Other Respiratory System O.R. Procedures with MCC: Inpatient Reimbursement Overview

DRG 166 addresses other respiratory system operations performed in the operating room when a Major Complication or Comorbidity is present, covering higher-acuity thoracic and airway procedures. This Diagnosis-Related Group matters for inpatient reimbursement because the presence of a Major Complication or Comorbidity increases expected resource use and thus affects Medicare payment.

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DRG 166 Overview

DRG 166 encompasses inpatient cases involving other respiratory system operations performed in the operating room with a Major Complication or Comorbidity present. It covers a range of thoracic and airway surgical procedures that are more resource-intensive due to the presence of severe comorbid conditions. This Diagnosis-Related Group is important for Medicare payment because the Major Complication or Comorbidity elevates expected resource use and hospital reimbursement relative to lower-severity groups. Accurate clinical documentation and coding determine assignment to this Diagnosis-Related Group and associated payment level.

Clinical Trials

Acute perioperative airway management and complication reduction trials: randomized or observational studies testing protocols, devices, or intraoperative monitoring strategies to reduce immediate respiratory complications in patients undergoing complex thoracic or upper airway operations that fall under ‘other respiratory system O.R. procedures’ with major complications or comorbidities (MCC). These studies enroll high-risk inpatients (often with severe chronic lung disease, obesity, or cardiac comorbidity) undergoing procedures such as tracheal reconstruction, complex bronchoscopy with therapeutic intervention, or pleural/mediastinal surgery, and measure outcomes like intraoperative hypoxia, need for emergent reintubation, and ICU transfer. Results are highly relevant to providers for refining perioperative protocols and to payers because reductions in acute complications drive shorter ICU stays, fewer returns to the OR, and lower incremental costs associated with MCC-level resource use.
Comparative effectiveness research on surgical approaches and perioperative bundles: pragmatic trials or large registry-based comparative studies evaluating different operative techniques (minimally invasive versus open approaches), anesthesia strategies, or standardized perioperative care bundles for patients with complex respiratory pathology requiring OR procedures. These studies target heterogeneous inpatient cohorts with comorbid respiratory failure, infectious or obstructive airway disease, or prior thoracic surgery, and assess outcomes such as operative morbidity, length of stay, readmission, and complication-driven resource utilization. Findings inform clinical decision-making about the most cost-effective strategies for managing high-cost DRG 166 cases and help payers and hospitals prioritize investments in surgical capability and care pathways that reduce MCC-associated expenditures.
Post-discharge and long-term outcomes and resource utilization studies: prospective cohort studies or health-services research examining functional recovery, pulmonary rehabilitation needs, readmission rates, and long-term healthcare utilization among survivors of complex respiratory O.R. procedures with MCCs. These studies follow patients after hospital discharge—often those with prolonged ventilation, tracheostomy, or significant functional decline—to quantify subsequent home health, outpatient pulmonary services, and rehospitalization risk, and to identify predictors of costly post-acute care. Such research is crucial for providers planning discharge and rehabilitation, and for payers modeling total episode-of-care costs and designing care-management programs to reduce preventable post-discharge expenditure.

Related Codes

163-MAJOR-CHEST-PROCEDURES-WITH-MCC

Major Chest Procedures with MCC: Inpatient Reimbursement Overview

164-MAJOR-CHEST-PROCEDURES-WITH-CC

Major Chest Procedures with CC: Inpatient Reimbursement Overview

165-MAJOR-CHEST-PROCEDURES-WITHOUT-CC-MCC

Major Chest Procedures without CC/MCC: Inpatient Reimbursement Overview

167-OTHER-RESPIRATORY-SYSTEM-O-R-PROCEDURES-WITH-CC

Other Respiratory System O.R. Procedures with CC: Inpatient Reimbursement Overview

168-OTHER-RESPIRATORY-SYSTEM-O-R-PROCEDURES-WITHOUT-CC-MCC

Other Respiratory System O.R. Procedures without CC/MCC: Inpatient Reimbursement Overview

173-ULTRASOUND-ACCELERATED-AND-OTHER-THROMBOLYSIS-WITH-PRINCIPAL-DIAGNOSIS-PULMONARY-EMBOLISM

Ultrasound Accelerated and Other Thrombolysis with Principal Diagnosis Pulmonary Embolism: Inpatient Reimbursement Overview

175-PULMONARY-EMBOLISM-WITH-MCC-OR-ACUTE-COR-PULMONALE

Pulmonary Embolism with MCC or Acute Cor Pulmonale: Inpatient Reimbursement Overview

176-PULMONARY-EMBOLISM-WITHOUT-MCC

Pulmonary Embolism without MCC: Inpatient Reimbursement Overview

177-RESPIRATORY-INFECTIONS-AND-INFLAMMATIONS-WITH-MCC

Respiratory Infections and Inflammations with MCC: Inpatient Reimbursement Overview

178-RESPIRATORY-INFECTIONS-AND-INFLAMMATIONS-WITH-CC

Respiratory Infections and Inflammations with CC: Inpatient Reimbursement Overview

Showing 1–10 of 40

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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Clinical Trials

Acute perioperative airway management and complication reduction trials: randomized or observational studies testing protocols, devices, or intraoperative monitoring strategies to reduce immediate respiratory complications in patients undergoing complex thoracic or upper airway operations that fall under ‘other respiratory system O.R. procedures’ with major complications or comorbidities (MCC). These studies enroll high-risk inpatients (often with severe chronic lung disease, obesity, or cardiac comorbidity) undergoing procedures such as tracheal reconstruction, complex bronchoscopy with therapeutic intervention, or pleural/mediastinal surgery, and measure outcomes like intraoperative hypoxia, need for emergent reintubation, and ICU transfer. Results are highly relevant to providers for refining perioperative protocols and to payers because reductions in acute complications drive shorter ICU stays, fewer returns to the OR, and lower incremental costs associated with MCC-level resource use.
Comparative effectiveness research on surgical approaches and perioperative bundles: pragmatic trials or large registry-based comparative studies evaluating different operative techniques (minimally invasive versus open approaches), anesthesia strategies, or standardized perioperative care bundles for patients with complex respiratory pathology requiring OR procedures. These studies target heterogeneous inpatient cohorts with comorbid respiratory failure, infectious or obstructive airway disease, or prior thoracic surgery, and assess outcomes such as operative morbidity, length of stay, readmission, and complication-driven resource utilization. Findings inform clinical decision-making about the most cost-effective strategies for managing high-cost DRG 166 cases and help payers and hospitals prioritize investments in surgical capability and care pathways that reduce MCC-associated expenditures.
Post-discharge and long-term outcomes and resource utilization studies: prospective cohort studies or health-services research examining functional recovery, pulmonary rehabilitation needs, readmission rates, and long-term healthcare utilization among survivors of complex respiratory O.R. procedures with MCCs. These studies follow patients after hospital discharge—often those with prolonged ventilation, tracheostomy, or significant functional decline—to quantify subsequent home health, outpatient pulmonary services, and rehospitalization risk, and to identify predictors of costly post-acute care. Such research is crucial for providers planning discharge and rehabilitation, and for payers modeling total episode-of-care costs and designing care-management programs to reduce preventable post-discharge expenditure.

Related Codes

163-MAJOR-CHEST-PROCEDURES-WITH-MCC

Major Chest Procedures with MCC: Inpatient Reimbursement Overview

164-MAJOR-CHEST-PROCEDURES-WITH-CC

Major Chest Procedures with CC: Inpatient Reimbursement Overview

165-MAJOR-CHEST-PROCEDURES-WITHOUT-CC-MCC

Major Chest Procedures without CC/MCC: Inpatient Reimbursement Overview

167-OTHER-RESPIRATORY-SYSTEM-O-R-PROCEDURES-WITH-CC

Other Respiratory System O.R. Procedures with CC: Inpatient Reimbursement Overview

168-OTHER-RESPIRATORY-SYSTEM-O-R-PROCEDURES-WITHOUT-CC-MCC

Other Respiratory System O.R. Procedures without CC/MCC: Inpatient Reimbursement Overview

173-ULTRASOUND-ACCELERATED-AND-OTHER-THROMBOLYSIS-WITH-PRINCIPAL-DIAGNOSIS-PULMONARY-EMBOLISM

Ultrasound Accelerated and Other Thrombolysis with Principal Diagnosis Pulmonary Embolism: Inpatient Reimbursement Overview

175-PULMONARY-EMBOLISM-WITH-MCC-OR-ACUTE-COR-PULMONALE

Pulmonary Embolism with MCC or Acute Cor Pulmonale: Inpatient Reimbursement Overview

176-PULMONARY-EMBOLISM-WITHOUT-MCC

Pulmonary Embolism without MCC: Inpatient Reimbursement Overview

177-RESPIRATORY-INFECTIONS-AND-INFLAMMATIONS-WITH-MCC

Respiratory Infections and Inflammations with MCC: Inpatient Reimbursement Overview

178-RESPIRATORY-INFECTIONS-AND-INFLAMMATIONS-WITH-CC

Respiratory Infections and Inflammations with CC: Inpatient Reimbursement Overview

Showing 1–10 of 40

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.