Arterial Catheters for Early Detection and Treatment of Hypotension During Major Noncardiac Surgery: A Randomized Trial

BACKGROUND

Continuous blood pressure monitoring may facilitate early detection and prompt treatment of hypotension. We tested the hypothesis that area under the curve (AUC) mean arterial pressure (MAP) <65 mm Hg is reduced by continuous invasive arterial pressure monitoring.

METHODS

Adults having noncardiac surgery were randomly assigned to continuous invasive arterial pressure or intermittent oscillometric blood pressure monitoring. Arterial catheter pressures were recorded at 1-minute intervals; oscillometric pressures were typically recorded at 5-minute intervals. We estimated the arterial catheter effect on AUC-MAP <65 mm Hg using a multivariable proportional odds model adjusting for imbalanced baseline variables and duration of surgery. Pressures <65 mm Hg were categorized as 0, 1-17, 18-91, and >91 mm Hg × minutes of AUC-MAP <65 mm Hg (ie, no hypotension and 3 equally sized groups of increasing hypotension).

RESULTS

One hundred fifty-two patients were randomly assigned to arterial catheter use and 154 to oscillometric monitoring. For various clinical reasons, 143 patients received an arterial catheter, while 163 were monitored oscillometrically. There were a median [Q1, Q3] of 246 [187, 308] pressure measurements in patients with arterial catheters versus 55 (46, 75) measurements in patients monitored oscillometrically. In the primary intent-to-treat analysis, catheter-based monitoring increased detection of AUC-MAP <65 mm Hg, with an estimated proportional odds ratio (ie, odds of being in a worse hypotension category) of 1.78 (95% confidence interval [CI], 1.18-2.70; P = .006). The result was robust over an as-treated analysis and for sensitivity analyses with thresholds of 60 and 70 mm Hg.

CONCLUSIONS

Intraoperative blood pressure monitoring with arterial catheters detected nearly twice as much hypotension as oscillometric measurements.

Return to sporting activity after ulnar nerve transposition for isolated neuritis in competitive overhead athletes

BACKGROUND

Although ulnar neuritis can occur secondary to ulnar collateral ligament pathology, stress fractures, and traction apophysitis, isolated ulnar nerve dysfunction can lead to medial elbow pain. The purpose of this study was to evaluate the short-term outcomes of overhead athletes undergoing anterior ulnar nerve transposition for ulnar neuropathy.

METHODS

All overhead athletes who underwent isolated ulnar nerve transposition between 2009 and 2016 for refractory ulnar neuritis were identified. The primary outcome was return to sport, and secondary outcome measures included the Kerlan-Jobe Orthopaedic Clinic score; Mayo Elbow Performance Score; Quick Disabilities of the Arm, Shoulder and Hand score; Single Assessment Numeric Evaluation score; and visual analog scale score for pain. Complication and reoperation rates were recorded.

RESULTS

A total of 26 overhead athletes (21 male and 5 female athletes) underwent ulnar nerve transposition at an average age of 18.4 years (range, 11-25 years). Of the patients, 24 (92%) returned to their sporting activity at an average of 2.7 months postoperatively, including 16 (62%) at the previous level of play. The average visual analog scale pain score improved from 4.7 (±2.5) to 0.4 (±1.5) (P = .015). The average postoperative patient-reported outcome scores were as follows: Kerlan-Jobe Orthopaedic Clinic score, 80 (95% confidence interval [CI], 72.7-87.0); Single Assessment Numeric Evaluation score, 85 (95% CI, 75.4-94.7); Quick Disabilities of the Arm, Shoulder and Hand score, 5 (95% CI, 2.1-7.7); and Mayo Elbow Performance Score, 91 (95% CI, 86.8-96.0).

CONCLUSION

Cubital tunnel syndrome can cause medial elbow pain in overhead athletes in the presence of a normal ulnar collateral ligament. At mid-term follow-up, 92% of overhead athletes returned to sport after ulnar nerve transposition, with 62% resuming their previous level of performance.

Salvage reverse total shoulder arthroplasty for failed anatomic total shoulder arthroplasty: a cohort analysis

BACKGROUND

Reverse total shoulder arthroplasty (RTSA) as a revision procedure for failed anatomic total shoulder arthroplasty (TSA) is increasing in incidence. The purpose of this study was to analyze the results of RTSA as a revision salvage procedure for failed TSA and identify factors that influenced those outcomes.

METHODS

All anatomic TSAs that were revised to RTSAs in adult patients, under the care of 2 senior surgeons at a single academic center from 2006 to 2018, were queried and reviewed. Cases in which hemiarthroplasty or RTSA was revised to RTSA were excluded. Electronic medical records and survey databases were reviewed for each subject. Demographic and surgical details were reviewed and analyzed with descriptive statistics. Preoperative and postoperative range of motion (ROM) including active forward elevation and active external rotation were evaluated. Patient-reported outcome surveys including the American Shoulder and Elbow Surgeons survey, Single Assessment Numeric Evaluation, and visual analog scale for pain were collected and analyzed. Improvement in ROM and outcome survey measures was assessed with 2-sample t tests. Complication and reoperation rates were analyzed with descriptive statistics.

RESULTS

A total of 75 patients (32 men and 43 women) were available for analysis at a mean of 22.3 months. The subjects were aged 60.3 ± 11.3 years at the time of TSA and 64.6 ± 9.7 years at the time of RTSA. The average period between TSA and RTSA was 4.3 years. The 3 most common indications for revision RTSA were painful arthroplasty (n = 62, 82.7%), rotator cuff failure (n = 56, 74.7%), and unstable arthroplasty (n = 25, 33.3%), but the majority of patients had multiple indications for surgery (n = 69, 92%). Significant improvements were found in all outcome measures from the time of failed TSA diagnosis to most recent follow-up after salvage RTSA with the exception of active external rotation: American Shoulder and Elbow Surgeons score, 39 ± 15 preoperatively vs. 62 ± 25 postoperatively; Single Assessment Numeric Evaluation, 27 ± 23 vs. 60 ± 30; visual analog scale pain score, 5 ± 2 vs. 3 ± 3; and active forward elevation, 79° ± 41° vs. 128° ± 33°. Major complications occurred in 21 patients (28.4%) after salvage RTSA, and 9 (12%) underwent reoperation.

CONCLUSIONS

RTSA for failed TSA can improve pain, function, and quality-of-life measures in patients with various TSA failure etiologies. However, postoperative ROM and patient-reported outcomes do not reach the values seen in the primary RTSA population.

Anatomic total shoulder arthroplasty with an inlay glenoid component: clinical outcomes and return to activity

BACKGROUND

Biomechanical studies show that inlay glenoid components in total shoulder arthroplasty (TSA) can reduce edge loading and opposite-edge lift-off forces with humeral translation compared with onlay glenoids. However, clinical data for these implants are lacking. We report clinical outcomes and return to activities after anatomic TSA with an inlay glenoid component and a stemless ovoid humeral head in an active, young patient population.

METHODS

A retrospective review of TSA with an inlay glenoid component and an ovoid humeral head component was performed for 27 shoulders. Patients were evaluated with patient-reported outcome measures, range of motion, and radiographs. Return to occupational and sporting activity, complications, and reoperations were analyzed.

RESULTS

A total of 27 shoulders were available for minimum 2-year follow-up. Age averaged 52.1 years, and 92.6% of shoulders were in male patients. The preoperative Walch grade was A1 or A2 in 15 shoulders (55%), B1 in 8 (30%), and B2 in 4 (15%). Patients showed significant improvements in patient-reported outcome measures, active forward flexion, and external rotation (P < .001) with no reoperations. At an average of 3.7 months, the rate of return to work was 92.6%, with 76.0% of those patients returning to their preoperative occupational demand level. At an average of 9.1 months, 75% of patients who responded to our custom survey returned to sport, with 50% achieving the same level or a higher level of sporting activity. Annual postoperative radiographs revealed no inlay component loosening.

CONCLUSION

Anatomic TSA with an inlay glenoid coupled with a stemless ovoid humeral head in an active population resulted in improved clinical outcomes, no reoperations or radiographic loosening, and a high rate of return to activity at shorter-term follow-up.

Next-generation sequencing for diagnosis of infection: is more sensitive really better?

BACKGROUND

The utility of next-generation sequencing (NGS) in differentiating between active infection and contaminant or baseline flora remains unclear. The purpose of this study is to compare NGS with culture-based methods in primary shoulder arthroplasty.

METHODS

A prospective series of primary shoulder arthroplasty patients with no history of infection or antibiotic use within 60 days of surgery was enrolled. All patients received standard perioperative antibiotics. After skin incision, a 10 × 3-mm sample of the medial skin edge was excised. A 2 × 2-cm synovial tissue biopsy was taken from the rotator interval after subscapularis takedown. Each sample set was halved and sent for NGS and standard cultures.

RESULTS

Samples from 25 patients were analyzed. Standard aerobic/anaerobic cultures were positive in 10 skin samples (40%, 95% confidence interval [CI] 20%-60%) and 3 deep tissue samples (12%, 90% CI 1%-23%]). NGS detected ≥1 bacterial species in 17 of the skin samples (68%, 95% CI 49%-87%) and 7 deep tissue samples (28%, 95% CI 9%-47%). There was a significant difference (P < .03) in the mean number of bacterial species detected with NGS between the positive standard culture (1.6 species) and the negative standard culture groups (5.7 species).

CONCLUSION

NGS identified bacteria at higher rates in skin and deep tissue samples than standard culture did in native, uninfected patients undergoing primary procedures. Further research is needed to determine which NGS results are clinically relevant and which are false positives before NGS can be reliably used in orthopedic cases.

The Association Between Timing of Routine Preoperative Blood Testing and a Composite of 30-Day Postoperative Morbidity and Mortality

BACKGROUND

Laboratory testing is a common component of preanesthesia evaluation and is designed to identify medical abnormalities that might otherwise remain undetected. While blood testing might optimally be performed shortly before surgery, it is often done earlier for practical reasons. We tested the hypothesis that longer periods between preoperative laboratory testing and surgery are associated with increased odds of having a composite of 30-day morbidity and mortality.

METHODS

We obtained preoperative data from 2,320,920 patients in the American College of Surgeons National Surgical Quality Improvement Program who were treated between 2005 and 2012. Our analysis was restricted to relatively healthy patients with American Society of Anesthesiology physical status I-II who had elective surgery and normal blood test results (n = 235,010). The primary relationship of interest was the odds of 30-day morbidity and mortality as a function of delay between preoperative testing and surgery. A multivariable logistic regression model was used for the 10 pairwise comparisons among the 5 laboratory timing groups (laboratory blood tests within 1 week of surgery; 1-2 weeks; 2-4 weeks; 1-2 months; and 2-3 months) on 30-day morbidity, adjusting for any imbalanced baseline covariables and type of surgery.

RESULTS

A total of 4082 patients (1.74%) had at least one of the component morbidities or died within 30-days after surgery. The observed incidence (unadjusted) was 1.7% when the most recent laboratory blood tests measured within 1 week of surgery, 1.7% when it was within 1-2 weeks, 1.8% when it was within 2-4 weeks, 1.7% when it was between 1 and 2 months, and 2.0% for patients with most recent laboratory blood tests measured 2-3 months before surgery. None of the values within 2 months differed significantly: estimated odds ratios for patients within blood tested within 1 week were 1.00 (99.5% confidence interval, 0.89-1.12) as compared to 1-2 weeks, 0.88 (0.77-1.00) for 2-4 weeks, and 0.95 (0.79-1.14) for 1-2 months, respectively. The estimated odds ratio comparing 1-2 weeks to each of 2-4 weeks and 1-2 months were 0.88 (0.76-1.03) and 0.95 (0.78-1.16), respectively. Blood testing 2-3 months before surgery was associated with increased odds of outcome compared to patients whose most recent test was within 1 week (P = .002) and 1-2 weeks of the date of surgery.

CONCLUSIONS

In American Society of Anesthesiologists physical status I and II patients, risk of 30-day morbidity and mortality was not different with blood testing up to 2 months before surgery, suggesting that it is unnecessary to retest patients shortly before surgery.

The cost-effectiveness of epidural, patient-controlled intravenous opioid analgesia, or transversus abdominis plane infiltration with liposomal bupivacaine for postoperative pain management

STUDY OBJECTIVE

Intravenous patient-controlled opioid analgesia (IVPCA), epidural analgesia and transversus abdominis plane (TAP) infiltrations are frequently used postoperative pain management modalities. The aim of this study was to conduct a cost-effectiveness analysis comparing the use of epidural, IVPCA, and TAP infiltrations with liposomal bupivacaine for analgesia in the first 72 h postoperatively in patients undergoing major lower abdominal surgery.

DESIGN

Retrospective cost effectiveness analysis.

SETTING

Operating room.

PATIENTS

We obtained data on major lower-abdominal surgeries performed under general anesthesia on adult patients between January 2012 and July 2014.

INTERVENTIONS

A cost-effectiveness analysis was comparing the use of epidural, IVPCA, and TAP infiltrations with liposomal bupivacaine for analgesia in the first 72 h postoperatively.

MEASUREMENTS

A decision analytic model was used to estimate the health outcomes for patients undergoing major lower abdominal surgery. The primary outcome was time-weighted pain from 0 to 72 h after surgery, as measured by numerical rating scale pain scores. The analysis was conducted from the perspective of the hospital as the party responsible for most costs related to surgery.

MAIN RESULTS

From the base case analysis, IVPCA was the optimal strategy regarding cost and effect. TAP with LB, however, was only narrowly dominated, while epidural was clearly dominated. From the sensitivity analysis at willingness-to-pay (WTP) of $150, IV PCA and TAP infiltration were each the optimal strategy for approximately 50% of the iterations. At WTP of $10,000, epidural was only the optimal strategy in 10% of the iterations.

CONCLUSIONS

This is the first study in the literature to compare the cost-effectiveness of epidural, IVPCA, and TAP infiltrations with LB. Within reasonable WTP values, there is little differentiation in cost-effectiveness between IVPCA and TAP infiltration with LB. Epidural does not become a cost-effective strategy even at much higher WTP values.

11 Beta-hydroxysteroid dehydrogenase type 1 regulates synovitis, joint destruction, and systemic bone loss in chronic polyarthritis

OBJECTIVE

In rheumatoid arthritis, the enzyme 11 beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is highly expressed at sites of inflammation, where it converts inactive glucocorticoids (GC) to their active counterparts. In conditions of GC excess it has been shown to be a critical regulator of muscle wasting and bone loss. Here we examine the contribution of 11β-HSD1 to the pathology of persistent chronic inflammatory disease.

METHODS

To determine the contribution of 11β-HSD1 to joint inflammation, destruction and systemic bone loss associated with persistent inflammatory arthritis, we generated mice with global and mesenchymal specific 11β-HSD1 deletions in the TNF-transgenic (TNF-tg) model of chronic polyarthritis. Disease severity was determined by clinical scoring. Histology was assessed in formalin fixed sections and fluorescence-activated cell sorting (FACS) analysis of synovial tissue was performed. Local and systemic bone loss were measured by micro computed tomography (micro-CT). Measures of inflammation and bone metabolism were assessed in serum and in tibia mRNA.

RESULTS

Global deletion of 11β-HSD1 drove an enhanced inflammatory phenotype, characterised by florid synovitis, joint destruction and systemic bone loss. This was associated with increased pannus invasion into subchondral bone, a marked polarisation towards pro-inflammatory M1 macrophages at sites of inflammation and increased osteoclast numbers. Targeted mesenchymal deletion of 11β-HSD1 failed to recapitulate this phenotype suggesting that 11β-HSD1 within leukocytes mediate its protective actions in vivo.

CONCLUSIONS

We demonstrate a fundamental role for 11β-HSD1 in the suppression of synovitis, joint destruction, and systemic bone loss. Whilst a role for 11β-HSD1 inhibitors has been proposed for metabolic complications in inflammatory diseases, our study suggests that this approach would greatly exacerbate disease severity.

Treatment of inflammatory arthritis via targeting of tristetraprolin, a master regulator of pro-inflammatory gene expression

OBJECTIVES

Tristetraprolin (TTP), a negative regulator of many pro-inflammatory genes, is strongly expressed in rheumatoid synovial cells. The mitogen-activated protein kinase (MAPK) p38 pathway mediates the inactivation of TTP via phosphorylation of two serine residues. We wished to test the hypothesis that these phosphorylations contribute to the development of inflammatory arthritis, and that, conversely, joint inflammation may be inhibited by promoting the dephosphorylation and activation of TTP.

METHODS

The expression of TTP and its relationship with MAPK p38 activity were examined in non-inflamed and rheumatoid arthritis (RA) synovial tissue. Experimental arthritis was induced in a genetically modified mouse strain, in which endogenous TTP cannot be phosphorylated and inactivated. In vitro and in vivo experiments were performed to test anti-inflammatory effects of compounds that activate the protein phosphatase 2A (PP2A) and promote dephosphorylation of TTP.

RESULTS

TTP expression was significantly higher in RA than non-inflamed synovium, detected in macrophages, vascular endothelial cells and some fibroblasts and co-localised with MAPK p38 activation. Substitution of TTP phosphorylation sites conferred dramatic protection against inflammatory arthritis in mice. Two distinct PP2A agonists also reduced inflammation and prevented bone erosion. In vitro anti-inflammatory effects of PP2A agonism were mediated by TTP activation.

CONCLUSIONS

The phosphorylation state of TTP is a critical determinant of inflammatory responses, and a tractable target for novel anti-inflammatory treatments.

A nomogram for predicting the need for sciatic nerve block after total knee arthroplasty

PURPOSE

Sciatic nerve block (SNB) is commonly performed in combination with femoral nerve block (FNB) for postoperative analgesia following total knee arthroplasty (TKA). Despite the fact that 10-20 % of TKA patients require SNB for postoperative posterior knee pain, there are no existing studies that suggest a model to predict the need for SNB. The aim of our study was to develop a prediction tool to measure the likelihood of patients undergoing TKA surgery requiring a postoperative SNB.

METHODS

With institutional review board approval, we obtained data from the electronic medical record of patients who underwent TKA at the Cleveland Clinic. A multivariable logistic regression was used to estimate the probability of requiring a postoperative SNB. Clinicians selected potential predictors to create a model, and the potential nonlinear association between continuous predictors and SNB was assessed using the restricted cubic spline model.

RESULTS

In total 6279 TKA cases involving 2329 patients with complete datasets were used for building the prediction model, including 276 (12 %) patients who received a postoperative SNB and 2053 (88 %) patients who did not. The estimated C statistic of the prediction model was 0.64. The nomogram is used by first locating the patient position on each predictor variable scale, which has corresponding prognostic points. The cut-off of 11.6 % jointly maximizes the sensitivity and specificity.

CONCLUSION

This is the first study to be published on SNB prediction after TKA. Our nomogram may prove to be a useful tool for guiding physicians in terms of their decisions regarding SNB.

Postoperative Hypoxemia Is Common and Persistent: A Prospective Blinded Observational Study

BACKGROUND

The incidence, severity, and duration of postoperative oxygen desaturation in the general surgical population are poorly characterized. We therefore used continuous pulse oximetry to quantify arterial oxygen saturation (SpO2) in a cross-section of patients having noncardiac surgery.

METHODS

Oxygen saturation, blinded to clinicians, was recorded at 1-minute intervals in patients >45 years old for up to 48 hours after noncardiac surgery in 1250 patients from Cleveland Clinic Main Campus and 250 patients from the Juravinski Hospital. We determined (1) the cumulative minutes of raw minute-by-minute values below various hypoxemic thresholds; and (2) the contiguous duration of kernel-smoothed (sliding window) values below various hypoxemic thresholds. Finally, we compared our blinded continuous values with saturations recorded during routine nursing care.

RESULTS

Eight hundred thirty-three patients had sufficient data for analyses. Twenty-one percent had ≥10 min/h with raw SpO2 values <90% averaged over the entire recording duration; 8% averaged ≥20 min/h <90%; and 8% averaged ≥5 min/h <85%. Prolonged hypoxemic episodes were common, with 37% of patients having at least 1 (smoothed) SpO2 <90% for an hour or more; 11% experienced at least 1 episode lasting ≥6 hours; and 3% had saturations <80% for at least 30 minutes. Clinical hypoxemia, according to nursing records, measured only in Cleveland Clinic patients (n = 594), occurred in 5% of the monitored patients. The nurses missed 90% of smoothed hypoxemic episodes in which saturation was <90% for at least one hour.

CONCLUSIONS

Hypoxemia was common and prolonged in hospitalized patients recovering from noncardiac surgery. The SpO2 values recorded in medical records seriously underestimated the severity of postoperative hypoxemia.

The role of stromal cells in the persistence of chronic inflammation

Inflammation is an unstable state; it either resolves or persists. Inflammatory reactions often have a propensity for specific anatomical sites. Why inflammation persists with specific tissue tropism remains obscure. Increasing evidence suggests that stromal cells which define tissue architecture are the key cells involved, and therefore make attractive therapeutic targets. Research on stromal cells in general and fibroblasts in particular has so far been hampered by a lack of fibroblast-specific cell markers. This review highlights our increasing understanding of the role of fibroblasts in inflammation, and suggests that these cells provide the cellular basis for site specific chronic inflammation.

Selenium supplementation affects broiler growth performance, meat yield and feather coverage

(1) Selenium (Se) is an essential part of numerous selenoproteins, most of which are involved in the antioxidant system of the body. It is also required by poultry for the maintenance of optimal health and meat quality. This paper reports data from a study examining the effect of dietary source and concentration of selenium on broiler performance and meat quality. (2) Increased dietary selenium content markedly reduced feed conversion ratio (FCR) as a result of significantly lower feed intakes of birds while maintaining the same weight gains. (3) Selenium supplementation increased feathering, with organic selenium (selenised yeast) being superior to inorganic selenium (sodium selenite). (4) Birds receiving organic selenium in their diets had improved eviscerated weight, breast yield and reduced drip loss. (5) There were significant concentration x source interactions on yields of breasts and marylands (thigh plus drumstick), with elevated levels of organic selenium increasing the yields, whereas the opposite was true for the inorganic selenium.

Baby-Friendly Hospital Initiative. Protecting, promoting, and supporting breastfeeding in the twenty-first century

The BFHI is a global UNICEF/WHO-sponsored effort to promote breastfeeding by ensuring that all women are provided with sound information regarding their infant feeding choices and that those who elect to breastfeed their infants are given physiologically sound, evidence-based advice and skilled assistance prenatally and as they begin nursing their infants during their postpartum hospital or birth center stay. The initiative is based on ten policy or procedure statements, The Ten Steps, which were jointly developed and published in 1989 by the sponsoring agencies in consultation with international experts. In 1990, the Ten Steps were accepted as the central theme of the Innocenti Declaration and, later that year, endorsed at the World Summit on Children. In 1992, UNICEF and WHO launched a major international campaign to encourage all hospitals with maternity services to accept the Ten Steps as basic maternity and newborn infant care policies and procedures. These Ten Steps were reviewed briefly in this article. Official designation as Baby Friendly requires a careful assessment completed by a trained external team to confirm that the institution is truly carrying out all Ten Steps and conforming to the International Code of Marketing of Breastmilk Substitutes. During the 8 years since the initiative began, more than 15,000 hospitals in 136 countries have been designated as Baby Friendly. Twenty-seven of these officially designated institutions are in the United States, where the campaign has been active only since 1996. The BFHI is considered one of the most successful international efforts ever performed to protect, promote, and support breastfeeding. Although it does not ensure that mothers will aspire to or achieve the widely accepted goal of approximately 6 months of exclusive breastfeeding, it helps mothers to initiate exclusive nursing, an essential step in the right direction.

Lactation management education for physicians

All health professional groups support breastfeeding as the ideal way to nourish an infant, but numerous surveys have shown that, in general, even perinatal health professionals are not prepared to provide lactation management as part of routine care. Integration of lactation topics into current medical curriculum, whether traditional or problem-based, is the ideal and is possible. Faculty are encouraged to assess the current program for signs of "curriculosclerosis," a prevalent disease characterized by Abrahamson as "hardening of the categories," to look for ways to elasticize the relevant departments, and to integrate lactation management topics at the appropriate place in the larger educational plan. Faculty leadership is crucial. Remedial work, in terms of continuing education, will be necessary for perinatal health professionals until the curriculum model has been in place in preservice and postgraduate programs sufficiently long. Breastfeeding as a primary health care strategy, with its clear health and economic benefits, must be a part of any health care reform and, as such, will be a service expected to be provided by perinatal health professionals.

A study of salicylate and caffeine excretion in the breast milk of two nursing mothers

Salicylate excretion was studied in the breast milk of a nursing mother (Patient A) taking chronic therapeutic doses of aspirin, and caffeine excretion was monitored in the breast milk of a nursing mother (Patient B) who was a heavy coffee drinker. Salicylate concentrations were maximal in serum at 2.25 hours (10.8 mg/dL) and in milk at 3.00 hours (1.0 mg/dL) following 975 mg of aspirin in Patient A. Caffeine concentrations peaked at 5.50 hours in serum (2.14 micrograms/mL) and at 2.00 hours in milk (1.15 micrograms/mL) during a period of steady coffee drinking by Patient B. Milk:serum concentration ratios ranged up to 0.08 for patient A and up to 0.63 for Patient B, demonstrating that relatively more caffeine than salicylate was excreted into milk. Sodium, potassium, pH, and percent solute remained essentially unchanged in milk samples from both patients throughout the study periods so that changes in the state of hydration of pH of the milk could not be implicated for the observed excretion patterns. More than 25 liters of milk at its peak drug concentration would have to be consumed by the infants of Patients A and B respectively to provide the salicylate content of one aspirin tablet or the caffeine content of an average cup of coffee.