13.1 Preoperative Assessment, Preparation & Informed Consent Verification

13.1 Preoperative Assessment, Preparation & Informed Consent Verification

The preoperative phase represents a critical window in perioperative care where comprehensive assessment, patient optimization, and rigorous safety checks significantly reduce morbidity and surgical complications. In Singapore, preoperative care is governed by clinical practice guidelines issued by the Ministry of Health (MOH), institutional standards across public healthcare clusters (SingHealth, National Healthcare Group [NHG], and National University Health System [NUHS]), and the professional framework established by the Singapore Nursing Board (SNB).

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Preoperative Baseline Assessment & Systemic Evaluation

Preoperative assessment establishes a comprehensive baseline of the patient's physical, psychological, and cognitive status. Registered Nurses (RNs) conduct systematic body-system assessments, review diagnostic findings, and identify potential perioperative risks before transferring the patient to the operating theatre (OT).

Systemic Clinical Evaluation Focus Areas

1. Cardiovascular System: Assessment of baseline blood pressure, heart rate, cardiac rhythms, peripheral perfusion, and history of ischaemic heart disease, hypertension, or heart failure. Patients with active cardiac symptoms undergo preoperative electrocardiogram (ECG) and echocardiography as per MOH guidelines.
2. Respiratory System: Evaluation of baseline oxygen saturation (SpO2), lung sound auscultation, smoking history, underlying chronic obstructive pulmonary disease (COPD), or bronchial asthma. Smokers are strongly counseled to cease smoking at least 4 to 8 weeks prior to elective procedures to improve mucociliary clearance and reduce tracheobronchial complications.
3. Renal and Metabolic Function: Baseline renal function tests (Serum Creatinine, Blood Urea Nitrogen, estimated Glomerular Filtration Rate [eGFR]) and electrolyte panels are essential, particularly for patients receiving nephrotoxic contrast agents or undergoing major abdominal/vascular procedures. Baseline HbA1c is evaluated for diabetic patients (targeting < 8.0% prior to elective non-cardiac surgery).
4. Hematological Profile: Review of Full Blood Count (FBC), complete coagulation screens (Prothrombin Time [PT], International Normalized Ratio [INR], Activated Partial Thromboplastin Time [aPTT]), and blood group and crossmatch/type and screen status.
5. Vulnerability and Cognitive Assessment: Evaluation of cognitive baseline using the Abbreviated Mental Test (AMT) or Mini-Mental State Examination (MMSE) to detect preoperative cognitive impairment or baseline dementia, serving as a benchmark for postoperative delirium detection.

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Fasting Protocols & Preoperative Medication Management

Preoperative fasting is essential to minimize gastric volume and acidity, reducing the risk of pulmonary aspiration during anesthesia induction. The MOH Clinical Practice Guidelines enforce standard fasting times for elective surgical procedures.

Preoperative Medication Reconciliation

Nurses must execute precise medication management protocols on the morning of surgery based on institutional pharmacy and anesthesia guidelines:

• Antiplatelets & Anticoagulants: Aspirin may be continued in high-cardiovascular-risk patients unless contraindicated by high bleeding risk procedures (e.g., neurosurgery or spinal surgery). Clopidogrel is typically withheld for 5 to 7 days prior to elective surgery. Direct Oral Anticoagulants (DOACs like dabigatran, rivaroxaban, apixaban) are withheld 24 to 48 hours prior based on renal clearance (eGFR). Warfarin is withheld 5 days prior, with therapeutic bridging using Low Molecular Weight Heparin (LMWH) if indicated.
• Hypoglycaemic Agents: Oral antidiabetic agents (e.g., metformin, sulfonylureas, SGLT2 inhibitors) are withheld on the morning of surgery to prevent hypoglycemia and euglycemic ketoacidosis. Long-acting basal insulin dosage is typically reduced by 20% to 50% on the night before or morning of surgery, with regular Capillary Blood Glucose (CBG) monitoring initiated every 2 to 4 hours.
• Antihypertensives: Essential antihypertensives (such as beta-blockers and calcium channel blockers) are continued with sips of water on the morning of surgery to prevent rebound hypertension or withdrawal tachycardia. Angiotensin-Converting Enzyme Inhibitors (ACE-i) and Angiotensin II Receptor Blockers (ARBs) are frequently withheld 24 hours preoperatively to prevent severe refractory intraoperative hypotension, unless specifically ordered otherwise by the anesthetist.

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Legal & Ethical Dimensions of Informed Consent Verification

In Singapore, obtaining informed consent is legally the primary responsibility of the operating surgeon performing the procedure. However, under the SNB Code for Nurses and Midwives (2023) and Singapore legal doctrine (Hii Chii Kok v OOI Stratford Global Health Care [2017] SGCA 38), the RN plays a crucial legal and safety role as a witness and consent verifier.

Nurse's Responsibilities in Consent Verification

1. Verification of Signature and Voluntariness: The nurse verifies that the patient (or legal surrogate) signed the official consent form voluntarily, without coercion, while fully conscious and competent.
2. Validation of Patient Understanding: The nurse assesses whether the patient understands the nature of the scheduled operation, the surgical site, expected benefits, inherent risks, and alternatives. If the patient expresses severe confusion, misunderstanding, or revocation of consent, the nurse must immediately notify the operating surgeon and delay preoperative sedation or transfer to OT.
3. Witnessing Legal Documentation: The nurse's signature on the consent document certifies that the patient signed in the nurse's presence and appeared mentally competent at the time of signing. It does not imply that the nurse delivered the medical explanation of surgical risks.
4. Special Considerations under the Mental Capacity Act (MCA Cap. 177A): If an adult patient lacks decision-making capacity due to severe cognitive impairment, legal consent must be verified via a valid Donee under a Lasting Power of Attorney (LPA) with Personal Welfare powers or a court-appointed Deputy. In emergency life-threatening scenarios where no surrogate is available, the operating surgeon may proceed under the doctrine of necessity, documented thoroughly in the medical records.

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Risk Stratification & Preoperative Checklist Integration

Preoperative preparation culminates in standard clinical risk scoring and checklist verification.

Clinical Scenario: Preoperative Verification in Action

A 68-year-old male with type 2 diabetes mellitus and hypertension is scheduled for elective laparoscopic cholecystectomy at 08:00 at a Singapore general hospital. During the 06:30 preoperative nursing assessment, the nurse notes that the patient took his morning dose of Metformin and Aspirin with a full glass of milk at 05:30 because he felt anxious.

Nursing Action: The nurse immediately recognizes two critical preoperative breaches: milk intake within 2 hours of surgery violating the 6-hour non-clear fluid fasting rule, and ingestion of a withheld oral hypoglycaemic. The nurse immediately:

1. Holds further preoperative transport and notifies the operating surgeon and anesthetist.
2. Performs an immediate Capillary Blood Glucose (CBG) test and records baseline vital signs.
3. Documents the exact timing and nature of fluid/medication intake.
4. Re-evaluates surgical timing with the OT coordinator (delaying the case to allow adequate gastric emptying time).