Investigation into Significant Anesthesia
Adverse Events during the Post-Op Period
Research by:Ryan Dietz RNAIStephen Both RNAI Gonzaga UniversityProvidence Sacred Heart Medical
CenterMarch 20, 2014
MethodologyRetrospective Chart Review
At PHSMCPopulations
1. Strokes, cardiopulmonary arrests (CPAs), and deaths
(within 30 days of an anesthetic)2. PACU physiologic instability
Hemodynamic problems Bleeding Oxygenation issues
Study numbers:Charts from 2013
PACU physiologic instability 29 Strokes 13 CPAs 16 Mortality 41 99
Number of Patients Investigated
(1 mo.)(6mo.)(6mo.)(6mo.)
~Inpatient Research Study~
Hypertension35%
Resp De-pression
30%
Hypotension20%
Arrhythmia 5%
Bleeding5%
Hyper-glycemia
5%Physiologic Instability PACU (n=29) PSHMC
Hypotension Dynamics
ASA I ASA II ASA III ASA IV ASA V0%
10%
20%
30%
40%
50%
60%
70%ASA Distribution (n=29)
PSHMC
Physiologic Instability (PACU)
Perc
ent
of P
atie
nts
68%16%
16%
ASA II Physiologic Instability Causes
PACU (n=13) PSHMC Hypotension
Resp de-pressionBleeding
44% of this group received Spinal Anesthesia
62%31%
8%
Stroke Etiology at PSHMC (n=13) PSHMC
Embolic
Ischemic
Hemorrhagic
Cardiac Vascular Ortho Neuro0%
20%
40%
60%
80%
100%
120%
40%50%
100%
0%
60%
25%
0%
100%
0%
25%
0% 0%
Surgery Type with Cor-responding Type of
Stroke (n=13) PSHMC
EmbolicIschemicHemorrhagic
Surgery Type
Perc
ent
of S
urge
ry T
ype
Determinants of Cerebral Blood Flow
Two Determinants of cerebral blood flow:1. Cerebral Vascular Resistance
PaCO2 PaO2 Metabolism
2. Cerebral Perfusion Pressure (CPP) Blood Pressure ICP
1 2 3 4 5 6 7 8 9 10 11 12 130
20406080
100120140160180
Stroke: Systolic Comparison SAU vs Entrap (n=13) PSHMC
SAU SBPIntraop SBP
Patients that Experienced a Stroke
BP S
ysto
lic
EMBOLIC STROKES
PaCO2
39.4-42.6
44.2-49.6
28.8-33.2
J. of Cerebral Blood Flow, (2003) : 23 (6). 665-670 [15]
Detrimental Effect of Hypocapnia
Hypocapnia[1,2,3,8,9]
Directly neurotoxic↑ neuronal excitability
while ↓ cerebral O2 supply
↓ V/Q matchingCauses lung injury via inflammation activation
Increase risk of infection
Undermines respiratory drive postop
↓myocardial O2 supply ST depression syndrome
↓ SvO2 Prolongs wakeups↑Pain in postop
54%
23%
15% 8%
etCO2 Values Among Stroke Cases (n=13)
PSHMC
25-3030-3535-4040-45
Summary of Findings1. Hypertension was the #1 cause
of physiologic instability in the PACU
2. 44% of ASA II patients that experienced hypotension also received spinals
3. 54% of patients that experienced strokes during the post op period had etCO2 levels maintained between 25-30 mmHg
Hypertension RecommendationsClinical Situation Drug of ChoicePain AnalgesicHypertension without cardiac complications
HydralazinePhentolamineNifedipineNicardipine
Severe acute hypertension Sodium Nitroprusside
Hypertension plus ischemia Nitroglycerine infusion
Hypertension plus tachycardia and ischemia
Esmolol, bolus or infusion
Hypertension plus heart failure Ace Inhibitor, dobutamine
Hypertension caused by pheochromocytoma
Phentolamine, LabetalolDoxazosin, prazosin, terazocin
Continuing Education in Anaesthesia, Critical Care & Pain. (2004) 4 (5): 139-143 [10] Miller’s Anesthesia (2010) p.1094-1095 [21]
Hypotension
Airway Intact?
Effective ventilation & oxygenation?
Appropriate ECG rate, rhythm, and morphology?
Consider hypovolemia,
administer NS IV Bolus
Consider Other etiologies:1. Surgical complications 7. Medication 2. Bleeding 8. Anaphylaxis3. Residual general 9. Equipment Malfunction4. Sepsis5. Anesthesia 6. Sympathectomy from regional blk
Journal of PeriAnesthesia Nursing. (2002). 17 (3) 159-163. [7]
Hypotension Algorithm
Spinal Hypotension A) Blockade of sympathetic efferents (arterial and venodilation)
B) Potential for cardiac accelerator suppression (T1-T4)
Treatment[5]
1. Crystalloid: (500-1500ml ) pretreatment better than co-treatment 2. Colloid: superior to crystalloid (↑SVR) (30 min half-life) Hespan= $12.04/500ml bag *3. Ephedrine superior to Phenylephrine (caution tachyphylaxis)4. Dopamine short term upon ephedrine tachyphylaxis onset5. Cautious use of phenylephrine in the elderly: with reports of ↓
C.O. and LV dysfunction
* Cost at PSHMC /Tony Hill (Materials Management Manager PSHMC)
Mechanism[5]
Hypercapnia1. Benign (paCO2≤70)
[1]
2. Enhances respiratory drive [9]
3. Protects lung tissues [14]
4. Advance warning of inadequate analgesia and relaxation [1]
5. ↑in PaCO2 by 10mmHG
↑the C.I. by about 10-15% [17]
6. ↓ SVR, ↑SvO2 [17]
7. 3-5% alteration in CBF for every 1 mmHg change in PaCO2 [2]
8. Decrease in infection postop [2,3,34]
9. Avoid hypercapnia and hypocapnia in known cerebral ischemic patients [21]
Mild Respiratory Acidosis (A good Thing?)
Hypercapnia can, and many times will lead to mild respiratory acidosis [14,28]
Respiratory Acidosis is different than metabolic acidosis (slight sympathetic activation) [17]
1. ↑ Inotropy2. ↓ SVR3. ↑ Blood pressure4. ↑ HR
PH of 7.15 is tolerated before buffering agents/ ↑RR are necessary [14,28]
“I’m pretty comfortable with a low pH threshold of 7.17 in the healthy or appropriate respiratory acidosis patient” Dr. Chris Vernon DO (Intensivist PSHMC )
Elevated ICP RecommendationsHypocapnia:
Should only be utilized in two instances[13]
1. Impending brain herniation2. To increase surgical field of view
Normal goal in head injury or elevated ICP is a PaCO2=35-40 [13]
Hypocapnia is only viable for 20 minutes due to cerebral ischemia [13]
Treating impending herniation with hyperventilation [6,21,30]
Goal of PaCO2=30-32Strictly avoid PaCO2 levels below 25 mm HGNot to be used for >20 minutes
Recommendations: Stroke Group
1. Delay elective surgery at least 6 weeks after stroke [21]
2. Continue anticoagulation for minor surgeries (esp. afib + prior stroke) [25]
3. Continue low dose aspirin in patients under procedures of high risk for bleeding and stroke (Bridge with heparin for pt with afib and Hx of Tia/Stroke) [25]
4. Continue beta blockers and statins preop and restart postop [25]
5. Metoprolol controversial during the case (3-4 fold ↑ in strokes). Esmolol & Labetalol, Bisoprolol better choices [4,19,27]
Recommendations: Stroke Group6. Regional is only beneficial in orthopedic cases
[20,25]
7. Avoid hyperventilation during surgery: theories such as “Inverse steal” and “Robin Hood” actually increase the region at risk for stroke [22,29,33]
8. Recommended goal of PCO2 should be normocapnia (35-45). Avoid hypo and hypercapnia in potential cerebral ischemia cases [24]
9. Hypo-albuminemia is a predictor of stroke risk [12]
10.Maintain glucose 60-150mg/dl [11,16]
ConclusionThe purpose of this research project was to
identify potential themes in patient comorbidities, surgery type, and anesthetic management that may potentially contribute to significant postop complications.
Although we did not uncover any “smoking gun” anesthesia related issues, we highlighted and made recommendations regarding 3 interesting findings. Anesthesia is a journey and we will need to continually re-evaluate the method in which we deliver anesthesia.
QUESTIONS?
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