High Mechanical Power and Driving Pressures are Associated With Postoperative Respiratory Failure Independent From Patients' Respiratory System Mechanics

Considerations for Anesthesia in Older Adults with Cannabis Use

Over the past decade, legislative changes occurred in the USA and the western world that were followed by a substantial increase in reported use of cannabis among the general population. Among patients undergoing anesthesia for surgery or interventional procedures, older patients-often defined as adults over 65 years-are one of the fastest-growing populations. Within this group, the prevalence of cannabis use almost tripled over the past decade. In addition to habitual cannabis use, recommendations for treatment of chronic pain with cannabinoids have become increasingly more common. The clinical relevance of cannabis use in older adults is supported by recent studies linking it to increased anesthetic requirements as well as respiratory, cardiovascular, and psychiatric complications following surgery. Still, evidence remains equivocal, as these associations may largely depend on the type, frequency, and route of cannabis administration, and current research is mostly limited to retrospective cohort studies. Multisystemic effects of cannabis can become especially relevant in patients of advanced age undergoing anesthesia, characterized by physiological and pharmacodynamic alterations as well as a higher risks of drug-to-drug interactions. Best-practice guidelines emphasize the need for detailed, systematic preoperative screening for habits of cannabis use, including the history, type, and frequency, to guide perioperative management in these patients. This review discusses considerations for anesthesia in older patients with habitual cannabis use while highlighting strategies and recommendations to ensure safe and effective anesthesia care.

The association between intraoperative low driving pressure ventilation and perioperative healthcare-associated costs: A retrospective multicenter cohort study

STUDY OBJECTIVE

A low dynamic driving pressure during mechanical ventilation for general anesthesia has been associated with a lower risk of postoperative respiratory complications (PRC), a key driver of healthcare costs. It is, however, unclear whether maintaining low driving pressure is clinically relevant to measure and contain costs. We hypothesized that a lower dynamic driving pressure is associated with lower costs.

DESIGN

Multicenter retrospective cohort study.

SETTING

Two academic healthcare networks in New York and Massachusetts, USA.

PATIENTS

46,715 adult surgical patients undergoing general anesthesia for non-ambulatory (inpatient and same-day admission) surgery between 2016 and 2021.

INTERVENTIONS

The primary exposure was the median intraoperative dynamic driving pressure.

MEASUREMENTS

The primary outcome was direct perioperative healthcare-associated costs, which were matched with data from the Healthcare Cost and Utilization Project-National Inpatient Sample (HCUP-NIS) to report absolute differences in total costs in United States Dollars (US$). We assessed effect modification by patients' baseline risk of PRC (score for prediction of postoperative respiratory complications [SPORC] ≥ 7) and effect mediation by rates of PRC (including post-extubation saturation < 90%, re-intubation or non-invasive ventilation within 7 days) and other major complications.

MAIN RESULTS

The median intraoperative dynamic driving pressure was 17.2cmH2O (IQR 14.0-21.3cmH2O). In adjusted analyses, every 5cmH2O reduction in dynamic driving pressure was associated with a decrease of -0.7% in direct perioperative healthcare-associated costs (95%CI -1.3 to -0.1%; p = 0.020). When a dynamic driving pressure below 15cmH2O was maintained, -US$340 lower total perioperative healthcare-associated costs were observed (95%CI -US$546 to -US$132; p = 0.001). This association was limited to patients at high baseline risk of PRC (n = 4059; -US$1755;97.5%CI -US$2495 to -US$986; p < 0.001), where lower risks of PRC and other major complications mediated 10.7% and 7.2% of this association (p < 0.001 and p = 0.015, respectively).

CONCLUSIONS

Intraoperative mechanical ventilation targeting low dynamic driving pressures could be a relevant measure to reduce perioperative healthcare-associated costs in high-risk patients.

Lung-protective ventilation in the management of congenital diaphragmatic hernia

Prioritizing lung-protective ventilation has produced a clear mortality benefit in neonates with congenital diaphragmatic hernia (CDH). While there is a paucity of CDH-specific evidence to support any particular approach to lung-protective ventilation, a growing body of data in adults is beginning to clarify the mechanisms behind ventilator-induced lung injury and inform safer management of mechanical ventilation in general. This review summarizes the adult data and attempts to relate the findings, conceptually, to the CDH population. Critical lessons from the adult studies are that much of the damage done during conventional mechanical ventilation affects normal lung tissue and that most of this damage occurs at the low-volume and high-volume extremes of the respiratory cycle. Consequently, it is important to prevent atelectasis by using sufficient positive end-expiratory pressure while also avoiding overdistention by scaling tidal volume to the amount of functional lung tissue rather than body weight. Paralysis early in acute respiratory distress syndrome improves outcomes, possibly because consistent respiratory mechanics facilitate avoidance of both atelectasis and overdistention-a mechanism that may also apply to the CDH population. Volume-targeted conventional modes may be advantageous in CDH, but determining optimal tidal volume is challenging. Both high-frequency oscillatory ventilation and high-frequency jet ventilation have been used successfully as 'rescue modes' to avoid extracorporeal membrane oxygenation, and a prospective trial comparing the two high-frequency modalities as the primary ventilation strategy for CDH is underway.

Mechanical power density, spontaneous breathing indexes, and prolonged weaning failure: a prospective cohort study

A prospective observational study comparing mechanical power density (MP normalized to dynamic compliance) with traditional spontaneous breathing indexes (e.g., predicted body weight normalized tidal volume [VT/PBW], rapid shallow breathing index [RSBI], or the integrative weaning index [IWI]) for predicting prolonged weaning failure in 140 tracheotomized patients. We assessed the diagnostic accuracy of these indexes at the start and end of the weaning procedure using ROC curve analysis, expressed as the area under the receiver operating characteristic curve (AUROC). Weaning failure occurred in 41 out of 140 patients (29%), demonstrating significantly higher MP density (6156 cmH2O2/min [4402-7910] vs. 3004 cmH2O2/min [2153-3917], P < 0.01), lower spontaneous VT/PBW (5.8 mL*kg-1 [4.8-6.8] vs. 6.6 mL*kg-1 [5.7-7.9], P < 0.01) higher RSBI (68 min-1*L-1 [44-91] vs. 55 min-1*L-1 [41-76], P < 0.01) and lower IWI (41 L2/cmH2O*%*min*10-3 [25-72] vs. 71 L2/cmH2O*%*min*10-3 [50-106], P < 0.01) and at the end of weaning. MP density was more accurate at predicting weaning failures (AUROC 0.91 [95%CI 0.84-0.95]) than VT/PBW (0.67 [0.58-0.74]), RSBI (0.62 [0.53-0.70]), or IWI (0.73 [0.65-0.80]), and may help clinicians in identifying patients at high risk for long-term ventilator dependency.

Personalized Noninvasive Respiratory Support in the Perioperative Setting: State of the Art and Future Perspectives

Background: Noninvasive respiratory support (NRS), including high-flow nasal oxygen therapy (HFNOT), noninvasive ventilation (NIV) and continuous positive airway pressure (CPAP), are routinely used in the perioperative period. Objectives: This narrative review provides an overview on the perioperative use of NRS. Preoperative, intraoperative, and postoperative respiratory support is discussed, along with potential future areas of research. Results: During induction of anesthesia, in selected patients at high risk of difficult intubation, NIV is associated with improved gas exchange and reduced risk of postoperative respiratory complications. HFNOT demonstrated an improvement in oxygenation. Evidence on the intraoperative use of NRS is limited. Compared with conventional oxygenation, HFNOT is associated with a reduced risk of hypoxemia during procedural sedation, and recent data indicate a possible role for HFNOT for intraoperative apneic oxygenation in specific surgical contexts. After extubation, "preemptive" NIV and HFNOT in unselected cohorts do not affect clinical outcome. Postoperative "curative" NIV in high-risk patients and among those exhibiting signs of respiratory failure can reduce reintubation rate, especially after abdominal surgery. Data on postoperative "curative" HFNOT are limited. Conclusions: There is increasing evidence on the perioperative use of NRS. Use of NRS should be tailored based on the patient's specific characteristics and type of surgery, aimed at a personalized cost-effective approach.

Visualizing the dynamic mechanical power and time burden of mechanical ventilation patients: an analysis of the MIMIC-IV database

BACKGROUND

Limiting driving pressure and mechanical power is associated with reduced mortality risk in both patients with and without acute respiratory distress syndrome. However, it is still poorly understood how the intensity of mechanical ventilation and its corresponding duration impact the risk of mortality.

METHODS

Critically ill patients who received mechanical ventilation were identified from the Medical Information Mart for Intensive Care (MIMIC)-IV database. A visualization method was developed by calculating the odds ratio of survival for all combinations of ventilation duration and intensity to assess the relationship between the intensity and duration of mechanical ventilation and the mortality risk.

RESULTS

A total of 6251 patients were included. The color-coded plot demonstrates the intuitive concept that episodes of higher dynamic mechanical power can only be tolerated for shorter durations. The three fitting contour lines represent 0%, 10%, and 20% increments in the mortality risk, respectively, and exhibit an exponential pattern: higher dynamic mechanical power is associated with an increased mortality risk with shorter exposure durations.

CONCLUSIONS

Cumulative exposure to higher intensities and/or longer duration of mechanical ventilation is associated with worse outcomes. Considering both the intensity and duration of mechanical ventilation may help evaluate patient outcomes and guide adjustments in mechanical ventilation to minimize harmful exposure.