. The use of intraoperative analgesics and sedatives, and the reduction in intraoperative maximum blood pressure and heart rate were compared through retrospective analysis.Fentanyl was used in 55.6% of patients in group 1, which was significantly higher than in those groups 2 and 3 (22.3% and 30.7%, respectively); furthermore, it was also higher than those in groups 2 and 3 in dose-specific comparisons (P < .05). The percent of the maximum reduction in intraoperative systolic blood pressure and heart rate in group 3 was significantly higher than those in groups 1 and 2. Ephedrine administration was lower in group 2 than that in other groups (P < .05). The incidence of hypotensive bradycardic events was lowest (9.1%) at the local anesthetic volume of 24 mL as revealed by the quadratic regression analysis (R2 = 0.313, P = .003).Decreasing the local anesthetic volume to less than 20 mL for ultrasound-guided ISB as the sole anesthesia increases the opioid consumption during shoulder arthroscopic surgery. Local anesthetics >30 mL or increased opioid consumption with <20 mL of local anesthetics could increase the risk of cardiovascular instability intraoperatively. Our findings indicate that 24 mL of local anesthetic could be used to lower the incidence of hypotensive bradycardic events.

Adverse heart rate responses during beach-chair position for shoulder surgeries - A systematic review and meta-analysis of their incidence, interpretations and associations

Background and Aims

Evaluations of adverse heart rate (HR)-responses and HR-variations during anaesthesia in beach-chair-position (BCP) for shoulder surgeries have not been done earlier. We analysed the incidence, associations, and interpretations of adverse HR-responses in this clinical setting.

Methods

We performed a meta-analysis of trials that reported HR-related data in anaesthetised subjects undergoing elective shoulder surgeries in BCP. Studies included prospective, randomised, quasi-randomised and non-randomised, controlled clinical trials as well as observational cohorts. Literature search was conducted in MEDLINE, EMBASE, CINHAL and the Cochrane Central Register of Controlled Trials of the 21^st century. In the first analysis, we studied the incidence and associations of bradycardia/hypotension-bradycardia episodes (HBE) with respect to the type of anaesthesia and different pharmacological agents. In the second, we evaluated anaesthetic influences, associations and inter-relationships between monitored parameters with respect to HR-behaviours.

Results

Among the trials designed with bradycardia/HBE as a primary end point, the observed incidence of bradycardia was 9.1% and that of HBE, 14.9% and 22.7% [(for Interscalene block (ISB) ± sedation) subjects and general anaesthesia (GA) + ISB, respectively]. There was evidence of higher observed risk of developing adverse HR-responses for GA subjects over ISB (Risk Difference, P < 0.05). Concomitant use of β-agonists did not increase risk of HBEs (P = 0.29, I ²= 11.4%) or with fentanyl (P = 0.45, I ²= 0%) for ISB subjects (subgroup analysis). Fentanyl significantly influenced the HR-drop over time [meta-regression, estimates (standard error), 14.9 (5.4), 9.8 (4.3) and 17 (2.6); P = 0.007, 0.024 and <0.001; for early, mid and delayed periods, respectively] in GA subjects. With respect to number of subjects experiencing cerebral desaturation events (CDEs), total intravenous anaesthesia (TIVA)- propofol had higher risk over inhalational anaesthesia (P = 0.006, I ² = 86.7%). Meta-correlation analysis showed relationships between the HR and rSO₂(regional cerebral oxygen saturation) or SjvO₂(jugular venous oxygen saturation) values (r = 0.608, 95%CI, 0.439 to 0.735, P < 0.001, I ²= 77.4% and r = 0.397, 95%CI, 0.151 to 0.597, P < 0.001, I ²= 64.3%, respectively).

Conclusions

There is not enough evidence to claim the associations of adverse HR-responses with any specific factor. HR-fall is maximal with fentanyl and its variability is associated with changes in rSO₂. Fall in rSO₂ could be the common link triggering adverse HR-responses in BCP.

Retrospective analysis of risk factors of hypotensive bradycardic events during shoulder arthroscopic surgery under interscalene blockade in the sitting position

Background

Hypotensive bradycardic events (HBEs) are a frequent adverse event in patients who underwent shoulder arthroscopic surgery under interscalene block (ISB) in the sitting position. This retrospective study was conducted to investigate the independent risk factors of HBEs in shoulder arthroscopic surgery under ISB in the sitting position.

Methods

A total of 2549 patients who underwent shoulder arthroscopic surgery under ISB and had complete clinical data were included in the study. The 357 patients who developed HBEs were included in the HBEs group, and the remaining 2192 in the non-HBEs group. The potential risk factors for HBEs, such as age, sex, past medical history, anesthetic characteristics, and intraoperative medications were collected and compared between the groups. Statistically significant variables were included in a logistic regression model to further evaluate the independent risk factors for HBEs in shoulder arthroscopic surgery under ISB.

Results

The incidence of HBEs was 14.0% (357/2549). Logistic regression analysis revealed that the intraoperative use of hydralazine (odds ratio [OR] 4.2; 95% confidence interval [CI] 2.9–6.3), propofol (OR 2.1; 95% CI 1.3–3.6), and dexmedetomidine (OR 3.9; 95% CI 1.9–7.8) before HBEs were independent risk factors for HBEs in patients who received shoulder arthroscopic surgery under ISB.

Conclusions

The intraoperative use of antihypertensives such as hydralazine and sedatives such as propofol or dexmedetomidine leads to increased risk of HBEs during shoulder arthroscopic surgery under ISB in the sitting position.

Risk factors associated with hypotensive bradycardic events during open shoulder surgery in the beach chair position

BACKGROUND

Shoulder surgery in the beach chair position frequently causes hypotensive bradycardic events (HBEs), which are potentially associated with an increased risk of cerebral hypoperfusion. Here, we aimed to investigate the incidence and characteristics of symptomatic HBEs that require pharmacological interventions, and to identify specific risk factors associated with symptomatic HBEs.

METHODS

We retrospectively examined the records of all patients aged ≥ 18 years who underwent shoulder arthrotomy in the beach chair position between January 2011 and December 2018 at Samsung Medical Center. For patients who experienced HBEs while in the beach chair position, the minimum heart rate and systolic blood pressure were noted, as was the total dose of ephedrine or atropine.

RESULTS

Symptomatic HBEs occurred in 61.0% of all cases (256/420). Two patients with symptomatic HBEs experienced postoperative neurological complications. Multivariable logistic regression analysis showed that preoperative interscalene brachial plexus block (ISB) and advanced age were risk factors associated with symptomatic HBEs (odds ratio [OR]: 3.240, 95% CI: 2.003, 5.242, P < 0.001; OR: 1.060 for each 1-year increase, 95% CI: 1.044, 1.076, P < 0.001, respectively). Receiver operating curve analysis revealed that a threshold of 62 years of age had a moderate degree of accuracy for predicting symptomatic HBEs (area under curve: 0.764, 95% CI: 0.720, 0.804, P < 0.001).

CONCLUSIONS

Considering the increasing risk of neurocognitive complications with aging, proactive hemodynamic management is needed, especially for elderly patients undergoing shoulder surgery in the beach chair position using ISB.

Epinephrine in irrigation fluid for visual clarity in arthroscopic shoulder surgery: a systematic review and meta-analysis

PURPOSE

To investigate whether epinephrine in irrigation fluid improves visual clarity in arthroscopic shoulder surgery.

METHODS

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) that compared the surgical outcomes of patients who did and did not receive epinephrine during arthroscopic shoulder surgery. We searched the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase for relevant RCTs. We used the Cochrane Collaboration's tool to assess the risk of bias and adopted random-effects model meta-analysis to combine data. We used the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) methodology to evaluate the overall quality of the body of the retrieved evidence. The primary outcome was visual clarity. The secondary outcomes were operative time, amount of irrigation fluid, the need for increased pump pressure, and adverse cardiovascular events.

RESULTS

This study included three RCTs with a total of 238 participants (124 in the epinephrine group and 114 in the non-epinephrine group). The use of epinephrine in irrigation fluid for shoulder arthroscopy achieved better visual clarity (standardized mean difference, 1.01; 95% confidence interval [CI] 0.63 to 1.39; p < 0.0001) and less need for increased pump pressure (risk ratio, 0.40; 95% CI 0.25 to 0.64; p = 0.0001) compared to the non-epinephrine group. No significant differences were noted in operative time (mean difference - 5.08; 95% CI - 14.46 to 4.31; p = 0.29) and amount of irrigation fluid (mean difference - 1.04; 95% CI - 2.38 to 0.39; p = 0.12) between the two groups. No adverse events were recorded in any of the included trials.

CONCLUSIONS

The current evidence shows that the use of epinephrine in arthroscopic shoulder surgery may improve visualization and does not appear to have any major disadvantages.

LEVEL OF EVIDENCE

Level I.

Low-Dosage Adrenaline Induces Transient Marked Decrease of Blood Pressure during Functional Endoscopic Sinus Surgery

Background

Low-dosage adrenaline contained in local anesthetics is commonly used for hemostasis during functional endoscopic sinus surgery (FESS), but often causes significant hemodynamic side effects that might be neglected. A randomized, controlled, prospective clinical trial was designed to find out these effects after local infiltration of different concentrations and/or different dosages of adrenaline during FESS under general anesthesia.

Methods

One hundred eight adult patients were randomized into one of four groups to receive 2 mL of 2% lidocaine and adrenaline 1:200,000 (group I), 4 mL of 1% lidocaine and adrenaline 1:400,000 (group II), 4 mL of 1% lidocaine and adrenaline 1:200,000 (group III), or 4 mL of 1% lidocaine (group IV) for local infiltration, respectively. Heart rate, systolic blood pressure (BP), diastolic BP, and mean arterial pressure were monitored continuously in radial artery.

Results

Significant hemodynamic changes, particularly decrease of BP (p < 0.001) with slightly increased heart rate (p < 0.001) ∼1.5 minutes after local infiltration, were observed in group I, group II, and group III compared with the baseline, but not in group IV. However, no significant hemodynamic changes were observed between group I, group II, and group III at the same time points (p > 0.05).

Conclusions

Local infiltration of low-dosage adrenaline causes temporary significant hemodynamic changes, particularly marked decrease of BP during FESS, and there were no significant hemodynamic changes between adrenaline 1:200,000 and 1:400,000.

Anesthesia and Analgesia in the Patient with an Unstable Shoulder

Introduction:

The patient with an unstable shoulder represents a challenge for the anesthesiologist. Most patients will be young individuals in good health but both shoulder dislocation reduction, a procedure that is usually performed under specific analgesia in an urgent setting, and instability surgery anesthesia and postoperative management present certain peculiarities.

Material and Methods:

For the purpose of the article, 78 references including clinical trials and reviews were included. The review was organized considering the patient that presents an acute shoulder dislocation and the patient with chronic shoulder instability that requires surgery. In both cases the aspects like general or regional anesthesia, surgical positions and postoperative pain management were analyzed.

Conclusion:

The patient with an acutely dislocated shoulder is usually managed in the emergency room. Although reduction without analgesia is often performed in non-medical settings, an appropriate level of analgesia will ease the reduction procedure avoiding further complications. Intravenous analgesia and sedation is considered the gold standard but requires appropriate monitorization and airway control. Intraarticular local analgesic injection is considered also a safe and effective procedure. General anesthesia or nerve blocks can also be considered. The surgical management of the patient with shoulder instability requires a proper anesthetic management. This should start with an exhaustive preoperative evaluation that should be focused in identifying potential respiratory problems that might be complicated by local nerve blocks. Intraoperative management can be challenging, especially for patients operated in beach chair position, for the relationship with problems related to cerebral hypoperfusion, a situation related to hypotension events directly linked to patient positioning. Different nerve blocks will help attaining excellent analgesia both during and after the surgical procedure. An interescalene nerve block should be considered the best technique, but in certain cases, other blocks can be considered.

Liposomal bupivacaine versus indwelling interscalene nerve block for postoperative pain control in shoulder arthroplasty: a prospective randomized controlled trial

BACKGROUND

Pain management strategies following shoulder arthroplasty vary significantly. Liposomal bupivacaine (LB) is an extended-release delivery of a phospholipid bilayer encapsulating bupivacaine that can result in drug delivery up to 72 hours. Prior studies in lower extremity surgery demonstrated efficacy of LB in comparison to a single-shot peripheral nerve block; however, no study has investigated LB in a total shoulder arthroplasty population. Therefore, this study compared LB vs. an indwelling interscalene nerve block (IINB).

METHODS

This is a prospective, randomized study of 83 consecutive shoulder arthroplasty patients; 36 patients received LB and a "bridge" of 30 mL of 0.5% bupivacaine, and 47 patients received an IINB. Postoperative visual analog scale pain levels, opiate consumption measured with oral morphine equivalents, length of hospital stay, and postoperative complications were recorded. Continuous variables were compared using an analysis of variance with significance set at P < .05.

RESULTS

Visual analog scale pain scores were statistically higher in the LB cohort immediately postoperatively in the postanesthesia care unit (7.25 vs. 1.91; P = .000) as well as for the remainder of postoperative day 0 (4.99 vs. 3.20; P = .005) but not for the remainder of admission. Opiate consumption was significantly higher among the LB cohort in the postanesthesia care unit (31.79 vs. 7.47; P = .000), on postoperative day 0 (32.64 vs. 15.04; P = .000), and for the total hospital admission (189.50 vs. 91.70, P = .000). Complication numbers and length of stay were not statistically different.

CONCLUSION

Use of an IINB provides superior pain management in the immediate postoperative setting as demonstrated by decreased narcotic medication consumption and lower subjective pain scores.

Effect of an epinephrine mixture for interscalene block on hemodynamic changes after the beach chair position under general anesthesia: a retrospective study

Background

The beach chair position (BCP) can cause significant hypotension. Epinephrine is used to prolong the duration of local anesthetics; it is also absorbed into blood and can exert systemic effects. This study determined the effects of epinephrine mixed with ropivacaine for an interscalene block (ISB) on hemodynamic changes related to BCP.

Methods

Patient data collected from March 2013 to August 2014 were used retrospectively. We divided the patients into three groups: 1) ISB only, 2) I+G (general anesthesia after ISB without epinephrine), and 3) I+E+G (general anesthesia after ISB with epinephrine). Mean blood pressure (MBP) and heart rate (HR) were measured for 30 minutes at 5-minute intervals.

Results

The study analyzed data from 431 patients. MBP tended to decrease gradually in the groups I+G and I+E+G. There were significant differences in MBP between the groups I+G and I, and between the groups I+G and I+E+G. Group I+E+G showed a significant increase in HR compared with the other two groups.

Conclusions

ISB with an epinephrine mixture did not prevent hypotension caused by the BCP after general anesthesia. HR increased only in response to the epinephrine mixture. A well-planned prospective study is required to compare hemodynamic changes in that context.

An Unusual Case of Asystole Occurring during Deep Brain Stimulation Surgery

Background. Symptomatic bradycardia and hypotension in neurosurgery can produce severe consequences if not managed appropriately. The literature is scarce regarding its occurrence during deep brain stimulation (DBS) surgery. Case Presentation. A 67-year-old female presented for left DBS lead placement for essential tremors. During lead implantation, heart rate and blood pressure dropped rapidly; the patient became unresponsive and asystolic. Chest compressions were initiated and epinephrine was given. Within 30 seconds, the patient became hemodynamically stable and conscious. A head CT demonstrated no acute findings. After deliberation, a decision was made to complete the procedure. Assuming the etiology of the episode was the Bezold-Jarisch reflex (BJR), appropriate accommodations were made. The procedure was completed uneventfully. Conclusion. The episode was consistent with a manifestation of the BJR. The patient had a history of neurocardiogenic syncope and a relatively low-volume state, factors prone to the BJR. Overall, lead implantation can still occur safely if preventive measures are employed.

The Effect of Compression Stockings on Cerebral Desaturation Events in Obese Patients Undergoing Shoulder Arthroscopy in the Beach-Chair Position

PURPOSE

To determine if the use of thigh-high compression stockings could decrease the incidence of cerebral desaturation events (CDEs) in patients with a body mass index (BMI) of 30 kg/m(2) or greater undergoing shoulder arthroscopy in the beach-chair position (BCP).

METHODS

Between December 2013 and May 2014, 23 patients aged 18 years or older with a BMI of 30 kg/m(2) or greater undergoing shoulder arthroscopy in the BCP were monitored intraoperatively using near-infrared spectroscopy while wearing thigh-high compression stockings. Data obtained on these patients were compared with data from a previous cohort at our institution comprising 24 patients with a BMI of 30 kg/m(2) or greater who underwent elective shoulder arthroscopy in the BCP with the same monitoring but without wearing compression stockings. The incidence of CDEs was identified in each group.

RESULTS

The incidence of CDEs in the group with compression stockings was 4% (1 of 23) compared with 18% (7 of 24) in the group without compression stockings (P = .048). There were no statistically significant differences in mean age (53.0 years v 53.3 years, P = .91), mean BMI (34.5 kg/m(2)v 36.2 kg/m(2), P = .21), or various medical comorbidities between the treatment group and control group. There was a significant difference in the operative time between the treatment group (156.6 minutes) and control group (94.1 minutes) (P < .001).

CONCLUSIONS

The use of thigh-high compression stockings may decrease the incidence of CDEs in obese patients undergoing shoulder arthroscopy in the BCP.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Effect of intravenous ondansetron on reducing the incidence of hypotension and bradycardia events during shoulder arthroscopy in sitting position under interscalene brachial plexus block: A prospective randomized trial

Background and Aims:

Sudden, profound hypotension and bradycardia events (HBEs) have been reported in more than 20% of patients undergoing shoulder arthroscopy in the sitting position. The present study was designed to know whether intravenous (IV) ondansetron (selective 5-hydroxy tryptamine 3-antagonist) can help in reducing the HBEs associated with shoulder arthroscopy performed in sitting position under interscalene brachial plexus block (ISBPB).

Methods:

A total of 100 patients (age 20–50 years) undergoing shoulder arthroscopy performed in the sitting position under ISBPB were assigned randomly to one of the two groups: Group C received 10 ml of normal saline and Group T received 4 mg of ondansetron diluted in 10 ml of normal saline` IV. All patients received ISBPB using levobupivacaine 0.5%. Assessment of motor and sensory blockade, pulse rate, systolic blood pressure, respiration, and side effects were noted every 5 min for first 30 min and every 10 min till the end of surgery. HBEs were recorded in both groups.

Results:

IV injection of ondansetron significantly reduces the incidence of HBEs from 11 (22.44% in Group C) to 3 (6.1% in Group T). The duration of analgesia was significantly longer in Group C (8.1 ± 3.3) in comparison with Group T (6.3 ± 4.2 h).

Conclusion:

We conclude that 4 ml of IV ondansetron can significantly reduce the HBEs during shoulder arthroscopy done in the sitting position under ISBPB.

The effect of norepinephrine versus epinephrine in irrigation fluid on the incidence of hypotensive/bradycardic events during arthroscopic rotator cuff repair with interscalene block in the sitting position

PURPOSE

To compare the occurrence rate of hypotensive and bradycardic events (HBEs) during arthroscopic rotator cuff repair performed with interscalene brachial plexus block anesthesia in the sitting position in 2 groups of patients who underwent the procedure with norepinephrine or epinephrine added to the irrigation fluid. The secondary objective was to evaluate the efficacy of norepinephrine in comparison with epinephrine in controlling intraoperative bleeding and maintaining adequate visualization of the arthroscopic field of view during the procedure. We hypothesized that norepinephrine added to the irrigation fluid during shoulder arthroscopy in the sitting position would reduce the occurrence of HBEs, allowing optimal intraoperative bleeding control.

METHODS

One hundred twenty patients underwent an arthroscopic rotator cuff repair performed under peripheral anesthesia and in the beach-chair position. Patients were randomly divided into 2 groups of 60 cases each: Norepinephrine (0.66 mg/L) and epinephrine (0.33 mg/L) were added to irrigation bags in group N and group E, respectively. The primary outcome was the occurrence rate of HBEs during surgery. The secondary outcomes were timing of onset of HBEs, accompanying symptoms, and intraoperative bleeding that impaired arthroscopic visualization. The clarity of the visual field was rated postoperatively by the surgeon using a visual analog scale. Comparison between groups for all baseline variables and outcome measurements was performed with the χ(2) or Fisher exact test, as appropriate, for categorical variables and the Student t test or Mann-Whitney U test, as appropriate, for continuous variables. Significance was set at P < .05.

RESULTS

One patient was excluded from group E because of block failure; therefore 119 patients were finally included in the study. Comparison between groups showed no significant differences in baseline characteristics. The occurrence rate of HBEs was significantly greater in group E (n = 15) than in group N (n = 5) (P = .02). No differences between groups were found in the average time of onset of HBEs, accompanying symptoms, and clarity of the visual field.

CONCLUSIONS

Continuous administration of norepinephrine, 0.66 mg/L, diluted in irrigation fluid during arthroscopic rotator cuff repair with the patient in the beach-chair position reduces the incidence of HBEs and is as effective as epinephrine in controlling intraoperative bleeding and maintaining the visual clarity of the surgical field.

LEVEL OF EVIDENCE

Level I, randomized clinical study.

Continuous interscalene brachial plexus block versus parenteral analgesia for postoperative pain relief after major shoulder surgery

BACKGROUND

Postoperative pain may lead to adverse effects on the body, which might result in an increase in morbidity. Its management therefore poses a unique challenge for the clinician. Major shoulder surgery is associated with severe postoperative pain, and different modalities are available to manage such pain, including opioid and non-opioid analgesics, local anaesthetics infiltrated into and around the shoulder joint and regional anaesthesia. All of these techniques, alone or in combination, have been used to treat the postoperative pain of major shoulder surgery but with varying success.

OBJECTIVES

The objective of this review was to compare the analgesic efficacy of continuous interscalene brachial plexus block (ISBPB) with parenteral opioid analgesia for pain relief after major shoulder surgery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 12), MEDLINE (1950 to December 2012), EMBASE (1980 to December 2012), Web of Science (1954 to December 2012), CINAHL (1982 to December 2012) and bibliographies of published studies.

SELECTION CRITERIA

We included randomized controlled trials assessing the effectiveness of continuous ISBPB compared with different forms of parenteral opioid analgesia in relieving pain in adult participants undergoing elective major shoulder surgery.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted outcome data.

MAIN RESULTS

We included two randomized controlled trials (147 participants). A total of 17 participants were excluded from one trial because of complications related to continuous ISBPB (16) or parenteral opioid analgesia (one). Thus we have information on 130 participants (66 in the continuous ISBPB group and 64 in the parenteral opioid group). The studies were clinically heterogeneous. No meta-analysis was undertaken. However, results of the two included studies showed better pain relief with continuous ISBPB following major shoulder surgery and a lower incidence of complications when interscalene block is performed under ultrasound guidance rather than without it.

AUTHORS' CONCLUSIONS

Because of the small number of studies (two) relevant to the subject and the high risk of bias of the selected studies, no reasonable conclusion can be drawn.

[Clinical relevance of cardiopulmonary reflexes in anesthesiology]

The baroreflex, chemoreflex, pulmonary reflexes, Bezold-Jarisch and Bainbridge reflexes and their interaction with local mechanisms, are a demonstration of the richness of cardiovascular responses that occur in human beings. As well as these, the anesthesiologist must contend with other variables that interact by attenuating or accentuating cardiopulmonary reflexes such as, anesthetic drugs, surgical manipulation, and patient positioning. In the present article we review these reflexes and their clinical relevance in anesthesiology.

Effect of interscalene brachial plexus block on heart rate variability

Background

Interscalene brachial plexus block (ISB) may be followed by cardiovascular instability. Until date, there is no clear picture available about the underlying mechanisms of ISB. In this study, we aimed to determine the changes in heart rate variability (HRV) parameters after ISB and the differences between right- and left-sided ISBs.

Methods

We prospectively studied 24 patients operated for shoulder surgery in sitting position and divided them into two respective groups: R (right-sided block = 14 pts) and L (left-sided block = 10 pts). HRV data were taken before and 30 min after the block. Ropivacaine without ephedrine was used for the ISB through an insulated block needle connected to a nerve stimulator. Statistical analysis implemented chi-square, Student's and t-paired tests. Skewed distributions were analyzed after logarithmic transformation.

Results

All the studied patients had successful blocks. Horner's syndrome signs were observed in 33.3% of the patients (R = 5/14, L = 3/10; [P = 0.769]). There were no significant differences in pre-block HRV between the groups. The application of ISB had differential effect on HRV variables: R-blocks increased QRS and QTc durations and InPNN50, while a statistical decrease was seen in InLF. L-blocks did not show any significant changes. These changes indicate a reduced sympathetic and an increased parasympathetic influence on the heart's autonomic flow after R-block.

Conclusions

Based on the obtained results we conclude that ISB, possibly through extension of block to the ipsilateral stellate ganglion, alters the autonomic outflow to the central circulatory system in a way depending on the block's side.

A cardiovascular collapse occurred in the beach chair position for shoulder arthroscopy under general anesthesia -A case report-

The occurrence of severe hypotension and bradycardia, following placing to the beach chair position from supine during general anesthesia for repair of tendon injury of the rotator cuff of shoulder in a healthy 50 year-old man was described. The Bezold-Jarisch reflex, which is known to inhibit cardiovascular reflex and composed of three kinds of symptoms such as vasodilation, bradycardia and hypotension, has been reported mainly in peripheral nerve block, and may occur during orthostasis, hypovolemia, hemorrhage, supine inferior vena cava compression in pregnancy, interscalene block for shoulder surgery in the sitting position and so on. The bradycardia and hypotension can be more aggravated when causative elements overlaps each other. Anticholinergics and vasopressor were injected intravenously, and position of the patient was changed to the supine position immediately resulting in a normal vital signs dramatically.

Hypotensive bradycardic events during shoulder arthroscopic surgery under interscalene brachial plexus blocks

Sudden, profound hypotensive and bradycardic events (HBEs) have been reported in more than 20% of patients undergoing shoulder arthroscopy in the sitting position. Although HBEs may be associated with the adverse effects of interscalene brachial plexus block (ISBPB) in the sitting position, the underlying mechanisms responsible for HBEs during the course of shoulder surgery are not well understood. The basic mechanisms of HBEs may be associated with the underlying mechanisms responsible for vasovagal syncope, carotid sinus hypersensitivity or orthostatic syncope. In this review, we discussed the possible mechanisms of HBEs during shoulder arthroscopic surgery, in the sitting position, under ISBPB. In particular, we focused on the relationship between HBEs and various types of syncopal reactions, the relationship between HBEs and the Bezold-Jarisch reflex, and the new contributing factors for the occurrence of HBEs, such as stellate ganglion block or the intraoperative administration of intravenous fentanyl.

Documented Intraoperative Hypotension According to the Three Most Common Definitions Does Not Match the Application of Antihypotensive Medication

This observational study investigated which of the three most common definitions of intraoperative hypotension (IOH), reported in a published systematic literature review, were associated best with anaesthetists' administration of antihypo-tensive medication (AHM). IOH and AHM use in anaesthetic procedures in a mixed surgical population ( n = 2350) were also reviewed. The definitions were: arterial systolic blood pressure (SBP) < 100 mmHg or a fall in SBP of > 30% of the preoperative SBP baseline; arterial SBP < 80 mmHg; a fall in SBP of > 20% of the preoperative SBP. Accuracy of predicting AHM using these three definitions was 67%, 54% and 65%, respectively. Prediction by a new fourth definition, using an optimal threshold of minimal SBP falling to < 92 mmHg or by > 24% of preoperative baseline, was 68% accurate. In multivariate logistic analysis, age, volatile versus intravenous anaesthetics, medical history of arterial hypertension and all four definitions of IOH were associated with intraoperative AHM, however IOH was not associated with postoperative in-patient stay. The three original definitions correlated poorly with the anaesthetist's judgement about applying AHM. Anaesthetists make complex decisions regarding the relevance of IOH, considering various perioperative factors in addition to SBP. Age, physical status and duration and type of surgery showed better correlations with postoperative in-patient stay than IOH.

Intravenous fentanyl during shoulder arthroscopic surgery in the sitting position after interscalene block increases the incidence of episodes of bradycardia hypotension

Background

Episodes of bradycardia hypotension (BH) or vasovagal syncope have a reported incidence of 13-29% during arthroscopic shoulder surgery in the sitting position after an interscalene block (ISB). This study was designed to investigate whether intravenous fentanyl during shoulder arthroscopy in the sitting position after ISB would increase or worsen the incidence of BH episodes.

Methods

In this prospective study, 20 minutes after being in a sitting position, 160 patients who underwent ISB were randomized to receive saline (S, n = 40), 50 µg of fentanyl (F-50, n = 40), 100 µg of fentanyl (F-100, n = 40) or 30 mg of ketorolac (K-30, n = 40) randomly. We assessed the incidence of BH episodes during the operation and the degree of maximal reduction (Rmax) of blood pressure (BP) and heart rate (HR).

Results

The incidence of BH episodes was 10%, 15%, 27.5% and 5% in the S, F-50, F-100 and K-30 groups, respectively. Mean Rmax of systolic BP in the F-100 group was significantly decreased as compared to the S group (-20.0 ± 4.5 versus -6.3 ± 1.6%, P = 0.004). Similarly, mean Rmax of diastolic BP in the F-100 group was also significantly decreased (P = 0.008) as compared to the S group.

Conclusions

These results suggest that fentanyl can increase the incidence of BH episodes during shoulder arthroscopic surgery in the sitting position after ISB.

Pathomechanisms and complications related to patient positioning and anesthesia during shoulder arthroscopy

The lateral decubitus and beach-chair positions each offer unique benefits to the shoulder surgeon with respect to visualization, efficiency, and ease during arthroscopic shoulder procedures. The purpose of this article was to comprehensively review the reports and studies documenting independent and dependent complications related to patient positioning and anesthesia during arthroscopic shoulder surgery. The lateral decubitus position has been associated with the potential for peripheral neurapraxia, brachial plexopathy, direct nerve injury, and airway compromise. The beach-chair position has been associated with cervical neurapraxia, pneumothorax, and the potential for end-organ hypoperfusion injuries (when deliberate hypotension is used). Potentially concerning are hypotensive bradycardic events, which may be relatively common in association with the use of epinephrine-containing interscalene anesthetics in beach chair-positioned patients. Irrigant complications (fluid spread, ventricular tachycardia) are avoidable risks not unique to either specific position. Although minor transient anesthetic- and position-related complications (neurapraxia, hypotension) may occur in as many 10% to 30% of patients, major complications such as end-organ damage or permanent impairments are exceedingly rare. Regardless of position, complications are almost uniformly avoidable if surgeon and anesthetist exercise care and prudent attention to position and anesthetic choices. The purpose of this article is to review the potential for position- and anesthesia-related complications and acquaint the shoulder surgeon with the proposed pathophysiologic mechanisms that can lead to them.

Factors contributing to episodes of bradycardia hypotension during shoulder arthroscopic surgery in the sitting position after interscalene block

Background

Arthroscopic shoulder surgery has been performed in the sitting position under interscalene block (ISB). Bradycardia hypotension (BH) episodes have a reported incidence of 13-29% in this setting. We performed a retrospective study to investigate contributing factors to the occurrence of BH episodes.

Methods

According to BH episodes, we divided 63 patients into two groups: BH group (n = 13) and non-BH group (n = 50). Anesthetic records and block data sheets were reviewed for demographic data, intraoperative medications, sites of ISB, use of epinephrine in local anesthetics, degree of sensory blockade, and percent change of heart rate or systolic blood pressure (SBP). Statistical analysis was done using Chi square test and Student's t-test.

Results

There were no significant differences in the use of epinephrine in local anesthetics between the two groups. The location of ISB site was different between the two groups in that there were relatively more right-sided ISBs in the BH group than in the non-BH group (P = 0.048). The degree of sensory blockade was lower, but not significantly, in the C8 and T1 dermatomes of the BH group than in the non-BH group (P = 0.060 and 0.077, respectively). There was a relatively higher incidence of fentanyl supplementation in the BH group than in the non-BH group (P = 0.000).

Conclusions

These results suggest that right ISB and perioperative supplementation of fentanyl due to incomplete block are possible contributing factors to the occurrence of BH episodes in the sitting position during shoulder surgery using ISB.

[Hemodynamic effect of local infiltrative 2% lidocaine adrenaline anesthesia in general balanced anesthesia during middle ear surgery]

Hemodynamic effect of different techniques and type of anesthesia are defined. The volume of reduced hemorrhage in surgical field is debatable, without any definite conclusion. The objective of the study is to investigate the effects of local infiltrative anesthesia with adrenaline during general balanced anesthesia and nitroglicerol on blood presure and hemorrhage reduction in middle ear operations. Prospective, randomized study included 58 adult patients planned for the otorhinolaryngological surgery. Studied group of patient (n 30) planned for middle ear operations. Befora incision surgeon was administered local infiltrative anesthesia using 2% lidocaine with adrenaline (1:200,000) The controls group (n 28), planned for other surgery had no local infiltrative anesthesia with adrenaline. Hemodinamic parameters were monitored before surgical incision and 30 minutes after that. Surgeon's verbal reply on hemorrhage reduction during surgery was recorded. Statistical analysis of parametric data was carried out by Mann-Whitney sum test. Blood pressure and heart rate was not different between the two groups. But, intraoperatively, the study showed lowering of sistolic and diastolic blood pressure. This mode of treatment and surgeon's verbal reply confirmed that local infiltrative anesthesia with adrenaline under balanced anesthesia had no effect on hemorrhage reductionin surgical field.

Crisis management during anaesthesia: bradycardia

BACKGROUND

Bradycardia in association with anaesthesia may have many potential causes and associated conditions, some rare and/or obscure. A prompt appropriate response is important as some homeostatic mechanisms may be impaired under anaesthesia.

OBJECTIVES

To examine the role of a previously described core algorithm "COVER ABCD-A SWIFT CHECK", supplemented by a specific sub-algorithm for bradycardia, in the management of bradycardia occurring in association with anaesthesia.

METHODS

The potential performance of this structured approach for each of the relevant incidents among the first 4000 reported to the Australian Incident Monitoring Study (AIMS) was compared with the actual management as reported by the anaesthetists involved.

RESULTS

From the first 4000 incidents reported to AIMS, 265 reports which described bradycardia during anaesthesia were extracted and studied. Bradycardia was associated with hypotension in 51% of cases, cardiac arrest in 25% of cases and hypertension in one case. In 22% of reports apparent desaturation or an abnormality of ventilation was described. Bradycardia was caused by drug events (28%), airway related events (16%), autonomic reflexes (14%), and regional anaesthesia (9%). Airway and drug events caused 75% of cases involving children. It was considered that, correctly applied, the core algorithm COVER would have diagnosed 53 cases (20%) and led to corrective management in 45 (85%) of these; this included an important subset of airway and ventilation problems. Completion of COVER ABCD-A SWIFT CHECK followed by the specific sub-algorithm for bradycardia would have resulted in diagnosis and appropriate management in all but two cases. It would have led to earlier recognition of the problem and/or better management in 11 cases (4%) when compared with the actual management described in the reports.

CONCLUSION

Steps should be taken to manage bradycardia whilst associated conditions are managed concurrently. Analysis of cardiac rhythm should not be pursued to the exclusion of supportive therapy. The use of a structured approach in the management of bradycardia associated with anaesthesia is likely to improve management in the small percentage of cases in which the diagnosis of the cause may be missed or delayed.

Local anesthesia for functional endoscopic sinus surgery employing small volumes of epinephrine-containing solutions of lidocaine produces profound hypotension

BACKGROUND

Local anesthetic containing epinephrine is commonly used in many operations for the main purpose of hemostasis. A randomized, controlled, prospective clinical trial was designed to find out hemodynamic changes after local infiltration of different concentrations and/or different dosages of epinephrine during functional endoscopic sinus surgery (FESS) under general anesthesia.

METHODS

One hundred and eight adult patients undergoing elective FESS under general anesthesia were randomly allocated into four groups. Group I received 2% lidocaine 2 ml with epinephrine (5 microg/ml); group II received 1% lidocaine 4 ml with epinephrine (2.5 microg/ml); group III received 1% lidocaine 4 ml with epinephrine (5 microg/ml); and group IV received 1% lidocaine 4 ml for local infiltration. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were monitored continuously in the radial artery and recorded in 6 min: before infiltration (baseline), 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, and 6 min after local infiltration. The lowest blood pressure (BP) in this period was also recorded.

RESULTS

Significant hemodynamic changes, particularly a decrease in BP (P < 0.001) with a slight increase in HR (P < 0.001) at approximately 1.5 min and an increase in SBP at approximately 3 min (P < 0.01) after local infiltration, were observed in group I, group II and group III compared with the baseline, but not in group IV. No significant hemodynamic differences were observed between group I, group II and group III at the same time points (P > 0.05).

CONCLUSION

Local infiltration of low-dose epinephrine causes temporary significant hemodynamic changes particularly a marked decrease in BP during FESS under general anesthesia.

Sedation with target-controlled propofol infusion during shoulder surgery under interscalene brachial plexus block in the sitting position

BACKGROUND AND OBJECTIVE

The aim of this study was to assess target-controlled propofol infusion as a technique of sedation for shoulder surgery under interscalene brachial plexus block in the sitting position and to evaluate the effect of sedation on hypotensive/bradycardic events during this procedure.

METHODS

One hundred and forty patients undergoing elective shoulder surgery in the sitting position under interscalene brachial plexus block (with 30 mL of ropivacaine 0.75%) were prospectively enrolled. All patients were premedicated with hydroxyzine 1 mg kg(-1), none received beta-blockers. No patients were given atropine except for the patients who experienced a vasovagal event either during the block procedure or intravenous catheter placement. The target-controlled propofol infusion was started immediately after positioning the patient on the operating table. The initial target concentration was 1 microg mL(-1). The infusion rate was adjusted every 15 min by increasing or decreasing the target concentration by 0.2 microg mL(-1) steps to maintain the patient rousable to verbal commands (score of 3 on Wilson sedation scale). The following parameters were assessed: minimal, maximal, optimal target concentration, respiratory and haemodynamic parameters, total propofol dose, additional alfentanil needs, occurrence of hypotensive/bradycardic events, complications. Results are mean +/- SD. Statistical analysis used t-test and chi2-tests.

RESULTS

The optimal propofol target concentration was 0.8 mug mL(-1). No respiratory complications or conversion to general anaesthesia was reported. Two patients experienced transient and inconsequential intraoperative agitation. The incidence of hypotensive/bradycardic events during the procedure was 5.7% (eight patients).

CONCLUSION

Target-controlled propofol infusion (0.8-0.9 microg mL(-1)) following hydroxyzine premedication is a safe and effective technique for sedation when combined with interscalene brachial plexus block during shoulder surgery in the sitting position.

Marked Hypotension Induced by Adrenaline Contained in Local Anesthetic

OBJECTIVES

Local anesthetics containing adrenaline, which often cause cardiovascular side effects, are routinely used in functional endoscopic sinus surgery (FESS) for the main purpose of hemostasis. The controversies concerning hemodynamic effects of adrenaline in local infiltration are widely discussed, but there is no definite conclusion. A prospective, randomized, double-blinded study was carried out to discover the hemodynamic effects after local infiltration of 1:200,000 adrenaline contained in 2% lidocaine under general anesthesia.

STUDY DESIGN

Seventy-six adult patients undergoing FESS during general anesthesia were allocated randomly into three groups. Group I patients (n = 26) received 2% lidocaine 2 mL with adrenaline (1:200,000), group II patients (n = 25) received saline 2 mL with adrenaline (1:200,000), and group III patients (control group, n = 25) received saline 2 mL without adrenaline for local infiltration. Electrocardiogram (ECG) and heart rate (HR) were monitored simultaneously; systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial blood pressure (MAP) were directly measured in radial artery continuously after local infiltration.

METHODS

SBP, DBP, MAP, and HR were recorded at 10 time points: before infiltration (baseline), 0.5 minutes, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minute, and 5 minutes after infiltration.

RESULTS

Significant hemodynamic changes, particularly hypotension (P < .01), after local infiltration were observed in group I and group II compared with the baseline, but not in group III. However, there were no significant hemodynamic changes between group I and group II at the same time points (P > .05). The significant hemodynamic changes lasted no longer than 4 minutes.

CONCLUSIONS

Lidocaine (2%) or saline with adrenaline (1:200,000) does cause temporary hypotension and other hemodynamic changes during general anesthesia, which last no longer than 4 minutes. The causative mechanism is caused by the effect of adrenaline. This is a preliminary study.

Lower body negative pressure as a model to study progression to acute hemorrhagic shock in humans

Hemorrhage is a leading cause of death in both civilian and battlefield trauma. Survival rates increase when victims requiring immediate intervention are correctly identified in a mass-casualty situation, but methods of prioritizing casualties based on current triage algorithms are severely limited. Development of effective procedures to predict the magnitude of hemorrhage and the likelihood for progression to hemorrhagic shock must necessarily be based on carefully controlled human experimentation, but controlled study of severe hemorrhage in humans is not possible. It may be possible to simulate hemorrhage, as many of the physiological compensations to acute hemorrhage can be mimicked in the laboratory by applying negative pressure to the lower extremities. Lower body negative pressure (LBNP) sequesters blood from the thorax into dependent regions of the pelvis and legs, effectively decreasing central blood volume in a similar fashion as acute hemorrhage. In this review, we compare physiological responses to hemorrhage and LBNP with particular emphasis on cardiovascular compensations that both share in common. Through evaluation of animal and human data, we present evidence that supports the hypothesis that LBNP, and resulting volume sequestration, is an effective technique to study physiological responses and mechanisms associated with acute hemorrhage in humans. Such experiments could lead to clinical algorithms that identify bleeding victims who will likely progress to hemorrhagic shock and require lifesaving intervention(s).