Purpose

During anesthesia, maneuvers which cause the least disturbance of cerebral oxygenation with the greatest decrease in intracranial pressure would be most beneficial to patients with intracranial hypertension. Both head-up tilt (HUT) and hyperventilation are used to decrease brain bulk, and both may be associated with decreases in cerebral oxygenation. In this observational study, our null hypothesis was that the impact of HUT and hyperventilation on cerebral tissue oxygen saturation (SctO₂) and cerebral blood volume (CBV) are comparable.

Methods

Surgical patients without neurological disease were anesthetized with propofol-remifentanil. Before the start of surgery, frequency-domain near-infrared spectroscopy was used to measure SctO₂ and CBV at the supine position, at the 30° head-up and head-down positions, as well as during hypoventilation and hyperventilation.

Results

Thirty-three patients were studied. Both HUT and hyperventilation induced small decreases in SctO₂ [3.5 (2.6)%; P <0.001 and 3.0 (1.8)%; P <0.001, respectively] and in CBV [0.05 (0.07) mL·100 g⁻¹; P <0.001 and 0.06 (0.05) mL·100 g⁻¹; P <0.001, respectively]. There were no differences between HUT to 30° and hyperventilation to an end-tidal carbon dioxide (ETCO₂) of 25 mmHg (from 45 mmHg) in both SctO₂ (P = 0.3) and CBV (P = 0.4).

Discussion

The small but statistically significant decreases in both SctO₂ and CBV caused by HUT and hyperventilation are comparable. There was no correlation between the decreases in SctO₂ and CBV and the decreases in blood pressure and cardiac output during head-up and head-down tilts. However, the decreases in both SctO₂ and CBV correlate with the decreases in ETCO₂ during ventilation adjustment.

Background Gender-affirming pelvic surgery (GAPS) can be associated with significant postoperative pelvic pain. Given the lack of available peripheral nerve blocks to the perineum, intrathecal morphine (ITM) injection could offer a potent analgesic modality for this patient population. No prior studies to date have been performed examining the analgesic effects of intrathecal morphine for these patients. Methods This retrospective case-control study aims to understand the postoperative analgesic effects of intrathecal morphine for these patients with a historical comparison group of patients who did not receive intrathecal morphine. Results Fourteen patients presented for gender-affirming pelvic surgery over an eight-month period at a single institution and were offered intrathecal morphine for postoperative analgesia. Their analgesic results were compared to a similar historical group of 13 patients who were not offered or declined intrathecal morphine. Conclusions Intrathecal morphine injection is a potent analgesic modality for patients presenting for gender-affirming pelvic surgery.

Background

Paravertebral and serratus plane blocks are both used to treat pain following breast surgery. However, it remains unknown if the newer serratus block provides comparable analgesia to the decades-old paravertebral technique.

Methods

Subjects undergoing unilateral or bilateral non-mastectomy breast surgery were randomized to a single-injection serratus or paravertebral block in a subject-masked fashion (ropivacaine 0.5%; 20 mL unilateral; 16 mL/side bilateral). We hypothesized that (1) analgesia would be non-inferior in the recovery room with serratus blocks (measurement: Numeric Rating Scale), and (2) opioid consumption would be non-inferior with serratus blocks in the operating and recovery rooms. In order to claim that serratus blocks are non-inferior to paravertebral blocks, both hypotheses must be at least non-inferior.

Results

Within the recovery room, pain scores for participants with serratus blocks (n=49) had a median (IQR) of 4.0 (0-5.5) vs 0 (0-3.0) for those with paravertebral blocks (n=51): 0.95% CI -3.00 to -0.00; p=0.001. However, the difference in morphine equivalents did not reach statistical significance for superiority with the serratus group consuming 14 mg (10-19) vs 10 mg (10-16) for the paravertebral group: 95% CI -4.50 to 0.00, p=0.123. Since the 95% CI lower limit of -4.5 was less than our prespecified margin of -2.0, we failed to conclude non-inferiority of the serratus block with regard to opioid consumption.

Conclusions

Serratus blocks provided inferior analgesia compared with paravertebral blocks. Without a dramatic improvement in safety profile for serratus blocks, it appears that paravertebral blocks are superior to serratus blocks for postoperative analgesia after non-mastectomy breast surgery.

Trial registration number

NCT03860974.