Suggested Work Guidelines,Based on Operating Room Data,for Departments with a Breast Milk Pumping Supervising Anesthesiologist

Abstract

Objective:

Coordinating breast milk pumping sessions is challenging for lactating anesthesiologists who supervise multiple simultaneous anesthetics. We quantify the minimum percentages of adjacent operating rooms (ORs) for which there could reliably (≥95%) be at least 30 minutes during the surgical time when the anesthesiologist covering three anesthetics could have her rooms covered by another anesthesiologist.

Methods:

The historical cohort study was from a large U.S. teaching hospital. We calculated the 5% lower prediction bounds of surgical times from 3 years of historical data, and then applied them to surgical start times from adjacent ORs during the next 1 year.

Results:

For >2/3rd of cases, an anesthesiologist supervising three ORs would lack a reliable 30-minute period of overlapping surgical times, and an even smaller chance per case at the ambulatory surgery center, 10% (9–11%). For approximately 42% (41–43%) of sufficiently long individual cases, there was absence of a 30-minute period during which both of the two adjacent ORs' cases were suitable for the anesthesiologist to receive a break (p < 0.0001 compared with one-third).

Conclusions:

Even when making assumptions that were deliberately unrealistic (e.g., anesthesiologists' responsibilities are only for ongoing OR cases), there is no practical mechanism for an anesthesiologist supervising three ORs to start cases, be relieved for a breast milk pumping session, and then return in time for the end of the anesthetics (e.g., tracheal extubation). Departments with anesthesiologists who are breastfeeding should consider having options for temporary clinical assignments, commensurate with training and experience, that do not require supervising >2 ORs.

Introduction

Among physician mothers, barriers to breastfeeding include lack of time to breastfeed or express breast milk, unpredictable schedules, and inflexible schedules.¹ Physician mothers have initial rates of breastfeeding their newborns surpassing those of the general population, but these rates are below the population average at 1 year postdelivery.² The large majority (87% [868/999]) of physicians' childbirths are after residency and fellowship training.³ Among physician mothers who are U.S. anesthesiologists, survey respondents report lacking adequate facilities or time to express breast milk for 55% (57/104) of pregnancies.⁴ Surveyed anesthesia program directors in New Zealand report significantly less implementation than the perceived importance of “family-friendly” workplace practices, including designated time for breast milk pumping.⁵

Most U.S. anesthesiologists' practices involve clinical supervision of anesthesia residents or nurse anesthetists (i.e., simultaneous coverage of multiple operating rooms [ORs]).ⁱ^,6–10 We recently examined the percentage of surgical cases that reliably (≥95%) had at least 30 minutes during the interval from 15 minutes after surgical incision, or its equivalent, until the procedure(s) has been completed (e.g., dressing on the patient).^11–13 Anesthesiologists who are breastfeeding may have considerably less opportunity to express their breast milk than anesthesia residents or nurse anesthetists assigned to individual ORs.¹³ We hypothesized and tested that even when a single OR would have a reliable interval for breast milk pumping sessions (i.e., an anesthesia resident or nurse anesthetist who is lactating could be relieved,¹³ often (during >1/3rd of such sufficiently long cases), an anesthesiologist supervising three ORs would lack a reliable 30-minute period because one or the other of the adjacent ORs would not be in a portion of the surgery allowing a 30-minute break.

Methods

The University of Iowa Institutional Review Board determined that this project does not meet the regulatory definition of human subjects research because the activity is limited to the analysis of deidentified data provided for routine administrative purposes.

We used the same 4 years of data from a large teaching hospital as in our study of individual cases.¹³ The historical period to estimate surgical times was 3 years:¹⁴ October 2016 through September 2019 with 95,146 cases.¹³ Comparison was made with the following year: October 2019 through September 2020, the contemporaneous period, with 30,987 cases.¹³ For each of those cases, the primary surgical Health care Common Procedure Coding System code was identified.¹⁵ Demographic data of the historical and contemporaneous periods are shown in Table 1 of our recent article.¹³ We considered surgical time to be the period from the documented surgery or procedure start time, most typically incision, to the surgery or procedure end time, most typically applying the dressing on the patient.¹³

Table 1.

Periods with at Least Thirty Minutes from Fifteen Minutes After the Start of Surgery, But Before the End of the Procedure

	All cases combined	Ambulatory surgery center	Children's hospital	Adult surgical suite	Adult surgical suite elective cases
N of column, single cases' 5% lower bounds	30,357	7,987	4,872	17,498	13,411
Single cases reliably ≥30 minutes from (surgery start +15 minutes)	11,932	1,439	1,009	9,484	8,012
%, Denominator is row 1	39%^a	18%^b	21%	54%	60%^c
Pairs of adjacent cases best chance reliably ≥30 minutes overlap	11,271	1,322	929	9,020	7,589
%, Denominator is row 1	37%	17%	19%	52%	57%
Lower 99% CI	36%	16%	18%	51%	56%
Upper 99% CI	38%	18%	21%	52%	58%
Pairs of adjacent cases least chance reliably ≥30 minutes overlap	7,795	835	637	6,323	5,099
%, Denominator is row 1	26%	10%	13%	36%	38%
Lower 99% CI	25%	10%	12%	35%	37%
Upper 99% CI	26%	11%	14%	37%	39%
Triplets of adjacent cases reliably ≥30 minutes overlap	6,928	821	618	5,489	4,296
%, Denominator is row 1	23%	10% ^a	13%	31%	32% ^b
Lower 99% CI	22%	9%	12%	30%	31%
Upper 99% CI	23%	11%	14%	32%	33%
Two-sided p-value making comparison with one-third	<0.0001	<0.0001	<0.0001	<0.0001	0.0014
Single cases, but not triplets reliably with ≥30 minutes	6,928	821	618	5,489	4,296
%, Denominator is row 2	42% ^c	43%	39%	42%	46%
Upper 99% CI	41%	40%	35%	41%	45%
Lower 99% CI	43%	46%	43%	43%	48%
Two-sided p-value making comparison with one-third	<0.0001	<0.0001	0.0003	<0.0001	<0.0001

The first three rows are from Table 3 of our article of single cases.¹³ Those rows are used as denominators for the new analyses. Values in bold are those listed in the “Results” section. The quoted numbers are, in sequence, those of footnote “a” (second sentence of first paragraph), footnote “b” (third sentence of first paragraph), and footnote “c” (second sentence of second paragraph). The fractions are reported without decimal places because the numerators and denominators are given in the table and can be recalculated by readers, as desired.

The “ambulatory surgery center,” “Children's hospital,” and “adult surgical suite” are surgical suites located in three connected, but separate buildings. Elective cases were scheduled two or more days before the date of surgery.

CI, confidence interval.

A prediction bound for a single future observation is a value that will, with a specified degree of confidence, be exceeded by the next randomly selected observation from a population.¹⁶ A 5% lower prediction bound for a given case provides a 5.0% risk of the surgical time being too brief for a breast milk pumping session when an anesthesia resident or nurse anesthetist is given a break and will return before waking the patient up from general anesthesia.¹³ Equivalently, there would be a 95% degree of confidence that the pumping session could be accommodated.¹³ Prediction bounds were used because, while overall, 72.2% of the cases during our contemporaneous period had surgical times ≥45 minutes, 39.3% of the individual cases were sufficiently long that each future case individually had a reliable (≥95%) chance of lasting at least 45 minutes.¹³ For each primary surgical procedure, the historical data provided a sample size, sample mean of logarithms of surgical times, and sample standard deviation of the logarithms of surgical times.^13,16 For procedures with more than 99 previous cases, we limited use to the most recent 99 cases.^13,17–19 The 5.0% lower prediction bound was calculated in the log-scale using the Student's t-distribution.^13,16 Then, the exponential was taken of the result^13,16 to convert the value into units of hours. The observed incidence achieved by our 5% lower prediction bounds was 4.86% (99% confidence interval 4.55–5.19).¹³

We considered the start of the available time for a breast milk pumping session to be 15 minutes after the start of surgery (i.e., allowing for time to finish placing any invasive lines, complete positioning involving potential risk to the patient, ensure appropriate anesthetic dose after incision and resolve hemodynamic issues, and make a brief report to the anesthesiologist covering the ORs during the break). The end of the time available for breast milk pumping session was considered the time of the start of surgery plus the 5% lower prediction bound minus the 15 minutes at the start of surgery, unless the case finished sooner, in which event, it was when the case finished. When the 5% lower prediction bound was <15 minutes, the case had no suitable period.

The sequentially numbered ORs were treated as having cyclic adjacency (e.g., for the 36 OR adult surgical suite, room 1 was paired with rooms 36 and 2, room 2 was paired with rooms 1 and 3, room 3 was paired with rooms 2 and 4, …, and room 36 was paired with rooms 35 and 1). For each of the two adjacent rooms, the maximum overlapping period was calculated. For example, a room had an 81-minute 5% lower prediction bound, surgery starting 8:32 AM, and procedure ending 12:26 PM. The available period for a breast milk pumping session during the case was considered from 8:47 AM to 9:53 AM, where 8:47 AM = 8:32 AM +15 minutes, and 9:53 AM = 8:32 AM +81 minutes. The period from 8:47 AM to 9:53 AM is 66 minutes. The room numbered one less had corresponding time from 8:46 AM to 9:21 AM. The room numbered one greater had corresponding time from 8:56 AM to 10:02 AM. Therefore, the overlapping periods were 8:47 AM to 9:21 AM and from 8:56 AM to 9:53 AM, respectively. These were 57- and 34-minute overlapping periods, respectively. Referring to Table 1, “Pairs of adjacent cases best chance reliably ≥30 minutes overlap” used the 57-minute period. The “pairs of adjacent cases least chance reliably ≥30 minutes overlap” used the 34-minute period. When there was no case in the adjacent room during the period suitable for a breast milk pumping session, that was treated as the best chance because the anesthesiologist was considered having only one ongoing case. Our doing this deliberately biased our results toward overestimating periods when supervising anesthesiologists could have a breast milk pumping session, analogous to our consideration of only OR cases compared with activities outside ORs (e.g., in the postanesthesia care unit).^20–24

Our inferential analyses were for an anesthesiologist with three ongoing cases, “triplets of adjacent cases reliably ≥30-minute overlap.” From the preceding example, the three rooms had overlapping periods from 8:56 AM to 9:21 AM, a 25-minute interval. Exact 99% two-sided confidence intervals for the percentages of pairs and triplets of cases (Table 1) were calculated using the conservative Clopper-Pearson method. The p-values are exact, calculated using the binomial method. The work was done using Microsoft Office 365 Version 2002 Excel (Redmond, WA).

Results

For the large majority of cases (>2/3rd), an anesthesiologist supervising three ORs would lack a reliable (≥95%) 30-minute period of overlapping surgical times for a breast milk pumping session (Table 1). An anesthesiologist working at the ambulatory surgery center might have only a 10% chance per case (9–11%) of having sufficient time to reliably complete a 30-minute breast milk pumping session. The anesthesiologist caring for adult patients undergoing elective inpatient surgery may have a 32% chance (31–33%).

Although single cases may be sufficiently long for a breast milk pumping session by the in-room anesthesia provider, that was much less so when considering the anesthesiologist clinically supervising three ORs. For approximately 42% of such sufficiently long individual cases (99% confidence interval 41–43%), there was absence of a continuous 30-minute period during which one or both adjacent rooms' cases also was suitable (Table 1). The decreases in suitable cases were at least one-third (p < 0.0001 testing our Hypothesis). The percentage decreases from an anesthesiologist supervising multiple ORs were homogeneous among surgical suites (Table 1, last four rows).

Discussion

We previously showed that anesthesia providers who are breastfeeding their children and assigned to individual rooms need to be assigned to ORs with long-duration cases to reliably have sufficient time for a breast milk pumping session during the case.¹³ Our current work shows that anesthesiologists have an approximately 42% smaller chance of time for breast milk pumping sessions. Furthermore, this percentage underestimates the actual decline because we limited consideration to cases overlapping among ORs (see below). In addition, that calculation of the opportunities for anesthesiologists who are breastfeeding their child made the deliberately unrealistic assumption that others would also cover their responsibilities outside the ORs. When supervising anesthesia residents and nurse anesthetists, a substantial portion of anesthesiologists' activities is for subsequent and completed anesthetics.^20–24 Quantitatively, approximately half of pages to anesthesiologists supervising ORs are from outside the ORs (e.g., preoperative holding area).²⁰ Most emergency pages are from outside the ORs (e.g., bradyarrhythmia during intravenous line placement or respiratory event in the postanesthesia care unit).^20,22 Most (>50%) episodes of hypoxemia in the phase I postanesthesia care unit occur at least 30 minutes after patient admission (p < 0.0001) (i.e., after the anesthesia provider has left the patient).²¹ OR control desks at hospitals average ≥1 inpatient cancelation or add-on case scheduled per hour during regular workdays.²³ Finally, when preoperative evaluations are completed on the day of surgery, turnover times are increased (mean 7.5 minutes) unless completed before the previous case in the OR is complete.²⁴ Thus, these previous studies^20–24 strengthen the conclusion that there are significantly fewer opportunities for breast milk pumping sessions for supervising anesthesiologists than an anesthesia resident or nurse anesthetist.

We also deliberately did not consider that the supervising anesthesiologist who needs to leave for a breast milk pumping session may be assigned to give brief breaks to those anesthesia providers they are supervising.²⁵ Previously, we evaluated anesthesiologist presence at all critical portions of cases (e.g., induction, turning patient between supine and prone, and extubation).²⁵ With anesthesiologists responsible for two ORs, but not giving breaks, the surgical suite we studied had 35% of days (lower 95% confidence limit = 30%) with at least one case that either would wait for the anesthesiologist or the anesthesiologist could not be present because the other OR's case was also at a critical portion.²⁵ When the anesthesiologist gave breaks, such occurrences of conflicting responsibilities increased to 62% of days (56%).²⁵ With the supervision of three ORs, the percentages were 99% of days (96%) even when not providing breaks.²⁵

Our results can be expected to be generalizable because surveys more than 10 years ago found that most anesthesiologists' practices involved principally the clinical supervision of anesthesia residents or nurse anesthetists.^6,7 Since then, comparing 2019–2012, anesthesiologist employment in the United States of America has remained stable, but the number of nurse anesthetists has increased by 25%.²⁶ This change implies that many anesthesiologists are supervising more nurse anesthetists (i.e., more ORs) simultaneously than a decade ago. We studied surgical suites at a large teaching hospital. Community hospitals and private ambulatory surgery centers have even briefer total durations of anesthetics.²⁷ Therefore, our conclusions would be even more reliable for such facilities. However, this means generalizability to anesthesiologists supervising multiple ORs. This unique feature of our work presents very different challenges for breast milk pumping compared with those experienced by physicians in other specialties (e.g., with many brief, scheduled outpatient clinic appointments).

Given our quantitative findings, some anesthesiologists who are breastfeeding may consider providing clinical care that overlaps with their training and experience, but does not require supervising >2 ORs. For example, some anesthesia groups have an anesthesiologist in the preoperative clinic. As another example, many U.S. hospitals have obstetrical programs with an in-house practitioner (e.g., working 12-hour shifts) but with too few deliveries for labor epidurals and cesarean sections to result in continuous work.^28,29 The hospital studied is like many nationwide in having surgical suites with lesser productivity on nights and weekends with multiple periods of few simultaneous cases but overnight in-house call because of emergencies.³⁰ Unlike the pediatric hospital studied, nationwide pediatric ambulatory surgery centers have completed 77% (standard error 4%) of total OR time by 12 noon and 94% (3%) of total time by 3:00 PM.³¹ While U.S. academic anesthesia departments in 2019 averaged 7.6 hours of cases per day at their hospitals (standard deviation 2.1), their ambulatory surgery centers averaged only 4.9 (standard deviation 2.9).³² When one large teaching hospital's main campus averaged 7.8 hours of elective cases per OR per workday (standard error <0.1), the affiliated hospitals' surgical suites scattered around the city averaged 3.3–4.7 hours (standard errors ≤0.1 hours).³³ At these facilities with much briefer workdays than those of the studied medical center (Table 1), an anesthesiologist could pump before and after surgery.

One limitation is that our results have substantial implications for women anesthesiologists and their babies, but probably not for encouraging female medical students to train in the specialty. From the U.S. national survey of women anesthesiologists, 11.6% (212/1,830) would “counsel a female student against a career in anesthesiology due to obstacles pertaining to motherhood.”³⁴ The predictive factors were that the “desired age of childbearing/motherhood [was] adversely affected by work demands” and that the “desired number of children [was] adversely affected by work demands” (both p < 0.0001 with adjustment for consideration of the other 32 potential predictors).³⁴ Among the 29.5% (539/1,827) of women who answered “No” to both questions, 4.1% (22/539) would counsel against anesthesiology as a career. In contrast, among the 35.0% (640/1,827) answering “Yes” to both, 20.8% (133/640) would counsel against a career in anesthesiology.³⁴ That is a risk ratio of 5.1 (99% confidence interval 3.3–7.9, p < 0.0001).³⁴ There was no predictive relationship to any factor related to childbirth or breastfeeding during training.³⁴

Another limitation is that we paired ORs within surgical suites based on numerical sequence, close to, but different from adjacency. There are many objectives and constraints to anesthesiologists' assignments (e.g., physical proximity of the covered locations). Alignment at the studied hospital has never been based on prediction intervals of surgical times, given that the methodology was not developed until the current article. Consequently, alternative considerations of pairings of ORs may increase the precision of our estimates (e.g., reduce the 99% confidence interval of Table 1's last three rows from 41–43% to 42–42%), but that would not change the conclusions (e.g., the hypothesis being supported based on exceeding 33%).

In conclusion, even when making multiple assumptions that were deliberately unrealistic (e.g., anesthesiologists' responsibilities are only ongoing cases and not their patients in the postanesthesia care unit), for the large majority (>2/3rd) of surgical cases during regular workdays, anesthesiologists supervising three ORs would not have a reliably long period for a breast milk pumping session. Even when a single OR has a case of sufficient duration that an anesthesia resident or nurse anesthetist could be relieved for a 30-minute breast milk pumping session, often (>1/3rd of such cases) the supervising anesthesiologist would not have such time because of the activity in the other ORs they are supervising. Departments with some anesthesiologists who are breastfeeding should consider having options for temporary clinical assignments, commensurate with training and experience, which do not require supervising >2 ORs.

Footnotes

Authors' Contributions

Dr. Titler helped with conceptualization, writing original draft, and reviewing and editing. Dr. Dexter helped with methodology, software, validation, formal analysis, data curation, writing original draft, reviewing and editing, visualization, and project administration. Dr. Epstein helped with validation, writing original draft, and reviewing and editing.

Disclosure Statement

No competing financial interests exist.

Funding Information

No funding was received for this article.

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