Bispectral Index Changes Following Boluses of Commonly Used Intravenous Medications During Volatile Anesthesia Identified From Retrospective Data

BACKGROUND

Although patients are commonly monitored for depth of anesthesia, it is unclear to what extent administration of intravenous anesthetic medications may affect calculated bispectral (BIS) index values under general anesthesia.

METHODS

In a retrospective analysis of electronic anesthesia records from an academic medical center, we examined BIS index changes associated with 14 different intravenous medications, as administered in routine practice, during volatile-based anesthesia using a novel screening approach. Discrete-time windows were identified in which only a single drug bolus was administered, and subsequent changes in the BIS index, concentration of volatile anesthetic, and arterial pressure were analyzed. Our primary outcome was change in BIS index, following drug administration. Adjusted 95% confidence intervals were compared to predetermined thresholds for clinical significance. Secondary sensitivity analyses examined the same outcomes, with available data separated according to differences in baseline volatile anesthetic concentrations, doses of the administered medications, and length of time window.

RESULTS

The study cohort was comprised of data from 20,170 distinct cases, 54.7% of patients were men, with a median age of 55. In the primary analysis, ketamine at a median dose of 20 mg was associated with a median (confidence limits) increase in BIS index of 3.8 (2.5-5.0). Midazolam (median dose 2 mg) was associated with a median decrease in BIS index of 3.0 (1.5-4.5). Neither of these drug administrations occurred during time periods associated with changes in volatile anesthetic concentration. Analysis for dexmedetomidine was confounded by concomitant decreases in volatile anesthetic concentration. No other medication analyzed, including propofol and common opioids, was associated with a significant change in BIS index. Secondary analyses revealed that similar BIS index changes occurred when midazolam and ketamine were administered at different volatile anesthetic concentrations and different doses, and these changes persisted 11 to 20 minutes postadministration.

CONCLUSIONS

Modest, but persistent changes in BIS index occurred following doses of ketamine (increase) and midazolam (decrease) during periods of stable volatile anesthetic administration.

Clinical Outcomes and Hospital Utilization Among Patients Undergoing Bariatric Surgery With Telemedicine Preoperative Care

Importance

Bariatric surgery is the mainstay of treatment for medically refractory obesity; however, it is underutilized. Telemedicine affords patient cost and time savings and may increase availability and accessibility of bariatric surgery.

Objective

To determine clinical outcomes and postoperative hospital utilization for patients undergoing bariatric surgery who receive fully remote vs in-person preoperative care.

Design, Setting, and Participants

This cohort study comparing postoperative clinical outcomes and hospital utilization after telemedicine or in-person preoperative surgical evaluation included patients treated at a US academic hospital. Participants underwent laparoscopic Roux-en-Y gastric bypass or laparoscopic sleeve gastrectomy after telemedicine or in-person preoperative surgical evaluation between July 1, 2020, to December 22, 2021, or January 1, 2018, to December 31, 2019, respectively. Follow-up was 60 days from date of surgery.

Exposures

Telemedicine-based preoperative care.

Main Outcomes and Measures

Clinical outcomes, including operating room delay, procedure duration, length of hospital stay (LOS), and major adverse events (MAE), and postoperative hospital resource utilization, including emergency department (ED) visit or hospital readmission within 30 days of the surgical procedure.

Results

A total of 1182 patients were included; patients in the telemedicine group were younger (mean [SD] age, 40.8 [12.5] years vs 43.0 [12.2] years; P = .01) and more likely to be female (230 of 257 [89.5%] vs 766 of 925 [82.8%]; P = .01) compared with the control group. The control group had a higher frequency of comorbidity (887 of 925 [95.9%] vs 208 of 257 [80.9%]; P < .001). The telemedicine group was found to be noninferior to the control group with respect to operating room delay (mean [SD] minutes, 7.8 [25.1]; 95% CI, 5.1-10.5 vs 4.2 [11.1]; 95% CI, 1.0-7.4; P = .002), procedure duration (mean [SD] minutes, 134.4 [52.8]; 95% CI, 130.9-137.8 vs 105.3 [41.5]; 95% CI, 100.2-110.4; P < .001), LOS (mean [SD] days, 1.9 [1.1]; 95% CI, 1.8-1.9 vs 2.1 [1.0]; 95% CI, 1.9-2.2; P < .001), MAE within 30 days (3.8%; 95% CI, 3.0%-5.7% vs 1.6%; 95% CI, 0.4%-3.9%; P = .001), MAE between 31 and 60 days (2.2%; 95% CI, 1.3%-3.3% vs 1.6%; 95% CI, 0.4%-3.9%; P < .001), frequency of ER visits (18.8%; 95% CI, 16.3%-21.4% vs 17.9%; 95% CI, 13.2%-22.6%; P = .03), and hospital readmission (10.1%; 95% CI, 8.1%-12.0% vs 6.6%; 95% CI, 3.9%-10.4%; P = .02).

Conclusions and Relevance

In this cohort study, clinical outcomes in the telemedicine group were not inferior to the control group. This observation suggests that telemedicine can be used safely and effectively for bariatric surgical preoperative care.

Application of autogenous periosteum as a membrane in sinus lifting

AIM

To evaluate the success level of autogenous periosteum in sinus lifting as a barrier membrane which contributes positively to wound healing and is effective in bone formation without the risk of tissue rejection.

MATERIALS AND METHODS

In this study, 32 male New Zealand rabbits were used and were divided into four groups, in which eight rabbits were placed randomly. Sinus lifting with lateral window technique was applied bilaterally to all rabbits. In the first group, the upper face of the graft materials applied was left open. In the second group, the removed bone walls were placed back over the graft materials. In the third group, synthetic membranes were placed over the graft materials. In the fourth group, the autogenous periosteums obtained from tibias of the rabbits were placed over the graft materials. After 6 weeks, the rabbits in all groups were sacrificed, and the operated regions were examined histologically, and stereological assessments were conducted regarding new bone formation, connective tissue, and osteoblasts.

RESULTS

After a 6-week recovery period, synthetic membrane showed the highest success rate regarding new bone formation. Autogenous periosteum, which achieved the second highest success rate regarding new bone formation, was the first in the number of osteoblasts.

CONCLUSION

Autogenous periosteum was considered to have the potential to be an alternative to synthetic membranes.

Impact of Guglielmi detachable coils on outcomes of patients with intracranial aneurysms treated by a multidisciplinary team at a single institution

OBJECT

The goal of this study was to investigate the impact of the introduction of the Guglielmi detachable coil (GDC) therapeutic option on the overall management outcome of intracranial aneurysms. The authors accomplished this by assessing patient morbidity and mortality, inflation-adjusted hospital charges, lengths of stay in the hospital and the intensive care unit (ICU), and treatment efficacy.

METHODS

The authors conducted a retrospective analysis of consecutive cases of intracranial intradural aneurysms managed by a single multidisciplinary neurovascular team at a tertiary care, academic referral center during the 24 months preceding the introduction of the GDC procedure (Group I or pre-GDC era, 77 patients) and during the first 24 months after its introduction (Group II or GDC era, 99 patients). Treatment with GDCs was considered for cases of higher clinical grade or poor surgical risk, or in response to patient preference (27 [27%] of 99 patients in Group II). Host and lesion parameters in our cohort were validated against outcome parameters by using univariate and multivariate analyses. The pre-GDC and GDC subgroups of patients were comparable for major disease severity parameters (patient age, lesion location, clinical grade, and hemorrhage severity). There was no significant difference in clinical outcome at 6 months, infarcts on computerized tomography scanning, or aneurysm obliteration rates before and after introduction of GDC treatment. Decreasing trends in duration of hospital and ICU stay and in inflation-adjusted hospital charges occurred well before and thus were unrelated to the introduction of the GDC therapeutic option.

CONCLUSIONS

The results of this study do not demonstrate any significant impact of integration of the GDC modality on clinical outcome, mortality, morbidity, or effectiveness of treatment. Ongoing improvements in hospital charges and length of hospital stay appeared unrelated to the introduction of the GDC option.

Benefits of supplementing St Thomas' Hospital cardioplegic solution with tetraethylammonium on functional and metabolic recovery of isolated rat hearts

This study was designed to evaluate whether the addition of potassium channel blockers, tetraethylammonium, 4-aminopyridine or glibenclamide, to St Thomas' cardioplegia improved myocardial preservation over that achieved by St Thomas' cardioplegic solution alone. Initially, isolated rat hearts were subjected to 30 min of continuous normothermic hypoxic cardioplegia. Control hearts were arrested with St Thomas' cardioplegia followed by tetraethylammonium, glibenclamide or 4-aminopyridine-enriched cardioplegia. Subsequently, in a second experiment, hearts were subjected to 45 min of normothermic global ischaemia, after 3 min of cardioplegia with either tetraethylammonium-enriched or standard St Thomas' cardioplegia. In both regimens, hearts arrested with tetraethylammonium-enriched St Thomas' cardioplegia showed better recovery of contractile function than controls (P<0.001). Creatine kinase levels were significantly lower in the tetraethylammonium group (P<0.001). 4-Aminopyridine treatment caused similar contractility to that of the control group but raised creatine kinase and lactate dehydrogenase levels (P<0.001). Glibenclamide diminished coronary flow autoregulation, and increased lactate dehydrogenase leakage in reperfusion (P<0.05) with similar contractility to controls. The results of this preliminary in vitro study demonstrate that, in rat heart, St Thomas' cardioplegia enriched with tetraethylammonium improves post-ischaemic contractile function and reduces creatine kinase release. It is concluded that high potassium blocks the membrane at the rapid depolarization phase with rapid sodium influx and tetraethylammonium further prevents repolarization by blocking voltage-dependent potassium channels.

Laser bonding of secondary bronchi with solvent--detergent-treated cryoprecipitate

Management of bronchopleural fistula is a challenging clinical problem. Laser-assisted cryoprecipitate bonding techniques offer a means to fix precisely tissue glues into the fistulae through a bronchoscopic approach. Analogous studies exist using fibrin glue with thrombin. Using a canine model, secondary bronchi were sealed with cryoprecipitate made from solvent/detergent-treated plasma (treated to inactivate membrane-enveloped virus) mixed with indocyanine green (absorption 805 nm). Diode laser energy (emission 808 nm, 7.3 W/cm 2) was applied to the solder until dessication was observed. Leakage pressures (n = 7) ranged between 18 and 86 mmHg with a mean of 46 +/- 24 mmHg. Laser-assisted solder techniques provide a reliably strong seal over leaking bronchial stumps and use of dye enhancement prevents undesired collateral thermal injury to surrounding bronchial tissue. Solvent/detergent plasma, prepared by methods shown to inactivate large quantities of HIV, HBV, and HCV, is an effective source of cryoprecipitate and should allow widespread use of pooled human material in a clinical setting.