486 Section II / General Surgery

What is the primary use of the PCWP?

Has the usage of a SwanGanz catheter been shown to decrease mortality in ICU patients?

As an indirect measure of preload intravascular volume

NO

MECHANICAL VENTILATION

Define ventilation.

Define oxygenation.

What can increase ventilation to decrease PCO2?

What is minute ventilation?

Define tidal volume.

Are ventilation and oxygenation related?

What can increase PO2 (oxygenation) in the ventilated patient?

What can decrease PCO2 in the ventilated patient?

Define the following modes: IMV

Air through the lungs; monitored by

PCO2

Oxygen delivery to the alveoli; monitored by O2 sats and PO2

Increased respiratory rate (RR), increased tidal volume (minute ventilation)

Volume of gas ventilated through the lungs (RR tidal volume)

Volume delivered with each breath; should be 6 to 8 cc/kg on the ventilator

Basically no; you can have an O2 sat of 100% and a PCO2 of 150; O2 sats do not tell you anything about the PCO2 (key point!)

Increased FiO2

Increased PEEP

Increased RR

Increased tidal volume (i.e., increase minute ventilation)

Intermittent Mandatory Ventilation: mode with intermittent mandatory ventilations at a predetermined rate; patients can also breathe on their own above the mandatory rate without help from the ventilator

	Chapter 65 / Surgical Intensive Care 487
SIMV	Synchronous IMV: mode of IMV
	that delivers the mandatory breath
	synchronously with patient’s initiated
	effort; if no breath is initiated, the
	ventilator delivers the predetermined
	mandatory breath
A-C	Assist-Control ventilation: mode in which
	the ventilator delivers a breath when
	the patient initiates a breath, or the
	ventilator “assists” the patient to breathe;
	if the patient does not initiate a breath,
	the ventilator takes “control” and deliv-
	ers a breath at a predetermined rate
	In contrast to IMV, all breaths are by the
	ventilator
CPAP	Continuous Positive Airway Pressure:
	positive pressure delivered continu-
	ously (during expiration and inspira-
	tion) by ventilator, but no volume
	breaths (patient breathes on own)
Pressure support	Pressure is delivered only with an
	initiated breath; pressure support
	decreases the work of breathing by
	overcoming the resistance in the
	ventilator circuit
APRV	Airway Pressure Release Ventilation:
	high airway pressure intermittently
	released to a low airway pressure
	(shorter period of time)

HFV

What are the effects of positive pressure ventilation in a patient with hypovolemia or low lung compliance?

High Frequency Ventilation: rapid rates of ventilation with small tidal volumes

Venous return and cardiac output are decreased

Define PEEP.	Positive End Expiration Pressure:
	positive pressure maintained at the end
	of a breath; keeps alveoli open

488 Section II / General Surgery

What is “physiologic PEEP”? PEEP of 5 cm H2O; thought to approximate normal pressure in normal nonintubated people caused by the closed glottis

What are the side effects of increasing levels of PEEP?

What are the typical initial ventilator settings:

Mode?

Tidal volume?

Ventilator rate?

FiO2?

PEEP?

Barotrauma (injury to airway pneumothorax), decreased CO from decreased preload

Intermittent mandatory ventilation

6–8 ml/kg

10 breaths/min

100% and wean down

5 cm H2O

From these parameters, change according to blood-gas analysis

What is a normal I:E (inspiratory to expiratory time)?

When would you use an inverse I:E ratio (e.g., 2:1, 3:1, etc.)?

When would you use a prolonged I:E ratio (e.g., 1:4)?

What clinical situations cause increased airway resistance?

What are the presumed advantages of PEEP?

1:2

To allow for longer inspiration in patients with poor compliance, to allow for “alveolar recruitment”

COPD, to allow time for complete exhalation (prevents “breath stacking”)

Airway or endotracheal tube obstruction, bronchospasm, ARDS, mucous plug, CHF (pulmonary edema)

Prevention of alveolar collapse and atelectasis, improved gas exchange, increased pulmonary compliance, decreased shunt fraction

What are the possible	Decreased cardiac output, especially in
disadvantages of PEEP?	the setting of hypovolemia; decreased gas
	exchange; T compliance with high levels
	of PEEP, fluid retention, increased
	intracranial pressure, barotrauma

What parameters must be evaluated in deciding if a patient is ready to be extubated?

Chapter 66 / Vascular Surgery 489

Patient alert and able to protect airway, gas exchange (PaO2 70, PaCO2 50), tidal volume ( 5 cc/kg), minute ventilation ( 10 L/min), negative inspiratory pressure ( 20 cm H2O, or more negative), FiO2 40%, PEEP 5, PH 7.25, RR 35, Tobin index 105

What is the Rapid-Shallow Breathing (a.k.a. Tobin) index?

What is a possible source of fever in a patient with an NG or nasal endotracheal tube?

Rate: Tidal volume ratio; Tobin index105 is associated with successful extubation (Think: Respiratory TherapistRT Rate: Tidal volume)

Sinusitis (diagnosed by sinus films/CT)

What is the 35 45 rule of	Normal values:
blood gas values?	pH 7.35 7.45
	PCO2 35 45
Which medications can be	Think “NAVEL”:
delivered via an	Narcan
endotracheal tube?	Atropine
	Vasopressin
	Epinephrine
	Lidocaine
What conditions should you	1. Tension pneumothorax
think of with c peak airway	2. Abdominal compartment syndrome
pressure and T urine
output?

C h a p t e r 66	Vascular Surgery
What is atherosclerosis?	Diffuse disease process in arteries;
	atheromas containing cholesterol and
	lipid form within the intima and inner
	media, often accompanied by ulcerations
	and smooth muscle hyperplasia

490 Section II / General Surgery

What is the common theory of how atherosclerosis is initiated?

What are the risk factors for atherosclerosis?

Endothelial injury S platelets adhere S growth factors released S smooth muscle hyperplasia/plaque deposition

Hypertension, smoking, diabetes mellitus, family history, hypercholesterolemia, high LDL, obesity, and sedentary lifestyle

What are the common sites of plaque formation in arteries?

What must be present for a successful arterial bypass operation?

Branch points (carotid bifurcation), tethered sites (superficial femoral artery [SFA] in Hunter’s canal in the leg)

1.Inflow (e.g., patent aorta)

2.Outflow (e.g., open distal popliteal artery)

3.Run off (e.g., patent trifurcation vessels down to the foot)

What is the major principle of safe vascular surgery?

What does it mean to “POTTS” a vessel?

What is the suture needle orientation through graft versus diseased artery in a graft to artery anastomosis?

What are the three layers of an artery?

Which arteries supply the blood vessel itself?

What is a true aneurysm?

What is a false aneurysm (a.k.a pseudoaneurysm)?

Get proximal and distal control of the vessel to be worked on!

Place a vessel loop twice around a vessel so that if you put tension on the vessel loop, it will occlude the vessel

Needle “in-to-out” of the lumen in diseased artery to help tack down the plaque and the needle “out-to-in” on the graft

1.Intima

2.Media

3.Adventitia

Vaso vasorum

Dilation ( 2 nL diameter) of all three layers of a vessel

Dilation of artery not involving all three layers (e.g., hematoma with fibrous covering)

Often connects with vessel lumen and blood swirls inside the false aneurysm