4.2 Management of Patients with Cardiovascular, Respiratory & Renal Diseases

4.2 Management of Patients with Cardiovascular, Respiratory & Renal Diseases

Treating medically compromised patients requires thorough pre-operative risk assessment, tailored dental management strategies, and an understanding of systemic drug interactions. Dental practitioners must evaluate organ reserve, modify treatment parameters (such as appointment duration, patient positioning, and local anaesthetic selection), and recognize when elective dental treatment must be deferred.

---

Cardiovascular Diseases in Dental Practice

Cardiovascular conditions represent the most prevalent medical complexity encountered in adult dental populations. Stress management protocols and vasoconstrictor limits are central to safe care.

Hypertension Classification & Dental Cut-Off Guidelines

Ischaemic Heart Disease (IHD)

• Stable Angina: Chest pain predictably induced by exertion and relieved by rest or sublingual GTN. Protocol: Short morning appointments, stress reduction, keep GTN spray on the dental bracket table. Vasoconstrictor cap: Max 0.04 mg adrenaline (approx. 2 cartridges of 1:100,000 adrenaline).
• Unstable Angina / Recent Myocardial Infarction (<6 months): High risk for re-infarction or fatal arrhythmia. Defer all elective dental care for a minimum of 6 months (or 3–6 months with cardiology clearance). Emergency treatment should be conservative and performed in a hospital dental facility if required.
• Drug Interaction Warning — Non-Selective Beta-Blockers: Patients taking non-selective beta-blockers (e.g., Propranolol) experience unopposed $\alpha_1$-adrenergic vasoconstriction when exogenous adrenaline is administered, precipitating acute severe hypertension accompanied by compensatory reflex bradycardia. Limit adrenaline strictly to $\le 0.04\text{ mg}$ or use Prilocaine with Felypressin / Mepivacaine Plain.

Heart Failure & New York Heart Association (NYHA) Staging

• NYHA Class I / II: Mild dyspnoea on heavy exertion. Routine care with stress reduction.
• NYHA Class III / IV: Dyspnoea on minimal exertion or at rest. Intolerant of supine position (orthopnea and paroxysmal nocturnal dyspnoea). Treatment Protocol: Seat patient in an upright or semi-recumbent position; avoid fluid overload during ultrasonic scaling; cap adrenaline at 0.04 mg.
• Cardiac Pacemakers & Implantable Cardioverter-Defibrillators (ICDs): Modern bipolar pacemakers and ICDs are well-shielded against electromagnetic interference (EMI). Contemporary piezo-electric ultrasonic scalers and curing lights are safe, though older unshielded magnetostrictive units should be kept at least 30 cm away from the cardiac generator.

---

Respiratory Diseases

Respiratory compromise impairs oxygen delivery and hypercapnic clearance, influencing local anaesthetic and sedative selection.

Asthma Management in Dentistry

• Pre-operative Assessment: Identify frequency of attacks, hospitalisations, and triggers (cold air, anxiety, allergens, exercise).
• Pharmacological Hazards:
  1. NSAIDs & Aspirin: Contraindicated in patients with Aspirin-Exacerbated Respiratory Disease (AERD / Samter's Triad). NSAIDs cause COX-1 inhibition, shunting arachidonic acid into the 5-lipoxygenase pathway and triggering severe leukotriene-mediated bronchospasm.
  2. Sodium Metabisulfite: Preservative in adrenaline-containing local anaesthetics; can trigger asthmatic reactions in sulfite-sensitive patients.
  3. Macrolides & Theophylline: Erythromycin and Clarithromycin inhibit hepatic CYP1A2, elevating plasma Theophylline to toxic levels (arrhythmias, seizures).
• Protocol: Instruct patients to bring their rescue bronchodilator (Salbutamol) to every appointment. Pre-treatment inhalation of 2 puffs of Salbutamol prior to invasive procedures prevents stress-induced bronchospasm.

Chronic Obstructive Pulmonary Disease (COPD)

COPD comprises chronic bronchitis and emphysema, resulting in irreversible airway obstruction.

• Pathophysiology of Hypoxic Drive: Long-standing hypercapnia (high $PaCO_2$) desensitises central chemoreceptors. Breathing becomes driven by peripheral chemoreceptors responsive to hypoxia ($PaO_2$). Administering high-flow oxygen (>2–3 L/min) abolishes this hypoxic drive, causing severe respiratory depression and carbon dioxide narcosis.
• Dental Management Parameters:
  • Seat patient upright or semi-recumbent to optimize diaphragmatic excursion.
  • Avoid rubber dam if it exacerbates feelings of suffocation.
  • Avoid central nervous system depressants (opioids, benzodiazepines, barbiturates).
  • Nitrous oxide inhalation sedation is relatively contraindicated in severe bullous emphysema due to expansion of air spaces.

---

Renal Disease & End-Stage Renal Disease (ESRD)

Chronic Kidney Disease (CKD) impairs excretion of metabolic waste and drugs, alters haemostasis, and requires specific scheduling around renal replacement therapy.

+---------------------------------------------------------------------------------------------------+
|                                 CKD STAGING BY eGFR (mL/min/1.73m²)                               |
|                                                                                                   |
|  Stage 1: Normal (eGFR ≥90)          =======>  Standard Dental Care                               |
|  Stage 2: Mild (eGFR 60-89)          =======>  Standard Care; monitor drug dosing                 |
|  Stage 3: Moderate (eGFR 30-59)      =======>  Dose adjustment for renally cleared drugs          |
|  Stage 4: Severe (eGFR 15-29)        =======>  AVOID NSAIDs; consult nephrologist                 |
|  Stage 5: Failure / ESRD (eGFR <15)  =======>  Dialysis timing protocol; extreme bleeding risk   |
+---------------------------------------------------------------------------------------------------+

Pathophysiological Sequelae of ESRD

1. Uremic Bleeding Diathesis: Accumulation of uremic toxins impairs platelet adhesion and aggregation (dysfunctional von Willebrand factor binding to platelet glycoprotein IIb/IIIa receptors), causing prolonged bleeding times despite a normal platelet count.
2. Renal Osteodystrophy: Hyperphosphatemia and hypocalcemia trigger secondary hyperparathyroidism, producing widespread bone resorption, loss of lamina dura, and brown tumours of the jaws.
3. Renal Anemia: Decreased erythropoietin production by juxtaglomerular cells leads to normocytic normochromic anemia, impairing tissue healing.

Haemodialysis Dental Management Protocol

• Appointment Timing (CRITICAL): Perform elective dental treatment on the DAY AFTER haemodialysis (e.g., Tuesday or Thursday for a Mon/Wed/Fri dialysis regimen).
  • Rationale: On the day of dialysis, the patient receives systemic Heparin (high bleeding risk) and suffers metabolic fatigue. On the day after, circulating heparin has cleared (half-life ~1–2 hours), fluid and electrolyte balances are optimal, and uremic toxins are minimal.
• Arteriovenous (AV) Fistula Protection: NEVER take blood pressure measurements or place intravenous lines on the arm containing an AV fistula or graft, as pressure can cause thrombosis and permanent shunt failure.
• Nephrotoxic Drug Avoidance: NSAIDs (Ibuprofen, Naproxen, Ketorolac) are strictly contraindicated in severe renal impairment (eGFR $<30 ext{ mL/min}$) as they cause acute tubular necrosis and inhibit renal prostaglandin-mediated perfusion.