1. Adult patients 18 years or older 2. Individuals undergoing either a mastectomy or mastectomy with tissue expander for which the anesthetic plan includes a serratus anterior plane block. 1. Any known sensory deficit of the anterolateral chest wall. 2. Any local disorder of the skin or otherwise where blockade is to be performed which would prevent safe performance of the block 3. Pregnancy 4. American Society of Anesthesiology classification greater than 3 5. Allergy to amide local anesthetic medications 6. Chronic pain conditions 7. Preoperative opioid use greater than 20 oral morphine equivalents per day 8. Any coagulation abnormality which would be a contraindication for block placement 9. Preoperative chronic renal dysfunction requiring renal replacement therapy or a serum creatinine greater than 1.4 mg/dL 10. Body mass index >50 11. Incarceration 12. Inability to understand study procedures including inability to understand the English language 13. Inability to provide adequate informed consent 14. Refusal to participate in the study

• Adult subjects aged 18 years or older
• Scheduled for elective posterior lumbar spinal fusion surgery between 1 and 3 levels
• Baseline cognitive deficits sufficient to make objective pain self-assessments unreliable in the estimation of the Study Investigators.
• Immunocompromised subject
• Coagulopathy
• Severe liver and renal dysfunction
• Preoperative neurological deficits
• The dura damage during surgery
• Inability to follow directions or comprehend the English language.
• Females who are pregnant as determined by positive pregnancy test on or before the day of surgery.
• Prisoners.
• Patient refusal to provide informed consent.
• Allergy to amide local anesthetics (lidocaine, bupivacaine, ropivacaine) or opioid (fentanyl).

• Pathologically confirmed metastatic breast cancer
• Known estrogen, progesterone, and HER2 status of either primary tumor or metastasis
• ≤ 4 metastases seen on standard imaging within 60 days prior to registration when all metastatic disease is located within the following sites:
• peripheral lung
• osseous (bone)
• spine
• central lung
• abdominal-pelvic(lymph node/adrenal gland)
• liver
• mediastinal/cervical lymph node
• All known disease amenable to metastasis-directed therapy with either SBRT or resection
• NOTE: Symptomatic bone metastasis are allowed if ablative therapy can be delivered
• NOTE: Sites for possible surgical excision include lung, liver, adrenal gland, bone, small intestine, large intestine, ovary, and amenable nodal disease sites
• NOTE: Surgical stabilization is allowed for a metastasis if it is followed by conventionally fractionated external beam radiotherapy
• Maximum diameter of individual metastasis in any dimension ≤ 5 cm
• There are no restrictions on distance between the metastases
• Patients must be registered within 365 days of the initial metastatic breast cancer diagnosis. First-line standard systemic therapy (chemotherapy, anti-endocrine therapy, anti-HER2 or other standard targeted therapy) for metastatic breast cancer must be given or planned to be given. If given before study entry, it cannot have exceeded a duration of 12 months at the time of registration. (Note: Sequencing of ablative therapy (surgery or SBRT) relative to systemic therapy, for patients randomized to Arm 2, is at the discretion of the treating physician.)
• The primary tumor site must be controlled prior to registration
• For those who present with synchronous primary and oligometastatic disease: Primary must be controlled prior to registration. The definition of control is definitive surgery by excision or mastectomy (+/- radiotherapy) per institution preference
• For those who present with local recurrence and oligometastatic disease, local recurrence must be controlled prior to registration The definition of control is definitive surgery by excision or mastectomy (+/- radiotherapy) per institution preference
• Appropriate stage for study entry based on the following diagnostic workup:
• History/physical examination within 60 days prior to registration
• Clinical grade computed tomography (CT) scans of the chest, abdomen, and pelvis with radionuclide bone scan OR whole body positron emission tomography (PET)/CT within 60 days prior to study registration
• Zubrod performance status ≤ 2 within 60 days prior to registration
• Absolute neutrophil count (ANC) ≥ 500 cells/mm^3
• Platelets ≥ 50,000 cells/mm^3
• Hemoglobin ≥ 8.0 g/dl (note: the use of transfusion or other intervention to achieve hemoglobin [Hgb] ≥ 8.0 g/dl is acceptable)
• For females of child-bearing potential, negative serum or urine pregnancy test within 14 days prior to study registration
• Pathologic evidence of local/regional breast tumor recurrence at the time of registration
• Co-existing or prior invasive malignancy (except non-melanomatous skin cancer), unless disease free for a minimum of 3 years; previous RT dose, date, fraction size, must be reported
• Metastases with indistinct borders making targeting not feasible
• NOTE: A potential issue with bone metastases is that they often are not discrete. Since many patients on this protocol will have bone metastases, this will be an important issue. Theoretically, Houndsfield units might provide an appropriate measure; however, a sclerotic lesion against dense cortical bone will not have a sharp demarcation based on Houndsfield units (HU). Therefore, we acknowledge that such determinations will pose a challenge and thus the physician's judgment will be required
• Prior palliative radiation treatment for metastatic disease (including radiopharmaceuticals)
• Metastases located within 3 cm of the previously irradiated structures:
• Spinal cord previously irradiated to > 40 Gy (delivered in ≤ 3 Gy/fraction)
• Brachial plexus previously irradiated to > 50 Gy (delivered in ≤ 3 Gy/fraction)
• Small intestine, large intestine, or stomach previously irradiated to > 45 Gy (delivered in ≤ 3 Gy/fraction)
• Brainstem previously irradiated to > 50 Gy (delivered in ≤ 3 Gy/fraction)
• Whole lung previously irradiated with prior V20Gy > 30% (delivered in ≤ 3 Gy/fraction)
• Primary tumor irradiated with SBRT
• Metastasis irradiated with SBRT
• Brain metastases
• Exudative, bloody, or cytological proven malignant effusions
• Severe, active co-morbidity defined as follows:
• Unstable angina and/or congestive heart failure requiring hospitalization within the last 6 months
• Transmural myocardial infarction within the last 6 months
• Acute bacterial or fungal infection requiring intravenous antibiotics at the time of registration
• Chronic obstructive pulmonary disease exacerbation or other respiratory illness requiring hospitalization or precluding study therapy at the time of registration
• Pregnancy; lactating females must cease expression of milk prior to signing consent to be eligible
• Human immunodeficiency virus (HIV) positive with cluster of differentiation (CD)4 count < 200 cells/microliter; note that patients who are HIV positive are eligible, provided they are under treatment with highly active antiretroviral therapy (HAART) and have a CD4 count ≥ 200 cells/microliter within 30 days prior to registration; note also that HIV testing is not required for eligibility for this protocol

• 18-75 years old
• ASA 1-2
• BMI 19-35 kg/m2
• Patients undergoing surgery with general anesthesia with sevoflurane- fentanyl
• Planned abdominal or spinal surgery lasting 1-3 hours
• Willing and able to consent in English or Spanish
• No current history of advanced pulmonary or cardiovascular disease
• Age less than 18 or older than 75
• Patient does not speak English or Spanish
• Patient refusal
• Monitored anesthesia care (MAC) or regional anesthesia planned
• Pregnant or nursing women
• "Stat" (emergent) cases
• ECG rhythm other than regular sinus rhythm
• Implanted pacemakers
• On antimuscarinic agents, alpha 2 agonists, antiarrhythmics, or beta blockers
• Presence of pacemaker
• Autonomic nervous system disorder
• Use of chronic opioids

1. Is male or female <2 years of age at the time of surgery. 2. Must weigh at least 3 kg. 3. Is scheduled to have a surgical procedure for which opioid analgesia will be needed to manage postoperative pain for at least 18 hours following intraoperative and/or postoperative IV analgesia. 4. Is generally healthy as documented by medical history; physical examination (including, but not limited to, the cardiovascular, gastrointestinal, respiratory, and central nervous systems); vital sign assessments; 12-lead electrocardiograms (EKGs); clinical laboratory assessments; and general observations. Any abnormalities or deviations from the acceptable range that might be considered clinically relevant by the study physician or investigator will be evaluated on a case-by-case basis, agreed upon by the Principal Investigator (or sub-investigator), and documented in study files before enrolling the subject in the study. 5. The subject's parent or guardian has been informed of the nature of the study and has provided written informed consent. Postoperative: 6. Is anticipated to require an analgesic regimen using a short-acting opioid (non-oxycodone and non-oxymorphone) analgesic after surgery (according to standard of care (SOC) as defined in the protocol). 7. Is an inpatient expected to be hospitalized for 24 hours after dosing with study drug. 8. Has an indwelling access catheter for blood sampling. 9. Has demonstrated the ability to tolerate clear fluids following surgery according to the SOC at each institution. All infants and children should be able to demonstrate strong suck and swallow reflexes and neurologic alertness and stability sufficient to handle oral secretions. The ability to tolerate small amounts (1 to 2 oz.) of clear liquids without emesis (over 30 to 60 minutes) would support readiness for study participation and oral intake once the physician has ordered the diet advanced to clear liquids and the subject has ingested fluids by mouth without nausea or vomiting. 1. Has the presence or history of a clinically significant disorder involving the cardiovascular, respiratory, renal, gastrointestinal, immunologic, hematologic, endocrine, or nervous system(s) or psychiatric disease that would contraindicate participation, as determined by the Investigator. 2. Has any clinical laboratory test result outside the accepted range that has been confirmed upon re-examination and deemed to be clinically significant. 3. Has a clinically significant illness or condition any time before dosing with study drug that would contraindicate participation, as determined by the Investigator. 4. Has a life expectancy <8 weeks. 5. For age groups A and B: Has a malabsorption, gastroenterologic, or abdominal condition that would interfere with the absorption of study drug. 6. Has evidence of increased intracranial pressure. 7. Has a respiratory condition requiring intubation or resulting in active bronchiolitis, asthma, stridor, or difficulty breathing due to congestion and increased nasal secretions, including oxygen (O2) saturation ≤92%. 8. Has a history of seizures. 9. Subject (and/or mother if subject is nursing) has used medications with actions characteristic of monoamine oxidase inhibitors (MAOIs) within 14 days before the start of the study drug is prohibited. Standard daily pediatric multivitamins may be taken until enrollment into the study but will be restricted during the study. 10. Subject (and/or mother if subject is nursing) has received preoperative opioids for more than 72 consecutive hours. 11. Subject (and/or mother if subject is nursing) has received oxycodone or oxymorphone within 48 hours prior to screening. 12. Subject (and/or mother if subject is nursing) has ingested caffeine- or xanthine-containing products (eg, theophylline) within 48 hours before dosing. These products are also prohibited during periods when blood samples are collected. 13. Has a history of relevant drug allergies, food allergies, or both (ie, allergy to oxymorphone or other opioid analgesics) that could interfere with the study. 14. Parent or legal guardian is unable to provide consent for any reason (eg, mental or physical disabilities, language barriers, or is unavailable). 15. Subject (and/or mother if subject is nursing) has participated in a clinical study of an unapproved drug within the previous 30 days. 16. Is not suitable for entry into the study in the opinion of the Investigator.

• Younger than 2 years (chronological age)
• Scheduled for anaesthesia that is expected to last at least 2 hours (and/or total operating room time is scheduled to be at least 2.5 hours)
• Has a legally acceptable representative capable of understanding the informed consent document and providing consent on the participant's behalf.
• Known neurologic, chromosomal or congenital anomaly which is likely to be associated with poor neurobehavioural outcome
• Existing diagnosis of behavioural or neurodevelopmental disability
• Prematurity (defined as < 36 weeks gestational age at birth)
• Birth weight less than 2 kg.
• Congenital cardiac disease requiring surgery
• Intracranial neurosurgery and intracranial craniofacial surgery (isolated cleft lip is not an exclusion)
• Previous cumulative exposure to general anaesthesia exceeding 2 hours
• Planned future cumulative exposure to anaesthesia exceeding 2 hours before the age of 3 years.
• Any specific contra-indication to any aspect of the protocol
• Previous adverse reaction to any anaesthetic
• Circumstances likely to make long term follow-up impossible
• Living in a household where the primary language spoken at home is not a language in which we can administer the Wechsler Preschool and Primary School Intelligence Scale
• Planned postoperative sedation with any agent except opioids (e.g. benzodiazepines, dexmedetomidine, ketamine, barbiturates, propofol, clonidine, chloral hydrate, and other non-opioid sedatives). For example if such sedation is planned for post-operative ventilation

1. Has a parent or guardian providing written parental permission/informed consent, with subject assent (if required by local IRB). 2. Has an age-appropriate pain score of ≥4 prior to receiving first dose of study drug. 3. Is a child 2 years old through 17 years old, inclusive (at the time of informed consent signing). 4. Weighs at least 10 kg. 5. Has a routine pediatric procedure that is expected to require inpatient hospitalization postoperatively. 6. Must be an inpatient for the study treatment period. 7. Is expected by the investigator to have moderate to severe postoperative pain requiring the use of oral opioids for treatment. 8. Has the ability to read and understand the study procedures and has the ability to communicate meaningfully with the study investigator and staff (if the subject is of preverbal age or cannot read or communicate meaningfully, then the subject's parent or guardian must meet this criterion). 9. Is able to tolerate oral medications within 48 hours of surgery. 10. If female subject is of childbearing potential, she must have a negative urine pregnancy test result on the day of surgery prior to surgery. In this population, female of childbearing potential is defined by the onset of menarche, ie, menstruation, whether at irregular or regular intervals (periods). 11. Female subjects of childbearing potential and male subjects with partners capable of reproduction must agree to use an effective contraceptive method as follows from the time of Screening through 30 days after the last dose of study drug:
• A highly effective method of contraception, including hormonal contraceptives (eg, combined oral contraceptives, patch, vaginal ring, injectables, and implants), intrauterine device or intrauterine system OR
• An effective double-barrier contraceptive method (2 of the following: male condom, female condom, cervical cap, diaphragm, or contraceptive sponge) OR
• Abstinence 12. Must have vascular access to facilitate blood draws. 1. Has significant medical disease(s), laboratory abnormalities, or conditions(s) that in the investigator's judgment could compromise the subject's welfare, ability to communicate with study staff, complete study activities, or would otherwise contraindicate study participation. There is no minimum value for SpO2 for inclusion in the study; this should be based on the investigator's judgment. 2. Has used opioids chronically (eg, codeine, morphine, oxycodone, or hydromorphone), for >7 calendar days within the previous 30 days prior to surgery. 3. Has received codeine, hydrocodone, morphine or oxycodone in any form in the previous 7 calendar days prior to surgery. 4. Is undergoing procedure for treatment of acute burns. 5. Has known hypersensitivity or contraindication to receiving oral opioid(s). 6. Has a current active enteral malabsorption disorder. 7. Has impaired liver function (eg, alanine aminotransferase [ALT] ≥3 times the upper limit of normal [ULN], or total bilirubin ≥2 times ULN [except patients with evidence of Gilbert's syndrome]), known active hepatic disease (eg, hepatitis), evidence of clinically significant chronic liver disease or other condition affecting the liver (eg, chronic hepatitis) that may suggest the potential for an increased susceptibility to hepatic toxicity with oral morphine exposure. Subjects with no previous history of liver function impairment may be enrolled prior to receipt of screening laboratory testing results. 8. Has significantly impaired renal function or disease, as evidenced by an estimated glomerular filtration rate (ie, from creatinine levels using the Schwartz formula) calculated to be less than one-third of normal for the applicable age of this study population. Subjects with no previous history of kidney function impairment may be enrolled prior to receipt of screening laboratory testing results. 9. Has a history of substance abuse or there is evidence of current substance abuse, in the investigator's opinion. 10. Has received epidural or regional anesthesia within 12 hours prior to the first dose of study drug. 11. Has participated in an interventional clinical study (investigational or marketed product) within 30 days before screening, or plans to participate in another clinical trial in the next 30 days.

• 18-70 years old
• ASA physical status classification 1 to 3
• Personal history of cocaine abuse
• Scheduled for a non-emergent operation that requires general anesthesia
• Vital signs within generally accepted ranges for normal [HR 60-100, RR 12-20, SpO2 > 96% on room air, BP 90-140/60-90 unless a diagnosis of hypertension is present, T 36-38 degrees)
• Willing and able to consent in English or Spanish
• Age less than 18 or older than 70
• Unable to give informed consent for participation in the study
• Patient refusal
• Monitored anesthesia care (MAC) or regional anesthesia planned
• Pregnant or lactating
• Emergent surgery
• Acute cocaine intoxication based on clinical symptomatology (hypertension, tachycardia, agitation, delirium, hyperthermia)
• History of cardiac disease including coronary artery disease (CAD) and cardiac dysrhythmia
• History of stroke
• History of seizure disorder
• ESRD
• Prison patient