Patient Safety Tip of the Week
December 6, 2016
Postoperative Pulmonary Complications
Postoperative
pulmonary complications are associated with increased morbidity and mortality,
prolonged hospital stays, and increased costs. A few recent studies have
demonstrated that these are common, sometimes may go undetected, and even the
milder ones have clinically significant implications.
One recent study (Fernandez-Bustamante
2016) notes that postoperative
pulmonary complications are heterogeneous in their pathophysiology, severity,
and reporting accuracy. The researchers performed a multicenter prospective observational
study in 7 US academic institutions of patients with ASA physical status of 3
who had noncardiothoracic surgery requiring 2 hours
or more of general anesthesia with mechanical ventilation. This included 1202
patients who underwent predominantly abdominal, orthopedic, and neurological
procedures. At least 1 postoperative pulmonary complication occurred in 33.4%
of patients. This included the need for prolonged oxygen therapy by nasal
cannula (19.6%) and atelectasis (17.1%). Patients with 1 or more postoperative
pulmonary complications, even mild, had significantly increased early
postoperative mortality, intensive care unit (ICU) admission, and ICU/hospital
length of stay. The authors conclude that mild frequent postoperative pulmonary
complications (eg, atelectasis and prolonged oxygen
therapy need) deserve increased attention and intervention for improving
perioperative outcomes.
Another study (Sun
2015) assessed oxygen saturation continuously, in a manner that was blinded
to clinicians, in patients who had undergone noncardiac
surgery. Those authors noted that on a typical post-op ward vital signs are
recorded at 4-6 hour intervals, including oxygen saturations that are measured
on a spot basis with pulse oximeters. Moreover, they also note that nurses
often respond to poor saturation values by encouraging patients to breathe
deeply until a near-normal saturation value is obtained and then record that
value in the medical record. Their study found that that prolonged hypoxemic
episodes were common. 37% of patients had at least one episode of oxygen
saturation <90% lasting an hour or more and that nurses missed 90% of
hypoxemic episodes detected by the blinded continuous monitoring in which
oxygen saturation was <90% for at least one hour.
Weve also noted in our numerous columns on obstructive
sleep apnea (OSA) that patients who have hypoventilation when sleeping often
have normal ventilation and normal oxygen saturation when aroused, such as when
nursing records vital signs. So they often have normal oxygen saturations
recorded in the medical record.
The Sun study does note that continuous monitoring of
oxygenation was difficult. They used a system that was somewhat bulky and mounted
on an IV pole and this significantly limited patient ambulation, causing many
patients to discontinue the monitors. This may have led to an overestimation of
hypoxemic events, as healthier patients may have disconnected them and
ambulated early. Newer wrist-mounted systems that communicate wirelessly with
hospital monitoring systems may alleviate this.
In an accompanying editorial, Robert Stoelting
from the Anesthesia Patient Safety Foundation (Stoelting
2015) notes that the APSF recommends that all post-op patients
receiving opioids be monitored with continuous pulse oximetry with data transmitted
wirelessly to a qualified health care professional. APSF also recommends
monitoring of ventilation if supplemental oxygen is needed to maintain an
acceptable SpO2.
The message is clear: the risk of hypoxemia post-operatively
is not confined to those patients we already knew were at high risk (such as
patients with known or suspected OSA). In fact, there is even one study (Khanna 2016) which
showed that the STOP-Bang questionnaire (which predicts the presence of OSA and
also predicts postoperative complications) does not predict hypoxemia in adults
recovering from noncardiac surgery. So there really
is a need for continuous monitoring in most postoperative patients.
A recent investigative report Dead in Bed by On Your Side
News 5 (Cleveland, Ohio) brought to public attention the problem of fatal
complications in postoperative patients considered at low-risk (Regan
2016). It described several cases of fatalities related to opioid-induced
respiratory depression in patients following surgery. It highlighted two root
causes: (1) aggressive pain management by hospitals to achieve better patient
satisfactions scores and (2) the substantial costs of implementing continuous
monitoring systems. Yet it noted that implementation of such monitoring
capabilities at Dartmouth-Hitchcock Medical Center (DHMC) was cost effective (AAMI
2013).
The Dartmouth-Hitchcock implementation resulted in
significantly fewer rescues (from 3.5 to 1.2 rescues per 1,000 patients) and
transfers to intensive care units (from 5.6 per to 2.9 per 1,000 patients).
They estimated a cost savings of roughly $1.5 million just from reduction in
ICU transfers (Taenzer
2012). DHMC subsequently implemented the continuous surveillance
monitoring system on all its units, with variable cost saving based upon the
underlying frequency of adverse events on each type of unit and the actual
reductions in ICU transfers. Generally, results were more positive on surgical
compared to medical units. And this was all accomplished with high levels of
both patient acceptance and acceptance by clinical staff. Read the two
documents (AAMI
2013, Taenzer 2012) to see the challenges and solutions the
DHMC staff found in implementing this system. They also describe how they set
parameters to be sensitive to clinically important deterioration yet avoiding
alarm fatigue.
Since so many pulmonary complications occur in post-op patients
who are receiving opioid therapy, we are always looking for ways to reduce the
impact of opioid therapy. Many have had the impression that such complications
are fewer when short-acting opioids are used compared to long-acting ones. So a
comparative study was done (Belcher
2016). Belcher and colleagues looked at patients on PCA pumps treated with
fentanyl (short-acting opioid) vs. morphine or hydromorphone (longer-acting
opioids) and found that the long-acting patient-controlled opioids were not associated with increased hypoxemia
during the first 2 postoperative days during which the study was done.
The best way to avoid opioid-induced respiratory depression
is obviously to avoid opioids or to use lower doses. Multimodal analgesia is
one of the best ways to accomplish this (see our February 19, 2013 Patient Safety Tip of the Week Practical
Postoperative Pain Management). That includes use of multiple non-opioid
analgesics with different modes of action (eg.
acetaminophen and an NSAID) plus local or regional nerve blocks. And, of
course, avoiding use of concomitant drugs that depress respiration (eg. benzodiazepines) is equally important.
Ironically, one of
the risk factors for some pulmonary complications is pain itself. It may impair
the ability to cough, thus predisposing patients to atelectasis or pneumonia.
Or pain may limit mobilization and early ambulation. In fact, the editorial (Haines
2016) accompanying the Fernandez-Bustamante study pointed out that the rate of
postoperative pulmonary complications was actually higher in the group who
underwent a combined anesthetic approach, including regional anesthesia. The
reason for that is not readily apparent. But the lesson is that we need to find
a happy medium between adequate management of pain and avoiding the respiratory
depressant effects of our pain management approaches.
Large percentages of
post-op patients also receive supplemental oxygen. While some (Hopf
2016) suggest even wider use of supplemental oxygen in this
population, we always caution that supplemental oxygen may delay recognition of
opioid-induced respiratory depression if one is not using capnographic
monitoring.
In our October 11,
2016 Patient Safety Tip of the Week New
Guideline on Preop Screening and Assessment for OSA
we noted that the Canadian Agency for Drugs and Technologies in Health (CADTH)
in 2016 did an analysis of end-tidal CO2 monitoring in the hospital setting (CADTH
2016). Though admitting that
high level evidence of efficacy is limited, they performed an exploratory
analysis which concluded that for patients in serious or critical condition and
for patients with obstructive sleep apnea or receiving high doses of opioids in
post-operative care, use of end-tidal CO2 monitoring is likely less costly and
more effective than standard monitoring.
Given the
significance of postop pulmonary complications it seems clear that
implementation of continuous monitoring systems is critical and that we cannot
just limit such to those patients who we suspect are at highest risk. The
limited literature available on cost effectiveness of such systems would
certainly suggest that these are investments well spent.
Other Patient Safety
Tips of the Week pertaining to opioid-induced respiratory depression and PCA
safety:
- January
4, 2011 Safer
Use of PCA
- July
13, 2010 Postoperative
Opioid-Induced Respiratory Depression
- May
12, 2009 Errors
With PCA Pumps
- September
21, 2010 Dilaudid
Dangers
- November
2010 More
on Preoperative Screening for Obstructive Sleep Apnea
- February 22, 2011 Rethinking
Alarms
- May 17, 2011 Opioid-Induced
Respiratory Depression Again!
- September 6, 2011 More
Tips on PCA Safety
- December 6, 2011 Why
You Need to Beware of Oxygen Therapy
- February
21, 2012 Improving
PCA Safety with Capnography
- September 2012 Joint
Commission Sentinel Event Alert on Opioids
- September 2012 FDA
Warning on Codeine Use in Children Following Tonsillectomy
- July 3, 2012 Recycling
an Old Column: Dilaudid Dangers
- February 12, 2013 CDPH:
Lessons Learned from PCA Incident
- February 19, 2013 Practical
Postoperative Pain Management
- May 6, 2014 Monitoring
for Opioid-induced Sedation and Respiratory Depression
- March 3, 2015 Factors
Related to Postoperative Respiratory Depression
- June 2, 2015 Reminders
of Dilaudid Dangers
- August 11, 2015 New
Oxygen Guidelines: Thoracic Society of Australia and NZ
- August 18, 2015 Missing
Obstructive Sleep Apnea
- December 2015 Opioid
Alert Fatigue
- March 2016 Guideline
for Management of Postoperative Pain
- June 14, 2016 Nursing
Monitoring of Patients on Opioids
- Tools:
PCA
Pump Audit Tool and the PCA
Pump Criteria
References:
Fernandez-Bustamante A, Frendl G,
Sprung J. Postoperative Pulmonary Complications, Early Mortality, and Hospital
Stay Following Noncardiothoracic Surgery. A
Multicenter Study by the Perioperative Research Network Investigators. JAMA Surg 2016; Published online November 9, 2016
http://jamanetwork.com/journals/jamasurgery/article-abstract/2577338
Sun Z, Sessler DI, Dalton JE, et
al. Postoperative Hypoxemia Is Common and Persistent: A Prospective Blinded
Observational Study. Anesthesia & Analgesia 2015; 121(3):709-715, September
2015
Stoelting RK. Continuous Postoperative
Electronic Monitoring and the Will to Require It. Anesthesia & Analgesia
2015; 121(3):579-581, September 2015
Khanna AK, Sessler DI, Sun Z, et
al. Using the STOP-BANG questionnaire to predict hypoxaemia
in patients recovering from noncardiac surgery: a
prospective cohort analysis. Br. J. Anaesth 2016; 116 (5): 632-640
http://bja.oxfordjournals.org/content/116/5/632.full
Belcher AW, Khanna AK, Leung S, et al. Long-Acting
Patient-Controlled Opioids Are Not Associated With More Postoperative Hypoxemia
Than Short-Acting Patient-Controlled Opioids After Noncardiac
Surgery: A Cohort Analysis. Anesthesia & Analgesia 2016; 123(6): 1471-1479,
December 2016
Regan R, Assad S. Dead in bed: A deadly hospital secret.
Healthy patients dying within hours of surgery. News 5 (Cleveland) 2016;
November 18, 2016
http://www.newsnet5.com/longform/dead-in-bed-a-deadly-hospital-secret
AAMI Foundation Healthcare Technology Safety Institute. Safeguarding
Patients With Surveillance Monitoring. The
Dartmouth-Hitchcock Medical Center Experience. 2013
Taenzer AH, Blike
GT. Postoperative monitoringThe Dartmouth experience. ASPF Newsletter 2012; 27(1):
1, 34, 21 (Spring-Summer 2012)
http://www.apsf.org/newsletters/pdf/spring2012v11_051512.pdf
Haines KL, Agarwa S. Postoperative
Pulmonary ComplicationsA Multifactorial Outcome. JAMA Surg
2016; Published online November 9, 2016
http://jamanetwork.com/journals/jamasurgery/article-abstract/2577336
Hopf HW. Preventing Opioid-Induced
Postoperative Hypoxemia: No Simple Answer? Anesthesia & Analgesia 2016;
123(6): 1356-1358, December 2016
CADTH (Canadian Agency for Drugs and Technologies in
Health). Capnography for Monitoring End-Tidal CO2 in Hospital and Pre-hospital
Settings: A Health Technology Assessment. Ottawa: CADTH 2016 (CADTH health
technology assessment; no.142); March 2016
https://www.cadth.ca/sites/default/files/pdf/HT0007_End-Tidal_CO2_Review.pdf
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