Reducing the environmental impact of mask inductions in children: A quality improvement report.

BACKGROUND: Inhalational anesthetic agents are potent greenhouse gases with global warming potential that far exceed that of carbon dioxide. Traditionally, pediatric inhalation inductions are achieved with a volatile anesthetic delivered to the patient in oxygen and nitrous oxide at high fresh gas flows. While contemporary volatile anesthetics and anesthesia machines allow for a more environmentally conscious induction, practice has not changed. We aimed to reduce the environmental impact of our inhalation inductions by decreasing the use of nitrous oxide and fresh gas flows. METHODS: Through a series of four plan-do-study-act cycles, the improvement team used content experts to demonstrate the environmental impact of the current inductions and to provide practical ways to reduce this, by focusing on nitrous oxide use and fresh gas flows, with visual reminders introduced at point of delivery. The primary measures were the percentage of inhalation inductions that used nitrous oxide and the maximum fresh gas flows/kg during the induction period. Statistical process control charts were used to measure improvement over time. RESULTS: 33 285 inhalation inductions were included over a 20-month period. nitrous oxide use decreased from 80% to <20% and maximum fresh gas flows/kg decreased from a rate of 0.53 L/min/kg to 0.38 L/min/kg, an overall reduction of 28%. Reduction in fresh gas flows was greatest in the lightest weight groups. Induction times and behaviors remained unchanged over the duration of this project. CONCLUSIONS: Our quality improvement group decreased the environmental impact of inhalation inductions and created cultural change within our department to sustain change and foster the pursuit of future environmental efforts.

Development and validation of a model to calculate anesthetic agent consumption from inspired and end-expired concentrations, minute ventilation, fresh gas flow and dead space ventilation.

Anesthetic agent consumption is often calculated as the product of fresh gas flow (FGF) and vaporizer dial setting (FVAP). Because FVAP of conventional vaporizers is not registered in automated anesthesia records, retrospective agent consumption studies are hampered. The current study examines how FVAP can be retrospectively calculated from the agent's inspired (FIN) and end-expired concentration (FET), FGF, and minute ventilation (MV). Theoretical analysis of agent mass balances in the circle breathing reveals FVAP = [FIN - (dead space fraction * FIN + (1 - dead space fraction) * FET) * (1 - FGF/MV)]/(1-(1 - FGF/MV)). FIN, FET, FGF and MV are routinely monitored, but dead space fraction is unknown. Dead space fraction for sevoflurane, desflurane, and isoflurane was therefore determined empirically from an unpublished data set of 161 patient containing FVAP, FIN, FET, MV and FGF ranging from 0.25 to 8 L/min delivered via an ADU® (GE, Madison, WI, USA). Dead space fraction for each agent was determined empirically by having Excel's solver function calculate the value of dead space fraction that minimized the sum of the squared differences between dialed FVAP and predicted FVAP. With dead space fraction known, the model was then prospectively tested for sevoflurane in O2/air using data collected over the course of two weeks with one FLOW-i (Getinge, Solna, Sweden) and one Zeus workstation (Dräger, Lübeck, Germany). Because both workstations use an electronically controlled vaporizer/injector, the dialed FVAP were available to allow the calculation of median performance error (MDPE) and median absolute performance error (MDAPE). MDPE and MDAP are reported as median and interquartiles. The empirical dead space fraction for isoflurane, sevoflurane, and desflurane were 0.59, 0.49, and 0.66, respectively. For prospective testing, a total of 149.4 h of useful data were collected from 78 patient with the Zeus and Flow-i combined, with FGF ranging from 0.18 to 8 L/min. The model predicted dialed FVAP well, with a MDPE of -1 (-11, 6) % and MDAPE of 8 (4, 17) %. FVAP can be retrospectively calculated from FIN, FET, FGF, and MV plus an agent specific dead space fraction factor with a degree of error that we believe suffices for retrospective sevoflurane consumption analyses. Performance with other agents and N2O awaits further validation.

Need for clarity and context in case reports on kratom use, assessment, and intervention.

This Letter to the Editor is a response to Broyan and colleagues who recently published a Case Report presenting data on 28 patients in the United States who identified kratom as their primary substance of use and who were subsequently induced on buprenorphine/naloxone for a reported diagnosis of kratom use disorder. We applaud the authors for helping to advance the science on kratom and recognize the difficulties in conducting kratom-related clinical assessment and research. However, a number of inconsistences and generalizations were identified in this Case Report, which also lacked some critical context. Importantly, such inconsistencies and generalizations can be observed throughout kratom-specific case reports. We feel this is now an important opportunity to highlight these issues that are present in the Broyan and colleagues Case report but emphasize that they are not unique to it. We do this with the hope that by acknowledging these issues it can help inform editors, clinicians, and researchers who may not be familiar with kratom and, as a result of this unfamiliarity, may inadvertently present findings in a manner that could confuse readers and even misinform clinical researchers and practitioners.

Memsorb™, a novel CO2 removal device part II: in vivo performance with the Zeus IE®.

Memsorb™ (DMF Medical, Halifax, Canada) is a novel device based upon membrane oxygenator technology designed to eliminate CO2 from exhaled gas when using a circle anesthesia circuit. Exhaled gases pass through semipermeable hollow fibers and sweep gas flowing through these fibers creates a diffusion gradient for CO2 removal. In vivo Memsorb™ performance was tested during target-controlled closed-circuit anesthesia (TCCCA) with desflurane in O2/air using a Zeus IE® anesthesia workstation (Dräger, Lübeck, Germany). Clinical care protocols for using this novel device were guided by in vitro performance results from a prior study (submitted simultaneously). After IRB approval, written informed consent was obtained from 10 ASA PS I-III patients undergoing robot-assisted radical prostatectomy. TCCCA targets were 39% inspired O2 concentration (FIO2) and 5.0% end-expired desflurane concentration (FETdes). Minute ventilation (MV) was adjusted to maintain 4.5-6.0% FETCO2. The O2/air (40% O2) sweep flow into the Memsorb™ was manually adjusted in an attempt to keep inspired CO2 concentration (FICO2) ≤ 0.8%. The following data were collected: FIO2, FETdes, FICO2, FETCO2, MV, fresh gas flow (FGF, O2 and air), sweep flow, and cumulative desflurane usage (Vdes). Vdes of the Zeus IE®-Memsorb™ combination was compared with historical Vdes observed in a previous study when soda lime (DrägerSorb 800 +) was used. Results are reported as median and inter-quartiles. A combination of manually adjusting sweep flow (26 [21,27] L/min) and MV sufficed to maintain FICO2 ≤ 0.8% and FETCO2 ≤ 6.0%, except in one patient in whom the target Zeus IE® FGF had to be increased to 0.7 L/min for 6 min. FIO2 and FETdes were maintained close to their targets. Zeus IE® FGF after 5 min was 0 [0,0] mL/min. Average Vdes after 50 min was higher with Memsorb™ (20.3 mL) compared to historical soda lime canister data (12.3 mL). During target-controlled closed-circuit anesthesia in patients undergoing robot-assisted radical prostatectomy, the Memsorb™ maintained FICO2 ≤ 0.8% and FETCO2 ≤ 6.0%, and FIO2 remained close to target. Modest amounts of desflurane were lost with the use of the Memsorb™. The need for adjustments of sweep flow, minute ventilation, and occasionally Zeus IE® FGF indicates that the Memsorb™ system should preferentially be integrated into an automated closed-loop system.

Memsorb™, a novel CO2 removal device part I: in vitro performance with the Zeus IE®.

Soda lime-based CO2 absorbents are safe, but not ideal for reasons of ecology, economy, and dust formation. The Memsorb™ is a novel CO2 removal device that uses cardiopulmonary bypass oxygenator technology instead: a sweep gas passes through semipermeable hollow fibers, adding or removing gas from the circle breathing system. We studied the in vitro performance of a prototype Memsorb™ used with a Zeus IE® anesthesia machine when administering sevoflurane and desflurane in O2/air mixtures. The Zeus IE® equipped with Memsorb™ ventilated a 2L breathing bag with a CO2 inflow port in its tip. CO2 kinetics were studied by using different combinations of CO2 inflow (VCO2), Memsorb™ sweep gas flow, and Zeus IE® fresh gas flow (FGF) and ventilator settings. More specifically, it was determined under what circumstances the inspired CO2 concentration (FICO2) could be kept < 0.5%. O2 kinetics were studied by measuring the inspired O2 concentration (FIO2) resulting from different combinations of Memsorb™ sweep gas flow and O2 concentrations, and Zeus IE® FGFs and O2 concentrations. Memsorb™'s sevoflurane and desflurane waste was determined by measuring their injection rates during target-controlled closed-circuit anesthesia (TCCCA), and were compared to historical controls when using a soda lime absorbent (Draegersorb 800+) under identical conditions. With 160 mL/min VCO2 and 5 L/min minute ventilation (MV), lowering the sweep gas flow at any fixed Zeus IE® FGF increased FICO2 in a non-linear manner. Sweep gas flow adjustments kept FICO2 < 0.5% over the entire Zeus IE® FGF range tested with VCO2 up to 280 mL/min; tidal volume and respiratory rate affected the required sweep gas flow. At 10 L/min MV and low FGF (< 1.5 L/min), even a maximum sweep flow of 43 L/min was unable to keep FICO2 ≤ 0.5%. When the O2 concentration in the Zeus IE® FGF and the Memsorb™ sweep gas flow differed, FIO2 drifted towards the sweep gas O2 concentration, and more so as FGF was lowered; this effect was absent once FGF > minute ventilation. During sevoflurane and desflurane TCCCA, the Zeus IE® FGF remained zero while agent usage per % end-expired agent increased with increasing end-expired target agent concentrations and with a higher target FIO2. Agent waste during target-controlled delivery was higher with Memsorb™ than with the soda lime product, with the difference remaining almost constant over the FGF range studied. With a 5 L/min MV, Memsorb™ successfully removes CO2 with inflow rates up to 240 mL/min if an FICO2 of 0.5% is accepted, but at 10 L/min MV and low FGF (< 1.5 L/min), even a maximum sweep flow of 43 L/min was unable to keep FICO2 ≤ 0.5%. To avoid FIO2 deviating substantially from the O2 concentration in the fresh gas, the O2 concentration in the fresh gas and sweep gas should match. Compared to the use of Ca(OH)2 based CO2 absorbent, inhaled agent waste is increased. The device is most likely to find its use integrated in closed loop systems.

Carbon Dioxide Absorption During Inhalation Anesthesia: A Modern Practice.

CO2 absorbents were introduced into anesthesia practice in 1924 and are essential when using a circle system to minimize waste by reducing fresh gas flow to allow exhaled anesthetic agents to be rebreathed. For many years, absorbent formulations consisted of calcium hydroxide combined with strong bases like sodium and potassium hydroxide. When Sevoflurane and Desflurane were introduced, the potential for toxicity (compound A and CO, respectively) due to the interaction of these agents with absorbents became apparent. Studies demonstrated that strong bases added to calcium hydroxide were the cause of the toxicity, but that by eliminating potassium hydroxide and reducing the concentration of sodium hydroxide to <2%, compound A and CO production is no longer a concern. As a result, CO2 absorbents have been developed that contain little or no sodium hydroxide. These CO2 absorbent formulations can be used safely to minimize anesthetic waste by reducing fresh gas flow to approach closed-circuit conditions. Although absorbent formulations have been improved, practices persist that result in unnecessary waste of both anesthetic agents and absorbents. While CO2 absorbents may seem like a commodity item, differences in CO2 absorbent formulations can translate into significant performance differences, and the choice of absorbent should not be based on unit price alone. A modern practice of inhalation anesthesia utilizing a circle system to greatest effect requires reducing fresh gas flow to approach closed-circuit conditions, thoughtful selection of CO2 absorbent, and changing absorbents based on inspired CO2.

Estimating the Impact of Carbon Dioxide Absorbent Performance Differences on Absorbent Cost During Low-Flow Anesthesia.

BACKGROUND: Reducing fresh gas flow when using a circle anesthesia circuit is the most effective strategy for reducing both inhaled anesthetic vapor cost and waste. As fresh gas flow is reduced, the amount of exhaled gas rebreathed increases, but the utilization of carbon dioxide absorbent increases as well. Reducing fresh gas flow may not make economic sense if the increased cost of absorbent utilization exceeds the reduced cost of anesthetic vapor. The primary objective of this study was to determine the minimum fresh gas flow at which absorbent costs do not exceed vapor savings. Another objective is to provide a qualitative insight into the factors that influence absorbent performance as fresh gas flow is reduced. METHODS: A mathematical model was developed to compare the vapor savings with the cost of carbon dioxide absorbent as a function of fresh gas flow. Parameters of the model include patient size, unit cost of vapor and carbon dioxide absorbent, and absorbent capacity and efficiency. Boundaries for fresh gas flow were based on oxygen consumption or a closed-circuit condition at the low end and minute ventilation to approximate an open-circuit condition at the high end. Carbon dioxide production was estimated from oxygen consumption assuming a respiratory quotient of 0.8. RESULTS: For desflurane, the cost of carbon dioxide absorbent did not exceed vapor savings until fresh gas flow was almost equal to closed-circuit conditions. For sevoflurane, as fresh gas flow is reduced, absorbent costs increase more slowly than vapor costs decrease so that total costs are still minimized for a closed circuit. Due to the low cost of isoflurane, even with the most effective absorbent, the rate of absorbent costs increase more rapidly than vapor savings as fresh gas flow is reduced, so that an open circuit is least expensive. The total cost of vapor and absorbent is still lowest for isoflurane when compared with the other agents. CONCLUSIONS: The relative costs of anesthetic vapor and carbon dioxide absorbent as fresh gas flow is reduced are dependent on choice of anesthetic vapor and performance of the carbon dioxide absorbent. Absorbent performance is determined by the product selected and strategy for replacement. Clinicians can maximize the performance of absorbents by replacing them based on the appearance of inspired carbon dioxide rather than the indicator. Even though absorbent costs exceed vapor savings as fresh gas flow is reduced, isoflurane is still the lowest cost choice for the environmentally sound practice of closed-circuit anesthesia.

Exhaled nitric oxide measurement before pediatric adenotonsillectomy: A feasibility study.

BACKGROUND: Exhaled nitric oxide (eNO) is a known biomarker for the diagnosis and monitoring of bronchial hyperreactivity in adults and children. AIMS: To investigate the potential role of eNO measurement for predicting perioperative respiratory adverse events in children, we sought to determine its feasibility and acceptability before adenotonsillectomy. METHODS: We attempted eNO testing in children, 4-12 years of age, immediately prior to admission for outpatient adenotonsillectomy. We used correlations between eNO levels and postoperative adverse respiratory events to make sample size predictions for future studies that address the predictability of the device. RESULTS: One hundred and three (53%) of 192 children were able to provide an eNO sample. The success rate increased with age from 23% (9%-38%) at age 4 to over 85% (54%-98%) after age 9. Using the eNO normal value (<20 ppb) as a cutoff, an expected sample size to detect a significant difference between children with and without adverse events is 868, assuming that respiratory adverse events occur in 29% of children. CONCLUSIONS: eNO testing on the day of surgery has limited feasibility in children younger than 7 years of age. The most common reason for failure was inadequate physical performance while interacting with the testing device. The role of this respiratory biomarker in the context of perioperative outcomes for pediatric adenotonsillectomy remains unknown and should be further studied with improved technologies.

Ten years of the Helsinki Declaration on patient safety in anaesthesiology: An expert opinion on peri-operative safety aspects.

: Patient safety is an activity to mitigate preventable patient harm that may occur during the delivery of medical care. The European Board of Anaesthesiology (EBA)/European Union of Medical Specialists had previously published safety recommendations on minimal monitoring and postanaesthesia care, but with the growing public and professional interest it was decided to produce a much more encompassing document. The EBA and the European Society of Anaesthesiology (ESA) published a consensus on what needs to be done/achieved for improvement of peri-operative patient safety. During the Euroanaesthesia meeting in Helsinki/Finland in 2010, this vision was presented to anaesthesiologists, patients, industry and others involved in health care as the 'Helsinki Declaration on Patient Safety in Anaesthesiology'. In May/June 2020, ESA and EBA are celebrating the 10th anniversary of the Helsinki Declaration on Patient Safety in Anaesthesiology; a good opportunity to look back and forward evaluating what was achieved in the recent 10 years, and what needs to be done in the upcoming years. The Patient Safety and Quality Committee (PSQC) of ESA invited experts in their fields to contribute, and these experts addressed their topic in different ways; there are classical, narrative reviews, more systematic reviews, political statements, personal opinions and also original data presentation. With this publication we hope to further stimulate implementation of the Helsinki Declaration on Patient Safety in Anaesthesiology, as well as initiating relevant research in the future.

Optimal management of apparatus dead space in the anesthetized infant.

Mechanical ventilation of the anesthetized infant requires careful attention to equipment and ventilator settings to assure optimal gas exchange and minimize the potential for lung injury. Apparatus dead space, defined as dead space resulting from devices placed between the endotracheal tube and the Y-piece of the breathing circuit, is the primary source of dead space controlled by the clinician. Due to the small tidal volumes required by infants and neonates, it is easy to create excessive apparatus dead space resulting in unintended hypercarbia or increased minute ventilation in an effort to achieve a desirable PCO2 . The goal of this review was to evaluate the apparatus that are commonly added to the breathing circuit during anesthesia care, and develop recommendations to guide the clinician in selecting apparatus that are best matched to the clinical goals and the patient's size. We include specific recommendations for apparatus that are best suited for different size pediatric patients, with a particular focus on patients <5 kg.

Optimal ventilation of the anesthetized pediatric patient.

Mechanical ventilation of the pediatric patient is challenging because small changes in delivered volume can be a significant fraction of the intended tidal volume. Anesthesia ventilators have traditionally been poorly suited to delivering small tidal volumes accurately, and pressure-controlled ventilation has become used commonly when caring for pediatric patients. Modern anesthesia ventilators are designed to deliver small volumes accurately to the patient's airway by compensating for the compliance of the breathing system and delivering tidal volume independent of fresh gas flow. These technology advances provide the opportunity to implement a lung-protective ventilation strategy in the operating room based upon control of tidal volume. This review will describe the capabilities of the modern anesthesia ventilator and the current understanding of lung-protective ventilation. An optimal approach to mechanical ventilation for the pediatric patient is described, emphasizing the importance of using bedside monitors to optimize the ventilation strategy for the individual patient.

When does apparatus dead space matter for the pediatric patient?

Physiologic dead space is defined as the volume of the lung where gas exchange does not occur. Apparatus dead space increases dead space volume, causing either increased PaCO2 or the need to increase minute ventilation to maintain normocapnia. Children are especially vulnerable because small increases in apparatus dead space can significantly increase dead space to tidal volume ratio (Vd/Vt). The effect of changes in dead space on arterial CO2 (PaCO2) and required minute ventilation were calculated for patients weighing 2 to 17 kg that corresponds to 0 to 36 months of age. Apparatus volumes for typical devices were obtained from the manufacturer or measured by the volume of water required to fill the device. The relationship between the fraction of alveolar CO2 (FaCO2) and dead space volume (Vd) was derived from the Bohr equation, FaCO2 = VCO2/(RR*(Vt - Vd)), where VCO2 is CO2 production, RR is respiratory rate, and Vt is tidal volume. VCO2 was estimated by using Brody's equation for humans aged up to 36 months, (VCO2 = 5.56*(wt)), where weight is in kilogram. Initial conditions were Vt = 8 mL/kg, Vd/Vt = 0.3, and a RR of 20 breaths per minute. The relationship between PaCO2 and dead space was determined for increasing Vd. Rearranging the Bohr equation, the RR required to maintain PaCO2 of 40 mm·Hg was determined as dead space increased. The apparatus Vd of typical device arrangements ranged from 8 to 55 mL, and these values were used for the dead space values in the model. PaCO2 increased exponentially with increasing apparatus dead space. For smaller patients, the PaCO2 increased more rapidly for small changes in Vd than that in larger patients. Similarly, RR required to maintain PaCO2 of 40 mm·Hg increased exponentially with increasing dead space. Increasing apparatus Vd can lead to exponential increases in PaCO2 and/or RR required to maintain normal PaCO2. The effect on PaCO2 is less as patient weight increases, but these data suggest it can be significant for typical circuit components up to at least 17 kg or aged 36 months.

Addressing the variation of post-surgical inpatient census with computer simulation.

OBJECTIVE: This study describes the development of a Discrete Event Simulation (DES) of a large pediatric perioperative department, and its use to compare the effectiveness of increasing the number of post-surgical inpatient beds vs. implementing a new discharge strategy on the proportion of patients admitted to the surgical unit to recover. MATERIALS AND METHODS: A DES of the system was developed and simulated data were compared with 1 year of inpatient data to establish baseline validity. Ten years of simulated data generated by the baseline simulation (control) was compared to 10 years of simulated data generated by the simulation for the experimental scenarios. Outcome and validation measures include percentage of patients recovering in post-surgical beds vs. "off floor" in medical beds, and daily census of inpatient volumes. RESULTS: The proportion of patients admitted to the surgical inpatient unit rose from 79.0% (95% CI, 77.9-80.1%) to 89.4% (95% CI, 88.7-90.0%) in the discharge strategy scenario, and to 94.2% (95% CI, 93.5-95.0%) in the additional bed scenario. The daily mean number of patients admitted to medical beds fell from 9.3 ± 5.9 (mean ± SD) to 4.9 ± 4.5 in the discharge scenario, and to 2.4 ± 3.2 in the additional bed scenario. DISCUSSION: Every hospital is tasked with placing the right patient in the right bed at the right time. Appropriately validated DES models can provide important insight into system dynamics. No significant variation was found between the baseline simulation and real-world data. This allows us to draw conclusions about the ramifications of changes to system capacity or discharge policy, thus meeting desired system performance measures.

Activity space during treatment with medication for opioid use disorder: Relationships with personality, mood, and drug use.

INTRODUCTION: Activity space in people with substance use disorders (SUDs) has been assessed for theoretical reasons and for detection/prevention of relapse. In this observational study, we relate passively obtained activity space measures to mental states and behaviors relevant to the success of treatment for opioid use disorder. Our long-term goal is to use such data to assess risk in real time and to recognize when SUD patients might benefit from a just-in-time intervention. METHODS: We used GPS data from 238 urban residents in the first 16 weeks of stabilization on medication for opioid use disorder to test preregistered hypotheses about activity space (distance traveled, number of locations, time spent moving, and psychosocial-hazard levels of neighborhoods where participants spent time) in relation to certain static variables (personality, mood propensities) and time-varying treatment-relevant behaviors such as craving and use of opioids and cocaine. RESULTS: The most consistent findings were that 1) mobility decreased over the course of the study; 2) neuroticism was associated with overall lower mobility; 3) trait-like positive mood (averaged from momentary ratings) was associated with higher mobility; 4) participants who used cocaine more frequently had lower mobility; 5) early in treatment, participants spent less time moving (i.e., were more sedentary) on days when they were craving. Some of these findings were in the expected direction (i.e., the ones involving neuroticism and positive mood), and some were opposite to the expected direction (i.e., we expected cocaine use to be associated with higher mobility); others (e.g., changes in mobility over time or in relation to craving) involved nondirectional hypotheses. CONCLUSIONS: Real-time information that patients actively provide is valuable for assessing their current state, but providing this information can be burdensome. The current results indicate that certain static or passively obtained data (personality variables and GPS-derived mobility information) are relevant to time-varying, treatment-relevant mental states and drug-related behavior, and therefore might be useful when incorporated into algorithms for detecting need for intervention in real time. Further research should assess how population-specific these relationships are, and how these passive measures can best be combined with low temporal-density, actively-provided data to obtain valid, reliable assessments with minimal burden.

Ecological Momentary Assessment of Self-Reported Kratom Use, Effects, and Motivations Among US Adults.

Importance: Kratom products, which are sold legally in most of the US, contain alkaloids with opioidergic, adrenergic, and serotonergic activity. Millions of people use kratom to relieve pain, improve mood, or self-manage substance use disorders (SUDs). Kratom use has primarily been examined via surveys, in which recall biases among satisfied users may lead to minimization of transient negative outcomes. Further prospective study of kratom use, such as with ecological momentary assessment (EMA), is needed. Objective: To characterize proximal motivators, effects, and patterns of kratom use and to assess whether use frequency is associated with motivations, effects, past-year criteria for SUD for kratom (KUD), or other substance use. Design, Setting, and Participants: For this prospective cross-sectional study, an intensive longitudinal smartphone-based EMA in which participants' current behaviors and experiences were repeatedly sampled in real time was conducted between July 1 and October 31, 2022. Participants comprised a convenience sample of US adults who used kratom at least 3 days per week for at least 4 weeks at the time of online screening. Criteria for past-year KUD were based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Data analysis was performed between November 2022 and November 2023. Exposure: The exposure was 13 401 kratom-use events across 15 days. Main Outcomes and Measures: A baseline survey covering demographics, health, kratom attitudes and behaviors, use motivations, other substance use, and KUD was administered before EMA. Data for the following EMA entries were then collected: event-contingent entries for kratom use (product, dose, and proximal motivations), follow-up entries (short-term effects and consequences of use events), random-prompt entries (mood), beginning-of-day entries (effects of kratom on sleep), and end-of-day entries (daily subjective descriptions of kratom effects). Bayesian regression was used to estimate means and credible intervals. Results: A total of 357 participants completed the EMA. Their mean (SD) age was 38.0 (11.1) years; more than half were men (198 [55.5%]). Participants reported overall motivators of use on the baseline survey that involved managing psychiatric and SUD problems, but proximal motivators evaluated during the EMA involved situation-specific needs such as increasing energy and productivity and decreasing pain. Acute effects were considered congruent with daily obligations. Use patterns, despite having some distinguishing features, were generally similar in their motivators and effects; participants used kratom predominantly during the daytime and seemed to find use frequencies that suited their needs. Higher use patterns were associated with symptoms of physical dependence (eg, withdrawal or tolerance). Co-used substances included caffeine, nicotine, vitamins, and cannabis. Conclusions and Relevance: Most participants in this study reported using kratom in a seemingly nonproblematic way. When such use appeared problematic, the key element was usually that withdrawal avoidance became a proximal motivator. Longitudinal studies examining changes in kratom use patterns and effects over time are needed.