12.2 Geriatric Critical Care & Patients with Specialized Medical Technology

12.2 Geriatric Critical Care & Patients with Specialized Medical Technology

Clinical Overview: The management of geriatric patients and individuals dependent on complex home medical technologies represents a sophisticated realm of critical care transport. Aging alters baseline physiology and blunts classic signs of shock, while mechanical device failures present acute life-threatening emergencies requiring targeted troubleshooting protocols.

Physiological Changes of Aging & Clinical Assessment

Aging causes progressive structural and functional decline across all major physiological systems, impairing homeostatic reserve and altering responses to stress, trauma, and disease.

Cardiovascular Aging & Blunted Shock Response

• Decreased Cardiac Reserve: Age-related arterial stiffening, left ventricular hypertrophy, and reduced myocardial compliance impair diastolic filling. Resting cardiac output declines, and maximum achievable heart rate drops significantly ($HR_{max} \approx 220 - \text{age}$).
• Blunted Autonomic Response: Down-regulation of beta-adrenergic receptors blunts the sympathetic nervous system response to stress, hypovolemia, and hypoxia.
• Medication Masking: Widespread use of beta-blockers, non-dihydropyridine calcium channel blockers, and antiarrhythmics prevents compensatory tachycardia during hemorrhagic or septic shock. A geriatric trauma patient with a "normal" heart rate of 80 bpm and BP of 115/75 mmHg may actually be in profound decompensated shock.
• Baseline Hypertension & Relative Hypotension: Elderly patients often have baseline systolic blood pressures of 150–160 mmHg. A systolic pressure of 100 mmHg in a chronically hypertensive geriatric patient represents severe relative hypotension and organ hypoperfusion.

Renal Function & Pharmacokinetics

• Glomerular Filtration Rate (GFR) Decline: Renal mass decreases by 20% to 30% with aging, and renal blood flow decreases by approximately 10% per decade after age 40.
• Creatinine Clearance Calculation: Serum creatinine alone is an unreliable indicator of renal function in elderly patients due to reduced muscle mass. Paramedics must calculate Creatinine Clearance ($CrCl$) using the Cockcroft-Gault formula:

$CrCl\text{ (mL/min)} = \frac{(140 - \text{Age}) \times \text{Weight (kg)}}{72 \times \text{Serum Creatinine (mg/dL)}} \quad [\times 0.85\text{ for females}]$

• Drug Accumulation & Toxicity: Decreased $CrCl$ delays clearance of renally eliminated drugs (e.g., Digoxin, Low-Molecular-Weight Heparins, Aminoglycosides, Vecuronium active metabolites). Hydrophilic volume of distribution decreases, while fat mass increases, prolonging the elimination half-life of lipophilic sedatives like Diazepam and Midazolam.

Integumentary, Vascular, & Musculoskeletal Fragility

• Vascular Fragility: Thinning of blood vessel walls and loss of subcutaneous fat make peripheral intravenous access difficult and increase the risk of severe subcutaneous hematomas and shearing injuries during patient movement.
• Cervical Spine Vulnerability: Degenerative disc disease, osteophytes, and ankylosing spondylitis make the geriatric cervical spine exceptionally vulnerable to hyperextension injuries. Minor mechanism falls (e.g., fall from standing) can produce central cord syndrome or unstable odontoid fractures.

Patients with Specialized Medical Technology

Transport paramedics frequently encounter patients dependent on complex, surgically implanted or home-based life-support technologies. Transport success requires immediate identification of device mechanics, alarm interpretations, and acute failure management.

Left Ventricular Assist Devices (LVAD)

Continuous-flow LVADs (e.g., HeartMate 3, HVAD) pull blood from the left ventricle and pump it continuously into the ascending aorta.

• Pulseless Physiology: Continuous flow results in a minimal or absent pulse, non-palpable peripheral pulses, and unmeasurable standard automated non-invasive blood pressure (NIBP) or pulse oximetry.
• Blood Pressure Assessment: Mean Arterial Pressure (MAP) must be determined using a manual blood pressure cuff and a Doppler ultrasound probe placed over the brachial or radial artery. Inflate the cuff until Doppler flow sounds cease, then deflate slowly; the pressure at which continuous arterial flow sounds return represents the Doppler MAP (Target MAP: 70 to 90 mmHg).
• LVAD Alarms & Failure: Common causes of alarms include hypovolemia (suction events), driveline damage, pump thrombosis, right ventricular failure, and battery depletion.
• Resuscitation Rules:
  1. Do NOT perform CPR / chest compressions on an LVAD patient unless explicitly authorized by the regional VAD center or if the pump has completely stopped and cannot be restarted, as chest compressions risk catastrophic ventricular cannula dislodgement and cardiac rupture.
  2. Perform immediate assessment of device power source, replace depleted batteries/controller, check driveline connection, assess fluid status (administer IV fluid boluses for low flow/suction alarms), and contact the VAD coordinator listed on the patient's controller immediately.

Specialized Medical Technology Emergency Matrix

Tracheostomies & Emergency Airway Management

• Troubleshooting (DOPE Protocol):
  • Dislodgement: Check tube placement and depth.
  • Obstruction: Mucus plug or blood clot.
  • Pneumothorax: Assess breath sounds and chest rise.
  • Equipment failure: Check ventilator circuit and inner cannula.
• Cannula Obstruction Protocol:
  1. Administer 100% $FiO_2$.
  2. Remove and inspect the inner cannula; clean or replace immediately if occluded.
  3. If obstruction persists, pass a flexible suction catheter pre-measured to the length of the tracheostomy tube. Instill 2–3 mL of sterile normal saline if mucus is tenacious.
• Accidental Decannulation Protocol:
  • Mature Tract ($> 7$ days post-op): Lubricate an equivalent-sized or one-size-smaller tracheostomy tube, insert using the internal obturator, immediately remove obturator, confirm placement with capnography, and secure.
  • Immature Tract ($< 7$ days post-op): High risk of creating a false lumen in subcutaneous tissue. If re-entry fails or tract is immature, cover the stoma with a sterile occlusive dressing and ventilate the upper airway via bag-valve-mask (or ventilate directly over stoma with a pediatric mask if upper airway is surgically occluded).

Home Mechanical Ventilators & Enteral Tubes

• Home Ventilators: Transport crews should transition home vent patients to transport ventilators matching baseline settings (Mode, $V_T$, PEEP, $FiO_2$, I:E ratio) while maintaining external battery redundancy and dedicated suction equipment.
• Enteral Feeding Tubes (G-Tubes & J-Tubes):
  • Dislodgement: An established G-tube tract can close within 2 to 4 hours. To preserve tract patency during transport, insert a sterile Foley catheter of equivalent French size into the stoma, advance 2–3 cm, inflate balloon with 3–5 mL sterile water, and gently pull back to seal. Do NOT use the Foley catheter for feeding.
  • Clogging Management: Flush with 30–50 mL of warm water using a push-pull syringe motion. Never use forceful pressure or thin metal wires which risk tube rupture or visceral perforation.

Central Venous Catheters, Baclofen Pumps, & VP Shunts

• Central Venous Catheters (PICC, Hickman, Broviac):
  • Air Embolism Management: Sudden disconnection leads to air entrainment into central venous circulation. Immediately clamp the line, place patient in Left Lateral Decubitus Trendelenburg position (Durant's maneuver) to trap air in the right ventricular apex away from the pulmonary outflow tract, and administer 100% $FiO_2$.
• Intrathecal Baclofen Pumps:
  • Acute Withdrawal Crisis: Failure of the pump or catheter causes loss of GABA-B receptor stimulation within 6 to 12 hours. Symptoms include rebound severe spasticity, hyperthermia, rhabdomyolysis, seizures, disseminated intravascular coagulation (DIC), and multi-organ failure. Treatment: High-dose IV Benzodiazepines (e.g., Lorazepam, Diazepam), aggressive cooling, and urgent neurosurgical intervention.
• Ventriculoperitoneal (VP) Shunts:
  • Shunt Failure & Infection: Obstruction or infection of VP shunts presents with signs of elevated Intracranial Pressure (ICP): progressive severe headache, projectile vomiting, lethargy, altered mental status, papilledema, subgaleal fluid tracking along the shunt pathway, and Cushing's triad (bradycardia, hypertension, irregular respirations). Maintain head of bed at 30° and transport urgently for neurosurgical revision.