Impact of hypotension on cerebral perfusion during general anesthesia induction: A prospective observational study in adults

Comparison of different ratios of propofol-ketamine admixture in rapid-sequence induction of anesthesia for emergency laparotomy: a randomized controlled trial

BACKGROUND

We aimed to compare the hemodynamic effect of two ratios of propofol and ketamine (ketofol), namely 1:1 and 1:3 ratios, in rapid-sequence induction of anesthesia for emergency laparotomy.

METHODS

This randomized controlled study included adult patients undergoing emergency laparotomy under general anesthesia. The patients were randomized to receive either ketofol ratio of 1:1 (n = 37) or ketofol ratio of 1:3 (n = 37). Hypotension (mean arterial pressure < 70 mmHg) was managed by 5-mcg norepinephrine. The primary outcome was total norepinephrine requirements during the postinduction period. Secondary outcomes included the incidence of postinduction hypotension, and the intubation condition (excellent, good, or poor).

RESULTS

Thirty-seven patients in the ketofol-1:1 and 35 patients in the ketofol 1:3 group were analyzed. The total norepinephrine requirement was less in the ketofol-1:1 group than in the ketofol-1:3 group, P-values: 0.043. The incidence of postinduction hypotension was less in the ketofol-1:1 group (4 [12%]) than in ketofol-1:3 group (12 [35%]), P-value 0.022. All the included patients had excellent intubation condition.

CONCLUSION

In patients undergoing emergency laparotomy, the use of ketofol in 1:1 ratio for rapid-sequence induction of anesthesia was associated with less incidence of postinduction hypotension and vasopressor consumption in comparison to the 1:3 ratio with comparable intubation conditions.

CLINICAL TRIAL REGISTRATION

NCT05166330. URL: https://clinicaltrials.gov/ct2/show/NCT05166330 .

A long duration of intraoperative hypotension is associated with postoperative delirium occurrence following thoracic and orthopedic surgery in elderly

BACKGROUND

Postoperative delirium (POD) is a common surgical complication associated with increased morbidity and mortality in elderly. Although the underlying mechanisms remain elusive, perioperative risk factors were reported to be closely related to its development. This study was designed to investigate the association between the duration of intraoperative hypotension and POD incidence following thoracic and orthopedic surgery in elderly.

METHOD

The perioperative data from 605 elderly undergoing thoracic and orthopedic surgery from January 2021 to July 2022 were analyzed. The primary exposure was a cumulative duration of mean arterial pressure (MAP) ≤ 65 mmHg. The primary end-point was the POD incidence assessed with confusion assessment method (CAM) or CAM-ICU for three days after surgery. Restricted cubic spline (RCS) was conducted to examine the continuous relationship between the duration of intraoperative hypotension and POD incidence adjusted with patients' demographics and surgery related factors. Then the duration of intraoperative hypotension was categorized into three groups: no hypotension, short (< 5 mins) or long duration (≥ 5 mins) of hypotension for further analysis.

RESULT

The incidence of POD was 14.7% (89 cases out of 605) within three days after surgery. The duration of hypotension presented a non-linear and "inverted L-shaped" effect on POD development. Compared to no hypotension, long duration (adjusted OR 3.93; 95% CI: 2.07-7.45; P < 0.001) rather than short duration of MAP ≤65 mmHg (adjusted OR 1.18; 95% CI: 0.56-2.50; P = 0.671) was closely related to the POD incidence.

CONCLUSION

Intraoperative hypotension (MAP ≤65 mmHg) for ≥5 mins was associated with an increased incidence of POD after thoracic and orthopedic surgery in elderly.

The effect of burst suppression on cerebral blood flow and autoregulation: a scoping review of the human and animal literature

Background: Burst suppression (BS) is an electroencephalography (EEG) pattern in which there are isoelectric periods interspersed with bursts of cortical activity. Targeting BS through anaesthetic administration is used as a tool in the neuro-intensive care unit but its relationship with cerebral blood flow (CBF) and cerebral autoregulation (CA) is unclear. We performed a systematic scoping review investigating the effect of BS on CBF and CA in animals and humans. Methods: We searched MEDLINE, BIOSIS, EMBASE, SCOPUS and Cochrane library from inception to August 2022. The data that were collected included study population, methods to induce and measure BS, and the effect on CBF and CA. Results: Overall, there were 66 studies that were included in the final results, 41 of which examined animals, 24 of which examined humans, and 1 of which examined both. In almost all the studies, BS was induced using an anaesthetic. In most of the animal and human studies, BS was associated with a decrease in CBF and cerebral metabolism, even if the mean arterial pressure remained constant. The effect on CA during periods of stress (hypercapnia, hypothermia, etc.) was variable. Discussion: BS is associated with a reduction in cerebral metabolic demand and CBF, which may explain its usefulness in patients with brain injury. More evidence is needed to elucidate the connection between BS and CA.

ASNM and ASN joint guidelines for transcranial Doppler ultrasonic monitoring: An update

Today, it seems prudent to reconsider how ultrasound technology can be used for providing intraoperative neurophysiologic monitoring that will result in better patient outcomes and decreased length and cost of hospitalization. An extensive and rapidly growing literature suggests that the essential hemodynamic information provided by transcranial Doppler (TCD) ultrasonography neuromonitoring (TCDNM) would provide effective monitoring modality for improving outcomes after different types of vascular, neurosurgical, orthopedic, cardiovascular, and cardiothoracic surgeries and some endovascular interventional or diagnostic procedures, like cardiac catheterization or cerebral angiography. Understanding, avoiding, and preventing peri- or postoperative complications, including neurological deficits following abovementioned surgeries, endovascular intervention, or diagnostic procedures, represents an area of great public and economic benefit for society, especially considering the aging population. The American Society of Neurophysiologic Monitoring and American Society of Neuroimaging Guidelines Committees formed a joint task force and developed updated guidelines to assist in the use of TCDNM in the surgical and intensive care settings. Specifically, these guidelines define (1) the objectives of TCD monitoring; (2) the responsibilities and behaviors of the neurosonographer during monitoring; (3) instrumentation and acquisition parameters; (4) safety considerations; (5) contemporary rationale for TCDNM; (6) TCDNM perspectives; and (7) major recommendations.

Application of Controlled Hypotension During Surgery for Spinal Metastasis

With advances in tumor treatment, metastasis to bone is increasing, and surgery has become the only choice for most terminal patients. However, spinal surgery has a high risk and is prone to heavy bleeding. Controlled hypotension during surgery has outstanding advantages in reducing intraoperative bleeding and ensuring a clear field of vision, thus avoiding damage to important nerves and vessels. Antihypertensive drugs should be carefully selected after considering the patient's age, different diseases, etc, and a single or combined regimen can be used. Hypotension also inevitably leads to a decrease in perfusion of important organs, so the threshold of hypotension and the maintenance time of hypotension should be strictly limited, and the monitoring of important organs during the operation is particularly important. Information such as blood perfusion, blood oxygen saturation, cardiac output, and neurophysiological conduction potential changes should be obtained in a timely fashion, which will help to reduce the risk of hypotension. In short, when applying controlled hypotension, it is necessary to choose an appropriate threshold and duration, and appropriate monitoring should be conducted during the operation to ensure the safety of the patient.

Association Between Intraoperative Arterial Hypotension and Postoperative Delirium After Noncardiac Surgery: A Retrospective Multicenter Cohort Study

BACKGROUND

It is unclear whether intraoperative arterial hypotension is associated with postoperative delirium. We hypothesized that intraoperative hypotension within a range frequently observed in clinical practice is associated with increased odds of delirium after surgery.

METHODS

Adult noncardiac surgical patients undergoing general anesthesia at 2 academic medical centers between 2005 and 2017 were included in this retrospective cohort study. The primary exposure was intraoperative hypotension, defined as the cumulative duration of an intraoperative mean arterial pressure (MAP) <55 mm Hg, categorized into and short (<15 minutes; median [interquartile range {IQR}], 2 [1-4] minutes) and prolonged (≥15 minutes; median [IQR], 21 [17-31] minutes) durations of intraoperative hypotension. The primary outcome was a new diagnosis of delirium within 30 days after surgery. In secondary analyses, we assessed the association between a MAP decrease of >30% from baseline and postoperative delirium. Multivariable logistic regression adjusted for patient- and procedure-related factors, including demographics, comorbidities, and markers of procedural severity, was used.

RESULTS

Among 316,717 included surgical patients, 2183 (0.7%) were diagnosed with delirium within 30 days after surgery; 41.7% and 2.6% of patients had a MAP <55 mm Hg for a short and a prolonged duration, respectively. A MAP <55 mm Hg was associated with postoperative delirium compared to no hypotension (short duration of MAP <55 mm Hg: adjusted odds ratio [ORadj], 1.22; 95% confidence interval [CI], 1.11-1.33; P < .001 and prolonged duration of MAP <55 mm Hg: ORadj, 1.57; 95% CI, 1.27-1.94; P < .001). Compared to a short duration of a MAP <55 mm Hg, a prolonged duration of a MAP <55 mm Hg was associated with greater odds of postoperative delirium (ORadj, 1.29; 95% CI, 1.05-1.58; P = .016). The association between intraoperative hypotension and postoperative delirium was duration-dependent (ORadj for every 10 cumulative minutes of MAP <55 mm Hg: 1.06; 95% CI, 1.02-1.09; P =.001) and magnified in patients who underwent surgeries of longer duration (P for interaction = .046; MAP <55 mm Hg versus no MAP <55 mm Hg in patients undergoing surgery of >3 hours: ORadj, 1.40; 95% CI, 1.23-1.61; P < .001). A MAP decrease of >30% from baseline was not associated with postoperative delirium compared to no hypotension, also when additionally adjusted for the cumulative duration of a MAP <55 mm Hg (short duration of MAP decrease >30%: ORadj, 1.13; 95% CI, 0.91-1.40; P = .262 and prolonged duration of MAP decrease >30%: ORadj, 1.19; 95% CI, 0.95-1.49; P = .141).

CONCLUSIONS

In patients undergoing noncardiac surgery, a MAP <55 mm Hg was associated with a duration-dependent increase in odds of postoperative delirium. This association was magnified in patients who underwent surgery of long duration.