IV Fluids

A) Crystalloid solutions (< 30 000 Dalton):

1-Hypotonic solutions:

- D₅W, ½ NS, D5 ¼ NS, D5 ½ NS.

2-Isotonic solutions:

- NS, Ringer’s, Lactated Ringer’s (Hartmann’s), Ringer’s acetate.

3-Hypertonic solutions:

- NaCl (3%, 7.5%), Mannitol (10%, 20%), NaHCO₃ (5%, 7.5%, 8.4%).

B) Colloid solutions (> 30 000 Dalton):

1-Blood derived:

- Human albumin (5%, 25%).

- Plasma protein fraction 5%.

2-Synthetic:

a) Dextrose Starches:

- They are D-glucose polymers linked by alpha bonds into linear macromolecules prepared from sucrose.

- Their half-life is 12 hours.

- 6% Dextran-70 (Macrodex) MW = 70 000 Dalton

- 10% Dextran-40 (Rheomacrodex) MW = 40 000 Dalton

- Dextran-1 (Promit).

- Dose: 20 ml/kg/d., Max.: 1.5 L/d.

Disadvantages:

- Interfere with blood typing.

- Antiplatelet effect.

- Antigenic effect with anaphylactoid and anaphylactic reactions.

- Affects renal functions and can be associated with renal failure.

b) Gelatins:

- Their M.W. 30 000-35 000 Dalton.

- Their half-life is 4-5 hours.

- Succinylated Gelatin (Gelofusine 3.5%, 4%).

- Polygelline (Hemaccel 3.5%, Hemagel 4%).

- Dose: 20 ml/kg/d., Max.: 1.5 L/d.

Advantages:

- Does not interfere with blood grouping.

- Does not affect renal function.

Disadvantages:

- Histamine-mediated allergic reaction.

c) Hydroxy-Ethyl Starch (HES) (Etherified Starch):

Synthetic colloids resemble glycogen structurally, synthesized from amylopectin.

- Heta-starch (Hexa-starch) (e.g. HAES-Steril, Hespan): M.W. 450 000 Dalton, half-life 48 hours.

- Hextend: M.W. is higher, and the half-life is longer.

- Penta-starch: M.W. 200 000, half-life less than 24 hours.

- Tetra-starch: (e.g. Tetraspan, Voluven): M.W. 130 000, half-life less than 6 hours.

- Dose: 20-50 ml/kg/d.

Advantages:

- Do not affect the coagulation study.

- Not antigenic but can cause anaphylactoid reactions.

- Less expensive than human albumin.

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Charcot-Marie-Tooth Disease

Charcot-Marie-Tooth Disease (CMT)

-Charcot-Marie-Tooth disease (CMT) is a neuromuscular disorder characterized by length-dependent degeneration of the motor and sensory nerve fibers, with a prevalence of 1 in 2,500 (about 200,000 patients in the European Union).

-Anesthesia is administered to this population more frequently than to normal people, as CMT patients often need orthopedic surgery to correct muscle imbalance and limb deformities, and for osteosynthesis of bone fractures as they are prone to falls.

Anesthetic Management Complications:

1-Malignant hyperthermia.

2-Prolonged responses to neuromuscular blocking drugs.

3-Drug toxicity is caused by inappropriate doses in case of severe muscle wasting.

4-Medication-induced exacerbation of neuropathy.

5-Associated deformities such as scoliosis.

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 Ventilators

-Early ventilators consisted of the generation of negative pressure around the whole of the patient’s body except the head and neck; these were called Cabinet or Iron lung ventilators.

-A negative pressure could also be applied over the thorax and abdomen: Cuirass Ventilators.

Classification:

1. Pattern of gas flow during inspiration:

a) Pressure generators:

Constant pressure is produced by bellows or a moderate weight which produces a decreasing inspiratory flow that alters with changes in lung compliance

b) Flow generators:

Constant flow is produced by a piston, heavyweight, or compressed gas. Flow is unaltered by changes in lung compliance although pressures will vary. These ventilators have a high internal resistance to protect the patient from high working pressures.

2. Power:

Pressure generators are low powered whereas flow generators are high powered.

3. Cycling:

Change from inspiration to expiration may be determined by:

a) Time:

The most common method. The duration of inspiration is predetermined, with the constant flow it may be necessary to preset a TV; when this has been delivered there is an inspiratory pause (improves distribution) before the inspiratory cycle ends.

b) Pressure:

Used as a pressure limit on other modes. The ventilator cycles into expiration when preset airway pressure is reached (delivers a different TV if compliance or resistance changes). Inspiratory time varies according to compliance and resistance.

c) Volume:

Usually used with an inspiratory flow restrictor. Cycles into expiration whenever a preset TV is reached.

d) Flow:

Older ventilators.

4. Sophistication:

Newer ventilators can function in many of the above-mentioned modes and have also weaning modes such as SIMV, PS, and CPAP.

5. Function:

a) Minute volume dividers:

Fresh gas flow powers the ventilator. Minute volume equals the FGF divided into pre-set tidal volumes, thus determining the frequency.

b) Bag squeezers:

Replaces the hand ventilation of a Mapleson D or circle system. It needs an external power source.

c) Lightweight portable:

Powered by compressed gas and consists of the control unit and patient valve.

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